Table of contents

[binding_recto] [interleaf] [interleaf] [interleaf]
[titlePage_recto]
A
SHORT SYSTEM
OF
COMPARATIVE ANATOMY,
TRANSLATED FROM THE GERMAN OF
J.F. BLUMENBACH,
PROFESSOR OF MEDICINE IN THE UNIVERSITY OF GOETTINGEN.
BY
WILLIAM LAWRENCE,
FELLOW OF THE ROYAL COLLEGE, OF SURGEONS IN LONDON, AND
DEMONSTRATOR OF ANATOMY AT ST. BARTHOLOMEW’S HOSPITAL:
WITH
NUMEROUS ADDITIONAL NOTES,
AND AN INTRODUCTORY VIEW OF THE CLASSIFICATION
OF ANIMALS,
BY THE TRANSLATOR.
LONDON:
PRINTED FOR LONGMAN, HURST, REES, AND ORME,
PATERNOSTER-ROW.
1807.
[titlePage_verso]
Strahan and Preston,
Printers-Street, London.

[titlePage_recto]

TO
Sir JOSEPH BANKS, K.B.P.R.S. &c. &c.
WHOSE LABOURS HAVE SO MATERIALLY CONTRIBUTED
TO THE
ADVANCEMENT OF NATURAL HISTORY;
AND WHOSE MUNIFICENT PATRONAGE HAS SO SIGNALLY
PROMOTED EVERY BRANCH OF SCIENCE;
THIS HUMBLE ATTEMPT
TO FACILITATE THE STUDY OF
COMPARATIVE ANATOMY,
IS MOST RESPECTFULLY INSCRIBED,
AS AN
INDIVIDUAL TRIBUTE OF THAT ESTEEM AND ADMIRATION
WHICH ARE SO UNIVERSALLY FELT AND EXPRESSED
BY THE LOVERS OF SCIENCE,
IN ALL PARTS OF THE WORLD:

BY HIS MOST OBEDIENT SERVANT,
WILLIAM LAWRENCE.

John-Street, Adelphi,
April,
1807.

[titlePage_verso]

PREFACE.

[Seite v]

The object of the present publication is
to exhibit a concise, but at the same time
general and systematic view, of the structure
of the body throughout all classes of the ani-
mal kingdom. This science, which is very
aptly denominated, Comparative Anatomy, af-
fords the most essential aid in elucidating the
structure of the human body, and in explain-
ing the doctrines of physiology.

The want of any organ in certain classes of
animals, or its existence under different modi-
fications of form, structure, &c. cannot fail to
suggest most interesting conclusions concern-
ing the office of the same part in the human
subject. Thus our physiological reasonings,
which must necessarily be partial and incom-
plete, when deduced from the structure of a
single animal or class, are extended and cor-
[Seite vi] rected by this general comparative survey,
and may, therefore, be relied on with the
greater confidence. We are indebted to such
investigations for the discovery of the cir-
culation and of the lymphatic system; for the
elucidation of the functions of digestion and
generation: indeed, there is no branch of
anatomy or physiology which has not received
most material benefit from the same source.
Hence Haller has very justly observed,
that ‘“physiology has been more illus-
trated by Comparative Anatomy, than by the
dissection of the human body.”’

The study of Comparative Anatomy is
moreover of the greatest importance in its
connexion with veterinary science, and with
that highly interesting pursuit, natural history.
It would be an affront to my readers to enlarge
upon its utility in the former point of view;
but I may be allowed to observe on the latter
subject, that anatomical structure forms the
only sure basis of a natural Classification of
the animal kingdom; and that any arrange-
ment not founded on this ground-work will
lead us into the most gross and palpable errors.

[Seite vii]

Lastly, this study opens to the mind a great
source of interest and satisfaction, in exhibiting
such numerous and undeniable proofs of
the exertion of contrivance and design in
the animal structure: in displaying those mo-
difications of particular parts and organs, by
which they are adapted to the peculiar cir-
cumstances of the animal, and become subser-
vient to its wants, its necessities, or its enjoy-
ments.

The importance of the subject from the
above mentioned circumstances is now so
fully recognized, that it begins with justice
to be considered as an essential part of a regu-
lar medical education. Public lectures have
been delivered on it for some years in Germany
and France; and lately the example has been
followed in this metropolis. Yet a short
elementary treatise on the subject still remains
a desideratum*; and I have undertaken the
[Seite viii] translation of the present work, in order to
supply this defect. The author is well-
known throughout Europe for his successful
labours in Physiology and Natural History;
and has a particular claim on the public gra-
titude, for the excellent elementary treatises,
which he has published, on different branches
of the profession. The present work will not,
I trust, detract from his well-earned reputa-
tion.

If any reader should think that the author
has treated the subject with too much bre-
vity; the defect is compensated by the nu-
merous references to sources of more de-
tailed information, in the works of the best
and most approved preceding writers; parti-
[Seite ix] cularly to such as have given good plates of
the parts, which they describe. These quo-
tations may afford assistance even to those,
who have made some progress in the study.

I have taken the liberty of adding notes to
such parts as appeared defective either from
omission, or too great conciseness; and I have
placed these at the end of each chapter.
Many of these are derived from Cuvier’s
work, which I acknowledge in this general
manner, to save the trouble of numerous
references.

A short view of the Classification of Animals
is prefixed, for the accommodation of such
readers as may not not understand enough of
natural history. Blumenbach has pub-
lished a most excellent ‘“Manual of Natural
History,
”’ in German; and there is a similar
work in French, by Cuvier, entitled ‘“Tab-
leau Elementaire de l’Histoire Naturelle;
”’
either of which will be found very useful to
beginners.

W. LAWRENCE.

[[x]]

TABLE of CONTENTS.

[[xi]]

page

CHAP. I.

CHAP. II.

CHAP. III.

CHAP. IV.

CHAP. V.

CHAP. VI.

CHAP. VII.

[Seite xii]

CHAP. VIII.

CHAP. IX.

CHAP. X.

CHAP. XI.

CHAP. XII.

CHAP. XIII.

CHAP. XIV.

CHAP. XV.

CHAP. XVI.

[Seite xiii]

CHAP. XVII.

CHAP. XVIII.

CHAP. XIX.

CHAP. XX.

CHAP. XXI.

CHAP. XXII.

CHAP. XXIII.

CHAP. XXIV.

CHAP. XXV.

[Seite xiv]

CHAP. XXVI.

CHAP. XXVII.

INTRODUCTION,
containing
A SHORT ACCOUNT OF THE CLASSIFICATION OF ANIMALS,
IN WHICH THE TECHNICAL TERMS ARE EXPLAINED:
BY THE TRANSLATOR.

[Seite xv]

It is necessary for me to make a few remarks on the
classification of this animal kingdom; as the terms em-
ployed in the work differ occasionally from those of the
Linnean system, which has been hitherto chiefly followed
in this country. And, independently of this circum-
stance, such of my readers as have not particularly at-
tended to the study of natural history, may derive assist-
ance and information from a short sketch and explanation
of the arrangement of animals according to their anato-
mical structure, with an enumeration of the chief genera
in each order.

That the Linnean system is exposed to numerous and
well-grounded objections, and that in many instances it
disregards anatomical structure, which should form the
basis of a natural classification, will be readily allowed by
the most sanguine admirers of it’s illustrious author.
Yet it must be remembered, that the general adoption of
this method renders it desirable to deviate from it in as
few instances as possible; since the introduction of new
orders and names must necessarily create difficulty and
confusion in the study of the science. The French zoolo-
gists, whose successful labours in the advancement of
[[xvi]] natural history must be acknowledged with every due tri-
bute of respect, have carried the rage of innovation too
far, in the universal rejection of the Linnean method,
and the unnecessary multiplication of new orders and
genera. The defects or errors of any system could not
cause so much perplexity and inconvenience as the want
of a generally received standard, and the unlimited li-
cence, in which every individual indulges, of fabricating
new classifications and arrangements. To judge by some
recent works, we should be led to suppose, that the
merit of a systematic arrangement of animals does not
consist in the simplicity or intelligibility of the system;
but is in proportion to the number of newly-created
terms.

The Zoologie Analytique of Dumeril, (Paris, 8vo. 1806)
appears to have been constructed on this principle; and
recals to our mind the just and forcible observations of
Blumenbach, as expressed in his admirable work on The
Varieties of the Human Species.
‘“Alienissimus quidem
fum a nostericorum multorum novandi pruritu, qui
rebus naturalibus, quae pridem nominibus fuis vel in
vulgus notissimis, insignes funt, nova imponendo, miri-
ficé sibi placent: qui quidem onomatopoietarum lusus
ingentem studio historiae naturalis calamitatem attu-
lit.”’ Edit. 3rd, p. 16.

Animals may be distributed into two grand divisions:
those which have a vertebral column, and red-blood;
and those which have no vertebra, and are white-
blooded.

In the former division there is always an interior skele-
ton; a spinal marrow contained in the vertebral canal;
never more than four members, of which one, or both
pairs are wanting in some instances. The brain is con-
tained in a cranium: there is a great sympathetic nerve;
five senses; two moveable eyes; and three semicircular
[Seite xvii] canals in the ear.1 The circulation is performed by one
muscular ventricle at least. There are lymphatic, as well
as blood-vessels. The jaws being placed horizontally, the
mouth is opened by their moving from above downwards,
or from before backwards. There is a continuous ali-
mentary canal: peritoneum; liver, spleen, and pancreas,
two kidneys, and renal capsules; and two testicles.

The vertebral animals are subdivided into the warm
and cold-blooded.

Warm-blooded vertebral animals have been ventricles,
and a double circulation; and breathe by means of lungs.
The cranium is completely filled by the brain. The eyes
are closed by eyelids. The tympanum of the ear is hol-
lowed out of the cranium, and the labyrinth is excavated
in the bone. Besides the semi-circular canals, there is a
cochlea. The nostrils communicate with the fauces, and
allow the passage of air into the lungs. The trunk is
constantly furnished with ribs.

In cold-blooded vertebral animals the brain never entirely
fills the cranium. The eyes seldom possess moveable
eyelids. When the tympanum exists, it is on a level with
the surface of the head. ’There is no cochlea. The
different parts of the ear are connected but loosely to the
cranium.

The division of warm-blooded animals contains two
classes; Mammalia and Birds.

The mammalia are viviparous, and suckle their young
(from which circumstance the name is derived). They
[Seite xviii] have an uterus with two cornua; and the male has a
penis.

There are two occipital condyles: a very compli-
cated brain; four ossicula auditus, and a spiral cochlea.
The skin covered with hair. A muscular diaphragm se-
parates the chest and abdomen. There is an epiglottis.
The lower jaw only moves. The fluid in the lacteals is
white, and passes through several conglobate glands.
There is an omentum.

Blumenbach establishes the following orders in this
class:

This order forms two in the arrangement of Cuvier.
1st, Tardigrada; which includes the sloths. There
are no incisors in either jaw. There is a complicated
stomach, but no rumination. 2ndly, Edentata, tooth-
less animals. Some of these have no teeth; others want
the incisores and cuspidati. The tongue is long, slender,
and projectile, for seizing the insects on which the ani-
[Seite xix] mals seed; body covered with hard substances. The
armadillo, manis, ant-eater, and ornithorhyncus, or duck-
billed animal belong to this order.

The five first genera of this order, form the plantigrada
of Cuvier; animals which rest the whole of the foot on
the ground. They are less carnivorous than the others;
have a longer intestinal canal, and no caecum.

The sixth genus forms the Pedimana of the same
zoologist: as they possess a separate thumb on the hind
extremities only. They have a pouch in the abdomen
containing the mammae, and holding the young in their
early slate. One species, the kanguroo, (didelphis gigan-
tea
), must however be excepted. That is placed among
the rodentia; and does not possess the separate thumb.

The order carnivora of Cuvier, will include from the
7th to the 11th genus: both inclusive. The seal belongs
to his amphibia.

The last genus of this order, together with the phoca
(seals) constitutes the Amphibia of Cuvier. These ani-
mals have short members adapted for swimming.

Cuvier distributes the class mammalia into three grand
divisions:

Birds are oviparous; have a single ovary and oviduct;
a single occipital condyle; a very large sternum; and
anterior extremities adapted for flying.

They have three eyelids; no external ear; a cochlea
conical, but not spiral; a single ossiculum auditus; body
covered with feathers. The lungs are attached to the
surface of the chest; and penetrated by the air, which
goes all over the body: there is a larynx at each end of
the trachea; no epiglottis. The jaws are covered with a
horny substance. The chyle is transparent; no mesen-
teric glands; nor omentum. No bladder of urine; the
ureters terminating in a bag through which the eggs and
faeces come, viz. the cloaca.

This class cannot be distributed into orders so clearly
distinguished by anatomical characters as the preceding
one. Blumenbach divides them into two leading divi-
sions.

(A) Terrestrial Birds.

(B) Aquatic Birds.

The two classes of cold-blooded vertebral animals are the
Amphibia and Fishes.

The former, differing considerably from each other,
have very few common characters; for in different in-
stances they walk, fly, swim, and crawl. There is no ex-
ternal ear, nor cochlea; the brain is always very small.
The lungs are in the same cavity with the other viscera;
no epiglottis, omentum, nor mesenteric glands. Two ova-
ries and oviducts. Cloaca, through which the faeces and
urine are expelled; and in which the organs of genera-
tion terminate. Neither hair, feathers, nor mammae.

Fishes. Breathe by means of branchiae or gills; and
have no trachea, nor larynx. Organs of motion consist-
ing of fins. Nose unconnected with the organs of respi-
ration. Ear entirely inclosed in the head; the tympanum,
&c. being absent. Both jaws moveable. The place of the
pancreas supplied by the pyloric caeca. An urinary blad-
der. Two ovaries. Heart consisting of a single auricle
and ventricle. They may be distributed into two leading
divisions; the cartilaginous; whose skeleton consists of
cartilage: the bony; where it is formed of a more firm
substance.

(A) Cartilaginous Fishes.

[Seite xxvii]

(B) Bony Fishes, divided according to the situation of
their fins.

The animals which have no vertebral column, do not
possess so many common characters as the vertebral classes.
Their hard parts, when they have any, are generally placed
on the surface of the body. The centre of the nervous
system, instead of being inclosed in a bony case, lies in
the same cavity with the viscera. The oesophagus is ge-
nerally surrounded by a nervous chord coming from the
brain. Their respiration is not carried on by lungs; and
they have no voice. Their jaws move in various direc-
tions. They have no urinary secretion.

The invertebral animals were distributed by Linneus
into two classes; insects and worms (vermes). The ana-
tomical structure of these animals was very imperfectly
known, when the Swedish naturalist first promulgated his
arrangement. But the labours of subsequent zoologists,
and particularly those of Cuvier, have succeeded in esta-
blishing such striking and important differences in their
formation, that a subdivision of the Linnean clas-
ses became indispensibly necessary. The insects of
Linneus are divided into crustacea and insecta: and the
vermes of the same author form three classes; viz. mol-
lusca, vermes,
and zoophyta.

The mollusca derive their name from the soft fleshy na-
ture of their body. This class includes those pulpy
animals, which may either be destitute of an external co-
vering; when they are called mollusca nuda; as the lug:
or may be enclosed in one or more shells, as the snail,
oyster, &c. when they are termed testacea.

[Seite xxix]

The animals of this class have no articulated members:
they have blood-vessels, and a true circulation. They
respire by means of gills. They have a distinct brain,
giving origin to nerves; and a spinal marrow.

Cuvier classes the numerous genera of this order un-
der the three following divisions; 1st, cephalopoda, (from
κεφαλη the head, and π [...]ς the foot) which have their or-
gans of motion placed round the head: 2dly, gasteropoda,
(from γαςηρ the belly, and π [...]ς), such as crawl on the
belly: and 3dly, acephala, (from α privative, and κεφαλη
which have no head. The three first genera belong to the
first division; the ten succeeding ones come under the
second; and the remainder exemplify the last order.

[Seite xxx]

According as the shell of the testaceous mollusca consists
of a single convoluted tube; or of two or more separate
pieces, they are called cochleae bivalves, multivalves, &c.

Crustacea possess a hard external covering, and nu-
merous articulated members. A long nervous chord,
beset with ganglia. Compound eyes. Antennae and
palpi like those of insects. A heart and circulating vessels;
and gills. Teeth in the cavity of the stomach.

Insects have articulated members and antennae. Those
which fly are subject to what is called a metamorphosis:
they pass through certain intermediate states of existence,
before they assume the last, or perfect form. From the
egg proceeds the larva, or caterpillar: this changes to the
chrysalis, nympha, or aurelia; from which the perfect in-
fect is produced. Nervous system consisting of a chord
beset with ganglia. No heart nor blood-vessels. Respi-
ration carried on by means of tracheae.

The Vermes may be divided into two orders; the
intestinal, which inhabit the bodies of other animals; and
the external.

The former are not of such a complicated organisation
as the latter; so that they are sometimes arranged among
the zoophytes. The external worms have a nervous chord
possessing ganglia, an elongated body composed of rings;
and having no distinct head. There are no members.
Circulating vessels, but no heart. No nerves have been
discovered in the intestinal worms.

[Seite xxxiii]

The Zoophytes have neither brain nor nerves; no
heart, nor, perhaps, blood-vessels; no articulated mem-
bers.

Lately published, by the same Author,

[[xxxiv]]

A Description of the Arteries, arranged in the Form of
Tables, for the Use of Students; translated from the
Latin of A. Murray, Professor of Anatomy at Upsal.

COMPARATIVE OSTEOLOGY.

[[xxxv]] [interleaf]

CHAPTER I.
ON THE BONES OF ANIMALS IN GENERAL.

[Seite 1]

§ 1. Red-blooded1 animals only possess a
true skeleton; to which all their bones2 are con-
nected, and on which the general form3, as well
[Seite 2] as the greater or less flexibility of the body de-
pend.

§ 2. The ordinary white4 colour of the bones
has several gradations, which are sometimes ob-
servable in the different parts of the same bone;
as in the grinding teeth of the elephant*, And,
in some few genera the whole bony structure is
of a different colour5. Thus, in the garpike, (esox
belone
) the bones are green; and in some varie-
[Seite 3] ties of the common fowl they approach to a black
colour6.

§ 3. The structure of the bones is subject to
still greater variations; which occur in the diffe-
rent bones of the same skeleton, as well as in the
whole skeleton of particular classes and orders. In-
stances may be observed in the dry and brittle tex-
ture of the air bones of birds; in the long fibres,
which appear on splitting the bones of the larger
amphibia and fishes; in the peculiar tenacity and
solidity of individual parts in some, cartilaginous
fishes*.

§ 4. Excepting the crown of the teeth, bones
are universally covered with periosteum; and for
the most part they contain marrow7 internally;
[Seite 4] which varies much in consistence, being fluid in the
whales.

§ 5. Bones are formed by the ossification of ori-
ginal cartilages; the teeth being again for the most
part excepted. Ossification commences earlier and
proceeds more rapidly in viviparous, than in ovi-
parous animals8. This fact appears at least from
comparing the incubated bird with the foetus of
mammalia. Again, in the latter class, many points
in the formation of the bones are completed sooner
in quadrupeds than in man*9.

Additional Notes on the First Chapter.

[Seite 5]

(A) Ossification does not go on with equal rapi-
dity in all animals, nor in all the bones of the same
animal. Thus the ossification of the internal ear
of man, and the mammalia, is completed before
any other parts; and it surpasses all other bone in
its density, and in the proportional quantity of
phosphate of lime, which it contains. In the cetacea,
particularly the balaena and physeter (the black and
white whales,) this part acquires a density and hard-
ness equal to that of marble. Its section presents an
homogeneous appearance, without the least vestige
of fibres, cellular texture, or vessels.

Bones are slow in acquiring their complete
formation, in proportion to the remoteness of the
period, at which the growth of the animal is
finished. The skeleton remains constantly in a
cartilaginous state in some animals; such are the
shark, skate, sturgeon, and all those fishes, which,
[Seite 6] from this circumstance, have been denominated
cartilaginous, or chondropterygii. Although the
bones of other fishes, of reptiles, and serpents ac-
quire a greater hardness, they constantly remain
more flexible, and retain a larger proportion of
gelatine in their structure, than those of warm-
blooded animals.

The bony texture of the mammalia is not so fine
and delicate as that of man: it is particularly loose
and coarse in the cetacea, where the distinction of
the fibres is very manifest, even on the external
surface. In the jaw and the ribs particularly, they
may be loosened by maceration, and become very
obvious.

The bones of reptiles and fishes have a very
homogeneous appearance, the earthy matter and
the gelatine appearing to be uniformly mingled:
this is more strikingly marked, as we approach to
the cartilaginous fishes, where the gelatine predomi-
nates, and conceals the earth.

Several animals have no medullary cavities even
in their long bones. This is the case with the
cetacea, the seal, and turtle.

The structure of the bones of birds should be
noticed in this place. They are almost universally
hollow: but their cavities, which never contain
marrow, are filled with air. This organization
unites the advantages of lightness and strength.
For a further account of it see the chapter on the
organs of respiration.

[Seite 7]

The horn of the stag is a real bone, as appears
both from its texture, and its component elements.
Its outer part is hard, compact, and fibrous: the in-
ternal substance is reticulated, but very firm; and
possesses no cavities nor marrow. See the chapter
on the skeleton of the mammalia, for the mode of
its formation, &c.

The shells of the testaceous animals are formed
of a calcareous substance, which is sometimes
laminated; sometimes as hard and denfe as mar-
ble. This is mingled, as in other bones, with a
gelatinous matter, from which it may be separated
by means of acids. The earth is not disposed in
fibres or laminae, as in other bones; but is uni-
formly expanded through the animal substance.

The layers of the shell are formed successively,
as the animal increases in size. The exterior or
smallest are formed first: others are successively
deposited on the inner surface of these; each new
layer extending beyond the margin of the former
one, so that the shell, by every addition increases
in thickness and circumference. Are these new
layers formed by vessels existing in the shell itself,
or are they produced by exudation from the sur-
face of the animal? Reaumeur broke the shell
of snails, and found that no reproduction took
place, when he covered the exposed part of the
animal’s body; while the injury was quickly re-
paired, when no artificial obstacle impeded the
effusion of fluids from the surface. This experi-
[Seite 8] ment seems to prove that the shell is formed by
deposition from the body of the animal: but there
is an argument equaily strong in favour of the ex-
istence of vessels in the shell itself. Between the
two last formed layers of the convex shell of the
oyster, a considerable cavity is found, filled with a
fluid, and communicating by a particular opening
with the internal parts of the body. This must be
destroyed and reproduced whenever a new lamina
is added; and we cannot understand how such
processes can be effected without arterial and ab-
sorbing vessels.

Grustaceous animals, (crab, lobster, &c.) have a
skeleton which surrounds and contains their soft
parts, and which serves at the same time the pur-
poses of a skin. When it has attained its perfect
consistence, it grows no more: but as the soft
parts still increase, the shell separates, and is de-
tached, being succeeded by a larger one. This
new covering is partly formed before the other
separates: it is at first soft, sensible, and vascular;
but it speedily acquires a hard consistence by the
increased deposition of calcareous matter.

Some of the mollusca have hard parts in the in-
terior of their body. The common cuttlefish (sepia
officinalis
) has a white, firm, and calcareous mass
of an oval form, and slightly convex on its two
surfaces, commonly known by the name of the
cuttlefish-bone, contained in the substance of its
body. It has no connection with any soft part,
[Seite 9] whence it appears completely as a foreign body:
no vessel nor nerve can be perceived to enter it;
nor does it receive the attachment of any tendon.
In the calmar (sepia loligo), this body resembles
horn in its appearance; it is transparent, hard, and
brittle. Its form resembles that of a leaf, except
that it is larger; and sometimes that of a sword-
blade. These parts must grow like shells, by the
simple addition of successive layers.

(B) As chemical analysis has discovered some
interesting differences in the constituent ingredients
of the hard parts of various animals; it seems
right to give a short account of them in the pre-
sent place.

The bones and teeth of red-blooded animals,
consist chiefly of phosphate of lime, deposited in
the interstices of an animal substance; which, when
freed from the earthy matter by the immersion of
the bone in an acid, approaches in its consistence
to cartilage. This is completely dissolved by boil-
ing in a close vessel, and is thereby proved to con-
sist of gelatine. A small quantity of carbonate of
lime is mixed with the phosphate; and hence ef-
fervescence arises when a bone or tooth is sub-
jected to the action of acids.

The relative proportions of these ingredients in
the general structure of bone have not hitherto
been determined with much accuracy; but the
obvious differences of structure and appearance
[Seite 10] not only in the different classes, orders, and genera,
but even in the several bones of the same individual,
and in parts of the same bone, leave no doubt that
much variation must exist in these points.

The horn of the stag is bone, containing a large
proportion of gelatine.

The bones of fishes contain phosphate of lime;
but the animal substance exists in very large pro-
portion, particularly in those which are called car-
tilaginous, where it completely obscures the earthy
matter.

Carbonate and phosphate of lime, deposited on a
cartilaginous basis, which retains the form of the
part, after the earthy matter has been separated,
constitute the external covering of the crustaceous
animals (crab, lobster, &c.). The carbonate is in
greatest quantity.

Carbonate of lime, with a small quantity of phos-
phate, forms the earthy principle of the shell of
the echinus.

The shells of the testacea, are entirely composed
of carbonate of lime, united to a gelatinous sub-
stance. When immersed in acid, a rapid effer-
vescence ensues. Some of them, which are very
hard in their texture, and have an enamelled sur-
face, contain so little animal matter, that it does not
retain the form of the shell, which is completely
dissolved by acids, like the enamel of the teeth.
But others, which consist of what is called mother
of pearl, and are formed by successive strata, (e.g.
[Seite 11] the oyster, muscle, &c.) contain a much larger pro-
portion. When these have been macerated in acid,
a gelatinous substance remains, consisting of se-
veral layers of membrane, arranged stratum super
stratum.

It appears therefore, that phosphate of lime is the
peculiar earth of bone, and carbonate that of shell;
although no bone has been hitherto discovered,
without a small admixture of the latter ingredient.
Hence that singular production from the body of
the cuttle-fish is improperly called bone; as it con-
sists, like shells, of various membranes, hardened
by carbonate of lime, without any phosphate. See
‘“Experiments and Observations on Shell and Bone,”’
by C. Hatchett, Esq. Philos. Trans. 1799.

The same excellent chymist has also found, that
the zoophytes, consist of carbonate of lime joined in
different instances to various proportions of animal
substance. Philos. Trans. 1800, part 2.

CHAPTER II.
ON THE SKELETON OF MAMMALIA.

[Seite 12]

§ 6. The form of the different mammalia, par-
ticularly the fourfooted ones, varies consider-
ably; and their skeletons must be marked by cor-
responding differences. Yet these varieties may
be included, at least for the greatest part, under
the following peculiarities; which serve to distin-
guish their skeletons from those of birds.

The skeletons of mam-
malia possess;
Those of birds are dis-
tinguished by;
1. A skull with ge-
nuine sutures, (at least
with very few exceptions;
as perhaps the elephant,
and the duck-billed ani-
mal1, ornithorhyncus).
1.* A skull which
has not real sutures2.
2. Jaws furnished with
teeth.
2. A bill without
teeth.
Except the ant-eaters,
the manis, the duck-billed
animal*, the balaena
(whale).
3. An upper jaw,
which does not move.
3. An upper jaw,
which does move.
There are some ex-
ceptions, viz. the rhino-
ceros bird.
4. An os intermaxil-
lare.
4. No os intermaxil-
lare.
(For the probable ex-
ceptions, see § 14.)
5. Two occipital con-
dyles.
5. A single occipital
condyle.
6. Seven cervical ver-
tebrae.
6. More than seven
cervical vertebrae.
Except the three-toed
sloth
, and some cetacea.
7. Moveable dorsal
vertebrae.
7. Motionless dorsal
vertebrae.
8. A pelvis closed in
front.
8. A pelvis open an-
teriorly.
Except the ant-eaters;
which have it open: and
the cetacea, which have
none.
Except the ostrich.
9. True clavicles in a
few genera only.
9. Clavicles constant-
ly: and almost as uni-
versally the fork-like bone.

§ 7. We shall first describe the cranium of
mammalia; since its structure mod materially in-
fluences the whole animal economy, from serving
as a receptacle for the brain, the organs of sense,
and those of mastication.

§ 8. The well known division of the bones of
the head, into those of the cranium, and of the
face, is convenient for pointing out the remarkable
proportions of relative magnitude in the two divi-
sions3. Compare, for instance, the skull of the
orang-outang (simia satyrus) with that of the man-
dril (papio maimon
); or that of the porpoise, with
the white whale.

§ 9. The number of proper bones of the cranium
is, on the whole, the same as in the human subject.
The os frontis in most of the horned animals, is com-
posed of two equal portions: the two parietal bones
are consolidated into one in many of these, and in
others they are united to the occiput. Some of
[Seite 15] the glires have a separate piece between the parietal
and occipital bones4*.

§ 10. A principal variation in the form of the
cranium, arises from the size and direction of the
crista occipitalis, which bears a determinate pro-
portion to the strength of the jaws. It is wanting
in the orang-outang; but is very large in the baboon
of Borneo.
5. The longitudinal crista is very strongly
expressed in the badger; and the transverse ridge
is remarkable in the beaver. Between the arched
sides of the upper part of the cranium in the ele-
phant,
lies a broad and deep impression, with a lon-
gitudinal crista at its bottom.

There is considerable difference in this respect,
between the different races of dogs: viz. between
the pug-dog, and that of Newfoundland.

§ 11. The situation and direction of the great
occipital foramen
are attended with remarkable va-
[Seite 16] riations in some instances. Instead of lying hori-
zontally, as in the human subject, (where indeed
the anterior margin is sometimes higher than the
posterior) it is placed in most quadrupeds at the ex-
tremity of the cranium, and obliquely, with the
posterior border turned upwards. In some, indeed,
its direction is completely vertical; and in the mar-
mot of the Alps,
its upper margin is turned more
forwards than the lower6*.

§ 12. The sutures, which connect the indivi-
dual bones of the cranium, are generally less intri-
cate, at least to outward appearance, in quadrupeds
[Seite 17] than in man. Their teeth are however strong and
sharp in the horned pecora, for obvious reasons;
and the frontal bones are thick in the same ani-
mals7. Ossa triquetra are seldom seen in the cra-
nia of animals. Yet I have specimens of these, in
the hare and orang-outang; the sutures of the latter
are remarkably elegant8.

§ 13. The general form9 of the cranium, is
most materially influenced by the direction, and
[Seite 18] the various degrees of prominence of the facial
bones. The projection is generally formed by a
prolongation of the upper jaw; partly also, and in
many instances chiefly by the intermaxillary bone,
which is inclosed between the two upper jaw
bones*.

§ 14. The upper jaw-bones of other mammalia,
do not, as in man, touch each other under the
nose, and contain all the upper teeth; but they
are separated by a peculiar, single, or double in-
termaxillary bone
10, which is in a manner locked
between the former, and holds the incisor teeth11
of such animals, as are provided with these teeth.
It exists also in the pecora, which have no incisor
teeth in the upper jaw; as well as in such genera
[Seite 19] as have no incisor teeth at all; viz. the duck-
billed animal,
and the armadillo. It is even found
in those mammalia, which are wholly destitute of
teeth; as the anteater, and the proper whales12.
It is joined to the neighbouring bones by sutures,
which run exteriorly by the side of the nose and
snout, and which pass, towards the palate, close to
the foramina incisiva13. Its form and magnitude
vary surprisingly in several orders and genera of
mammalia. It is small in many ferae; as also in
[Seite 20] the walruss (Trichecus). In the glires* it is gene-
rally remarkably large; viz. in the beaver and mar-
mot.
It is also large in the hippopotamus, porpoise,
and cachalot (physeter macrocephalus). Its form is
very remarkable in the ornithorhynchus, where it
consists of two hooklike pieces, joined by a broad
synchondrosis14.

§ 15. The above-mentioned anterior palatine
holes,
or foramina incisiva are double in most mam-
malia, as in man. They are much larger in
quadrupeds than in the human subject: in the
[Seite 21] pecora and the hare they are remarkably long and
broad15.

§ 16. There are remarkable impressions in the
upper jaw of most pecora, near the nasal bones,
arising from the situation of the sinus sebacei. This
part has a reticular structure in the hare, which
approximates in that, as well as in many other
points, to the formation of the ruminant animals.

§ 17. In the zygoma we observe several important
differences, immediately derived from the organs of
mastication16. It is commonly formed by the junc-
tion of the cheek-bone with the os temporis. In seve-
ral web-footed and digitated mammalia, (viz. the
otter, beaver, opossum, guinea-pig,) there is a peculiar
bone interposed between these. It is straight, and
almost of a thread-like slenderness in the mole. It
is of immense strength, and includes a large space
towards the cranium, for lodging the powerful mus-
cles which move the lower jaw, in several carnivo-
rous animals,
as the tiger, and in some glires, as the
beaver. In the rat, and some others, it is convex
[Seite 22] below; in the weasel, above. It is remarkable in
the sloth for a large descending process, which comes
from the os malae*.

§ 18. The elephant possesses only a kind of imi-
tation of nasal bones. In most apes, and even in
the orang outang, there is a single, triangular, and
and very small nasal bone. In the greater number
of true quadrupeds, there are two ossa nasi, fre-
quently of very considerable magnitude. This is
the case in the pecora and hare; also in the horse,
pig,
&c. In the rhinoceros, the ossa nasi, which
support the horn, are very soon consolidated to-
gether.

§ 19. The lacrymal bones (ossa unguis) are en-
tirely wanting in the elephant. They are particu-
larly large in the pecora; and above all in the
antelope. They are also very remarkable in the
opossum.

§ 20. The orbits differ very much in their direc-
tion, capacity, and depth. They have for the most
part a lateral direction. In the simiae they are di-
rected forwards, as in man: but they lie much
more closely together than in the human subject.
In the beaver they point upwards.

They are completely closed in the quadrumanous
[Seite 23] mammalia. In the pecora and solidungula they
have a circular margin in front; but the outer
part is deficient behind. In the ferae and several
glires the outer part of their margin is also deficient.
The depth of these cavities is equally various. In
many cases they are so superficial as scarcely to de-
serve the name of orbit; viz. the mole, and anteater.
Haller’s assertion, that man possesses a larger
bony orbit than any animal, is erroneous. The
orbit of the cat is comparatively larger, as also that
of several makis, (lemur). See the delineation of
their crania in Fischer’s valuable ‘“Anatomy of
the Maki.
”’ Frankfort 1804, 4to*.

§ 21. In mammalia, which have horns, these
parts grow on particular processes of certain bones
of the cranium. In the one horned rhinoceros, they
adhere to a rough, and slightly elevated surface of
the vast nasal bone. The front horn of the two
horned species has a similar attachment; the poste-
rior rests on the os frontis17; as those of the horned
pecora do. Two kinds of structure are observed
in the latter: there are either proper horns, as
in the genera of the ox, goat, and antelope, or bony
productions, as in the genus cervus, which includes
animals of the deer kind. These are also called
[Seite 24] horns in English, or sometimes antlers: in French
bois de cerf. In the former, the external table of the
frontal bones is elongated into a process, which
contains a continuation of the frontal sinuses, ex-
cept in the antelope. Its external vascular surface
secretes the horn, which covers this process like a
sheath. In the stag kind18 (in the male19 only
in most genera), the frontal bone forms a short
flattened prominence, from which the proper antler
immediately shoots forth. It is renewed every
year, and is covered, during the time of its growth,
with a hairy and very vascular skin*20. The little
[Seite 25] horns of the giraffe hold a middle place between
these two divisions. In their form, structure, and
permanent duration, they resemble the frontal pro-
cesses of the proper horns: in their hairy covering
they approach to the branches of the stag kind21.

§ 22. The skeleton of quadrupeds deviates more
from that of man in the form of the lower jaw bone,
than in any other part. This difference consists
chiefly in the want of a prominent chin; that pecu-
[Seite 26] liar characteristic of the human countenance; which
exists in every race of mankind, and is found in no
other instance whatever. Man has also the shortest
lower jaw in comparison with the cranium; the
elephant perhaps approaching the nearest to him
in this character22. The same bone is further dis-
tinguished by the peculiar form and direction of
its condyle. The articulation of these processes
varies according to the structure of the masticating
organs. They are both situated in the same straight
horizontal line in the ferae; their form is cylindri-
cal; and they are completely locked in an elongated
glenoid cavity, whose margins are so extended be-
fore and behind the condyle, that all rotatory mo-
tions are rendered impossible, and hingelike move-
ments only allowed. This structure is most striking-
ly exemplified in the badger, where the cylindrical
condyles are so closely embraced by the margins of
the articular cavity, that the lower jaw, (at least in
the adult animal,) is still retained in its situation,
after the soft parts have been entirely removed by
maceration. In many herbivorous animals (in the
most extensive sense of the term) these condyles
are really rounded eminences; viz. in the elephant
and beaver. Their surface is flattened in the pecora,
which have also the lower jaw narrower than the
upper, so that the two sets of teeth do not meet
together, when the mouth is shut; but are brought
[Seite 27] into contact by the free lateral motion, which takes
place in rumination. The two condyles lie parallel
to each other in a longitudinal direction in many
glires; viz. in the hare, where, (as in the anteater)
the coronoid process is almost entirely wanting.
This process is on the contrary very conspicuous in
the giraffe. The cetacea have the articular surface
of the lower jaw turned almost directly back-
wards23*.

There are on the whole, few other bones in the
skeleton of mammalia, of such various forms as the
lower jaw. The most anormalous formation of this
bone is the shovel-like surface of its anterior part
in the duck-billed animal.

We have lastly to observe that the two halves of
the lower jaw are connected throughout life, in
many mammalia, by a mere synchondrosis; which
is easily separated by boiling or maceration. This
is the case in many ferae, glires, and cetacea. They
are consolidated into one piece, as in the human
subject, at an early period, in the quadrumana, as
also in the horse, horned cattle, pig, elephant, &c.

§ 23. The jaws of mammalia contain teeth24
[Seite 28] with a very few exceptions: the proper whales,
(balaenae), the manis, (scaly lizard), and the
American anteaters are the only genera entirely
destitute of these organs*.

The substance and texture of the teeth are different
from those of all other bones. The enamel which
covers the crown of the tooth, is characterised by
its peculiar hardness, (sparks of fire may be pro-
duced by striking it against steel), as well as by the
want of animal matter, with which the bony part
of the crown, as well as the fang of the tooth are
copiously provided. It seems to be wanting in the
tusks of the elephant, as also in those of the wal-
russ,
and of the narwhal, (monodon, sea-unicorn).
Yet these are all surrounded by an external thin
coat of a different substance from the body of the
tooth. These teeth have indeed some peculiarity
in their texture; the ivory of the elephant’s tusks
in particular is unlike any other substance25.
[Seite 29] In some animals the crowns of particular teeth are
distinguished by peculiar colours. The incisors
of some glires, as the beaver, marmot, and squirrel,
are of a nut-brown colour on their anterior surface,
and the molar teeth of several bisulca, (cloven-
hoofed animals), as well as of the elephant, are
covered by a very hard black substance of a vitre-
ous appearance26.

[Seite 30]

§ 24. It is difficult to frame a classification of
the teeth, which shall be generally applicable, and
at the same time intelligible. Their situation af-
fords perhaps a more eligible basis of arrangement
than their form, since that is the same throughout,
in some instances, as the cachalot and porpoise. They
may therefore be distributed into the three classes
of front teeth, corner teeth, and back teeth*.

§ 25. The front teeth in the upper jaw, are
those which are implanted in the intermaxillary
bone, (the tusks of the elephant must therefore be
included); in the lower jaw, such as correspond to
these, or to the anterior margin of the intermaxillary
bone, in animals which have no upper incisors.
Their number and form vary considerably. In the
glires their cutting edge is formed like a chissel,
particularly in the lower jaw, whence J. Hunter
called these animals ‘“scalpris dentata.”’ In some
cases, as the beaver, and the domestic mouse, the
lower ones have remarkably long roots. In the
hare there are two very small teeth placed just be-
hind the large ones. The crowns of the front, as
well as of the back teeth, form flat prominences in
the walrus. The front extremity of the lower jaw,
[Seite 31] with its teeth, extends in the dolphin (delphinus
delphis
) much beyond the corresponding part of
the upper jaw, contrary to what happens in other
animals. The lower fore teeth of most mammalia
have a more or less oblique position; while in man
they are perpendicular. The orang-outang of Bor-
neo, is the only animal, which at all approaches to
the human structure in this point.

§ 26. The corner teeth (canini) of the upper
jaw, lie close to the intermaxillary bone; hence the
remarkable spiral tusk of the narwhal26, and the
tusks of the walrus belong to this division. In
many baboons, and most particularly in the larger
predacious mammalia, these teeth are of a terrific
size; in the latter animals, the whole profile of the
anterior part of the cranium, forms a continuous
line with these teeth; which is very visible in the
tiger. The canine tusk of the babiroussa, which are
very long, and recurved so as nearly to describe a
complete circle, present the most curious structure.
Their utility to the animal, appears quite obscure,
when their length, direction, and smallness are con-
sidered. The small canine teeth, which are situated
[Seite 32] just behind the larger ones, in all the species of the
bear27 kind, are also remarkable.

§ 27. The back teeth are the most universal;
since, when mammalia have any teeth at all, they
are of this description, although the front and canine
teeth may be wanting; as in the armadillo, and the
ornithorhynchus. The narwhal makes the only
exception, as it is perfectly toothless, if we except
the long tusk. The form, structure, and relative
situation of the back teeth vary very considerably.
In many quadrumana, as in man, the two front ones28
are smaller in the crown, and more simple in the
fang than the posterior. Whence J. Hunter calls
[Seite 33] them bicuspides, and restricts the name of molares to
the latter29.

The molar teeth of ferae have the crown en-
tirely covered with enamel30; while in several31
glires, in the solidungula, pecora32, and most balenae,
bony substance may be seen at the extremity of the
tooth, intermixed in a tortuous line with vertical
productions of enamel33*. In many animals, which
[Seite 34] feed on grass, and do not ruminate, as the solidun-
gula
and the elephant, the broad crowns of the
grinding teeth lie chiefly in an horizontal direc-
tion towards each other. In most pecora, on the
contrary, their surface, which forms a zig-zag line,
is oblique; the outer margin of the upper teeth,
and the inner margin of the lower teeth, being the
most prominent. In most predacious animals, par-
ticularly of the lion and dog kind, the crowns of
the molar teeth are compressed, and terminate in
pointed processes, the lower ones shutting within
the upper; so that in biting they intersect each
other, like the blades of a pair of scissars, in conse-
quence of the firm hinge-like articulation of the cy-
lindrical condyle.

§ 28. Certain classes of the teeth are entirely
wanting in some orders, classes, and genera of qua-
drupeds; as the upper front teeth in the pecora, the
lower in the elephant, both in the African rhinoceros,
and the canine in the glires. In other instances,
the different descriptions of teeth, particularly the
canine and molar, are separated by considerable in-
tervals; this happens in the horse and bear. There
is no animal, in which these parts are of such equal
height, and such uniform arrangement as in
man*.

[Seite 35]

§ 29. The want of satisfactory observations34,
prevents us from saying much on the change of the
teeth, particularly in wild animals. Some erroneous
opinions of former times, as, for instance, that the
domesticated pig changes its teeth, and that the
wild animal does not, hardly require an express
contradiction in the present day. During the time
of change in the serae, particularly in the dog and
otter, the number of their canine teeth often seems
doubled; since the permanent ones cut the gum,
before the deciduous have fallen out. Apes, like the
human subject, have no bicuspides among the de-
ciduous teeth: but there are, instead of these, two
proper molares on either side of the jaw35. The
change of the teeth takes place in the elephant, in a
very remarkable manner. The new permanent
tooth comes out behind the milk tooth36; the ver-
tical layers of which are gradually removed37, as
the formation of the latter advances*38. There is,
[Seite 36] however, perhaps no animal of this class, in which
the first appearance, and subsequent removal of the
deciduous teeth take place, at so late a period of life
as in man.

§ 30. The crown39 of the tooth is gradually
worn down by the act of mastication, and receives
from this cause, a kind of polished surface, which is
especially observable in the canine teeth of the pig
and hippopotamus. The age of the horse is deter-
mined by the appearance of the front teeth.

§ 31. From the head of mammalia, we proceed
to consider the trunk, according to its division into
the three principal parts of spine, pelvis, and chest.
The former of these is the most constant part of the
skeleton; as it belongs to all red-blooded animals
without exception, and is not found in a single
white-blooded one.

[Seite 37]

§ 32. It is remarkable, that the animals of this
class constantly agree in the number of their cervi-
cal vertebrae. The giraffe, or the horse, have neither
more nor fewer than the mole or ant-eater. They
are always seven, as in the human subject. An un-
expected irregularity has been discovered by Cu-
vier
in the three-toed sloth; it has nine vertebrae
of the neck. In some cetacea, on the contrary,
there are only six*; and, in these animals, four or
five are generally consolidated together. The atlas
is distinguished in the ferae by its immense strength,
and by the vast size of its tranverse processes40:
the vert. dentata is equally conspicuous for its
spinous process.

§ 33. The number of dorsal vertebrae is de-
termined by that of the ribs, which will be spoken
of presently. In the long-necked quadrupeds, as
the horse, giraffe, camel, and other pecora, as well as
in those animals whose head is very heavy, as the
elephant, the spinous processes of the anterior dorsal
vertebrae are exceedingly long, for the attachment
of the great suspensory ligament of the neck (liga-
mentum nuchae
).

[Seite 38]

§ 34. The lumbar vertebrae vary much in
number. The elephant has only three; the camel
seven. Some quadrumana, as the mandrill, have
the latter number. The horse has six; the ass five.
(Mules have generally six, but sometimes only five.)
Most quadrupeds have the processes of these verte-
brae turned forwards (which is upwards41 in the
ape, in its ordinary position). The tranverse pro-
cesses are remarkably large in many ruminantia, as
also in the bare.

§ 35. The form and proportions of the sacrum
are still more various. The number of its verte-
bra, as they are called, varies in the different spe-
cies of the same genus. Thus, in most42 of the
simiae, it consists of three pieces; in the43 orang-
outang
of four44; in the chimpanse* of five. This
bone is distinguished in the horse by large lateral
processes at its anterior extremity; and in the mole
[Seite 39] by a thin sharp edged plate, formed by the union
of its spinous processes*. As the cetacea have no
pelvis, they cannot be said to possess a sacrum.

§ 36. The os coccygis is prolonged, so as to
form the tail of quadrupeds; and consists therefore,
in many cases, of a great number of vertebrae. In
the cercopithecus morta there are 22; in the cerc.
paniscus
32; in the two-toed ant-eater 4145. (See
note (Y), at the end of the chapter.)

§ 37. The ossa innominata, together with the
sacrum, constitute the pelvis46. There is ground
for affirming, although the assertion may appear pa-
radoxical, that no animal but man has a pelvis;
for in no instance have the bones of this part that
bason-like appearance, when united, which belongs
[Seite 40] to the human subject. Those apes, which most
nearly resemble man, have the ossa innominata much
elongated; and in the elephant, horse, &c. the
length of the symphysis pubis detracts from the
resemblance to a bason. In some instances, as in
the beaver and kangaroo, the ossa pubis are not
united by synchondrosis, but consolidated into one
piece by a bony union47. They are, on the con-
trary, separate in the ant-eaters, in the same manner
as they are found in birds. The cavity of the pelvis
is so narrow in the mole, that it cannot hold the
organs of generation and neighbouring viscera,
which lie therefore externally to the ossa pubis.
In the kangaroo48, and other marsupial* animals, the
superior, or rather the anterior margin of the ossa
pubis, is furnished with a peculiar pair of small
bones, (ossa marsupialia, or cornua pelvis abdominalia)
somewhat diverging from each other, and running
towards the abdomen. They have an elongated
and flattened form, and belong exclusively to these
animals. But in the Philos. Trans. of 1802, it is
[Seite 41] stated by Mr. Home, that the ornithorhynchus has
something of this kind. They support the abdo-
minal pouch in the female, but are also found in
the male; at least in some species49. Cetaceous
animals have no hind feet, nor ossa innominata,
consequently no pelvis: they have, however, a pair
of small bones at the lower part of the belly, which
may be compared to the ossa pubis50.

§ 38. The thorax in most, if not all animals of
the class mammalia, is narrower, and on the con-
trary, deeper from the spine to the sternum, than in
man. The less marked flexure of the ribs of ani-
mals, and the elongation of their sternum give rise
to this peculiarity. The long legged animals, as the
giraffe, and those of the stag kind, possess this keel-
[Seite 42] like form of the chest (thorax carinatus) in the most
striking degree.

§ 39. In a very few mammalia, as some bats and
armadillos, there is a pair of ribs less than in man;
but in the greater number of this class there are
more. Several quadrumana have 14 pairs; the
horse 18; the elephant 1951; the two-toed sloth
(bradypus didactylus) 23. The two-toed ant-eater
(myrmecophaga didactyla) has 16 pairs, which are
remarkably broad, so that the back and sides of the
skeleton, as low as the ossa innominata, appear like
a coat of mail. (See note (A a) at the end of the
chapter).

§ 40. The sternum in most of the mammalia
is cylindrical, and jointed. This structure occurs
even in the quadrumana and the bears, whose skele-
tons, in other respects, resemble the human. The
form of this bone is the most singular in the mole;
where its anterior52 extremity is prolonged into a
[Seite 43] process, almost resembling a ploughshare, lying un-
der the cervical vertebrae, and parallel with them.
(See the note (B b) at the end of the chapter.)

§ 41. We proceed to speak of the extremities,
as they are called, which, although they vary con-
siderably in the class of mammalia, may, on the
whole, be compared to those of man in their chief
component parts, and in the mode53 in which these
are connected together. (See note (C c) at the
end of the chapter).

S 41. The clavicle has been said, even by some
[Seite 44] excellent modern zoologists, to be confined to
Linnaeus’s order primates (in which he includes
man, the quadrumanous animals, and bats) but it
exists in a great number of mammalia54 besides
these: particularly in such quadrupeds, as make
much use of their front extremities; either for
holding objects, as the squirrel and beaver; or for
digging, as the mole; or for raking the ground, as
the ant-eater and hedgehog55; or for climbing, as the
sloth. Many other animals have, in its place, an
analogous small bone, merely connected to the
muscles56, and called by Vicq-d’Azyr os clavicu-
lare
to distinguish it from the more perfect clavicles.
This is the case with most of the ferae57, and some
glires. Lastly, the form and relative magnitude
of the true articulated clavicles are subject to great
variety. They are excessively long in the bats.
Those of the orang-outang have the greatest re-
semblance to the human subject. In the two-toed
[Seite 45] ant-eater their form is that of a rib: their figure
is most anomalous in the mole, where they are near-
ly cubical. They are entirely wanting in the long-
legged quadrupeds with keel-shaped chest; viz. the
pecora and solidungula; as well as in the cetacea.
(See note (D d) at the end of the chapter).

§ 43. The scapula exists in all red-blooded
animals, which have anterior extremities, or similar
organs of motion: consequently in both classes of
warm-blooded animals without exception. The
form of this bone varies much even in mammalia;
and particularly the relation which its three sides
bear to each other. This depends on the position
of the bone, which is determined by the general
form of the chest. The margin, which is turned to-
wards the spine, is the shortest in most of the proper
quadrupeds; particularly the long-legged ones with
narrow chest; in whom the scapulae lie on the
sides of the chest. In some, as the elephant, the
chiroptera, most of the quadrumana, and especially
in man, this margin is the longest. The scapula
of the mole has a completely anomalous figure,
almost resembling a cylindrical bone. The cora-
coid process, and acromion, the two chief projec-
tions of this bone are strongest in such animals
as have two long clavicles; which might have been
inferred a priori.

[Seite 46]

§ 44. The remarkable varieties of the anterior
extremities, properly so called, may be most con-
veniently considered according to the orders and
genera of animals of this class. The bat and
the mole present the most wide deviations from the
ordinary formation of these parts. The radius59 is
deficient in the fore-arm of the former; or at most
there is only a slender sharp-pointed rudiment of
this bone; their thumb is short, and furnished with
a hook-like nail: the phalanges of the four fingers,
between which the membrane of the wing is ex-
panded, are on the contrary extremely long and
thin, almost like the spines of a fish, and have no
nails. The flying squirrel has a peculiar sharp-
pointed bone at the outer edge of its carpus, con-
nected to that part by means of two small round
bones; and inclosed in the lateral expansion of
the integuments. The form of the os humeri in
the mole is altogether unparalleled; it is thin in
the middle, and surprisingly expanded at either ex-
tremity. The shovel-like paw of this animal is
provided with a peculiar falciform bone; lying at
[Seite 47] the end of the radius. The phalanges of the fin-
gers are furnished with numerous processes; and
have moreover sesamoid bones; all which, by in-
creasing the angle of insertion of the tendons, con-
tributes to facilitate muscular motion. The animals
with divided claws and hoofs have some peculiarities
in the metacarpus and metatarsus. In the pig these
parts consist of four cylindrical bones. In the
pecora before birth, there are two lying close to-
gether; but they are afterwards formed into one
by the absorption of the septum59. The horse has
a single bone (gamba, Vegetius; in French le
canon,
in English the cannon bone or shank bone,)
with a pair of much shorter and immoveable ones,
attached to its posterior and lateral parts, and
firmly united to it, (les poinçons or os epineux, styloid
or splint bones). The main bone only is articulated
to the pastern, which may be compared to the first
phalanx of the human finger; as the coffin bone
resembles in some degree the third60 phalanx;
which supports the nail. This last phalanx is very
various in its form, according to corresponding vari-
ations in its horny coverings; which may consist of
[Seite 48] a flat nail, or claw, or hoof, &c. (See note (E e) at
the end of the chapter).

§ 45. I have something to say respecting the
posterior extremities. The femur of most quadrupeds
is much shorter than the tibia, and hence it hardly
projects from the abdomen. In some few, as the
bear, the femur is longer; this is also the case in
some apes, viz. the orang-outang, in which, as in
several other apes and baboons, the bones of the
arm and fore-arm are surprisingly longer than those
of the thigh and leg. Some, as the elephant, have
no ligamentum teres; consequently there is no
impression made on the head of the thigh bone;
while it is found in others, as the rhinoceros61. The
pecora want the fibula almost universally. The
peculiar form of the astragalus (talus), in the same
order is generally known from the use which the
ancients62 made of the bone in their celebrated
game. In some quadrumana, as the orang outang,
[Seite 49] the two posterior phalanges of their toes are re-
markably curved in their shape; which enables
them to hold the branches of trees more firmly,
and is in the same degree unfavourable to the per-
formance of progression in an erect position. Ce-
taceous animals have no bones in their tail fins,
but they have a bony compages in their thoracic
fins, which completely resembles the front extre-
mities of the seal63. See note (F f) at the end of
the chapter.


Additional Notes to the Second Chapter.

(A) The bones of the head, in birds, are joined
either by the squamous kind of suture; or by the
mere apposition of their margins: which species
of union is termed harmonia. But they are soon
consolidated into a single piece.

(B) The sphenoid bone is often divided into two
parts in the quadrumana; one of these forms the
lesser alae, and anterior clinoid processes; the
[Seite 50] greater alae, the posterior clinoid processes, and
basilar fossa are formed by the other portion.

The two parietal bones form a single piece in
the bat-kind. The same circumstance occurs in
the carnivora, in the pig, tapir, hippopotamus, and
horse.

The frontal and parietal bones of the elephant
become consolidated, at an early period, with all
the other parts of the cranium; so as to form a
bony cavity, in which no trace of sutures can be
discerned. The parietal, occipital, and temporal
bones are likewise soon joined into one piece in
the cetacea.

The pig, hippopotamus, tapir, horse, seal, walrus,
and the rodentia have the os frontis divided by a
middle suture into two portions.

That portion of the os temporis, which contains
the tympanum, is separated from the rest of the
bone by a suture, in the dog, cat, and horse; also
in the ruminantia and rodentia. It is so com-
pletely separated in the cetacea, as to be attached to
the cranium only by soft parts. In the elephant,
where the other bones are consolidated into one
piece, this remains distinct.

The cranium of the mammalia possesses the same
fossae at its basis, as are found in the human sub-
ject: they are however much shallower; and the
eminences, which define them, are much less
strongly marked than in man. This difference is
very perceptible even in the simiae, where the cavi-
[Seite 51] ties which hold the cerebellum, are nearly on a
level with the middle fossae of the basis cranii; and
the sella turcica is more superficial. The same fact
is more strongly marked as we arrive at those
animals, whose general structure deviates more
considerably from that of man. Those mammalia,
which have the occipital foramen situated at the back
of the head, must have the fossae cerebelli moved
upwards; hence that margin of the fossae, which
is posterior in man, passes across the upper part
of the back of the head in these animals. The
bony projections, which bound this fossa in some
mammalia, are described in the chapter on the
brain.

The optic foramina of the elephant commence
from one canal, which receives the two optic
nerves.

The foramen rotundum is sometimes absent, its
place being supplied by the spheno-orbitary fissure,
(foramen lacerum) e.g. in the elephant and horse.
The foramen ovale is also frequently wanting; being
included perhaps in the vacancy left between the pe-
trous portion of the temporal bone, and the body
of the sphenoid. This latter opening does not exist
in the genus simia, nor in the carnivorous mammalia,
nor in the ruminantia. It is on the contrary very
large in the elephant, and in some rodentia.

The carotid canal does not exist in the rodentia;
but the artery enters at the opening between the
sphenoid and temporal bones.

[Seite 52]

The structure of the cranium presents a very re-
markable singularity in the elephant. Its two tables
are separated from each other to a considerable
extent, by numerous bony processes; between
which are formed a vast number of cells, com-
municating with the throat by means of the
eustachian tube, and filled with air, instead of the
bloody or medullary substance, which occupies the
diplöe of animals. The use of this structure in
increasing the surface for attachment of those large
muscles, which belong to the lower jaw, proboscis
and neck; and in augmenting the mechanical
power of these muscles by removing their attach-
ments to a greater distance from the centre of
motion has been very ingeniously explained by
Camper (Oeuvres, tom. 2). These advantages
are attained by the cellular structure, which we
have just described, without augmenting the weight
of the head, and this precaution is particularly
necessary in the present instance, as the head is
on other accounts more heavy and massy in this
than in any other animal. The air cells of birds
in general, and particularly those which pervade
the cranium in the ostrich, eagle, and owl presents
examples of a similar formation, attended with the
same uses; viz. those of increasing the bulk and
strength of the bone, and diminishing its weight.

(C) The crista occipitalis is a sharp and pro-
minent bony ridge, projecting from the upper and
[Seite 53] back part of the cranium in mammalia, chiefly for
the attachment of the temporal muscle.

The size of the temporal fossa, depends upon the
magnitude of the muscle, which it contains. Hence
it is larger in the carnivora than in any other or-
der; not only occupying the whole sides and upper
part of the cranium, but being still further increased
by prominent bony cristae, growing from the frontal,
parietal, and occipital bones. The two temporal
muscles are indeed separated in many of these ani-
mals, merely by the parietal ridge, which would
completely cover the cranium.

These ridges are not so strongly marked in any
animals, as in the carnivora: yet they are discern-
ible in most of the simiae. They occur also in ani-
mals of the pig kind, and in the other pachydermata.

The occipital crista is found where the others do
not exist; as it serves for the attachment of the
muscles of the neck.

(D) The variations in the situation of the occi-
pital foramen are important, when viewed in con-
nexion with the ordinary position of the animal’s
body. In man, who is designed to hold his body
erect, this opening is nearly equi-distant from the
anterior and posterior extremities of the skull. The
head therefore is supported in a state of equilibrium
on the vertebral column. The angle, formed by
the two lines mentioned by Daubenton, is only
of three degrees.

[Seite 54]

Quadrupeds, which go on all-fours, have the oc-
cipital foramen and condyles situated farther back,
in proportion as the face is elongated. That open-
ing, instead of being nearly parallel to the horizon,
forms a considerable angle with it; which, mea-
sured, according to Daubenton, is of 90 degrees
in the horse. The weight of the head in these ani-
mals, is not therefore sustained by the spine; but
by a ligament of immense strength, which is either
entirely deficient, or so weak, as to have its exist-
ence disputed in the human subject. This ligamen-
tum nuchae,
or cervical ligament, arises from the spines
of the dorsal and cervical vertebrae, (which are re-
markably long for that purpose) and is fixed to the
middle and posterior part of the occipital bone.
It is of great size and strength in all quadrupeds,
but most particularly in the elephant; where the vast
weight of the head, so much increased by the enor-
mous size of the tusks, sufficiently accounts for its in-
creased magnitude. It is bony in the mole, probably
on account of the use, which the animal makes of
its head, in disengaging and throwing up the earth.

Animals of the genus simia and lemur hold a
middle rank between man, who is constantly erect,
and quadrupeds, whose body is supported by four
extremities. Their structure is by no means cal-
culated, like that of man, for the constant mainte-
nance of the erect posture; but they can support it
with greater facility, and for a longer time than
other animals. Hence, in the orang-outang, the
[Seite 55] occipital foramen is only twice as far from the jaws
as from the back of the head, so that Daubenton’s
angle is only of 37°. It is somewhat larger in the
other species of simiae; and measures 47° in the
lemur.

(E) The two organs, which occupy most of the
face, are those of smelling and tasting (including
those of mastication, &c.). In proportion, as these
parts are more developed, the size of the face,
compared to that of the cranium, is augmented.
On the contrary, when the brain is large, the vo-
lume of the cranium is increased in proportion to
that of the face. A large cranium and small face
indicate therefore a large brain, with inconsiderable
organs of smelling, tasting, masticating, &c.; while
a small cranium, with a large face, shew that these
proportions are reversed.

The nature and character of each animal must
depend considerably on the relative energy of its
different functions. The brain is the common
centre of the nervous system. All our perceptions
are conveyed to this part, as a sensorium commune:
and this is the organ, by which the mind combines
and compares these perceptions, and draws infer-
ences from them; by which, in short, it reflects and
thinks. We shall find, that animals partake in a
greater degree of this latter faculty, or at least ap-
proach more nearly to it, in proportion as the mass
of medullary substance, forming their brain, exceeds
[Seite 56] that, which constitutes the rest of the nervous sys-
tem; or, in other words, in proportion as the or-
gan of the mind exceeds those of the senses. Since
then, the relative proportions of the cranium and
face, indicate also those of the brain, and the two
principal external organs, we shall not be surprized
to find, that they point out to us, in great measure,
the general character of animals; the degree of
instinct and docility which they possess. Man com-
bines by far the largest cranium, with the smallest
face; and animals deviate from these relations, in
proportion as they increase in stupidity and fe-
rocity.

One of the most simple methods (though some-
times indeed insufficient), of expressing the relative
proportions of these parts, is by means of the facial
line, which has been already described. This angle
is most open, or approaches most nearly to a right
angle in the human subject; it becomes constantly
more acute, as we descend in the scale, from man;
and in several birds, reptiles, and fishes, it is lost
altogether, as the cranium and face, are completely
on a level. The idea of stupidity is associated, even
by the vulgar, with the elongation of the snout:
hence the crane and snipe have become proverbial.
On the contrary, when the facial line is elevated by
any cause, which does not increase the capacity of
the cranium, as in the elephant and owl, by the
cells, which separate the two tables, the animal ac-
quires a particular air of intelligence, and gains the
[Seite 57] credit of qualities, which he does not in reality pos-
sess. Hence the latter animal has been selected as
the emblem of the goddess of wisdom. The in-
valuable remains of Grecian art shew, that the
ancients were well acquainted with these circum-
stances: they were aware, that an elevated facial
line formed one of the grand characters of beauty;
and indicated a noble and generous nature. Hence
they have extended the facial angle to 90 degrees
in the representation of men, on whom they wished
to bellow an august character. And in the repre-
sentations of their gods and heroes, they have even
carried it beyond a right angle, and made it 100°.

It must, however, be allowed, that the facial an-
gle is of chief importance in its application to the
cranium of the human subject, and of the quadru-
mana;
as various circumstances affect the conclu-
sions, which would result from employing it in other
classes of mammalia. Thus in the carnivorous, and
some of the ruminating animals; in the pig, and
particularly in the elephant, the great size of the
frontal sinuses produces an undue elevation of the
facial line. In many of the rodentia, as the hare,
&c., the nose occupies so large a space, that the
cranium is thrown quite back, and presents no point
on a front view, from which this time can be
drawn.

The following are the angles formed, by drawing
a line along the floor of the nostrils, and intersecting
it by another, which touches the anterior margin
[Seite 58] of the upper alveoli, and the convexity of the cra-
nium (whether the latter point be concealed by the
face, or no).

European infant 90°
––––––– adult 85
Adult negro 70
Orang-outang 67
Long-tailed monkies 65
Baboons 40 to 30
Pole-cat 31
Pug dog 35
Mastiff; the line passing along the
outer surface of the skull

41
D° inner d° 30
Leopard; inner surface 28
Hare 30
Ram 30
Horse 23
Porpoise 25

In the 3d and 4th tables of Cuvier’s Tableau
Elementaire de l’Histoire Naturelle,
the crania of se-
veral mammalia are represented in profile; so as to
afford a sufficient general notion of the varieties in
the facial angle. A similar comparative view, in
one plate, is given by White, in his account of the
Regular Gradation, &c. from the work of Camper.

A vertical section of the head, in the longitudinal
direction, shews us more completely the relative
proportions of the cranium and face. In the
European, the area of the section of the cranium is
[Seite 59] four times as large as that of the face; the lower
jaw not being included. The proportion of the
face is somewhat larger in the negro: and it in-
creases again in the orang-outang. The area of the
cranium is about double that of the face in the
monkeys: in the baboons, and in most of the carni-
vorous mammalia,
the two parts are nearly equal.
The face exceeds the cranium in most of the other
classes. Among the rodentia, the hare and marmot
have it one-third larger; in the porcupine, and the
ruminantia, the area of the face is about double that
of the cranium; nearly triple in the hippopotamus;
and almost four times as large in the horse. In
reptiles and fishes, the cranium forms a very in-
considerable portion of the section of the head;
although it is considerably larger than the brain,
which it contains.

The outline of the face, when viewed in such a
section, as we have just mentioned, forms in the
human subject a triangle; the longest side of which
is the line of junction between the cranium and
face. This extends obliquely backwards and down-
wards, from the root of the nose, towards the fora-
men occipitale. The front of the face, or the
anterior line of the triangle, is the shortest of the
three. The face is so much elongated, even in the
simiae, that the line of junction of the cranium and
face is the shortest side of the triangle; and the
anterior one the longest. These proportions be-
come still more considerable in other mammalia.

[Seite 60]

(F) The want of the os intermaxillare has been
regarded as a chief characteristic of the human sub-
ject; as one of the leading circumstances, which
distinguish man from other mammalia. That this
bone is really wanting in man must be allowed,
notwithstanding the doubts of Vicq d’Azyr. The
well-known transverse slit, behind the alveoli of the
incisors in the human foetus, would form a very
slight and remote analogy between the human
structure, and that of animals: and, when we con-
sider, that the superior or facial surface of the max-
illary bones, so far from being marked by any suture,
does not even bear a slit like that of the inferior
part, it must be put entirely out of the question.

That all other mammalia possess this bone, is not
quite so clear, as that man has it not. The excep-
tions occur in the quadrumana. In addition to
those which the author has stated, it may be ob-
served, that the head of an orang-outang, in the
Hunterian Museum, which possesses all the other
sutures, wants those, which separate the intermaxil-
lary bone: that Tyson did not find this bone in his
specimen of the animal, which was very young,
(see his Anatomy of the Pigmy) and that it did not
exist in a cranium, which was delineated by Dau-
benton.
I have also seen the crania of other
monkeys, where the other sutures were all perfect
and distinct, which did not possess this bone.

(G). The zygoma is wanting in the ant-eater;
[Seite 61] where the temporal and molar bones have only a
slight projection instead of the usual zygomatic pro-
cess. This circumstance is sufficiently explained by
the want of teeth, and the consequent want of mas-
tication. The zygomatic suture is so oblique in the
carnivora, that the temporal bone forms the whole
superior margin; and the os malae, the inferior
edge of the zygoma.

The zygoma may be arched both in the vertical
and horizontal directions. A curvature of the lat-
ter kind indicates the existence of a strong temporal
muscle; while one of the former description shews
that the masseter is large. Both these curvatures
are considerable in the carnivora.

(H) The interval between the orbits is always
smaller in the simiae than in the human subject.
In several of these, as in the monkeys, properly so
called, the two orbits are separated at their posterior
part by a simple bony septum. In other mam-
malia, these cavities are thrown towards the side of
the head, and to a great distance from each other,
by the ascending or nasal processes of the upper
jaw-bones, which are very large.

In those mammalia, which have the orbit open
at its outer and back part, so as to communicate
with the temporal fossa, (such as the carnivora, ro-
dentia, edentata,
and pachydermata) the os malae
merely contributes to the formation of the zygoma,
without being connected to the frontal or sphenoid
[Seite 62] bones. The superior maxilla merely forms the
anterior border of the cavity, without constituting
the floor of the orbit, which is indeed open below.
The ossa palati, which are large, form a considerable
share of the inner part of the cavity; the ethmoid
bone not contributing to it.

The ruminating animals, as well as the horse and
ass, have the margin of the orbit completed at its
outer part by a bony circle, although the cavity is
open behind to the temporal fossa.

The mole has not, properly speaking, an orbit.
Its diminutive eyes, the very existence of which, was
for a long time questioned, lie under the integu-
ments. Blumenbach’s Description of the Bones,
in German, p. 225. note. The same observation
holds good of the myrmecophuga didactyla. Ibid.

(I) The word horn, which is frequently applied
in English to the antlers of the deer kind, as well
as to the real horns of other genera, would lead to
a very erroneous notion on this subject. The ant-
ler
is a real bone; it is formed in the same manner,
and consists of the same elements as other bones;
its structure is also the same.

It adheres to the frontal bone by its basis; and
the substance of the two parts being consolidated
together, no distinction can be traced, when the
antler is completely organized. But the skin of
the forehead terminates at its basis, which is marked
by an irregular projecting bony circle; and there
is neither skin nor periosteum on the rest of it.
[Seite 63] The time of its remaining on the head is one year:
as the period of its fall approaches, a reddish mark
of separation is observed between the process of the
frontal bone, and the antler. This becomes more
and more distinctly marked, until the connection
is entirely destroyed.

The skin of the forehead extends over the process
of the frontal bone, when the antler has fallen: at
the period of its regeneration, a tubercle arises from
this process, and takes the form of the future antler,
being still covered by a prolongation of the skin.
The structure of the part at this time is soft and
cartilaginous; it is immediately inverted by a true
periosteum, containing large and numerous vessels,
which penetrate the cartilage in every direction, and
by the gradual deposition of ossific matter, convert
it into a perfect bone.

The vessels pass through openings in the pro-
jecting bony circle at the base of the antler:
the formation of this part, proceeding in the same
ratio with that of the rest, these openings are
contracted, and the vessels are thereby pressed, until
a complete obstruction ensues. The skin and pe-
riosteum then perish, become dry and fall off; the
surface of the antler remaining uncovered. At the
stated period it falls off, to be again produced, al-
ways increasing in size.

(K) As the motions of the lower jaw must be
materially influenced by the form of its condyle,
[Seite 64] and by the manner in which that process is con-
nected to the articular cavity of the temporal bone;
we shall find, as might have been expected, a close
relation between these circumstances, and the kind
of food, by which an animal is nourished, Thus
the lower jaw of the carnivora can only move up-
wards and downwards, and is completely incapable
of that horizontal motion, which constitutes ge-
nuine mastication. Hence these animals cut and
tear their food in a rude and coarse manner, and
swallow it in large portions, which are afterwards
reduced by the solvent properties of the gastric
juice. Such mammalia, on the contrary, as live on
vegetables, have, in addition to this motion, a power
of moving the lower jaw backwards and forwards,
and to either side; so as to produce a grinding ef-
fect, which is necessary for bruising and triturating
grass, and for pulverising and comminuting grains.
In all these, therefore, the form of the condyle, and
of its articular cavity, allows of free motion in almost
every direction. The teeth may be compared, in
the former case, to scissars; in the latter, to the
stones of a mill.

(L) The teeth of the human subject seem to be
designed for the single purpose of mastication; and
hence an erroneous conclusion might be drawn,
that they serve the same office in other animals.
Many exceptions, however, must be made to this
general rule. Some mammalia, which have teeth
[Seite 65] for the office of mastication, have others, which can
be only considered as weapons of offence and de-
fence, viz. the tusks of the elephant, hippopotamus,
walrus,
and manati. The large and long canine
teeth of the carnivora, as the lion, tiger, dog, cat,
&c. not only serve as natural weapons to the ani-
mal, but enable it to seize and hold its prey, and
assist in the rude laceration which the food under-
goes previous to deglutition. The seal, the porpoise,
and other cetacea, as the cachalot (physeter macroce-
phalus
) have all the teeth of one and the same
form; and that obviously not calculated for masti-
cation. They can only assist in securing the prey,
which forms the animal’s food.

(M) Animals of the genus baloena (the proper
whales) have, instead of teeth, the peculiar sub-
stance called whalebone, covering the palatine sur-
face of the upper jaw: this resembles in its com-
position hair, horn, and such matters.

The lower surface of the upper jaw forms two
inclined plants, which may be compared to the roof
of a house reversed; but the two surfaces are con-
cave. Both these are covered with plates of the
whalebone, placed across the jaws, and descending
vertically into the mouth. They are parallel to
each other, and exist to the number of two or three
hundred on each of the surfaces. They are con-
nected to the bone by the intervention of a white
ligamentous substance, from which they grow;
[Seite 66] but their opposite edge, which is turned towards
the cavity of the mouth, has its texture loosened
into a kind of fringe, composed of long and slender
fibres of the horny substance; which therefore
covers the whole surface of the jaw. This struc-
ture probably serves the animal in retaining and
confining the mollusca, which constitute its food.

The teeth of the ornithorhynchus paradoxus and
hystrix deviate very considerably from those of
other mammalia. In the former animal there is
one on each side of the two jaws: it is oblong,
flattened on its surface, and consists of a horny
substance adhering to the gum. There are like-
wise two horny processes on the back of the
tongue: these point forwards, and are supposed by
Mr. Home to prevent the food from passing into
the fauces, before it has been sufficiently masticated.
In the o. hystrix, there are six transverse rows of
pointed horny processes at the back of the palate;
and about twenty similar horny teeth on the cor-
responding part of the tongue.

Mr. Home in the Philos. Trans. 1800, part 2.
1802, parts 1 and 2.

(N) The substance composing these tusks, and
commonly called ivory, is certainly different from
the bone of other teeth. It is, generally speaking,
more hard and compact in its texture. The ivory
of the elephant’s tusk is distinguished from all
others by the curved lines, which pass in different
[Seite 67] directions from the centre of the tooth, and form
by their decussation, a very regular arrangement
of curvilinear lozenges. It soon turns yellow from
exposure to the air. The tusk of the hippopota-
mus is harder and whiter; and consequently pre-
ferred for the formation of artificial teeth. In the
walrus, the interior of the tooth is composed of
small round portions, placed irregularly in a sub-
stance of different appearance, like the pebbles in
the pudding stone; and the molar teeth have a
similar structure.

(O) The facts, which the author has here re-
counted, have been some times brought forwards
in order to prove the vascularity of the teeth; a
doctrine, which is refuted by every circumstance
in the formation, structure, and diseases of these
organs. It may be first observed, that the ap-
pearances exhibited by the teeth in question, are
by no means what we should reasonably expect in
such a case. When a bullet has entered the sub-
stance of the body, the surrounding lacerated and
contused parts do not grow to the metal, and be-
come firmly attached to its surface, but they in-
flame and suppurate in order to get rid of the
offending master. If the ivory be vascular and
sensible, why do not the same processes take place
in it?

We can explain very satisfactorily how a bullet
may enter the tusk of an elephant, and become
[Seite 68] imbedded in the ivory without any opening for
its admission being perceptible. It will be shewn
in a subsequent note, that these tusks are constantly
growing during the animal’s life, by a deposition
of successive laminae within the cavity, while the
outer surface and the point are gradually worn
away: and that the cavity is filled for this purpose
with a vascular pulp, similar to that, on which
teeth are originally formed. If a ball penetrate
the side of a tusk, cross it cavity, and lodge in
the slightest way on the opposite side, it will be-
come covered towards the cavity by the newly
deposited layers of ivory, while no opening will
exist between it and the surface, to account for its
entrance. If it have only sufficient force to enter,
it will probably sink, by its own weight, between
the pulp and tooth, until it rests at the bottom of
the cavity. It there becomes surrounded by new
layers of ivory; and as the tusk is gradually worn
away, and supplied by new depositions, it will
soon be found in the centre of the solid part of the
tooth. Lastly, a foreign body may enter the tusk
from above, as the plate of bone, which forms its
socket is thin; if this descends to the lower part
of the cavity, it may become imbedded by the
subsequent formations of ivory. This must have
happened in a case where a spear-head was found
in an elephant’s tooth. The long axis of the
foreign body corresponded to that of the cavity.
No opening for its admission could be discovered,
[Seite 69] and it is very clear, that no human strength could
drive such a body through the side of a tusk.
Philos. Trans. 1801. part 1.

(P) The front teeth are the incisores, or cutting-
teeth;
the primores of Linnaeus. The corner teeth
are the canini; laniarii of Linnaeus; cuspidati of
Mr. Hunter. The back teeth are the Molares
or grinders. The term of tusks is applied to such
teeth as extend out of the cavity of the mouth.

(Q) The structure of the incisor teeth, in the
rodentia, deserves attention on several accounts.
They are covered by enamel only on their anterior
or convex surface, and the same circumstance holds
good with respectto the tusks of the hippopotamus.
Hence as the bone wears down much faster than
this harder covering, the end of the tooth always
constitutes a sharp cutting edge, which renders it
very deserving of the name of an incisor tooth.

This partial covering of enamel refutes, as
Blake has observed (Essay on the Structure, &c.
of the Teeth,
p. 212), the opinion that the enamel
is formed by the process of crystallization.

The incisor teeth of these animals are used in
cutting and gnawing the harder vegetable sub-
stances; for which their above-mentioned sharp
edge renders them particularly well adapted.
Hence Cuvier has arranged these animals in a
[Seite 70] particular order by the name of rodentia, or the
gnawers. As this employment subjects the teeth
to immense friction, and mechanical attrition, they
wear away very rapidly, and would soon be con-
sumed, if they did not possess a power of growth,
by which this loss is recompenced.

These teeth, which are very deeply imbedded in
the jaw, are hollow internally, just like a human
tooth, which is not yet completely formed. Their
cavity is filled with a vascular pulp, similar to that
on which the bone of a tooth is formed; this
makes a constant addition of new substance on
the interior of the tooth, which advances to sup-
ply the part worn down. The covering of enamel
extends over that part of the tooth, which is con-
tained in the jaw, as we might naturally expect:
for this must be protruded at some future period
to supply the loss of the anterior portion. Although
these teeth are very deeply implanted in the max-
illary bones, they can hardly be said to possess a
fang or root; for the form of the part is the same
throughout; the covering of enamel is like-
wise continued; and that part, which at one period
is contained in the jaw, and would form the fang,
is afterwards protruded to constitute the body of
the tooth.

The constant growth of these teeth therefore
proceeds in the same manner, and is effected on
the same principles as the original formation of any
[Seite 71] tooth; and can by no means furnish an argument
for the existence of vessels in the substance of the
part.

We cannot help being struck with the great
size of these teeth, compared with the others of the
same animal, or even with the bulk of the animal.
Their length in the lower jaw nearly equals that
of the jaw itself, although a small proportion only
of this length appears through the gum. They
represent the segment of a circle; and are con-
tained in a canal of the bone, which descends un-
der the sockets of the grinders, and then mounts
up, in some instances, to the root of the coronoid
process: hence although their anterior cutting
edge is in the front of the mouth, the posterior
extremity is behind all the grinding teeth. No
animal exhibits this structure better than the rat.
The beaver also affords a good specimen of it on a
larger scale. It has been drawn in this animal by
Blake, (Essay on the Structure, &c. of the Teeth,
tab. 9. fig. 3.) The tooth does not extend so far
in the upper jaw; it is there implanted in the inter-
maxillary bone, and terminates over the first
grinder.

The observations which have been made respect-
ing the constant growth of the incisor teeth of the
glires, will apply also to the tusks of the elephant.
These are hollow internally, through the greater
part of their length, and the cavity contains a vas-
cular pulp, which makes constant additions of suc-
[Seite 72] cessive layers, as the tusk is worn down. One of
the elephants at Exeter Change is said to have
nearly bled to death from a fracture of the tusk,
and consequent laceration of the vessels of the
pulp. The tusks of the hippopotamus, and probably
all other teeth of this description grow in the same
manner. Farther and more accurate observation
may hereafter shew, that the same mode of growth
obtains also in other classes of teeth, when they are
exposed to great friction. Something similar may
certainly be observed in the grinders of the horse.
The tooth is not finished when it cuts the gum:
the lower part of its body is completed while the
upper part is being worn away in mastication; and
the proper fang is not added till long after. Hence
we can never get one of these teeth in a perfect
state, for if the part out of the gum is complete,
the rest of the body is imperfect; and there are
no fangs: on the contrary, when the fangs are
formed, much of the body has been worn away in
mastication. Blake also asserts that this structure
is found in the grinders of the beaver, p. 99.
tab. 9. fig. 4.

(R) This animal is found so constantly with
only one tusk, that it has been called in common
language, the sea-unicorn; and Linnaeus has even
given it a similar appellation, that of monodon. Yet
there can be no doubt that it possesses originally
two of these; one in either jaw bone: and that
[Seite 73] which is wanting, must have been lost by some
accidental circumstance, as we can easily suppose,
(Shaw’s Zoology, vol. ii. p. 473.) These tusks
often equal in length that of the animal’s body;
which may be 18 feet or more: yet they are
always slender.

(S) The distribution of the enamel, and bony
substance, varies in the teeth of different animals,
and even in the different orders of teeth in the
same animal.

All the teeth of the carnivora, and the incisors
of the ruminating animals, have the crown only
covered with enamel, as in the human subject.
The immense fossil grinders of the animal incogni-
tum
or mammoth have a similar distribution of this
substance.

The grinders of graminivorous quadrupeds, and
the incisors also of the horse have processes of ena-
mel, descending into the substance of the tooth.
These organs have also in the last-mentioned ani-
mals a third component part, differing in ap-
pearance from both the others, but resembling
the bone more than the enamel. Blake has dis-
tinguished this by the name of crusta petrosa;
and Cuvier calls it cement.

The physiological explanation of this difference
in structure is a very easy and clear one. The food
of the carnivora requires very little comminution
before it enters the stomach: hence the form of
[Seite 74] their grinding teeth is by no means calculated for
grinding; and as the articulation of the jaw ad-
mits no lateral motion, the molares, of which the
lower are overlapped by the upper, can only act
like the incisors of other animals. The food of
graminivorous quadrupeds is subject to a long
process of mastication, before it is exposed to the
action of the stomach. The teeth of the animals
suffer great attrition during this time, and would be
worn down very rapidly but for the enamel, which
is intermixed with their substance. As this part is
harder than the other constituents of the teeth, it
resists the attrition longer, and presents the ap-
pearance of prominent ridges on the worn surface,
by which the grinding of the food is much facili-
tated.

The distinction of the three substances is seen
better in the tooth of the elephant than in any
animal. The best method of displaying it is by
making a longitudinal vertical section, and polish-
ing the cut surface. The crusta petrosa will then
be distinguished by a greater yellowness and opacity
in its colour; and by an uniformity in its ap-
pearance, as no laminae or fibres can be distin-
guished.

The pulp of a grinding tooth of a graminivorous
quadruped is divided into certain conical processes,
which are united at their bases. These vary from
two to six in the horse and cow. On these the bone
of the tooth is formed, as on the single pulp of the
[Seite 75] human subject, but it is here divided into as many
separate shells, as there are processes of the pulp:
all of them however inclosed in a common capsule.
The ossification commences, as in all teeth, on the
points of the pulp, and extends towards the basis:
when it has arrived there, the shells unite together;
and they also join at their outer margins. Between
the processes of the pulp other productions descend
from the capsule in a contrary direction; and
deposit, on the surface of the shells, enamel dis-
tinguishable by its crystalline appearance, and hence
denominated by Blake cortex striatus. When
these membranous productions have formed their
portions of enamel, they secrete the crusta petrosa
within the cavities left between these productions of
enamel. The outer surface of the bone of the
tooth is covered by enamel, which may be com-
pared to that which invests the crown of a human
tooth, except that it is deposited in an irregular
waving line, in order to render the surface better
calculated for grinding: and the inequalities of
this surface of enamel are filled up by crusta petrosa.
The exterior enamel, and crusta petrosa, (which
may be so named, by way of distinguishing them
from the processes within the tooth), are formed by
the surface of the capsule.

If then we make a transverse section of a grind-
ing tooth of the horse or cow, the exterior surface
will be found to consist of an irregular layer of
crusta petrosa: this is succeeded by a waving line
[Seite 76] of enamel, within which is the proper bone of the
tooth.
But the substance of the latter is penetrated
by two productions of enamel; in the interior of
each of which is crusta petrosa.

The crusta petrosa which fills these internal pro-
ductions of enamel, is sometimes not completely
deposited before the tooth cots the gum: hence
cavities are left in the centre of the tooth, which
become filled with a dark substance composed of
the animal’s food, and other foreign matters. This
seldom happen to any considerable extent in the
grinders of the horse. In the cow and sheep these
cavities are constantly filled with the dark adven-
titious matter; the crusta petrosa being confined to
the exterior surface of the tooth, and not existing
even there so plentifully as in the horse.

The lower grinders of the horse differ very
much in their formation from those of the upper-
jaw. Ossification commences in these by four or
five points, which increase into as many small
shells; yet they unite without any processes of
the capsule passing down between to form internal
productions of the enamel. This substance is
however deposited in a very convoluted manner on
the bone of the tooth, so that the same end is
attained, as if productions of the cortex striatus
had existed in the centre of the part. The crusta
petrosa fills up the irregularities of this waving line
of enamel. An horizontal section of such a tooth
presents the three substances arranged within each
[Seite 77] other: the crusta petrosa is external; then comes
the enamel, which includes nothing but the proper
bone of the tooth.

The incisors of the horse have a production of
enamel in their centre; but the cavity, which this
forms, containing no crusta petrosa, is merely filled
by the particles of food, &c. As these processes of
enamel descend only to a certain extent in the
tooth, they disappear at last from the constant
wear of the part in mastication. This is improperly
called the filling up of the teeth; and hence a
criterion arises of the horse’s age.

The grinding teeth of the elephant contain the
most complete intermixture of the three substances;
and have a greater proportion of crusta petrosa,
than those of any other animal. The pulp forms
a number of broad flat processes, lying parallel to
each other, and placed transversely between the
inner and outer laminae of the alveoli. The bone of
the tooth is formed on these in separate shells, com-
mencing at their loose extremities, and extending to-
wards the basis, where they are connected together.
The capsule sends an equal number of membranous
productions; which first cover the bony shells with
enamel, and then invests them with crusta petrosa;
which latter substance unites and consolidates the dif-
ferent portions. The bony shells vary in number
from four to twenty-three, according to the size of
the tooth, and the age of the animal: they have been
described under the term of denticuli, and have
[Seite 78] been represented as separate teeth in the first in-
stance. It must however be remembered that they
are formed on processes of one single pulp.

When the crusta petrosa is completely deposited,
the different denticuli are consolidated together.
The bony shells are united at their base to the
neighbouring ones; the investments of enamel are
joined in like manner: and the intervals are filled
with the third substance, which really deserves the
name bestowed on it by Cuvier, of cement. The
pulp is then elongated for the purpose of forming
the roots or fangs of the tooth. From the peculiar
mode of dentition of this animal, which will be
explained in a subsequent note, the front portion
of the tooth has cut the gum, and is employed in
mastication, before the back part is completely
formed, even before some of the posterior denticuli
have been consolidated. The back of the tooth
does not appear in the mouth until the anterior part
has been worn down even to the fang.

A horizontal section of the elephant’s tooth pre-
sents a series of narrow bands of bone of the tooth,
surrounded by corresponding portions of enamel.
Between these are portions of crusta petrosa; and
the whole circumference of the section is composed
of a thick layer of the same substance.

A vertical section in the longitudinal direction
exhibits the processes of bone, upon the different
denticuli, running up from the fangs; a vertical
layer of enamel is placed before, and another behind
[Seite 79] each of these. If the tooth is not yet worn by mas-
tication, the two layers of enamel are continuous at
the part, where the bone terminates in a point;
and the front layer of one denticulus is continuous
with the back layer of the succeeding one, at the
root of the tooth; so that the enamel, ascending on
the anterior, and descending on the posterior sur-
face of each denticulus, forms a continued line
through the whole tooth. Crusta petrosa intervenes
between the ascending and descending portions of
the enamel.

As the surface of the tooth is worn down in mas-
tication, the processes of enamel, resisting by their
superior hardness, form prominent ridges on the
grinding surface; which must adapt it excellently
for bruising and comminuting any hard substance.

The grinding bases, when worn sufficiently to
expose the enamel, present a very different appear-
ance in the Asiatic and African elephants. The
processes of enamel, in the former species, represent
flattened ovals, placed across the tooth. In the
latter, they form a series of lozenges, which touch
each other in the middle of the tooth.

It does not appear, that crusta petrosa is an essen-
tial part in the grinders of graminivorous animals.
For those of the rhinoceros do not possess it, although
the enamel descends into their substance, and forms
a cavity, which is filled with the food, &c.

Home and Blake likewise state, that it does not
exist in the hippopotamus, where there are internal
[Seite 80] productions of enamel: but Mr. Macartney,
the learned and ingenious lecturer on comparative
anatomy at St. Bartholomew’s Hospital, has found
it in small quantity on the exterior surface of the
tooth, near its root.

Mr. Corse’s Observations on the different Species
of Asiatic Elephants.
Philos. Trans. 1799, part 2.

Some Observations on the Teeth of graminivorous
Quadrupeds, by
E. Home, Esq. Ibid. With De-
lineations of the Teeth of the Elephant, Horse, Cow,
Sheep, Hippopotamus,
and Rhinoceros.

Blake’s Essay on the Structure and Formation
of the Teeth in Man, and various Animals,
with
plates.

Tenon sur une Methode particuliere d’etudier
l’Anatomie,
in the Memoires de l’lnstitut National,
tome 1, an. 6.

Cuvier, Léçons d’Anatomie comparée, tome 3.

(T) All the three kinds of teeth are found in
the quadrumana, the carnivora, the pachydermata
(excepting the two horned rhinoceros and elephant),
the horse, and those ruminating animals, which have
no horns.

Cuvier states, that the teeth of an animal, whose
bones are found in a fossile state, resemble those of
man, in being arranged in a continued and un-
broken series.

In the simiae, carnivora, and all such as have ca-
nines longer than the other teeth, there is at least
[Seite 81] one vacancy in each jaw, for lodging the cuspidatus
of the opposite jaw. There is a vacancy behind
each canine in the bear.

The horned ruminating animals not only want
entirely the upper incisors, but they are also destitute
of cuspidati, except the stag, which has rudiments
of these teeth; and the musk (moschus moschifer)
where they are very long, and curved in the upper
jaw.

Between the incisors and grinders of the horse, a
very large vacancy is left, in the middle of which a
small canine tooth, termed the tush, is found in the
male animal; but very rarely in the female.

The elephant has grinders and two tusks in the
upper jaw; but the former only in the lower. The
immense tusks belong properly to the male animal:
as they are so small in the female, generally speaking,
as not to pass the margin of the lip. (Corse in
Phil. Trans. 1799, part 2. p. 208.)

The sloths have grinding and canine teeth, with-
out incisors. The dolphin and porpoise have small
conical teeth, all of one size and shape, arranged
in a continued line throughout the alveolar margin
of both jaws. The cachalot (Physeter macrocepha-
lus
) has these in the lower jaw only. The teeth of
the seal are all of one form, viz. that of the canine
kind; conical and pointed.

The narwhal has no other teeth than the two long
tusks implanted in its os intermaxillare; of which
one is so frequently wanting. A head, in which
[Seite 82] there are two of these tusks, is delineated by Dr.
Shaw, in his Zoology, from a specimen in the
Leverian Museum. These tusks are remarkable
for the spirally convoluted appearance of their ex-
ternal surface. They are hollow internally, and
probably have a constant growth like the elephant’s
tusks.

(U) The permanent teeth are generally formed
in cavities near the roots of the temporary ones;
and they succeed to the vacancies left by the dis-
charge of the latter.

A different mode of succession obtains, however,
in some instances. The adult molares of the hu-
man subject are not formed near any of the tem-
porary teeth; but in the back of the two jaws;
from which situation they advance successively to-
wards the front, in proportion as the maxillary
bones are lengthened in that direction. A similar,
but much more remarkable species of succession is
observed in the grinders of the elephant, where it
was ascertained by the labours of Mr. Corse, who
has explained and illustrated the subject, in a series
of beautiful engravings. See Observations on the
different Species of Asiatic Elephants, and their Mode
of Dentition.
Phil. Trans. 1799, part 2.

We never see more than one grinder, and part
of another, through the gum in this animal. The
anterior one is gradually worn away by mastication;
its fangs and alveolus are then absorbed: the pos-
[Seite 83] terior tooth coming forwards to supply its place.
As this goes through the same stages as the pre-
ceding grinder; a third tooth, which was contained
in the back of the jaw, appears through the gum,
and advances, in proportion as the destruction and
absorption of the other proceed. The same pro-
cess is repeated at least eight times; and each new
grinder is larger than that which came before it.
The 1st, or milk grinder, is composed of four trans-
verse plates or denticuli, and cuts the gum soon
after birth. The 2d, which has eight or nine
plates, has completely appeared at the age of two
years. The 3d, formed of twelve or thirteen, at
six years. From the 4th to the 8th grinder, the
number of plates varies from fifteen to twenty-
three, which is the largest hitherto ascertained.
The exact age at which each of these is completed,
has not yet been made out. But it appears, that
every new one takes at least a year more for its
formation than its predecessor.

From the gradual manner, in which the tooth
advances, it is manifest, that a small portion of it
only can penetrate the gum at once. A grinder,
consisting of twelve or fourteen plates, has two or
three of these through the gum, whilst the others
are imbedded in the jaw. The formation of the
tooth is complete therefore, first, at its anterior part,
which is employed in mastication, while the back
part is very incomplete; as the succeeding laminae
advance through the gum, their formation is suc-
[Seite 84] cessively perfected. But the posterior layers of the
tooth are not employed in mastication, until the
anterior ones have been worn down to the very
fang, which begins to be absorbed. One of these
grinders can never therefore be procured in a perfect
state: for if its anterior part has not been at all
worn, the back is not completely formed, and the
fangs in particular are wanting; while the structure
of the back of the tooth is not completed, until the
anterior portion has disappeared.

A similar kind of succession, but to a less extent,
bas been ascertained by Mr. Home, in the teeth of
the sus Aethiopicus.

Observations on the Structure of the Teeth of Gra-
minivorous Quadrupeds; particularly those of the
Elephant, and sus Aethiopicus.
Phil. Trans. 1799,
part 2.

The researches of the same gentleman have also
proved it to exist in the wild boar to a certain
degree; and have rendered it probable, that it
occurred likewise in the animal incognitum (mam-
moth
).

Observations on the Structure and Mode of Growth
of the Wild Boar, and Animal Incognitum.
Phil.
Trans. 1801, part 2.

(V) The numbers of cervical vertebrae is the
same in the cetacea, as in other mammalia, according
to Cuvier; but some of them are anchylosed.
Thus the two first are united in the dolphin and
[Seite 85] porpoise; and the six last in the genus physeter.
Léçons d’Anat. Comp.
tome 1, p. 154.

It must be accounted a singular circumstance,
that the number of cervical vertebrae should be so
constantly the same in animals, whose neck differs
so much in length; when the number of pieces in
the other regions of the spine, varies greatly in the
different genera. No instance has, I believe, been
recorded, in which more than seven cervical ver-
tebrae have been found in the human subject;
although the number of those in the back and loins
sometimes deviates from the natural standard.

(W) These processes, which are particularly con-
spicuous in such carnivorous animals, as have great
strength in their neck, afford attachment to the large
and powerful muscles, by which the animal exe-
cutes those strong and rapid motions of the head,
which are necessary in attacking its prey, or de-
fending itself. The badger, in this country, affords
an excellent specimen of the structure alluded to.

The mole and shrew have no spinous processes
in the neck. The vertebrae form simple rings, with
considerable motion on each other. These pro-
cesses are either very short, or altogether deficient
in the long necked animals; as the horse, camel,
giraffe,
&c. They would otherwise afford an ob-
stacle to the bending of the neck backwards.

The six last vertebrae of the neck are anchylosed
in the ant-eater and manis.

[Seite 86]

(X) Most of the simiae, and even some, which
very much resemble the human subject, as the
orang-outang, which Camper dissected, (simia pyg-
maeus
), have the sacrum formed of three pieces;
which consequently leave only two pair of open-
ings for the passage of the nerves. Now, as
Galen mentions these circumstances of the human
sacrum, in his work on the bones, it must appear
very clearly that the description could not have been
taken from the human subject; but was probably
derived, as Vesalius supposed, from the ape; al-
though Silvius and Eustachius have endeavour-
ed to invalidate this conclusion. See Vesal. Epist.
de rad. Chynae;
also his great work, De Corp. hum.
Fabricâ,
p. 99.

The true orang-outang (simia satyrus) has a
sacrum composed of five pieces. The elephant has
also five. See Blair Osteogr. Elephantina, p. 29.

(Y) In monkeys, and even in such simiae as have
no tails, where the os coccygis consists at most of
three pieces only; this bone is perforated by a con-
tinuation of the vertebral canal, and by openings
for the transmission of nerves. This structure is
ascribed by Galen to the human coccyx; and
hence Vesalius has derived another argument, to
shew that Galen’s Osteology was not drawn from
the human skeleton.

The orang-outang, like man, has a coccyx com-
posed of five pieces, not perforated. Tyson’s
Anat. of a Pigmy, p. 69.

[Seite 87]

Those vertebrae of the tail of mammalia, which
are nearest to the sacrum, are perforated by a con-
tinuation of the canal for the medulla spinalis.
The lower ones are solid. The want of pelvis ren-
ders it impossible for us to decide the number of
sacral and coccygeal vertebrae in the cetacea: but
the whole number of pieces in the spine of the dol-
phin
and porpoise is 66.

(Z) Ossification of the cartilage, which connects
the two ossa pubis, is so rare in the human subject,
that one case only of complete anchylosis of these
bones has been hitherto recorded: (Soemmerring
de Corp. human. Fab. tom. 1. p. 22. note ***) al-
though several instances of partial bony union have
been observed. See Sandifort, Obs. Anat. Pa-
thol,
vol. 2.; Wynpresse de Ancylosi; and Mi-
chell
de Synchondrotomia pubis. Amstelod. 1783.
Such an occurrence is not, however, very rare in the
horse.

(A a) The onithorhynchus paradoxus and histrix
have ribs of a very singular structure. Their true
ribs, which are six in number, consist of two pieces
of bone; a longer one joined to the spine, and a
shorter connected to the sternum. These are united
by means of a piece of cartilage; so as to constitute
a structure, approaching to that of birds. The false
ribs, ten in number, terminate anteriorly in broad,
flattened, oval bony plates, connected together by
elastic ligaments. Phil. Trans. 1802, part 1, plate 3.

[Seite 88]

(B b) This process may be compared to the keel-
like projection of the sternum of birds. It serves
for the origin of those strong muscles of the anterior
extremity, which assist the animal in digging its way
under ground.

(C c) We may assert, as a general observation,
that the four component parts of the upper extre-
mity, viz. the shoulder, arm, fore-arm, and hand,
can be clearly shewn to exist in the anterior extre-
mities of all mammalia; however dissimilar they
may appear to each other on a superficial inspec-
tion, and however widely they may seem to deviate
from the human structure.

Whenever an animal of one class resembles those
of a different order in the form and use of any part,
we may be assured, that this resemblance is only in
externals; and that it does not affect the number
and arrangement of the bones. Thus the bat has
a kind of wings; but an attentive examination will
prove, that these are really hands, with the pha-
langes of the fingers elongated. The dolphin, por-
poise,
and other cetacea, seem to possess fins, consist-
ing of a single piece. But we find under the inte-
guments of the fin-like members, all the bones of
an anterior extremity, flattened in their form, and
hardly susceptible of any motion on each other.
We can recognize very clearly the scapula, hu-
merus, bones of the fore-arm, and a hand consist-
ing of five fingers: the same parts, in short, which
[Seite 89] form the anterior extremity of other mammalia.
See Tyson’s Anatomy of a Porpoise, fig. 10 and
11.: also Blasii Anatomia Animalium, tab. 51,
fig. 3, 4.

The fore-feet of the sea-otter, seal, walrus, and
manati, form the connecting link between the an-
terior extremities of other mammalia, and the pec-
toral fins of the whale kind. The bones are so
covered and connected by integuments, as to con-
stitute a part, adapted for the purposes of swimming:
but they are much more developed than in the lat-
ter animals, and have free motion on each other.

The cold-blooded quadrupeds bear great analogy
in the four component parts, and in the general
structure of their anterior extremities, to the warm-
blooded ones. See Caldesi’s Observations on the
Turtle,
tab. 3. fig. 1. 4, 5.

The bones of the wing of birds have a consider-
able and unexpected resemblance to those of the
fore-feet of the mammalia. And the fin-like ante-
rior member of the penguin contains, within the
integuments, the same bones as the wings of other
birds.

(D d) The clavicle supports the anterior extremity,
and maintains the shoulder at its proper distance from
the front of the trunk. It exists, therefore, in all
such animals as make much use of these members,
whether for the purpose of climbing, digging, swim-
ming, or flying. It does not exist, on the contrary,
[Seite 90] in such as use their fore-feet merely for the purpose
of progression; since these limbs must be brought
more forwards on the chest, that they may support
that part, by being placed perpendicularly under it.
In the genera, which hold an intermediate rank be-
tween these; which do not enjoy such an extensive
utility of the fore-feet as the first division of ani-
mals; and are not so limited in their employment
as the second, the clavicular bones, or imperfect
clavicles exist.

(E e) The humerus becomes shorter, in propor-
tion as the metacarpus is elongated; so that in ani-
mals, which have what is called a cannon bone, the
os humeri hardly extends beyond the trunk. Hence
the mistakes, which are made in common language,
by calling the carpus of the horse his fore-knee, &c.

The radius forms the chief bone of the fore-arm
in the mammalia, generally speaking; the ulna is a
small slender bone, terminating short of the wrist
in a point, and often consolidated with the radius,
as in the horse and ruminating animals. A few ge-
nera, which have great and free use of their anterior
extremity, have the power of pronation and supi-
nation. But this power diminishes, as the fore-feet
are used more for the purpose of supporting the
body in standing, and in progression. In this case,
indeed, the extremity may be said to be constantly
in the prone position, as the back of the carpus and
toes is turned forwards.

[Seite 91]

The lower end of the ulna is larger than that of
the radius in the elephant; but this circumstance
occurs in no other instance.

The radius and ulna exist in the seal, manati, and
whales, but in a flattened form.

Several genera of mammalia possess a hand; but
it is much less complete, and consequently less
useful than that of the human subject, which well
deserves the name bestowed on it by Aristotle, of
the organ of all organs. The great superiority of
that most perfect instrument, the human hand,
arises from the size and strength of the thumb,
which can be brought into a state of opposition to
the fingers, and is hence of the greatest use in
grasping spherical bodies, in taking up any object
in the hand, in giving us a firm hold on whatever
we seize; in short, in a thousand offices, which
occur every moment of our lives, and which either
could not be accomplished at all, if the thumb
were absent, or would require the concurrence of
both hands, instead of being done by one only.
Hence it has been justly described by Albinus as
a second hand ‘“manus parva majori adjutrix,”’
de sceleto, p. 465.

All the simiae possess hands: but even in those,
which may be most justly stiled anthropomorphous,
the thumb is small, short, and weak; and the other
fingers elongated and slender. In others, as some
of the cercopitheci, there is no thumb, or at least it
is concealed under the integuments; but these
[Seite 92] animals have a kind of fore paw, which is of some
use in seizing and carrying their food to the mouth,
in climbing, &c. like that of the squirrel. The
genus lemer has also a separate thumb. Other
animals, which have fingers sufficiently long and
moveable for seizing and grasping objects, are
obliged, by the want of a separate thumb, to hold
them by means of the two fore-paws; as the squirrel,
rat, opossum, &c. Those, which are moreover
obliged to rest their body on the fore-feet, as the
dog and cat, can only hold objects by fixing them
between the paw and the ground. Lastly, such
as have the fingers united by the integuments, or
enclosed in hoofs, lose all power of prehension.

The simiae in general have nine bones in the
carpus. Riolani Anthropographia and Osteolog.
p. 908. Paris, 1626; but there are only eight
in the orang-outang, according to Tyson. There
are five carpal bones in the fin of the whale, of a
flattened form, and hexagonal.

The metacarpus is elongated in those animals,
where the toe only touches the ground in standing
or walking; and constitutes the part, which is
commonly called the fore-leg; as the carpus is
termed the knee.

The number of metacarpal bones is the same
with that of the fingers or fore-toes: except in
the ruminating animals. Even in these, as the
author observes, there are two distinct metacarpal
bones, lying close together before birth: the
[Seite 93] opposed surfaces first become thinner, then are
perforated by several openings, and at last disap-
pear; so that the adult animal has a single cannon
bone, possessing a common medullary cavity inter-
nally, and marked on the outside with a slight
groove at the place of the original separation.
There is therefore but one metacarpal bone in the
adult for the two toes. The structure of the meta-
tarsus is the same.

In the horse on the contrary, if we allow the
splint bones to belong to the metacarpus, there will
be three to a single toe. Daubenton considers
the common bone of this animal as supplying the
place of the three metacarpal bones of man: he
compares the outer splint bone to the metacarpal
of the little finger, and the inner to that of the
thumb. Stubbs views the cannon as the meta-
carpal of the middle and ring fingers; and the
inner splint, as that of the fore-finger. Buffon
Hist. Naturelle, 4to. ed. p. 362. vol. 4. Stubbs’s
Anatomy of the Horse.

The single finger or fore-toe of the horse is com-
posed of the usual three phalanges; the first, which
is articulated to the cannon, is called the pastern;
the 2d is the coronet; and the 3d the os basis or
coffin bone; on which the hoof rests. There are
also two sesamoid bones at the back of the pastern,
joint: and an additional part called the shuttle-bone
connected to the coffin.

[Seite 94]

In those animals, which have five toes, as the
carnivora, &c., that which lies on the radial side
of the extremity, and is therefore analogous to the
thumb, is parallel with the others; and the animal
consequently has not the power of grasping any
object. The last phalanx in these supports the nail
of the animal; and sends a process into its cavity.
These parts are so connected that the nail is na-
turally turned upwards, and not towards the
ground; so that its point is not injured in the mo-
tions of the animal. The phalanx must be bent in
order to point the nail forwards or downwards.

The order of rodentia have generally five toes:
that which corresponds to the thumb being the
shortest.

The elephant has five complete toes; but they
are almost concealed by the thick skin.

The pig has four toes; two larger ones, which
touch the ground; and two smaller behind these,
which do not reach so far. There is also a bone,
which seems to be the rudiment of a thumb.

The phalanges of the cetacea are flattened; not
moveable, and joined together in the fin.

(F f) The length of the femur depends on that
of the metatarsus; and it bears an inverse ratio to
the length of that part.

Hence it is very short in the horse, cow, &c.
where the same mistakes are commonly com-
[Seite 95] mitted in naming the parts, as in the anterior
extremity.

The proportions of the thigh and leg vary in
different animals. The latter part exceeds the
former in the human subject; and the same remark
may be made respecting the arm and fore-arm.
These parts are nearly of the same length in the
orang-outang. Some persons have affirmed that the
Negro forms a connecting link between the Eu-
ropean and the orang-outang in these respects.
(White on the regular Gradation in Man and Ani-
mals,
&c). In some other simiae the leg and fore-
arm exceed the thigh and arm. In other animals,
although they are some varieties, the leg is gene-
rally longer than the thigh.

The femur of the mammalia is not arched as in
the human subject: it possesses scarcely any neck;
and the great trochanter ascends beyond the head
of the bone.

The fibula is behind the tibia in many animals,
as the dog and the rodentia. It is consolidated to that
bone at its lower end in the mole and rat. It only
exists as a small styloid bone in the horse, and be-
comes anchylosed to the tibia in an old animal.

The structure of the metatarsus in the rumi-
nating animals, and the horse, is the same with that
the metacarpus.

The tarsus of the horse is composed of six bones;
and is the part known in common language by the
name of the hock.

[Seite 96]

Animals of the genus simia and lemur, instead of
having a great toe placed parallel with the others,
are furnished with a real thumb: i.e. a part capable
of being opposed to the other toes. Hence these
animals can neither be called biped, nor quadruped,
but are really quadrumanous or fourhanded. They
are not destined to go either on two or four extre-
mities, but to live in trees, since their four prehen-
sile members enable them to climb with the greatest
facility. So that Cuvier has denominated them
‘“les grimpeurs par excellence.”’ (Leçons d’Anat.
Comp. vol. 1. p. 493.) The prehensile tail of
several species is a further assistance in this way of
life. The opossum, and others of the genus didelphis,
have a similar structure with the quadrumana; and
it answers the same purpose. Here however there
is a separate thumb on the posterior extremity only,
whence Cuvier calls them pedimanes.

Man is the only animal, in which the whole
surface of the foot rests on the ground: and this
circumstance arises from the erect stature, which
belongs exclusively to him. In the quadrumana;
in the bear, hedgehog, and shrew, (which are called
by Cuvier plantigrades), the os calcis does not
touch the ground.

The heel of a species of bear belonging to this
country, viz. the badger (ursus meles), is covered
with a long fur, which proves that this part cannot
rest on the ground; although the structure both of
the bones and muscles of the lower extremity of
[Seite 97] this animal, approaches considerably to that of
man. The same fact is stated of the bear itself,
properly so called, by the Parisian dissectors, Descrip-
tion anatomique d’un cameleon, d’un castor, d’un ours,

&c. Paris, 1669, 4to. the plate is contained in
Blasius’s Collection, tab. 32.

In other animals the body is supported upon the
phalanges of the toes, as in the dog and cat; in the
horse and ruminating animals no part touches the
ground but the last phalanx. Here the elongation
of the metatarsus removes the os calcis to such a
distance from the toe, that it is placed midway be-
tween the trunk and hoof.

CHAPTER III.
ON THE SKELETON OF BIRDS.

[Seite 98]

§ 46. The skeleton of birds has considerable
uniformity in the whole class; and it exhibits,
when compared with the variously formed skeletons
of mammalia, a very great and unexpected simila-
rity to that of the human subject1.

§ 47. The skull of birds is distinguished by
this peculiarity, that the proper bones of the cra-
nium2, at least in the adult animal, are not joined
by sutures, but are consolidated as it were into a
single piece3.

[Seite 99]

They have, without exception, only a single
condyle, placed at the anterior margin of the great
occipital foramen. (See note (A) at the end of the
chapter).

There is also, in the whole class, a bone of a
somewhat square figure, (called by the French os
carré
4), by which the lower jaw is articulated
with the cranium on both sides, in the neighbour-
hood of the ear. (See note (B) at the end of the
chapter).

The ossa unguis are common to birds with mam-
malia, but appear to be more general in the former
than the latter: they are of considerable size,
and must be distinguished from the superciliary5
bones which probably belong to the accipitres (or
predacious birds) only.

§ 48. The jaws are completely destitute of
teeth. (See note (C) at the end of the chapter).
The superior maxilla, which is completely im-
[Seite 100] moveable in mammalia, has, with a few exceptions,
more or less motion in birds6. It either constitutes
a particular bone, distinct from the rest of the
cranium, to which it is articulated, as is the
Psittaci7 (birds of the parrot kind); or it is con-
nected into one piece with the cranium, by means
of yielding and elastic bony plates; as is the case
with birds in general. It is quite immoveable in a
very few instances; as the tetrao urogallus (cock
of the woods) and the rhinoceros bird8.

§ 49. The proportionate magnitude of the
bones of the cranium and jaws varies much in
this class. The former are large in the owl; the
latter are of vast magnitude in the rhinoceros
bird9.

[Seite 101]

§ 50. One of the peculiar characteristic dif-
ferences of the cranium of birds when compared
to each other10, consists in the mode of separa-
tion of the orbits, which are of great size in the
whole class. In some they are separated by a
membranous partition only; in others by a more
or less complete bony septum. The relation, which
the nasal and palatine openings bear to the upper
jaw varies much, even in the different species of
the same genus. They are small in the stork; and
on the contrary so large in the crane that the longest
portion of the jaw appears to consist merely of
three thin portions of bone, placed far apart from
each other, and converging towards the point of
the bill.

§ 51. The want of motion in the back of
birds, (their dorsal vertebra have the spinous, and
even the transverse processes, often anchylosed)
is compensated by a larger number, and greater
mobility of the cervical vertebrae; of which, to
[Seite 102] quote a few instances, the raven has 12, the cock
13, the ostrich 18, the stork 19, and the swan 23.

§ 52. The trunk of birds has fewer cartilagi-
nous parts than the corresponding division of the
skeleton in mammalia. That part of the spine,
which belongs to the trunk is short and rigid, and
has no true lumbar vertebrae. Neither has any
bird an os coccygis prolonged into a true jointed
tail*.

§ 53. The pelvis of birds is chiefly formed by
a broad and simple os innominatum; the lateral
portions of which are of different figures in the
several genera; but, instead of uniting below to
constitute a symphysis pubis, they are quite distant
from each other. The ostrich alone forms a re-
markable exception to this rule; in as much as its
pelvis, like that of most quadrupeds, is closed be-
low by a complete junction of the ossa pubis.

§ 54. Birds have fewer ribs than mammalia:
the number, I believe, never exceeds ten pairs. The
false ribs, i.e. those, which do not reach to the
sternum, are directed forward; the true ones are
joined to the margin of the sternum by means of
small intermediate bones. The middle pairs are
[Seite 103] distinguished by a peculiar flat process, which is
directed upwards and backwards.

§ 55. The sternum of these animals is pro-
longed below into a vertical process, (crista) for
the attachment of the strong pectoral muscles.
In the male wild swan (anas cygnus), and in some
species of the genus ardea, as the crane, this
part forms a peculiar cavity for the reception of
a considerable portion of the trachea. The crista
is entirely wanting in the ostrich and cassowary;
where the sternum presents a plane and uniformly
arched surface*.

§ 56. The wings are connected to the trunk
by means of three remarkable bones11. The clavicles,
which are always strong, constitute straight cylindri-
cal bones. Their anterior extremities are connected
to the sternum, by means of a bone peculiar to
birds; viz. the forklike bone, or, as it is more com-
monly termed, the merry thought. (Furcula, in
[Seite 104] French la lunette, or fourchette)*. (See note (E)
at the end of the chapter.)

§ 57. The bones of the wing may be com-
pared on the whole to those of the upper extre-
mity in man, or the quadrumana; and consist
generally of an os humeri; two bones of the fore-
arm; two of the carpus; two, which are generally
consolidated together, of the metacarpus; one
bone of the thumb; and two fingers; of which
that which lies towards the thumb consists of two
portions, the other only of one. The most re-
markable deviation from this structure, in respect
to the number, as well as the formation and rela-
tive proportion of the bones, is found in the fin-like
wings of the penguins. All the bones are here of
a very remarkable flattened form, as if they had
been pressed; there are two supernumerary bones
at the elbow; and the bone of the thumb is entire-
ly wanting.

§ 58. The bony structure of the lower extre-
mities is more simple in birds, than in mammalia.
In general it comprehends only the following
[Seite 105] bones, viz. the femur, the tibia, (to which, in some
instances, is added a small, thin, closely adhering
pointed fibula) one metatarsal bone, and the toes.
The place of the patella is supplied, in many cases,
by a process of the tibia. As birds have neither
a true fibula, nor tarsus, their tibia is immediately
articulated with the metatarsus. There is, in most
of this class, a peculiar progressive increase in the
number of phalanges of the toes: the great toe has
two; the next three; the middle one, four; and
the outer one, five12. The psittaci have, however, a
a peculiar cross-bone, belonging to the great toe*.


Additional Notes to the Third Chapter.

(A) This structure gives the head a great free,
dom of motion, particularly in the horizontal direc-
tion. It enables the bird to place its bill between
the wings, when asleep; a situation, in which none
of the mammalia can bring the snout.

[Seite 106]

(B) The os quadratum has a true articulation,
both with the lower mandible and with the cranium.
Another small bone is connected to it, and rests by
its opposite end against the palate. Hence, when
the square bone is brought forwards, which it is by
the depression of the lower mandible, and in a
greater degree by some particular muscles, the se-
cond bone presses against the palate, so as to elevate
the upper jaw.

(C.) The bill of birds may be considered, in
some degree, as supplying the place of teeth;
yet, as none of these animals masticate their food,
but swallow it whole, the bill can only be compared
to the incisors of such animals, as use them for seiz-
ing and procuring their food.

It consists of a horny fibrous matter, similar to
that of the nail, or of proper horns; and is moulded
to the shape of the bones, which constitute the two
mandibles, being formed by a soft vascular sub-
stance, covering these bones. Its form and struc-
ture are as intimately connected with the habits and
general character of the animal, as those of the teeth
are in the mammalia. Hence an enumeration of
its different figures and consistence, belongs pro-
perly to the department of natural history, where
it forms the foundation of classific distinctions.

The accipitres, or rapacious birds, have it very
hard, hooked at the end, and furnished with a pro-
cess on either side; calculated, therefore, in all re-
[Seite 107] spects, for seizing and lacerating their prey. Those
of the parrot kind have it also hard, for bruising the
firmer vegetable fruits; and the wood-pecker, nu-
thatch,
&c. for penetrating the bark of trees.

Those birds, which take a softer kind of food,
and which require a sense of feeling in the part, for
distinguishing their food in mud, water, &c. have it
approaching to the softness of skin. Such are the
duck, snipe, woodcock, &c.

In several classes, particularly the accipitres and
gallinae, the base of the bill is covered with a soft
skin, called the cire, of unknown use.

(D) The number of cervical vertebrae in birds,
varies from ten to twenty-three; those of the back
from seven to eleven. From hence to the tail, they
are consolidated into one piece with the os innomi-
natum. The tail has from seven to nine pieces.

The length of the neck increases in general, in
proportion to that of the legs.

The cervical vertebrae are not articulated by plane
surfaces, but by cylindrical eminences, which admit
a more extensive motion, as they constitute real
joints, instead of synchondroses. Four or five of
the upper pieces only bend forwards; while the
lower ones are confined to flexion backwards.
Hence the neck of a bird acquires that double
bend, which makes it resemble the letter S. It is
by rendering the two curvatures more convex, or
[Seite 108] more straight, that the neck is shortened or elon-
gated. The great mobility of the neck, enables
birds to touch every point of their own body with
the bill, and thus to supply the want of the prehen-
sile faculty of the superior extremity.

(E) The point of the fork-like bone is joined to
the most prominent part of the keel of the sternum;
and the extremities of its two branches are tied to
the humeral end of the clavicles, and the front of
the scapulae, just where these bones join each other,
and are articulated with the humerus. Hence it
serves to keep the wings apart in the rapid motions
of flying. ‘“As a general observation, it may be
stated, that the fork is strong and elastic; and its
branches wide, arched, and carried forwards upon
the body, in proportion as the bird possesses strength
and rapidity of flight; and accordingly the stru-
thious birds (ostrich
and cassowary), which are in-
capable of this mode of progression, have the fork
very imperfectly formed. The two branches are
very short, and never united in the African ostrich,
but are anchylosed with the scapula and clavicle.
The cassowary has merely two little processes from
the side of the clavicle, which are the rudiments of
the branches of the fork. In the New Holland
ostrich
there are two very small thin bones, which
are attached to the anterior edge of the dorsal end
of the clavicles by ligament; they are directed up-
[Seite 109] wards towards the neck, where they are fastened to
each other by means of a ligament, and haver no
connection whatever with the sternum.”’

Macartney, in Rees’s Cyclopaedia. Article
Birds, Anatomy of.

(F) Birds certainly have a fibula, contrary to the
assertion of the author; but it is small, and soon
anchylosed to the tibia.

The lower end of the bone, which answers to
the tarsus and metatarsus, forms as many processes
as there are toes; and each of these has a pulley,
for articulation, with its corresponding toe.

The vast length of the leg in the wading birds
(grallae), the ostrich, and cassowary, is produced by
the tibia, and common bone of the tarsus and meta-
tarsus; for the femur is comparatively short.

‘“The stork, and some others of the grallae,
which sleep standing on one foot, possess a curious
mechanism, for preserving the leg in a state of ex-
tension, without any, or at least with little muscular
effort. There arises from the fore-part of the head
of the metatarsal bone, a round eminence, which
passes up between the projections of the pulley, on
the anterior part of the end of the tibia. This
eminence affords a sufficient degree of resistance to
the flexion of the leg, to counteract the effect of
the oscillations of the body, and would prove an
insurmountable obstruction to the motion of the
[Seite 110] joint, if there were not a socket within the upper
part of the pulley of the tibia, to receive it when the
leg is in the bent position. The lower edge of the
socket is prominent and sharp, and presents a sort
of barrier to the admission of the eminence, that re-
quires a voluntary muscular exertion of the bird to
overcome, which being accomplished, it slips in with
some force, like the end of a dislocated bone.”’

Macartney, loco citato.

CHAPTER IV.
ON THE SKELETON OF AMPHIBIA.

[Seite 111]

§ 59. The general form of the body, and conse-
quently the structure of the skeleton varies so much,
in the first place, in the two orders of this class, viz.
the four-footed amphibia, and the serpents; and se-
condly, in the three leading classes of the first order,
namely, the testudines, the frogs, and the lizards;
that it will be best to arrange our observations on
this subject, according to the natural divisions of the
orders and classes.

§ 60. The testudines (turtles and tortoises),
whose whole skeleton1, and indeed whose whole
body has a very peculiar structure, are entirely
toothless; they have, however, a kind of os inter-
maxillare in the upper jaw. The horny covering
of the jaws, particularly the upper one, has some
[Seite 112] resemblance to the horse’s hoof, in the mode of its
connection with the jaw. The cavity, containing
the brain, is extremely small, in comparison with the
size of the skull; the greatest part of which, in the
turtle, is occupied by the large lateral hollows,
holding the eye, and the powerful muscles that
move the lower jaw. (See note (A) at the end of
the chapter.)

§ 61. The trunk is consolidated with the two
great shells of the animal; the dorsal vertebrae and
ribs being attached to the upper, the sternum being
fixed in the lower or abdominal shell. The upper
bony covering, or that of the back, consists of about
fifty pieces; which are partly connected together
by real sutures.

§ 62. The same bones are found in the pelvis
of these animals, as in the mammalia; but the pro-
portion of their relative size is inverted. For in-
stance, the ossa pubis are so deep and broad, that
they form the largest flat bones in the whole skele-
ton, while the ilia are the smallest.

§ 63. The form and position of the scapula
and clavicle are the most extraordinary. The for-
mer has a most anomalous situation towards the
under part of the animal, just behind the abdominal
shell; the latter consists of two pieces, joined at an
acute angle, to which the humerus is articulated.

[Seite 113]

§ 64. Frogs and toads2 have no teeth3. Their
spine is short, terminates behind in a straight and
single bone, which is received into the middle of
the somewhat fork-like os innominatum.

§ 65. They have no ribs; but the dorsal ver-
tebrae are furnished with broad tranverse processes.
The scapula, which is thin and flat, and a pair of
bones, corresponding to the clavicle, are joined to
the sternum.

§ 66. The bone of the fore-arm and of the leg
have a peculiarity of structure, in these animals,
which deserves observation. These bones consist
of a single piece, which is solid in the middle, but
divided at either extremity, into two conical por-
tions, having manifest medullary cavities4.

[Seite 114]

§ 67. The crocodile5 may be taken as an ex-
ample of the class of lizards6, on account of some
remarkable peculiarities of structure. In no other
animal are the jaws of such immense size, in com-
parison with the extremely small cavity of the cra-
nium. The anterior part of the upper jaw, consists
of a large intermaxillary bone; and the lateral por-
tions of the lower maxilla, are formed of several
pieces joined together. The lower jaw7 is arti-
culated, in a peculiar manner, in these animals: it
has an articular cavity, in which a condyle8 of the
upper jaw is received.

§ 68. Their numerous teeth have this pecu-
liarity of structure; that, in order to facilitate their
[Seite 115] change, there are always two, of which one is con-
tained within the other9.

§ 69. But the most surprising singularity in the
skeleton of the crocodile, consists in an abdominal
sternum, which is quite different from the thoracic
sternum, and extends from the ensiform cartilage
the pubis, apparently for the purpose of support-
ing the abdominal viscera10.

[Seite 116]

§ 70. The serpents11 have an upper jaw, un-
connected with the rest of the skull, and more or
less moveable of itself.

§ 71. We find in their teeth, the important
and clearly defined difference, which distinguishes
the poisonous species of serpents, from the much
more numerous innoxious tribes.

The latter have, in the upper jaw, four maxillary
bones, beset with small teeth, which form two rows,
separated by a considerable interval from each
other. One of these is placed along the front edge
of the jaw; the other is found more internally, and
is situated longitudinally on either side of the
palate.

The external row is wanting in the poisonous
species; which have, in their stead, much larger
tubular fangs, connected with the poison bladder,
and constituting, in reality, bony excretory ducts,
which convey the venom into the wound, inflicted
by the bite of the animal12.

[Seite 117]

§ 72. It appears, in general, that the number
vertebrae in red-blooded animals, is in an inverse
proportion with the size and strength of their exter-
nal organs of motion. Serpents, therefore, which
entirely want these organs, have the most numerous
vertebrae; sometimes more than 300. (See note
(B) at the end of the chapter).

The last vertebrae of the tail, in the rattlesnake,
are broad, and covered by the first hollow pieces
of the horny rattle: the succeeding portions of this
singular and mysterious organ13, are connected to
each other in a most curious way.

§ 73. Serpents possess by far the greatest num-
ber of ribs; which amount, in some, to 250 pairs.
It is necessary to mention here the costae scapulares
of the cobra di cabelo (coluber naiae), which enable
the animal to inflate its neck14.

[Seite 118]

Serpents are the only red-blooded animals, which
have no sternum*.


Additional Notes to the Fourth Chapter.

(A) This circumstance is still more remarkable
in the crocodile. The cranium of an individual,
measuring thirteen or fourteen feet, will hardly
admit the thumb: and the area of its section does
not constitute the twentieth part of that of the
whole head.

The chameleon affords another instance of the
same structure: its brain, according to the de-
scription of the Parisian dissectors, does not seem
larger than a pea; and the whole of the head,
which is of considerable size, consists of the large
maxillary bones, the orbits, and immense temporal
fossae, which, not being separated by any partition,
give the cranium a very singular appearance.

See the Description anatomique d’un Cameleon, &c.
or Blasius’s Collection, tab. 14.

(B) In may be observed in confirmation of this
remark, that the number of vertebrae is very great
[Seite 119] in fishes of an elongated form; viz. in the eel,
which has above one hundred. The porpoise,
which has no organs of motion, which deserve
mentioning, has between sixty and seventy.

Birds, which have such vast power of locomotion
by means of their wings, have very few vertebrae,
if we consider the anchylosed ones as forming a
single piece. And the frog, with its immense hind
extremities, has a very short spine, consisting of
still fewer pieces.

(C) The occiput is connected to the atlas by a
single condyle in the crocodile and turtle: in the
lizard and tortoise there is a flight appearance of di-
vision into two surfaces: in the frog and toad there
are two condyles; and in the serpents there are
three articular surfaces on a single tubercle.

The condyle of the turtle being deeply imbedded
in the atlas, the motions of the articulation must
be limited: the protraction and retraction of the
head in this animal is effected by the flexion and
extension of the vertebrae of the neck.

The lower jaw is articulated with an eminence of
the cranium in the lizards, turtles, frogs, salaman-
ders, blindworms, (anguis fragilis
) and amphisbaena;
besides the crocodile in which the author mentions
it. This bony eminence, is compared by Cuvier
to the os quadratum of birds. The lower jaw only
is moveable in these animals. Its articulation in
[Seite 120] the turtle is by means of a ginglymus. In all the
venomous serpents the upper jaw is moveable on
the head, as in birds: these animals require as ex-
tensive an opening of the mouth as possible, since
they swallow others whole, actually larger than
their own body.

CHAPTER V.
ON THE SKELETON OF FISHES.

[Seite 121]

§ 74. We should naturally conclude, from ob-
serving the great diversity in the general form of
fishes, that the structure of their skeleton must be
equally various1. They agree together, however,
on the whole, in having a spine, which extends
from the cranium to the tail-fin; and in having
the other fins, particularly those of the thorax and
abdomen, articulated with peculiar bones, destined
to that purpose. They have in general many
more bones unconnected with the rest of the
skeleton, than the animals of the preceding
classes*.

[Seite 122]

§ 75. The cranium in several cartilaginous
fishes, (in the skate for instance) has a very simple
structure, consisting chiefly of one large piece.
In the bony fishes, on the contrary, its component
parts are very numerous; amounting to 80 in the
head of the perch. Most of the latter have a more
or less moveable under-jaw.

§ 76. Great variety in the structure of the
teeth is observed in this class. Some genera, as
the sturgeon, are toothless. Their jaws, which
are distinct from the cranium, form a moveable
part, capable of being thrust forwards from the
mouth, and again retracted.

§ 77. Those fishes, which possess teeth, differ
very much in the form, number, and position of
these organs. Some species of sparus, (as the
S. probato-cephalus) have front-teeth almost like
those of man3; they are provided with fangs, which
[Seite 123] are contained in alveoli. In many genera of fishes,
the teeth are formed by processes of the jaw-bones
covered with a crust of enamel. In most of the
sharks, the mouth is furnished with very numerous
teeth for the supply of such as may be lost. The
white shark has more than two hundred, lying on
each other in rows, almost like the leaves of an
artichoke. Those only, which form the front row,
have a perpendicular direction, and are completely
uncovered. Those of the subsequent rows are,
on the contrary, smaller; have their points turned
backwards, and are covered with a kind of gum.
These come through the covering substance, and
pass forward when any teeth of the front row are
lost4. It will be understood from this description,
that the teeth in question cannot have any fangs.

The saw-fish only (squalus pristis) has teeth im-
planted in the bone on both sides of the sword-
shaped organ, with which its head is armed.

In some fishes the palate, in others the bone of
the tongue (as in the frog-fish), in others (as in
several of the ray-kind) the aperture of the mouth
forms a continuous surface of tooth5. (See note
(A) at the end of the chapter.)

[Seite 124]

§ 78. In the long shaped fishes with short fins,
the spine consists of a proportionally greater number
of vertebrae; of which the eel, for instance, has
more than 100, and some sharks even more than
200. The main-piece, or body, as it is called of
these vertebrae, is of a cylindrical figure, with a
funnel shaped depression on both surfaces, and con-
centric rings, which are said to vary in number,
according to the age of the animal. The spinal
marrow passes above these, in a canal formed at
the roots of the spinous processes.

The ribs are articulated with what are called
the dorsal vertebrae in most of the spinous fishes;
but in some they are without this connection; and
in the cartilaginous fishes proper ribs cannot be
said to exist.

§ 79. Of the peculiar bones, which serve as a
basis for the fins, that of the pectoral fin may be
compared to the scapula, and that of the abdominal
in some measure with the os innominatum6.

[Seite 125]

§ 80. Lastly, many fishes are furnished with
merely muscular bones (osicula muscullorum of
Artedi) which are sometimes bifurcated, are al-
ways situated among the muscles, and facilitate
their motion.


Additional Note to the Fifth Chapter.

(A) Great variety exists in the teeth of fishes;
and their structure, formation, and mode of growth
have been but imperfectly explained hitherto.

Many fishes have simple teeth, formed of a bony
substance,
covered by enamel, and probably formed
[Seite 126] as in the mammalia. These are the most common,
and may be seen in the pike. When the crown
has completely appeared, the root becomes anchy-
losed to the jaw.

In other cases they adhere to the gum only, or
at least to a firm cartilaginous substance, which
covers the jaw. This is exemplified in the shark.
These teeth seem not to be formed, as those of the
mammalia are, by the deposition of successive layers
one within the other; but in a manner more nearly
resembling the formation of bone. They are at
first soft and cartilaginous, and pass by successive
gradations, into a state of hardness and density,
not inferior to that of ivory.

A third kind of teeth consists of an assemblage
of tubes, covered externally by enamel, and con-
nected to the jaw by a softer substance, which pro-
bably sends processes or vessels into those bony
tubes. This is the case with the pavement, as we
may call it, of teeth, that covers the jaws of the
skate.

A similar structure is observed in the anarrhichas
lupus;
where the teeth, composed of bony tubes,
are connected to spongy eminences of the jaws,
which may be compared to epiphyses; and on their
separation leave a surface like that from which the
antler of the deer falls off.

Besides the two jaws, fishes have teeth implanted
in the bones of the palate; in that which corres-
[Seite 127] ponds to the vomer; in the os hyoides; in the
bones which support the franchiae; and in those
which are placed at the top of the pharynx. The
salmon and pike have them in all these situations.

CHAPTER VI.
ON THE OESOPHAGUS AND STOMACH.

[Seite 128]

§ 81. After the comparative view, which we
have now taken, of the skeleton, as influencing the
general form of the red-blooded animals, we pro-
ceed to consider the other parts of the animal
structure, and their functions. The ordinary divi-
sion into four classes of functions may be here re-
tained, as sufficiently applicable on the whole,
although it is in strictness subject to much limita-
tion. The particular classes of animals will be
considered in the subdivision of each chapter, ac-
cording to the arrangement most usually followed
in teaching zoology.

§ 82. The natural functions, as they are called,
which include, in their most extensive sense, the
whole process of nutrition, very properly take
the lead on this occasion. In the first place, they
exist in all classes of animals without exception;
they are indeed common to plants and animals:
secondly, the peculiar mode of their performance
in animals, constitutes the most distinguishing cha-
racter of an animal. For they seek their food by
[Seite 129] voluntary motion, and convey it into the stomach
through a mouth1.

[Seite 130]

§ 83. We have already shewn, in the second
chapter, the most important circumstances relating
to the mouth. Many species of the genus simia,
as well as the hamster, (marmota cricetus) and
some similar species of the marmot, are provided
with cheek pouches, in which the former, who live
on trees, place small quantities of food as a reserve:
the latter employ these bags to convey their winter
provision to their burrows2. (See note (A) at the
end of the chapter).

§ 84. The peculiar glandular and moveable
bag, (bursa faucium), which is placed behind the
palate, has hitherto been only observed in the
camels of the old world: and it probably serves
[Seite 131] to lubricate the throat of these animals in their
abode in the dry sandy desarts which they inhabit3.
(See note (B) at the end of the chapter.)

§ 85. The oesophagus of quadrupeds is dis-
tinguished from that of the human subject by
possessing two rows of muscular fibres, which pur-
sue a spiral course, and decussate each other. In
those carnivorous animals, which swallow vora-
ciously, as the wolf, it is very large; on the con-
trary, in many of the larger herbivora, and parti-
cularly in such as ruminate, its coats are propor-
tionally stronger4.

The opening of the oesophagus into the stomach
is marked by some differences, both with regard to
its size, and to the mode of termination. We
understand, from observing these points, why
some animals, as the dog, vomit very easily,
while others, as the horse, are scarcely suscepti-
[Seite 132] ble of this process5, except in extremely rare
instances6.

§ 86. The form, structure, and functions of
the stomach, are subject to great variety in this
class of animals. In most carnivorous quadrupeds7,
particularly those of a rapacious nature, it bears a
considerable resemblance, on the whole, to that of
the human subject: its form, however, differs in
some cases, as in the seal (phoca vitulina), where
the oesophagus enters directly at the left extremity,
so that there is no blind sac formed in the stomach.
In some animals, as in the lion, bear, &c. it is
divided by a slight contraction in its middle, into
[Seite 133] two portions. Its coats, particularly the muscular
one, are very strong in the carnivora8.

§ 87. In some herbivora the stomach has an
uniform appearance externally; but it is divided
into two portions internally, either by a remarkable
difference in the two halves of its internal coat9,
as in the horse10, or by a valvular elongation of
this membrane, as in several animals of the mouse-
kind. This is also the case in the hare and rabbit,
where also the food in the two halves of the
stomach, differs very much in appearance, parti-
cularly if the animal has been fed about two
hours before death. (See note (C) at the end of
the chapter).

[Seite 134]

§ 88. In some other mammalia, particularly
the herbivorous ones, this organ consists of two or
more portions manifestly distinct externally, and
forming as many stomachs. There are two of
these in the hamster11; three in the kanguroo12 and
tajaçu13; four in the sloths14.

The carnivorous cetacea have also a complicated
stomach, consisting in some species of three, in
others of four, and even of five subdivisions15.

§ 89. The most complicated and artificial ar-
rangement, both with respect to structure and
mechanism, is found in the well known four sto-
machs of the ruminating animals with divided
hoofs; of this we shall take as examples, the cow
and sheep16.

[Seite 135]

The first stomach, or paunch, (rumen, penula,
magnus venter, ingluvies
), is by far the largest in
the adult animal; not so however in the recently
born calf or lamb. It is divided externally into
two saccular appendices at its extremity, and it is
slightly separated into four parts on the inside.
Its internal coat is beset with innumerable flattened
papillae17.

[Seite 136]

This is followed by the second stomach, honey-
comb bag, bonnet,
or king’s-hood, (reticulum, ollula),
which may be regarded as a globular appendage
of the paunch; but is distinguished from the latter
part by the elegant arrangement of its internal
coat, which forms polygonal and acute-angled cells,
or superficial cavities.

The third stomach, which is the smallest, is
called the manyplus, which is a corruption of
manyplies (echinus, conclave, centipellio, omasum): it
is distinguished from the two former, both by its
form, which has been compared to that of a hedge-
hog when rolled up, and by its internal structure.
Its cavity is much contracted by numerous and
broad duplicatures of the internal coat, which lie
lengthwise, vary in breadth in a regular alternate
order, and amount to about 40 in the sheep, 100
in the cow.

The fourth, or the red, (abomasum, faliscus,
ventriculus intestinalis
), is next in size to the
[Seite 137] paunch, of an elongated pyriform shape, with an
internal villous coat like that of the human sto-
mach, with large longitudinal rugae.

§ 90. The three first stomachs are connected
with each other, and with a groove-like continua-
tion of the oesophagus, in a very remarkable way.
The latter tube enters just where the paunch, the
second and third stomachs approach each other; it is
then continued with the groove, which ends in the
third stomach. This groove is therefore open to
the first stomachs, which lie to its right and left.
But the thick prominent lips, which form the
margin of the groove, admit of being drawn to-
gether so as to form a complete canal: which then
constitutes a direct continuation of the oesophagus
into the third stomach.

§ 91. The functions of this very singular
part will vary, according as we consider it in
the state of a groove, or of a closed canal.
In the first case, the grass, &c. is passed after
a very slight degree of mastication, into the
paunch, as into a reservoir. Thence it goes in
small portions into the second stomach, from
which, after a further maceration, it is pro-
pelled, by a kind of antiperistaltic motion, into
the oesophagus, and thus returns into the mouth.
It is here ruminated, and again swallowed, when
[Seite 138] the groove18 is shut, and the morsel of food,
after this second mastication, is thereby conducted
directly into the third stomach19. During the
short time, which it probably stays in this situation
between the folds of the internal coat, it is still
further prepared for digestion, which process is
completed in the fourth or true digestive stomach20.
See note (E).

[Seite 139]

§ 92. There are still two peculiarities in the
stomachs of some mammalia, which must be men-
tioned here, before we proceed to consider that of
birds. (For the account of the camel’s stomach,
see note **, at the end of the chapter.)

In the opossum, the two openings of the stomach
are placed as near, or even nearer together than in
many birds; contrary to the usual rule, in this class
of animals.

There is a peculiar glandular body at the upper
orifice of the beaver’s stomach, about the size of a
florin, full of cavities, that secrete mucus. It resem-
bles, on the whole, the bulbus glandulosus of birds;
and assists in the digestion and animalization of the
dry food, which this curious animal takes, consist-
ing chiefly of the bark and chips of trees, &c.
See note (F).

The stomach of the pangolin (manis pentadactyla)
is almost as thick and muscular as that of the galli-
naceous fowls, and contains, like that of granivorous
[Seite 140] birds, small stones and gravel, which are probably
swallowed, for the same purpose, as in those birds1.
See note (G).

(B) Birds.

§ 93. As we have spoken above of the cheek-
pouches
of some mammalia, we must here take
notice of the throat sack, which is found in the male2
bustard, under the integuments of the front of the
neck; and opens by a wide aperture under the
tongue: its use has not been hitherto discovered3.
See note (N).

§ 94. The oesophagus, which generally de-
scends on the right of the trachea, as well as its
opening into the stomach, is of immense size in
[Seite 141] many carnivorous birds; considerably larger indeed
than the intestinal canal. The capaciousness of this
tube, enables it hold for a time4 the entire fish, and
large bones, which these birds swallow, and which
cannot be contained in the stomach; and to facili-
tate the discharge, by vomiting the indigestible re-
mains of the food, which form balls of hair, feathers,
and bony matter. See note (I).

§ 95. The oesophagus expands just before the
sternum into the crop (ingluvies, prolobus, le jabot),
which is furnished with numerous mucous, or sali-
vary glands, disposed in many cases in regular rows.
In such birds, as nourish their young from the crop,
the glands swell5 remarkably at that time, and se-
crete a greater quantity of fluid6. This part is
found in land birds only, but not in all of these;
it exists in all the gallinae, and in some birds of
of prey7. See note (K).

[Seite 142]

§ 96. There is another glandular and secretory
organ, much more common than the crop, belong-
ing indeed most probably* to the whole class.
This is the bulbus glandulosus (echinus, infundibulum,
proventriculus, corpus tubulosum
), which is situated
before the entrance of the oesophagus into the pro-
per stomach, and whose form and structure vary
considerably in the different genera and species. In
the ostrich, for example, its magnitude and form
give it the appearance of a second stomach8. In
some other birds, as the psittaci, ardeae (crane,
stork, &c.), its appearance is different from that of
the proper stomach, but its size is larger; while,
on the contrary, in gallinaceous fowls, it is much
smaller9. See note (L).

§ 97. In most birds, the stomach lies at the
upper10 part of the abdomen, that is, close to the
spine, and rests, in a manner, on a stratum of in-
testines; in the cuckoo, on the contrary, it lies be-
low. This peculiarity does not, however, belong
[Seite 143] exclusively to that curious bird11; for I have found
it in the ramphastos, and the corvus caryocatactes (the
nut-cracker).

A deviation from the natural structure, which is
completely unparalleled, occurs in the stomach of
the cuckoo. The gizzard of this bird is covered
internally with an abundance of short, bristly, and
spiral hairs, lying close together.

§ 98. The structure of the stomach differs most
widely in the different orders and genera of this
class. It appears merely as a thin membranous
bag, in several of those which feed on flesh and
insects, when compared with the thick muscular
globes of the granivorous genera. But there are
both many intermediate links12 between these ex-
tremes, and at the same time considerable analogies
on the structures, which are apparently the most op-
posite. This is particularly observable, in the course
of the muscular fibres13,, and in the callous structure
and appearance of the internal coat14; in which
[Seite 144] points, many of what are called membranous sto-
machs, have a great resemblance to those of the
gallinae.

§ 99. Both parts, but particularly the muscular,
are very strong in the gizzard (ventriculus bulbosus)
of granivorous birds15. We find here, instead of
a muscular coat, four immensely thick and powerful
muscles: viz. A large hemispherical pair at the
sides (laterales), and two smaller ones (intermedii)
at the two ends of the cavity. All the four are
distinguished, both by the unparalleled firmness of
their texture16, and by their peculiar colour, from
all the other muscles of the body.

The internal callous coat must be considered as
a true epidermis; since, like that part, it becomes
gradually thicker from pressure and rubbing17. It
forms folds and depressions towards the cavity of
the stomach: and these irregularities are adapted to
each other on the opposed surfaces. The cavity of
this curious stomach, is comparatively small; its
lower orifice is placed very near the upper. Every
part of the organ is, indeed, calculated for producing.
[Seite 145] very powerful trituration18; and this is still further
promoted, by the well-known instinctive practice of
granivorous birds, of swallowing small hard stones
with their food19.

C. Amphibia.

§ 100. The capacious oesophagus of the turtle,
has a very striking peculiarity in its structure: its
[Seite 146] internal coat is beset with1 innumerable large, firm,
and pointed processes of a white colour. Their
points are all directed towards the stomach; and
they probably serve to prevent the return of the
food, which can only enter the stomach gradually.

§ 101. The oesophagus of the crocodile is of the
funnel shape; the stomach of the animal resembles,
although not very closely, that of the granivorous
birds, in the nearness of its two apertures, and the
thickness of its coats.

§ 102. The stomach of serpents can hardly be
distinguished from the oesophagus, except that it is
somewhat larger. It is very short, when compared
with the great length of that tube. (See note (M).

(D) Fishes.

§ 103. The oesophagus is short in most of this
class. But this character is not universal, as Aris-
[Seite 147] totle
supposed2; nor is a long oesophagus pecu-
liar to fishes of an elongated form. (See note (N).

§ 104. The size and form of the stomach vary3
very considerably in this class. Its coats are thin
in most fishes; but in some they are very thick and
muscular4, and have a callous internal covering:
still, however, the resemblance between these and
the stomachs of granivorous birds is very remote.

(E) Insects.

§ 105. I have already observed, on another
occasion5, that the business of nutrition in insects,
does not seem to have for its object, the mere pre-
servation of the individual, as in most red-blooded
animals; but chiefly the consumption of organised
matter; which will appear clearly, from considering
the structure of their alimentary canal. In most of
those, which are subject to a metamorphosis, the
stomach, in the larva state, is of a great size, in
[Seite 148] comparison with the short intestinal canal: while
those on the contrary, which take little or no nou-
rishment in their perfect state, have this organ re-
markably diminished, and as it were contracted2.

§ 106. Our limits will allow us to take but
little notice here of the endless varieties, and pecu-
liarities of internal structure, which occur in the
different genera and species of this multiform class
of animals. We shall therefore only bestow two
words3 on those of the oesophagus and stomach.
In several cases, the commencement and termina-
tion of the alimentary canal, the oesophagus and
rectum, are surrounded by an anular portion of
the spinal marrow.

[Seite 149]

In the earwig (forsicula auricularia), the upper
orifice of the stomach is furnished with two rows
of teeth4.

In some of the grylli (grasshoppers), the stomach
itself is small, but the oesophagus much larger.

In some species of that genus, particularly in the
gryllus gryllotalpa, the stomach consists of three or
four vesicular portions5, which have been com-
pared with the stomachs of the ruminating mam-
malia6.

We have already (§ I, note l.) mentioned the
stomach of the lobster, and some other species of
the genus cancer7; which is provided with several
portions of bone. It contains also three teeth,
which, together with the stomach itself, are annually
reproduced, at least in the craw-fish (cancer astacus),
(See note (O).

(F) Vermes.

§ 107. We can only select a few instances1,
[Seite 150] as examples of this class, which includes a great
number of creatures, differing widely from each
other.

The aphrodite aculeata (sea-mouse), which is
well-known, on account of its beautiful colours,
possesses a very remarkable stomach. The form
and size of the viscus, resemble those of a date,
while in strength and compactness of texture, it
approaches to that of granivorous birds2.

The oesophagus is expanded into a crop in many
testacea, particularly among the bivalves; and it is
covered internally with numerous small teeth3.

[Seite 151]

The powerful stomach of the bulla lignaria, con-
tains three hard calcareous shells, by which the ani-
mal is enabled to bruise and masticate the other
testacea, on which it feeds4.

In most of the proper mollusca, the stomach is of
a simple membranous structure, and of very dif-
ferent comparative magnitudes. I have found it
very large in the scyllaea pelagicum. It occupies the
greatest part of the body in the leech, and is di-
vided internally by means of ten imperfect parti-
tions, into somewhat separate portions.

Lastly, the armed polypes (hydra), and other
similar zoophytes, can hardly be considered as any
thing more than a mere stomach, having its open-
ing furnished with tentacula. (See note (P) at the
end of the chapter.)


Additional Notes to the Sixth Chapter.

(A) A cheek-pouch exists also in the ornitho-
rhynchus paradoxus.
Phil. Trans. 1800, part 1,
tab. 2. fig. 2.

The salivary glands of the mammalia exhibit
[Seite 152] very few variations in structure. They are small in
the carnivora, as mastication, properly so called,
can hardly be said to take place in them. On the
contrary, the ruminantia and solipeda have them
very large. The size of the sub-maxillary gland,
in particular, is remarkable in the cow and sheep:
it extends along the side of the larynx, quite to the
back of the pharynx.

The parotid and sublingual glands do not exist
in the amphibious mammalia, as the seal: the teeth
of that animal are only adapted for seizing their
prey, and must be utterly incapable of mastication.
The same remark may be made on the cetacea, where
the salivary system seems to be altogether deficient.

The mucous glands, which constitute the labiales
and buccales of man, are larger and more distinct
in some animals. There is a row of these opposite
to the molar teeth of the dog and cat, penetrating
the membrane of the mouth by several small open-
ings. Thore is also a considerable gland in the
dog, under the zygoma, and covered by the masse-
ter. Its duct, equal in size to that of the parotid,
or sub-maxillary glands, opens at the posterior ex-
tremity of the alveolar margin of the upper jaw.
The molar glands and their openings, are very con-
spicuous in the pig. The cow and sheep have an
assemblage of similar glands in the zygomatic fossa:
their excretory ducts open behind the last superior
molar tooth.

[Seite 153]

(B) No mammalia possess an uvula, except
man, and the simiae. As the cetacea possess no
nostrils, they have not of course any velum pa-
lati.

The parts about the pharynx exhibit a very
singular structure in these animals. The la-
rynx is elongated, so as to form a pyramidal
production, on the apex of which, its opening is
found. The projection of this part will divide the
pharynx; and the food must pass on either side of
the pyramid. A muscular canal extends from the
pharynx to the blowing holes, and is attached to
the margin of those apertures. The circular fibres
of this tube, form a sphincter muscle; which, by
contracting round the pyramid, cuts off the com-
munication between the blowing holes and the
mouth and pharynx.

(C) In the animals alluded to in this para-
graph, the left half of the stomach is covered
with cuticle, while the other portion has the
usual villous and secreting surface. The cuti-
cular covering, forms a more or less prominent
ridge at its termination. The left portion of
the cavity may be regarded as a reservoir, from
which the food is transmitted to the true di-
gestive organ; and the different states, in
which the food is found in the two parts of the
cavity, justify this supposition. Hence these sto-
machs form a connecting link between those of
[Seite 154] ruminating animals on one side; and such as have
the whole surface villous, on the other.

(D) The larvae of the astrus equi (the large
horse-bot
), attach themselves to every part of the
stomach, but are in general most numerous about
the pylorus; and are sometimes, but much less
frequently, found in the intestines. They hang
most commonly in clusters, being fixed by the
small end to the inner membrane of the stomach,
where they adhere, by means of two small hooks,
or tentacula. When removed from the stomach,
they will attach themselves to any loose membrane,
and even to the skin of the hand; for this purpose,
they draw back their hooks almost entirely within
the skin, till the two points of these hooks come
close to each other; they then present them to the
membrane, and keeping them parallel till it is
pierced through, they expand them in a lateral di-
rection; and afterwards, by bringing the points
downwards, or towards themselves, they include a
sufficient piece of the membrane with each hook,
and thus remain firmly fixed, for any length of
time, without any further exertion of the animal.
They attain their full growth about the latter end
of May, and are coming from the horse from this
time to the latter end of June. On dropping to
the ground, they soon change to the chrysalis, and
in six or seven weeks the fly appears. This bot is
larger and whiter than that of the aestrus hae-
[Seite 155] morhoidalis,
which has a reddish cast; but in its
structure, and situation in the animal, resembles the
former. It is found, however, to hang about the
rectum, previously to quitting it, which the large
horse-bot never does.

Veterinary practitioners do not seem to have de-
cided hitherto, whether these animals are prejudicial
to the horse; nor even whether they may not be
actually beneficial. Their almost universal exist-
ence at a certain season, even in animals perfectly
healthy, shews that they produce no marked ill
effect: yet the holes which they leave, where they
were attached to the stomach, could hardly be made,
without causing some injurious irritation.

For the mode, in which these bots gain admission
into the stomach, as also for a most interesting ge-
neral account of their history and structure, see
Rees’s Cyclopaedia, art. Botts ; which was fur-
nished by Mr. Clarke, and from which the pre-
ceding account is borrowed.

(E) The food of carnivorous animals approach-
ing in its constituent elements more nearly to
those of the animal, than that of the herbivorous
tribes; is more easily reduced into the state, which
is required for the nourishment of the body, in the
former than in the latter case. Hence arises a lead-
ing distinction between the stomachs of these classes.
In the latter animals, the oesophagus opens consi-
derably to the right of the great extremity, so as
[Seite 156] to leave a large cul de sac on the left side of the
stomach; and the small intestine commences near
the cardia, leaving a similar blind bag on the right.
The food must be detained for a long time in such
a stomach, as the passage from the oesophagus, to
the pylorus is indirect and highly unfavourable
to speedy transmission. Animals of the mouse kind,
and the rodentia shew this structure very well; it
is very remarkable in the mus quercinus, (Cuvier
Leçons, &c. tom. 5. pl. 36. fig. 11.) In the car-
nivora,
the stomach, which is of a cylindrical form,
has no cul de sacs; the oesophagus opens at its
anterior extremity, and the intestine commences
from the posterior; so that every thing favours a
quick passage of the food. Animals of the weasel
kind, which are very truly carnivorous, exhibit
this structure the most completely. The seal also
exemplifies it: and the lion. (Cuvier, pl. 36.
fig. 7).

(**) The peculiar structure of the stomach in
the camel and lama, which enables these animals
to lake at one time a sufficient quantity of water
to last them for two, three, or more days, and
thereby renders them adapted to inhabit the dry
and sandy deserts, which constitute their natural
abode, has been entirely omitted by the author.
The fluid, which they drink, is deposited in nume-
rous cells formed in the substance of their first and
second stomachs, by strong bands of muscular
[Seite 157] fibres crossing each other at right angles. It should
seem that the animal has the power of closing these
cells, by the contraction of those fibres which form
the mouths of the cavities; or of expelling the
contained fluid by putting the other portions of
fibres in action.

This cellular structure is found in two parts
of the first stomach; and it occupies the whole of
the second. It was found in a dead camel, that
these cavities would hold two gallons of fluid:
but they were probably more capacious during
life, as the animal in question always drank six or
seven gallons of water every other day, and took
more in the intermediate time. Mr. Bruce states
in his travels, that he procured four gallons
from one which he slaughtered in Upper Egypt.
(Shaw’s Abridgment of Bruce’s Travels, ed. 3.
p. 371).

As all the food which the animal takes passes into
the first stomach, the water of the cells in that part
becomes turbid; but it remains perfectly pure in the
second, where it resides in the greatest quantity:
which circumstance accounts for travellers being
able to drink it on an emergency. The muscular
bands, which form the groove described at § 90,
are particularly strong; and by drawing the third
stomach to the oesophagus, convey the ruminated
food through the second, without polluting the
water in its cells. Hence the food that has been
macerated in the paunch must be sent back to the
[Seite 158] mouth directly from that cavity, without passing
into the second stomach, as it does in the cow. See
‘“Observations on the camel’s stomach, respecting
the water which it contains,”’ &c. by E. Home,
Esq. Philos. Trans. 1806.

The cells are described and delineated, but very
imperfectly, by the Parisian dissectors. Description
Anatomique,
&c.p. 80.

The structure of these parts, in the lama, accord-
ing to the account which Cuvier has given of
them, from the examination of a fetus, does not
seem to differ essentially from that of the camel.

Léçons d’Anat. Comp. tom. 3. p. 397.

Mr. Home also describes a projecting glandular
body in the fourth stomach, near the pylorus, both
in the cow and camel. He states that it may
shut that aperture. The same body is represented
as very large in the lama, by Cuvier loc. cit.

(F) According to Cuvier, there is a gland, as
large as the head of a man, situated between the
the coats of the stomach in the manati (tricheus
manatus borealis
). It is placed near the oesophagus,
and discharges, on pressure, a fluid like that of the
pancreas by numerous small openings.

Léçons d’Anat. Comp. tom. 3. p. 401.

Mr. Home is of opinion, that a glandular struc-
ture exists in the stomach of the sea-otter near the
pylorus. Philos. Trans. 1796. pl. 2. And Mr.
Macartney has discovered an arrangement of
[Seite 159] glandular bodies in the dormouse, round the oeso-
phagus just before its termination, similar in situa-
tion and appearance to the gastric glands of birds.

(G) The stomach of the ornithorhynchus hystrix
is covered with cuticle, and possesses sharp horny
papillae near the pylorus. The animal swallows
sand, which may probably assist in the reduction of
the food, as the gravel does, which is swallowed by
the gallinaceous birds. Home in the Philos. Trans.
1802. p. 2.

(H) A very remarkable dilatation of the fauces
occurs in the pelican. An immense pouch, capable
of holding several quarts of water, lies between the
branches of the lower mandible, and constitutes
a reservoir for the food, which consists of fishes.
By means also of this bag, the animal seeds its
young, until they are of sufficient strength to pro-
vide for themselves.

(I) Proper salivary glands, such I mean, as se-
crete that clear and limpid fluid constituting the
saliva, do not exist in birds. For mastication, or
the comminution of the food, and its reduction
into a soft paste, to which function these glands are
entirely subservient, is not performed in the mouth
these animals, but in their gizzard. Birds
however have a very copious apparatus of those
mucous follicles, which form the glandulae labiales,
[Seite 160] buccales, linguales, &c. of the human subject. The
sides of the tongue, the under surface of that organ,
and the entrance of the oesophagus, are beset with
numerous openings of these glands, which furnish an
abundant supply of viscid mucus to defend the
tender lining of these parts from the hard bodies,
which constitute the food of several birds. These
apertures are very conspicuous in the gallinae.
The ostrich in particular, has two flattened bodies
at the upper and back part of the palate, which
may be compared in some respects to tonsils. The
surface of these is covered with innumerable fora-
mina, from which a tenacious mucus may be ex-
pressed. The soft palate, &c. are entirely deficient
in birds: the nostrils open on the bony palate by
longitudinal slits, the sides of which are guarded
by soft pointed papillae.

(K) The crop of the common fowl, and of the
other gallinae, is of a globular form, and placed
just in front of the chest. The oesophagus, which
opens at its upper part, commences again about
the middle of the bag, so that the crop itself forms
a cul de sac, or bag out of the regular course of
communication between the two openings of the
oesophagus. In the pigeon there is a spherical bag
formed on both sides of the oesophagus; which tube
itself is very large in the pouting pigeon, and admits of
being distended with air, so as to cause the appear-
ance from which the name of the bird is derived.
[Seite 161] In the birds, which we have now mentioned, the
crop must be considered as an organ for macerating
the dry and hard vegetable substances, which con-
stitute the food of these animals. The accipitres
also have this dilatation; but it must be regarded
in them merely as a reservoir for the food, which
does not require any previous softening. It is want-
ing in the piscivorous birds; but its place is sup-
plied by the great size of the oesophagus, in which
entire fishes are held until they can pass into the
stomach. The heron, cormorant, &c. exemplify
this.

(L) The term bulbus glandulosus (ventricule suc-
centurié,
Cuvier) is applied to a small portion of
the oesophagus, just before its termination in the
stomach. This part is obviously rather larger and
thicker in its coats than the rest of the tube. Its
structure may be most clearly discerned in the gal-
linaceous genera. The oesophagus consists, as in
other parts, of its two coats, the muscular and
villous: but a vast number of glandular bodies,
cylindrical in form, and arranged in close apposi-
tion to each other, are interposed between these
tunics, and entirely surround the tube; constituting
the ‘“zone of gastric glands”’ of Mr. Macartney,
(Rees
’s Cyclopaedia, Art. Birds). These bodies
have a hollow internally, and they open into the
cavity of the bulbus. The fluid secreted by them,
which from their number and size, must be furnished
[Seite 162] in great abundance, passes into the gizzard, and
mixes with the food in proportion as it is triturated
by that organ. These glands are much less distinct
in those birds which live on animal food, as the
accipitres, and the piscivorous genera, but they exist
universally, and their openings can always be dis-
cerned. The ostrich affords an opportunity of ex-
amining them to great advantage. In the African
species, of which I dissected an individual, the
oesophagus was dilated into an immense bag, capa-
ble of holding several pints of water, and five or
six times larger than the gizzard itself, which was
placed on the right and anterior part of this dilata-
tion. The glands did not surround the tube, so
that the term of zone would be here inapplicable.
They formed a long but narrow band, commencing
at the termination of the oesophagus, and running
along the front of the bag towards the gizzard.
This band measured about twelve inches in length,
and not more than three at its greatest breadth.
The size of the individual glands varied: they were
largest in the middle, and decreased towards either
margin of the band. Some of them equalled a
large pea; and their openings were in proportion.
They were arranged in close apposition to each
other, and the inner surface of the pouch was
covered by a continuation of the insensible lining
of the gizzard, which separated very easily from
the surface.

[Seite 163]

(M) Reptiles resemble birds in having their
nostrils terminate by two longitudinal slits on the
palate; and in the want of velum palati, and
epiglottis.

The oesophagus of the serpent kind is of im-
mense magnitude; for these reptiles swallow ani-
mals larger than themselves, which are retained for
a considerable time in the tube, and descend into
the stomach by degrees, where they are slowly sub-
jected to the action of the gastric juice. The whole
process sometimes occupies many days or even
weeks.

(N) From the peculiar formation of the nose
of fishes; and from their respiring by means of
gills, their fauces have no connexion with any
nasal cavity, or glottis.

The oesophagus is of great width in fishes; and
is distinguished with difficulty in many cases from
the stomach. These animals swallow their food
whole, without subjecting it to any mastication;
and if the stomach will not hold the whole, a part
remains in the oesophagus, until that, which has
descended lower, is digested. The alimentary
canal is generally very short; sometimes extending
straight from the mouth to the anus with very
little dilatation; as in the lamprey (Petromyzon
marinus
).

[Seite 164]

(O) The crustacea, and some insects, are fur-
nished with organs of mastication of similar structure.
Their mouth is formed of two or more pairs of
jaws placed laterally. These move from without
inwards, and vice versâ; whereas those of red-
blooded animals move from above downwards,
and back again. The parts, which are termed
the lips of insects, are two bodies; of which one
is placed above or in front of the jaws, and the
other below or behind them. The palpi or feelers
are articulated to the jaws. All insects, which
have jaws, possess the power of masticating hard
animal and vegetable substances; for these parts
are of a firm horny texture, and in many cases are
very large, when compared with the size of the
animal.

The locusts (grylli), the dragon-fly (libellula),
the beetles, and particularly the lucanus cervus, or
stag-beetle, and the staphylinus maxillosus, are ex-
amples in which the jaws are very large and mani-
fest, and often possess denticulated edges. All the
genera of the following orders have jaws; viz. the
coleoptera, orthoptera, neuroptera and hymenoptera.
The insects of the remaining orders derive their
nourishment chiefly from liquids; which they get
either from animal or vegetable substances by
means of a spiral and tubular tongue, or a soft
proboscis, (as in the lepidoptera), with a broad
opening, admitting of extention and retraction,
[Seite 165] (the hemiptera), or a horny pointed tube, contain-
ing sharp bristly bodies internally (the diptera and
aptera).

The stomach of the bee is a transparent mem-
branous bag, in which the nectar of the flowers is
elaborated and converted into honey. The animal
vomits it up from this reservoir, and deposits it in
the hive.

The stomach of the crab and lobster is a very
singular organ. It is formed on a bony apparatus,
in short a species of skeleton; and does not there-
fore collapse when empty. To certain parts of
this bony structure, round the pylonus, the teeth
are affixed. Their substance is extremely hard,
and their margin is serrated or denticulated: as
they surround the tube, near the pylorus, nothing
can pass that opening, without being perfectly com-
minuted. These bones and teeth are moved by
peculiar muscles.

(P) In those mollusca, which possess jaws, these
parts are fixed in the flesh of the animal, as there is
no head to which they can be articulated. They are
two in number in the cuttle-fish, are composed of
a horny substance, and resemble exactly the bill of
a parrot. They are placed in the centre of the
lower part of the body, and are surrounded by
the tentacula, which enable the animal to attach
itself to any objects. By means of these parts, the
shell-fish, which are taken for food, are completely
[Seite 166] triturated. The common snail and slug have a single
jaw, semilunar in its form, and denticulated. The
tritonia has two jaws, which act like the blades of a
pair of scissars. The other mollusca possess no or-
gans of this kind; but have, in some instances, a
sort of proboscis; as the buccinum, murex, voluta,
doris, scyllaea,
&c.

In the worms, properly so called, there are some-
times hard parts forming a kind of jaws or teeth.
Thus in the nereis, the mouth possesses several cal-
careous pieces. The aphrodite (sea-mouse), has a
proboscis, furnished with four teeth, which it can
extend and retract at pleasure. Within the mouth
of the leech are three semicircular projecting bodies,
with a sharp denticulated edge: by this apparatus
the animal inflicts its wound of the well-known
peculiar form in the skin.

The teeth of the echinus, (sea-hedgehog) are of a
very singular arrangement; a round opening is
left in the shell for the entrance of the food; a
bony structure, on which five teeth are placed, fills
up this aperture; and as these parts are moved by
numerous muscles, they form a very complete or-
gan of mastication.

The stomach of the vermes is, in general, a mem-
branous bag; but in some cases its structure is
more complicated. In addition to the instances
mentioned by the author, we may observe that
the helix stagnalis, and the onchidia, have gizzards.
The aplysia has three strong muscular stomachs,
[Seite 167] provided with pyramidal bony processes. This
structure, together with that of the bulla lignaria,
and of the lobster and crab, presents a new analogy,
as Cuvier, has observed, between the membranes
of the intestines, and the integuments of the body.
This is particularly strengthened by the annual
shedding of the lobster’s teeth, when its crustaceous
covering falls off.

CHAPTER VII.
ON THE INTESTINAL CANAL.

[Seite 168]

(A) Mammalia.

§ 108. The intestinal canal (which is the most
common part in the whole animal kingdom after
the stomach), is distinguished in this class, by two
peculiarities, which depend on the mode of nu-
trition. It is comparatively shorter in carnivorous
animals,
and there is also in these, less difference to
external appearance, between the small and the
large intestine, than in the herbivora. Yet these
rules are not without their exceptions. For the
seal has very long, and the sloth very short intes-
tines; the badger, which is not a proper carnivo-
rous animal, and several true herbivora, as, for
instance, the rell-mouse (glis esculentus), have no
distinction between the large and small intestine,
&c. (See note (A) at the end of the chapter).

§ 109. The valvulae conniventes of the small
intestine are more faintly marked in most mam-
malia than in man; in some indeed they do not
exist at all, and this happens both in carnivorous
[Seite 169] and herbivorous animals. In the cetacea, on the
contrary, the internal surface of the intestines has
longitudinal folds of a zig-zag appearance.

The possession of a villous coat for the absorption
of the chyle constantly distinguishes the small from
the large intestine, which seems to be merely
destined for the reception of the faeces. The villi
are remarkably long and numerous in the bear*.

The Fallopian valve (valvula coli) is wanting in
a few animals only of this class, as, for instance,
in the hedgehog1.

§ 110. There is great variety with respect to
the caecum in this order, even in the different
species of the same genus. Many, particularly of
the carnivora, have none; it is also wanting in
some herbivora, as the rell-mouse. In others of the
latter description, it is often of enormous size.
Thus in the hare and rabbit it is longer than the
whole animal, and furnished internally with a pecu-
liar spiral valve. The marmot of the cape has first
[Seite 170] a large caecum, and then, further on, two other
conical blind appendices.

The appendicula vermiformis is wanting in many
mammalia; even in some of the simiae. (See note
(B) at the end of the chapter.)

§ 111. In most herbivorous animals of this
class, the colon is large, long, and divided into
cellular compartments. This is remarkably the
case with the elephant and horse. The large in-
testine of the latter is 24 feet long; while, on the
contrary, in a moderate sized dog it is about six
or eight inches. The rectum of the latter has
strong transverse folds which contract it, and ren-
der the evacuation of the faeces difficult.

In a few instances, as the beaver and sloth, the
rectum and urethra have a common termination,
which may be compared to the cloaca of birds2.
[Seite 171] This similarity is however the most striking in
the cloaca of the ormithorhynchus. (Home in
the Philos. Trans. for 1802, pl. 1.)

(B) Birds.

[Seite 172]

§ 112. The alimentary canal, in this class, is
much shorter than in the mammalia; it is also ge-
nerally shorter in carnivorous birds than in such as
derive their food from the vegetable kingdom.
There is hardly any perceptible external difference
between the large and small intestine; indeed, the
commencement of the canal is often larger than the
termination.

§ 113. Most birds have two caeca, which are of
considerable length in some species of the gallina-
ceous and aquatic birds. They are characterized
in the ostrich3, by a remarkable spiral valve. Some
few aquatic birds have only a single caecum; and
some, particularly among the birds of prey, want it
entirely.

§ 114. The rectum ends in a part called the
cloaca; which is an expanded portion, containing
[Seite 173] the terminations of the ureters, the genital organs,
and the bursa Fabricii. This latter part varies in
form in the different species, being oval, or elon-
gated, &c.; it is largest in young birds, and is so
contracted in older ones, that it will hardly hold a
millet-seed4 in an old cock. (For a further ac-
count of it, see note (C) at the end of the chapter).

(C) Amphibia.

§ 115. We shall take only one species of each
of the two chief divisions of this class, by way of
examples.

The intestinal canal of the hawksbill turtle (tes-
tudo caretta
), is five times as long as the whole
animal; the small intestine, as it is called, is larger
than the short portion of large intestine. Both
portions have longitudinal5 folds internally, and
are covered with an abundance of mucus6, (which
is the case in the whole class).

[Seite 174]

§ 116. In the coluber natrix, the whole length
of the intestinal canal does not equal that of the
animal. The small intestine forms a very consider-
able fallopian valve, by a prolongation at its en-
trance into the large. The termination of the small,
as well as the large intestine, the stomach, and
oesophagus (which is one-third of the length of the
whole animal) have longitudinal folds7 internally.

(D) Fishes.

§ 117. The intestinal canal of this class, with a
very few exceptions, is extremely short. In some,
as the torpedo8, it is only half as long as the sto-
mach. However, the passage of the chyle, and
afterwards of the faeces, through the intestine, is
lengthened in this, and some other cartilaginous
fishes, by a spiral valve9*.

[Seite 175]

§ 118. The appendices pyloricae, (which are found
in all fishes, with a very few exceptions, as the pike)
sometimes open at the lower orifice of the stomach,
hut generally at the commencement of the intestinal
canal, and secrete a fluid, which seems to have con-
siderable influence on the business of digestion and
chylification10, which is performed in these animals
in a very short time. They have generally the ap-
pearance of small blind appendices11, and their
number varies in the different species, from one to
several hundreds. In some cartilaginous fishes, they
are, as it were, consolidated into a glandular body12,
which has been compared to the pancreas of warm-
blooded animals.

(E) Insects.

§ 119. Similar blind appendices (vasa varicosa
of Swammerdam), are found on the short alimen-
[Seite 176] tary canal of several insects13; which is particularly
distinguished from that of red-blooded animals, by
the want of mesentery14.

(F) Vermes.

§ 120. Several mollusca have these appendices
on both sides of their short intestinal tube, viz. the
aphrodite aculcata. Those testacea, which remain
fixed in one situation, have a shorter and more
simple intestinal canal than those which have the
power of locomotion. The rectum, according to
Poli, passes directly through the heart in most of
the bivalves. In the slug (limax), as well as in the
similar animal, which inhabits a shell (helix), the
rectum opens on the front of the limbus, close to the
air-hole. The leech can hardly be said to possess
an intestine; yet it has an anus at the end of the
tail, from which some little fecal matter is dis-
charged, most of this being evacuated by the mouth.
The armed polypes have no opening of this kind15.

Additional Notes to the Seventh Chapter.

[Seite 177]

(A) In considering the proportionate lengths of
the intestinal canal, and the relation which these
bear to the kind of food, on which the animal sub-
sists, many circumstances must be taken into the
account, besides the mere measure of the intestine.
Valvular projections of the internal membrane;
dilatations of particular parts of the canal; and a
large general diameter, compensate for shortness of
the intestine; and vice versa. The structure of the
stomach must also be considered; as, whether it is
formed of more than one cavity; whether the
oesophagus and intestine communicate with it in
such a manner, as to favour a speedy transmission
of the food; or, whether there are cul de sacs,
which retain the aliment for a long time in the
cavity. The formation of the jaws and teeth, and
the more or less perfect trituration and comminu-
tion, which the food experiences in the mouth, must
likewise be viewed in connection with the length
and structure of the alimentary canal.

The whole length of the canal is greater in the
mammalia than in the other classes. It diminishes
successively, as we trace it in birds, reptiles, and
fishes, being shorter than the body in some of the
latter animals, which is never the case in the three
first classes.

[Seite 178]

In omnivorous animals, the length of the canal
holds a middle rank between those which seed on
flesh, and such as take vegetable food. Thus, in
the rat, its proportion to the body is as 8 to 1; in
the pig 13 to 1; in man 6 or 7 to 1. The dimi-
nution in length, in the latter case, is compensated
by other circumstances, viz. the numerous valvulae
conniventes, and the preparation which the food
undergoes, by the art of cookery.

In carnivorous animals, every circumstance con-
curs, to accelerate the passage of the alimentary
matter. It receives no mastication; it is retained
for a very short time in the stomach; the intestine
has no folds or valves; it is small in diameter;
and the whole canal, when compared to the body,
is extremely short, being 3 or 5 to 1.

The ruminating animals present the opposite
structure. The food undergoes a double mastica-
tion, and passes through the various cavities of a
complicated stomach. The intestines are very long;
27 times the length of the body in the ram. Hence
the large intestines are not dilated, or cellular;
nor is there a caecum. The solipeda have not such
a length of canal, nor is their stomach complicated;
but the large intestines are enormous, and dilated
into sacculi: and the caecum is of a vast size; equal,
indeed, to the stomach. The rodentia, which live
on vegetables, have a very large caecum, and a ca-
nal 12 or 16 times as long as the body. In the
rat, which can take animal, as well as vegetable
[Seite 179] food, the canal is shorter than in the other ro-
dentia.

There are some exceptions to the rule, which we
have just mentioned, respecting the length of the
canal in carnivorous and herbivorous animals. The
seal, which takes animal food, has very long intes-
tines: the sea-otter resembles it in this respect, and
differs therein most remarkably from the common
otter, which resembles other carnivorous animals
in the shortness of its intestinal tube. The length
of canal in the former, is twelve times that of the
animal; and only three times and a quarter in the
latter. (Home, in the Philos. Trans. 1799, part 2.)
Whales have likewise a longer canal than other car-
nivorous mammalia; their stomach is complicated,
and the intestine has longitudinal folds. It seems,
therefore, that a considerable length of intestinal
canal is found in all mammalia, which live much in
the water, although they are carnivorous.

The plantigrade animals, which have carnivorous
teeth, but feed equally well on vegetables, have a
long canal: but it is very narrow, and possesses no
caecum, nor distinction of large intestine.

A species of bat (vespertilio noctula), seems to
have the shortest intestinal canal of any mammalia:
it is only twice the length of the animal’s body.
On the contrary, the roussette (vesp. vampyrus
Linn. v. caninus Blum.) which lives entirely on
vegetables, has it seven times as long.

A remarkable difference is observed, in the length
[Seite 180] of the canal between the wild and domesticated
breeds of the same species. In the wild boar the
intestines are to the body as nine to one; in the
tame animal, these proportions are as thirteen to
one. In the domestic cat, five to one; in the wild
cat,
three to one. In the bull twenty-two to one;
in the buffalo, twelve tb one, They are, on the
contrary, longer in the wild than in the tame
rabbit; the proportions in the former being eleven;
and in the latter nine to one.

The proportion of the intestinal canal to the
length of the body in birds, is as two, three, four,
or five to one. It is not always longest and largest
in the graminivorous species; as many piscivorous
birds have it equally long.

It is hardly twice the length of the body in
many reptiles; and not so much in the frog, al-
though it is nine times as long as the space between
the mouth and the anus in the tadpole.

The alimentary canal of some fishes, is continued
straight from the mouth to the anus, and does not
therefore equal the length of the body. The
lamprey, skate, and shark are thus circumstanced.

(B) Most of the animals, which have a vertebral
column, have the intestine divided into two parts;
viz. the large and small. The latter is commonly
the longest, smallest; in its diameter, and villous on
its internal surface. The former is often thicker in
its coats, and very rarely villous. In those mam-
[Seite 181] malia, which have this distinction, the separation is
marked by one or more appendages, which have
the name of caecum when large, of vermiform appen-
dix
when slender. Man, the orang-outang, and the
phascolome (a species of rat having an abdominal
pouch, from New Holland,) are the only animals,
which have both coecum and appendix. The orni-
thorhynchus histrix
has an appendix only: and
most other mammalia have only a caecum. All
the simiae, except the orang-outang, have a caecum,
like that of man, but want the appendix vermi-
formis.

Several possess neither caecum nor appendix,
as the edentata, (except the proper ant-eaters); the
tardigrada, the bats, the plantigrada, except the
ichneumon, the mustelae, and the myoxi (dormice);
and the cetacea.

A valvula coli shews the distinction between the
large and small intestine, where the coecum is want-
ing: as in the sloth and armadillo. When this dis-
tinction does not exist, the large intestine is cha-
racterised by the want of villi, by a greater thick-
ness of its coats, and particularly by a strong layer
of longitudinal muscular fibres.

In animals, which have a coecum, this part ap-
pears to be merely a prolongation of the large in-
testine below the termination of the small. Yet
in some cases, the large intestine retains only for a
short space, the same structure, which the coecum
possessed, as in the flying lemur (galeopithecus), the
[Seite 182] opossum, most of the rodentia and ruminantia. In
the herbivorous mammalia, the caecum is generally
large and cellular; and it is even so in omnivorous
animals, as in man, in the genus simia, and lemur.
In the ruminantia, where the stomach is very com-
plicated, the caecum is of a moderate size, and uni-
form. It is large and cellular in the flying lemur,
and opossum, which are supposed to live much on
animal substances.

The caecum of the true carnivorous mammalia
is constantly small, and uniform in its cavity; and
the rest of the large intestine has the same cha-
racters. The large intestine of the herbivora is
cellular; excepting the ruminantia, and some of
the rodentia.

It may therefore be stated as a general rule, that
the existence of a large caecum shews that the
animal seeds on vegetables: and that carnivorous
mammalia have either none, or a very small
one.

The ornithorhynchus paradoxus and hystrix have
the end of the rectum forming a cloaca as in birds.
The urinary bladder opens into this part. The
penis of the male is contained within it; and the
horns of the uterus open into it in the female.
Home in the Philos. Trans. 1802, pt. 1. of the
o. paradoxus, pt. 2. of the o. hystrix.

(C) The bursa Fabricii is an oval membranous
bag; situated at the upper or back part of the
[Seite 183] cloaca, into which it opens by a slit-shaped aperture.
Its size is proportionate to that of the animal; be-
ing one inch and a quarter long in the goose, and
half an inch broad: and about a quarter of an inch
in length in the sparrow. According to the accu-
rate observations of Mr. Macartney, its coats con-
tain numerous glandular bodies, which furnish a
mucous secretion. (Article Birds in Rees’s Cy-
clopaedia).

(D) In the structure and formation of the coats
of the intestinal canal, there are not many diffe-
rences in the mammalia. True valvula conniventes
seem peculiar to man and the monkeys. But the
internal surface of the intestine is always villous,
and generally deserves that appellation more than
in the human subject. Some of the carnivora, as
the dog, have very long villi: and this class has in
general more muscular intestines. A considerable
number of mucous glands is found near their
caecum, when they have one. But the seal has
these glands in greatest number, and most distinct.
They form, in that animal, a regular and unbroken
series through the whole length of the lower por-
tion of the small intestine; and are very visible
on account of their colour.

The villous coat of the intestine forms numerous
oblong processes in the rhinoceros. (Philos. Trans.
1801. pt. 1.)

[Seite 184]

The villi in the small intestine of birds are remark-
ably long, numerous and elegant. They are most dis-
tinct, and clearly developed in the graminivorous
birds. In the ostrich they are rather flat thin laminae
than villi; but at the same time long and numerous,
so as to present a very elegant structure. The
large intestine of birds is uniform on its surface;
but the ostrich presents a very remarkable devia-
tion, for its large intestines, which are very long,
have numerous transverse folds like the valvulae
conniventes of man.

The intestine of the turtle is covered with innumer-
able thin longitudinal processes, lying close together,
and increasing the surface of the gut to a vast extent.
These are most numerous in the upper part of the
intestine, and gradually diminish in number below,
until they cease altogether. In this respect they
resemble the valvulae conniventes of man; and
the villi of all animals. For these structures are
always most distinct at the commencement of the
canal, where absorption of the chyle goes on to
the greatest extent. As the alimentary matter be-
comes deprived more and more of its nutritious
parts, as it descends in the intestine, a less com-
plicated apparatus for absorption exists in the
lower part of the canal, and is sufficient for taking
up the small remains of really nutritious parts.
This circumstance is illustrated in the longitudinal
folds of the cetaceous animals. At the commence-
[Seite 185] ment of the intestine, there are four or five of
these: at different distances we meet with four,
three, two, one, and lastly the surface is completely
uniform.

(E) As the part of his work, which the author
has devoted to the alimentary canal of the lower
orders of animals, is very short, and as the subject
is interesting in many points of view, it seems right
to subjoin a somewhat more ample account.

The simple globular hydatid, which is frequent-
ly found in the different viscera, both of man and
quadrupeds, has been supposed by some to be an
animal consisting entirely of a stomach. Doubts,
however, have lately been raised, whether or no
this be really an animal. The reader, who wishes
to see the arguments on both sides of the question,
may consult the ‘“Observations on the Manner in
which Hydatids grow and multiply in the Human
Body,
”’ by J. Hunter, M.D. in the 1st vol. of
the Transactions of a Society for the Improvement of
Medical and Chururgical Knowledge;
and the note
to the 82d paragraph of this work. Even if it were
allowed that these bags are animals, it does not
follow that their cavity is a stomach; and the
attachment of the young to the sides would rather
justify us in considering it as the organ of genera-
tion.

The hydatid, which is more frequently found in
[Seite 186] animals; which possesses a head and mouth like the
taenia, enabling it to attach itself to parts, and
which can be seen to move when placed in warm-
water, is generally allowed to possess an inde-
pendent vitality. But whether the bag of water,
which forms its body, be a stomach, is certainly
doubtful.

The most simple form of an alimentary cavity
exists in the common fresh-water polype (hydra).
It appears to be excavated in the substance of the
body, and has a single opening, situated in the
centre of the space surrounded by the tentacula.
The nutritive matter soaks immediately into the
body, and imparts its colour to the animal.

The large masses of gelatine, called medusae,
which resemble in form mushrooms, and are found
floating in the sea; have a somewhat similar struc-
ture. A stomach is hollowed out in the pedicle;
and vessels, commencing from its cavity, convey
the nutritious fluid over the body. Sometimes the
stomach has a simple opening: in other cases there
are branching tentacula, on which canals commence
by open orifices; these unite together to form
larger tubes, and the successive union of these
vessels forms at last four trunks, which open into
the stomach, and convey the food into that cavity.
This very singular structure constitutes a remarka-
ble analogy to the roots of trees; and Cuvier has
formed a new genus under an appellation derived
[Seite 187] from this comparison; viz. the rhizostoma, from
‘ριζη a root, and ςομα a mouth.

The star-fish (asterias) has a membranous
cavity in the centre of its body, communicating
externally by a single opening. Two canals ex-
tend from this into each of the branches, or as
they sometimes called the fingers of the animal,
where they subdivide, and form numerous blind
processes.

The tape-worm (taenia) has a small canal run-
ning on each side of its body: the two tubes are
joined together by transverse productions at each
joint.

The ascaris lumbricoides (round-worm) has a sim-
ple canal running from one extremity of the body
to the other.

The leech (hirudo sanguisuga or medicinalis) has
a short oesophagus and a very large stomach, divided
by numerous membranous septa, which are perfo-
rated in the centre. It has been generally sup-
posed that this animal has no anus; but Cuvier
fays, that it possesses a very small one. (Leçons
d’Anat. Comp.
tom. 4. p. 141.): Dumeril, on
the contrary, denies its existence. (Zoologie Ana-
tique,
p. 298.)

The common earth-worm (lumbricus terrestris)
has a long canal, divided by several partitions.

The aphrodite aculeata has an intestine running
according to the length of the body, and sending
[Seite 188] off on each side several blind processes, which en-
large at their termination.

In the proper mollusca, besides the stomach,
which has been already noticed there, is an intes-
tine, seldom of considerable length, making some
turns in its course: it passes in all the acephalous
mollusca through the heart.

The intestinal canal of insects varies very much
in the different genera and species. It may be
stated on the whole, that a long and complicated
intestinal tube, denotes that the insect feeds on
vegetables; while the contrary characters indicate
animal food.

Great difference is found, in some instances,
between the larva, and the perfect insect. The
voracious larva: of beetles, (scarabaei), and but-
terflies, have intestines ten times as large as
the winged insects, which are produced from
them.

In the dragon-fly (libellula), which is very carni-
vorous, the intestine is not longer than the body.
There is a small but muscular stomach.

The orthoptera, (which class contains the locusts,
&c, well known for their destructive powers,)
have a long and complicated alimentary appa-
ratus. They have first a membranous stomach.
This is succeeded by another cavity covered in-
ternally with scales or teeth, and possessing a very
thick muscular coat; in short, a true gizzard.
[Seite 189] Round the end of this the caecal processes are
attached. There is, lastly, an intestinal canal
differing in length and diameter.

The aliamentary canal runs straight along the
body in the crustacea, and is uniform in its dimen-
sions, excepting the stomach.

CHAPTER VIII.
ON THE LIVER, SPLEEN, AND OMENTUM.

[Seite 190]

§ 121. We may conveniently collect together,
in this chapter, whatever is to be said concerning
the liver, spleen and omentum; since these parts
are connected with each other in their functions.

The spleen and omentum seem to be less con-
stantly found in the animal kingdom, than the
liver, and to be in a manner subservient to the lat-
ter viscus: which, on the contrary, exists in every
class and order of animals that is provided with a
heart and circulating system.

(A) Mammalia.

§ 122. Besides the less important, and indeed
constant variations in size, colour, division into
lobes1, &c., the liver of these animals is dis-
[Seite 191] tinguished by two chief differences: first, in some
genera and species it transmits all the bile immedi-
ately into the duodenum. Secondly, in several others
a part of this fluid is previously collected in the
gall bladder. Animals of the horse2 and goat kind,
and the cetacea afford instances of the want of this
receptacle.

On the contrary in some of those which have
it, there are hepatico-cystic ducts, which convey the
bile immediately from the liver into this bladder:
as in the horned cattle. (See note (A) at the end
of the chapter).

In the ox and sheep, the spleen is distinguished by
a peculiar cellular3 structure from the merely vas-
cular texture which it possesses in other animals of
this class.

Mammalia alone4 possess a true and proper omen-
tum. And the part, which has been called a
[Seite 192] spleen in other animals is very different in its struc-
ture, connections, &c. from the same viscus as it
exists in this class.

(B) Birds.

§ 123. The liver is much larger in domesti-
cated, than in wild birds5. It is well-known that the
gall-bladder is wanting in many species of this class,
(for instance in the pigeon, parrot, &c.): and some
times in particular individuals of a species, which
commonly has it; as in the common fowl. (See note
(B) at the end of the chapter).

A roundish lump of fat, which covers the in-
testines pf some aquatic birds, has been considered
as an omentum.

(C) Amphibia.

§ 124. The liver, in these animals, is universal-
ly of considerable size; and in some instances, as
[Seite 193] the salamander, of immense magnitude. I know
no species in which the gall-bladder is wanting.

The yellow appendices, (ductus adiposi, appen-
dices luteae
) which are found in the frog, on either
side of the spine, and sometimes form one mass,
sometimes are divided into several smaller portions,
were considered by Malpighi as a kind of omen-
tum6. That this resemblance is very remote, ap-
pears from several circumstances; and particularly
from the constant and remarkable variations of size
which occur in these parts at the pairing season.

(D) Fishes.

§ 125. In many animals of this class, the
short intestinal canal is surrounded, and as it were
consolidated with a long liver. Some fishes, which
are almost destitute of fat in the rest of their
body, have an abundance of oil in the liver; as,
for instance, the skate and cod. It is wanting in
some few species. (For an account of the situation
of the spleen, see note (C) at the end of the
chapter).

(E) Insects.

§ 126. An organ secreting bile, and which
[Seite 194] may therefore be regarded as a liver, is found in
such animals only of this class, as have a heart and
system of vessels; viz. in the genus cancer7. We
have already observed (§ 119. – note 12), that the
blind appendices, found in several others, have
been considered as biliary organs. See note (D).

The large adipose substance, which occupies the
greatest part of the body of larvae, and of several
insects, has appeared to some zootomists to resem-
ble the omentum8.

(F) Vermes.

§ 127. The organs, which secrete and contain
the fluid of the cuttle-fish, have been regarded as of
a biliary nature. Thus the mytis has been called
the liver, and the ink-bag the gall-bladder9.

Several testacea, particularly among the bivalves,
have a liver surrounding their stomach, and pour-
ing its bile into the cavity10 of that organ. In
[Seite 195] many snails it occupies the upper turns of the
shell11*.


Additional Notes to the Eighth Chapter.

(A) The liver of mammalia is in general divided
into more numerous lobes; and the divisions are
carried deeper into its substance, than in the hu-
man subject. This is particularly the case in the
carnivora, where the divisions of the lobes extend
through the whole mass. But the utility, which
Monro has assigned to this structure; viz. that of its
allowing the parts to yield and glide on each other
in the rapid motions of the animal, carries very
little plausibility with it. (Essay on comparative
Anatomy,
p. 11.)

In many animals of this class, as the horse, the
ruminantia, the pachydermata, and whales, the
liver is not more divided than in man.

The ductus choledochus forms a pouch between
[Seite 196] the coats of the intestine, for receiving the pancrea-
tic duct, in the cat and elephant.

All the quadrumana, carnivora, and edentata have
a gall-bladder.

Many rodentia, particularly among the rats,
want it. The tardigrada; the elephant, rhinoceros,
and pecari among the pachydermata; the genus
cervus and camelus among the ruminating ani-
mals; the solipeda; the trichecus and porpoise also
want this part. It does not exist in the ostrich and
parrot; but is found in all the reptiles. Cuvier
thinks that it belongs particularly to carnivorous
animals; that it is connected with their habit of
long fasting; and serves as a reservoir for the bile.

All the mammalia, which want it, except the
porpoise, are vegetable eaters: and most reptiles,
which universally possess it, live on animal food,
Léçons d’Anat. Comp. tom. 4. p. 37.

The valvular transver sefolds of the cystic duct
belong only to the simiae, besides the human sub-
ject.

(B) The liver of birds is divided into two
equal lobes. The hepatic duct opens separate-
ly from the cystic; and its termination is gene-
rally, but not always preceded by one or more
pancreatic ducts, and followed by that of the
cystic duct.

The fundus of the gall-bladder receives branches
[Seite 197] from the hepatic duct, (ductus hepaticystici); but
that tube sometimes unites with the cystic, as in
the duck.

(C) The spleen gradually diminishes in size
from the mammalia to fishes. In the porpoise
there are several small spleens; supplied from
the arteries of the first stomach. It is always
attached to the first, when there are several
stomachs.

In birds it is always near the bulbus glandulo-
sus; but does not lie constantly very close to
the stomach in reptiles; as it is found in the
mesentery of the frog. Neither is it very uniform-
ly situated in fishes.

(D) The blind processes, which are attached to
the alimentary canal of insects, are supposed by
many to form a substitute for the liver. They
generally contain a yellow bitter fluid. Their
number and situation vary. They terminate for
the most part near the stomach, but not con-
stantly so. They are short and numerous in the
dragon fly, and open near the anus. In the mole-
cricket (gryllus gryllotalpa), they form a bundle,
and have a common opening in the middle of the
intestine.

In the crustacea the liver is large, and consists
of blind tubes, opening into the commencement
[Seite 198] of the intestine. It forms the soft high flavoured
substance of the crab and lobster.

(E) A liver exists in all the mollusca, and is
very large; but this class has no gall-bladder.
The liver is supplied with blood from the aorta,
and there is consequently no vena portarum.

It is a completely mistaken notion, that the
black fluid of the cuttle fish is its bile. The ink-
bag
is indeed found between the two lobes of the
liver in the sepia octopus: and in front of them in
the calmar; but in the common cuttle-fish (sepia
officinalis
), it is at a considerable distance from
this organ.

The real bile is poured, as usual, into the alimen-
tary canal.

In the gasteropodous mollusca, as the snail, the
liver is very large, and consists of several lobes,
having each an excretory duct. They surround
the stomach and intestine, and open by several
mouths into its cavity. The aplysia, onchidium,
doris,
&c. have a similar structure.

In the acephalous division of this class, it sur-
rounds the stomach, and pours its secreted liquor
into that cavity by many openings, the oyster and
muscle exemplify this.

The proper worms (vermes of Cuvier); the
echinodermata and zoophytes have nothing analogous
to this gland.

[Seite 199]

(F) The author has entirely omitted speaking
on the pancreas in this part of his work; proba-
bly because there are no remarks of any importance
or interest to be made on the subject. The struc-
ture of this gland in the mammalia, in birds, and
in reptiles is the same, on the whole, as in the
human subject: its form and size, its colour and
consistence, and its division into lobules exhibit
some slight and unimportant variations.

The termination of its duct or ducts, is distinct
in birds from that of the d. choledochus. In the
mammalia they generally open together, or there is
a branch terminating in the d. cheoldochus, and ano-
ther opening into the intestine, as in the dog and
elephant, or they may be quite distinct, as in the
hare, porcupine, and marmot. They may be sepa-
rate or distinct in different individuals of the same
species, as in the monkeys.

The skate and shark have a pancreas similar to
to that of the three first classes of red-blooded
animals. In other fishes the situation of this
organ is occupied by the caecal appendices or pyloric
caeca;
which afford a copious secretion, analogous,
no doubt, to the pancreatic liquor. (These are
mentioned in § 118.) The internal surface of
these tubes becomes very red on injection, and
possesses a glandular and secreting appearance.

The appendices, which form separate tubes in
most fishes, are collected in the sturgeon into one
[Seite 200] mass, which is surrounded by muscular fibres.
In this body, which has a very manifest glandular
structure, the tubes join together, and open into
the intestines by three large orifices.

CHAPTER IX.
ON THE URINARY ORGANS.

[Seite 201]

§ 128. These emunctory organs do not exist
in several animals, which have a biliary apparatus.
They are confined to the red-blooded classes; all
of which have kidneys, while some orders and genera
have not an urinary bladder.

(A) Mammalia.

§ 129. In some animals of this class, as the
bears1, the kidney resembles a bunch of grapes, be-
ing composed of several2 small and distinct portions,
which are connected by means of their blood-
vessels and ureters, with the common trunks of
those vessels. The urinary bladder is more loose3
in the abdomen of most quadrupeds, than in the
human subject. It is comparatively much smaller
in carnivorous than in herbivorous animals; and
[Seite 202] is particularly large in the ruminating bisulca and
the hare4. (See note (A) at the end of the
chapter.)

(B) Birds.

§ 130. The kidneys5 of this class (with a few
exceptions, as the cormorant, &c.) form a double
row of distinct but connected glandular bodies6,
placed on both sides of the lumbar vertebrae, in
cavities of the ossa innominata. The urinary
bladder is wanting in the whole class; and the
ureters open into the cloaca.

(C.) Amphibia.

§ 131. Animals of the genus testudo and rana
have an urinary bladder; which is double in many
[Seite 203] of the frogs properly so called. The crocodile
on the contrary, and several true lizards have none.
The same remark applies to the serpents, in whom
the ureters open into the cloaca. See note (B).

(D) Fishes.

§ 132. The glandulae suprarenales are wanting
in this class; and they seem therefore to be con-
fined to such animals as breath with lungs. Al-
though we cannot perceive of what use an urinary
bladder can be to fishes, and animals which live
in water, several genera and species have one.


Additional Notes to the Ninth Chapter.

(A) The structure of the kidney in mammalia
displays two very opposite varieties; which may be
called the simple and the conglomerated kidneys.
In the former there is a single papilla, which is sur-
rounded by an exterior crust of the cortical sub-
stance. This is the case in all the ferae; and in
some other animals, as many rodentia. The other
kind of kidney consists of an aggregation of small
kidneys, connected by cellular substance. It appears
that this form of the gland is found in all those
[Seite 204] mammalia, which either live in, or frequent the
water. I have observed it in the seal and porpoise,
where the small kidneys are extremely numerous,
and send branches to the ureter without forming a
pelvis. Mr. Hunter dates that it belongs to all
the whales. (Philos. Trans. 1807. pt. 2). The
otter has the same structure; but its small kidneys
are not so numerous as in the animals above-
mentioned. (Home, of the sea-otter. (Lutra
marina). Philos. Trans.
1796. pt. 2.) It is re-
markable that the brown bear (ursus arctos) which
lives on land, should have this structure as well as
the white polar bear (ursus maritimus), which
inhabiting the coasts, and floating ice of the northern
regions, spends much of its time in the water.
Mr. Hunter (loco citato) concludes, that it is
because Nature wishes to preserve an uniformity in
the structure of similar animals. But the badger,
(ursus meles), which is a very similar animal, has
the uni-lobular kidney. The number of small
kidneys in the bear is 50 or 60: and it appears
that each consists of two papillae. (See the account
of the dissection of a bear, by the French Acade-
micians: which is also given in Blasius’s Col-
lection. Anatom. Animal. tab. 32. fig. 2, 3, 4.)

(B) The two large bags, which the author, and
also Cuvier, (Leçons d’Anat. Comp. tom. 5. p.
237.) represent as urinary bladders of the frog and
toad, are stated by Townson to have no con-
[Seite 205] nection with the ureter. Indeed it is very clear
that the ureters open at the posterior part of the
rectum, while these two receptacles terminate on
the front of that intestine. (See his Tracts and
Observations,
p. 66. tab. 3.) He states that the
fluid contained in these reservoirs is a pure water.
The size of these bags, which exceeds all ordinary
proportion to the bulk of the kidney, renders it
likewise probable that they are not receptacles of
urine. Either of the bags is at least twenty or
thirty times as large as the kidney.

CHAPTER X.
ON THE EXTERNAL INTEGUMENTS.

[Seite 206]

§ 133 Among the various objects and func-
tions of the common integuments, as they are called,
one of the most important, and most general, in
red blooded animals, is the office which they per-
form as emunctory organs. Hence we may intro-
duce here with propriety what we have to say on
the subject.

§ 134. The basis of all the other coverings
consists in the proper skin (cutis vera), which is
common to the four classes of red-blooded animals,
and may be regarded as the condensed external
surface of the cellular substance, with nerves,
blood-vessels, and absorbents interwoven in its tex-
ture. This is covered externally by the cuticle,
which is very uniform in its structure, at least in such
animals as breathe by means of lungs. (See note
(A) at the end of the chapter.) The rete mucosum
lies between these; but it can only be shewn, as a
distinct layer of the skin in warm-blooded animals.
(See note (B.) Lastly, the cuticle is furnished in
the different classes with peculiar organs for the
formation and excretion of particular matters;
viz. hairs in mammalia, feathers in birds.

(A) Mammalia.

[Seite 207]

§ 135. The cutis of this class varies infinitely in
thickness. It is extremely thin and delicate in the
wing of the bat, and on the contrary, monstrously
thick in the rhinoceros, elephant, &c. also in the web-
footed animals, particularly the walrus.1 The form
of the papillae on its external surface is very various
in the different animals of this class, as, indeed, in
different parts of the same animal. They are some-
times threadlike, as on the paws of the bear, and
are very elegant on the teats of the true whale2
(baloena mysticetus). See note (C.)

The colour of the rete mucosum varies, even in
individuals of the same species, as in the different
races of mankind. It is thickest in some cetacea.3

In some spotted domestic animals, particularly
[Seite 208] the sheep, rabbit, and dog, there is a remarkable
connexion between the colour of the palate, and
even, sometimes of the iris, and that of the skin;
for spots of similar descriptions are found in both
parts.4

The cuticle is often of very unequal thickness in
particular parts, from the different purposes to which
it is destined. Thus, it is very thin on the points
of the fingers in apes and baboons, when compared
with its great thickness where it covers the callo-
sities on which they sit. In some thick skinned
animals, particularly the elephant, it forms a kind
of horny processes,5 lying close together in several
parts of the body. But differences of this kind are
too numerous to admit of their being all noticed in
this work.

§ 136. Hairs, at least single ones, are found in
all adult mammalia, even without excepting the ce-
tacea. In various states of thickness and strength,
they constitute every intermediate substance, from
[Seite 209] the finest wool to the strongest quills of the por-
cupine. Thick bristles, and hairs, as they are
found, for instance, in the tail of the elephant, and
other animals, resemble horn, or fish bones in tex-
ture; while on the other hand, both these sub-
stances may be easily split into a kind of bristles.
Hairs are commonly cylindrical; some, however,
are broad with two sharp edges; as in the toes of
the ornithorhynchus, and the common porcupine.
Others, as the whiskers of the seal,6 are also flat,
but have rounded and denticulated margins, so that
they have a kind of knotty, or jointed appearance.
Something similar may be observed in the hair of
some cloven hoofed7 animals, and most remarkably
in that which covers the scent-bag of the musk
(moschus moschiferus). These are at the same time
filled with a very loose medullary texture, and con-
sequently very brittle. Some are thick and firm,
but perforated by a narrow tube, which runs
through their axis, as the long stiff whiskers of the
[Seite 210] phoca ursina. The hairs on the tail of some species
of porcupine are entirely hollow, like the quill of
a feather.

The hair is the most incorruptible part of the
body, and possesses in great perfection, both kinds of
reproductive power; viz. the natural*, which takes
place in a healthy state, and the extraordinary,
which is exerted after an accidental loss.8 It is
electrical in some species, and serves in those ani-
mals which possess much of it, as a mode of ex-
creting superfluous phosphoric acid.9

There are secretions from the integuments in
some species of mammalia, manifesting themselves
by peculiar smells, which constitute specific charac-
ters in some of the horse and dog-kind, as com-
pletely as the national smell of certain varieties of
the human race.10

(B) Birds.

§ 137. The integuments of birds have the
[Seite 211] same three parts with those of mammalia. Some
are furnished with hair in particular situations; as
the vultur barbatus, the raven, and the turkey.
Others, as the cassowary, have long spines like fish
bones in their wings, which approach in the tubular
structure of their roots, to the formation of feathers;
the universal and peculiar covering of this class of
animals. The particular differences in the forma-
tion of the feathers are innumerable. Among the
most remarkable, are the small scale-like feathers of
the penguin’s wing; and the horny, flat, and pointed
processes on the tip of the neck, and wing-feathers
of the common fowl in its wild state; and on those
of the Bohemian chatterer, (ampelis garrulus.)
Several birds in different orders, have two or more
feathers arising from a common quill.11

The periodical renewing of the feathery cover-
ing, at what is called the moulting season, takes
place in a short space of time, and comes therefore
more under our observation, than the change of
the hair in mammalia. This process has afforded
a very interesting physiological remark, which has
been often made in several species of those birds, in
which the male and female have different plumage;
[Seite 212] viz. that as the latter ceases in her old age to lay
eggs, she obtains the male plumage.

Lastly, the integuments of birds serve the office of
emunctory organs, which is proved even by the pro-
cess of moulting, as well as by the separation of
peculiar matters from the skin. Thus the cockatoo
(Psittacus cristatus), as well as some other species of
Psittaci, and several birds of different orders, have a
large quantity of white mealy dust discharged from
their skin, particularly at the pairing time.

(C) Amphibia.

§ 138. The very various integuments, which
are found in the different orders and genera of
this class, consisting of shields, rings, scales or sim-
ple skin, are covered externally with cuticle, which
is frequently separated in many of these animals, as
in the snake, (forming what is called in German,
Natterhemd, i.e. snakes-shirt) and water-newt.

This process of separation is repeated every week
for some time in the latter animal, particularly
in spring and autumn. Some which have small
fine scales, as the chameleon, or a simple skin, as
some frogs change their colour occasionally, either
from difference in the light or warmth, or from the
effect of their passions. (For a peculiarity in the
skin of the toad, see note (D).

(D) Fishes.

[Seite 213]

§ 139. All fishes, without exception, are co-
vered with scales, which are bare in those which
inhabit the open sea, but on the contrary are covered
with a mucous membrane in those which live on
coasts, or in fresh water. It is remarkable, that the
colour of the skin in some fishes, as for instance,
the mullet, (mullus barbatus) depends on that of
the liver.12 The scales are not changed like hair
and feathers, but are perennial; and are said to
receive yearly, an additional layer to their laminated
texture, from the number of which the age of the
animal may consequently be determined. (For
some account of the epidermis in the lower orders
see note E. and of the various insensible coverings
note (F).


Additional Notes to the Tenth Chapter.

(A) The epidermis of the cetacea is quite smooth;
and marked with none of those lines, which are so
often seen in the other mammalia.

[Seite 214]

It is detached from the surface, in the form of
small scales, in all the mammalia, except the whales.
And in some this happens chiefly at the season when
their hair is shed. It gives the skin a brauny ap-
pearance.

(B) It is in the rete mucosum that the colour
of the skin resides; but this part possesses in very
few instances, any brilliancy of colour in the mam-
malia. It is of a beautiful red and violet on the
nose and buttocks of some baboons: and silvery
white on the abdomen of the cetacea. It is re-
markably thick on these animals; being about the
sixteenth of an inch on the back, and such parts
as are of a black colour.

(C) Villi, or papillae of the skin are found on
those parts which correspond to the toes and fin-
gers of man. They exist also on the trunk of the
elephant, and on the snout of the mole and pig.

The cutis of mammalia is much thicker on the
back than on the belly.

(D) The skin of the frog and toad does not
adhere to the subjacent parts, as in other animals;
but is attached to them only at a few points, and
is unconnected elsewhere: so that it may be com-
pared to a bag containing the animal.

(E) The lower orders possess in general an
epidermis. In the testacea it usually covers the sur-
[Seite 215] face of the shell, and obscures the brilliancy of that
part, until it is removed. It maybe seen by plung-
ing a snail-shell into boiling water. It is very thick
and villous in some species, as in the area pilosa.

Crustacea have it; also insects both in their
perfect and larva states. It is shed in the latter
several times before the change to the state of
chrysalis: (seven times in most of the butterflies and
bombyces).

It is very distinct in the vermes; as in the com-
mon earthworm and leech, which often shed it. In
the sipunculus saccatus it is loose and not adherent
to the surface.

(F) Hairs are formed in small bulbous bodies
implanted in the true skin, and grow from their
base.

If one of the large hairs, which grow on parti-
cular parts of some animals be examined with
glasses, its surface appears grooved, as if it were
composed of several filaments; and one or two
canals are discovered in the substance of the hair,
containing a kind of fluid, which has been called
the medulla.

In the hedgehog, porcupine, &c. these filaments
are covered with a layer of horny substance; and
the cavity is filled with a white spongy matter.

The colour of the hair is influenced in great mea-
sure by that of the rete mucosum: and this cir-
cumstance is particularly observable in the human
[Seite 216] subject. Its texture is much modified by climate
and mode of life. The dog in Siberia, and the
sheep in Iceland are covered with a kind of long
and stiff hairs, while the same animals, in very hot
countries, as in Guinea, lose this covering altoge-
ther. A species of goat furnishes the long and silky
hair, which is manufactured into the valuable shawls
of Cashmere. The cat, rabbit, and goat are covered
with a very long and peculiar kind of hair in An-
gora, a small district of Asia Minor; and the supe-
rior qualities of the Spanish wool are well known.

This seems to be the proper place for considering,
in a cursory manner, the other insensible parts,
which are found on the surface of the body.

The horns of the mammalia are generally formed
on processes of the frontal bone; which they cover
in the manner of a sheath, as a glove does the fin-
ger. They consist of a solid, insensible, and elastic
substance; which in many cases has a fibrous ap-
pearance, as if it were composed of an aggregation
of hairs. This structure is most particularly re-
markable in the rhinoceros; where the horn is solid,
and situated over the nasal bone. The fibres ana-
logous to hairs are very distinct, and are observable
at the base of the horn, detached from its substance
in the form of bristles. The mass of the horn is
entirely pervaded by innumerable pores.

In those animals which have a long process within
the horn, the os frontis begins to form a tubercle,
about the seventh month of conception. This be-
[Seite 217] ing gradually elongated, elevates the integuments,
which become callous, and harden, as the horn is
lengthened. Between the bone and the latter part
a soft vascular substance is interposed: from which
the horn is produced, by means of successive addi-
tions to its base and internal surface.

The nails and claws of animals are formed just
like horns; they cover a process of the last pha-
lanx, which is analogous to the frontal process of
the horn; and grow from the root or base, to
which the integuments are attached, while they
wear away at the loose edge.

The hoof of the horse, ass, &c. is a horny cover-
ing of the last phalanx; similar, in its structure and
formation, to the parts just mentioned, but inclu-
ding the whole of the bone. Its internal surface
in the horse is formed into a vast number of thin
plates, which are placed alternately with correspond-
ing laminae of the vascular substance, and consti-
tute a most close connection between the two parts.
This union is so firm, that, when the inferior portion
of the hoof has been removed, a horse may be
trotted roughly without the foot being separated
from the upper part of the hoof.

The body of a bird which has just quitted the
egg, is covered with hair instead of feathers. Fas-
ciculi of hairs are produced from one common
bulb, which is the rudiment of the future feather.
In a few days a black cylinder appears, which opens
at its extremity, and gives passage to the feather.
[Seite 218] The opposite end receives those blood-vessels, which
supply the vascular substance in the barrel of the
feather; when the stalk of the feather has received
its complete growth, this vascular body is dried up,
and presents the well-known appearance in the bar-
rel of quills.

The parts which have been just described, as well
as the epidermis, and the scales, or other hard co-
verings of reptiles and fishes possess neither vessels
nor nerves; and therefore the whole superficies of
an animal’s body is really insensible, and constitutes
a dead medium, through which impressions are con-
veyed to the subjacent living parts.

(G) I introduce the following quotation from
the 2d chapter of the author’s Manual of Natural
History (Handbuch der Naturgeschichte,
ed. 6,
Göttingen, 1799) because it explains the terms
made use of in the 136th paragraph; represents
the subject in an interesting point of view, and con-
tains the result of some curious experiments.

‘“In speaking of the growth of organized bodies,
we must notice their power of reproduction, – that
wonderful property, of restoring or renewing parts,
that have been mutilated or entirely lost. This is
one of the wisest provisions of nature for guarding
animals and plants against the numerous dangers,
by which they are surrounded. Hence, when view-
ed in connection with the system of growth altoge-
ther, it constitutes one of those grand characters,
[Seite 219] which distinguish the machines that proceed from
the hand of the Creator, from all the productions
of human skill. The springs and wheels of me-
chanical instruments have no power of repairing
themselves when injured or worn; but such a
power, in different degrees is imparted to every ani-
mal and plant.’

‘At different periods of the year, several organized
beings lose by a spontaneous and natural process
certain parts of their body, which are subsequently
renewed. Examples of this occur in the fall of the
Stag’s horns; in the moulting of birds; in the re-
newal of the cuticle of serpents, and of the larvae of
insects, and that of the shell of the crustacea; the
fall of the leaves of trees, &c. This may be called
ordinary or natural reproduction.’

‘The second, or extraordinary kind of reproduc-
tive power is that, by which wounds, fractures, or
any accidental mutilation or loss of parts of an or-
ganized body, are remedied or restored. Man in-
deed, and such animals as are nearly allied to him,
possess this property in a very limited degree, while
its strength and perfection are truly astonishing in
several cold-blooded animals, as the water-newt, the
crab and lobster, snails, earth-worms, (lumbricus
terrestris,) sea-anemones, (actinia), the starfish,
(asterias,) fresh-water polipes (hydra), &c.’

‘Some experiments on this reproductive power
require a hand exercised in such employments, to-
gether with various precautions, and a favourable
[Seite 220] combination of circumstances, for their success.
Hence persons must be cautious in concluding
against the truth of any statement, because their own
experiments do not succeed. After several fruit-
less attempts on this subject, I have lately succeeded
in observing the reproduction of the whole head of
the snail (helix pomatia) with its four horns;
which occupied about six months.’

‘I preserve in spirits a large water-newt (lacerta
palustris
), from which I extirpated nearly the whole
eye several years ago. All the humours were dis-
charged, and then four-fifths of the emptied coats
were cut away. In the course of ten months an
entirely new eye-ball was formed; with cornea,
iris, crystalline lens, &c.; and this is only distinguish-
ed from the same organ on the opposite side, by
being smaller.”’ (See the Gottingen Literary Notices
for 1787) p. 28, 30.

CHAPTER XI.
ON SEVERAL PECULIAR SECRETIONS.

[Seite 221]

§ 140. It is necessary that we should take no-
tice of some organs, destined for the secretion of
peculiar fluids, the use of which is not hitherto
sufficiently determined. These occur in particular
classes, or in certain genera and species of animals;
and may be most conveniently considered here, at
the end of that division, which treats of the na-
tural functions.

(A) Mammalia.

§ 141. Besides the well-known salivary glands,
there is another, which has been described by
Nuck in the orbit, particularly of the dog, and
some other predacious animals, which has an excre-
tory duct opening near the last tooth of the upper
jaw1.

§ 142. Both sexes of both species of the ele-
phant,
viz. the African and Indian, have a consider-
[Seite 222] able gland2 at the temple, between the eye and
meatus auditorius, secreting in the rutting season a
brownish juice, which is discharged through an
opening in the skin3.

As far as regards the structure of the organ, this
secretion resembles most, that of the gland placed
at the back of the Mexican musk hog or pecare
(sus tajaçu). (See note (A), at the end of the
chapter).

§ 143. Several ruminating bisulca, and the
hare, have, in the part which has been noticed above
(§ 16.), sebaceous sinuses, which have received that
name from the adipous and viscous substance,
which is separated there in great abundance in some
animals, and which is well known in the stag,
where it is supposed to be of a lacrymal nature4.

§ 144. In most of the ruminating animals, and
[Seite 223] in the hare, there are cavities in the groins, near
the genitals, called by Pallas antra inguinatia; and
containing a strong-scented sebaceous substance se-
creted from glands which lie under the integu-
ments5.

§ 145. Some other mammalia have pouches
on the abdomen, covered internally with a fine
hair, and containing fatty secretions of peculiar
odours. Of this kind are the bags near the anus
the badger; and that which contains the teats
the female marsupial animals6.

§ 146. There are also in the badger, and the opos-
sums,
as well as in several other carnivorous animals,
(both among those, which are furnished with sepa-
rate toes (digitata), and those which are web-
footed (palmata) peculiar glands and bags at the
end of the rectum, secreting a yellow substance of
a strong and disagreeable smell in its recent state,
and which frequently gives to their excrement a
kind of musk-like odour7. (See note (B).

[Seite 224]

§ 147. These anal glands must be distinguished
from another kind of similar glands and bags,
which also secrete strong-scented matters, but seem
to be rather connected with the genitals8. These
are found in some of the same carnivorous animals,
which possess the anal glands, as the lion, the ci-
vette,
&c.; also in many herbivora, which want
the latter organs; in some of whom they exist in
both sexes, as in the beaver9, the ondatra10 (mus zi
bethicus
), &c. in others they are peculiar to the
male, as in the musk animal11, whose pouch is
found in the prepuce near the navel. (See
note (C).

§ 148. We must also mention here the glan-
dular cavities, covered internally with hair, which
are found in the feet of several ruminating bisulca,
and particularly in the sheep. They have an ex-
cretory duct opening at the junction of the toes12;
[Seite 225] and the obstruction of this, particularly from a long
continuation of wet weather, occasions troublesome
symptoms.

(B) Birds.

§ 149. Although birds do not masticate their
food, several of them, particularly among the pici,
have considerable salivary glands at the sides of the
lower mandible. The secretion of these glands
serves to facilitate the numerous and strong mo-
tions performed by the tongue in deglutition.
(See note (D).

The pancreas is of considerable size particularly
in those birds of prey, which do not drink: its form
and structure vary considerably.

§ 150. The glands which secrete the oil, on
the upper part of the tail, are largest in aquatic
birds; in some of which, as the anas moschata, the
secreted substance has a musk-like odour. In that
race of the common fowl, which has no tail, (the
Gallus ecaudatus) this organ no longer exists.13
(See note (E).

(C) Amphibia.

[Seite 226]

§ 151. I do not think it probable, that the
part, which has often been considered as a pan-
creas
in this and the following classes of animals,
really deserves that name14.

Anal glands, which disseminate a strong specific
odour at certain times are found in some animals
of this class; for instance in the Cayman (Lacerta
Alligator
), and the rattlesnake15.

§ 152. An acrid fluid exudes through numer-
ous pores of the skin in some reptiles, when they are
irritated; as in the salamander and in toads. It is
said that the gecko secretes a really venomous fluid
between its toes. But there is a much more dan-
gerous kind of poison formed in some serpents,
which are distinguished from the innocent ones by
the organs pointed out in the 71st paragraph.
(See note (F).

(D) Fishes.

§ 153. The most universal secretion in this
class, which comes under the present chapter, is
[Seite 227] that of the mucus, which besmears their skin and
scales, and which is formed in canals16 lying near
the lateral lines, and in the same direction with
them; one or more of these canals running on each
side from the head to the tail-fin. In some fishes the
mucus is poured out in the intervals of the scales;
but in others those parts are perforated by regular
openings for its discharge17. (See note (G).

(E) Insects.

There are no true conglomerate glands, nor ana-
logous parts in insects; but their different secre-
tions are performed by loose vessels18. Besides
the different secretions of peculiar matters, which
belong exclusively to single species, as the vapour,
which some carabi (carabus crepitans, marginatus,
&c.) discharge, and the strong odours with which
several of the bug-kind defend themselves in case
of necessity, two kinds of secreted fluids deserve
to be particularly remarked in this class: the silk
[Seite 228] which is formed by the larvae of phalenae19 (moths)
and by spiders20; see note (H) and the poison with
which several hymenopterous1 and apterous2 in-
sects are armed. See note (I).

The wax, which is prepared by the honey-bees,
and by the Indian coccus mellificus, deserves to be
enumerated among the secretions, which are pecu-
liar to animals of this class.

(F) Vermes.

§ 155. The most remarkable secretions in this
class take place in the testacea. There is one of
these common to the whole class; viz. the for-
mation of the calcareous matter of their shells3,
which takes place in a peculiar viscus lying near
the heart (sacculus calcarius Swammerd. glan-
dula testacea
Poli.) The celebrated purple4
colour is formed in some marine genera; as the
[Seite 229] Buccinum lapillus and echinophorum, murex brandaris
and trunculus, Helix ianthina, arca nucleus, &c.
Lastly some bivalves, under extraordinary circum-
stances form pearls5 on the inner surface of their
shell. (See note (K) for an account of the silk,
secreted by mollusca, and note (L) for the ink of
the cuttle fish.)


Additions to Chapter the Eleventh.

(A) This remarkable gland is found on the
back of the animal, over the sacrum. It is of a
considerable size (between two and three inches
long, and above and inch broad), and is composed
of several lobules, whose ducts join into one canal,
which penetrates the skin. It furnishes a secretion
of a very pleasant musk-like odour, from which
Tyson denominated the animal aper moschiferus.
The opening of this part on the back has been
described by many authors as the navel (Bar-
tholin.
Cent. 2. Hist. Med. 96.)

Tyson in the Philos. Trans. No. 153, or in
his works, London, 4to. 1751, with a good delinea-
tion of the gland.

[Seite 230]

(B) These anal bags are of a spherical form,
and have a small round opening just at the margin
of the anus. They seem to belong particularly to
the carnivorous animals. They may be seen very
well in the cat. Their secretion possesses that
strong disagreable odour, which characterises so
remarkably many animals of this order, as the fox
and all the weazel tribe; and which has even made
the polecat proverbial in common language, and
has bestowed on it its scientific name, mustela pu-
torius.
Some American species exceed the fetor even
of the polecat. This is the case with the viverra
mephitica
and coasse (the skunk and squash). They
pour out the fetid matter when pursued; and are
thereby effectually defended, as neither man nor
animal can approach them.

These parts are not however confined to the
carnivora, as several rodentia possess them.

(C) It is from these glands, and not from the testi-
cles, as naturalists have absurdly supposed, that
the substance called castoreum is produced. A de-
lineation of the parts, from the dissection of the
Parisian academicians, may be seen in the collection
of Blasius. Anatom. Animalium. tab. 13.

That valuable article of the materia medica,
musk, is produced from similar glands in the mos-
chus moschifer
(in English the musk), an animal
[Seite 231] found in the mountains of Thibet, and the fouthern
parts of Siberia.

(D) I have already stated that salivary glands,
in the proper sense of the term, do not exist in
birds; and that the parts which the author men-
tions here, must be regarded in a different point of
view. (See the note to § 94.)

(E) Tyson states that the ostrich has this gland
situated not on the rump, but further forwards,
(Anatomy of the Mexican Musk-hog, p. 39.) I have
observed in the situation, which he mentions, a
pretty considerable bag with hard callous sides,
and nothing glandular in its coats. It contained
a brown and unctuous, but nearly solid matter, and
I could discover no external opening; but it had
been somewhat cut before I examined it. It cannot
I think be very well compared with the oil bag of
the rump.

(F) There is found in the crocodile, on each
side of the lower jaw, and just under the skin, a
gland, whose duct opens externally. It secretes a
substance smelling like musk.

(G) Cuvier represents the tubes which open
in the course of the linea lateralis of fishes, as the
excretory ducts of two glands placed above the
orbits. (Léçons d’Anat. compareé.) tom. 5.
p. 260.

[Seite 232]

In the skate the openings are not confined
to any particular part, but are scattered over
the surface. The tubes radiate from one point,
just above the angle of the jaw; and the third
branch of the fifth pair of nerves is distributed
at that part; its filaments accompanying the
tubes.

For an account of the electrical organs of fishes,
which must be considered as parts secreting the
electrical matter, see § 217: and for their swim-
ming bladder, in which a secretion of air is ef-
fected, § 186.

(H) Almost all the larvae or caterpillars spin
for themselves some kind of covering before their
metamorphosis; but it is the silkworm only (bom-
byx mori
), that furnishes the materials of our
various silk manufactures, as the thread which it
forms is very pliant and abundant, and can be
easily unrolled.

The secretory organs, which furnish this matter
of silk, are the same in all larvae. They consist
of two long tubes, at first small and tortuous, but
growing gradually larger to form a kind of reser-
voir, and terminating in a single very small tube,
which opens under the lower lip. It is by moving
its head from side to side, that the animal draws
out the silk.

(I) In those insects, which possess stings, the
[Seite 233] irritating or poisonous fluid is formed in a peculiar
bag, which sends a duct to the sting. The latter
part is hollow, and its tube opens externally. It
is contained in a sheath, and barbed at the sides of
its point, so that it usually remains in the wound,
which it inflicts. A delineation of these parts in
a magnified view may be seen in Swammerdam,
tab. 27. of the English translation.

(K) Several acephalous mollusca produce a
kind of silk, similar to that of the larvae of insects.
It is sometimes called the beard; and is employed
by the animal in order to attach itself to rocks, &c.
It is formed by a conglomerate gland, placed near
the foot; which latter part draws out the silk from
the excretory duct, and moulds it in a groove on its
surface. The sea muscle (mytilus) the pinna, and
perna, exemplify this structure. The pinna pro-
duces it in such quantity, and of such quality, as
to admit of its being manufactured into gloves,
which is done at Messina and Palermo (Blumenb.
hanabuch der Naturgeschichte. ed. 6. p. 438.)

(L) The black inky fluid of the cuttle-fish,
which has often been supposed to be the bile, is a
very singular secretion, that must be noticed in
this place. The bag, in which it is contained, has
a fine callous internal surface, and its excretory
duct opens near the anus. The fluid itself is thick,
but miscible with water to such a degree, that a
[Seite 234] very small quantity will colour a vast bulk of
water; and the animal employs it in this way to
elude the pursuit of its enemies. According to
Cuvier, the Indian ink (which comes from China)
is made of this fluid. (Léçons d’Anat. Comp. tom. 5.
p. 262.)

[Seite 235]

THE
VITAL FUNCTIONS.

[Seite 236]

CHAPTER XII.
ON THE HEART AND BLOOD-VESSELS.

[Seite 237]

§ 156. A perfect circulating system, to which
on the one hand fluids are brought by the absorb-
ents, to be converted into blood; and from which
on the other side, various juices are separated in
glands, and viscera of a glandular structure; ap-
pears to belong universally and exclusively to red-
blooded animals. A pericardium exists in all these
animals.1 Parts of such a system, particularly a
heart, and certain vessels connected with it are
found in some genera of the two white-blooded
classes.

(A) Mammalia.

§ 157. The internal structure of the heart is
the same as in man; but its situation in quadru-
[Seite 238] peds and cetacea differs from that which it has in
the human subject. It is in the former more
lengthwise with respect to the body; resting rather
on the sternun than on the diaphragm. Hence
the pericardium of these animals is not connected
with the diaphragm2 as in the human subject; the
portion of the inferior vena cava within the chest
is proportionably longer.3 (See note (D) at the
end of the chapter.)

§ 158. The larger adult bisulca, and the pig
have two small flat bones, (which have been called,
particularly in the stag, bones of the heart) where
the aorta arises from the left ventricle. The com-
mon notion that they serve as a support to the
valves,4 does not much elucidate the subject. (See
note (B).

§ 159. It has been supposed, that the amphi-
bious animals of this class and the cetacea have an
open foramen ovale, like that of the foetus, in their
septum auricularum. And the necessity of their
an opening has been inferred from their way of
[Seite 239] life; since they often pass a considerable time under
water without breathing. This supposition has
been fully refuted by the repeated dissection of
adult animals of this kind; which has shewn that an
exception from the general rule very rarely occurs.5
(See note (C).

In several genera and species, of web-footed mam-
malia, and cetacea (that is, in the common and sea-
otters, in the dolphin, &c.) particular vessels have
been observed to be considerably and constantly
enlarged, and tortuous. This structure has been
principally remarked in the inferior vena cava;
where there can be no doubt that it serves, while
the animal is under water, to receive a part of
the returning blood, and to retain it until respira-
tion can be again performed, and the lesser6 circu-
lation be thereby again put in action.

§ 160. There are some remarkable circum-
stances in the distribution of particular arteries in
certain animals of this class. We may notice, as
[Seite 240] the most singular of these, the rete mirabile, formed
by the internal carotid at its entrance into the cra-
nium, in several ruminating biscula7, and carnivo-
rous animals: and that division of the arterial
trunks of the extremities, which has been observed
by Mr. Carlisle8 in the flow-moving animals, viz.
the sloths, and lemur tardigradus. The arteries
of the arm and thigh in these cases, divide as they
leave the trunk into numerous parallel branches,
which are united again towards the elbow and
knee.* (See note (D).

(B) Birds.

§ 161. The whole of this class without excep-
tion, possess a very remarkable peculiarity in the
structure of the heart. The right ventricle, instead
of having a membranous valve (such as are found
in both ventricles of mammalia, and also in the left
of birds), is provided with a strong, tense, and
[Seite 241] nearly triangular muscle. This singular structure
assists in driving the blood with greater force, from
the right side of the heart into the lungs: since the
expansion of the latter organs by respiration, which
facilitates the transmission of the carbonated9 blood
in mammalia, does not take place in birds, on ac-
count of the connection which their lungs have
with the numerous air-cells, which will be after-
wards described.10

(C) Amphibia.

§ 162. The frogs, lizards, and serpents, of this
country at least, have a simple heart, consisting of
a single ventricle and auricle.11 See note (E).

§ 163. The structure of this part is very diffe-
rent in the turtle;12 and has given rise to more
controversy than that of any order of animals.
[Seite 242] Their heart possesses two auricles,13 which are sepa-
rated by a complete septum, like those of warm-
blooded animals, and receive their blood in the
same manner, as in those animals; viz. the two
venae cavae terminate in the right auricle, the pul-
monary veins in the left. Each pours its blood into
the corresponding ventricle, of which cavities there
are two: thus the structure of the heart hitherto
resembles that of mammalia.

The characteristic peculiarities, which distinguish
the heart of these animals, consist in two circum-
stances. First, both the ventricles communicate to-
gether; there is a muscular, and as it were tubular
[Seite 243] valve, going from the left to the right cavity, by
means of which the former opens into the latter.
Secondly, the large arterial trunks arise all toge-
ther from the right ventricle only (no vessel coming
from the left). The aorta, forming three grand
trunks14, is situated towards the right side and the
upper part; the pulmonary artery comes as it were
from a particular dilatation15, which is not situated in
the middle of the basis of the heart, but lower; (it
must be understood, as we have already observed,
that we apply these terms according to the hori-
zontal position of the animal.)

We can now comprehend how this wonderful
and anomalous structure, by which all the blood is
propelled from the right ventricle only, is accom-
modated to the peculiar way of life of the animal,
which subjects it frequently to remaining for a long
time under water. For the greater circulation is
so far independent of that, which goes through the
lungs, that it can proceed, while the animal is un-
der water, and thereby prevented from respiring,
[Seite 244] although the latter is impeded. In warm-blooded
animals, on the contrary, no blood can enter the
aorta, which has not previously passed through the
lungs, into the left ventricle; and hence an obstruc-
tion of respiration most immediately influences the
greater circulation16.

(D) Fishes.

§ 164. The heart in this class of animals is ex-
tremely small in proportion to the body. Its struc-
ture is very simple, as it consists of a single auricle
and ventricle, which correspond with the right side
of the heart in warm-blooded animals. The ven-
tricle gives rise to a single arterial trunk (which is
expanded in most fishes into a kind of bulb as
leaves the heart), going straight forwards to the
branchiae, or organs of respiration. The blood
passes from these into a large artery, analogous to
the aorta, which goes along the spine and supplies
[Seite 245] the body of the animal. It is then returned by the
venae cavae into the auricle17.

§ 165. Most cold-blooded animals, as fishes, and
the amphibia of this country, have a much smaller
proportion of blood, and fewer blood-vessels than
those with warm blood. On the contrary, they
have a much greater number of colourless vessels
arising from the arterial system.18

(E) Insects.

§ 166. A true heart, and system of vessels con-
nected with it, are found in a very few of what
are called white-blooded animals. In this class
they seem to belong only to some genera of insects
[Seite 246] which have no wings; as the genus cancer,19 and
monoculus. Several of the older zootomists consi-
dered the dorsal vessel of the larvae, &c. to be a
heart; but this opinion has been already refuted by
Lyonet. In the genera which we have mentioned,
there seems to be no passage of the arterial extre-
mities into the origins of veins, and consequently no
true circulation. (On the mode of nutrition in
these animals, see note (F).

(F) Vermes.

§ 167. In many genera of this class, particularly
among the mollusca20 and testacea,1 there is a very
manifest heart2, which is sometimes of a singular
structure. It consists, for instance, in the cuttle-fish,
of one ventricle, and two auricles, which lie at
some distance from the ventricle, near the gills.
[Seite 247] Some bivalves are said by Poli to have two auricles,
and some even four. But in all these instances,
there has been no connection hitherto discovered
between the arteries and veins;3 while on the other
hand some genera in other orders of this class
have a connected system of vessels without a heart;4
and the proper zoophytes cannot be said to possess ei-
ther; as their nutrition seems to be effected by an
immediate derivation of the nutritive fluid from
their abdominal cavity into the gelatinous paren-
chyma of their body5.*

Additional Notes to the Twelfth Chapter.

[Seite 248]

(A) The heart of the orang outang is placed
obliquely like that of the human subject; but in
other simiae the apex only is a little inclined to the
left, and just touches the diaphragm.

(B) The right auricle receives in the porcupine
and elephant two anterior venae cavae; the left of
which opens near the communication with the
ventricle.

(C) The question, whether or no the foramen
ovale
be open in such animals, as have the power
of diving, and remaining for some time under water,
seems to be as yet not completely decided. In
addition to the affirmation of the author, § 159,
the evidence of Cuvier may be quoted; he states
that in several porpoises, in a dolphin, and a seal, he
found this opening closed. (Léçons d’Anat, Comp.
tom.
4. p. 201) The Parisian dissectors also found
it closed in a beaver. (Description Anatom. d’un
castor.
&c.p. 68.) It was perfectly shut in a por-
poise
and young seal which I examined: and ac-
cording to Mr. Home, (Philos. Trans. 1802) it is
closed in the ornithorhynchus. On the other side of
the question, besides the fact mentioned in note 5,
which is very striking, we may adduce Mr. Home’s
authority for the existence of the foramen ovale, in
[Seite 249] an open state, in the sea otter. He found it so in
two instances; one of which was in an adult ani-
mal. But the ductus arteriosus was closed. (Philos.
Trans.
1796, pt. 2). This may perhaps be nothing
more than a casual occurrence; as a small opening
is not unfrequent in the human subject; and I
lately met with the communication as free as in the
fetal state, in a person, who had no symptom of
disease, or defect in the circulating system during
life.

(D) Plexuses or convolutions of the arteries
are found in some parts of the cetacea; as in the
intercostal arteries, in the branches which go from
the subclavian to the chest, in those which supply
the medulla spinalis, and the eye. Hunter in the
Philos. Trans. 1789, pt. 2.

(E) The account which Cuvier gives of the
anatomy of the heart in the amphibia, does not ex-
actly accord with that of the author. Cuvier de-
scribes and delineates the heart of the crocodile as
being formed nearly like that of the turtle (tom. 5.
pl. 45); he says that the iguana has a similar struc-
ture, and that it obtains likewise in the serpents,
(tom. 5. p. 221–225.) He does not mention the more
simple form as existing in any lizard or serpent.

(F) It appears that insects possess neither blood-
vessels, nor absorbents. Cuvier has examined, by
means of the microscope, all those organs in this
[Seite 250] class, which in red-blooded animals are most vas-
cular without discovering the least appearance of a
blood-vessel; although extremely minute ramifica-
tions of the tracheae are obvious in every part. And
Lyonet has traced and delineated in the cater-
pillar, parts infinitely smaller than the chief blood-
vessels must be, if any such existed. Anatomie de
la Chenille,
&c.

Yet insects, both in their perfect, and in their
larva state, have a membranous tube running along
the back, in which alternate dilitations and contrac-
tions may be discerned. From this circumstance
it has been supposed to be the heart: but it is closed
at both ends, and no vessels can be perceived to ori-
ginate from it.

It is obvious from these data, that the functions
of nutrition and secretion must be performed, in
the animals which we are now considering, in a
very different manner from that which obtains in
the more perfect classes. Cuvier expresses the
mode, in which he supposes growth and nutrition
to be effected, by the term ‘“imbibition.”’ And he
explains from this circumstance, the peculiar kind
kind of respiration, which insects enjoy. Since the
nutritive fluids have not been exposed to the
atmosphere, before they arrive at the parts for
whose nourishment they are destined; this exposure
is effected in the parts themselves, by means of the
air-vessels, which ramify most minutely over the
whole body. ‘“En un mot, le sang ne pouvant
[Seite 251] aller chercher l’air, c’est l’air, qui va chercher le
fang.”’ (Léçons d’Anat. Comp. 1. 23, sect. 2, art. 5).

The heart of the crustacea according to Cuvier
has no auricle; and it is what he calls an aortic
heart.
For it expels the blood into the arteries of
the body; and this fluid passes through the gills
previously to its reaching the heart again. The
different parts of the system are here found under
a mode of connection exactly the reverse of what
we observe in fishes; where the blood is sent into
the gills, and passes subsequently into the aorta.
The circulating organ in that class is therefore a
pulmonary heart.

I do not comprehend what the author means by
stating, that there is no communication between the
arteries and veins in the crustacea. If the blood is
sent out in the one system of vessels, and returns by
the other; does not this prove the communication?

(G) According to Cuvier, the cuttle-fish has
three hearts, neither of which possesses an auricle.
Two of these organs are placed at the root of the
two branchiae: they receive the blood from the
body, (the vena cava dividing into two branches,
one for each lateral heart) and propel it into the
branchiae. The returning veins open into the mid-
dle heart; from which the aorta proceeds.

The other mollusca have a simple heart, consist-
ing of one auricle and ventricle. The vena cava
assumes the office of an artery, and carries the re-
[Seite 252] turning blood to the gills; whence it passes to the
auricle; and is subsequently expelled into the aorta.
Here therefore, as in the crustacea, the heart is a
pulmonary one.

The vermes of Cuvier have circulating vessels,
in which contraction and dilatation are perceptible;
without any heart. They can be seen very plainly in
the lumbricus marinus. The leech, naias, nereis, aphro-
dite,
&c. are further examples of the same struc-
ture. This anatomist is of opinion that the mol-
lusca, crustacea,
and vermes, possess no absorbing
vessels; and he thinks that the veins absorb, as he
finds them to have communication with the general
cavity of the body, particularly in the cuttle-fish.
Hence the above mentioned classes will hold an in-
termediate rank, between the vertebral animals,
which possess both blood-vessels, and absorbents;
and the insects which have neither. (Léçons, &c.
1. 23. sect. 2. art. 4).

CHAPTER XIII.
OF THE ABSORBING VESSELS.

[Seite 253]

§ 168. It was regarded as an axiom even by
Valsalva, that those animals, which have true
blood-vessels, have also an absorbing or lymphatic
system. It appears also that the converse of this
proportion is true: viz. that those classes only
have true lymphatic vessels, which possess at the
same time a perfect circulating system of blood-
vessels; that is, only the four classes of red-blood-
ed animals.

In many of what are called white-blooded ani-
mals, there is a kind of absorption very evident;
as in the armed polypes, whose parenchyma be-
comes tinged in a short time with the colour of
those insects, which have been swallowed. The
existence of absorption is inferred by analogy from
other phoenomena, as the metamorphosis of larvae,
&c. But no true system of real absorbing ves-
sels has been hitherto demonstrated in these
animals1.

[Seite 254]

§ 169. This system (which comes most properly
under consideration in the present chapter, on ac-
count of its relation to the circulation of the blood),
consists of the lacteal vessels, which arise from the
small intestines, and of the proper lymphatic vessels,
which belong to the rest of the body. It includes
also the conglobate glands, which are found in most
of the animals, which have this system, and seem
to consist merely of a congeries of the vessels; and
lastly, the thoracic duct, which is the chief canal for
conveying the fluids from the lymphatic system into
the blood. (See note (A) at the end of the chap-
ter.)

(A) Mammalia.

§ 170. All the parts of the absorbing system,
which have been just enumerated, are most perfect
and manifest in this class of animals2. When their
lacteals contain chyle, they are distinguished by their
white colour from the other absorbing vessels, the
contents of which are either limpid, or of a flight
yellow tinge. The former vessels run together in
considerable trunks, particularly in the sheep and
goat: the latter, or true lymphatics, may be seen
[Seite 255] to advantage on the hind-leg of the horse, where
they follow a tortuous course.

The thoracie duct is double in some quadrupeds3,
as in the dog, and forms at its commencement,
more constantly than in the human subject, a ve-
sicular enlargement, called the cisterna or recepta-
culum
4 chyli. (See note (B).

In many mammalia, particularly of the order
ferae, the mesenteric glands are collected into one
mass, which is known by the inappropriate name of
Pancreas Asellii5.

(B) Birds.

§ 171. The chyle is transparent in this class;
therefore the lacteals are only distinguished from
the lymphatics by their situation and office. There
are no glands in the mesentery, although conglo-
[Seite 256] bate glands are found in other parts in several of
the larger birds. Their thoracie duct is doubles6.

(C) Amphibia.

§ 172. Lacteals are found in great number in
the delicate mesentery of the turtle. The thoracie
duct is double. There seem to be no lymphatic
glands at all7. (See note (C).

(D) Fishes.

§ 173. The lymphatics of these animals seem
to be destitute of glands and valves: they want
also the lymphatic glands, and their thoracic duct
divides at least towards its anterior part, into two
chief branches8.


Additional Notes to the Thirteenth Chapter.

The structure and offices of the absorbent glands
have been illustrated by the observations of Mr.
Abernethy on the formation of these parts in
the whale. He found the mesenteric glands of that
[Seite 257] animal to consist of large spherical bags, into which
several of the lacteals opened. Numerous vessels
ramified on these cysts; and the injection passed
from their secerning extremities into the cavity.
In the groin and axilla of the horse he also
found them to consist of one or more cells. Hence
there can be no doubt that the absorbed fluid must
receive an addition in its passage through these
bodies. Philos. Trans. 1796. pt. 1.

It has been much questioned, whether the lym-
phatics have any communication with the venous
system, prior to the termination of the thoracic
duct. The observations of that ingenious veteri-
nary surgeon, Mr. Bracy Clark, have determined
this question in the affirmative; as he has found
the trunk of the lymphatic system to have several
openings into the lumbar veins in the horse. Rees’s
Cyclopaedia, article Anatomy Veterinary.

(B) Mr. Home has found that in the sea-otter
the receptaculum chyli sends two trunks to form
the thoracic duct. These have frequent commu-
nications; so that there are sometimes three, fre-
quently four, and never fewer than two trunks run-
ning parallel to each other. Philos. Trans. 1796,
pt. 2.

(C) The distribution of the lymphatics on the
intestine of the turtle forms one of the most elegant
preparations in comparative anatomy. By fixing
[Seite 258] the injecting tube in a vessel near the intestine,
and waiting with a little patience, the quicksilver
will gradually find its way into the minute ramifi-
cations of the lacteals. The peritoneal surface of
the gut is covered with very minute straight parallel
branches, running according to the length of the
intestine. Its inner surface is no less thickly covered
with lacteals of a different appearance. When dried
it seems as if the quicksilver were contained in small
cells, covering the whole internal surface of the in-
testine so completely that the point of a pin could
scarcely be placed between them.

CHAPTER XIV.
ON THE ORGANS OF RESPIRATION.

[Seite 259]

§ 174. The incessant continuation of the great
chemical process, by which oxygen, the true pabu-
lum vitae, is exchanged for hydrogen and carbone, is
essentially necessary to the wellbeing of the greater
part of animals. Yet the organs and mechanism,
by which this wonderful function is carried on, vary
very considerably1. In the mammalia after birth;
in birds, when they have left the egg; and in am-
phibia when completely formed, the chief organ of
this function is the lungs: in fish it is performed in
the gills; in most insects, in their tracheae; in the
vermes, in analogous, but at the same time very
different parts.

(A) Mammalia.

§ 175. The lungs of quadrupeds agree on the
whoIe in structure, form and connection, with
[Seite 260] those of the human subject. In the cetacea on
the contrary, and in the web-footed mammalia,
(as the manati), which approach most nearly to
them, they are distinguished by a firmer texture,
particularly of the investing membrane, and by
their peculiar form; since they are not divided
into lobes, but have an elongated and flattened ap-
pearance. They are adherent to the pleura, as well
as to the very strong and muscular diaphragm2.

(B) Birds.

§ 176. The respiratory organs of this class con-
stitute one of the most singular structures in the
animal economy, on account of several peculia-
rities, which they possess; but more particularly in
consequence of their connection with the numerous
air-cells, which are expanded over the whole body3.

The lungs themselves are comparatively small,
flattened, and adhering above to the chest, where
they seem to be placed in the intervals of the ribs;
they are only covered by the pleura on their under
surface, so that they are in fact on the outside of the
cavity of the chest, if we consider that cavity as
being defined by the pleura*: a great part of the
[Seite 261] thorax, as well as the abdomen is occupied by the
membranous air cells4, into which the lungs open
by considerable apertures. Those of the thorax
are divided, at least in the larger birds, by mem-
branous transverse septa, into smaller portions5;
each of which, as well as the abdominal cells has a
particular opening of communication with the air-
cells of the lungs , and consequently with the tra-
chea. The membranes of these cells in the larger
birds are provided here and there with considerable
fasciculi of muscular fibres, which have been re-
garded as a substitute for the diaphragm, which is
wanting in this class of animals6. They also serve
very principally, as we may ascertain by examining
large birds in a living state7, to drive back again
into the lungs, the air which they received in inspi-
ration; whence the repletion and depletion of the
[Seite 262] thoracic cells must alternate with those of the ab-
dominal cavities8.

§ 177. Betides these cells, a considerable portion
of the skeleton is formed into receptacles for air, in
most birds (for there are indeed exceptions and
considerable variations in the different genera and
species). This structure is particularly marked in
the larger cylindrical bones, as the scapula, clavicle
and femur. It is also found in most of the broad
and multangular bones of the trunk, as the ster-
num, ossa innominata, dorsal vertebrae, &c. All
these are destitute of marrow9 in the adult bird, at
least in their middle; so that the cylindrical bones
form large tubes, which are only interrupted to-
wards the extremities, by a sort of transverse bony
fibres: the broad bones are filled with a reticulated
bony texture, the cells of which are empty. They
have considerable apertures10 (most easily shewn in
those extremities of the cylindrical bones, which
are turned towards the sternum) communicating
with the lungs by small air-cells; which facts may
[Seite 263] be shewn by various experiments on living and dead
birds11.

These receptacles of air probably serve the pur-
pose of lightening the body of the bird in order to
facilitate its motions. This effect is produced in
most birds to assist their flight12; in some aquatic
species, for the purpose of swimming; in the ostrich
and some others, for running. Hence we find the
largest and most numerous bony cells in birds
which have the highest and most rapid flight, as the
eagle, &c. And hence also the bones of the bird
which has just left the egg, are filled with a bloody
marrow, which is absorbed soon after birth, entirely
in some, in others, particularly among the aquatic
species, at least for the greater part.

We may however conclude on the other hand,
that all these bony receptacles of air are not, like
those of the thorax and abdomen, immediately con-
nected with the respiration of the animals. For in
many birds the interval between the two tables of
the cranium contains air, while the apertures for
its admission are not connected with the lungs,
but merely with the Eustachian tube.

[Seite 264]

§ 178. The immense bill of some birds, which
are for that reason called levirostres, is provided
with air from the same quarter. This structure is
not therefore connected, as some anatomists13 have
supposed, with the organ of smelling, but forms a
part of the air-cells.

§ 179. Lastly the barrels of the quills also
contain air14. These are filled, in the bird which
has just quitted the egg, with a bloody marrow;
but they become hollow after its absorption, and
can be filled with air, or emptied at pleasure.
Hence arises the quick and voluntary erection of the
plumage in the turkey, bullfinch, &c. (See note (B).

§ 180. Besides the uses, which have been al-
ready pointed out, these receptacles of air diminish
the necessity of breathing frequently in the rapid
and long continued motions of several birds,
and in the great vocal exertions of the singing
birds15. They are also obviously serviceable in the
evacuation of the faeces, and probably assist in the
expulsion of the egg.

(C) Amphibia.

[Seite 265]

§ 181. The lungs of amphibia16 are distin-
guished from those of warm-blooded animals, both
by a great superiority in point of size, as well as by
a greater looseness of texture17: which circum-
stances are serviceable in swimming in many of these
animals. (See note (C).

§ 182. They have numerous projecting pro-
cesses in the chameleon18; and terminate behind in
an elongated bladder in the newt. The serpents,
at least for the most part, have only a single lung,
which forms an elongated bag19.

[Seite 266]

§ 183. In the tadpole, and the young of such
lizards as bring forth in water20, there are two or-
gans, which somewhat resemble the gills of a fish
(appendices fimbriatae Swammerdam)1. They are
connected to the sides of the neck, and hang loose
from the animal; they are not permanent, but are
gradually withdrawn into the chest, (within a few
days, in the reptiles of this country), where their
remains may still be perceived for some time2 near to
the true lungs3. Instead of the branchial opening,
[Seite 267] by which fishes again discharge the water, which
they have taken in at the mouth, some tadpoles
have for this purpose a canal on the left side of the
bead near the eye4; which must be distinguished
from the small tube on the lower lip, by which they
attach themselves to aquatic plants5.

(D) Fishes.

§ 184. Instead of lungs, this class of animals is
furnished with gills or branchiae; which are placed
behind the head, on both sides, and have a move-
able gill cover (apurculum branchiale), which is want-
ing in the order of pisces chondropterygii only. By
means of these organs, which are connected with
the throat, the animal receives its oxygen from the
air contained in the water6; as those animals which
breathe, derive it immediately from the atmosphere.
[Seite 268] They afterwards discharge the water through the
branchial openings (aperturae branchiales); and
therefore they are distinguished from animals of the
three preceding classes by this circumstance; viz.
that they do not respire by the same way that they
inspire.

§ 185. We have already shewn (§ 164) how
the gills receive the venous blood by means of the
branchial artery, and how this blood is sent into
the aorta after its conversion into the arterial state.
The distribution of these vessels on the folds and
divisions of the gills constitutes one of the most de-
licate and minute pieces of structure in the animal
economy7.

Each of the gills consists in most fishes8 of four
divisions, resting on the same number of arched
portions of bone or cartilage, connected to the os
hyoides. Generally there is only a single opening
for the discharge of the water; but in many cases,
particularly among the cartilaginous fishes, there
are several.

§ 186. Many animals of this order possess a
single or double swimming bladder9; which, at
[Seite 269] least in the fishes of this country, contains azotic
gas. It has not been hitherto determined, whether
it be surservient to any other functions, besides that
well known one, from which its name is derived.
In the mean time, like the air-receptacles of birds
it may be considered without impropriety in the
present division of the work.

It is placed in the abdomen, and closely attached
to the spine. It communicates generally with the
oesophagus, and sometimes with the stomach; by a
canal (ductus pneumaticus), containing in some in-
stances, as the carp, valves which seem to allow the
passage of air from the bladder, but not to admit its
entrance from without.

(E) Insects.

§ 187. That white-blooded animals indispensa-
bly require a species of respiration, would have been
inferred by analogy from the wonderful apparatus
of gills or tracheae, which have been discovered in
most orders of both classes of these beings. But in
many cases direct proof has been obtained on this
[Seite 270] point: experiment has actually proved the ex-
change of carbone for oxygen10.

White-blooded animals are moreover distin-
guished from those which have red-blood, by this
circumstance; that none of the former, as far as
we hitherto know, take in air through the mouth.

§ 188. Many aquatic insects11 as the genus can-
cer have a species of gills12 near the attachment of
their legs. The others, and particularly the land-
insects, which constitute, as is well known, by far
the greatest number of this class of animals, are fur-
nished with air-vessels, or tracheae, which ramify
over most of their body. These tracheae are much
larger and more numerous in the larva state of such
insects, as undergo a metamorphosis, (in which state
also the process of nutrition is carried on to the
greatest extent) than after the last, or, as it called,
the perfect change has taken place.

§ 189. A large air-tube (trachea) lies under
the skin on each side of the body of larvae, and
[Seite 271] opens externally by nine apertures (stigmata): it
produces on the inside the same number of trunks
of air-vessels (branchiae), which are distributed over
the body in innumerable ramifications13.

Both the tracheae and branchias are of a shining
silvery colour; and their principal membrane con-
sists of spiral fibres. The most numerous and mi-
nute ramifications are distributed on the alimentary
canal; particularly on the above-mentioned corpus
adiposum. (§ 126).

§ 190. There is great variety in the number
and situation of the external openings, by which in-
sects receive their air14.

In most instances the stigmata are placed on both
sides of the body. The atmospheric air enters by
[Seite 272] an opening at the end of the abdomen in several
aquatic larvae, and even perfect insects. A very
remarkable change in this respect takes place in se-
veral animals of this class during their metamor-
phosis. Thus in the larva of the common gnats
(culex pipiens), the air enters by an opening on the
abdomen: while in the nympha of the same animal,
it gains admission by two apertures on the head15.

(F) Vermes.

§ 191. In this class, which comprehends such
very different animals, the structure of the respi-
ratory organs is proportionally various16. Some
orders, as those which inhabit corals, the proper
zoophytes, and perhaps the intestinal worms, ap-
pear to be entirely destitute of these organs; so that
if any vital function, analogous to respiration, is
carried on in these animals, it must be effected by
methods which yet remain to be discovered.

§ 192. Those vermes, however, which are fur-
nished with proper organs of respiration, have the
same variety in their structure, which was remarked
[Seite 273] in insects. Some, as the cuttle fish17, oyster18, &c.
have a species of gills, varying in structure in dif-
ferent instances. But the greatest number have air-
vessels or tracheae.19 Several of the testaceous ver-
mes have both kinds of respiratory organs. In
some of the inhabitants of bivalve shells, as the genus
venus20, the air vessels lie between the membranes
of a simple or double tubular canal, found at the
interior part of the animal, and capable of voluntary
extension and retraction. It serves also for other
purposes, as laying the eggs. The margins of its
mouth are beset with the openings of the tracheae.
See note (E).


Additional Notes to the Fourteenth Chapter.

(A) The cartilaginous annuli of the trachea,
which are in general more complete, in the other
[Seite 274] mammalia, than in man, are perfect circles in birds,
and overlap each other at their upper and lower
margins. Hence the diameter of this part is not
affected by any twisting motion of the neck.

The air-vessels are considerably larger than in the
mammalia; and the substance of the lungs is not
divided into lobuli. The cartilages of the trachea
are lost before that tube enters the lung; and some
of its large branches open on the surface of the vis-
cous. I have observed in the ostrich that this
aperture was surrounded by circular muscular
fibres, which do not seem to have been hitherto
noticed.

(B) Besides the air-cells of the circumscribed
cavities, and of the bones, these cavities are formed
in some instances in the soft parts. They often ex-
tend from the axillary cell under the pectoral mus-
cles, and those of the scapula. ‘“In the eagle, hawk,
stork, lark, and other high flying birds, these cells
are very large; and in many of those birds these
are still larger cells, ascending under the integu-
ments of the neck, and passing beneath the skin of
the inside of the arm, and back of the shoulder.
In the stork we found these cells large enough to
admit the finger to pass a considerable way
down upon the inside and back of the wing.
They are also large in the owl and other birds of
prey.”’ Macartney in Rees’s Cyclopedia, art.
Birds.

[Seite 275]

The whole of this subject is explained at great
length, and with minute details in the above quoted
article.

(C) The amphibia are distinguished in all in-
stances by the great size of their air-vesicles. In
the frogs, lizards, and serpents, the lung consists of
a cavity, the sides of which are cellular. The
lower or posterior part of the organ either forms a
mere membranous bag (the parietes of which are
not cellular) or else the vesicles are larger at that
part than elsewhere. In the serpents the lung has
that elongated form, which characterises all the vis-
cera of these animals. A considerable portion of it
is a simple membranous cavity; and this is supplied
with arteries from the surrounding trunks. The
turtles have a more complicated structure; or one
which approaches more nearly to that of the warm-
blooded classes. The lungs are uniform in their
texture throughout; but the vesicles are very large.
The cartilaginous annuli of the bronchi terminate
before these vessels enter the lungs.

(D) Fourcroy found azotic with a small propor-
tion of carbonic acid gas in the carp: Lacepede
met with hydrogen in the tench; and pure oxygen
has been found in the shark. (Duncan’s Annals,
vol. 1, p. 393).

[Seite 276]

The air-bladder does not exist in many fishes;
whence Cuvier argues with justice against the
opinion which assigns this part an important office
in respiration. Indeed it seems much more pro-
bable that it is subservient to the motions of the
animal. For it is largest in such fishes, as swim
with considerable velocity. It is wanting in the
flat fishes; where the large lateral fins supply its
place, and in the shark, where its absence is com-
pensated by the size and strength of the tail. It
does not exist in the lamprey, which possesses
none of these compensations for its absence: that
fish therefore creeps slowly at the bottom of the
water.

It is found in some species of scomber; while
others want it: viz. the mackerel (scomber scom-
brus
). Its form varies ad infinitum in the different
genera and species. Its cavity is generally uni-
form: but sometimes divided by septa, as in
the silurus; and being even very cellular in the
diodon.

Its sides vary considerably in thickness; and are
sometimes bony, as in the cobitis fossilis.

There is generally a vascular and glandular body
situated in the cavity; which probably secretes the
contained air. In the perca labrax are two bodies
on the outside of the bag; giving rise to several
vessels, which contain air. These unite together,
and open into the cavity.

[Seite 277]

(E) In the terrestrial gasteropodous mollusca,
of which we may instance the snail and slug, there
is a cavity in the neck receiving air by a small
aperture, which can be opened or shut at the will
of the animal. The pulmonary vessels ramify
on the sides of the cavity.

CHAPTER XV.
ON THE ORGAN OF THE VOICE.

[Seite 278]

§ 193. Aristotle has correctly observed,
that those animals only, which possess lungs, conse-
quently the three first classes of the animal kingdom,
possess a true voice. Several genera and species even
of these are either entirely dumb; as the anteater1,
the mans, the cetacea2, the genus testudo, several
lizards and serpents; or they lose their voice in
certain parts of the earth; as the dog in some
countries of America, and quails3 and frogs4 in
several parts of Siberia.

(A) Mammalia.

[Seite 279]

§ 194. Most animals of this class5 have the
following circumstances in common: their rima
glottidis is provided with an epiglottis, which in
most instances has a peculiar muscle, arising from
the os hyoides, and not found in the human sub-
ject: the margins of this rima are formed by
the double ligamenta glottidis, (ligamenta thyreo-
arytaenoidea
); between which the ventriculi la-
ryngis are formed. The epiglottis does not exist in
most of the bat kind: and in some mouse-like ani-
mals, as the rell-mouse (glis esculentus), it is hard-
ly discernible. The superior ligamenta glottidis, as
well as the ventriculi laryngis are wanting in some
bisulca, as the ox and sheep.

§ 195. Some species of mammalia have a pe-
culiar and characteristic voice; or at least certain
tones, which are formed by additional organs. Of
this kind are certain tense membranes in some
animals; and in others peculiar cavities, opening
[Seite 280] into the larynx, and sometimes appearing as con-
tinuations of the ventriculi laryngis.

The neighing of the horse, for example, is ef-
fected by a delicate, and nearly falciform mem-
brane, which is attached by its middle to the thy-
roid cartilage, and has its extremities running
along the external margins of the rima glottidis6.

The peculiar found, uttered by the ass, is pro-
duced by means of a similar membrane; under
which there is an excavation in the thyroid carti-
lage. There are moreover two large membranous
facs opening into the larynx7.

The mule does not neigh like the mare, by which
it was conceived; but brays like the ass, which
begot it. It possesses exactly the same larynx as the
latter, without any of the peculiar vocal organs of
the mother: a fact, which like many others,
cannot be at all reconciled with the supposed pre-
existence of previously formed germs in the ova-
rium of the mother8.

[Seite 281]

The cat has two delicate membranes lying under
the ligamenta glottidis; which probably cause the
the purring noise peculiar to these animals9.

The pig has two considerable membranous bags
above and in front of the ligamenta glottidis10.

Several apes11 and baboons12, as also the rein-
deer13, have on the front of the neck, large single
or double laryngeal sacs, of various forms and divi-
sions, communicating with the larynx by one or
two openings between the os hyoides and thyroid
cartilage.

Some of the cercopitheci, as the C. Seniculus,
and beelzebub, have the middle and anterior part of
the os hyoides formed into a spherical bony cavity14,
by which the animals are enabled to produce those
[Seite 282] terrific and penetrating tones, which can be heard
at vast distances, and have gained them the name of
the howling apes.

(B) Birds.

§ 196. The most striking peculiarity in the vo-
cal organs of this class, and which belongs to all
birds with a very few exceptions; consists in their
possessing, what is commonly called, a double la-
rynx,
but which might be more properly described,
as a larynx, divided into two parts, placed at the
upper and lower ends of the trachea. They have
also two rimae glottidis.

§ 197. The superior, or proper rima glottidis
is placed at the upper end of the trachea; but is
not furnished with an epiglottis15. The apparent
want of this organ is compensated in several cases
by the conical papillae placed at both sides of the
rima.

§ 198. The apparatus, which is chiefly concern-
ed in forming the voice of birds, is found in the
[Seite 283] inferior or bronchial larynx16. This contains a
second rima glottidis, formed by tense membranes;
which may be compared in several cases, particular-
ly among the aquatic birds, to the reed at the
mouth of musical instruments. It is furnished ex-
ternally with certain pairs of muscles, varying in
number in the different orders and genera; and
with a kind of thyroid gland. The course and
proportionate length of the trachea, and particu-
larly the structure of the inferior larynx, vary very
considerably17 in the different species, and even in
[Seite 284] the two sexes, especially among the aquatic birds.
Thus, for example, the tame or dumb swan, (anas
olor
) has a straight trachea; whilst in the male of
the wild or whistling swan (cygnus), this tube
makes a large convolution, which is contained in
the hollow of the sternum (see § 55). In the
spoonbill (Platalea leucorodia) as also in the
Phasianus motmot, and others, similar windings
of the trachea are found, not enclosed in the
sternum. The males of the two genera anas
and mergus have at their inferior or bronchial
larynx a bony cavity,18 which contributes to
strengthen their voice.19 See note (A), at the
end of the chapter.

(C) Amphibia.

§ 199. The structure of the vocal organs in
this last class of animals, which possess a voice, is on
[Seite 285] the whole very simple; although it varies in se-
veral genera and species, and sometimes in the two
sexes. See note (B).

§ 200. The trachea forms different convolu-
tions in some of the testudines,20 and of the
crocodile kind. It is very short in the frog;
but longer in the male, than in the female: the
rima glottidis is also larger in the former. Liga-
menta glottidis exist in all the animals of this
class21.

§ 201. The males of some frogs are distinguished
by peculiar membranous bags. The tree frog (rana
arborea
) has a large sac in its throat; and the
green frog (rana esculenta) has two considerable
pouches in the cheeks, which it inflates at the time
[Seite 286] of copulation by two openings close to the rima
glottidis12. See note (C).


Additional Notes to the Fifteenth Chapter.

(A) ‘“A very little comparison of the me-
chanism of wind musical instruments, with the or-
gans of the voice in birds, will shew how nearly
they are allied to each other; and it may be
observed, that the found produced by some of
the larger birds is exactly similar to the notes
that proceed from a clarionet or hautboy in the
hands of an untutored musician. The inferior
glottis exactly corresponds to the reed, and pro-
duces the tone or simple found. The superior
larynx gives it utterance, as the holes of the instru-
ment; but the strength and body of the note de-
pend upon the extent and capacity of the trachea,
and the hardness and elasticity of its parts. The
convolution and bony cells of the windpipe, there-
fore, may be compared with the turns of a
French horn, and the divisions of a bassoon; and
they produce the proper effects of these parts in
[Seite 287] the voices of those birds, in which they are found.”’
Rees’s Cyclopedia, art. Birds.

(B) All the amphibia want the epiglottis.

(C) The chordae vocales are very large and dis-
tinct in the frog.

[Seite 288]

THE
ANIMAL FUNCTIONS.

[Seite 289] [Seite 290]

CHAPTER XVI.
ON THE BRAIN AND NERVOUS SYSTEM IN
GENERAL.

[Seite 291]

§ 202. This class of functions which constitutes
the leading character of animals, and has derived
its name from that circumstance, affords to our ob-
servation a more clear and manifest gradation, from
the most simple to the most compound structure,
than any others in the animal economy1.

§ 203. In some of the most simple animals of
the class vermes, particularly among what are called
Zoophytes, little or no distinction of similar parts2
(or structures) can be discerned; and we are un-
able to recognize any thing as a particular nervous
[Seite 292] system, or even as a part of such a system. The
power of sensation and voluntary motion, which
these possess, as well as any other order or class of
the animal kingdom, proves that the nervous matter
must be uniformly spread throughout their homo-
geneous substance. The almost transparent poly-
pes (hydra), which are often found in this country,
with a body of an inch in length, and arms or
tentacula, of a proportionate size, appear to consist,
when surveyed in the best light by the strongest
magnifying powers, of nothing but a granular struc-
ture (something similar to boiled Sago) connected
into a definite form by a gelatinous substance.

§ 204. In many other vermes, and in insects,
particular nerves can be distinguished, arising in
general from what is called the spinal marrow, the
superior extremity of which part, slightly enlarged,
constitutes the brain. The latter organ, however,
in both classes of cold and red-blooded animals, and
still more in those which have warm blood, has a
much more complicated structure, and a far greater
relative magnitude: all animals are however ex-
ceeded in both these points by the human subject,
which, according to the ingenious observation of
the learned Sömmerring3, possesses by far the
[Seite 293] largest brain in proportion to the size of the nerves
which arise from it.4 (See note (A) at the end of
the chapter.)

(A) Mammalia.

§ 205. The two large processes of the dura mater,
which form the falx and tentorium, possess a very
peculiar structure in some animals of this class. A
strong plate of bone, which is a process of the
neighbouring bones of the cranium, is contained
between their two laminae.

We have hitherto ascertained only one example
of such a formation of the falx, in the quadrupeds
[Seite 294] of this class: and this I discovered in the ornithor-
hynchus,
an animal which abounds in instances of
anomalous structure. Something similar is found
in the cetacea, at least in the porpoise5. The falx
itself descends to various depths between the hemis-
pheres in the different species6.

A bony tentorium cerebelli is found in a great
number of mammalia: but its size and extent vary
in the different species. It is formed by peculiar
osseous plates, extending from the vitreous table of
the parietal bones, and the petrous portions of the
ossa temporum. Its formation exhibits two kinds
of variety.

In some animals, for instance, it constitutes an
uniform bony partition, which leaves a quadrangu-
lar opening into the lower part of the cranium.
This is the case in most species of the cat and bear
kind; in the martin (mustela martes); in the
coaita (cercopithecus paniscus)7 and others.

[Seite 295]

It consists of three separate portions in other
animals, one of these pieces projects from the upper
and back part of the cranium, like a tile; the two
lateral portions arise from the petrous part of the
temporal bone. This structure is exemplified in
the seal8, dog, and horse.

In some cases, as in the pig, the rabbit, some
mice, &c. a rudiment of the last mentioned la-
teral portions may be observed; or at least the
ridge of the temporal bone is much sharper than
usual9.

§ 206. The peculiarities, which distinguish the
brain of the human subject from that of the mam-
malia10, consist chiefly in the circumstance, which
[Seite 296] has been already noticed, of its possessing a much
greater bulk in proportion to the nerves, which
arise from it; and in its being much larger when
compared with the cerebellum, and medulla spina-
lis11. (See note (D) at the end of the chapter.)

§ 207. Moreover, that remarkable and enigma-
tical collection of sandy matter, which is found in
the pineal gland12 of the human brain, almost in-
variably after the first few years of existence, has
been hitherto observed in a very few other mam-
malia, and those among the bisulca13.

[Seite 297]

§ 208. In the proper quadrupeds (the quadru-
mana
therefore being excepted), the anterior lobes
of the brain form two large processes (processus
mamillares
)14, from which the olfactory nerves of
the first pair proceed. These are of very consider-
able magnitude, particularly in the herbivorous
animals15. They contain a continuation of the la-
teral ventricle; which circumstance has formerly
given rise to great physiological errors16.

§ 209. The structure of the corpora quadrigemina,
and candicantia distinguishes the brain of herbivorous
from that of carnivorous quadrupeds. The nates very
considerably exceed the testes in size, in the former
class while these proportions are reversed in the
latter instance. The herbivora have a single large
eminentia candicans: there are two small ones in the
carnivora17. (See note (E) at the end of the
chapter.)

(B) Birds.

[Seite 298]

§ 210. The dura mater forms, in some birds,
a falciform process; which has been erroneously
asserted to be deficient in the whole class18. In the
cock of the woods (tetrao urogallus)19 it has a
bony structure, resembling that of the ornithor-
hynchus.

§ 211. The brain itself, considered altogether,
resembles that of the former class (even in forming
in some instances a kind of processus mamillares),
while, on the contrary, it is strikingly distinguished
from that of the following order. It differs, how-
ever, from that of the mammalia, not only in the
smoothness of its surface, and the want of convo-
lutions, but also in the structure of the optic tha-
lami. These eminences, which are nearly spheri-
cal, and hollow internally, are not contained in the
proper brain or cerebrum, but lie behind and
below that part. This structure is common to birds
[Seite 299] with the two classes of cold and red-blooded ani-
mals. Those eminences also, which in the mam-
malia are justly termed corpora striata, are of an
uniform colour in birds. (See note (F) at the end
of the chapter.)

§ 212. The brain of birds does not possess se-
veral parts, which are found in that of the mam-
malia; and the opinions of anatomists are much
divided concerning others, on account of variations
in their structure and appearance. The corpus
callosum, pons varolii, &c. come under the de-
scription of parts, which are certainly absent. The
existence of the fornix, pineal gland, corpora can-
dicantia, and quadrigemina, is a matter of dispute20.

(C) Amphibia.

[Seite 300]

§ 213. Anatomists have hitherto bellowed but
little labour, comparatively speaking, on the brain
of amphibia. It is small and simple, and consists
of five roundish eminences: viz. the two hemi-
spheres, the two thalami nervorum opticorum, ly-
ing behind these, and separate from them, and ex-
cavated by a ventricle; and the cerebellum, which
in both classes of cold red-blooded animals contains
no arbor vitae. The spinal marrow, compared
with the brain, is of astonishing magnitude in most
amphibia1. (See note (G) at the end of the
chapter.)

(D) Fishes.

§ 214. In this class of animals the brain does
not fill the cranium. Between the pia and dura
mater (which in most of the large fishes approaches
to a cartilaginous firmness) there is collected a salt
and greasy fluid, contained in a loose cellular tex-
ture, which seems to supply the place of the tunica
arachnoidea2.

[Seite 301]

§ 215. The structure of the brain varies in
the different genera and species; sometimes even in
the individuals of the same species. It consists of
several tubercles or lobuli disposed in pairs; and of
these, the five, which were described in the brain
of the amphibia, are the most constant3.

§ 216. In most fishes the optic nerves decus-
sate, (just like two fingers laid crosswise); a re-
markable peculiarity which has given rise to several
physiological investigations, and inferences4. (See
note (H) at the end of the chapter.)

[Seite 302]

These nerves have in some fishes the uncommon
structure of an investment of pia mater containing
very elegant longitudinal folds5.

The olfactory nerve sometimes forms a ganglion
just before it is distributed to the nose. The ga-
dus merluccius
and the carp6 afford examples of this
structure, which is remarkable inasmuch as no gang-
lia have been hitherto observed in the nervous
system of fishes.

§ 217. We must lastly mention those nerves,
which are distributed, in the electrical fishes, to
that wonderful apparatus of membranous cells,
filled with a gelatinous substance like white of egg,
and performing the office of a Leyden jar, or elec-
trical battery. These curious organs occupy the
[Seite 303] lateral fins of the torpedo7, and receive their ner-
vous supply from the fifth pair. In the electrical
eel (gymnotus), the electrical organ is found to-
wards the posterior part of the abdomen8, and its
nerves come from the medulla spinalis. In the
silurus electricus, it is placed between the skin and
muscles over the whole body, and its nerves are
derived from the eighth pair9.

(E) Insects.

§ 218. The general structure of the nervous
system in this class has been already mentioned
(§ 204).

The larvae, in which the subject has been most
completely investigated10, have a brain consisting
of two ganglia, contained in a horny cavity larger
than itself. The nervous cord, which in red-blood-
ed animals constitutes the medulla spinalis, proceeds
[Seite 304] from this point along the abdomen, forming in its
passage twelve simple ganglia, from which, and from
the two ganglia forming the brain, the nerves de-
rive their origin11.

(F) Vermes.

§ 219. Excepting those animals, which inha-
bit corals, and the proper zoophytes, most genera
of the other orders of this class are found to pos-
sess a distinct nervous system12: although former
[Seite 305] anatomists have expressly declared in several in-
stances that no such parts existed13. The structure
and distribution of the nerves possess in many cases
a surprising analogy to those of insects. The ner-
vous system of the sea-mouse (aphrodite aculeata),
for example, is very similar to that of the larvae14.
In others, it is more anomalous: thus, in the cut-
tle-fish, two large nervous chords arise from the
brain, and form in the bread two club-shaped gang-
lia; from which numerous nerves proceed15. (See
note (I).


Additions to the Sixteenth Chapter.

(A) As the works in which this most import-
ant physiological position is confirmed and eluci-
[Seite 306] dated, are not very generally known in this country,
I shall take the liberty of explaining it in a some-
what more detailed form.

The vast superiority of man over all other ani-
mals in the faculties of the mind, which may be
truly considered as a generic distinction of the hu-
man subject, led physiologists at a very early period
to seek for some corresponding difference in the
brains of man and animals. They naturally inves-
tigated the subject in the first instance, by comparing
the proportion, which the mass of the brain bears
to the whole body: and the result of this compari-
son in the more common and domestic animals was
so satisfactory that they prosecuted the inquiry no
further, but laid down the general proposition,
which has been universally received since the time
of Aristotle, that man has the largest brain in
proportion to his body. Some more modern phy-
siologists however, in following up this comparative
view in a greater number of animals, discovered se-
veral exceptions to the general position. They
found that the proportion of the brain to the body
in some birds exceeds that of man; and that several
mammalia (some quadrumana, and some animals
of the mouse kind) equal the human subject in this
respect.

As these latter observations entirely overturned
the conclusion, which had been before generally
admitted, Sömmerring has furnished us with an-
other point of comparison, that has hitherto held
[Seite 307] good in every instance: viz. that of the ratio, which
the mass of the brain bears to the nerves arising
from it.

Let us divide the brain into two parts; that
which is immediately connected with the sensorial
extremities of the nerves; which receives their im-
pressions, and is therefore devoted to the purposes
of animal existence. The second division will in-
clude the rest of the brain, which may be considered
as connecting the functions of the nerves, with the
faculties of the mind. In proportion then as any
animal possesses a larger share of the latter, and
more noble part; that is, in proportion as the or-
gan of reflexion exceeds that of the external senses;
may we expect to find the powers of the mind more
vigorous and more clearly developed. In this point
of view man is decidedly pre-eminent: here he ex-
cels all other animals that have hitherto been in-
vestigated.

All the simiae, says Sömmerring, are placed far
behind man in this respect. Although the brain in
some instances, particularly among the smaller
kinds, which have prehensile tails, is larger in pro-
portion to their body than that of the human sub-
ject; yet a very large share of that brain is required
of the immense nerves, which supply their organs
of sense and mastication. Let us remove that por-
tion of the brain, and a very small quantity will
remain.

The researches of the same author on animals in
[Seite 308] general have led him to conclude, that the quantity
of brain, over and above that which is necessary
for a mere animal existence – that part, in short,
which is devoted to the faculties of the mind, bears
a direct ratio, to the docility of the animal; to
the rank which it would hold in a comparative
scale of mental powers.

The largest brain, which Sömmerring has
found in a horse, weighed ℔ i. 4 oz. and the small-
est, which he has seen in an adult man, was ℔ ij.
5 1/2 oz. Yet the nerves arising from the former
brain were at least ten times larger than those of
the latter.

Generally speaking small animals have a larger
brain in proportion to their body than larger ones.
The pachydermata have it very small; and in red-
blooded animals, its size is very trifling when com-
pared with the body.

It forms in man from 1/22 to 1/33 of the body.
In some simiae 1/22
the Mole 1/36
Bear 1/263
Dog 1/161
Cat 1/94
Hare 1/ [...]
Rat 1/76
Mouse 1/42
Elephant 1/500
Pig 1/451–1/672
[Seite 309] In the Horse 1/400
Dolphin 1/5–1/102
Eagle 1/260
Sparrow 1/25
Chaffinch 1/27
Redbreast 1/32
Blackbird 1/63
Canary-bird 1/14
Cock 1/25
Duck 1/257
Goose 1/360
Tortoise 1/2240
Turtle 1/5688
Coluber natrix 1/792
Frog 1/172
Shark 1/2496
Pike 1/1305
Carp 1/560

(B) The following is the passage to which the
author refers in his ‘“Manual of Natural History”’.
‘“The extraordinary strength of the reproductive
power in several amphibia, (see note (G) to § 136)
and the astonishing facility, with which the process
is carried on, must be explained, if I mistake not,
from the great magnitude of their nerves, and the
diminutive proportion of their brain. The former
[Seite 310] parts are in consequence less dependent on the lat-
ter; hence the whole machine has less powers of
motion, and displays less sympathy: the mode of
existence is more simple, and approaches more
nearly to that of the vegetable world, than in the
warm-blooded classes: – but, on the contrary, the
parts possess a greater individual independent vi-
tality. Since, in consequence of this latter endow-
ment, stimuli, which operate on one part, or one
system, do not immediately affect the whole frame
by sympathy, as in warm-blooded animals; we are
enabled to explain the peculiar tenacity of life,
which is displayed under various circumstances in
this class; viz. frogs still continue to jump about
after their heart has been torn out; and turtles
have lived for months after the removal of the
whole brain from the cranium. The long conti-
nued power of motion in parts, which have been
cut off from the body, as in the tail of the water-
newt, and blind-worm, may be explained upon the
same principles”’. Edit. 6th, § 98, p. 221.

(C) ‘“It is difficult, (says the author in his
description of the bones) to give a physiological ex-
planation of the use of this bony tentorium. The
opinion, which has been generally adopted by ana-
tomists, that the structure in question belongs to
such animals only, as jump far, or run with great
velocity, and that it serves the purpose of protecting
the cerebellum from the pressure of the cerebrum
[Seite 311] in these quick motions, is obviously unsatisfactory.
It exists in the bear, which is not distinguished for
its activity: while several animals, which excel in
jumping or springing, do not possess it; viz. the
wild goat, (capra ibex), in which I could not dis-
cover the least trace of such a structure. Chesel-
den
ascribes it to predacious animals only (Anat.
of the Bones,
cap. 8); but I have already enumerated
several others. It may perhaps obviate the con-
cussion, which would arise from strong exertions
in biting; for such exertions are made in all the
animals, which possess this structure; even by the
horse in his wild state.”’ p. 118.

I have quoted these remarks on the generally
assigned use of the bony tentorium, because a semi-
lar mechanical explanation has been given, of the
falx and the tentorium of the human subject; viz.
that the former protects the hemispheres from
mutual pressure when the person lies with his head
resting on one side; and that the latter provides
against the compression of the cerebellum by the
superincumbent cerebrum. These explanations
are assigned in the present day by anatomists of
such distinguished reputation as Sömmerring and
Cuvier (de Corporis Humani Fabricâ, vol. 4, p. 27.
Léçons d’Anat. compar. tom. 2, p. 178). If the
futility of this piece of physiology were not suffi-
ciently proved by considering that the cranium is
accurately filled, and that there is consequently no
[Seite 312] room for its contents to fall from one side to the
other; it must immediately be rendered manifest
by Mr. Carlisle’s case; in which the falx was
entirely absent, and the two hemispheres united
throughout in one mass, without any perceptible
inconvenience during the patient’s life. (Trans-
actions of a Society for the Improvement of Medical
and Chirurgical Knowledge,
vol. 2, p. 212). I
have met with four instances, in which the anterior
half of the falx was deficient. This production of
the dura mater commenced in a narrow form about
the middle of the sagittal suture; and gradually
expanding, had acquired the usual breadth at its
termination in the tentorium. The two hemis-
pheres adhered by the pia mater covering their op-
posed plane surfaces; but were formed naturally in
other respects. A want of the falx has also been
recorded by Garengeot (Splanchnologie, tom. 2,
p. 24.)

(D) The proportion of the weight of the cere-
brum, to that of the cerebellum, is generally, al-
though not universally, greater in the human sub-
ject than in mammalia, as will appear from the
following instances taken from the second vol. of
Cuvier. In the human subject the cerebellum is

to the cerebrum, as 1 to 9
In the simia sciurea (squirrel-
monkey)

} 1 – 14
[Seite 313] Other simiae 1 to 6, 7 or 8
Dog 1 to 8
Cat 1 – 6
Beaver 1 – 3
Mouse 1 – 2
Hare 1 – 6
Boar 1 – 7
Cow 1 – 9
Sheep 1 – 5
Horse 1 – 7

The proportion of the cerebrum to the medulla
oblongata, as ascertained by a comparison of their
diameters, exhibits a more constant superiority in
the human subject over the other mammalia, than
the ratio of the Verebrum to the cerebellum.

In man the breadth of the medulla oblongata,
after the pons varolii, is to that of the brain,

as 1 to 7
Simiae 1 to 4 or 5
Dog 6 to 1
Cat 8 – 22
Rabbit 3 – 8
Pig 5 – 7
Deer 2 – 5
Cow 5 – 13
Horse 8 – 21

Yet the dolphin forms a remarkable and single
[Seite 314] exception to the general rule on this subject; for
in that animal the proportions are as 1 to 13. In
birds they are rather more than one to three.

(E) With the exception of man, and the simiae,
the mammalia cannot be said to have posterior lobes
of the brain. The cerebellum is seen behind the
cerebrum. The consequence of this is, that the
digital cavity or prolongation of the lateral ventri-
cle into the posterior lobe, is wanting.

The convolutions of the cerebrum do not exist
in the rodentia. The simiae only have an olfactory
nerve, arising, like that of man, in a distinct chord
from the brain. Other mammalia have a large
cortical eminence (processus mamillaris) filling the
ethmoidal fossa. As the cetacea have no organ of
smelling, their brain has neither olfactory nerve,
nor mamillary process.

(F) Cuvier represents the brain of birds to
consists of six tubercles visible exteriorly: viz.
the two hemispheres, the optic thalami, a cere-
bellum, and medulla oblongata.

(G) The dura mater forms no processes in the
amphibia, nor in the fishes.

(H) In the skate, the right nerve goes through
a fissure in the left; in bony fishes the decussation
[Seite 315] is more manifest, as one nerve merely lies on the
other without any intermixture of substance. The
fact has been noticed by Collins, Willis, and
several others: it is represented by Ebel in the
pike, carp, and Silurus glanis (Obs. Neurol. ex Anat.
comp.
tab. 2, fig. 2, 3, and 4: this dissertation
is contained in the 3d vol. of Ludwig’s Scriptores
Neurol. Minores
). It does not seem to have been
much investigated in birds and the amphibia. In
eight instances, where the eye of an animal had
been destroyed or injured, the optic nerve was
found to be altered in structure and appearance as
far as the union: and beyond that point the alter-
ation extended along the opposite nerve to the op-
posite thalamus. (See Ebel loc. cit. tab. 1.
fig. 1, and 2.) A similar appearance has been
found in a man. Sömmerring de Decussat.
Nerv. Optic.
in Ludwig’s Collection, tom. 1.

(I) In the class of insects, and of vermes, the
upper ganglion of the nervous chord, which repre-
sents the brain, is usually placed near the mouth or
oesophagus: which tube is surrounded by a nervous
chord proceeding from that ganglion.

CHAPTER XVII.
ON THE ORGANS OF THE SENSES IN GENERAL,
AND ON THAT OF THE SENSE OF TOUCH IN
PARTICULAR.

[Seite 316]

§ 220. Few subjects in comparative anatomy
and physiology have given rise to more various and
contradictory opinions, than the organs of sense in
some classes of animals1. Much misunderstanding
on this point has clearly arisen from the inconsider-
ate and unconditional application of inferences,
drawn from the human subject, to animals2. Thus
it has been supposed that those, which possess a
tongue, must have it for the purpose of tasting;
and that the sense of smell must be wanting, where
we are unable to ascertain the existence of a nose.
Observation and reflection will soon convince us,
that the tongue, in many cases (in the ant-eaters
among the mammalia, and almost universally in
[Seite 317] birds), cannot from its substance and mechanism
be considered as an organ of taste; but must
be merely subservient to the ingestion and degluti-
tion of the food. Again in several animals, parti-
cularly among insects, an acute sense of smell seems
to exist, although no part can be pointed out in the
head, which analogy would justify us in describing
as a nose.

§ 221. However universally animals may pos-
sess that feeling, which makes them sensible to the
impressions of warmth and cold, very few possess,
like the human subject, organs exclusively appro-
priated to the sense of touch, and expressly con-
structed for the purpose of feeling, examining, and
exploring the qualities of external objects.

This sense appears, according to our present state
of knowledge, to exist only in three classes of the
animal kingdom; viz. in most of the mammalia,
in a few birds, and probably in insects.

(A) Mammalia.

§ 222. The structure of the organ of touch is
the most perfect, and similar to that of the human
subject, in the quadrumana. The ends of their
fingers, particularly of the posterior extremities, are
covered with as soft, and delicately organized a skin,
as that which belongs to the corresponding parts
in man.

[Seite 318]

Several of the digitata are probably provided with
this sense. The organization of the under sur-
face of the front toes of the racoon (ursus lotor),
and the use which the animal makes of those parts,
prove this a assertion.

It is not so clear that we are authorised in con-
sidering the snout of the mole3 and pig4, not to
mention the tongue of the solidungula and bisulca5,
or the snout of these and other animals6, as true
organs of touch according to the explanation above
laid down7.

§ 223. There would be more reason for ascrib-
ing this sense to the proboscis of the elephant. (See
note ( A) at the end of the chapter.)

I think, however, that the ornithorhynchus
clearly possesses an organ of touch. In this curious
animal, as in the duck, &c. the sense in question
[Seite 319] resides in the integuments, which cover the ex-
panded portion of its jaws, particularly the upper
one; this part is most copiouly supplied with nerves
from the fifth pair, and chiefly from its second
branch, distributed just in the same manner as they
are on the corresponding parts of the swimming
birds.

(B) Birds.

§ 224. The structure of the organ of touch
in the ornithorhynchus, which has been just de-
scribed, is exactly similar to that of geese and ducks.
The bill of these birds is covered with a very sensible
skin, supplied with an abundance of nerves from
all the three branches of the fifth pair. This ap-
paratus enables them to feel about for their food in
mud, where they can neither see nor smell it.

(C) Amphibia.

§ 225. It has been said of serpents8 with more
ingenuity than truth, that their whole body is a
hand; by which they gain just notions of the tan-
gible properties of bodies. There is much more
foundation for stating that the sense of touch, which
is here meant, does exist in any of the amphibia.

(D) Fishes.

[Seite 320]

§ 226. Concerning this class, the remark,
which was made on the amphibia, may be repeated;
although several fishes possess an acute feeling on
the abdomen, and in the lips9.

(E) Insects.

§ 227. All the observations and investigations
of the structure of the antennae, those peculiar
organ, which exist universally in the more perfect
insects; ad of the use, which these animals gene-
rally apply them to; lead us inevitably to the con-
clusion, that they really are, what their German
name10 imports, proper organs of touch; by which
the animal examines and explores surrounding ob-
jects11. Such organs are particularly necessary to
insects, on account of the insensibility of their ex-
ternal coat, which is generally of a horny con-
sistence; and also from their eyes being destitute
in most instances, of the power of motion.

(F) Vermes.

[Seite 321]

§ 228. It seems more doubtful whether the
tentacula of several vermes, and particularly the
arms of the cuttle fish12, can be considered as or-
gans of touch, in the more limited sense, to which
we have confined that word13.


Additional Note to the Seventeenth Chapter.

(A) Bats have been supposed to possess a
peculiar power of perceiving external objects, with-
out coming actually into contact with them. In
their rapid and irregular flight amidst various
surrounding bodies, they never fly against them:
yet it does not seem that the senses of hearing,
seeing, or smelling, serve them on these occasions;
for they avoid any obstacles with equal certainty
when the ear, eye, and nose are closed. Hence
[Seite 322] naturalists have ascribed a sixth sense to these
animals. It is probably analogous to that of touch.
The nerves of the wing are large and numerous,
and distributed in a minute plexus between the
integuments. The impulse of the air against this
part may possibly be so modified by the objects near
which the animal passes, as to indicate their situa-
tion and nature.

CHAPTER XVIII.
ON THE TONGUE.

[Seite 323]

§ 228. We are not justified in considering the
tongue as an organ of taste in all animals, because
it is subservient to that function in the human sub-
ject, and in some other instances. We have already
observed, that this organ in many cases merely
serves for taking in the food1; and it is at least very
doubtful whether it possesses the sense of taste in
several others. Yet, on the contrary, we should
not be warranted in denying the existence of the
sense in these animals, nor even in such as are en-
tirely destitute of a tongue: for this function may
be exercised by other parts2. Less, however, can
[Seite 324] be concluded with any certainty a priori, on this,
than on any of the five senses.

(A) Mammalia.

§ 229. No animal possesses a tongue exactly
like that of the human subject. The form of the
organ differs considerably in the simiae, being
longer and thinner; and the papillae, which cover
its upper surface, are very different3.

[Seite 325]

§ 230. Most of the herbivorous mammalia,
particularly among the bisulca, have their tongue
covered with a firm and thick cuticular coat; which
forms numberless pointed papillae directed back-
wards. These must assist, according to their con-
sistence and direction, at least in the animals of this
country, in tearing up the grass. Animals of the
cat kind have their tongue covered with sharp and
strong prickles, which must enable the animal to
take a firm hold. Similar pointed processes are
found in some other animals; as in the bat-kind,
and the opossum.

There seems to be no doubt that in all the mam-
malia which we have now considered, the tongue is
an organ of taste, at least towards its anterior
part.

The toothless animals, on the contrary, as the
ant-eater* and manis, which swallow their aliment
[Seite 326] whole, have a long worm-like tongue, which is ob-
viously capable of no other use than that of taking
their food.

(B) Birds.

§ 232. All birds possess a tongue: for even
the pelican, in which its existence has been de-
nied, possesses a manifest rudiment of the organ.
Probably, however, it serves the purpose of an or-
gan of taste in very few genera. Yet this is the
case with some predacious and swimming birds; as
also with most of the psittaci; which possess a soft
thick tongue covered with papillae, and moistened
with a salivary fluid: they really taste different flu-
ids, and soft kinds of food, and select that which it
the most agreeable.

[Seite 327]

§ 233. In several other birds, on the contrary,
the tongue is horny, stiff, not supplied with nerves,
and consequently unfit for an organ of taste. One
striking example will supply the place of many.
The tongue of the toucan (Ramphastos) is some-
times several inches in length, yet scarcely two lines
broad at its root. It has the appearance, through-
out, of a piece of whalebone; and its margins are
fibrous.

§ 234. The form4 and mechanism of the tongue
vary much in the different genera and species of this
class. Two instances deserve particular notice:
that of the wood-pecker, and the cock of the woods.
The tongue of the former bird is generally said to
be very long; but it is not so. That part, which
corresponds to the tongue of other birds, is remark-
ably short: it is merely a sharp-pointed horny
portion, with its sides barbed. Behind this is a
very singular os hyoides; of a slender appearance,
but having very long crura. It consists of five car-
tilaginous portions; viz. one single piece, and two
pairs. In the quiescent state of the organ, the for-
[Seite 328] mer lies in a fleshy, and very extensile sheath of the
bill. The first pair of cartilages is articulated with
this; and they are placed at the sides of the neck.
The second pair, commencing from these, run com-
pletely over the cranium, under the integuments;
and advancing from behind, forwards, their con-
verging extremities are placed together in a kind of
groove, and commonly terminate anteriorly by an
attachment to the right side of the upper jaw. This
posterior pair of cartilages may therefore be com-
pared to steel springs, which actuate the whole or-
gan5. When the tongue is to be darted out, the
anterior pieces are drawn together, and enter the
sheath of the single portion, extended for their re-
ception. The tongue is thus elongated, and admits
of being thrust out some inches.6

The tongue of the cock of the woods is still
more singular; that organ, together with the la-
rynx, lies deep in the oesophagus, but admits of
being quickly elevated and thrust forth by means of
considerable muscles7.

(C) Amphibia.

[Seite 329]

§ 235. We shall select a few examples of the
chief varieties in this class of animals.

The crocodile’s tongue (the very existence of
which has been denied from the time of Herodo-
tus
down to Hasselquist) is small; possesses
very little motion; and is in a manner adherent
between the two sides of the lower jaw8. The sa-
lamander resembles this. A very different structure
is presented in the curious tongue of the chamaeleon;
the mechanism of which may be compared in some
respects with that of the woodpecker. Yet its form
is very different; for the anterior extremity of the
organ is club-shaped; and is hollowed out on its
upper surface9. (See note (A) at the end of the
chapter.)

The tongue of some testudines is thickly co-
[Seite 330] vered on its anterior margin with long fibrous
papillae10.

The soft, flat, and fleshy tongue of the frog, lies,
in the quiescent state, in a direction from before,
backwards. It is firmly attached behind the arch
of the lower jaw; and its loose end is turned back-
wards, so that the semilunar notch of its anterior
margin corresponds to the rima glottidis. They
seize their prey by turning the tongue forwards, and
thrusting it out of the mouth.

§ 236. The tongue of serpents is attached, and
situated in the same manner as in the frog11: but it
is round and slender: its apex is bifid, and the
root reds in a kind of fleshy sheath, being capable
of protrusion and retraction at pleasure12.

(D) Fishes.

§ 237. There is little to be said concerning the
tongue of this, and the two following classes. It is
[Seite 331] doubtful whether it be an organ of taste, and in
what degree it may serve that purpose.

It appears at least in fishes to possess no manifest
papillae13; and in many of this class is covered with
teeth.

That, which is commonly called the tongue in
some fishes, as the carp, is a glandular body, attached
to the palate, and extremely irritable in the living
animal14.

(E) Insects.

§ 238. The organ which is commonly consi-
dered as the tongue of insects15, merely serves for
taking in the food16. But the accurate observations
of professor Knoch17, render it very probable that
the posterior pair of palpi, or feelers, possesses the
power of taste in several of this class.

(F) Vermes.

[Seite 332]

§ 239. In the mouth of some mollusca,18 and
snails19, an organ is found, which has generally from
its situation been taken for the tongue. But none
of the observations, which have been hitherto ad-
duced respecting its functions, are sufficiently de-
cisive to justify us in setting it down as an organ of
taste.


Additional Note to the Eighteenth Chapter.

(A) The tongue of the chameleon displays a
very curious mechanism. It is contained in a
sheath at the lower part of the mouth; and has its
extremity covered with a glutinous secretion. It
admits of being projected to the length of six inches;
and is used in this manner by the animal, in catch-
ing its food; which consists of flies, &c. It is
darted from the mouth with wonderful celerity
and precision; and the viscous secretion on its ex-
tremity, entangles the small animals which consti-
tute the food of the chameleon.

CHAPTER XIX.
ON THE ORGAN OF SMELLING.

[Seite 333]

§ 240. The sense of smelling prevails much more
extensively in the animal kingdom, than that of
taste: since it not only a assists several genera in se-
lecting their food, which they have not afterwards
the power of tasting; but is also of service in find-
ing out proper objects for the satisfaction of their
sexual appetite. Yet there is much doubt respect-
ing the organs of this sense in the two classes of
white-blooded animals1.

§ 241. We can determine the degree of acute-
ness of this sense by the inspection of the cranium,
in the four-footed mammalia2, (taking the term in
its most extensive sense, in which it will include the
[Seite 334] quadrumana and bats). Three circumstances prin-
cipally determine our judgement on this point.

1st, The structure of the ethmoid bone, and par-
ticularly the number and arrangement of those
openings in its superior or horizontal lamina, which
transmit the filaments of the olfactory nerve. 2ndly,
The formation of the inferior conchae narium, or
turbinated bones. 3rdly, The existence and relative
magnitude of those cavities of the internal nose, par-
ticularly the frontal sinuses, which contribute to the
organ of smelling.

§ 242. The hedge-hog and mole, the animals
of the weasel, bear, dog, and cat-kinds, most of the
bisulca, and the elephant, afford examples of a very
complicated formation of the ethmoid bone; both
in regard to the elegant structure of its cribriform
lamella, and to the wonderful convolutions of its
turbinated portions; which procure as large a sur-
face as possible within the confined space of the na-
sal cavity, for the application of the Schneiderian
membrane. All these animals are well known for
the remarkable acuteness of their sense of smelling.

The ethmoid bone is remarkably narrow, and im-
perfectly developed in most of the quadrumana. As
there is not sufficient space left for it between the
orbits, which lie close together3, (§ 20.) it is
[Seite 335] placed deeper in the nose; so that the olfactory
nerves descend between the orbital portions of
the frontal bone, as in a canal, the bottom of
which is formed by the cribriform lamella, small
and inconsiderable, and perforated by few aper-
tures4.

The cetacea have no ethmoid bone. They want
also the first pair of nerves; and the first branch of
the fifth pair seems to perform its functions.

§ 243. The conchoe narium inferiores are more
or less convoluted, in proportion to the greater or
less complication in the structure of the upper ones.
They are remarkably large in the bisulca5; and
much convoluted in most of the predacious ani-
mals6. They are both large and wonderfully com-
plicated in the seal7.

[Seite 336]

§ 244. The frontal sinuses8 of the elephant9 are
larger than those of any other animal; the pig,
which has an acute sense of smelling, comes next in
order in this respect. Most of the mammalia,
which possess proper horns, have these cavities ex-
tending more or less into those processes of the fron-
tal bone, on which the horns are formed: this
structure is particularly observable in the wild goat
(capra ibex). They are generally large in the
bisulca10, the solidungula, and in most of the con-
vorous mammalia. They are abfent on the con-
trary in the seal; in most of the rodentia; and the
cetacea.

§ 245. The anomalous structure of the ele-
phant’s proboscis, or trunk, and the blowing-holes
of the cetacea, must be noticed here; as these parts
constitute prolongations and external openings of
the nose.

[Seite 337]

The former organ consists of two canals, sepa-
rated from each other by an intervening partition.
Innumerable muscular fasciculi running in two di-
rections, occupy the space between these and the
integuments. There are fibres of a transverse
course, passing like radii from the canals to the in-
teguments11; and others, which run in a more lon-
gitudinal direction, but have their extremities turned
inwards12. The former extend the trunk, without
causing any contraction of the canals; the latter
bend or contract it; and both tend to bestow on
it that wonderful mobility, which it possesses in
every direction. (See note (A) at the end of the
chapter.)

The blowing hole of the cetacea is not a pecu-
liar organ, distinct from the nasal openings, as several
naturalists have imagined, but one and the same with
these13. It does hot however seem to be designed
for an organ of smelling, but merely to be subser-
vient to respiration, and to the expulsion of the water
which enters the mouth with the food14. (See
note (B).

(B) Birds.

[Seite 338]

§ 246. The nostrils open in the several genera
of this class in very different parts of the upper
mandible; in some, as the puffin (alca arctica),
the openings are placed at the margins of the bill,
and are so small, that they might be easily over-
looked15.

§ 247. Birds have no proper ethmoid bone:
their olfactory nerves pass through the orbits to
the nose, and are distributed on the pituitary mem-
brane, which covers two or three pairs of bony16 or
cartilaginous17 conchae narium (bullae turbinatae or
tubulatae vesicae18) of various forms and sizes19.
(See note (C).

(C) Amphibia.

§ 248. The organ of smelling is less clearly
developed in this class of animals. Yet we discover
[Seite 339] two cartilaginous eminences, which may be com-
pared to the conchae of warm-blooded animals20.
(See note (D).

(D) Fishes.

§ 249. Most of these seem to have double nos-
trils on each side: for the openings are furnished
with a valve-like moveable membrane, which ap-
pears like a partition1.

§ 250. Behind these is generally found, instead
of conchae narium, a very elegantly plaited mem-
brane, disposed in semicircular folds, and having the
olfactory nerves distributed on it2.

[Seite 340]

(E) Insects.

§ 251. Numerous facts have long ago proved
that several insects can distinguish the odorous pro-
perties of bodies even at considerable distances.
But the organ, in which this sense resides, has not
hitherto been clearly pointed out.

Since all red-blooded terrestrial animals smell
only through the medium of the air, which they
take in in inspiration, several naturalists have sup-
posed, that the stigmata of insects are to be consi-
dered as organs of smelling3. Others ascribe
this office, and with some probability, to the ante-
rior pair of palpi4.

(F) Vermes.

§ 252. Several animals of this class appear to
have the sense of smelling: as many land-snails (he-
lix pomatia
5, &c.). But the organ of this sense is
hitherto unknown; perhaps it may be the stigma
thoracicum.

Additional Notes to the Nineteenth Chapter.

[Seite 341]

(A) Cuvier has given a more detailed descrip-
tion of the elephant’s trunk in the last vol. of his
Leçons d’Anat. comp. p. 283–289; and has also
represented the part in the 29th plate of the same
volume.

The more longitudinal fibres are divided at short
intervals by tendinous intersections, which enable
the animal to bend any part of the organ, and to
give it any requisite degree of curvature. The same
structure will confer a power of bending different
parts of the trunk in opposite directions; indeed
there is no kind of curvature which may not be
produced by these longitudinal fibres. These fasci-
culi occupy the external surface of the organ. The
transverse fibres are not all arranged like radii round
the canals; but some pass across from right to left,
and must therefore affect the diameter of those tubes
by their action. The whole of these muscular fas-
ciculi are surrounded and connected together by a
white, uniform, adipous substance. The transverse
ones are not more than a line in thickness. If the
number of these, which appears on a transverse
section, be ascertained; and if those portions of the
longitudinal fasciculi, which pass from one tendon
to another, be reckoned as separate muscles, (for
they must have a separate power of action) the
[Seite 342] whole trunk will contain about thirty or forty thou-
sand muscles; which will account satisfactorily for
the wonderful variety of motions which this admi-
rable organ can execute, and for the great power
which it is capable of exerting.

(B) The blowing-hole of the whales serves as
well for respiration, as for the rejection of the water
which enters with their food. In consequence of its
situation at the top of the head, it is easily elevated
beyond the surface of the sea, while the mouth is
usually entirely under water.

The opening in the bones of the head is divided
into two by a partition of bone; and is furnished
with a valve opening outwards. On the outside of
this opening are two membranous bags, lined with
a continuation of the integuments, and opening ex-
ternally. The water, which the animal wishes to
discharge, is thrown into the fauces, as if it were to
be swallowed; but its descent into the stomach is
prevented by the contraction of the circular fibres
of the oesophagus. It therefore elevates the valve
placed at the entrance of the blowing holes, and
distends the membranous bag, from which it is
forcibly expelled by surrounding muscular fibres.

This apparatus occupies the situation, which in
other mammalia is filled by the nose; which organ,
together with the sinuses of the head, the olfactory
nerve, &c. is entirely wanting in these animals.

[Seite 343]

(C) The olfactory nerve of birds comes off from
the anterior extremity of the front lobe of the brain,
and has therefore some analogy with the processus
mamillaris of quadrupeds. It passes along a canal
to the nose, and is distributed in a very beautiful
and distinct manner on the pituitary membrane in
many instances, as in the crane.

(D) The origin and course of this nerve are
much the same in reptiles as in birds. In the turtle
it is a large, strong, and fibrous nerve, and its rami-
fications in the nose are easily traced.

CHAPTER XX.
ON THE ORGAN OF HEARING.

[Seite 344]

§ 253. We should naturally expect to find an
organ of hearing in most classes of animals1, when
we consider the various services, which this sense
performs; as, that of indicating the approach of
danger, of conducting predaceous animals to their
prey, and of bringing the two sexes together for
the purpose of copulation, &c. Red-blooded ani-
mals, without any exception, possess this organ.
Analogous parts are found in some of the white-
blooded; and several others certainly can hear,
[Seite 345] although the organ of that sense has not been
hitherto been ascertained.

(A) Mammalia.

§ 254. The four-footed mammalia are the only
animals, which possess true external ears; and,
even here, several instances occur, in which these
parts are wanting; particularly among such as live
in the water, or under ground. They are not
met with, for instance, in most of the seals, in the
walrus, manati, duck-billed animal (ornithorhyn-
chus
), and mole. On the contrary some have
been said to want external ears, who really possess
them, as the marmota or mus citilllus. Another
error has been committed, in representing the ears
of a species of bat, belonging to this country, (ves-
pertilio auritus
) as double2; whereas they are only
of an immense size. The essential parts of the
external ear agree on the whole with those of the
human subject*; but their general form is subject
to great variety. In very few, except the quadru-
mana, do they resemble those of man; but this is
[Seite 346] the case in the porcupine. The cartilage is stronger,
and more elastic in its structure in the human ear,
than in that of any other animal, in proportion to its
size. In some instances, as the opossum (didelphis
marsupialis
), they are merely membranous.

§ 255. The external auditory passage is furnished
with a valve in such animals as go frequently
into the water, by which they can close it when
they dive. The water-shrew (sorex fodiens) affords
an example of this structure. The length, breadth,
and direction of the meatus vary considerably in
the different genera. It is very long and singular-
ly tortuous in the duck-billed animal3. (See note
(A), at the end of the chapter.)

§ 256. It is hardly necessary to state that all
mammalia have a membrana tympani, a tympanum
situated within this, and an Eustachian tube passing
from that cavity to the fauces; except in the ce-
tacea, where it opens in the blowing hole. (§ 245.)
The membrane is rather concave on its outer sur-
face, being slightly depressed in the middle. All
the animals of this class are furnished with the two
fenestrae; the f. ovalis, which is filled by the base
of the stapes; the f. rotunda, at which the scala
tympani of the cochlea commences.

[Seite 347]

§ 257. In most of the four-footed mammalia,
there is connected with the tympanum, another ca-
vity; which, according to the situation of the bony
organ that contains it, must be compared to the
mastoid cells in the temporal bone of man.

In several animals this organ forms a mere bony
cavity (bulla ossea): viz. in the dog, cat, martin,
squirrel, hare, and some of the bisulca. An at-
tempt at this structure is to be seen in the cerco-
pithci. In the horned cattle, on the contrary, and
in the pig, the cavity is divided into cells by numer-
ous bony plates, which somewhat resemble the
divisions in a ripe poppy head4.

§ 258. Warm-blooded quadrupeds have, like
the human subject, three5 ossicula auditus; which
on the whole resemble in form those of man. But
the duck-billed animal, whose structure in every
respect is so anomalous, has only two6; and on the
contrary one or two additional small bones are
[Seite 348] occasionally found, particularly in some bisulca7.
(See note (C).

§ 259. The part which is termed the labyrinth
of the ear, as far as it has been hitherto investigated
in the four-footed mammalia, seems to agree on
the whole, in its essential parts, with that of the hu-
man subject. But the cochlea (which belongs in-
deed exclusively to this class) has in some cases a
turn more than in man; not to mention other dif-
ferences of less importance8.

§ 260. In addition to what has been observed
respecting the Eustachian tube of the cetacea, some
other parts of the organ of hearing exhibit such pe-
culiarity in these animals, and deviate so widely from
those of warm-blooded quadrupeds, that they re-
quire particular notice9.

[Seite 349]

Their want of external ear is well known. The
opening of the meatus is remarkably small. The
bony part of the organ is loosely connected to the
skull in the dolphin and porpoise; and it is com-
pletely separate in the proper whales (balaenae) and
cachalot (physeter).

The hard bony substance, which was formerly
very erroneously called lapis manati or tiburonis,
is merely the tympanum, and bulla ossea of the
whale.

The ossicula auditus, and the labyrinth, particu-
larly the bony canals (canales semicirculares),
which for this very reason were long overlooked,
are remarkably small in the cetacea.

(B) Birds.

§ 261. This whole class10, as well as the follow-
ing ones, has no cartilaginous external ear, which
belongs, therefore, exclusively to the mammalia.

[Seite 350]

This apparent deficiency is compensated in birds,
particularly in those of the rapacious kind, by the
regular arrangement of the feathers round the
opening of the meatus. Several also, chiefly of
the last mentioned class, and particularly among
the owls, have a peculiar valve placed at the open-
ing, partly of a membranous, partly of a muscular
structure11.

§ 262. The membrana tympani of birds is con-
vex on its outer surface; and the tympana of the
two ears are connected together by the air-cells
of the cranium12.

They have a single ossiculum auditus, connecting
the membrana tympani with the fenestra ovalis, and
consequently supplying the place of the malleus
and stapes of the mammalia.

The part corresponding to the malleus, is gene-
rally cartilaginous, and not provided with any tensor
tympani.

The eustachian tubes have a kind of common
opening on the arch of the palate.

§ 263. The labyrinth is distinguished by large
[Seite 351] canals, projecting from the cranium, and not hollow-
ed out of a hard bony substance, as in the mamma-
lia; and by the want of cochlea. Instead of the last
mentioned part, birds have a short, obtuse, and
hollow bony process, passing obliquely backwards
from the vestibulum; and divided by a partition,
like the cochlea of mammalia, into two scalae, one
of which terminates at the fenestra rotunda. This
part receives a portion of the auditory nerve, as the
cochlea does.

(C) Amphibia.

§ 264. The different orders, and genera of this
class13 exhibit greater variety in the structure of the
organ of hearing than the two former, or the follow-
ing class. Hence the principal variations must be
separately considered.

§ 265. Turtles, frogs, and most species of the li-
zard kind, possess, besides semicircular canals, a tym-
panum and eustachian tube, like warm-blooded ani-
[Seite 352] mals. Both the latter parts, however, as well as
the ossicula auditus, are wanting in the salamander.

The membrana tympani of the turtle resembles a
mass of cartilage; and is covered externally by the
common integuments. Their single ossiculum re-
sembles that of birds.

Frogs have a large membrana tympani level
with the surface of the body; a wide opening
the Eustachian tube at the fauces; two cartilaginous
ossicula; and a rudiment in the vestibulum of those
soft stony substances, which are found in a more
conspicuous form in the lizards and serpents, and
in the three following classes.

The crocodile is the only instance, in which there
is a sort of external meatus in the class amphi-
bia. This animal, as well as the lizards, possesses
ossicula, and the above-mentioned stony concretions
in the vestibulum.

The want of tympanum in the salamander has
been already mentioned. The foramen ovale in
this animal is merely closed by a portion of carti-
lage, and the vestibulum contains a soft stone.

§ 266. The serpents, with a very few excep-
tions, as the blind-worm14 (anguis fragilis) have
neither tympanum, nor Eustachian tube. They
have a kind of rudiment of ossiculum.

(D) Fishes.

[Seite 353]

§ 267. It is only in some genera of cartilagi-
nous fishes, viz. the skate anil shark, that a tubular
appendix of the vestibulum is continued backwards
and outwards, so as to represent a rudiment of a
tympanum.

§ 268. The other animals of this class15 have
no similar part; but their organ of hearing consists
of three large canals, which are generally seen to
project into the cavity of the cranium. Opposite
to the termination of the auditory nerves on the
vestibulum, one, two, or three neatly formed stones
are found. These are as white as porcellaine, par-
ticularly in several of the bony fishes, and very dry
and brittle in their texture16.

[Seite 354]

§ 269. The internal ear of fishes is distinguished
from that of the other three classes of red-blooded
animals, by this remarkable peculiarity; that it
grows, as the fish increases in size, and consequently
that its magnitude is in the direct ratio of the
bulk and age of the animal. (See note (D).

(E) Insects.

§ 270. There is no doubt that several insects
possess the sense of hearing17; but the organ of
this sense is very uncertain. In some of the larger
animals of the genus cancer a part can be distin-
guished, which seems to be analogous to the vesti-
bulum of the former classes18. A small bony tube
is found on each side at the root of the palpi: its
external opening is closed by a firm membrane;
and it contains a membranous lining, on which a
nerve arising from a common branch with that of
antennae, is expanded. The latter circumstance
[Seite 355] might favour an opinion that the antennae them-
selves are organs of hearing: but this is refuted by
considering the exquisite sense of hearing, which
some insects possess, who have no true antennae, as
the spiders; and by experiments on others, which
shew that the sense of hearing is not weakened by
removing the antennae19.

(F) Vermes.

§ 271. In the sepia only has any thing been
hitherto discovered at all like an organ of hearing.
In the cartilaginous ring, to which the large tenta-
cula of the animal are affixed, two oval cavities ap-
pear. In each of these is a small bag containing
a bony substance, and receiving the termination of
nerves, like those of the vestibulum in fishes20.


Additional Notes to the Twentieth Chapter.

(A) The cetacea are the only mammalia,
which have not a bony external meatus. The tube
[Seite 356] is cartilaginous in these animals, and so small that
its external orifice will about admit a pin in the
dolphin. It arrives at the tympanum after a wind-
ing course through the fat, which lies under the
skin. It is probable that the found gains admission
to the ear in these animals, rather through the Eu-
stachian tube, than through this very narrow
meatus externus. That tube opens at the blowing
hole, and its furnished with a valve that prevents
the admission of the water, which the animal ex-
pels through this opening.

(B) The following is the passage to which the
author refers as expressing his opinion on this sub-
ject. I insert it in this place, because the work in
which it is found is not common in this country,
and is in the German language. ‘“Anatomists gene-
rally describe a fourth bone (the lenticulus, or
os orbiculare) as intervening between the long
leg of the incus, and the head of the stapes.
Repeated and accurate examinations have con-
vinced me that this part is only an epiphysis of
the incus. It is often wanting, even in such os-
sicula auditus, as appear in other respects to be
of the most perfect formation; for instance, in
those of negroes and North American sa-
vages, which I have now before me. When it
exists in the adult subject, it can only be sepa-
rated by the employment of some force; and a
[Seite 357] microscopical examination of the surfaces shews
that the lenticulus has been broken from the incus.
Sometimes, indeed, I have found a really separate
ossiculum between the incus and stapes; but this
cannot, in my opinion, be considered as belong-
ing to the ordinary natural structure, any more
than those other supernumerary ossicula, which
are found not infrequently, both in man and
animals.”’ Beschreibung der Knochen, p. 144.

(C) Cuvier describes a portion of bone as
passing between the crura of the stapes, from one
side of the fenestra ovalis to the other, in the mole,
and marmot (in which last animal it is of consider-
able size). (Léçons d’Anat. comp. p. 489, tom.
2). Mr. Carlisle has represented this part in
the marmot, and he dates its existence likewise in
the guinea pig. (Philos. Trans. 1805, pt. 2).

Cuvier has also found that the stapes is nearly
solid in the cetacea; and that there is no perfora-
tion in the walrus. This peculiarity of structure
seems to belong to such mammalia as live in water;
for the seal has it in a smaller degree. Léçons
d’Anat. comp.
tom. 2, p. 505. Carlisle, loc.
citat.
gives drawings of the stapes in these ani-
mals.

The second ossiculum of the ornithorhynchus ap-
proaches very much in its form to the single bone
of birds. (Carlisle, loc. cit.).

[Seite 358]

(D) The membranous canals and vestibulum
of the amphibia and fishes, are much smaller than
the bony or cartilaginous cavities, in which they
reside. Hence these parts can be discerned and
demonstrated much more easily in these animals
than in mammalia and birds, where they are closely
surrounded by the bone.

CHAPTER XXI.
ON THE EYE.

[Seite 359]

§ 272. A sensibility to the impressions of
light is common to all those animals, which in a
natural state are exposed to this element: it appears
at least very evidently to exist in some of the most
simple zoophytes, as the armed polypes (hydra):
but the power of perceiving the images of external
objects is confined to those who are provided with
eyes for their reception. Nature has bellowed on
some species even of red-blooded animals, a kind of
rudiment of eyes, which have not the power of
perceiving light: as if in compliance with some
general model for the bodily structure of such ani-
mals. This circumstance at least has been asserted
of the blind rat (marmota typhlus) among mamma-
lia; and of the myxine glutinosa among fishes.

§ 273. Since the eye1 is a very complicated
[Seite 360] organ, particularly in the red-blooded animals, we
shall first speak of those peculiarities, which affect
the globe itself, its membranes and humours: and
afterwards consider the surrounding parts, as the
eye-lids, lacrymal passages, &c. For some general
observations on the situation and formation of the
eye-balls, &c. see note (A) at the end of the
chapter.

(A) Mammalia.

§ 274. It has been long known2, that the scle-
rotica, in several quadrupeds of this class, as in the
human subject, is not throughout of equal strength;
but that its posterior is much thicker than its ante-
rior part. It has also been conjectured, that this
structure might influence what are called the inter-
nal changes of the eye:
by which the form of the
eyeball, consequently the length of its axis, and the
respective situation of the lens, are adjusted accord-
ing to the proximity or remoteness of the object, or
in reference to any other relations. I flatter my-
self, that I have ascertained the truth of this conjec-
[Seite 361] ture, by discovering the admirable structure of the
sclerotica in warm-blooded quadrupeds, which have
not only the power of seeing at various distances,
but also in two media of such different density as
air and water. In the eye of the Greenland seal,
where I first noticed the fact3, the cornea was thin
and yielding; the anterior segment of the sclero-
tica, or that which is immediately behind the latter
membrane, was thick and firm; its middle circle
thin and flexible; and lastly, the posterior part very
thick, and almost cartilaginous. The whole eye-
ball is surrounded with very strong muscles; and
we can easily understand how their action, varied
according to circumstances, produces the requisite
changes; how the axis of the eye is shortened,
when the animal sees in air, by bringing the lens
nearer to the back of the globe, in order to obviate
the strong refraction, which the rays of light expe-
rience in passing from the thin medium of air into
the thicker one of the eyes, and vice versa.

The sclerotica of the cetacea is distinguished by
the great thickness of its posterior part: when the
[Seite 362] eye-ball equals an orange in size, the back of this
membrane is an inch thick; so that, although the
globe be spherical, the space containing the vitreus
humor is of a different form. As the sclerotica ap-
proaches to the cornea, it becomes thinner. Its pos-
terior part presents a very singular structure, con-
sisting of very firm tendinous threads and laminae,
most closely interwoven, and of more than cartila-
ginous hardness4 towards the sides.

The extent of the cornea, when compared to
that of the sclerotica, varies in the different species
of mammalia. It seems to be greatest in the por-
cupine (hystrix cristata), where the cornea extends
over half the globe.

§ 275. A peculiar structure, which appears
hitherto to be unique, has been lately discovered in
the eye of the East-Indian rhinoceros. Four ten-
dinous fasciculi arise from the back of the sclerotica,
and expand anteriorly, so as to join and form a kind
of muscular membrane, which is lost in the choroid
at the broadest diameter of the globe5. This is
[Seite 363] probably connected with the internal changes of
the organ.

The choroid coat consists more plainly in the
cetacea, than in any other mammalia, of two distinct
laminae; of which the internal (membrana ruyschi-
ana
) is covered with a dull tapetum.

§ 276. The inner surface of the choroid coat
possesses, towards the back of the eye, in several
general of this class, particularly in those carnivo-
rous animals, which prey by night, and even in the
bisulca, the most brilliant yellow-green and sapphire-
blue colours; forming what is called the tapetum
lucidum
6. The coloured portion of the choroid is
only partial, and the rest of the membrane is covered
with pigmentum nigrum, as usual7.

[Seite 364]

In consequence of this structure, less light will be
absorbed; and it must, on the contrary, be reflected
from the tapetum against the retina, which lies in
front of that membrane. (See note (B) at the end
of the chapter.)

§ 277. The retina exhibits in some quadru-
peds, viz. the hare and rabbit, very distinct and
elegant fibres or striae of medullary substance, tak-
ing for the most part a transverse direction8. The
remarkable foramen centrale, which Sömmerring
discovered in the human retina, has been since de-
monstrated in the eyes of several quadrumana, where
these organs are directed forwards, and have their
axes parallel9.

[Seite 365]

§ 278. The iris, an organ of very peculiar
structure, exhibits in the different genera and species
of mammalia more numerous and interesting vari-
eties than any other part of the eye. The colours
of its anterior surface, which are peculiar to the dif-
ferent genera, vary in the races and varieties of
domestic animals, although less strikingly than in
the human subject. These variations are connected,
as in the latter instance, with the colour of the hair;
so that in spotted dogs, rabbits, &c. a mixture of
colours will be seen in the iris.

The substance of the part varies in thickness in
the different genera. In no instance have I hitherto
been able to discover true muscular fibres; the ex-
amination of the part in the elephant and whale
having afforded in this respect the same result, as
[Seite 366] the tender and almost transparent iris of the white
rabbit.

In the eye of the seal the ciliary vessels are not dis-
tributed in the substance of the iris; but lie on its
anterior surface, and form a considerable plexus,
which is visible without any injection10.

The pupil in the bisulca, solidungula, cetacea, &c.
is transverse; in animals of the cat kind, particu-
larly in a clear light, it is oblong: not to mention
other trivial peculiarities, as the small villous ap-
pendix, covered with pigmentum nigrum11, which
is sometimes seen on the middle of the superior
margin of the pupil, particularly in the horse12. (See
note (C) at the end of the chapter.)

§ 279. The corpus ciliare, and particularly the
folds of its internal surface, with their numerous
and elegantly arranged blood-vessels, constitutes one
of the most wonderful parts of the eye, although its
[Seite 367] functions, which must undoubtedly be of the highest
importance, are hitherto involved in mystery. Its
more minute differences in the genera, which have
been hitherto examined, are too numerous to be re-
counted; and they could not be understood with-
out delineations13. Among other instances, those
of the elephant and horse may be mentioned, on
account of the remarkable beauty and delicacy of
their structure.

§ 280. The size of the cristalline lens varies in
proportion to that of the vitreous humor; and some
times very considerably. I have found the largest
lens in this point of view in the comparatively
small eye of the opossum (didelphis marsupialis);
the whale has the smallest. No mammalia have it
so slightly convex on the surface as the adult man.
In the cat, hare, the bisulca, the horse, opossum, and
seal, it becomes more and more convex according
to the series, in which I have named these animals.
Lastly, in the cetacea it is nearly spherical14. (See
note (D).

[Seite 368]

It is curious to observe the regularity, with which,
in some species, the lens divides into certain seg-
ments commencing from its centre, in consequence
of being dried or immersed in acids15.

§ 281. A lacrymal gland16 exists in all animals
of this class. Several quadrupeds have, indeed, an
additional one, besides that which is found in the
human subject. Some have no puncta lacrymalia;
and the elephant has neither lacrymal bag nor os
unguis
17. (See note (E).

§ 282. The nictitating membrane (membrana
nictitans, palpebra tertia,
seu interna, periophthal-
mium
), ot which only a rudiment exists in the
quadrumana, and the human subject, is very large
and moveable in some quadrupeds18. This is the
case in animals of the cat kind, in the opossum,
the seal, and particularly in the elephant.

[Seite 369]

§ 283. The relative magnitude of the true
eye-lids varies considerably in animals of this class.
The lower, which is very large in the elephant, is
equally small in the horse. In the latter animal,
as well as in most quadrudeds, it has no cilia;
while in the quadrumana, the elephant, the giraffe,
and others, both eye-lids possess eye-lashes.

(B) Birds.

§ 284. The eyes are very large in this class of
animals19 and consequently the bony orbits are of
great magnitude in proportion to the skull.

In the birds of prey they have a peculiar form,
which is similar to that of the chalice, or cup used
in the communion service: the cornea, which is
very convex, forms the bottom of the cup; and the
the posterior segment of the sclerotica resembles its
cover20.

[Seite 370]

§ 285. This peculiar form arises from the cur-
vature and length of the bony plates, which, as in
all other birds1, occupy the front of the sclerotica;
lying close together, and overlapping each other.
These bony plates form in general a flat, or slight-
ly convex ring; being long and curved in the
accipitres, they form a concave ring, which gives
the whole eye-ball the above-mentioned form2.

§ 286. The distinction between certain parts
of the eye, where the membranes have been sup-
posed to be continuous, appears more plainly in some
birds, than in any other animals. Thus I have
found the boundaries of the choroid coat and iris
very clearly defined in the horned owl (strix bubo):
and those of the margin of the retina, and the pos-
terior border of the ciliary body very distinct in
the toucan (ramphastos tucanus). (See note (F).

§ 287. A great peculiarity in the eye of birds
consists in the marsupium3 (pecten plicatum, in
[Seite 371] French, la bourse, le peigne), the use of which has
not been hitherto very clearly ascertained. It arises in
the back of the eye, proceeding apparently through
a slit in the retina; it passes obliquely into the vitre-
ous humor, and terminates in that part, reaching
in some species to the capsule of the lens. The
figure of its circumference is a truncated quad-
rangle. Numerous blood-vessels run in the folds
of membrane which compose it; and the black
pigment by which it is covered, suggests an idea
that it is chiefly destined for the absorption of the
rays of light, when they are too strong or daz-
zling.

§ 288. Birds have large lacrymal passages,
which terminate on the surface of the palate4.

Their nictitating membrane5 is furnished with
two very manifest muscles6. (See note (G).

In some species, as the common fowl, the turkey,
goose, and duck, the lower eye-lid, which contains
[Seite 372] a peculiar small lamina of cartilage, is the most
moveable; in others on the contrary, as in the
parrots, and ostrich, the upper has the most exten-
sive motion.

Very few birds have cilia in both eye-lids: they
are found in the ostrich, the falco serpentarius, the
razor-billed blackbird (crotophaga ani) and in
some parrots. (See note (G).

(C) Amphibia.

§ 289. Little is hitherto known concerning the
peculiarities in the structure of the eye of this
class7.

In some reptiles and serpents of this country,
the common integuments form, instead of eye-lids,
a kind of firm window, behind which the eye-ball
has a free motion.

In the green turtle8 (testudo mydas) the sclero-
tica has a bony ring at its anterior part, composed
like that of birds, of thin osseous plates. These
animals possess very large lacrymal glands, and a
very moveable membrana nictitans; in which cir-
cumstance the frog resembles them9. (See note
(H).

[Seite 373]

(D) Fishes.

§ 290. The peculiarities in the eye of fishes10,
which belong either to the whole class, or to most
of the genera and species, consist in the division of
their choroid coat and retina into several manifestly
distinct laminae; and in the existence of two small
organs within the eye, which belong exclusively to
this class.

§ 291. The choroid coat, which in man is a
simple membrane, and in some other warm-
blooded animals, particularly in the cetacea, a
double one, consists in fishes of three distinct laminae.
The inner layer forms a true tunica ruyschiana;
the middle one (membrana vasculosa of Haller),
is perfectly distinct both from the former, and
from the exterior coat; which latter must be com-
pared with the proper choroid of all red-blooded
animals. Even this last is continued anteriorly
into the iris, and possesses in many species the well
known brilliant gold and silver colours.

[Seite 374]

The retina is easily separable into two laminae;
of which the external is medullary, and the internal
consists of a fibrous texture.

§ 292. The two other peculiarities belong ex-
clusively to the eye of fishes; and are common at
least to the whole bony division of these animals. A
body, generally resembling in shape a horse-shoe,
lies between the internal and middle layers of the
choroid; some have thought it muscular, and
others glandular. The tunica ruyschiana gives
origin to a vascular membrane, resembling in its
form a bell (campanula of Haller). This goes to-
wards the lens, and has, therefore, some resem-
blance to the marsupium of birds.

No true ciliary body is found, at least in the
bony fishes.

§ 293. The crystalline lens of most fishes is
very large in comparison with the size of the eye-
ball, and nearly or entirely spherical. The vitreous
humour
on the contrary is small, and the aqueus in
many cases is hardly discernible.

§ 294. The following may be enumerated as
instances of remarkable peculiarities in the eyes
of particular genera and species of fishes. The
firm transparent laminae of common integuments,
behind which the eye-balls move, as in some am-
[Seite 375] phibia12 (§ 289); the articulation of the globe
on a stalkof cartilage in the skate, and shark13: the
curtain (operculum pupillare) in the eye of the
skate14, which can be let down so as to cover the
pupil: and the unique structure of the lobitis anab-
leps,
where the cornea is divided into two portions,
and there is a double pupil with a single lens15.
(See note (I).

(E) Insects.

§ 295. Two kinds of eyes, very dissimilar in
their structure, are found in this class16. One sort
is small and simple (stemmata): the others, which
are large, seem to consist of an aggregation of
smaller eyes17; for their general convexity is di-
vided into an immense number of small hexagonal
convex surfaces, which may be considered as so
[Seite 376] many distinct corneae. The first kind is formed in
different numbers in most of the aptera, as also in
the larvae of many winged insects. When these
undergo the last or complete metamorphosis, and
receive their wings, they gain at the same time the
large compound eyes. Several genera of winged
insects, and aptera (as the larger species of mono-
culi18) have stemmata besides their compound
eyes.

§ 296. The internal structure has hitherto
been investigated only in the large polyedrous
eyes19. The back of the cornea (which is the part,
divided in front into the hexagonal surfaces, called
in French, facettes) is covered with a dark pigment.
Behind this are numerous white bodies, of an hexa-
gonal prismatic shape, and equal in number to that
of the facettes of the cornea. A second coloured
membrane covers these, and appears to receive the
expansion of the optic nerve.

§ 297. Further investigation is, however, re-
[Seite 377] quired in order to shew how these eyes enable the
insect to see; and to determine the distinctions be-
tween two such very different organs20.

(F) Vermes.

§ 298. The cuttlefish only, of this whole class1,
has been hitherto shewn to possess true eyes; the
nature of which cannot be disputed. They re-
semble on the whole those of red-blooded animals,
particularly fishes; they are at least incomparably
more like them than the eyes of any known insects;
yet they are distinguished by several extraordinary
peculiarities2. The front of the eye-ball is covered
with loose membranes instead of a cornea; the iris
is composed of a firm substance, which seems like
a continuation of the sclerotica; and a process pro-
[Seite 378] jects from the upper margin of the pupil, which
gives that membrane a semilunar form.

The corpus ciliare is very completely formed.

In all other vermes the eyes are entirely wanting,
or their existence is very doubtful. Whether the
black points, at the extremities of what are called
the horns of the common snail3 are organs which
really possess the power of vision, is still proble-
matical4.


Additional Notes to the Twenty-first Chapter.

(A) Large animals have small eye-balls in pro-
portion to their size: this is very remarkably the
case with the whales. Those which are much un-
der ground have the globe also very small; as the
mole and shrew: in the former of these instances
its existence has been altogether denied; and it is
not in fact larger than a pin’s head.

The eyes of man and the simiae are directed for-
wards: in the latter animals indeed they are placed
nearer to each other than in the human subject.
The lemur tarsius has them more closely approxi-
[Seite 379] mated than any other animal. All other mammalia
have these organs separated by a considerable inter-
val, and directed laterally. The same circumstance
obtains in birds with the exception of the owl, who
looks straight forwards. They are placed laterally
in all reptiles; Their situation varies much in
fishes: they look upwards in the uranoscopus:
they are both on the same side of the body in the
pleuronectes: but in general their direction is la-
teral.

The form of the globe varies according to the
medium, in which the organ is to be exerted. In
man and the mammalia, it deviates very little from
the spherical figure. In fishes it is flattened on its
anterior part; in birds it is remarkably convex in
front, the cornea being sometimes absolutely hemi-
spherical. The convexity of the crystalline is in an
inverse ratio to that of the cornea. Thus in fishes
it is nearly spherical, and projects through the iris,
so as so leave little or no room for aqueus humor:
the cetacea, and those quadrupeds and birds, which
are much under water, have this part of the same
form. The aqueus humor being of the same den-
sity with the medium in which these animals are
placed, would have no power of refracting rays of
light, which come through that medium: its place
is supplied by an encreased sphericity of the lens.
In birds these circumstances are reversed: they in-
habit generally a somewhat elevated region of the
[Seite 380] atmosphere; and the rays, which pass through this
thin medium are refracted by the aqueus humor,
which exists in great abundance. Man and the
mammalia, which live on the surface of the earth,
hold a middle place between these two extremes.

(B) The tapetum occupies the temporal side of
the bottom of the eye-ball; i.e. it is placed exteri-
orly to the entrance of the optic nerve. It exists in
the carnivorous and ruminating animals; in the so-
lipeda, pachydermata, and cetacea. In the dog,
wolf, and badger, it is of a pure white, bordered by
blue.

(C) The figure of the pupil is transversely ob-
long in the ruminating animals, and the horse: it
is heart-shaped in the dolphin.

(D) The crystalline is smaller in the eye of man
than in any animal, and it is largest in the fishes.

The following numbers give the proportions of
the three humours, measured on the axis of the eye,
after it had been frozen.

Aqueus Humor. Crystalline. Vitreus Humor.
Man, 5/22 4/22 15/22
Dog, 5/21 8/21 8/21
Cow, 6/37 14/37 18/37
Sheep, 4/17 11/17 12/17
Horse, 9/43 16/43 18/43
Owl, 8/27 11/27 8/27
Herring, 1/7 5/7 1/7
[Seite 381]

The greater convexity, which the author ascribes
to the seal and whales, arises from their inhabiting
the water; so that they require an organ of vision
like that of fishes.

(E) In addition to the lacrymal gland, several
mammalia have another body, called the glandula
Harderi.
This is situated nearer to the nose, and
pours out a thick whitish fluid near the third eye-
lid. It joins the proper lacrymal gland in the hare
and rabbit; but is distinguished by its whiter colour.
The ruminantia, carnivora, and pachydermata, have
it likewise.

The ducts of the lacrymal gland admit of very
easy demonstration in the larger quadrupeds, where
they open to the number of sixteen or more, by
orifices that will admit a large bristle.

The hare and rabbit have, instead of puncta la-
crymalia, a slit opening into the lacrymal canal.

The cetacea want the lacrymal apparatus entirely,
as their eyes are preserved in a moist state by the
element in which they live.

The muscles of the eye-ball are the same in num-
ber in the simiae as in man: but other mammalia
possess an additional one, termed the suspensorius
oculi.

This muscle is of a conical form. Its origin,
which takes place from the margin of the optic fo-
ramen, represents the apex of the cone; and its
[Seite 382] insertion into the posterior half of the sclerotica,
constitutes the basis. It fills up therefore the inter-
val left between the four recti, and surrounds com-
pletely the optic nerve. In several of the carnivora,
and the cetacea, it is divided into four portions; so
that these animals may be said to have eight straight
muscles. It must enable the animals which possess
it to draw the globe back into the orbit; and hence
it has sometimes been called the retractor of the
eye.

A remarkable peculiarity occurs in the conjunc-
tiva of the zemni (mus typhlus). It is covered
with hair as in other parts of the body, so that the
eye, which is, indeed, exceedingly small, seems to
be completely useless. A similar structure is also
found in two fishes, the murena cecilia, and myxine
glutinosa (Gastrobranchus caecus, Cuvier). Léçons
d’Anat. comp.
tom. 2, p. 394.

(F) The ciliary processes of birds are not very
prominent: they consist rather of striae, than of
loose folds. They are always closely connected to
the crystalline capsule. There is no tapetum in
this class.

The colour of the iris varies in the different
species of birds; and in many instances possesses
great brilliancy. It has a power of voluntary mo-
tion in the parrot.

[Seite 383]

The retina passes obliquely through the sclerotica,
in a sheath of the latter membrane.

(G) Birds possess both a lacrymal gland, and
glandula Harderi. The latter is considerably the
largest; and is usually placed between the elevator
and adductor muscles of the globe. It furnishes
a thick yellow fluid, which is poured from a single
duct, opening on the inner surface of third eye-
lid.

The eye-lids are closed in most birds by the ele-
vation of the inferior palpebra, which is the largest.
This eye-lid has a peculiar depressor muscle arising
from the bottom of the orbit. The owl, and the
goatsucker are among the few in which the upper
eye-lid descends.

The third eye-lid, or membrana nictitans is a thin
semitransparent fold of the conjunctiva; which,
in the state of rest, lies in the inner corner of the
eye, with its loose edge nearly vertical, but can
be drawn out so as to cover the whole front of the
globe. By this, according to Cuvier, the eagle is
enabled to look at the fun.

It is capable of being expanded over the globe
of the eye by the combined action of two very sin-
gular muscles, which are attached towards the
back of the sclerotica. One of these, which is
called from its shape the quadratus, arises from the
upper and back part of the sclerotica; its fibres
[Seite 384] descend in a parallel course towards the optic nerve,
and terminate in a semicircular margin, formed by
a tendon of a very singular construction: for it has
no insertion, but constitutes a cylindrical canal.
The second muscle, which is called the pyramidalis,
arises from the lower and back part of the sclerotica
towards the nose. It gives rise to a long tendin-
ous chord, which runs through the canal of the
quadratus, as in a pulley. Having thus arrived at
the exterior part of the eye-ball, it runs in a cellular
sheath of the sclerotica along the under part of the
eye, to the lower portion of the loose edge of the
membrana nictitans, in which it is inserted.

By the united action of these two muscles, the
third eye-lid will be drawn towards the outer angle
of the eye, so as to cover the front of the globe;
and its own elasticity will restore it to its former
situation.

(H) The ciliary processes are hardly percepti-
ble in the turtle; but they leave an elegant inpres-
sion on the surface of the vitreous humor. They
are distinct and long in the crocodile. The blood-
vessels are visible on the surface of the iris;
where they form a distinct plexus in the croco-
dile.

The optic nerve forms a tubercle within the
sclerotica; from which the retina commences.

The number, &c. of the eye-lids varies consider-
[Seite 385] ably in this class. Serpents have none. The tur-
tle and crocodile have three like those of birds.
The frog and toad have three; of which the third
is much the largest and most moveable.

The turtle has a very large lobulated lacrymal
gland. Serpents have nothing of this kind.

(I) The continuation of the conjunctiva over
the cornea admits of being demonstrated in the eel.
For it comes off some times with the rest of the
skin of the head in stripping off he integuments
of this animal.

CHAPTER XXII.
ON THE MUSCLES.

[Seite 386]

§ 299. The heart and other muscular viscera
have been already treated of. We have only to
speak here of the proper muscles, which are des-
tined to the performance of the voluntary motions.
As the details of myology do not come within the
plan of this work, the present chapter will include
only a few remarks on the peculiarities in the mus-
cular structure of the different classes, and of some
particularly remarkable species1.

(A) Mammalia.

§ 300. The degree of resemblance between the
muscles of the mammalia2, and those of the human
[Seite 387] subject, may be inferred, in any particular instance,
by comparing the skeleton of the animal with that
of man. The similarity is greatest, on the whole, in
the quadrumana. Yet these are distinguished by
the smallness of their buttock and calf of the leg;
the strength and convexity of which parts constitute
peculiar beauties in the human form3. (See note
(A) at the end of the chapter.)

§ 301. Of the muscles which do not exist in
man, nor as far as we hitherto know, in the quadru-
mana; but which on the contrary are found at least
in the greatest number of quadrupeds4; the cuta-
neous expansion of the trunk (panniculus carnosus,
expansio carnea, musculus subcutaneus
), and the sus-
[Seite 388] pensorius oculi
5 deserve particular mention. (For
the particular description of the latter muscle, see
the chapter on the eye.)

§ 302. Among such, on the contrary, as are
found only in particular genera and species, the
most remarkable are the extremely numerous
muscles of the prehensile tails of some cercopitheci
(sapajous, belonging to the simiae of Linnaeus), and
other South American and Australasian mam-
malia6; those which we have already described in
the trunk of the elephant7; and that which belongs
to the epiglottis of several mammalia (cerato-epiglot-
tidaeus
)8.

§ 303. Other muscles, which are common to
most orders of the class, are distinguished in some
[Seite 389] species by remarkable strength, which adapts them
for peculiar kinds of motion. This is the case with
the gluteus medius9 of the horse; which, in connec-
tion with some others, particularly the gemellus10,
enables the animal to kick out backwards with such
astonishing force; with the immensely strong flexors
of the beaver’s tail, &c. (See note (B).

(B) Birds.

§ 304. The muscles in this class are distin-
guished by possessing a comparatively weak irri-
table power, which is soon lost after death; and by
their tendons becoming ossified, as the animal grows
old, particularly in the extremities, but sometimes
also in the trunk. I have observed this to a very
remarkable degree, in the crane11.

§ 305. The most remarkable circumstances in
the myology of this class12 have been incidentally
[Seite 390] mentioned in previous parts of the work. For in-
stance, muscles which are peculiar to birds; as
those of the membrana nictitans*; or such as are
deficient, as the diaphragm; or distinguished by
their remarkable size and peculiar form, as the pec-
toral muscles.

(C) Amphibia.

§ 306. The two chief divisions of this class are
distinguished from each other by a remarkable dif-
ference in their muscular structure, which arises
from a corresponding diversity in the skeleton. In
the reptiles, for instance, and particularly in the
turtles13 and frogs, where the trunk of the skeleton
possesses but little mobility, the muscles are very few
in number. Not only the diaphragm, but also the
[Seite 391] muscles of the abdomen and chest are wanting in
the genus testudo. The other muscles are, however,
of vast strength in this genus. In the serpents on
the contrary, they are more uniform and thin; and
more numerous beyond all comparison, in conse-
quence of the vast number of vertebrae and ribs,
and the want of all external organs of motion.

(D) Fishes.

§ 307. The muscles of this class14 are distin-
guished from those of animals which breathe by
means of lungs, not only by receiving a smaller sup-
ply of blood, and consequently being of a paler
colour; but also by their disposition in layers, and
by the uniformity15 of their substance, which in
general is destitute of tendinous fibres. This struc-
ture, together with the number and bulk of their
muscles, is well calculated to support that great ex-
penditure of strength and exertion, which is a
necessary consequence of the peculiar abode, and
whole economy of these animals16.

[Seite 392]

(E) Insects.

§ 308. The observations which have just been
made concerning the uniformity, number, and
strength of the muscles of fishes, will hold equally
good, on the whole, of insects; but under other
modifications, and generally in a more striking de-
gree17. In the few, which have been hitherto
investigated with a view to this subject, some dif-
ferences have been observed. The immensely
strong muscles of the claw in the crab and lobster18,
bear considerable analogy to those in some organs
of red-blooded animals: while the muscles of other
insects, as may be seen in the larvae, are distinguished
by a peculiar bluish white colour, and flattened
form. Their great number concurs also with these
characters in distinguishing them from those of the
former classes. Lyonet19 reckoned 4061 in the
larva of the cossus20: and 2186 of these belong to
the alimentary canal.

(F) Vermes.

[Seite 393]

§ 309. The arrangement of the muscular sys-
tem of the mollusca1 has considerable analogy, on
the whole, to that of the larvae of insects. Those
which inhabit shells, have, moreover, peculiar muscles
connecting them to their testaceous covering, and
enabling them to move it. Thus the snail has large
muscular fasciculi running along the abdomen, at-
taching it to the upper turn of the shell, and enabling
the animal to withdraw itself into the cavity. The
bivalves have powerful adductor muscles to close
their shells2. In several of the mollusca nuda there
is a considerable apparatus of cutaneous fibres, by
which a very remarkable shortening of the body
can be produced. A similar and very astonishing
contractile power resides in the gelatinous paren-
chyma of the zoophytes, and animals which inha-
bit corals; in whose structure nothing like muscular
fibres can be distinguished.

Additional Notes to the Twenty-second Chapter.

[Seite 394]

(A) The differences which we discern in the
muscles of the lower extremity between man and
the other mammalia, arise out of that characteristic
feature, which so strikingly distinguishes man from
all other animals: viz. his erect stature. The most
minute investigation of this subject will shew us
that the erect position belongs to man only; and
thereby confirms the elegant observation of the
Roman poet:

Pronaque cum spectent animalia cetera terram,
Os homini sublime dedit; coelumque tueri
Jussit; et erectos ad sidera tollere vultus.

In order to enable any animal to preserve the
erect position, the following conditions are required.
First, That the parts of the body should be so dis-
posed, as to admit of being maintained with ease in
a state of equilibrium; 2dly, That the muscles
should have sufficient power to correct the devia-
tions from this state; 3dly, That the centre of
gravity of the whole body should fall within the
space occupied by the feet; and lastly, That the
feet themselves should have a broad surface resting
firmly on the ground, and should admit of being
[Seite 395] in a manner fixed to the earth. All these circum-
stances are united in the necessary degree in man
only.

The broader the surface included by the feet, the
more securely will the line of gravity rest within
that surface. The feet of man are much broader
than those of any animal, and admit of being sepa-
rated more widely from each other. The sources
of the latter prerogative reside in the superior
breadth of the human pelvis, and in the length and
obliquity of the neck of the femur, which by
throwing the body of the bone outwards, disengage
it from the hip-joint.

The whole tarsus, metatarsus, and toes, rest on
the ground in the human subject, but not in other
animals. The simiae, and the bear, have the end
of the os calcis raised from the surface; while on
the contrary it projects in man, and its prominent
portion has a most important share in supporting
the back of the foot. The exterior margin of the
foot rests chiefly on the ground in the simiae;
which circumstance leaves them a freer use of their
thumb and long toes in seizing the branches of
trees, &c.; and renders the organ so much the less
adapted to support the body on level ground.

The plantaris muscle, instead of terminating in
the os calcis, expands into the plantar fascia in the
simiae; and in other quadrupeds it holds the place
of the flexor brevis or perforatus digitorum pedis,
[Seite 396] passing over the os calcis in such a direction that its
tendon would be compressed, and its action im-
peded if the heel rested on the ground.

The extensors of the ancle joint, and chiefly those,
which from the calf of the leg, are very small in the
mammalia, even in the genus simia. The peculiar
mode of progression of the human subject suffici-
ently accounts for their vastly superior magnitude
in man. By elevating the os calcis they raise the
whole body in the act of progression; and, by ex-
tending the leg on the foot, they counteract that
tendency, which the weight of the body has to bend
the leg in standing.

The thigh is placed in the same line with the
trunk in man; it always forms an angle with the
spine in animals; and this is often even an acute
one. The extensors of the knee are much stronger
in the human subject than in other mammalia, as
their double effect of extending the leg on the
thigh, and of bringing the thigh forwards on the
leg forms a very essential part in the human mode
of progression.

The flexors of the knee are, on the contrary,
stronger in animals; and are inserted so much lower
down in the tibia (even in the simiae), than in the
human subject, that the support of the body on the
hind legs must be very insecure; as the thigh and
leg form an angle, instead of continuing in a straight
line.

[Seite 397]

The gluteus maximus, which is the largest muscle
of the human body, is so small and insignificant in
animals, that it may almost be said not to exist.
This muscle, which forms the great bulk of the hu-
man buttock, extends the pelvis on the thighs in
standing; and, assisted by the other two glutei,
maintains that part in a state of equilibrium on the
lower extremity, which rests on the ground, while
the other is carried forwards, in progression. The
true office of these important muscles does not
therefore consist, as it is usually represented, in the
common anatomical works, in moving the thigh on
the pelvis, but in that of fixing the pelvis on the
thighs, and of maintaining it in the erect position.

Such then are the supports, by which the trunk
of the human body is firmly maintained in the erect
position. The properties of the trunk, which con-
tribute to the same end, do not so immediately be-
long to the present part of the work; but may be
slightly mentioned to complete the view of the sub-
ject. The breadth of the human pelvis affords a
firm basis on which all the superior parts rest
securely; the same part is so narrow in other
animals, that the trunk represents an inverted pyra-
mid; and there must consequently be great diffi-
culty in maintaining it in a state of equilibrium, if it
were possible for the animal to assume the erect po-
sition. In those instances, where the pelvis is
[Seite 398] broader, the other conditions of the upright stature
are absent: the bear, however, forms an exception
to this observation, and consequently admits of being
taught to stand and walk erect, although the posture
is manifestly inconvenient and irksome to the animal.

The perpendicular position of the vertebral co-
lumn under the centre of the basis cranii, and the
direction of the eyes and mouth forwards would be
as inconvenient to man, if he went on all-fours; as
they are well adapted to his erect stature. In the
former case he would not be able to look before
him; and the great weight of the head, with the
comparative weakness of the extensor muscles, and
the want of ligamentum nuchae would render the
elevation of that organ almost impossible.

When quadrupeds endeavour to support them-
selves on the hind extremities, as, for instance, for
the purpose of seizing any objects with the fore-feet,
they rather fit down than assume the erect position.
For they rest on the thighs as well as on the feet,
and this can only be done where the fore-part of
the body is small, as in the simiae, the squirrel, &c.:
in other cases, the animal is obliged also to support
itself by the fore-feet, as in the dog, cat, &c. The
large and strong tail in some instances forms as it
were a third foot, and thereby increases the surface
for supporting the body; as in the kanguroo and the
jerboa.

[Seite 399]

Various gradations may be observed in the mam-
malia, connecting man to those animals which are
strictly quadrupeds. The simiae, which are by no
means calculated for the erect position, are not, on
the other hand, destined like the proper quadrupeds
to go on all-fours. They live in trees, where their
front and hind extremities are both employed in
climbing, &c.

The true quadrupeds have the front of the trunk
supported by the anterior extremities, which are
consequently much larger and stronger than in man;
as the hind-feet of the same animals yield in these
respects to those of the human subject. The chest
is in a manner suspended between the scapulae, and
the serrati magni muscles which support it in this
position are consequently of great bulk and strength.
When viewed together they represent a kind of girth
surrounding the chest.

(B) The pectoralis major, latissimus dorsi, and
teres major, are of vast size in the mole; and enable
the animal to dig its way under ground, and to
throw up the earth.

(C) Birds possess three pectoral muscles, arising
chiefly from their enormous sternum, and acting on
the head of the humerus. The first, or great pectoral,
weighs, of itself, more than all the other muscles of
[Seite 400] the bird together. The keel of the sternum, the
fork, and the last ribs, give origin to it; and it is
inserted in a rough projecting line of the humerus.
By depressing that bone, it produces the strong and
violent motions of the wing, which carry the body
forwards in flying. The middle pectoral lies under
this; and sends its tendon over the junction of the
fork, with the clavicle and scapula, as in a pulley, to
be inserted in the upper part of the humerus; which
bone it elevates. By this contrivance of the pulley,
the elevator of the wing is placed at the under surface
of the body. The third, or lesser pectoral muscle,
has the same effect with the great pectoral, in de-
pressing the wing.

(D) One of the flexor tendons of the toes of
birds, (produced from a muscle which comes from
the pubis) runs in front of the knee; and all these
tendons go behind the heel: hence the flexion of
the knee and heel produces mechanically a bent
state of the toes, which may be seen in the dead
bird; and it is by means of this structure that the
bird is supported, when roosting, without any mus-
cular action.

‘“This circumstance of the flexion of the toes
accompanying that of the other joints of the lower
extremity of birds, was long ago observed by Bo-
relli
, and attributed by him to the connexion,
which the flexors of the toes have with the upper
[Seite 401] parts of the limb, by which they are mechanically
stretched, when the knee is bent. This explanation
has been controverted by Vicq-d’Azyr, and
others, who have referred the effect to the irritabi-
lity of the muscles. The opinion of Borelli appears,
notwithstanding, to be well founded; for not only
the tendon of the accessory flexor passing round the
knee, but the course of the flexor tendons over the
heel, and along the metatarsus, must necessarily
cause the contraction of the toes, when either of these
joints is bent; and if the phenomenon was not pro-
duced on mechanic principles, it would be impossible
for birds to exhibit it during sleep, which they do,
or to prove the effect on the limb of a dead bird,
than which nothing is more easy. The utility of
this contrivance is great in all birds, but particularly
so in the rapacious tribe, which by this means grasp
their prey in the very act of pouncing on it; and it
is still more necessary to those birds which perch or
roost during their sleep, as they could not otherwise
preserve their position, when all their voluntary
powers are suspended.”’

Rees’s Cyclopedia, art. Birds.

[Seite 402]

THE
GENERATIVE FUNCTIONS.

[Seite 403] [Seite 404]

CHAPTER XXIII.*
ON THE MALE ORGANS OF GENERATION.

[Seite 405]

§ 310. In considering the comparative anatomy
of the sexual functions, we must confine ourselves
to those animals, which possess male organs destined
for the purpose of impregnation, and female parts
for that of conception.

To the former belong chiefly the testes, vesi-
culae seminales, prostate and penis. Yet the three
last mentioned parts, and particularly the vesiculae
and prostate are by no means constantly found
even in red-blooded animals.

§ 311. The testes, and sometimes the vesiculae
seminales and prostate vary most remarkably in
their magnitude in such animals, as have a regular
rutting season. They are very diminutive at other
periods of the year; but swell at that particular
time to a comparatively vast magnitude. This
change is particularly observable in the testes of the
mole, sparrow, and frog1.

[Seite 406]

§ 312. It is necessary to mention here, in a
cursory and general manner, the peculiar organs
possessed by the males of some species, for the pur-
pose of holding the female during the act of copu-
lation. Of this kind are, the spur on the hind-feet
of the male ornithorhynchus; the rough black
tubercle formed in the spring season on the thumb
of the common frog; the two members, formed of
bones articulated to each other, near the genitals
of the male torpedo and other cartilaginous fishes2;
the forceps on the abdomen of the male dragon-
fly, &c.

(A) Mammalia.

§ 313. A scrotum, or bag, in which the testes hang
on the outside of the abdominal cavity exists only
in the mammalia; but is not by any means
common to all the genera. It is not found, and
that for very obvious reasons, in the aquatic animals
of this class; nor in the perfect subterranea (those
[Seite 407] which live under ground), as the mole; nor in
such as roll themselves up on the approach of
danger, as the hedgehog. These which may be
called true testiconda (i.e. animals having their
testes concealed) must be distinguished from such,
as have the power of withdrawing these glands
from the abdomen, and retracting them into the
cavity according to circumstances; as the hamster3
(marmota cricetus) and Canadian musk-rat4 (mus
zibethicus
).

In those testiconda, which have the penis much
concealed by the integuments in its unerected
state, as the hare, rabbit, elephant, &c. it is difficult
some times to distinguish the sexes on the first view,
particularly at an early age. (For further particu-
lars respecting the position of the testes, &c. see
note (B) at the end of the chapter.)

§ 314. In several quadrupeds, as the dog,
horse, ram and others, there is a body, composed
of condensed cellular substance, lying according to
the axis of the testicle near the epididymis, and
known by the name of corpus Highmori. This is
not a canal, nor does it possess that artificial struc-
ture which has been been described and delineated
[Seite 408] by several anatomists of the seventeenth century5.
(See note (C).

§ 315. Most species of mammalia, and, with
the exception of the cetacea6, some out of every
other order in the class, possess vesiculae seminales.
They fwell to a vast size in the rutting season in
many animals, as some of the simiae, and most par-
ticularly in the hedgehog7.

Among the species, in which these parts do not
exist, are the dog and cat-kind, the bears, the
opossums, sea-otter, seals, and ornithorhynchus.
(For further particulars on this subject, see note
(D).

[Seite 409]

§ 316. The possession of a prostate (in some
instances simple, but generally divided into two
parts) is peculiar to the mammalia; and seems to
take place in every species of the whole class. In many
animals, at least, where its existence has been de-
nied, as in the goat and ram, considerable glandu-
lar bodies are found, which bear a greater re-
semblance to the prostate, than to Cowper’s
glands8.

§ 317. In many species the penis consists of a
single corpus cavernosum, without any septum. The
pig and the cetacea furnish examples of this struc-
ture; and in the latter animals there are numerous
tendinous layers crossing it9.

In some species, where the act of copulation
requires a longer portion of time, as in the dog,
badger, &c. the corpus spongiosum of the glans,
and of the posterior part of the penis, swells during
the act much more considerably than the rest of
the organ, and thus the male and female are held
together during a sufficient space of time for the
discharge of the seminal fluid10. (See note (E).

[Seite 410]

§ 318. Several species of mammalia, both
among those, which possess no vesiculae seminales,
and thereby require a longer time for completing
the act of copulation, and in such as are not dis-
tinguished by this peculiarity11, possess a peculiar
bone in the penis, generally of a cylindrical form,
but sometimes grooved12. This the case with some
of the simiae, most of the bat-kind, the hamster and
several others of the mouse-kind, the dog, bear,
badger, weasel, seal, walrus, &c13.

§ 319. In most of the male animals of this
class the urethra runs on to the end of the glans,
and forms a common passage for the urine, prostatic
liquor and semen. In some few species, the pas-
sage which conducts the two former fluids, is dis-
tinct from that of the seminal liquor. The bifid
fork-like glans of the opossum14 has three openings,
[Seite 411] one at the point of bifurcation for transmitting
the urine; and two for the seminal fluid at the two
extremities of the glans. The short urethra of
the ornithorhynchus paradoxus opens directly into
the cloaca, and the large penis of the animal serves
merely to conduct the seminal fluid. It divides
into two parts at its extremity, and each of these is
furnished with sharp papillae, which are perforated
for the passage of the semen15. A similar structure
obtains in the ornith. hystrix; where the penis divides
into four glandes16.

§ 320. In some species of the cat-kind the
glans is covered with retroverted papillae, which, as
these animals have no vesiculae seminales, may en-
able the male to hold the female longer in his em-
braces17.

§ 321. Lastly, it deserves to be mentioned,
that in some species of this class, the male penis,
while unerected, is turned backwards; so that the
urine is voided in the male, in the same direction
[Seite 412] as in the female. The hare, lion, and camel, afford
instances of this structure. But the statement
which has been so often repeated since the time of
Aristotle18, that these retromingentia copulate
backwards, is erroneous.

(B) Birds.

§ 322. The testes, which lie near the kidnies, and
the ductus deferentes, are the only male organs
which are constantly found in the whole class19.
(See note (F).

In a very few instances, as in the cock, the last
mentioned canals terminate in a dilated part, which
has been considered analogous to the vesiculae semi-
nales. Instead of a penis, most birds have in the
cloaca two small papillae, on which the seminal ducts
terminate. This is the case in the cock20, turkey,
and pigeon.

Some few species have a simple penis of consider-
able length, which is ordinarily concealed and
retracted within the cloaca; but remains visible
externally for some time after copulation. It forms
[Seite 413] a long worm-shaped tube in the drake1; and con-
stitutes a groove in the ostrich, which is visible when
the animal discharges its urine2.

(C) Amphibia.

§ 323. The kidney, testes, and epididymis, lie
close together in the testudines; but each of the
three organs may be distinguished by its peculiar
colour and structure on the first view. They ap-
pear to have no vesiculae seminales3; I could at
least discover none in a testudo graeca, which I lately
dissected. The penis on the contrary is very large;
and retracted within the cloaca in its ordinary state.
Instead of an urethra, this part contains a groove;
whose margins approach to each other, when the
[Seite 414] part is erected, so as to form a closed canal4. The
glans terminates in an obtuse hook-like point,
somewhat resembling the end of the elephant’s
trunk.

§ 324. Frogs5 have large vesiculae seminales;
and a small papilla in the cloaca, instead of a penis.
Both these parts are wanting in the toad6.

§ 325. Crocodiles have a simple penis; while
the lizards of this country have two; and the
water-newt, which does not copulate, has no
organ of the kind.

§ 326. Serpents have long slender testicles;
no vesiculae seminales; but a double penis, each of
which has a bifid point covered with sharp pa-
pillae7.

(D) Fishes.

§ 327. The male organs of generation possess
[Seite 415] very different structures8 in the different orders of
this class. We shall take two species as examples;
the torpedo for the cartilaginous, and the carp for
the bony fishes.

In the former instance there are manifest testicles,
consisting partly of innumerable glandular and
granular bodies, and partly of a substance like
the soft roe of bony fishes. We find also vasa
deferentia,
and a vesicula seminalis which opens into
the rectum by means of a small papilla9.

The soft roe supplies the place of testes in the
carp10, and most other bony fishes. It forms two
elongated flat viscera of a white colour, and irre-
gular tuberculated surface; placed at the sides of
the intestines and swimming bladder, so that the
left encloses the rectum in a kind of groove.
Through the middle of each soft roe passes a ductus
deferens,
which opens behind into a kind of vesi-
cula seminalis, and this terminates in the clo-
aca11.

(E) Insects.

[Seite 416]

§ 328. The animals of this class exhibit such
numerous varieties of structure in the different
orders, genera, and species12, that we shall be
contented with choosing two of the latter as ex-
amples. These are, the moth of the silk-worm
(bomleyx mori), which is chosen because its genital
organs resemble those of some of the more perfect
red blooded animals; and a species of locust
(gryllus) on account of the external resemblance
between the male and female organs.

In the latter (gryllus verrucivorus) the large
testicles with their convoluted fasciculi of vessels
[Seite 417] bear a very close resemblance to the ovaries, in which
the ova are collected into similar bundles13.

In the moth of the silk-worm we distinguish, be-
sides the testes, long vasa deferentia, even a kind
of vesiculae seminales, and a very considerable penis,
with a hook-shaped glans14.

(F) Vermes.

§ 329. From this class we shall select two in-
stances15. The one is an intestinal worm (ascaris
lumbricoides
), and derives, therefore, some interest
from its connection with nosology. The cuttle-fish,
of the class mollusca, forms the other, and is selected
on account of the remarkable peculiarities in its
male organs.

The ascaris has one testis, occupying nearly
the middle of the animal’s body, and consisting of
[Seite 418] a single vessel convoluted into a long bundle, but
admitting of being unravelled with facility; when
it appears to be about three feet in length. To-
wards the posterior part of the worm it forms a
larger tube, which nearly equals a crow’s quill
in size, and becomes connected to the penis, which
lies concealed near the tail, and is probably pro-
jected at the time of copulation16. (See note
(G).

The male organs of the cuttle-fish (sepialoligo)
have excited particular attention, from the remark-
able, and, indeed, somewhat heightened description
which Turberville Needham17 gave of them,
and which formed the basis of Buffon’s theory of
generation18.

The part, which corresponds to the soft roe of
bony fishes, contains at the spawning season several
hundred small tubular seminal receptacles (about
four lines in length): these are placed in bundles
towards the vas deferens, and are contained in a
thick fluid. These tubes are expelled from the
body in an entire state; when a spiral vessel, which
they contain, together with the semen, as in a
sheath, bursts their thin anterior extremity, from
which the semen escapes and impregnates the spawn
of the female.

Additional Notes to the Twenty-third Chapter.

[Seite 419]

(A) I have inserted the following general view
of the subject of generation from the 5th vol. of
the Léçons d’Anatomie comparée, as it affords a com-
parative statement of the manner, in which that
function is executed in the different classes; al-
though the remarks may be considered by some as
too much of a physiological nature to admit of in-
sertion in a merely anatomical work.

‘“The nature of generation, which is the greatest
mystery in the economy of living bodies, is still in-
volved in impenetrable obscurity. The creation of
a living body, that is, its formation by the union of
particles suddenly brought together, has not
hitherto been proved by any direct observation.
The comparison of this process to that of crystalli-
zation is founded in a false analogy: crystals are
formed of similar particles attracting each other
indifferently, and agglutinated by their surfaces,
which determine the order of their arrangement:
living bodies, on the contrary, consist of numerous
fibres or laminae of heterogeneous composition, and
various figures, each of which has its peculiar situa-
tion in relation to the other fibres and laminae.
Moreover, from the instant in which a living body
can be said to exist, however small it may be, it
possesses all its parts; it does not grow by the addi-
[Seite 420] tion of any new laminae, but by the uniform or
irregular development of parts which existed before
any sensible growth.’

‘“The only circumstance common to all genera-
tion, and consequently the only essential part of the
process, is, that every living body is attached at first
to a larger body of the same species with itself. It con-
stitutes a part of this larger body, and derives nou-
rishment, for a certain time, from its juices. The
subsequent separation constitutes birth; and may
be the simple result of the life of the larger body,
and of the consequent development of the smaller,
without the addition of any occasional action.’

‘“Thus the essence of generation consists in the
appearance of a small organised body in or upon
some part of a larger one; from which it is sepa-
rated at a certain period in order to assume an in-
dependent existence.’

‘“All the processes and organs, which co-operate
in the business of generation in certain classes,
are only accessory to this primary function.’

‘“When the function is thus reduced to its most
simple state, it constitutes the gemmiparous, or gene-
ration by shoots.
In this way the buds of trees are
developed into branches, from which other trees
may be formed. The polypes (hydra) and the
sea anemones (actinia) multiply in this manner;
some worms are propagated by a division of their
body, and must therefore be arranged in the same
[Seite 421] division. This mode of generation requires no dis-
tinction of sex, no copulation, nor any particular
organ.’

‘“Other modes of generation are accomplished
in appropriate organs: the germs appear in a de-
finite situation in the body, and the assistance of
certain operations is required for their further de-
velopment. These operations constitute fecundation,
and suppose the existence of sexual parts; which
may either be separate, or united in the same indi-
vidual.’

‘“The office of the male sex is that of furnishing
the fecundating or seminal fuid: but the manner,
in which that contributes to the development of
the germ, is not yet settled by physiologists. Some,
forming their opinions from the human subject
and the mammalia, where the germs are impercep-
tible before fecundation, suppose that these are
created by the mixture of the male fluid with that
which they suppose to exist in the female; or that
they pre-exist in the male semen, and that the fe-
male only furnishes them with an abode. Others
consult the analogy of the other classes of animals,
and of plants. In several instances, particularly in
the frog, the germ may be clearly recognised in the
ovum, before fecundation: its pre-existence may be
concluded in other cases, from the manner in
which it is connected to the ovum when it first
becomes visible; for it is agreed on all sides that
the ovum exists in the female before fecundation,
[Seite 422] since virgin hens lay eggs, &c. From such consi-
derations these physiologists conclude, that the
germ pre-exists in all females; and that the fecun-
dating liquor is a stimulus which bestows on it an
independent life, by awakening it, in a manner,
from the species of lethargy, in which it would
otherwise have constantly remained.’

‘“The origin of the germs, and the mode of
their existence in the female; whether they are
formed anew by the action of life, or are pre-
existent, and inclosed within each other; or whether
they are disseminated, and require a concourse of
circumstances to bring them into a situation favour-
able for their development; are questions, which,
in the present state of our knowledge, it is utterly
impossible for us to decide. These points have for
a long time been agitated by physiologists; but the
discussion seems now to be abandoned by universal
consent.’

‘“The combination of the sexes, and the mode of
fecundation are subject to great variety. In some
instances they are united in the same individual, and
the animal impregnates itself. The acephalous
mollusca, and the echinus exemplify this structure.
In others, although the sexes are united in each
individual, an act of copulation is required, in
which they both fecundate, and are fecundated.
This is the case with the gasteropodous mollusca,
and several worms. In the remainder of the
[Seite 423] animal kingdom the sexes belong to different indi-
viduals.’

‘“The fecundating liquor is always applied upon,
or about the germs. In many cases the ova are
laid before they are touched by the semen; as in
some fishes of the bony division, and the cephalopo-
dous mollusca. Here, therefore, impregnation is
effected out of the body; as it is also in the frog
and toad. But in the latter instances the male
embraces the female, and discharges his semen in
proportion as she voids the eggs. In most animals
the seminal liquor is introduced into the body of
the female, and the ova are fecundated before they
are discharged. This is the case in the mammalia,
birds, most reptiles, and some fishes; in the herma-
phrodite gasteropodous mollusca, in the crustacea,
and insects. The act by which this is accomplished,
is termed copulation.

‘“In all the last mentioned orders ova may be
discharged without previous copulation, as in the
preceding ones. But they receive no further de-
velopment; nor can they be fecundated when thus
voided.’

‘“The effect of a single copulation varies in its
degree; it usually fecundates one generation only;
but sometimes, as in poultry, several eggs are fe-
cundated; still, however, they only form one gene-
ration.’

‘“In a very few instances one act of copulation
[Seite 424] fecundates several generations, which can propa-
gate their species without the aid of the male. In
the plant-louse (aphis) this has been repeated eight
times; and in some monoculi twelve or fifteen
times.’

‘“When the germ is detached from the ovary,
its mode of existence may be more or less complete.
In most animals it is connected, by means of vessels,
to an organised mass, the absorption of which nou-
rishes and developes it until the period of its birth.
It derives nothing, therefore, from the body of the
mother, from which it is separated by coverings
varying in number and solidity. The germ, to-
gether with its mass of nourishment, and the sur-
rounding membranes, constitutes an egg, or ovum;
and the animals which produce their young in this
state, are denominated oviparous.

‘“In most of these the germ contained in the
egg is not developed until that part has quitted the
body of the mother, or has been laid; whether it
be necessary that it should be afterwards fecun-
dated, as in many fishes; or require only the ap-
plication of artificial heat for its incubation, as in
birds; or that the natural heat of the climate is
sufficient, as in reptiles, insects, &c. These are
strictly oviparous animals.’

‘“The ovum, after being fecundated, and de-
tached from the ovarium, remains in some animals
within the body of the mother, until the contained
[Seite 425] germ be developed and hatched. These are false
viviparous
animals; or ovo-viviparous. The viper,
and some fishes afford instances of this process.’

‘“Mammalia alone are truly viviparous animals.
Their germ possesses no provision of nourishment,
but grows by what it derives from the juices of the
mother. For this purpose it is attached to the in-
ternal surface of the uterus, and sometimes, by
accident, to other parts, by a kind of root, or infi-
nite ramification of vessels, called a placenta. It is
not, therefore, completely separated from the
mother by its coverings. It does not come into
the world until it can enjoy an independent organic
existence. The mammalia cannot, therefore, be
said to possess an ovum in the sense which we have
assigned to that term.’

‘“From the above view of the subject, genera-
tion may be said to consist of four functions, differ-
ing in their importance, and in the number of ani-
mals, to which they belong.’

‘“1st, The production of the germ, which is a
constant circumstance; 2dly, fecundation, which be-
longs only to the sexual generation; 3dly, copulation,
which is confined to those sexual generations, in
which fecundation is accomplished within the body:’

‘“Lastly, uterogestation, which belongs exclu-
sively to viviparous generation.”’ Léçon 29, pag. 2,
and seq.

[Seite 426]

(B) A scrotum exists in all the quadrumana,
and in most of the carnivora; in animals of the
opossum kind, which have it in front of the pelvis;
in the hare, and gerboa; in most of the ruminating
genera, and in the solidungula.

The testes are placed under the skin of the peri-
neum in the pachydermata and the civet; or under
that of the groin, as in the camel and otter. They
pass from the abdomen into one or the other of
these situations, particularly at the rutting season,
in the bats, the mole, shrew, and hedge-hog; and
in several rodentia, as the rat, guinea-pig, porcu-
pine, beaver, squirrel, &c. They remain constant-
ly in the abdomen in the ornithorhynchus para-
doxus, and hystrix, in the elephant, hyrax, the am-
phibious mammalia, and the cetacea.

The tunica vaginalis exists constantly in the
mammalia. As the horizontal position of the
body obviates the danger of herniae, the cavity of
this covering always communicates by means of a
narrow canal with the abdomen, in such animals as
have the testes remaining constantly in the scrotum.
Where these glands occasionally pass out of the abdo-
men, and return again, the communication is very
broad and free.

(C) The seminal tubes are collected in some
animals into large fasciculi; as in the baboons,
[Seite 427] most of the large carnivora, the wild boar, and the
rhinoceros. It is the union of the septa, which
divide these fasciculi, that constitutes the corpus
Highmori. In most of the rodentia, and particu-
larly in the rat, these tubes are large and parallel,
and very easily separable.

The vasa deferentia are usually enlarged in size,
and assume a cellular structure for some short dis-
tance previous to their termination. The structure
of this part is the most remarkable in the horse;
where ‘“the vas deferens, in passing over the blad-
der, enlarges to the size of the human thumb; this
amplification extends from its entrance into the
urethra to the distance of five or six inches from
that point, where it again becomes of its ordinary
diameter.’

‘“The inside of this enlargement is composed of
cells, and somewhat resembles in construction the
cells of the corpus cavernosum penis, passing in a
transverse direction across the tube. In the centre
of this enlargement passes the small canal of the
vas deferens; each cell communicates by one, two,
or more small pores with the canal of the vas defe-
rens, and the cells diminish as they approach the
neck of the bladder, till they are lost in a smooth
passage entering the urethra.’

‘“What the purpose of this structure is, does not
appear; it must retard the passage of the semen,
and probably adds some fluid to it, secreted from
[Seite 428] the cells themselves.”’ Mr. Clark in Rees’s
Cyclopaedia, art. Anatomy of the Horse.

The cells of this part contain a thick white fluid,
which flows out in abundance on compression.

An analogous structure is met with in the ram.

(D) The following animals have no vesiculae
seminales according to Cuvier: the plantigrada,
except the racoon and hedge-hog; all the carni-
vora, and marsupial animals; the ruminantia, the
seals, the cetacea, and the two species of orni-
thorhynchus. Their existence or absence does
not seem to follow any general law.

Their form and structure vary almost infinitely
in the different mammalia, where they often termi-
nate in the urethra by a separate opening from that
of the vas deferens. This circumstance, together
with the fact of their containing generally a fluid
of different appearance and properties from those
of the semen, and the glandular structure which
their coats possess in many instances, militates
strongly against the opinion, which considers these
vesicles as reservoirs of the semen, and inclines us
to suppose with Mr. Hunter, that they add a pe-
culiar secretion of their own to the fluid which
comes from the testes.

See Mr. Hunter’s remarks on the vesiculae
seminales, in his Observations on certain Parts of the
Animal Economy,
p. 27. and seq.

[Seite 429]

In the hedge-hog these parts are of a vast size,
much exceeding the volume of the testes. They
form four or five bodies on each side, consisting of
a small and infinitely convoluted tube, and open
separately into the urethra. The rodentia are
generally distinguished by the great size of their
vesicles. These parts in the guinea-pig are long,
uniform, cylindrical cavities, containing generally a
firm cheesy matter. In the boar they are very large,
and of a lobulated structure; a common excretory
duct receives the branches from the lobes. In the
horse, they form two large and simple membranous
bags, opening near the vasa deferentia, but sepa-
rately.

(E) In the quadrumana and bats the penis
hangs loose from the pubis as in man. In most
of the other mammalia it is contained in a sheath of
the integuments, which extends nearly to the navel,
This sheath has an adductor and a retractor muscle.
The penis is generally folded when drawn within
the sheath, on account of its length. In some ani-
mals it turns back, when it has reached the front
of the pubis, and passes out near the anus; this is
the case with the guinea-pig, marmot, and squirrel.
It goes directly backwards from the beginning in
the hare, rat, dormouse and opossum, where the
prepuce is found close to the anus.

The corpora cavernosa form a cylindrical ring
[Seite 430] in the kanguroo; and the urethra passes in the
centre.

Mr. B. Clark has given us the following inter-
esting observations on the penis of the horse, in his
description of the anatomy of that animal in the
2nd vol. of Rees’s Cyclopaedia, art. Anatomy
of the Horse
.

‘“We have remarked that the penis of the
horse possesses a voluntary power of erection, not
known to the human, nor perhaps to most other
animals. This power is exerted on making water,
and though the erection is not very considerable,
it is yet sufficient to bring the penis from its sheath,
which is effected apparently by its increased gravity
from blood accumulating in the cavernous cells of
this part. After staleing this semi-erection of the
penis subsides, and it is again retracted within the
sheath. This operation, though occurring daily to
the fight of every one, has not, it is apprehended,
been noticed by any veterinary writer.’

‘“The urethra of the horse is muscular from
one extremity to the other, being formed on the
outside of strong transverse fleshy fibres, and sup-
ported by a strong ligament.’

‘“In the glans of the penis, immediately over the
opening of the urethra, externally, there is a large
cell or cavity, smooth on the inside, and lined with
a membrane which secretes a brown unctuous sub-
stance for the lubrication of the penis, and defend-
[Seite 431] ing it from the corrosive effects of the urine;
another cell of a similar description with the former
is observable, on the side of the urethra, and near-
ly surrounding it; it is separated from the former
by a membranous partition.’

‘“The apparently unctuous secretion above de-
scribed is miscible with water; it burns, however,
in the fire like an oily substance, and is not soluble
in spirits of wine or nitrous acid, nor does it dry on
exposure to the air during several weeks.’

‘“There is nothing resembling a frenum to the
penis of the horse.’

‘“The cavernous body has no longitudinal
septum.’

‘“Another singularity in the genital parts of
this animal is, that there is an immense congeries of
veins, lying on the back of the penis, which are
filled during copulation, forming an elevation
nearly as large as the penis itself; these veins
communicate with both the cavernous and spon-
gious bodies.”’

(F) The testes of birds consist of a congeries
of seminal tubes analogous to those of the mam-
malia.

(G) Dr. Hooper states that he has never
found any distinction of sex in these worms; but
that they all possess the parts described as belonging
to the female.

[Seite 432]

See the account compiled by him in the Mem.
of the Lond. Med. Soc.
vol. 5, p. 237. Yet Dr.
Baillie has given a figure of the male worm,
similar to that of Tyson; but it is copied from
Werner. Fascic. 4, pl. 9, fig. 2 and 4. The
representation of Cuvier agrees with that of Dr.
Hooper. Léçons d’Anat. comp. tom. 5, p. 187.

CHAPTER XXIV.
ON THE FEMALE ORGANS OF GENERATION.

[Seite 433]

§ 330. An ovarium* is the most essential and
universal of all the female parts of generation.
In addition to this, those animals which breathe by
means of lungs, as well as some fishes, and several
white-blooded animals, have also oviducts, (Fallo-
pian tubes, &c.) or canals leading from the ovarium
to the uterus: and lastly, those, at least, which are
impregnated by a real copulation, possess a vagina,
or canal connecting the uterus to the external or-
gans of generation.

In birds, all the parts, which we have just men-
tioned, are single. Some cartilaginous fishes have
two oviducts; beginning, however, by a common
opening, and terminating in a simple uterus. The
human female, as well as that of many other mam-
malia, has two ovaria, with an oviduct belonging to
each; a simple uterus, and vagina. The females of
this class, in several other instances, possess an ute-
rus bicornis:
and in some cases the generative or-
[Seite 434] gans are double throughout; that is, there are two
uteri, and, at least for some extent, a double va-
gina.

(A) Mammalia.

§ 331. Of the external female sexual organs
in this class, the clitoris is found most universally
and invariably1; for it exists even in the whales2,
and probably is wanting in no other instance than
the ornithorynchus3.

As this organ, in its general structure, bears con-
siderable resemblance to the male penis, it contains
a small bone in several species of mammalia, as the
marmota citillus, the racoon (ursus lotor), the lioness,
the sea-otter, &c. In the opossum it possesses a bi-
fid glans, like that of the penis. The analogy be-
tween the two organs is carried so far in the lori
(lemur tardigradus), that the urethra runs through
[Seite 435] the organ, and terminates on its anterior extremity4.
In the rat, the domestic mouse, the hamster, &c.
the clitoris and the orifice of the urethra are placed
at some distance from the vagina, and in front of
that part. This structure has sometimes been
mistaken for a preternatural hermaphrodite for-
mation5. (See note (B).

§ 332. A true hymen, or one at least, which in
form and situation resembles that of the human
subject, has been observed in no other animal. The
well-known membranous valve, covering the ori-
fice of the meatus urinarius in the vagina of the
mare, can by no means be considered as a hy-
men6 (See note (C).

[Seite 436]

§ 333. The vagina of quadrupeds is distin-
guished from that of the human subject by two
chief characters: its direction, and the structure of
its internal surface. In consequence of the form and
position of the pelvis, this canal lies in the same axis
with the uterus, or at least with the neck of that
organ. The glandular membrane, which consti-
tutes its internal coat, forms none of those extremely
elegant transverse plaits, which distinguish it in the
human female, but is merely folded longitudinally.
If transverse folds exist in any instance, they are
either confined to the immediate neighbourhood of
the external opening, as in the mare; or, if they
extend farther, as in the simiae, they do not possess
that regular arrangement, or beautiful formation,
which are displayed in the human female7.

[Seite 437]

§ 334. The structure and form of the uterus
vary very considerably in this class. In no instance
does it possess that thickness, nor has its parenchyma
that density and toughness, which are observed in
the human female8. Of those which I have dis-
sected, the simia sylvanus had comparatively the
firmest uterus. The two-toed ant-eater came the
next in order in this respect. But in the greater
number of mammalia, this organ is thin in its
coats, resembling an intestine in appearance, and
provided with a true muscular covering.

§ 335. The variations in form of the impreg-
nated uterus may be reduced to the following
heads:

1. The simple uterus without horns (uterus sim-
plex
), which is generally of a pyramidal or oval
figure. This is exemplified in those animals, where
we have stated that it possesses thick coats. Its
circumference in some simiae presents a more trian-
gular form than in the woman: and towards the
upper part, in the neighbourhood of the fallopian
[Seite 438] tubes, there is an obscure division into two blind
sacs9, (as in the gibbon, or long-armed ape): this
distinction is more strongly expressed in the lori,
(lemur tardigradus), so as to form a manifest ap-
proach to the uterus bicornis10.

2. A simple uterus with straight or convoluted
horns (uterus bicornis). They are straight in the
bitch11, in the bats of this country, in the sea-otter,
seal, &c.12: somewhat convoluted in the cetacea13,
mare14, and hedge-hog, and still more tortuous in
the bisulca15.

3. A double uterus, having the appearance of
two horns, which open separately into the vagina:
this is seen in the hare16 and rabbit17, (uterus du-
plex
).

4. A double uterus, with extraordinary lateral
[Seite 439] convolutions, is met with in the opossum and kan-
guroo18, (uterus anfructuosus). (See note (D).

§ 336. These various forms undergo different
changes in the pregnant state.

The alteration in the simple uterus is, on the
whole, analogous to that which occurs in the hu-
man female.

The pregnant uterus bicornis suffers a different
change in those animals, which bear only one at a
time, from that which it undergoes in the multi-
para.
The fetus of the mare is confined in its
situation to the proper uterus19. In the cow it ex-
tends at the same time into one of the horns, which
is enlarged for its reception20. In those, on the
contrary, which bring forth many young at once,
as also in the double uterus of the hare and rabbit,
both cornua are divided by contracted portions
into a number of pouches corresponding to that of
the young; and where those horns are straight
in the unimpregnated state, as in the bitch, they
become convoluted1.

[Seite 440]

The uterus of the opossum and kanguroo suffers
the least change from its usual appearance in the
impregnated state. For these strange animals bring
their young into the world so disproportionately
small, that they appear like early abortions. (See
note (E).

§ 337. The Fallopian tubes are convoluted upon
each other in a kind of knob in some instances, as
the simia sylvanus, and still more remarkably in the
opossum. The fimbriae are sometimes shaped like a
funnel, as in the rabbit.

§ 338. The ovaria are generally of an oval
form, and have the ovula Graafiana buried in their
parenchyma. These vesicles, however, project ex-
ternally in some cases, as in the pig; where the
ovaries appear tuberculated on the surface2. In the
hedge-hog they are quite loose and separate, so that
the ovary resembles a bunch of grapes, and thereby
approaches to the structure of the bird.

The number of vesicles appears to accord on the
whole with that of the young, which a mother is
capable of producing during her life3. And the
[Seite 441] corpora lutea, which have received this name from
their colour in the ovaries of the cow, are probably
never found in the quadruped, except after impreg-
nation4.

(B) Birds.

§ 339. The female organs of generation in this
class may be most conveniently arranged under three
divisions: The external parts, including the cloaca;
[Seite 442] the tubus genitalis (oviduct) resembling an intestine;
and lastly, the ovarium, which is almost entirely
separate from the latter part.

As the general structure of these parts is very
uniform in all birds, we may take as an example, the
most familiarly known species, the hen5.

§ 340. The external opening of the genitals
consists of a transverse slit behind the ossa pubis,
which do not form a symphysis: this is larger in the
hen than in the cock; and its smaller anterior la-
bium is covered by the larger posterior one (vela-
brum
).

This slit leads to the cloaca, In which several
organs open, (§ 114). These are the rectum;
the two ureters on the prominent margin of that
part; the vagina on the left; behind which, and
on the upper part of the cloaca, there is the bursa
Fabricii
6.

[Seite 443]

§ 341. In the tubus genitalis, which consider-
ably resembles an intestine, and is really on the
whole very uniform in its appearance, we may,
however, distinguish three parts. The vagina; the
proper uterus; and the oviductus: the latter part
terminates in the infundibulum, which is very diffe-
rent in its structure and appearance.

[Seite 444]

The vagina is about one inch and a half long,
and very extensile: it follows a tortuous course.

The uterus is about the same length, but larger,
and thicker in its parietes; and folded internally.
(See note (F).

The oviductus (in French la portiére) appears
like a continuation of the last mentioned part: it is
about one foot and a half long, convoluted like an
intestine, and, though slightly contracted at inter-
vals, on the whole conical, so that it decreases in
diameter to the infundibulum. Its internal coat is
covered with innumerable papillae, which secrete
the white of the egg; and the whole tube is con-
nected above to the spine by a kind of mesentery
(mesometrium or meseraeon uteri).

It opens by its small end into the infundibulum,
which is an expanded part, analogous to the sim-
briated extremity of the Fallopian tube, for receiving
the yolk from the ovarium. This infundibulum is
formed of a delicate membrane, with a very ele-
gantly folded margin; which is connected behind
to the uterus by means of a round tendinous
cord.

§ 342. The ovarium, resembling in its appear-
ance a bunch of grapes, lies under the liver, and
contains in a young laying hen about five hundred
yolks, varying in size from a pin’s head, to their
perfect magnitude: the largest always occupy the
[Seite 445] external circumference of the part. Each yolk is
inclosed in a membrane (calyx) which is joined
to the ovarium by means of a short stalk or pedicle
(petiolus). A white shining line forms on the
calyx, when the yolk has attained its complete
magnitude. The membrane bursting in this part,
the contained yolk escapes, and is taken up by the
infundibulum in a manner, which we cannot easily
conceive7. It then passes along the oviduct, and
acquires in its passage the white and shell. The calyx
on the contrary remains connected to the ovarium;
but it contracts and diminishes in size, so that in
old hens, which have done laying, the whole in-
ternal organs of generation nearly disappear.

(C) Amphibia.

[Seite 446]

§ 343. The tortoise has a manifest clitoris, lying
in the cloaca. The uterus, oviduct and ovarium
have on the whole much analogy with those of
birds; but all these parts are double, and have
two openings into the cloaca8. The two uteri
are thick and fleshy, while the oviducts are thin and
delicate.

§ 344. The frogs of this country have a large
uterus divided by an internal partition into two
cavities, from which two long convoluted oviducts
arise, and terminate by open orifices at the sides of
the heart. The ovaria lie under the liver, so that
it is difficult to conceive how the ova get into the
above mentioned openings. The uterus opens into
the cloaca9.

The toads have not the large uterus; but their
oviducts terminate by a common tube in the
cloaca10.

§ 345. The lizards of this country have on
[Seite 447] the whole a similar structure to that of the last men-
tioned animals. Their oviducts are larger, but
shorter, and the ovaria contain fewer ova.

§ 346. Female serpents have double external
openings of the genitals for the reception of the
double organs of the male (see § 346). The ovi-
ducts are long and much convoluted. The ovaria
resemble rows of beads, composed of yellow ve-
sicles.

(D) Fishes.

§ 347. We shall take the torpedo and the carp
as examples of the two chief divisions of the class,
as we did in speaking of the male organs11.

In the former fish12 there are two uteri, communi-
cating with the cloaca by means of a common
vagina. The oviducts form one infundibulum,
which receives the ova as they successively arrive at
maturity. These are very large in comparison with
those of the bony fishes. The yolk, in its passage
through the oviduct, acquires its albumen, and
shell. The latter is of a horny consistence, and is
[Seite 448] known by the name of the sea-mouse13. It has an
elongated quadrangular figure, and its four corners
are curved and pointed in the skate, while they
form horny plaited eminences in the sharks14.
The secretion of the albumen, and the formation
of the shell are performed by the papillous inter-
nal surface of the duct; and chiefly by two glan-
dular swellings which appear towards its anterior
extremity in the summer months, while the eggs
are being laid15.

The structure is much more simple in the carp,
and probably also in the other oviparous bony fishes.
The two roes occupy the same position as the soft
roe of the male does (§ 327). They are placed at
the side of the intestines, liver, and swimming
bladder, as far as the anus. They consist of a deli-
cate membrane inclosing the ova, which are all of
one size, and extremely numerous (more than
200,000 in the carp); and terminate by a common
opening behind the anus16. (See note (G).

(E) Insects.

[Seite 449]

§ 348. We shall here notice the two species
only, which were mentioned in the former chap-
ter17.

Each of the large ovaria of the gryllus verruci
vorus
contains about fifty ova disposed in bundles.
The two organs are connected together at their
posterior extremities, and open between the two
sheaths of a part by which they are discharged from
the body18.

In the silkworm moth19 on the contrary, the
ovarium resembles four rows of pearls: each row
contains about sixty ova, which are laid from the
end of the abdomen after passing through a short
duct, which has, however, connected with it several
vesicular processes of uncertain use.

(F) Vermes.

§ 349. We shall describe here the female ge-
nitals of those two animals only, whose male organs
were noticed in the preceding chapter20.

[Seite 450]

The opening of the genitals of the female round-
worm (ascaris lumbricoides) is situated near the
middle of the body, and leads to a short canal,
which divides into two tubes, These gradually con-
tract into two slender threadlike oviducts; which
are very long and variously convoluted1. It happens
occasionally that the integuments of the worm
burst and some turns of the duct protrude: these
have been mistaken for young worms, and have
given rise to the erroneous notion that the animal
is viviparous. (See note (H).

The structure of the parts is very simple in the
cuttle-fish. There are two ovaria, containing ova
of various sizes; and a common tube leading to the
anus2. (For an account of the organs of genera-
tion in some others of the lower classes, see note
(K).

Additional Notes to the Twenty-fourth Chapter.

[Seite 451]

(A) Ovaria are found in the females of all
animals where the male possesses testicles: but their
structure is in general more simple than that of the
latter glands, particularly in the first class. These
bodies were formerly called the female testicles;
but the term ovary is much preferable, as it denotes
the function which the parts perform in the ani-
mal economy. For, if the office of these bodies
be at all dubious, when their structure is considered
in man and most of the mammalia; their organi-
zation is so evident in the other classes, that no
doubt can be entertained respecting their physi-
ology. It is manifest in all these, that the ovaria
serve for the growth and preservation of the germs
or ova, which exist in these, bodies, completely
formed before the act of copulation. Analogy
leads us to conclude that these bodies have the same
office in the mammalia; and thus our explanation
and illustration of this most interesting part of
physiology are entirely derived from researches in
comparative anatomy.

(B) In consequence of the horizontal position
of the body of quadrupeds, the clitoris is at the
under margin of the orifice of the vagina, instead
of the upper one, as in women.

[Seite 452]

It is much larger in the simiae than in women.
The Lemur (macauco), the carnivora, and most of
the rodentia have it also very large.

None of the mammalia possess nymphae; and
there is general merely a thin border of the integu-
ments instead of labia pudendi.

(C) Cuvier considers the opening of the urethra
as forming the distinction in quadrupeds between
the vulva and the vagina; now this aperture is
situated in many animals at a considerable distance
within the external opening of the genitals.

There is a contracted circle in this situation in
the otter, dog, cat, and ruminating animals, which
he considers as analogous to the hymen. He men-
tions also the existence of a considerable fold in the
bear and hyena, in this situation; and that he has
found a manifest hymen in the hyrax. According
to the same author, the mare and ass, and some of
the simiae have an analogous structure. Hence,
he concludes, that the hymen is not a part exclu-
sively peculiar to the human species. Léçons
d’Anat. comp.
tom. 5, p. 128, 133. It appears,
however, clearly from his own descriptions that the
parts in the above-mentioned animals only bear a
remote resemblance to the human hymen.

(D) As the process of generation in these
singular animals deviates very considerably, in some
[Seite 453] of its parts, from the same function as observed in
the other mammalia, a considerable difference is
found in the generative organs: of which, as the
subject is a very interesting one, I shall present the
reader with a more detailed description, from the
paper of Mr. Home, in the Philosophical Transac-
tions for 1795.

‘“The vagina (of the kanguroo) is about an inch
and a half in length, beyond which it is divided
into two separate canals, and on the ridge, which
lies between them, opens the meatus urinarius.’

‘“These two canals are extremely narrow for
about a quarter of an inch in length, and their
coats at this part very thick, but afterwards
they become more dilated; they diverge in
their course, and pass upwards for nearly four
inches in length; they then bend towards each
other, so as to terminate laterally in the two angles
of the fundus of the uterus, of which they appear
to be an uniform continuation.’

‘“The uterus itself is extremely thin and mem-
branous, and its coats infundibular in its shape,
and situated in the middle space between these
canals; it is largest at its fundus, and becomes
smaller and smaller towards the meatus urinarius,
where it terminates; the uterus at that part in the
virgin state being impervious.’

‘“The same internal membrane appears to be
continued over the inner surface of the uterus and
[Seite 454] lateral canals; it is thrown into several folds, form-
ing longitudinal projecting ridges; one of these
constitutes a middle line, extending the whole
length of the uterus, and dividing it into two equal
parts.’

‘“The ovaria, as well as the simbriae, both in
appearance and situation, resemble those of other
quadrupeds; the fallopian tubes follow nearly the
same course to the uterus, but a little way before
they reach it they dilate considerably, forming an
oval cavity; the coats of this part are also much
thicker than those of the rest of the canal, and they
are supplied with an unusual number of blood-vessels,
giving these cavities a glandular appearance. The fallo-
pian tubes after having formed these oval enlargements
contract again, and pass perpendicularly through
the coats of the uterus at its fundus, and terminate
in two projecting orifices, one on each side of the
ridge formed by a fold of the internal membrane.’

‘“In the impregnated state, the uterus, and two
lateral canals have their cavities very much in-
creased in size; but that of the uterus is the most
enlarged: the communication between these canals
and the vagina is completely cut off, by the con-
stricted parts close to the vagina being filled with a
thick inspissated mucus; and in this state of the
parts there is an orifice very distinctly to be seen,
close to the meatus urinarius, large enough to
admit a hog’s bristle, leading directly into the ute-
[Seite 455] rus, where in the virgin state no such passage could
be observed.’

‘“Immediately after parturition, the parts are
nearly brought back into their original state: the
only circumstance deserving of notice is, that the
opening leading directly from the uterus to the
vagina, which is not met with in the virgin state,
after being enlarged by the passage of the foetus,
forms a projecting orifice, and almost wholly con-
ceals the meatus urinarius.’

‘“Were we to consider the uterus and its ap-
pendages in the unimpregnated state, the two lateral
canals would appear to be the proper vagina, parti-
cularly as they begin at the meatus urinarius, which
is commonly placed at the entrance of the proper,
or true vagina, and receive the penis in coition,
the end of which is pointed to fit it for that pur-
pose; in some species of the opossum the male
has a double glans, each of them pointed, and
diverging from the other, so as to enter both
canals. But when we find these canals in the im-
pregnated state, forming with the uterus one
general reservoir of nourishment for the foetus, and
all communication during that period between
them and the vagina cut off, we consider them
more immediately as appendages to the uterus
than the vagina.”’

In the opossum (didelphis marsupialis), the
vagina divides, as it approaches the uterus, into
[Seite 456] two tubes: and the meatus urinarius opens at the
point of division. From each tube a canal com-
mences, which runs outwards, and then returns
in the same course to open into a middle cavity;
from which the cornua uteri arise. The changes
which these parts undergo in the impregnated state
have not hitherto been ascertained.

(E) The passage of the foetus, in the opossum
tribe and the kanguroo, from the cavity of the
uterus into the false belly, where it adheres by its
mouth to the nipple, presents one of the most sin-
gular and interesting phenomena in the whole
circle of comparative anatomy. Physiologists have
not yet ascertained, whether the embryo possesses,
at any period, a connection with the uterus similar
to that which is observed in the other mammalia:
but it appears very probable, that the processes,
which follow the passage of the ovum from the
ovarium, are entirely different in these animals, from
those which take place in the other mammalia.
Neither has the precise period, at which the foetus
enters the false belly, been hitherto shewn.

The following statement of the subject, as far as
it is at present known, is derived from Mr. Home’s
paper.

The uterus and lateral canals, in their pregnant
state, are distended with a very adhesive jelly of a
[Seite 457] bluish white colour; which also fills the oval en-
largements of the fallopian tubes.

‘“In the cavity of the uterus, says Mr. Home,
I detected a substance, which appeared organized;
it was enveloped in the gelatinous matter, and so
small as to make it difficult to form a judgment
respecting it; but when compared with the foetus
after it becomes attached to the nipple, it so
exactly resembled the backbone with the poste-
rior part of the skull, that it is readily recognized to
be the same parts in an earlier stage of their form-
ation.”’

This substance is represented in plate 20, fig. 2;
but the engraving does not, in my opinion, possess
the slightest similitude to the parts mentioned by
Mr. Home.

The size of the foetus at the time it leaves the
uterus is not yet ascertained. The smallest, which
has been hitherto found in the false belly, weighed
twenty-one grains; and was less than an inch in
length. In another instance it was ‘“thirty-one
grains in weight, from a mother of fifty-six pounds.
In this instance the nipple was so short a way in the
mouth, that it readily dropped out, we must there-
fore conclude that it had been very recently attached
to it.’

‘“The foetus at this period had no navel string,
nor any remains of there ever having been one; it
could not be said to be perfectly formed, but those
[Seite 458] parts which fit it to lay hold of the nipple were
more so than the rest of the body. The mouth was
a round hole, just enough to receive the point
of the nipple; the two fore-paws, when com-
pared to the rest of the body, were large and strong,
the little claws extremely distinct; while the hind-
legs, which are afterwards to be so very large, were
both shorter and smaller than the fore ones.”’

‘“The mode in which the young kanguroo passes
from the uterus into the false belly, has been matter
of much speculation; and it has even been sup-
posed that there was an internal communication
between these cavities; but after the most diligent
search, I think I may venture to assert that there is
no such passage. This idea took its rise from their
being no visible opening between the uterus and
vagina, in the unimpregnated state; but such an
opening being very apparent, both during preg-
nancy, and after parturition, overturns this hypo-
thesis; for we cannot suppose that the foetus, when
it has reached the vagina, can pass out in any other
way than through the external part.”’ This passage
will be facilitated by the power which the animal
possesses of drawing down the false belly to the
vulva, which has naturally a considerable projec-
tion.

(F) In speaking of the uterus and vagina of
birds, the author does not sufficiently keep up the
[Seite 459] distinction which ought to be observed between an
uterus and an oviduct.

The germ, or ovum, passes from the ovarium
through a canal, which either conveys it out of the
body, (as in the case of the egg) or transmits it into
another organ. The latter is a cavity, admitting of
enlargement, and having the germ attached to its
parietes by means of vessels, which nourish and pre-
serve it, until it has acquired a certain development.

The first mentioned organs are found in all the
four classes of vertebral animals: they are called
fallopian tubes in the mammalia; and oviducts in the
three other classes. The latter belongs to the mam-
malia only, and is their uterus. We find, however,
that the author speaks of the uterus of other classes:
the difference in the office of the parts is so striking
that they should on no account be confounded to-
gether.

(G) The ovaria of fishes generally contain a
very large number of ova, so as to account to us
satisfactorily for the astonishing multitudes in which
some species are formed. In a perch weighing one
pound two ounces, there were 69, 216 ova in the
ovarium: in a mackarel of one pound three ounces,
129, 200: in a carp of eighteen inches Petit found
342, 144: and in a sturgeon of one hundred and
sixty pounds, there was the enormous number of
1, 467, 500.

[Seite 460]

(H) The genital tubes of the ascaris contain a
milky fluid, which, when examined by the micro-
scope, is found to contain numerous ova.

The ascaris vernicularis possesses a genital appa-
ratus of the same appearance with that of the lum-
bricoides.
Dr. Hooper in Trans. of the Lond. Med.
Soc.

(I) The ova of the cuttle-fish, when discharged
from the body, are connected into bunches, exactly
resembling grapes, by a tenacious and ductile sub-
stance. The similarity is so striking as to have
given rise to the term of sea-grapes, which is applied
to them in common language. In the sepia octopus
and loligo (calmar) they form small masses.

(K) Most of the gasteropodous mollusca are
true hermaphrodites, and have the male and female
organs of generation united in the same indi-
vidual: but they copulate, so that each fecun-
dates, and is fecundated. The common slug (li-
max
) and snail (helix) afford the most familiar
examples of this structure. They possess an ova-
rium, oviduct, testis, vas deferens, and penis. The
oviduct and vas deferens open into a cavity situated
under the right superior horn; and the penis is
contained in the same cavity. The latter part en-
ters the oviduct of the other animal at the time of
copulation.

[Seite 461]

The snail has, in addition to these organs, a very
singular one, the use of which is quite obscure. It
consists of a cavity with an eminence at bottom;
from which a sharp pointed, thin, calcareous body
proceeds. This can be thrust forth from the ca-
vity, and is employed by the snails to prick each
other before the act of copulation.

In the acephalous mollusca, such as the oyster,
muscle, &c. there is no discernible organ of gene-
ration, except an ovarium, which varies in size and
colour at different periods of gestation.

The same observation holds good also of the aste-
rias
(star-fish) and echinus (sea-urchin). In both
these genera the ovaria consist of several distinct
masses of ova.

The process of generation in the zoophytes re-
sembles the growth of buds and branches in trees
and therefore these animals contain no generative
organs, nor have any distinction of sex. This is the
case in the polype (hydra) and the sea anemone
(actinia); where the young shoot out from any
part of the surface of the parent. If these animals
are cut in two, the divided portions will form per-
fect animals.

CHAPTER XXV.
ON THE FOETUS, OF THE MAMMALIA, AND THE
ORGANS WITH WHICH IT IS CONNECTED.1

[Seite 462]

§ 350. The first parts which can be discerned
in the uterus after impregnation, are the mem-
branes (involucra) of the ovum; in which the
embryo itself becomes visible after a certain period.
By means of the navel-string the foetus is connected
to these membranes, and consequently to the uterus
of the mother; from which its nourishment is de-
rived until the time of birth. It will, therefore, be
the natural method to pass from the description
of the uterus, to that of the membranes, and other
parts of the after birth; and to consider in the
last place whatever may be worthy of remark con-
cerning the embryo itself.

§ 351. The mode of connection of the preg-
nant uterus with the membranes of the ovum,
and thereby with the embryo itself, displays three
chief differences in the various mammalia.

[Seite 463]

Either the whole external surface of the ovum
adheres to the cavity of the uterus; or the con-
nection is effected by means of a simple placenta;
or by more numerous small placentae (coty-
ledons
).

§ 352. The first kind of structure is observed
in the sow2; and is still more manifest in the mare.
In the latter case, the external membrane of the
ovum, the chorion, may be said to form a bag-like
placenta. Numerous and large branches of the um-
bilical vessels ramify through it, particularly in the
latter half of the period of pregnancy; and its ex-
ternal surface is covered with innumerable floccu-
lent papillae, which connect it to the inside of the
uterus3.

§ 353. In those animals of this class, where
the embryo is nourished by means of a placenta,
remarkable varieties occur in the several species;
sometimes in the form and successive changes of the
part; sometimes in the structure of the organ as
being more simple or complicated.

In most of the digitated mammalia, as well as in
the quadrumana, the placenta has a roundish
[Seite 464] form4; yet it consists sometimes of two halves
lying near together; and in the dog, cat, martin,
&c. it resembles a belt (cingulum or zona5). Its
form in the pole-cat holds the middle between these
two structures; as there are two round masses
joined by an intervening narrower portion6.

I have discovered a most remarkable instance of
change in the form of this organ, in the hedge-hog.
For some weeks after impregnation, the placenta
includes nearly the whole circumference of the cho-
rion, and may be compared, in size and form, to a
hazel-nut. It is spongy and vascular internally;
but on the outer surface firm and tough, and ap-
proaching to cartilaginous hardness. It is not,
however, of uniform strength throughout; but
thinner and more flexible towards the concave side
of the cornua uteri, than on the opposite part. As
pregnancy advances, this thinner portion increases,
and gradually assumes a nearly membranous
structure, while the opposite thick part forms a firm
[Seite 465] and dense placenta of a saddle-like shape with ex-
tenuated margins. This lies in the more mature
foetus nearly across the ilia; so that the neighbour-
ing parts are protected from any injury, which
might have arisen from accidental pressure. For
the final purpose of this singular, and, as far as I
know, unique confirmation, is the preservation of
the tender embryo in the abdomen of an animal,
which rolls itself up with such force, that without
this provision, the pregnant uterus and its contents
would be exposed to a most dangerous pressure.

In several species of digitated mammalia the ex-
ternal surface of the placenta is provided with a
white and apparently glandular body (corpus glan-
dulosum
Everardi7, or subplacenta), smaller than
the proper placenta, by which it is inclosed8. In
proportion as the embryo becomes more mature,
this part admits of more easy separation from the
placenta.

§ 354. The placenta of the bisulca is divided
[Seite 466] into numerous cotyledons; the structure of which
is very interesting, as it elucidates the whole physi-
ology of this organ. The parts designated by this
appellation are certain fleshy excrescences (glan-
dulae uterinae
), produced from the surface of the im-
pregnated uterus, and having a corresponding
number of flocculent fasciculi of blood-vessels (ca-
runculae
), which grow from the external surface of
the chorion, implanted in them. Thus the uterine
and fetal portions of the placenta are manifestly dis-
tinct from each other, and are easily separable as
the foetus advances to maturity. The latter only
are discharged with the after-birth, while the
former, or the cotyledons, gradually disappear
from the surface of the uterus after it has parted
with its contents. The number and form of these
excrescences vary in the different genera and
species. In the sheep and cow they sometimes
amount to a hundred. In the former animal
and the goat, they are, as the name implies,
concave eminences9; while on the contrary, in the
cow, deer, &c. their surface is rounded or con-
vex10.

§ 355. The trunks of the veins which pass
[Seite 467] from the placenta or carunculae, and of the arteries
which proceed towards these parts, are united in
the umbilical chord, which is longer in the human
embryo11, than in any other animal.

In the foal, as in the child, the chord possesses a
single umbilical vein12; whilst most other quadru-
peds have two, which unite, however, into a common
trunk near the body of the foetus, or just within
it13.

§ 356. The amnion, or innermost of the two
membranes of the ovum, which belongs to the
pregnant woman, as well as to the mammalia, is dis-
tinguished in some of the latter, as for instance in
the cow, by its numerous blood-vessels; while on
the contrary, in the human subject it possesses no
discernible vascular ramification.

§ 357. Between the chorion and amnion there
is a part found in most pregnant quadrupeds, and
even in the cetacea, which does not belong to the
human ovum; viz. the allantois or urinary mem-
brane.
The latter name is derived from the con-
nection, which this part has, by means of the
[Seite 468] urachus, with the urinary bladder of the foetus;
whence the watery fluid, which it contains, has
been regarded as the urine of the animal. The
term allantois has arisen from the sausage-like form,
which the part possesses in the bisulca and the pig14;
although this shape is not found in several other
genera and species. Thus in the hare, rabbit,
guinea-pig, &c. it resembles a small flask; and it is
oval in the pole-cat. It covers the whole internal
surface of the chorion in the solidungula, and there-
fore, incloses the foal with its amnion. It contains
most frequently in these animals (although not
rarely in the cow), larger or smaller masses of an
apparently coagulated sediment in various forms
and number, which has been long known by the
singular name of the horse-venom or hippomanes15.

Some orders and genera of mammalia resemble
the human subject in having no allantois; as the
quadrumana and the hedge-hog: nay, in the latter
animal, the urinary bladder has no trace whatever
[Seite 469] of urachus; which even exists in a certain degree
in the human subject; but its fundus is perfectly
spherical in the foetus.

§ 358. There is on the contrary in this animal,
as well as in the dog, cat, and others, a peculiar
part called the tunica erythroides, situated between
the chorion and amnion like the allantois, for
which it might easily be mistaken on the first view.
It contains a watery fluid at the commencement of
pregnancy, but is easily distinguished from an al-
lantois, as it is not joined to the fundus of the
bladder by the urachus, but is connected by means
of the omphalomesenteric veins with the mesenteric
blood-vessels of the foetus16. This connection con-
stitutes a resemblance on one hand to the yolk-bag
of the incubated bird, and on the other side to that
remarkable vesicula umbilicalis, which is observable
in the early months of pregnancy17. The tunica
erythroides,
as well as that vesicula are most com-
plete in young embryos, and are, on the contrary,
so diminished in subsequent periods, that their func-
tions must be connected with the earlier stages of
existence.

[Seite 470]

§ 359. The first trace of the formation of an
embryo cannot be discovered in the different species
of this class until a considerable time after con-
ception. The original formation, as in the human
subject, is widely distant from the subsequent per-
fection of the mature foetus18: and the growth and
formation of the members, instead of proceeding
alike in the whole class, are so ordered in particular
species, that those external organs, which are most
necessary to the young animal, according to its pe-
culiar mode of life, are formed and completed the
soonest. Hence arises the great size of the posterior
hands of the foetal quadrumana, of the feet of the
squirrel, of such animals in short as are destined to
live in trees; likewise of those of the foal and kid,
which are obliged to use their legs immediately
after birth19, when compared with the correspond-
ing parts of the mature human foetus20.

[Seite 471]

§ 360. The most important points, in which
the foetus of the mammalia differs from that of the
human subject, have been already noticed. In
other respects their structure seems to correspond1;
at least, for instance, in the membrana pupillaris2,
in the thymus, thyroid, and supernatural glands.
Some trivial points of distinction are not noticed;
such as the meconium resembling hard scybala in
in the bisulca, and animals of the mouse-kind3,
&c.

CHAPTER XXVI.
ON THE BREASTS AND TEATS OF THE
MAMMALIA.

[Seite 472]

§ 361. The nourishment of the young animal
immediately after birth, is derived in this class from
the milk of the mother, which is secreted in the
breasts. This secretion, which is peculiar to the
class in question, has given rise to the name mam-
malia,
by which Linneus has distinguished them.
Yet no teats have been hitherto discovered in the
ornithorhynchus1: and they seem also to be wanting
in the males of some other species, as the hamster,
and lemur mongoz; although this sex possesses them
in general as well as the female2. They are some-
[Seite 473] times however found in smaller number in the for-
mer sex, as in the dog; or in a different situation,
as in the horse3.

§ 362. The position and number of the teats
varies considerably in the different species. Several
irregularities occur in the latter point, particularly
among the domestic animals4. Numerous excep-
tions must be made in some species, as the domestic
sow, the guinea-pig, and others, to the general rule,
which assigns to animals twice as many teats as the
number of young, which they ordinarily produce.

Their situation is the most singular in the female
marsupial animals; where their existence can
scarcely be recognized except at the time when the
young are actually contained in the abdominal
pouch, or false belly5. (See note (A) at the end
of the chapter.)

[Seite 474]

§ 363. In the singular animals, which have
been just alluded to, as well as in those which live in
the water, or under-ground, the mammary glands,
for reasons which must be very obvious, lie flat un-
der the skin, and do not project so as to form
breasts or udders: neither do the lactiferous ducts
possess such dilatations and cavities as are observed
in the bisulca, the mare and others6. In those ani-
mals which have their breasts placed on the chest
(mammae pectorales), these organs never possess that
form, which so peculiarly distinguishes the human
female in the bloom of life. (See note (B) at the
end of the chapter.)

Additional Notes to the Twenty-sixth Chapter.

[Seite 475]

(A) The mammae and teats of the opossum tribe,
kanguroo, and some other animals, are situated in
a cavity, formed by the common integuments, at
the posterior part of the abdomen. This is gene-
rally called the false belly. Its margin contains
muscular fibres, which acting like a sphincter
muscle, close the opening. It is connected to, and
supported by the pair of bones which arise from the
pubis, and are described in the chapter on the
skeleton.

§ 37. These bones possess muscles which de-
press, and others which elevate them; and the false
belly necessarily follows their motions. The same
bones are found in the ornithorhynchus, where no
false belly exists, and where the mammae have not
hitherto been discovered.

The passage of the foetus into this receptacle at a
very early period, and its connection to the nipple,
have been mentioned in the notes to the twenty-
fourth chapter.

It may be further observed, that in the kangu-
roo, the young animal remains in the false belly, or
enters it occasionally, long after it seems capable of
providing for itself.

[Seite 476]

A species of toad, (the rana pipa, or Surinam
toad) has a structure somewhat analogous to the
false belly of the marsupial mammalia. There
are several cells, amounting in number to 70 or 80,
formed by the integuments of the back of the fe-
male. The ova are placed in these, and go through
their different changes to the formation of the young
frog. The integuments, which form these cells, ap-
pear to have no peculiarity in their organisation:
nor are the cells formed until the time at which
they are to receive the ova.

(B) The mammae of animals are not surrounded
with that quantity of fat, which is observed in the
human female: hence they are not very apparent
except at the period of suckling, when they become
distended with milk.

Another remarkable difference occurs in the
structure of the nipple. This part in women has
about fifteen openings, which are the terminations
of as many lactiferous tubes. In the other mam-
malia it is hollow, and has only one or two orifices.
Its cavity communicates with two large reservoirs,
in which the lactiferous tubes terminate.

CHAPTER XXVII.
ON THE INCUBATED EGG.

[Seite 477]

§ 364. The various vital processes of nutrition
and formation, which are carried on in the foetus of
the mammalia, while in its mother’s body, and by
means of the most intimate connexion with the pa-
rent, are effected in the incubated chick, by its own
powers, quite independently of the mother, and
without any extraneous assistance, except that of the
atmospheric air, and a certain degree of warmth.

§ 365. The egg is covered, within the shell,
by a white and firm membrane (membrana albumi-
nis
), which contains no blood-vessels. The two
layers of this membrane, which in other parts ad-
here closely to each other, leave at the large end a
space, which is filled with atmospheric air1.

This membrane includes the two whites of the
egg;
each of which is surrounded by a delicate
membrane. The external of these is the most fluid
and transparent; the inner one thicker and more
opaque: they may be separated in eggs which are
boiled hard.

[Seite 478]

The internal white surrounds the yolk, which is
contained in a peculiar membrane called the yolk-
bag.
From each end of this proceeds a white
knotty body, which terminates in a flocculent extre-
mity in the albumen. These are called the chalazae
or grandines2.

A small, round, milk-white spot, called the tread
of the cock, (cicatricula or macula), is formed on
the surface of the yolk-bag. It is surrounded by
one or more whitish concentric circles, (halones or
circuli), the use of which, as well as that of the ci-
catricula itself, and of the chalazae, is not yet ascer-
tained.

§ 366. We now proceed to notice the wonder-
ful successive changes which go on during the incu-
bation of the egg; and the metamorphoses which
are observed both in the general form of the chick,
and in particular viscera. The periods of these
changes will be set down from the hen, as affording
the most familiar example3. It will be best to
[Seite 479] give, first, a cursory chronological4 view of the
whole process, and then to make a few remarks on
some of the most important parts of the subject.

§ 367. A small shining spot of an elongated
form, with rounded extremities, but narrowest in
the middle, is perceived at the end of the first day,
not in nor upon the cicatricula, but very near that
part on the yolk-bag, (nidus pulli; colliquamentum;
areola pellucida
). This may be said to appear be-
fore-hand as the abode of the chick which is to
follow.

No trace of the latter can be discerned before the
beginning of the second day: and then it has an
incurvated form, resembling a gelatinous filament
with large extremities, very closely surrounded by
the amnion, which at first can scarcely be distin-
guished from it.

[Seite 480]

About this time the halones enlarge their circles;
but they soon after disappear entirely, as well as the
cicatricula.

§ 368. The first appearance of red blood is
discerned on the surface of the yolk-bag, towards
the end of the second day. A series of points is
observed, which form grooves; and these, closing,
constitute vessels, the trunks of which become con-
nected to the chick. The vascular surface itself is
called figura venosa, or area vasculosa: and the ves-
sel, by which its margin is defined, vena terminalis.
The trunk of all the veins joins the vena portae;
while the arteries, which ramify on the yolk-bag,
arise from the mesenteric artery of the chick.

§ 369. On the commencement of the third
day, the newly-formed heart (the primary organ of
the circulating process, which now commences) is
discerned by means of its triple pulsation; and con-
stitutes a threefold punctum saliens. Some parts of
the incubated chicken are destined to undergo suc-
cessive alterations in their form; and this holds
good of the heart in particular. In its first forma-
tion it resembles a tortuous canal, and consists of
three dilatations lying close together, and arranged
in a triangle. One of these, which is properly the
right, is then the common auricle; the other is the
only ventricle, but afterwards the left; and the
third is the dilated part of the aorta, (bulbus
aortae
).

[Seite 481]

About the same time, the spine, which was ori-
ginally extended in a straight line, becomes incur-
vated; and the distinction of the vertebrae is very
plain. The eyes may be distinguished by their
black pigment, and comparatively immense size;
and they are afterwards remarkable in consequence
of a peculiar slit5 in the lower part of the iris6.

§ 370. From the fourth day, when the chicken
has attained the length of four lines, and its most
important abdominal viscera, as the stomach, intes-
tines, and liver, are visible, (the gall bladder, how-
ever, does not appear till the sixth day), a vascular
membrane (chorion, or membrana umbilicalis) begins
to form about the navel; and encreases in the fol-
lowing days with such rapidity, that it covers nearly
the whole inner surface of the shell, within the
membrana albuminis, during the latter half of incu-
bation. This seems to supply the place of the lungs,
and to carry on the respiratory process instead of
those organs. The lungs themselves begin indeed
to be formed on the fifth day; but, as in the foetus
of the mammalia, they must be quite incapable of
[Seite 482] performing their functions while the chick is con-
tained in the amnion.

§ 371. Voluntary motion is first observed on the sixth
day; when the chick is about seven lines in length.

Ossification commences on the ninth day; when
the ossific juice is first secreted, and hardened into
bony points (puncta ossificationis). (See the note
to § 5) These form the rudiments of the bony
ring of the sclerotica, which resembles at that time
a circular row of the most delicate pearls7.

At the same period, the marks of the elegant
yellow vessels (vasa vitelli lutea), on the yolk-bag,
begin to be visible.

On the fourteenth day, the feathers appear; and
the animal is now able to open its mouth for air, if
taken out of the egg.

On the nineteenth day it is able to utter sounds;
and on the twenty-first to break through its prison,
and commence a second life.

§ 372. We shall conclude with one or two re-
marks on those very singular membranes, the yolk-
bag and chorion, which are so essential to the life
and preservation of the animal.

The chorion, that most simple yet most perfect
temporary substitute for the lungs, if examined in
the latter half of incubation in an egg very cautiously
opened, presents, without any artificial injection, one
[Seite 483] of the most splendid spectacles that occurs in the
whole organic creation. It exhibits a surface co-
vered with numberless ramifications of arterial and
venous vessels. The latter are of the bright scarlet
colour; as they are carrying oxygenated blood to
the chick; the arteries on the contrary are of the
deep or livid red, and bring the carbonated blood
from the body of the animal8. Their trunks are
connected with the iliac vessels; and, on account of
the thinness of their coats, they afford the best mi-
croscopical object for demonstrating the circulation
in a warm-blooded animal.

§ 373. The other membrane, the membrana
vitelli,
is also connected to the body of the chick;
but by a two-fold union, and in a very different
manner from the former. It is joined to the small
intestine, by means of the ductus vitello-intestinalis9
(pedunculus, apophysis); and also by the blood-
vessels, which have been already mentioned (§ 368),
with the mesenteric artery and vena portae.

[Seite 484]

In the course of the incubation the yolk becomes
constantly thinner and paler by the admixture of
the inner white. At the same time innumerable
fringe-like vessels with flocculent extremities, of a
most singular and unexampled structure, form on
the inner surface of the yolk-bag, opposite to the
yellow ramified marks above-mentioned (§ 371);
and hang into the yolk. There can be no doubt
that they have the office of absorbing the yolk, and
conveying it into the veins of the yolk-bag10; where
it is assimilated to the blood, and applied to the nu-
trition of the chick. Thus in the chicken, which
has just quitted the egg, there is only a remainder
of the yolk and its bag to be discovered in the ab-
domen. These are completely removed in the
following weeks, so that the only remaining trace
is a kind of cicatrix on the surface of the intestine.

THE END.

Notes
*.
[Seite vii]

Blasius has given a collection of the writings of seve-
ral authors on the anatomy of particular animals, in one
volume 4to, entitled ‘“Anatomia Animalium Figuris variis
illustrata
’, Amstel. 1681, which may still be consulted with
[Seite viii] advantage, particularly on account of the plates. Cuvier’s
Lêçons d’Anatomie comparée, in five large octavo volumes, form
a very valuable and useful repository of facts in Comparative
Anatomy; but the subject is treated at such length, and
with so many uninteresting details, that the book is by no
means adapted for the use of students. There is a most ad-
mirable description of the anatomy of the class Birds in
the fourth volume of Dr. Rees’s New Cyclopaedia, from the
pen of Mr. Macartney: and it were much to be wished,
that we had an account of the whole animal kingdom from
the same able hand.

1.
[Seite xvii]

The ornithorhynchus is an exception to this rule; as it pos-
sesses only two ossicula; and according to our author, other
animals only possess three; as the os lenticulare is represented by
him as an apophys of the incus.

1.
[Seite 1]

Parts of a really bony structure are found only in a few
insects and worms: viz. in the stomach of the lobster, and
other species of the genus cancer; in the mouth of the sea
hedgehog (echinus), &c. These parts at least resemble true
bones more than that body, which is commonly called cuttle-
fish bone;
for the description of which see note (A) at the end
of the chapter.

2.
[Seite 1]

There are a few exceptions to the general rule, that ‘“all
the bones of an animal enter into the formation of its skeleton:
”’
viz. the bone of the tongue, commonly called os hyoides; the
bone of the penis, of several mammalia; the bony ring
in the sclerotica of birds; the clavicular bones of some mam-
malia, &c.

(To these instances we must add two others, which, though
not enumerated by the author, are sufficiently remarkable
to deserve notice: viz. the whole anterior extremity in such
mammalia, as possess no clavicles; and the abdorminal fins
of fishes, which correspond to the posterior extremities of
other animals.) T.

3.
[Seite 1]

See Galen’s remarks on this subject, when speaking of
the resemblance between the ape and the human subject; in
the 1st book of his Chef-d’oeuvre de Anatomicis Administra-
tionibus,
tom. 4. p. 26. Chartier’s edition.

4.
[Seite 2]

The red tint, which the bones of animals receive in con-
sequence of madder being mixed with the food, is observed
by Ant. Misaud, in his Centuriae Memorabilium seu Arcanorum
omnis generis,
p. 161. Cologne, 1572. 12mo.

It is remarkable, that this well known experiment meets
with very imperfect success in cold blooded animals.

*.
[Seite 2]

A section of a grinding tooth of the elephant, or of any
other herbivorous animal, as the horse, ox, &c. shews that
its substance contains parts differing considerably in appear-
ance. Besides the processes of enamel, which are intermingled
throughout with the bone, there are two kinds of osseous
structure of different colours. In the above remark, the author
probably alludes to this circumstance, although he has not
particularly described this formation in that part of his
work, which treats on the teeth. See the additional obser-
vations on that subject at the end of the Chapter. T.

5.
[Seite 2]

This has however been asserted without foundation of
some animals: thus Nicholls, in his Compend. Anat. p. 7,
fays that the amedabad finch (fringilla amandava) has yellow
bones; and others have stated the same circumstance re-
specting the golden pheasant, (phasianus pictus). I have dissect-
ed both these animals, and found the assertions to be in-
correct.

6.
[Seite 3]

Abulfazel, the vizier of Akber the Great, has re-
marked this of the fowls at Indore, and Neermul in Berar;
in his classical work Ayeen Akbery, vol. 2. p. 72. and Niebuhr
has stated it of those at Persepolis. Travels, vol. 2.

(Mr. Hunter is said to have discovered that the blackness
resides in the periosteum. Rees’s Cyclopaedia, Ast. Birds.) T.

*.
[Seite 3]

For a further account of the differences in the structure
of bones see note (A) at the end of the chapter.

7.
[Seite 3]

The erroneous opinion, which Aristotle held, of the
want of marrow in the bones of the lion, does not require an
express refutation. On that subject, as well as on some other
mistaken assertions, see R. Hener apolog. pro Vesalio ad-
versus
Sylvium. Venet. 1555. 8vo. p. 27.

8.
[Seite 4]

It is well known that the incubation of the chick occu-
pies twenty-one-days. The commencement of ossification is
not perceptible before the beginning of the ninth day; which
corresponds with the seventeenth week of human pregnancy.
In the human embryo the first points of ossification may be
discerned in the seventh or eight week after conception, (cer-
tainly not in the third or fourth week, as some great anato-
mists have lately supposed). These facts shew how little con-
fidence can be placed in that remark of Haller’s, which
concludes his excellent observations on the formation of the
bones in the incubated chick. ‘“The facts, which we have
shewn in the bones of the chick, will hold good of those of
the other classes of animals, and of man.”’

*.
[Seite 4]

In note (B) at the end of the chapter, there is a short
account of the composition of the different bony substances,
which belong to the various classes of animals. T.

9.
[Seite 4]

An example occurs in the closure of the fontanells. I
have found these openings of considerable size in young
foetuses of the ferae and pecora, but could hardly discern any
[Seite 5] trace of them at the time of birth; nothing at least which
could be compared to their magnitude in a human foetus of
nine months. When we compare the pelvis, and the whole
mechanism of parturition in the woman, with those of the
female quadruped, the cause of this difference appears. We
then discover, why the yielding and overlapping of the large
bones of the cranium, which is chiefly effected by the fon-
tanells, is only required to facilitate the birth of the human
foetus.

1.
[Seite 12]

This is the case, at least, with my specimen: the cra-
nium, destitute of sutures, considerably resembles that of a
bird in this point.

*.
[Seite 12]

See note (A) at the end of the chapter.

2.
[Seite 12]

This is meant to apply to adult birds; for young indi-
viduals have at least separate bones in their crania, if they
are not connected by real denticulated sutures.

*.
[Seite 13]

This exception is not strictly correct; as the duck-billed
animal has been found to possess a peculiar kind of horny
teeth. See the additional note to § 30. T.

3.
[Seite 14]

A profile view answers as well for this purpose as a
view from above. I have explained the use of the latter,
(which I call norma verticalis) in comparing the national
forms of human crania, in the 3d edition of my work, De
Generis humani Varietate Nativa,
p. 203. and in the 4th, De
cas. Cran. divers. Gent.
p. 12.

4.
[Seite 15]

See Merrem’s Anatomy of the Domestic Mouse; in
his Miscellaneous Observations on Natural History: and Meyer’s
Prodromus Anat. Murium; who calls it os transversum.

*.
[Seite 15]

See note (B), at the end of the chapter.

†.
[Seite 15]

See note (C), at the end of the chapter.

5.
[Seite 15]

This completely untailed baboon, was first described by
Wurmb, (who very wrongly called it the great orang-outang,
or pongo) in the 2d vol. of the Transactions of the Batav. So-
ciety.
I saw a drawing of its monstrous skeleton, which is
four feet two inches high, at the cabinet of the Hague, in
December 1791.

6.
[Seite 16]

See Daubenton, on the different Situation of the great Occi-
pital Foramen in Man and Animals,
in the Mem. de l’Acad. des
Sc. de Paris,
1764. On the difference, which we are now
considering, this excellent zootomist founded his occipital line,
which has been employed in the comparison of different
crania with each other. He draws two lines, which inter-
sect each other in the profile of the skull: One passes from
the posterior margin of the great foramen, (which, in almost
all mammalia, is also the superior one,) through the lower
edge of the orbit; the other takes the direction of the open-
ing itself, beginning at its posterior edge, and touching the
articular surface of the condyles. He determines, accord-
ing to the angle formed by the junction of these two lines,
the similarity or diversity of the form of crania.

This angle is, however, but an imperfect criterion; for
its variations are included between 80° and 90° in almost all
quadrupeds, which differ very essentially in other points.
And small variations occur in the individuals of one and the
same genus.

*.
[Seite 16]

See note (D), at the end of the chapter.

7.
[Seite 17]

In sheep affected with the staggers, where the hydatid is
large, and situated at the surface of the brain, I have found
this part of the bone almost completely absorbed; so that it
yielded to pressure, and appeared like a thin cartilaginous
membrane.

8.
[Seite 17]

That observation, which Eustachius makes, concern-
ing the sutures of apes, must therefore be understood with
some limitation; ‘“they are always so obscure, as scarcely
ever to deserve the name of sutures.”’ Ossium examen, p. 173.

9.
[Seite 17]

To determine this with greater precision, Camper in-
stituted the facial line; the application of which is most mi-
nutely explained in his posthumous work, ‘“On the natural
Differences of the Features,
&c.”’ Like Daubenton, he draws
on the profile of the cranium two straight lines, which in-
tersect each other; but in different directions from those of
the French anatomist. An horizontal line passes through the
external auditory passage, and the bottom of the cavity of
the nose; this is intersected by a more perpendicular one, pro-
ceeding from the convexity of the forehead, to the most pro-
minent point of the upper jaw, or of the intermaxillary bone.
The latter is the proper facial line; and the angle, which it
forms with the horizontal line, determines, according to
Camper, the differences of the crania of animals, as well as
the national physiognomy of the various races of mankind.

[Seite 18]

I have mentioned my objections to its application, in the
latter point of view, in my work, De Generis Humani Variet.
Nativ.
3d edit. p. 200. Concerning its use, as applied to
the crania of animals, the same observations which were
made on the line of Daubenton will hold good, mutatis
mutandis. About three-fourths of all the species of quad-
rupeds, which we are hitherto acquainted with, whose crania
differ extremely in other respects, have one and the same
facial line.

*.
[Seite 18]

For a more particular account of the relative propor-
tions of the cranium and face, together with the measure of
these, according to the rules of Camper, see note (E), at the
end of the chapter.

10.
[Seite 18]

Gotth. Fischer on the different forms of the intermaxillary
bone in different animals,
with plates, in German. Leipzig,
1800, 8 vo.

11.
[Seite 18]

Vesalius de c.h. fabricâ, p. 46, fig. 1.

12.
[Seite 19]

On this account I prefer the term intermaxillary bone,
to that of os incisivum, which is employed by Haller. –

Blair, in his excellent account of the anatomy of the ele-
phant, calls it os palati; and Vitet os maxillaire intérieur.

13.
[Seite 19]

In human crania, at least those of the foetus, and young
children, there is at the same part a small transverse slit
near the foramen incisivum, of which Fallopius gave the
following accurate account in the year 1561: ‘“I find this
division to be rather a slit than a suture, since it does not se-
parate one bone from the other, nor does it appear exteriorly,
nor join two bones; which is the office of sutures.”’ Obs. Anat.

Hence I was much surprised to find Vicq d’Azyr in 1780
discover in this point an unexpected resemblance between the
cranium of the human subject, and of quadrupeds. Mem.
de l’Acad. des Sc.
1780.

In the celebrated dispute of the 16th century, whether
Galen’s osteology was derived from the skeleton of man
or the ape, Ingrassias argued for the latter side of the
question, from Galen’s having ascribed an intermaxillary
bone to the human subject. And the same author, in his
classical ‘“Commentarii in Galeni Librum de Ossibus,”’ Panorm,
1603, fol. particularly points out the parts; ‘“where Galen,
led astray by the dissection of apes, deviates from the true
construction of the human body.”’

*.
[Seite 20]

Its great size in these animals is accounted for by the
magnitude of the incisor teeth, which it contains. T.

14.
[Seite 20]

I cannot repeat here, what I have observed in my book
De Generis Humi. Var. Nat. on the subject of the intermaxillary
bone; of which, as is there stated, not the least trace could
be discovered in the crania of some apes and baboons, although
the individuals were young. Can it be supposed, that in
these instances it was consolidated to the neighbouring bones
at a young period of life, when all the other sutures were in
a state of perfection?

Fischer could discover no trace of this bone in several
mammalia of other orders; viz. the three-toed sloth, (bradypus
tridactylus
) and the horse-shoe bat (vespertilio ferrum equinum).
See his work above quoted. Yet he admits it as possible
that the bone may have been broken off, at least in the sloth.
In short, all the exceptions, which we have just enumerated,
require a more accurate investigation in numerous and per-
fect specimens from different periods of life. (See note (F)
at the end of the chapter.)

15.
[Seite 21]

In many instances, as in the lion, the openings of these
large foramina are very visible in the palate, during life. See
J. Ridinger’s Delineation of the tame lion, which was exhibited
in Germany in
1760, fol.

16.
[Seite 21]

See Pinel Recherches sur une nouvelle methode de classification
des quadrupêdes,
in the 1st vol. of the Actes de la Societé d’His-
toire Naturelle de Paris.

*.
[Seite 22]

See note (G) at the end of the chapter.

*.
[Seite 23]

See note (H) at the end of the chapter.

17.
[Seite 23]

Geoffroy in Mémoires de la Societé d’Histoire Naturelle de
Paris,
an. 7. cahier 1.

18.
[Seite 24]

I have collected about twenty instances, from the mid-
dle of the 16th century downwards, in which horned hares
are said to have been found, with small branches like those
of the roebuck, both in different parts of Europe, and in the
East Indies. Were this fact ascertained, it would furnish
another striking point in which these animals resemble the
pecora. The fact is suspicious, because I have not yet been
sufficiently satisfied of a single instance in which the horns
were on the hare’s head, although every trouble has been
taken to procure information; and they appear in the draw-
ings, which I possess, by far too large for a hare.

19.
[Seite 24]

Anomalous instances, in which the females have pos-
sessed horns, may be seen in Stahl, de cornu cervi deciduo,
Hal. 1699. Leopold, diss. de alce, Bas. 1700. Hoy in the
Linnean Trans. vol. 2. p. 356.

I possess a coloured drawing, and accurate account of a
horned roe, which was shot in Hanover.

*.
[Seite 24]

See note (I) at the end of the chapter.

20.
[Seite 24]

The annual reproduction of these horns constitutes, in
many points of view, one of the most remarkable phaeno-
mena of animal physiology. It affords a most striking proof;
[Seite 25] 1st, of the power of the nutritive process, and of the rapid
growth, which is dependant on this in warm-blooded animals.
For the horn of a stag, which may weigh a quarter of a
hundred, is completely formed in ten weeks. 2dly, of a
limited duration of life in a part of an animal, entirely inde-
pendent on the life of the whole animal; (which in the stag
extends to about 30 years). 3dly, of change of calibre in
particular vessels. For the branches of the external carotid,
which supply the horn, are surprisingly dilated during its
growth; and recover their former area when that process
has ceased. 4thly, of a peculiar sympathy, which is mani-
fested between the growth of the horns, and the generative
functions. For castration, or any essential injury of the or-
gans of generation, impedes the growth, alters the form, or
interrupts the renewal of the horns. See Russell’s expe-
riments in his ‘“Economy of Nature in acute and chronical Dis-
eases of the Glands.
”’ It has also been asserted, but without a
sufficient proof hitherto, that injuries of the newly formed
horn render the stag impotent for some time. Berlin Soc. of
Inquirers into Nature,
vol. 4. p. 360.

21.
[Seite 25]

The frontal process in the young giraffe, constitutes an
epiphysis, which is connected to the frontal bone by a crust
of cartilage; but afterwards becomes consolidated to the
bone.

22.
[Seite 26]

See Pinel sur les os de la tête de l’Elephant in the Journal
de Physique,
tom. 43. p. 54.

23.
[Seite 27]

The singular, but very common error, of considering the
halves of the lower jaw of the whale, as ribs, has been al-
ready refuted by Rondelet, de piscibus, p. 53.

*.
[Seite 27]

See note (K) at the end of the chapter.

†.
[Seite 27]

See note (L) at the end of the chapter.

24.
[Seite 27]

See J.G. Duverney, Lettre contenant plusieurs nouvelles
Observations sur l’Osteologie,
Paris, 1689, 4to.

[Seite 28]

J.J. Kober de dentibus, eorumque diversitate, August 1774.
4to.

P.M.G. Broussonet Comparaison entre les dents de l’homme
et celles des Quadrupedes
in Mem. de l’Acad. des Sc. de Paris,
1787.

*.
[Seite 28]

See note (M) at the end of the chapter.

†.
[Seite 28]

See note (N) at the end of the chapter.

25.
[Seite 28]

Not to mention other peculiarities of ivory, which have
induced some modern naturalists to consider it as a species of
horn, the difference between its structure and that of the bone
of teeth is evinced in the remarkable pathological pheno-
menon, resulting from balls, with which the animal has been
shot when young, being found on sawing through the tooth,
[Seite 29] imbedded in its substance in a peculiar manner. Haller
employed this fact, both to refute Duhamel’s opinion, of
the formation of bones by the periosteum, like that of wood
by the bark of a tree; as well as to prove the constant reno-
vation of the hard parts of the animal machine. It is still
more important in explanation of that ‘“nutritio ultra vasa”’
which is particularly known through the Petersburg prize dis-
sertation. Instances of the fact above-mentioned may be seen
in Buffon, 4to. ed. tom. ii. p. 161. in Gallandat over de
Olyphants Tanden
in the Verhandelingen der Genootsch, te Vlissingen
p. 352. tom. 9. and in Bonn descr. thesauri Hoviani, p. 146.
In all these cases the balls were of iron. I possess a similar
specimen.

But there is a still more curious example in my collection,
of a leaden bullet contained in the tusk of an East Indian
elephant, which must have been equal in size to a man’s
thigh, without having been flattened. It lies close to the
cavity of the tooth; its entrance from without is closed as it
were by means of a cicatrix; and the ball itself is surrounded
apparently by a peculiar covering. The bony matter has
been poured out on the side of the cavity in a stalactitic form.
(See note (O) at the end of the chapter.)

26.
[Seite 29]

This black vitreous matter is sometimes covered with a
crust of a metallic shining bronze colour; particularly in the
[Seite 30] domesticated horned cattle, and sheep. See Stobaeus de
inauratione spontaneâ dentium quorundam animalium
in Act liter.
Suecic.
vol. 3. p. 83, 1733.

*.
[Seite 30]

See note (P) at the end of the chapter,

†.
[Seite 30]

See note (Q) at the end of the chapter.

26.
[Seite 31]

I must refer to the 5th part of my ‘“Delineation of Sub-
jects, relating to Natural History;
”’ for what is there said on
the question, whether the narwhal has really one or two
of these teeth. (See note (R) at the end of the chap-
ter).

27.
[Seite 32]

This is the case in the brown bear of the Alps, of which
I have three crania; with a black American; with one
whose country is unknown, belonging to the National Mu-
seum at Paris; and with the Polar bear; of all which, I
possess excellent drawings, through the kindness of professor
Cuvier. These small teeth are wanting in the fossil remains
of a prodigious bear (ursus spelaeus), towards the osteology of
which, I have a large collection, from the three most cele-
brated caverns in Germany, viz. that of Scharzfelder
in the Harz, of Gailenreuter in the Fichtelberg, and
of Altensteiner in Thuringerwald.

28.
[Seite 32]

In some apes and baboons, the front bicuspis of the lower
jaw, has a peculiar formation, being elevated into a sharp
point, like those of the ferae. See the excellent representa-
tion of the cranium of the mandril (Simia Maimon) in Che-
selden
’s Osteography.

29.
[Seite 33]

I find, that the difference between the bicuspides and
molares, is noticed in the first anatomical compendium,
which was compiled from human bodies, viz. the celebrated
Anatomia partium Corp. human. written by Mondini in the first
half of the fourteenth century. For he enumerates in each
jaw four ‘“maxillares,”’ and six ‘“molares,”’ besides the incisor
and canine teeth, p. 370, of the classical edition, which is
accompanied with Berengar’s Commentaries. I have also
found, that this distinction of the two kinds of grinders, is
noticed in that famous volume of admirable anatomical
drawings, by the incomparable Leonardo de Vinci, which
is preserved in his majesty’s library.

30.
[Seite 33]

This is the case also in the monstrous fossile animal incogni-
tum
of the Ohio (mammut Ohioticum), which has been called
the carnivorous elephant. See the 2d part of ‘“Delineations
of Subjects relating to Natural History
’, tab. 19.

31.
[Seite 33]

I say, ‘“several;”’ because in some, as the marmot, the
whole crown is covered with enamel.

32.
[Seite 33]

For the internal structure of the molar teeth of pecora,
see Hollmann de OJfibus Fossilibus, in the Commentar. Reg. Soc.
Scient. Götting.
t. 2. p. 263. And Schreger, in Isenflamm
and Rosenmuller’s ‘“Contributions towards Anatomy,”’ vol. 1.

33.
[Seite 33]

The specifically different forms of the layers of enamel,
in the African and Asiatic elephants, may be seen in the ‘“De-
lineations,
”’ &c. part 2. tab. 19.

*.
[Seite 33]

See note (S), at the end of the volume.

*.
[Seite 34]

See note (T), at the end of the chapter.

34.
[Seite 35]

See the detailed description of the change of the teeth
in the horse, by Tenon, ‘“Sur une Methode particulière d’etudier
l’Anatomie
’, in the Mem. de l’Institut. National, t. 1. p. 558. [...]

35.
[Seite 35]

In the skull of a young orang-outang of Borneo, which I
possess, through the kindness of Mr. Van Marum, there are
no bicuspides.

36.
[Seite 35]

This is excellently seen in the cranium of a young
African elephant, belonging to the museum of the Academy.

37.
[Seite 35]

See Prof. Brugman’s remarks on this subject, in Van
Maanen,
Dis. de Absorptione Solidorum. Lugd. Bat. 1794.

*.
[Seite 35]

See note (U), at the end of the chapter.

38.
[Seite 35]

I have given a drawing in the Petersburgh Prize Dis-
[Seite 36] sertation on Nutrition, 1789, 4to. of the peculiar formation of
these vertical layers in the molar teeth of the elephant, before
they appear through the gum; and particularly of the man-
ner, in which the enamel exudes from the bony substance in
small moleculae.

39.
[Seite 36]

Hence it has been observed in the glires, tint when the
upper or lower pair of incisors is lost, the opposite teeth grow
out to a monstrous length. A similar growth takes place,
when these animals are confined to soft food. See Morton’s
Natural History of Northamptonshire, p. 445.; and Achard’s
Chymico-physical Writings, p. 161. (See note (Q), at the end
of the chapter).

*.
[Seite 37]

See note (V), at the end of the chapter.

40.
[Seite 37]

The connection which this structure has with the teeth
and jaws of these rapacious animals, is pointed out by
Eustachius, De Dentibus, p. 86.

†.
[Seite 37]

Sec note (W), at the end of the chapter.

41.
[Seite 38]

Galen, in his Osteology, describes the transverse pro-
cesses as having this direction; from which circumstance, as
well as from his description of the sacrum and os coccygis, and
several other passages, Vesalius shewed that the work was
drawn up from the examination of apes, not of the human
subject. See his Epistola rationem modumque propinandi radicis
chynae decocti pertractans,
1546. p. 49.

42.
[Seite 38]

Vesalius de Corp. Hum. Fabricâ, p. 99.

43.
[Seite 38]

Camper states, that the sacrum of this animal has three
pieces: in my specimen, however, there are manifestly four.

44.
[Seite 38]

Tyson’s Anatomy of a Pigmy, edition of 1751, p. 89.

*.
[Seite 38]

See note (X), at the end of the chapter.

*.
[Seite 39]

A somewhat similar structure is found in the armadillo;
in which animal, the whole pelvis has a very anomalous for-
mation. Its skeleton, which is altogether very curious, is ac-
curately described by Wiedemann, in his ‘“Archives of Zoology
and Zootomy,
”’ 1 vol. p. 106. There is also a delineation of
the skeleton of an armadillo, prefixed to the 8th chapter of
Cheselden’s Osteography.

45.
[Seite 39]

When an opossum or monkey loses a portion of the tail,
(an accident which has often led to confusion in determin-
ing the species) a peculiar knotty excrescence, sometimes of
a carious appearance, takes place at the truncated extremity.

46.
[Seite 39]

B.G. Schreger, Pelvis Anim. Brutorum cum Humanâ
Comparatio.
Lips. 1787. 4to. Autenrieth et Fischer,
Observations Pelvi Mammalium. Tubing. 1798–9.

47.
[Seite 40]

E. Home, On the Mode of Generation of the Kangaroo.
Philos. Transact. 1795.

48.
[Seite 40]

Daubenton, vol. 10. tab. 51. (I refer here, and in other
places, where a similar quotation occurs, to the original 4to.
edition of Buffon’s work. It cannot, with propriety, be
quoted under the name of Buffon, since it is well known,
that the zootomical part was furnished by Daubenton, and
has been omitted in most of the subsequent editions.)

*.
[Seite 40]

See note (Z), at the end of the chapter.

49.
[Seite 41]

This is one of those instances, illustrating the subject of
the nisus formativus, which occur so abundantly in zootomy.
It shews, in the function of generation, an union of the teleo-
logical
and mechanical principles, which were formerly thought
to be incompatible with each other. The formation of this
anomalous pair of bones, for the purpose of supporting the
abdominal pouch of the female, is a clear instance of the
teleological principle, that is, it shews a peculiar part, formed
for a certain purpose. Their existence in the male, where
the end and purpose of their formation do not exist, shews
the mechanical principle; as if they had been merely framed,
in compliance with some general model, for the structure of
the species.

50.
[Seite 41]

Rondelet, De Piscibus, p. 461. Tyson’s Anatomy of a
Porpoise.
London, 1680, p. 28.

51.
[Seite 42]

This at least is the case in the skeleton of the Asiatic
elephant at Cassel. Blair found the same number in the
individuals of which he has given so excellent an account;
and a manuscript Italian description of the elephant, which
died at Florence in 1657, confirms this statement. Allen
Moulins
on the contrary (in his Anatomical Account of the
Elephant burned in Dublin.
London, 1682, 4to.) and Dau-
benton
represent the number of pairs as 20.

52.
[Seite 42]

It is hardly necessary to remind the readers, that the
[Seite 43] terms anterior, posterior, superior, and inferior are always ap-
plied to quadrupeds with a reference to the horizontal posi-
tion of their body. Consequently the term anterior desig-
nates those parts, which, in the erect position of the human
body, are superior; and so of the others.

53.
[Seite 43]

The passages of Aristotle, Hist. Anim. 2. 1. and de In-
cesste Anim.
c. 11. and one of Pliny ii. 102. have given rise
to the singular mistake of supposing that the elbow and knee
of quadrupeds are bent in a direction exactly opposite to
that of the human subject. The error must have arisen
from the shortness of the thigh and arm bones, which lie
close to the trunk, particularly in long-legged quadrupeds,
and do not project freely as in man, the quadrumana, the bear,
the elephant, &c. Hence the different bones of the extremi-
ty in these animals, have been compared to such parts in
the human body as do not in reality correspond with them.
See on this subject Fab. ab aquapend, de mocu locali anima-
lium secundum totum,
in his Oper. Anat. p. 343, Albinus’s ed.
and Barthez des mouvemens progressifs de l’Homme in the Jour-
na1 des Scavans,
January 1783. p. 34.

54.
[Seite 44]

J.G. Haase, Comparatio clavic. Anim. brut. cum humanis.
Lips. 1766, 4to. Vico-d’Azyr sur les clavicules and les os
clavic,
in Mem. de l’Acad. des Sciences, 1785.

55.
[Seite 44]

The use of the clavicles in some of the animals here
enumerated is well pointed out by Fab. Hildanus in his
‘“Short Description of the excellence of Anatomy.”’ Bern. 1624–8.
p. 219.

56.
[Seite 44]

Hence Serae compares it to the sesamoid bones. See
his ‘“Works relating to Natural History.”’ Naples, 1766, 4to.
p. 84.

57.
[Seite 44]

Pallas Specilegia Zoologica, Fasci. 14. p. 41.

59.
[Seite 46]

I have seen a fossil preparation in the cabinet at Nurem-
berg
, which formerly belonged to Hagen, consisting of
three slender tubes articulated to each other length-wise,
and supposed to be the petrified wing of a bird. From ob-
serving the simplicity and thinness of the middle tube, I
should not hesitate in ascribing it to a large Asiatic bat.

59.
[Seite 47]

J.B. Covolo De Metamorphosi duorum Ossium Pedis in Qua-
drupedibus aliquot,
Bonon, 1765, 4to. and Fougeroux in the
Mem. de l’Acad. des Sc. 1772, p. 520.

60.
[Seite 47]

See Stubbs’s most excellent ‘“Anatomy of the Horse.”’
tab. 1.

61.
[Seite 48]

This apparently minute circumstance, like many similar
ones, has assisted me in determining concerning the great
fossile bones which are occasionally found.

62.
[Seite 48]

Aristotle, Hist. Anim. l. 2. c. 1. For the various ap-
pellations of this well known bone in most of the European
and Oriental languages; and for its form in different ani-
mals; see Th. Hyde, Historia Talorum in the 2d vol. of his
Syntagma Dissertationum. Oxon. 1767, 4to. p. 310.

63.
[Seite 49]

This is also the case with the manati (walrus) whose
front extremities were formerly taken for Siren’s hands, thus
in Bartholin Hist. Anat. Cent. 2. p. 188.

1.
[Seite 98]

As that excellent naturalist Belon, has already shewn
in his ‘“Histoire de la Nature des Oiseaux, avec leurs Naifs Por-
traits retirez du Naturel.
”’ Paris, 1555. fol. p. 40.

2.
[Seite 98]

Consult on this subject Vinc. Malacarne ‘“of the Parts
relating to the Brain of Birds
”’ in the Memoirs of the Italian
Society,
tom. 1 and 2.

3.
[Seite 98]

A peculiarity, which seems to be confined to the cormo-
rants,
must be here mentioned. There is a small sabre-shaped
bone at the back of its vertex, which is supposed to serve as
a lever in throwing back the head, when the animal tosses
the fishes, which it has taken, into the air, and catches them
[Seite 99] in its open mouth. But the same motion is performed by
some other piscivorous birds, who are unprovided with this
particular bone. The whole skeleton of the cormorant is re-
presented by Coiter in the 4th of his excellent plates, which
are attached to his edition of the ‘“Lectiones Fallopii de par-
tibus Similaribus,
”’ &c. Norib. 1575. folio.

4.
[Seite 99]

Herissant has given it this name in the Mem. de l’Acad.
des Sc.
1748. But Coiter has pointed it out in the work
before quoted.

5.
[Seite 99]

See Merrem’s Observations relating to Zoology, p. 120.

6.
[Seite 100]

Herissant Sur les Mouvement da Bec des Oiseaux in the
Mem. de l’Acad. des Sciences, 1748. p. 345, with excellent
plates.

7.
[Seite 100]

Labillardiere says also of the upper mandible of the
pelicanus varius; ‘“cette Mandibule est mobile, comme cells dec Per-
roquets.
”’ Relation du Voyage, &c. 1. p. 210.

8.
[Seite 100]

This at least is the case, in a skull of this extraordinary
animal in my collection.

9.
[Seite 100]

A most remarkable sexual difference appears in the skull
of the crested bens: in these the frontal portion of the cranium
is dilated into an immense cavity; on which the crest of
feathers is placed. This degeneracy of the formative im-
pulse, which is propagated to the offspring, is quite un-
paralleled in the whole animal kingdom. See Stobaeus in
[Seite 101] Act. Liter Suec. v. 3. 1730. Pallas Spicileg. Zoolog. fas. 4.
Sandifort Museum Lugd. Batav. vol. 1. p. 306.

I have lately examined several heads of such hens in a
fresh, and have found that this peculiar dilatation of the
cranium is filled by the hemispheres of the cerebrum; and
it is separated from the posterior part, which holds the cere-
bellum, as in the common hen, by an intermediate con-
tracted portion.

10.
[Seite 101]

See J.T. Klein, Stemmata Avium. Lips. 1759. 4to.

*.
[Seite 102]

See note (D), at the end of the chapter.

*.
[Seite 103]

This peculiarity of structure is accounted for by ob-
serving, that these birds have not the power of flying.
The wings, which are very small, assist in balancing the body,
as they run.

11.
[Seite 103]

For an account of several differences in their structure,
See Vicq dAzyr in his ‘“Memoires pour servir a l’Anatomie
des Oiseaux,
”’ in the Mem. de l’Acad. des Sc. 1772. p. 626.

*.
[Seite 104]

The ostrich and cassowary have indeed no separate furcula;
but on either side of the front of the chest, an elongated flat
bone, consisting of a rudiment of the furcula, with the clavi-
cle and scapula consolidated into one piece.

12.
[Seite 105]

Several excellent remarks on this, as well as other parts
the osteology of this class, may be found in Professor
Schneider’s instructive work, ‘“Commentar. ad reliqua Libro-
rum Frederici 2ndi Imperatoris
’, p. 30.

*.
[Seite 105]

See note (F), at the end of the chapter.

1.
[Seite 111]

Good representations of the whole skeleton may be found
Coiter, Cheselden, and particularly in J.D. Meyer’s
‘“Pastime, with Considerations of curious Representations of all
Kinds of Animals,
”’ &c.v. 1. p. 29. v. 2. p. 62. The indi-
vidual parts are represented in Giov. Caldesi’s Anatomical
Observations relating to Turtles.
Florence, 1687. 4to.

2.
[Seite 113]

Skeletons of the frogs and toads of this country (Ger-
many), may be seen in the well-known chef d’oeuvre of
Roesel, ‘“De Ranis Nostratibus.”’ The singular skeleton of
the rana pipa (Surinam toad), is accurately described and
delineated in the first fascic. of Professor Schneider’s Histor.
Amphibior.
It is particularly distinguished by the large la-
teral processes of the sacrum, and by a bony cavity (cista
Schneid.
) of unknown use, placed behind the sternum, and
belonging exclusively, as it should seem, to this animal.

3.
[Seite 113]

It must be understood, that we speak here of real teeth;
and not of what are called the denticulated margin of the
jaws.

4.
[Seite 113]

See Troja’s ‘“Memoir, concerning the singular Structure of
the Tibia and Ulna in Frogs and Toads;
”’ in his ‘“Experiments on
the Regeneration of Bones,
”’ in Italian. Naples, 1779. p. 250.

5.
[Seite 114]

The skeleton of the crocodile, is represented in N. Grew’s
‘“Museum Regalis Societatis.”’ Lond. 1681. Also in Faujas
St. Fond
, Histoire Naturelle de la Montagne de St. Pierre de
Mastricht.

6.
[Seite 114]

The skeleton of the common green lizard, may be seen in
Coiter, pl. 4; Meyer, tome 1. pl. 56; that of the sala-
mander
and waternewt are also given in Meyer; that of the
chamaeleon is prefixed to Cheselden’s 6th ch.

7.
[Seite 114]

The commencement of this kind of articulation, is seen
in the jaw of the testudines.

8.
[Seite 114]

The condyle resembles, in some measure, the pulley at
the inferior extremity of the humerus (the trochlea, or rotula
of Albinus); this, at least, is the case in the skull of an alli-
gator,
which I have before me.

The old error, of supposing that the upper jaw of the cro-
codile is moveable, and the lower, on the contrary, incapa-
[Seite 115] ble of motion, which has been adopted even by such anato-
mists as Vesalius and Columbus, has perhaps arisen from
this peculiar mode of articulation. An examination of the
cranium shews, that if the lower jaw remains unmoved, the
whole remainder of the skull may be carried backwards and
forwards by means of this joint. And such a motion is pro-
portionally easier in the present instance, than in any other
animal, both on account of the very great relative size of the
lower jaw, as well as from its anomalous mode of articula-
tion. There is, however, no motion of the upper jaw-bone
only, similar to that which occurs in most birds, serpents,
and fishes.

9.
[Seite 115]

Sometimes three, according to Retzius, Animad vers.
circa Crocod.
1797. 4to.

10.
[Seite 115]

In the skeletons of three East Indian crocodiles, which I
have examined, there were ten pairs of true, and two of false
ribs. The former had bony appendages; and a third, in-
termediate portion between the chief piece of the rib and
the appendix. The abdominal sternum consisted of seven
pairs of a cartilaginous arches connected together. The six
front pairs were interrupted by open intervals; and the space
between the last pair and the pubis, was filled by a broad piece
of cartilage. A somewhat similar structure in the crocodile
[Seite 116] of the Nile, is described by S. Veslingius, in his Observ.
Anat.
p. 43; and in the alligator, by Plumier, in the Memoires
de Trevoux,
of January 1704.

11.
[Seite 116]

Skeletons of several snakes are contained in the work of
Meyer, above quoted.

12.
[Seite 116]

Specimens are delineated, for the sake of comparison, in
the 4th part of my ‘“Delineations,”’ &c. tab. 37, where the
heads of a rattlesnake (crotalus) and a boa, are represented
with their mouths open.

13.
[Seite 117]

For the probable use of this organ, which belongs so
exclusively to the rattlesnake; and for the assistance, which it
may afford to this inactive animal, by drawing towards it
the frightened birds (which, indeed, may have given rise to
the stories concerning its supposed power of fascination).
See Voigt’s Magazine, for the newest Occurrences in Natural
History,
vol. 1. p. 37. ‘“On the fascinating power of the
rattlesnake, particularly with respect to a work of Dr. Bar-
ton’s,”’ in German.

14.
[Seite 117]

This is also the case with other species of the coluber;
namely, the Egyptian coluber haje, which can dilate its neck
very considerably, when enraged.

*.
[Seite 118]

For some others remarks, concerning the head of the
amphibia, see note (C) at the end of the chapter.

1.
[Seite 121]

Delineations of the skeleton of most marine fishes are
still wanting. A beautiful view of the skate is given by
Cheselden in the beginning of his work. Meyer has re-
presented the skeletons of twenty-five fresh-water fishes in the
two first volumes of his book, which has been frequently
quoted. That of the carp may be seen in Duhamel Traité
des Pêches,
(a part of the great work entitled, Description des
Arts and Metiers,
) pl. 2. sect. 1. tab. 3.

*.
[Seite 121]

There are some excellent remarks on the skeleton of
[Seite 122] fishes in general, by Profr. Autenrieth in Wiedemann’s
Archives, vol. 1. p. 2.

On the skeletons of particular orders of fishes, see Vicq
D’Azyr
, in the 7th vol of the ‘“Memoires presentés a l’Acad.
des Sciences.
”’ It is translated into German, with remarks
and additions by Professor Schneider, in his ‘“Collection of
Anatomical Observations and Remarks towards elucidating the
History of Fishes.
”’ Leipzig, 1795. 8vo.

3.
[Seite 122]

Augustin Scilla de Corporibus Marinis lapidescentibus.
Rome, 1759. 4to. tab. 2.

4.
[Seite 123]

See Herissant in the Mem. de l’Acad. des Sc. de Paris,
1749, p. 155. And W. Andre in the Philos. Trans. vol. 74.
p. 274.

5.
[Seite 123]

One of the most surprising formations about the mouth
[Seite 124] occurs in a West Indian species of skate (raia flagellum): it
is described and delineated in the Philos. Trans. vol. 19.
p. 674. by Sloane, as the tongue of the animal. The spe-
cimen, which I possess, consists of a flat bone, about five
inches long, two broad, and of the thickness of the thumb.
It is composed of 15 curved portions, connected together
lengthwise; and each of these arches is covered above
with 60 small teeth, which lie close together.

6.
[Seite 124]

I possess a specimen of the singular bone, relating to this
[Seite 125] subject, which has been represented in the Museum Wormia-
num,
p. 270, in the Museum Regium of Jacobaeus, and in
Olearius, Gottorf. Kunsikammer; and which, for a long
time has been considered as a very obscure subject. It is
thick, of a roundish flat form, and nearly resembling a
smooth chesnut in form and size. It forms on one side a
bony point; and on the other is articulated, by means of a
very remarkable ginglymus, with two small bones of diffe-
rent magnitude, and resembling the point of an arrow. It
belongs most probably to an East Indian chaetodon, (probably
to the Ch. arthriticus Schneid); the larger piece being the
basis of the back-fin, and the smaller constituting the first
radii of that fin. See W. B ell’s Description of a Chaetodon,
called by the Malays, Ecan Bonna,
in the Philos. Trans. 1793.

1.
[Seite 129]

Partial exceptions to this general rule may be drawn;
1st, From those animals in which no mouth has been hitherto
discovered; for instance, as some animalcula infusoria, and in
a certain sense some medusae, which, instead of possessing a
simple opening, take in their nourishment through many
apertures. 2dly, From those, in which no manifest volun-
tary motion has been hitherto observed, as in several real
hydatids. Physiologists have lately gone further, and have
declared certain organized bodies, in which neither of the
above-mentioned characters, neither a mouth nor voluntary
motion could be discovered, to be animals. Such, for ex-
ample, are the dropsical bladders, occasionally found in the
abdomen of persons, who have laboured under ascites,
(rarely in any animal except man,) in vast numbers, and of
various sizes from that of a goose’s egg, to the head of the
smallest needle. I have examined a great number of these,
which were found in a dropsical old man, whose disease and
dissolution are related by Richter, in Loder’s Surgical
Journal,
vol. 3. p. 415. These differ in their whole structure,
and particularly in the formation of their membranes,
much more from the true hydatids, than from some simple
morbid watery cysts, which are met with not unfrequently in
warm-blooded animals, and consist so indisputably of a mere
unnatural formation of vessels and membranes, that no per-
son could think of ascribing to them an independent animal
existence. I have now before me similar cysts from a hen,
the largest of which, (about the size of a small hen’s egg),
like those of the above-mentioned patient, were quite un-
attached; the rest appeared, on the first examination, from
their connection with the ovarium, to be nothing else but
calyess, containing from a morbid cause, lymph instead of
yolk.

[Seite 130]

I have however lately dissected a simia cynomolgus, whose
lungs, liver, and omentum were beset with an abundance
of watery cysts of various sizes. The fluid of these cysts con-
tained an innumerable quantity of microscopical bodies,
which were found, by the employment of strong magnifying
powers, to be hydatids, with a well-formed circle of hooks,
and mouth, and consequently must be considered as true
independent animals.

2.
[Seite 130]

An accurate description and delineation of these bags
may be found in Sulzer’s ‘“Essay towards the Natural History
of the Hamster,
”’ in German, p. 41. 58. tab. 3. One of the
most masterly zoological and zootomical monographs that
has ever been published.

3.
[Seite 131]

See Home’s Life of J. Hunter, prefixed to the posthu-
ous works of the latter, on ‘“the blood, inflammation,”’ &c. p. 41.
According to Cuvier, the common camel only, with one
protuberance (the dromedary), possesses this oesophageal pouch,
and thrusts it forwards only at the rutting season. Ménagerie
du Museum National, pl. 1.

4.
[Seite 131]

Grew may be consulted respecting the oesophagus, as
well as the whole alimentary canal of several animals of the
different classes. See his Museum Regalis Societatis.

5.
[Seite 132]

See Professor Nebel, De Nosologiâ cum Hominum
Morbis comparatâ.
Giess. 1798.

6.
[Seite 132]

It seems extraordinary on the first consideration, that
the ruminating animals, in whom the passage of the food
form the first stomach into the oesophagus is very easy, should
not be excited to vomit without such difficulty.

I possess, through the kindness of Mr. Hanemann, director
of the veterinary school at Hanover, an hair-ball which was
discharged by vomiting from the stomach of a cow, which la-
boured under an affection of the digestive powers. The sub-
stance in question was discharged with violence, after the em-
ployment of some white hellebore placed under the integu-
ments of the breast. A more detailed account will be found
in Voigt’s ‘“Magazine for the newest Occurrences in Natural
History.
”’ vol. 2. p. 637.

7.
[Seite 132]

H.C. Schroeder, Digestione Animalium Carnivororum,
Goett. 1755, 4to.

8.
[Seite 133]

We must not however trust implicitly to Roederer,
when he says that ‘“the bear has two stomachs, the first and
largest of which is formed like that of a carnivorous animal,
the second and smaller like that of birds, which feed on hard
seeds.”’

9.
[Seite 133]

On the whole internal surface of the horse’s stomach,
there are found, in vast abundance, particularly in spring,
the larvae of two species of aestrus; viz. the aestrus equi (which
Linnaeus called aestrus bovis), and the ae. haemorrhoidalis, the
true history of which has been elucidated for the first time
in modern days, by that excellent veterinary surgeon, Mr.
Bracy Clark, in the Transactions of the Linnaean Society, vol. 3.
Figures of the aes. equi and its larvae are given in my ‘“Deline-
ations,
&c.”’ pl. 5.

10.
[Seite 133]

Bertin in the Mem. de l’Acad. des Sc. de Paris, 1746.

11.
[Seite 134]

This is excellently described by Sulzer, in his work
above quoted.

12.
[Seite 134]

Voyage a la Recherche de la Perouse. T. 1. p. 134.

13.
[Seite 134]

Tyson in the Philos. Trans vol. 13.

14.
[Seite 134]

Daubenton, vol. 13. p. 54. and 63. and Wiede-
mann
’s Archives, vol. 1.

15.
[Seite 134]

Tyson’s Anatomy of a Porpoise, London, 1680. 4to.
Hunter in Schneider’s ‘“Contributions towards the Natural
History of Whales.
”’ in German, pt. 1.

16.
[Seite 134]

From the multitude of writers, who have treated on
the stomach of ruminating animals, and its functions. I refer
to the following only, on account of the plates which they
have given, particularly such as exhibit the vast increase of
[Seite 135] size in the first stomach compared with the fourth, in the
early periods of life.

Observ. Anat. Collegii privati Amstelodamensis, pl. 1. p. 12.

Perrault, Essais de Physique, vol. 3. p. 211.

J.C. Peyer, Merycologia, Basil. 1685, 4to.

J.J. Harderi Apiarium, ib. 1687, 4to. p. 16.

Daubenton, tom. 4. tab. 15–18.

To which may be added, Mr. Home’s observations on
the camel’s stomach; which contain two excellent views of
the cow’s stomach by Mr. Clift, besides those of the camel.
Philos. Trans. 1806, pl. 15, 16.

17.
[Seite 135]

It is generally in this first stomach, seldom in the second,
that morbid concretions are formed, of a globular, or elon-
gated but yet rounded figure. They are composed of three
kinds of substance: viz. of hairs, of the undigested fibrous
parts of plants, or of stony matters.

The hair-balls, particularly in the cow, are formed of the
animal’s own hair, which is licked off, and gradually ac-
cumulated in the stomach. These either retain a hairy ap-
pearance externally, or they are covered with a dark polished
substance, similar to that which accumulates round their
molar teeth. (See § 23).

The balls of the chamois (aegagropilae), consisting of vegeta-
ble matters, particularly of the macerated fibres of the
aethusa meum, are found in the animals from which they de-
[Seite 136] rive their name, and are generally of a fine spongy texture,
covered externally with a smooth black coat.

Of the stony concretions, which constitute the bezoars, the
oriental ones are derived from the wild goats. Others come
from the South American species of camel. The latter are
of a yellow-grey colour; the former of a greenish-black,
with concentrical strata, and generally containing for a
nucleus a small bit of rice-straw.

In a large oriental bezoar, which I sawed through, the
nucleus consists of a red-brown, fine but compact, spongy sub-
stance, like that of the vegetable balls.

18.
[Seite 138]

This supposes a power of voluntary motion in the part.
And indeed the influence of the will in the whole affair of
rumination, is incontestable. It is not confined to any particu-
lar time, since the animal can delay it according to circum-
stances, when the paunch is quite full. It has been expressly
stated of some men, who have had the power of ruminating,
(instances of which are not very rare,) that it was quite
voluntary with them. I have known two men, who rumi-
nated their vegetable food: both assured me that they had a
real enjoyment in doing this, which has also been observed of
others: and one of them had the power of doing it, or leav-
ing it alone, according to circumstances.

19.
[Seite 138]

These facts were understood by Severino, who says
in his instructive Zootomia Democritea ‘“A penula et ollula
media revomitur ad os, hinc ruminatum ad conclave de-
scendit, et hinc postremo ad ventriculum proprie dictum.”’

20.
[Seite 138]

I have already, on another occasion, observed that the
final purpose of rumination, as applicable to all the animals,
in which it takes place; and the chief utility of this wonder-
fully complicated function in the animal economy, are still
completely unknown; what has been already suggested on
these points, is quite unsatisfactory.

Fabricius ab Aquapendente has sufficiently refuted the
old dream of Aristotle and Galen; that rumination sup-
[Seite 139] plies the place of incisor teeth, the materials of which, are
applied, in these animals, to the formation of horns. Per-
rault
and others supposed, that it contributed to the secu-
rity of these animals, which generally eat much, and are
timid, by shewing the necessity of their remaining long em-
ployed in chewing, in an open pasture. But the Indian buf-
falo
ruminates, although it does not fly even from a lion,
but rather attacks, and often vanquishes that animal. And
the wild goat dwells in Alpine countries, which are inacces-
sible to beasts of prey.

1.
[Seite 140]

That is to say, they are not swallowed, as Burt sup-
posed, in the 2d vol. of Asiatic Researches, to afford nourish-
ment; but in order to kill and bruise the insects, &c. which
form the ordinary food of the animal, and which might
otherwise, by means of their vitality, resist the chemical ac-
tion of the gastric juice; as the intestinal worms and water-
newts,
which have been swallowed, do in man and other
mammalia.

2.
[Seite 140]

The late Dr. Bloch supposed, that he had found this
part in the female bird. This was probably a mistake; for
I have lately examined a female bustard, in which there was
no trace of the part.

3.
[Seite 140]

Edwards’s Natural History of Birds, tom. 2. tab. 73. and
Schneider, Comment. ad reliqua Librorum, Frider. 2ndi, p. 9.

4.
[Seite 141]

A sea-gull, which I kept alive for some years, could swal-
low bones of three or four inches in length, so that the lower
end only reached the stomach, and was digested, whilst the
rest projected into the oesophagus, and descended gradually,
in proportion as the former was dissolved.

5.
[Seite 141]

Hunter on the Animal Economy, p. 193.

6.
[Seite 141]

This takes place in an inverse ratio to the age of the
young pigeon, as long as the old birds keep their food in
the crop. See Viridet du bon Chyle, pour la Production du Sang,
t. 1. p. 78.

7.
[Seite 141]

See Wolf, in Voigt’s Magazine, vol. 1. p. 72.

*.
[Seite 142]

It appears, however, that the bulbus glandulosus is
wanting in some birds, as the king’s fisher.

8.
[Seite 142]

Hence Valisnieri calls it in this animal, ‘“the first sto-
mach;
”’ see bis ‘“Anatomy of the Ostrich,”’ in Italian, 1713,
p. 159.

9.
[Seite 142]

For an account of several other variations in the struc-
ture of this part, in different birds, see the Parisian ‘“Mé-
moires pour servir a l’Histoire Naturelle des Animaux.
”’

10.
[Seite 142]

See note 1. § 40.

11.
[Seite 143]

Herissant thought this circumstance peculiar to the
cuckoo; and hence explained, why that bird does not incu-
bate. Mem. de l’Acad. des Sc. 1755.

12.
[Seite 143]

Haller has collected a Number of these in his Element.
Physiolog.
t. 7. p. 115.

13.
[Seite 143]

Duverney Oeuvres Anatomiques, tom. 2. p. 447.

14.
[Seite 143]

Wepfer, Cicutae Aquaticae Historia et Noxae, p. 174. This
is, on the whole, a most instructive work in this branch of
zootomy.

15.
[Seite 144]

J.C. Peyer, Anatome Ventriculi Gallinacei, in his Exercit.
de Glandulis Intestinor.
Scashus. 1677, 8.

16.
[Seite 144]

W.G. Muys, De Carnis Musculosae Structurâ. Leid.
1741. 4to. tab. 1.

17.
[Seite 144]

Monro’s Essay on Comparative Anatomy.

18.
[Seite 145]

The numerous experiments, which Reaumeur per-
formed, in order to determine the extent of this triturative
power, are universally known. There are two curious ob-
servations on this subject, less generally known. Felix
Plater found an onyx, which had been swallowed by a hen,
to be diminished by one-fourth in four days; and a Louis d’or
lost in this way 16 grains of its weight. See Swammerdam,
Biblia Naturae, p. 168.

19.
[Seite 145]

The end and use of swallowing these stones, have been
very differently explained. Caesalpinus considered it ra-
ther as a medicine than as a common assistance to digestion.
Boerhaave, as an absorbent, for the acid of the stomach.
Redi, as a substitute for teeth. According to Whytt, it is
a mechanical irritation, adapted to the callous and insensible
nature of the coats of the stomach. Spallanzani rejected
all supposition of design or object, and thought that the stones
were swallowed from mere stupidity. I think there is not
much sagacity to be discovered in this opinion, when we
consider that these stones are so essential to the due digestion
of the corn, that birds grow lean without them, although
they may be most copiously supplied with food. This para-
doxical opinion has, however, been already refuted by
J. Hunter, in his ‘“Animal Economy,”’ p. 155.; and G.
Fordyce, on Digestion, p. 23.

[Seite 146]

The use of swallowing these stones, seems to me, to consist
in this, that they kill the grain, and deprive it of its vitality,
which otherwise resists the action of the digestive powers.
(See § 92, note 1.) Thus it has been found, that if the
oats and barley given to horses, are previously killed by
heating, the animal only requires half the quantity, and yet
thrives equally.

1.
[Seite 146]

Ruysch, Thesaurus Anatomicus, 8vo. tab. 2.

2.
[Seite 147]

See Fabricius ab Aquapendente, p. 101. of the edi-
tion quoted above.

3.
[Seite 147]

Representations of the stomach of several fishes, may be
seen in the 2d vol. of Collins’s System of Anatomy. Lond.
1685, and in the ‘“Memoires presentes,”’ &c. by Vicq d’Azir.

4.
[Seite 147]

Rondelet, p. 70.

5.
[Seite 147]

In the ‘“Manual of Natural History,”’ in German, p. 298.
edition 6th.

2.
[Seite 148]

Compare, for instance, the stomach of the larva of the
papilio urticae, with that of the perfect butterfly, in Swammer-
dam
, Biblia Naturae, tab. 34. fig. 4. and tab. 36. fig. 1.

3.
[Seite 148]

There are several delineations of the stomach, in the dif-
ferent orders of this class, viz. that of the scarabaeus nasicornis,
in Swammerdam, tab. 27. Of the earth-beetle, in Rösel,
vol. 2. tab. 8. Of the stag-beetle (lucanus cervus), ibid.
tab. 9. Of the earwig, in C.F. Posselt, Tentamina circa
Anatomiam forficulae Auriculariae.
Jen. 1800, 4to. fig. 26. Of
the gryllus verrucivorus, in Rösel, vol. 2. tab. 9. Of the
silkworm, in Malpighi, de Bombyce, 1669, 4to.; in Rösel,
vol. 3. tab. 9.; and Bibiena, in the Comment. Instit. Bonom.
tom. 5. part 1. tab. 2 and 3. Of the cossus, in Lyonet’s
chef d’oeuvre, ‘“Anatomie de la Chenille”’ &c. Of the ephe-
mera horaria,
in Swammerdam, tab. 15. Of the larva of the
musca chamaeleon, ibid. tab. 41. Of the musca putris, ibid.
tab. 43. Of the louse, ibid. tab. 2.

4.
[Seite 149]

Posselt, in the work above quoted, p. 27. fig. 27.

5.
[Seite 149]

Cuvier, in the Mémoires de la Societé d’Hist. Nat. de Pa-
ris,
an. 7. tab. 4.

6.
[Seite 149]

Swammerdam, Algem. Verhandel. van de Bloedeloose Dier-
kens.
Utrecht, 1769, 4to.; arid G.H. Velschii, Hecatos-
teae Obs.
Aug. Vind. 1675, 4to. p. 71.

7.
[Seite 149]

See Willis, De Anima Brutorum, for a representation of
this in the craw-fish. Also Rösel, vol. 3. tab. 58.

1.
[Seite 149]

The following zootomists have given us representations
[Seite 150] of the stomach, in the different orders of vermes: viz. Ty
son,
of the round worm (lumbricus teres, ascaris lumbricoides),
in the Philos. Trans. vol. 13. No. 137; which may be com-
pared with Werner, Vermium Intestin. Expositio. Lips. 1782.
tab 7. Willis, of the eatrth-worm, tab. 4. Also Vandelli
Diss. de Aponi Thermis, &c. Patav. 1758, 8vo. Morand,
of the leech, in the Mem. de l’Acad. des Sc. an. 1739. As well
as Bibiena, in the Comm. Instit. Bonon. tom. 7, p. 102. Of
the slug, Swammerdam, tab. 9. Of the cuttle fish, ibid. tab.
51. As also Monro, On the Physiology of Fishes, tab. 31. Poli,
of several testacea, in his ‘“Testacea utriusque Siciliae,”’ viz. the
pholas dactilus, tom. 1, tab. 7.; the tellina planata, tom. 1.
p. 14. Mactra Neapolitana, tom. 2. tab. 19.; the venus chione,
tab. 20. Of the snail, Swammerdam, tab. 5. Of the sea
hedge-hog (echinus esculentus
), Monro, tab. 32.

2.
[Seite 150]

See Pallas, Miscellanea Zoologica, tab. 7.

3.
[Seite 150]

For instance, in the chiton cinereus, see Poli, tom. 1. tab.
3. Compare also the oesophagus of the cuttle-fish which is
furnished with teeth in the same manner. See Turber-
ville Needham
’s ‘“Nouvelles Observations Microscopiques,”’
tab. 3.

4.
[Seite 151]

Draparnaud, in the new Journal de Physique, tom. 7.
p. 146. This stomach, was lately taken by some naturalists,
for a peculiar genus, of an entirely new order of three-shelled
testacea.

*.
[Seite 169]

There is an account of the structure of this villous
coat, in several species of all the four classes of red-blooded
animals, in R.A. Hedwig’s Disquisitio Ampullularum Lie-
berkühnii,
Lips. 1797, 4to. and in K.A. Rudolphi’s Anato-
mico Physiological Transactions,
in German, p. 41.

1.
[Seite 169]

Roederer gives an accurate description of this valve in
our domestic animals, ‘“De Valvulâ coli.”’ Argent, 1768, 4to.
p. 46.

2.
[Seite 170]

As we have spoken above of the bezoars and other con-
cretions formed in the stomach, we must here take notice of
the intestinal stones, which occasionally occur in horses, and
of the valuable fecal concretions of the pikeheaded whale or
cachalot. (Physeter Macrocephalus).

The former are commonly of a yellowish grey colour; of
a globular form, shining externally, but of a dead and earthy
appearance in their fracture; not very hard; and in their
average size about equal to a billiard ball; although
they have been found as large as a man’s head: all these
external characters vary indeed considerably. The most
[Seite 171] remarkable circumstance relating to them, is their composi-
tion; according to Fourcroy and Bartholdi they consist
in the proportion of one half, of phosphate of magnesia.
They are often found in millers’ horses, which have been
fed for a long time with bran and mill-dust; there is usually
only one, but sometimes more; they are most frequent in
the colon, and have very seldom been found in the stomach
(at least of the same sort, which has been now described).
They are not discovered in general until the death of the
animal. But I find an instance, in the ‘“Epistoloe de Re Numis-
maticâ ad
Z. Goezium’, of a horse, which voided a stone of
the above-mentioned kind, as large as a hen’s egg, every
month with his faeces.

A species of globular concretions, very different from these
intestinal stones, is occasionally found in the colon, and
caecum of the horse. It is composed of fine vegetable fibres,
and resembles, on the first view, the balls of the chamois, (see
note 17, § 89). Hence Lafosse, who has described and
delineated them, calls them aegagropilae, by way of distinction
from the true intestinal stones, which he terms bezoar equinum,
see his ‘“Cours dHippiatrique.”’ 158. tab. 51. Like the
balls of the chamois, they are much lighter than intestinal
tones; and two of them are not unfrequently found together,
one being inclosed within the other.

The fecal indurations of the cachalot form the valuable
substance, known by the name of ambergris, which was for-
merly considered as an animal excrement, but has been sup-
posed latterly by some to be a fossile substance, by others to
be a vegetable resin: its animal origin is now placed beyond
all doubt. Sir Jos. Banks informed me, some time ago,
that, according to what he could learn from the English
[Seite 172] South Sea whalers, the faeces of the cachalot, which are
nearly fluid in a healthy slate, are hardened into this amber-
gris, by a kind of constipation; hence, it is only found in
weak and exhausted animals; and the firmest and most va-
luable, comes from such as seem to have died of the com-
plaint, which it has occasioned.

3.
[Seite 172]

See Valisnieri, Anatomy of the Ostrich, tab. 2.

4.
[Seite 173]

De Graaf, De Mulierum Organis Generat. Inservientibus,
tab. 17.; and G.G. Tannenberg , Spicileg. Observ. circa
Partes Genital. Masculas Avium,
Gött. 1789, 4to. tab. 2 and 3.

5.
[Seite 173]

I found these folds, so large and numerous in the rectum,
that a transvere section of the gut, presented the appearance
of a broad radiated ring.

6.
[Seite 173]

That portion of the small intestine, which corresponds
to the jejunum, was beset, in the animal which I dissected,
with innumerable small processes, like the appendiculae epiploicae,
which are occasionally found in some mammalia.

7.
[Seite 174]

See Charas, Nouvelles Experiences sur la Vipére. Par.
1672, 8vo.; and Tyson’s Anatomy of a Rattlesnake. Philos.
Trans. vol. 13, No. 144.

8.
[Seite 174]

Lorenzini, ‘“Observations relating to the Torpedo,”’ in
Italian. Flor. 1678, 4to. tab. 2.

9.
[Seite 174]

It is delineated, from another species of ray, by Swam-
merdam
, in the 4th edition of Bartholin’s Anatomy. Lugd.
Bat. 1673, p. 297; which contains much valuable informa-
tion in zootomy. Perrault has represented it in a shark,
Essais de Physique,
v. 3.

*.
[Seite 174]

For an account of the structure of the coats of the ali-
mentary canal, see note (D) at the end of the chapter.

10.
[Seite 175]

The leading work, on this subject, is very rare, ‘“Pars
altera Observ. Anat. Collegii privati, Amstelod.
”’ which was pro-
duced almost entirely by Swammerdam.

11.
[Seite 175]

In some, as the Burbot, they appear almost like a fin-
ger. Hence the part has been called the burbot’s hand or
foot. See Chr. Encelius, De Re Metallicâ. Francof. 1551,
p. 241; which contains, I believe, the first delineation of the
part.

12.
[Seite 175]

The consequences, which may be drawn from this cir-
cumstance towards the elucidation of the business of secre-
tion, have been already pointed out in my Instit. Physiol.
p. 367.

13.
[Seite 176]

Some zootomists have considered these as small intes-
tines; others as biliary ducts; and others as lacteal vessels.

14.
[Seite 176]

On this subject, as well as on several of the following
chapters, the references contained in the notes to the 106th
and 107th paragraphs, may be consulted.

15.
[Seite 176]

For a further account of the alimentary canal, in the
lower orders, see note (E) at the end of the chapter.

1.
[Seite 190]

It deserves to be remarked here, as a peculiarity of the
liver of some four-footed mammalia, which live in or about
the sea; namely, the polar bear, and some seals; that it seems
to possess some poisonous or noxious qualities when employed
for food. Heemskerk’s Companions experienced this in
the former instance at Nova Zemlia; and Lord Anson’s
squadron in the latter, on the coast of Patagonia.

2.
[Seite 191]

Some have considered the large hepatic duct of the horse
as a gall-bladder. See Sir Thomas Brown’s Pseudodoxia
Epidemica,
p. 119. ed. of 1672. This might with more
truth be said of the elephant, where the hepatic duct has a
considerable expansion just at its entrance into the intestine.

Oeuvres de Pierre Camper, tom. 2. ch. 4. § 3.

3.
[Seite 191]

Stukely on the Spleen, tab. 3. and 4.

The hepatico-cystic ducts, and the cellular structure of the
spleen, are the more worthy of mention, as they have given
rise to errors in physiology.

4.
[Seite 191]

I quote only a single instance of the peculiar appearances
of the omentum in particular species; viz. that of the racoon,
[Seite 192] (ursus lotor), which has a very remarkable structure; and
which I received from that zealous zootomist Dr. Albers,
of Bremen. It is comparatively large, and consists of in-
numerable stripes of fat, disposed in a reticular form, and
connected by an extremely delicate membrane, resembling a
spider’s web.

5.
[Seite 192]

B. Robinson, on the Food and Discharges of Human Bodies,
London, 1748–8. p. 97.

6.