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A
MANUAL
OF
COMPARATIVE ANATOMY.

[titlePage_recto] [titlePage_verso]
[titlePage_recto]
A
MANUAL
OF
COMPARATIVE ANATOMY,
TRANSLATED FROM THE GERMAN
OF
J.F. BLUMENBACH,
WITH ADDITIONAL NOTES,
By WILLIAM LAWRENCE, Esq. F.R.S.
SURGEON TO ST. BARTHOLOMEW’S HOSPITAL, TO BRIDEWELL,
AND BETHLEM HOSPITALS,
ETC. ETC.

SECOND EDITION, REVISED AND AUGMENTED,
By WILLIAM COULSON,
DEMONSTRATOR OF ANATOMY AT THE MEDICAL SCHOOL, ALDERSGATE STREET,
AND MEMBER OF THE ZOOLOGICAL SOCIETY.


LONDON:
PRINTED FOR W. SIMPKIN AND R. MARSHALL,
STATIONERS’-HALL COURT, LUDGATE STREET.

1827.
[titlePage_verso]
J. M’Creery, Tooks Court,
Chancery-lane, London.

ADVERTISEMENT.

[Seite i]

In submitting this work to the public, the Editor
deems it right to state briefly in what respects the
present edition of Mr. Lawrence’s translation of
Blumenbach differs from the original edition of
1807. The difference consists partly in the addition
of new matter, and partly in a new, and, he trusts,
improved arrangement both of the text of the author,
and of the additional notes of the Translator.

With respect to the new disposition of the matter,
the notes of Blumenbach have been incorporated,
wherever it has been practicable to effect such an union,
with the text; an arrangement which is sanctioned, in
many instances, by the authority of the author him-
self in the later editions of his work; and which will
be found, it is hoped, to contribute not less to the pro-
fit, than to the convenience of the student. Frequent
annotations necessarily divert the attention of the rea-
der from the chain of reasoning, or the detail of facts
which the text may present to him; and there is the
less reason for isolating the information contained in
the notes of Blumenbach, as it is for the most part
[Seite ii] strictly relevant to the subject matter of the text.
The additional notes of Mr. Lawrence, which, in
the edition of 1807, were annexed en masse to the
end of each chapter, have, in this edition, been
printed in a distinct type at the end of each para-
graph of the text which they are designed to illus-
trate.

Of the new matter, part has been introduced by
the author in editions of this Manual, subsequent to
that translated in 1807, and part has been annexed
to, or incorporated with the notes of Mr. Lawrence
by the present editor.

The works of the more recent physiologists and
comparative anatomists, especially those of Cuvier,
Blainville, Rudolphi, Carus, Meckel, Tiede-
mann,
and the Lectures of Sir E. Home, have been
diligently examined, with a view of supplying such in-
formation as the lapse of twenty years had rendered
necessary, in order to complete the plan of illustra-
tion adopted by the Translator. Many scarce and
valuable monographs have also been consulted for
that purpose. The information derived from these
sources is in some instances sufficiently distinguish-
ed, by the dates of the works cited, from former addi-
tions to this Manual, and, where there is no such dis-
tinction apparent on the face of the additional matter,
the Editor has not thought it necessary to point out
what has been added to the commentaries of Mr.
[Seite iii] Lawrence, preferring rather to place his own hum-
ble endeavours to increase the utility of the work
under the shelter afforded to them by the name of
the distinguished Translator.

To that eminent individual the Editor has now to
make his public acknowledgments for the mark of
friendship and confidence with which he has been
honoured, in being intrusted with the superintend-
ence of this publication. For the sake of the sci-
ence, indeed, he regrets that the numerous profes-
sional avocations of Mr. Lawrence have prevented
him from presenting the public with an improved
edition of this, one of his earliest literary produc-
tions; but he trusts, that as far as diligence and zeal
can supply the want of the Translator’s superintend-
ing care, the confidence which has been reposed in
him has not been entirely misplaced. Mr. Law-
rence’s
translation of this work was produced at
the outset of his professional life, at a time when a
knowledge of the German language might be consi-
dered a rare acquisition in this country; and his il-
lustrations of the text, even at this early period of
his career, afforded an earnest of that reputation
which he has since acquired by the splendour of
his physiological researches. Blumenbach has him-
self borne ample testimony to the merits of his com-
mentator; indeed it is as gratifying to remark the spi-
rit of candour and cordial approbation with which
[Seite iv] the labours of our distinguished countryman are
uniformly noticed by the continental writers, as it is
humiliating to reflect on the spirit of envy and ma-
lignity by which they have been assailed at home.
Envy and malignity, however, have done their
worst; it may be said rather that they have had the
effect of establishing the fame of Mr. Lawrence,
and of placing, beyond all competition, his claims
to the highest rank in his profession.

The Editor cannot conclude these observations
without expressing his acknowledgments to Mr.
Clift, the conservator of the Hunterian Museum, for
the great facilities he has afforded him in the prose-
cution of inquiries connected with this publication.
The value of the Hunterian Museum, with a view
to any practical advantage that can be derived from
it in physiological or pathological investigations, is
indeed greatly diminished by the want of a digested
catalogue of its contents. This want will, it is to
be hoped, be speedily supplied; in the mean time
nothing is better calculated to diminish the incon-
veniences resulting from it, than the urbanity, and
the readiness to afford information, which are dis-
played on all occasions by the present conservator.

William Coulson.

59, Aldersgate Street,

Oct. 1, 1827.

THE AUTHOR’S PREFACE
TO
THE FOURTH EDITION.

[Seite v]

I was first led, both by inclination and by the nature
of my professional pursuits, to devote the greater
portion of my time to the study of physiology, or the
foundation of medical science, as it has been termed
by Zimmermann, and to natural history, or the ma-
teria prima philosophiae,
as it has been called by Ba-
con.
I soon became convinced, and experience has
confirmed my conviction, that Haller was right
when he said of comparative anatomy, that it had
thrown more light upon physiology than even the
dissection of the human subject; an opinion which
has been further sanctioned by the authority of Leib-
nitz,
who has declared comparative anatomy to be
the soul of that branch of knowledge which is de-
dicated to the history of the animal kingdom. If I
[Seite vi] may venture to believe that I have not laboured in
vain in these two departments of science, the suc-
cess of my efforts is to be attributed to the collateral
assistance which I have derived from comparative
anatomy. As I may at least claim the merit of
having been the first to deliver lectures annually on
this subject, in Germany, and of having by these
means excited a taste for the science, and a zeal to
contribute to its advancement; so I trust that this
edition of my Manual, the first work of the kind
which has ever appeared on comparative anatomy,
as applied to the whole animal kingdom, will fur-
ther facilitate the study, and render it more univer-
sally useful. I have the more reason to think that
my readers will approve the plan of this work, as it
is, in fact, the same which I have pursued in my
elementary treatises on physiology and natural his-
tory; and which, from the various advantages it com-
bines, has been found best calculated to afford faci-
lities to students.

To give effect to such a plan it was necessary to
make a judicious selection from the vast mass of
materials which have been accumulated by the la-
bours of comparative anatomists. This I have en-
deavoured to accomplish, while at the same time I
have kept in view the application of the science to
physiology and natural history, and have occasion-
ally interspersed a few remarks illustrative of these
[Seite vii] branches of knowledge. It is evident that a minute
description of the muscles, vessels, nerves, &c.,
of the various classes of animals, could not be
comprised within the limits which I have prescribed
to myself. Comparative Osteology, however, de-
serves a more detailed examination, for the skele-
tons of red-blooded animals are not only intimately
connected with the rest of their anatomical struc-
ture, but also with their form, economy, and peculiar
habits.

To domestic animals, and to such as the sports of
the field bring most frequently under our notice, I
have paid particular attention; partly, because such
animals are most easily procured for dissection, and
partly on account of the great interest which is
likely to be taken in a correct knowledge of their
structure. With regard to foreign animals, I have
uniformly adverted to their most striking peculiari-
ties.

I have carefully cited my authorities for such
facts as I have not myself had an opportunity of
verifying; availing myself, in such cases, partly of
the best engravings which have been published, and
partly of the best monographs, and papers which
have appeared on the subject of comparative anato-
my in periodical collections; so that I have scarce-
ly omitted to notice a single author who has contri-
buted any thing of importance, and the notes to this
[Seite viii] Manual furnish a complete synopsis of the literature
of the science.

I have devoted a large portion of the work to the
classes of warm-blooded animals, as those in which
readers, whose time will not admit of extended in-
vestigation, will take the greatest interest. I have
not, however, neglected the classes of cold-blooded
animals, and the two last classes of the Linnaean
system, having generally explained the comparative
anatomy of the invertebrated animals, by an exam-
ple or two taken from each class.

To such authorities as the large systematic works
of Blainville, Carus, Cuvier, Geoffroy, Meck-
el, Rudolphi, Tiedemann,
and Treviranus, I
now, to avoid frequent repetition, refer once for all.
The same observation applies to the engravings
given by some of these writers, and especially by
Cuvier and Carus, as well as to the masterly mo-
nographs of Bojanus, Cuvier, Home, Spix,
Tiedemann,
&c., and to the copious additional
notes
with which the celebrated Lawrence has
enriched his translation of this Manual.*

I shall scarcely be expected to offer any apology
[Seite xix] for not having translated many well known technical
Latin terms, the translation of which would, in fact,
have rendered the things signified less intelligible;
nor is it, I trust, necessary for me to enlarge on the
numerous additions and improvements by which
the utility of the work has been increased in this
edition.

J.F. Blumenbach.
Gottingen,
March 31, 1824.

[[x]]

INTRODUCTION.*

[Seite xi]

Anatomical structure is the natural foundation
on which a systematic arrangement of the different
classes and species which compose the animal king-
dom may be established. Aristotle has adopted
to a certain extent this basis of classification; but it
is evident that no great advances could be made by
the ancients in a branch of knowledge, which pre-
supposes an intimate acquaintance with the struc-
ture and organization of animals. No attempt at
classification before the time of Linnaeus has any
pretensions to the name of a system affording accu-
rate criteria for distinguishing the different classes
of animals. The classification of Linnaeus, which
is adopted with some modifications by Blumenbach
in the following work, is founded on the observation
[Seite xii] of differences of structure in the organs of circula-
tion in such animals as possess a cardiac system.

Mammalia, viviparous

Birds, oviparous
{ Heart furnished with two
ventricles, two auricles;
blood warm and red.
Amphibia, respiring by
lungs
Fishes, breathing by
gills
{ Heart furnished with one
ventricle and one au-
ricle; blood cold and
red.
Insects, furnished with
antennae
Vermes, furnished with
tentacula

} Sanies cold and colour-
less.

Animals may be divided into two great families;
the first family possessing vertebrae and red blood;
the second without vertebrae, and most of them with
white blood. The former have always an internal
articulated skeleton, of which the chief connecting
part is the vertebral column. The anterior part of
this column supports the head; the canal which
passes from one end of it to the other incloses the
common fasciculus of the nerves; its posterior extre-
mity is most frequently prolonged, in order to form
the tail, and its sides are articulated with the ribs,
which are seldom wanting. None of this family of
animals has more than four limbs, some of them
have two only, and others have none.

[Seite xiii]

The brain is inclosed in a particular osseous ca-
vity of the head, called the cranium. All the nerves
of the spine contribute filaments to form a nervous
cord, which has its origin in the nerves of the cra-
nium, and is distributed to the greater part of the
viscera.

The senses are always five in number. There are
always two eyes, moveable at pleasure. The ear
has always at least three semicircular canals. The
sense of smell is always confined to particular cavi-
ties in the fore part of the head.

The circulation is always performed by one fleshy
ventricle at least; and where the ventricles are two
in number, they are always close together, forming a
single mass. The absorbent vessels are distinct from
the sanguiferous veins.

The two jaws are always placed horizontally, and
open from above downwards. The intestinal canal
is continued without interruption from the mouth to
the anus, which is always placed behind the pelvis,
that is, behind the circle of bones which affords a
fixed point for the posterior extremities. The in-
testines are enveloped within a membranous sac,
termed peritonaeum. There is always a liver and a
pancreas, which pour their secretions into the cavity
of the intestines; and there is always a spleen,
within which part of the blood undergoes some pre-
paratory change before it is sent to the liver.

[Seite xiv]

There are always two kidneys for the secretion of
urine, placed on the two sides of the spine, and
without the peritonaeum. The testicles also are
always two in number. There are always two bo-
dies called atrabiliary capsules, placed over the kid-
neys; the use of them is unknown.

Animals with vertebrae are subdivided into two
classes, one of which is warm-blooded, and the
other cold-blooded.

Warm-blooded vertebrated animals have always
two ventricles and a double circulation. They re-
spire by means of lungs, and cannot exist without
respiration. The brain almost always fills the cavity
of the cranium. The eyes are covered with eye-
lids. The tympanum of the ear is sunk within the
cranium; the different parts of the labyrinth are
completely inclosed within bone; and besides the
semicircular canals, the labyrinth contains the coch-
lea, with two scalae, resembling the shell of the snail.
The nostrils always communicate with the throat,
and afford a passage for the air in respiration. The
trunk is furnished with ribs, and almost all the
species of this branch of animals have four limbs.

Cold-blooded vertebrated animals resemble one
another more by their negative than their positive
characters. Many of them are destitute of ribs;
some of them are totally destitute of limbs. The
brain never fills the whole cavity of the cranium.
[Seite xv] The eyes seldom have moveable eyelids. The tym-
panum of the ear, when present, is always close to
the surface of the head; it is often absent, as are
likewise the ossicula auditus; the cochlea is always
wanting. The different parts of the ear are not
firmly attached to the cranium; they are often
loosely connected to it in the same cavity as the
brain.

Each of these two branches is subdivided into
two classes.

The two classes of warm-blooded animals are the
Mammalia and Birds.

The Mammalia are viviparous, and suckle their
young with milk secreted by the mammae. The fe-
males have consequently always the cavity termed
uterus with two cornua, and the males have always
a penis.

The head is supported on the first vertebra by
two eminences. The vertebrae of the neck are ne-
ver less than six, nor more than nine. The brain
has a more complicated structure than in other
animals, and contains many parts which are not to
be found in the other classes, such as the corpus
callosum, fornix, pons, &c.

The eyes have two eyelids only. The ear con-
tains four small bones, articulated together, and has
a spiral cochlea. The tongue is quite soft and
fleshy. The skin is covered entirely with hairs, in
[Seite xvi] the greatest number, and in all it is covered par-
tially.

The lungs fill the cavity of the chest, which is
separated from the abdomen by a fleshy diaphragm.

There is one larynx only, situated at the basis of
the tongue, and completely covered by the epiglottis,
when the animal swallows.

The lower jaw only is moveable; both jaws are
covered with lips.

The biliary and pancreatic ducts are inserted
into the intestinal canal at the same place. The
lacteal vessels convey a white milky chyle, and pass
through a number of conglobate glands, situated at
the mesentery. A membrane, called omentum, sus-
pended from the stomach and adjacent viscera, co-
vers the fore part of the intestines. The spleen is
always upon the left side, between the stomach,
ribs, and diaphragm.

Blumenbach establishes the following orders in
this class:*

Ordo I. Bimanus. Two handed.

II. Quadrumana, four-handed animals: having a
separate thumb capable of being opposed to [Seite xvii] the other fingers, both in their upper and lower
extremities, teeth like those of man, except that
the cuspidati are generally longer.

III. Chiroptera.

The fingers of the fore feet, the thumb excepted,
are, in these animals, longer than the whole body;
and between them is stretched a thin membrane for
flying. Hence they are as little capable of walking
on the ground as apes, with their hands, or sloths,
with their hooked claws, which are calculated for
climbing.

IV. Digitata.

Mammifera, with separate toes on all four feet.
This order contains the greatest number of genera
and species, and is therefore conveniently divided,
according to the differences of the teeth, into three
families, glires, ferae, and bruta.

V. Solidungula (Solipeda, Cuv.).

A single toe on each foot, with an undivided
hoof. Large intestines, and particularly an enor-
mous coecum. Incisors in both jaws.

[Seite xx]

VI. Bisulca (Pecora).

These are the ruminantia of Cuvier, their hoof is
divided. No incisors in the upper jaw. Stomach
consisting of four cavities. Rumination of the food.
Long intestines.

VII. Multungula (Belluae).

Animals of an unshapely form, and a tough and
thick hide; whence they have been called by Cu-
vier
pachydermata (from παχυς thick, and δερμα skin).
They have more than two toes; incisors in both
jaws, and in some cases enormous tusks.

VIII. Palmata.

Mammifera with webbed feet, the genera being
[Seite xxi] divided (as in the order Digitata) according to the
forms of the teeth into three families:

(A) Glires. (B) Ferae. (C) Bruta.

IX. Cetacea.

Whales living entirely in the sea, and formed like
fishes; breathe by an opening at the top of the head,
called the blowing-hole, through which they throw
out the water, which enters their mouth with the food.
[Seite xxii] Smooth skin covering a thick layer of oily fat. No
external ear. A complicated stomach. Multilobu-
lar kidneys; larynx of a pyramidal shape, opening
towards the blowing hole. Testes within the abdo-
men. Mammae at the sides of the vulva. Bones of
the anterior extremity concealed and united by the
skin, so as to form a kind of fin.

Cuvier distributes the class mammalia into three
grand divisions:

1. Those which have claws or nails, (mammifères à
ongles
) including the following orders: bimana,
quadrumana, chiroptera, plantigrada, carnivora, pe-
dimana, rodentia, edentata, tardigrada.

2. Those which have hoofs (mammif. à ongles) in-
cluding the pachydermata, ruminantia, and soli-
peda.

3. Those which have extremities adapted for
swimming (mammif. à pieds en nageoire). Amphibia
and cetacea.

BIRDS.

Birds are oviparous. They have only one ova-
rium and one oviduct, in which they differ from other
[Seite xxiii] oviparous animals. The head is supported on the
first vertebrae of the neck by a single eminence. The
vertebrae of the neck are very numerous, and the
sternum very large. The anterior extremities are
used for flying, and the posterior for walking.

The eyes have three eyelids. There is no exter-
nal ear; the tympanum contains only one bone, and
the cochlea is a cone slightly curved. The tongue
has a bone internally. The body is covered with
feathers. The lungs are attached to the ribs. The
air passes through the lungs in its way to the air-
bags, which are dispersed throughout the body.
There is no diaphragm. The trachea has a larynx
at each end, and the upper one has no epiglottis.
The upper mouth consists of a horny bill without
lips, teeth, or gums, and both mandibles are move-
able.

The pancreas and liver send out several excretory
ducts, which enter the intestines at different places.
The chyle is transparent, and there are no mesenteric
glands nor omentum. The spleen is in the centre
of the mesentery. The ureters terminate in a cavity
called the cloaca, which also affords an exit to the
solid excrement and to the eggs. There is no uri-
nary bladder.

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

[Seite xxiv]

(A) Land Birds.

[Seite xxvii]

(B) Aquatic Birds.

The two classes of cold-blooded vertebral animals
are the

AMPHIBIA AND FISHES.

The animals of the former class differ from one
another in many very essential particulars, and have
not so many characters in common as the other
classes. Some of the reptiles walk, some fly, some
swim, many can only creep. The organs of the
senses, and particularly the ear, differ almost as
much as the organs of motion; none of the reptiles,
however, have a cochlea. The skin is either naked
or covered with scales. The brain is always very
small. The lungs are in the same cavity with the
other viscera; there are no air-bags beyond the
lungs, hut the cells of these organs are very large.
There is but one larynx, and no epiglottis. Both
the jaws are moveable. There are neither mesente-
[Seite xxix] ric glands, nor omentum. The spleen is in the centre
of the mesentery. The female has always two ova-
ria and two oviducts. There is a bladder.

The class of reptiles, in the arrangement of Cuvier,
corresponds to the orders of reptiles pedati, and ser-
pentes apodes, belonging to the class of amphibia
in the Systema Naturae of Linnaeus.

Fishes respire by means of organs in the shape of
combs, placed at the two sides of the neck, between
which they force water to pass. They have, conse-
quently, neither trachea, larynx, nor voice. The
body is formed for swimming. Besides the four
fins, which correspond to the limbs, they have ver-
tical ones upon the back, under the tail, and at its
extremity; but they are sometimes wanting.

The nostrils are not employed in respiration.
The ear is quite hid within the cranium. The skin
is naked, or covered with scales. The tongue
is osseous. Both jaws are moveable. There are
often coeca in place of the pancreas. There is a
bladder and two ovaria.*

[Seite xxxi]

The animals destitute of vertebrae have less in
common, and form a less regular series than the ver-
tebrated animals. But, when they have hard parts,
these are generally placed on the outside of the
body, at least when articulated; and the nervous
system has not its middle part inclosed within a ca-
nal of bone, but loosely situated in the same cavity
with the other viscera.

The brain is the only part of the nervous system
which is placed above the alimentary canal. It
sends out two branches, which encircle the oesopha-
gus like a necklace, and which afterwards unite and
form the common fasciculus of the nerves.

None of the animals without vertebrae respire by
cellular lungs, and none of them have a voice.
Their jaws are placed in all kinds of directions, and
many of them have only organs of suction. None
of them have kidneys, or secrete urine. Those
among them which have articulated members have
always six at least.

(A) Cartilaginous Fishes.

(B) Bony Fishes, divided according to the situa-
tion of their fins.

The invertebral animals were distributed by Lin-
naeus
into two classes, insects and worms (vermes).
The anatomical 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 Cu-
vier,
have succeeded in establishing such striking
and important differences in their formation, that a
subdivision of the Linnaean classes becomes indispen-
[Seite xxxv] sably necessary. The insects of Linnaeus are di-
vided into crustacea and insecta; and the vermes of
the same author form three classes, viz. mollusca,
vermes,
and zoophyta.

The Insects form the third class.

In their perfect state they have, like the crus-
tacea, articulated limbs and antennae. Most of them
have also membranous wings, which enable them to
fly. All these last pass through several metamor-
phoses, in one of which they are quite destitute of
the power of motion. All of them have a nervous
system similar to that of the crustacea; but insects
have neither heart nor blood-vessels, and respire by
tracheae. Not only the liver, but all the secreting
organs are wanting, and their place is supplied by
long vessels, which float loosely in the abdomen.
The form of the intestinal canal is often very differ-
ent in the same individual, in its three different
states.*

The animals which resemble the larvae of insects,
and have, like them, the medullary cord knotted,
may be placed in the same class with insects, though
they undergo no metamorphosis; but there are some
of that number which have distinct sanguiferous
[Seite xxxvi] vessels, and which must be arranged in a separate
class, intermediate between the mollusca, crustacea,
and insects. To this class belong earth-worms and
leeches.

[Seite xl]

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 organi-
zation as the latter; so that they are sometimes ar-
ranged among the zoophytes. The external worms
have a nervous chord possessing ganglia, an elon-
gated body composed of rings; and having no dis-
tinct head. There are no members. Circulating ves-
sels, but no heart. No nerves have been discovered
in the intestinal worms.

The class of worms comprehends some of the ge-
nera arranged by Linnaeus among the vermes intes-
tina,
such as the lumbricus, gordius, thrudo; some
of the genera placed by the same naturalist among
the vermes mollusca, such as the aphrodita, nereis, te-
rebella,
and lastly some genera included in his order
of vermes testacea, such as the serpula dentalium.

The class of mollusca comprehends the greater
part of the animals which Linnaeus has arranged in
the two orders of mollusca and testacea, in the class
of vermes; such as the sepia, limax, ascidia, helix, os-
trea, patella, pholas, teredo,
&c.

The body of the mollusca is fleshy, soft, and with-
out articulated members, though sometimes contain-
ing hard parts internally, and sometimes covered
completely by hard shells. They have arterial and
venous vessels, within which the blood undergoes a
true circulation.

They respire by branchiae. The brain is a distinct
mass, from which the nerves and medulla oblongata
proceed. There are ganglia in different parts of the
body.

The internal senses vary as to their number.
Some of the mollusca have the organs of sight and
hearing quite distinct, while others seem to be con-
fined to the senses of touch and taste. Many of
them can masticate their food; others have the power
of swallowing only.

They have a very large liver, which affords a great
quantity of bile. The organs of generation vary ex-
tremely.

[Seite xlii]

IV. Crustacea.

The body is covered with a hard crust in separate
pieces. There are articulated limbs, which are often
very numerous. The nervous system consists of a
long, knotted cord, from the ganglia of which pro-
ceed all the nerves.

The eyes are compound, hard, moveable. The
ears are very imperfect. For the sense of touch, the
crustacea have antennae and palpi, like insects. They
have a heart, arterial and venous vessels, and bran-
chiae for respiration. The jaws are transverse, strong,
and numerous. The stomach has teeth within. The
numerous coeca afford a brown liquor, which seems
to be in the place of bile. The penis is double, and
there are two ovaria.*

V. Corallia.

They inhabit certain immovable dwellings which,
in most cases, are of a stony consistence, and are
called corals.

[Seite xlv]

VI. Zoophyta.

The class of Zoophytes correspond to the Zoo-
phyta
and lythopyta of Linnaeus, but also include
some of the vermes mollusca, such as the echinus,
asterias, holothuria, actinia, medusa,
together with
the genus sipunculus from the vermes intestina.

[Seite xlvi]

Outline of Cuvier’s Classification of Animals; with
Examples of Species belonging to each Division.

I. VERTEBRATA.

1. mammalia.

2. aves.

[Seite xlvii]

3. reptilia

4. pisces.

II. MOLLUSCA.

III. ARTICULATA.

1. annelides, or vermes.

[Seite xlviii]

2. crustacea.

3. arachnida.

4. insecta.

IV. ZOOPHYTA.

TABLE OF CONTENTS.

[Seite xlix]

COMPARATIVE OSTEOLOGY.

CHAP. I.

Page

CHAP. II.

CHAP. III.

CHAP. IV.

CHAP. V.

CHAP. VI.

[[l]]

CHAP. VII.

CHAP. VIII.

CHAP. IX.

CHAP. X.

CHAP. XI.


ON THE VITAL FUNCTIONS.

CHAP. XII.

CHAP. XIII.

CHAP. XIV.

[Seite lii]

CHAP. XV.


THE ANIMAL FUNCTIONS.

CHAP. XVI.

CHAP. XVII.

CHAP. XVIII.

[Seite liii]

CHAP. XIX.

CHAP. XX.

CHAP. XXI.

CHAP. XXII.

[Seite liv]

THE GENERATIVE FUNCTIONS.

CHAP. XXIII.

CHAP. XXIV.

CHAP. XXV.

CHAP. XXVI.

CHAP. XXVII.

COMPARATIVE OSTEOLOGY.

[[lv]] [interleaf]

COMPARATIVE OSTEOLOGY. CHAPTER I.
ON THE BONES OF ANIMALS IN GENERAL.

[Seite 1]

§ 1. Red-blooded animals only possess a true skeleton;* to
which their bones are connected, and on which the general
form, as well as the greater or less flexibility of the body de-
pends. 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 in several mammalia; the bony ring in the
sclerotica of birds; the clavicular bones of some mammalia;
to which instances may be added the whole anterior extre-
mity in such mammalia as possess no clavicles; and the abdo-
minal fins of fishes, which correspond to the posterior extremi-
ties of other animals.

§ 2. The ordinary white colour of the bones has several
gradations, which are sometimes observable in the different
parts of the same bone; as in the grinding teeth of the ele-
[Seite 2] phant; a section of which, or of the tooth of any other
herbivorous animal, as the horse, ox, &c. shews that its sub-
stance contains parts differing considerably in appearance.
Besides the processes of enamel, which are intermingled
throughout with the bone, there are two kinds of osseous
structure of different colours. In some few genera the whole
bony structure is of a different colour;* thus, in the garpike,
(esox belone) the bones are green; and in some varieties of
the common fowl they approach to a black colour.

§ 3. The structure of the bones is subject to still greater
variations; which occur in the different bones of the same
skeleton, as well as in the whole skeleton of particular classes
and orders. Instances may be observed in the dry and brit-
tle texture 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.

Ossification does not go on with equal rapidity in all animals, nor
in all the bones of the same animal. Thus, the ossification of the
internal ear of man, and other mammalia, is completed before any
other parts; and the bone formed at this early period surpasses all
others in 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
hardness equal to those of marble. Its section presents a homogene-
ous appearance, without the least vestige of fibres, cellular texture,
or vessels.

Bones are slow in their 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 as the shark, skate, sturgeon, and all those fishes which, from
[Seite 3] this circumstance, have been denominated cartilaginous, or chon-
dropterygii.
Although the bones of other fishes, of reptiles, and
serpents, acquire 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 quadrupeds 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 sur-
face. In the jaw and the ribs particularly, the fibres may be
loosened by maceration, and become very obvious.

The bones of birds consist of a thin, firm, elastic substance, formed
of layers apparently fastened on each other. They are almost uni-
versally hollow; but their cavities, which never contain marrow, are
filled with air. This organization unites the advantages of lightness
and strength.

The bones of reptiles and fishes have a very homogeneous appear-
ance, the earthy matter and the gelatine appearing to be uniformly
mingled: this is more strikingly marked, as we approach to the car-
tilaginous fishes, where the gelatine predominates, 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 horn of the stag is a real bone, as appears both from its tex-
ture, and its component elements. Its outer part is hard, compact,
and fibrous; the internal substance is reticulated, but very firm;
and possesses neither cavities nor marrow. It is liable to precisely the
same diseases as other bones; thus, we sometimes find exostoses
formed upon its surface by the extravasation of its calcareous mat-
ter, while in other instances, from a deficiency of this component
part, it is rendered light and porous.

The shells of the testaceous animals are formed of a calcareous
substance, which is sometimes laminated; sometimes as hard and
dense as marble. This substance 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 uniformly expanded through the animal substance.

The layers of the shell are formed successively, as the animal in-
creases 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 surface of the animal?
Reaumur 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 repaired, when no artificial obstacle im-
peded the effusion of fluids from the surface. This experiment
seems to prove that the shell is formed by deposition from the body
[Seite 4] of the animal; but there is an argument equally strong in favour of
the existence 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 fetid and bitter 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 ar-
terial and absorbing vessels.

Crustaceous animals (crab, lobster, &c.) have a skeleton which sur-
rounds and contains their soft parts, and which serves at the same
time the purposes of a skin. When it has attained its perfect con-
sistence, it grows no more; but as the soft parts still increase, the
shell separates, and is detached, 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 interior of their body.
The common cuttlefish (sepia officinalis) has a white, firm, and calca-
reous 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 connexion with any soft part,
whence it appears completely as a foreign body: no vessel or 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 re-
sembles that of a leaf, except that it is larger; and sometimes that of
a sword-blade. This structure must grow like shells, by the simple
addition of successive layers.

§ 4. Excepting the crown of the teeth, bones are univer-
sally covered with periosteum; and for the most part they
contain marrow* internally; which varies much in consistence,
being fluid in whales.

§ 5. Bones are formed by the ossification of original carti-
lages; the teeth being again for the most part excepted.
Ossification commences earlier, and proceeds more rapidly in
viviparous, than in oviparous animals. This fact appears at
least from comparing the incubated bird with the foetus of
mammalia. It is well known, that the incubation of the chick
occupies twenty-one days. The commencement of ossifica-
[Seite 5] tion is not perceptible before the beginning of the ninth day;
which corresponds with the seventeenth week of human preg-
nancy. In the human embryo the first points of ossification
may be discerned in the seventh or eighth week after concep-
tion, certainly not in the third or fourth week, as some anato-
mists have supposed. These facts shew how little confidence
can be placed in that remark of Haller’s, which concludes his
otherwise masterly observations on the formation of the bones
in the incubated chick: Quae de pullorum ossibus demon-
stravimus, ea etiarn de aliis animantium classibus vera erunt,
et de ipso demum homine:
‘“What I have proved as to the
bones of the chick, will hold good with respect to those of
other classes of animals, and of man.”’ Of the mammalia, it is
to be observed, that many points in the formation of the
bones are completed sooner in quadrupeds than in man. An
example occurs in the closure of the fontanelles. I have found
these openings of considerable size in young foetuses of the
ferae and pecora, but could hardly discern any trace of them
at the time of birth; nothing at least which could be com-
pared 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 fontanelles, is only required to
facilitate the birth of the human foetus.

Professor Florman, of Sund, however, denies altogether
the appearance of the fontanelles in the skulls of young ani-
mals, according to Weber’s and Mohr’s Natur-histor. Reise
durch einen Theil Schwedens,
p. 35. But I have found them
in many of the digitata, as for instance in the new born lepus,
of very considerable size.

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 present place.

The bones and teeth of red-blooded animals consist chiefly of
phosphate of lime, deposited in the interstices of an animal sub-
stance; which, when freed from the earthy matter by the immersion
[Seite 6] of the bone in an acid, approaches in its consistence to cartilage.
This is completely dissolved by boiling in a close vessel, and is
thereby proved to consist of gelatine. A small quantity of carbonate
of lime is mixed with the phosphate; and hence effervescence arises
when a bone or tooth is subjected to the action of acids.

The horn of the stag is bone, containing a large proportion of ge-
latine.

The bones of fishes contain phosphate of lime; but the animal
substance exists in very large proportion, particularly in those which
are called cartilaginous, 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 phosphate, 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 substance. When immersed in acid, a
rapid effervescence ensues. Some of them, which are very hard in
their texture, and have an enamelled surface, contain so little animal
matter, that they are 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. the oyster, muscle,
&c.) contain a much larger proportion. When these have been ma-
cerated in acid, a gelatinous substance remains, consisting of several
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 consists, like shells, of various mem-
branes, 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 chemist 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 II.

CHAPTER II.
ON THE SKELETON OF MAMMALIA.

[Seite 7]

§ 6. The form of the different mammalia, particularly the
four-footed ones,* varies considerably; and their skeletons
must be marked by corresponding differences. Yet these va-
rieties may be included, at least for the greatest part, under
the following peculiarities; which serve to distinguish their
skeletons from those of birds.

The skeletons of mammalia
possess;
Those of birds are distin-
guished by;
1. A skull with genuine su-
tures (at least with very few
exceptions; as perhaps the
elephant, and the duck-billed
animal, ornithorhynchus).
1. A skull which has not
real sutures.
2. Jaws furnished with
teeth; except the ant-eaters,
the manis, the duck-billed ani-
mal,§ the balaena (whale).
2. A bill without teeth.
[Seite 8]
3. An immoveable upper
jaw.
3. A moveable upper jaw:
There are some exceptions,
viz. the rhinoceros bird.
4. An os intermaxillare.
(For the probable excep-
tions, see § 15.)
4. No os intermaxillare.
5. Two occipital condyles. 5. A single occipital con-
dyle.
6. Seven cervical vertebrae;
except the three-toed sloth,
and some cetacea.
6. More than seven cervi-
cal vertebrae.
7. Moveable dorsal verte-
brae.
7. Dorsal vertebrae little
moveable, and for the most
part motionless.
8. A pelvis closed in front;
except the ant-eaters; which
have it open; and the cetacea,
which have none.
8. A pelvis open anteriorly,
Except the ostrich.
9. True clavicles in a few
genera only.
9. Clavicles constantly, and
almost as universally the fork-
like bone.
*

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

[Seite 9]

§ 8. The well known division of the bones of the head into
those of the cranium and of the face, is convenient for point-
ing out the remarkable proportions of relative magnitude in
the two divisions.* Compare, for instance, the skull of the
kangaroo (didelphis gigantea) with that of the opossum, (did.
marsupialis
) or the skull of the dolphin (delphinus delphis)
with that of the white whale (physeter macrocephalus).

§ 9. The number of proper bones of the cranium is, on the
whole, the same as in the human subject. The os frontis,
however, in most of the horned animals, is composed of two
equal portions; in many of these the two parietal bones are
consolidated into one, and in others they are united to the oc-
ciput. Some of the digitata have a peculiar flat bone situated
transversely between the parietal and occipital bones.

§ 10. As the forehead of man is peculiarly distinguished
by the beauty of its convex superficies, so is that of many of
the quadrumana, as the larger animals of the monkey tribe,
papio mormon, &c. by the large flat triangular surface into
which it is compressed, and the sides of which converge from
the processus malares at the external angles of the orbits, ob-
liquely backwards, towards the crista occipitalis.

[Seite 10]

The sphenoid bone is often divided into two parts in the quad-
rumana;
one of these forms the lesser alae, and anterior clinoid
processes; the greater alae, the posterior clinoid processes, and ba-
silar 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, hippopo-
tamus,
and horse.

The frontal and parietal bones of the elephant become consoli-
dated, 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 dis-
cerned. The parietal, occipital, and temporal bones are likewise
joined at an early period 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, which is seldom
completely united in the dog, cat, and civet. The cavity of the
tympanum is also separated in the rodentia, and the os frontis re-
mains divided into two portions. In the cetacea the parietal bones
are joined at a very early period to the occipital and temporal, so
that the five bones form only one. The bone of the ear is always
separated, and is merely attached to the cranium by soft parts. In
the elephant this bone is also distinct and separated from the tempo-
ral.

The cranium of the mammalia possesses the same fossae at its basis,
as are found in the human subject: they are however much shal-
lower; 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 cavities 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 de-
viates 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 optic foramina of the elephant commence from one canal,
which receives the two optic nerves.

The foramen rotundum is sometimes absent, its place being sup-
plied by the spheno-orbitar fissure, (foramen lacerum) e.g. in the
elephant and horse. The foramen ovale is also frequently wanting;
being included perhaps in the space left between the petrous por-
[Seite 11] tion of the temporal bone, and the body of the sphenoid. This
latter opening does not exist in the genus simia, nor in the carni-
vorous 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.

The structure of the cranium presents a very remarkable singula-
rity 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, communicating with the throat by
means of the eustachian tubes, and filled with air, instead of the
bloody or medullary substance which occupies the diplöe of ani-
mals. The use of this structure in increasing the surface for attach-
ment of those large muscles which belong to the lower jaw, pro-
boscis, and neck; and in augmenting the mechanical power of these
muscles by removing their attachments to a greater distance from
the centre of motion, has been very ingeniously explained by Camper,
(Oeuvres, tom. ii.). 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 ge-
neral, and particularly those which pervade the cranium in the
ostrich, eagle, and owl, present examples of a similar formation, at-
tended with the same uses, viz. those of increasing the bulk and
strength of the bone, and diminishing its weight.

§ 11. A principal variation in the form of the cranium arises
from the size and direction of the crista occipitalis, which
bears a determinate proportion to the strength of the jaws.
It is wanting in most monkeys, but is very large in the baboon
of Borneo.* The longitudinal crista is very strongly express-
ed in the badger; and the transverse ridge is remarkable in
the beaver, and both in the opossum. Between the arched
sides of the upper part of the cranium in the elephant lies a
broad and deep impression, with a small longitudinal crista at
its bottom.

There is a considerable difference in this respect between
the various races of dogs: as between the pug-dog and that
of Newfoundland.

The crista occipitalis is a sharp, bony ridge, projecting from the
[Seite 12] upper and 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 order; 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
animals 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 discernible in most of the simiae. They occur
also in animals 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.

§ 12. The situation and direction of the great occipital fo-
ramen
are attended with remarkable variations in some in-
stances. Instead of being situated far more anteriorly, and for
the most part horizontally, as in the human subject,* (in which
indeed the anterior margin is sometimes higher than the poste-
rior) it is placed, in most quadrupeds, at the base of the cra-
nium, and obliquely, with the posterior border more or less
turned upwards. In some, indeed, its direction is completely
vertical; and in the marmot of the Alps its upper margin is
turned more forwards than the lower.

[Seite 13]

The variations in the situation of the occipital foramen are impor-
tant, when viewed in connexion 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.

Quadrupeds have the occipital foramen and condyles situated
farther back, in proportion as the face is elongated. That opening,
instead of being nearly parallel to the horizon, forms a considerable
angle with it; which, measured according to Daubenton, is of 90
degrees in the horse. The weight of the head in these animals 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
existence disputed in the human subject. This ligamentum nuchae, or
cervical ligament, arises from the spines of the dorsal and cervical
vertebrae, (which are remarkably 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 enormous 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 sup-
ported by four extremities. Their structure is by no means calcu-
lated, like that of man, for the constant maintenance 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
occipital foramen is only twice as far from the jaws as from the back
of the head, so that Daubenton’s angle is only 37°. It is somewhat
larger in the other species of simiae; and measures 47° in the lemur.

§ 13. The true sutures, which connect the individual bones
of the cranium, are generally less intricate, at least to outward
appearance, in quadrupeds than in man. Their indentations
are very strong and sharp in the horned pecora, for obvious
reasons; and the frontal bones are thick in the same animals.
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.
The ossicula wormiana are seldom seen in the crania of ani-
mals, yet I have specimens of these in the hare, and a young
[Seite 14] orang-outang; the sutures of the latter are remarkably ele-
gant. The observation, therefore, which Eustachius makes
(Ossium Examen, p. 173), concerning the sutures of apes,
namely, that ‘“they are always so obscure, as scarcely ever
to deserve the name of sutures,”’ must be understood with
some limitations.

§ 14. The general form of the cranium is most materially
influenced by the direction, and the various degrees of promi-
nence 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 os intermaxillare, which is inclosed
between the two upper jaw-bones. To determine this with
greater precision, Camper instituted the facial line, the appli-
cation of which is most minutely 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 intersect each other; but in different di-
rections from those of the French anatomist. A 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, proceeding from the convexity of the fore-
head, to the most prominent 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.

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 quadrupeds, which
we are hitherto acquainted with, whose crania differ extremely
in other respects, have one and the same facial line.

The two organs which occupy most of the face, are those of smell-
ing and tasting, (including those of mastication, &c.). In proportion,
[Seite 15] 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 volume 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, masti-
cating, &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 inferences from them; by which, in short, it reflects and
thinks. We shall find that animals partake in a greater degree of
this latter faculty, in proportion as the mass of medullary substance,
forming their brain, exceeds that which constitutes the rest of the
nervous system; or, in other words, in proportion as the organ of
the mind exceeds those of the senses. Since then, the relative pro-
portions of the cranium and face indicate also those of the brain,
and the two principal external organs, we shall not be surprised to
find that they point out to us, in great measure, the general charac-
ter of animals, the degree of instinct and docility which they possess.
Man combines by far the largest cranium with the smallest face;
and animals deviate from these relations in proportion as they in-
crease in stupidity and ferocity.

One of the most simple methods (though sometimes indeed insuffi-
cient,) 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 stupidity of the crane and
snipe has 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 acquires a particular air of intelligence,
and gains the credit of qualities which he does not in reality possess.
Hence the latter animal has been selected as the emblem of the
goddess of wisdom. The invaluable remains of Grecian art shew
that the ancients were well acquainted with these circumstances;
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° in the representa-
tion of men on whom they wished to bestow an august character,
and in the representations 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 angle is of chief
[Seite 16] importance in its application to the cranium of the human subject,
and of the quadrumana; as various circumstances affect the conclu-
sions which would result from employing it in other classes of mam-
malia. Thus in the carnivorous, and some of the ruminating animals,
in the pig, and particularly in the elephant, the great size of the fron-
tal 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 line 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 of the upper alveoli, and the convexity of the
cranium (whether the latter point be concealed by the face or not).

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

41
Ditto, inner ditto 30
Leopard; inner surface 28
Hare 30
Ram 30
Horse 23
Porpoise 25

In the 3d and 4th tables of Cuvier’s Tableau Elémentaire de l’His-
toire Naturelle,
the crania of several 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.

The mode of comparison instituted by Cuvier shews the relative
proportions of the cranium and face much more satisfactorily than
that of Camper. This learned naturalist makes a vertical section
of the skulls of different races of men, and the various classes of
animals, and then compares the relative proportion of the cavity of
the cranium to that of the section of the face. In the European the
area of the section of the cranium is 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 increases 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 carnivorous
mammalia,
the two parts are nearly equal. The face exceeds the cra-
nium in most of the other classes. Among the rodentia, the hare and
[Seite 17] 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 tri-
ple in the hippopotamus, and almost four times as large in the horse.
In reptiles and fishes, the cranium forms a very inconsiderable por-
tion 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 downwards, from the root of the
nose towards the foramen 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 ante-
rior one the longest. These proportions become still more consi-
derable in other mammalia.

§ 15. 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 intermaxillary bone,* which is in a manner locked be-
tween the former, and holds the incisor teeth 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 as have no incisor teeth at all, viz. the duck-
billed animal,
the Cape ant-eater, and the armadillo. It is
even found in those mammalia which are wholly destitute of
teeth, as the ant-eater and the proper whales. It is joined
to the neighbouring bones by sutures, which run externally by
the side of the nose and snout, and which pass, towards the
palate, close to the foramina incisiva.§ Its form and magni-
[Seite 18] tude vary surprisingly in several orders and genera of mam-
malia. It is small in many ferae, as also in the walrus (tri-
chechus
). In many of the glires* it is remarkably large, viz.
in the beaver and marmot. It is also large in the hippopo-
tamus, porpoise,
and cachalot, (physeter macrocephalus) and
particularly projecting in the wombat. Its form is very re-
markable in the ornithorhynchus, where it consists of two
hook-like pieces, joined by a broad synchondrosis.

The want of the os intermaxillare has been regarded as a chief
characteristic of the human subject; as one of the leading circum-
stances 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 consider, that the superior or facial surface
of the maxillary bones, so far from being marked by any suture,
[Seite 19] 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 it is wanting in man. The exceptions occur in the quadru-
mana. In addition to those which the author has stated, it may be
observed, that the head of an orang-outang, in the Hunterian Museum,
which possesses all the other sutures, wants those which separate
the intermaxillary bone. Tyson did not find this bone in his spe-
cimen of the animal, which was very young, (see his Anatomy of the
Pigmy
) and it did not exist in a cranium which was delineated by
Daubenton. I have also seen the crania of other monkeys, in which
the sutures were all perfect and distinct, although this bone was
wanting.

§ 16. The above-mentioned anterior palatine holes, or fora-
mina incisiva
are double in most mammalia, as in man. They
are much larger in quadrupeds than in the human subject:
in the pecora and the hare they are remarkably long and
broad.*

§ 17. There are remarkable impressions on the outer side of
the upper jaw of most pecora, near to 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 rumi-
nant animals.

§ 18. In the zygoma we observe several important diffe-
rences, immediately derived from the organs of mastication.
In many quadrupeds (especially the digitata and palmata,)
the processus malaris of the superior maxillary bone runs in a
long narrow process towards one similar in shape coming
from the temporal, so that it occupies the situation of the
malar bone in man. This bone is wedged in as a middle
piece between these two processes, has nothing to do with
the frontal, and consequently does not contribute to the for-
mation of the orbits. The zygoma is straight, and almost of
[Seite 20] a thread-like slenderness in the mole. It is of immense
strength, and includes a large space towards the cranium, for
lodging the powerful muscles which move the lower jaw, in
several carnivorous animals, as the tiger, and in some glires,
as the beaver. In the rat, and some others, it is convex
below; in the weasel, above. It is remarkable in the sloth
for a large descending process, which comes from the os
malae.*

The zygoma is wanting in the ant-eater, in which the temporal and
malar bones have only a slight projection instead of the usual zygo-
matic process. This circumstance is sufficiently explained by the
want of teeth, and the consequent want of mastication. The zygo-
matic 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 latter 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.

§ 19. The elephant possesses only a rudiment of the nasal
bones. In most apes, and even in the orang-outang, there is
a single, triangular, and very small nasal bone; in the rib-
faced baboon
(papio mormon) it is exceedingly long and nar-
row, and sinks between the long nasal processes of the superior
maxillary bones. In the greater number of true quadrupeds,
there are two ossa nasi, frequently of very considerable mag-
nitude. This is the case in the pecora and hare; also in the
horse, pig, &c. In the rhinoceros, the ossa nasi, which sup-
port the horn, are very soon consolidated together.

§ 20. Of the lacrymal bones also, (ossa unguis) there is
merely a rudiment in the elephant. These bones are stri-
kingly developed in the bisulca, especially in the antelope,
and still more remarkably in the opossum (didelphis marsu-
pialis
).

[Seite 21]

§ 21. The orbits differ very much in their direction, capa-
city, and depth. They have for the most part a lateral direc-
tion. In the simiae they are directed 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 mammalia.
In the pecora and solidungula they have a circular margin in
front; but the external wall is deficient behind. In most of
the ferae, and in 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 deserve the
name of orbit; viz. in the mole and ant-eater. Haller’s asser-
tion, 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 (lemures). See the delineation of
their crania in Fischer’s valuable work above quoted, Anatomy
of the Maki.
Frankfort, 1804, 4to.

The interval between the orbits is always smaller in the simiae than
in the human subject. In several of these, as in the monkeys, pro-
perly so called, the two orbits are separated at their posterior part by
a simple bony septum. In other mammalia 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, rodentia, edentata, and pachydermata) the os malae merely
contributes to the formation of the zygoma, without being connected
to the frontal or sphenoid 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 mar-
gin 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 integuments. Blumenbach’s Beschreibung der Knocken, p. 225,
note. The same observation holds good of the myrmecophaga didac-
tyla.
Ibid.

The organ of vision is present without exception, only in one class
of animals, namely, in birds. In the mammalia we have two instances
[Seite 22] of complete blindness, namely, in the blind rat (spalax typhlus, Pall.
Mus typhlus, L.
) and in a variety of the mole (chrysochlorus, sorex
aureus
). In both these animals a hairy curtain, in which there is no
fissure, is continued over the shrivelled eyes. Rudolphi, Physiologie,
vol. ii. p. 154.

§ 22. 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 posterior
rests on the os frontis;* 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 an-
telope,
or bony productions, as in the genus cervus, which in-
cludes animals of the deer kind. In the former, the external
table of the frontal bones is elongated into one process, and in
the ovis polycerata, into several. In the greater number of
these the frontal sinusses extend into the horny processes.
The antelopes have been in general excepted. But that this
exception does not hold good of all the species of this tribe,
appears from the horn of an antelope bubalis in my collection,
the bony process of which is hollow and connected with the
frontal sinusses. The external vascular surface of the pro-
cess secretes the horn, which covers it like a sheath. In
the stag kind (in the male only in most genera), the frontal
bone forms a short flattened prominence, from which the pro-
per 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. The little horns of the giraffe hold a
middle place between these two divisions. In their form,
structure, and permanent duration, they resemble the frontal
processes of the proper horns: in their hairy covering they
approach to the branches of the stag kind.

[Seite 23]

I have collected about twenty instances, from the mid-
dle of the sixteenth 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 resem-
ble 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
drawings, which I possess, by far too large for a hare.

The annual reproduction of horns constitutes, in many points
of view, one of the most remarkable phenomena of animal phy-
siology. It affords a most striking proof, 1st, of the power of
the nutritive process, and of the rapid growth which results
from this process in warm-blooded animals; for the horn of a
stag, which may weigh a quarter of a cwt. is completely form-
ed in ten weeks: 2ndly, of the remarkable power of absorption,
by which, towards the time of shedding the old horn, a com-
plete separation is effected of the substance, which was before
so firmly united with the frontal bone: 3rdly, of a limited du-
ration of life in a part of an animal, entirely independent on
the life of the whole animal, which in the stag extends to about
thirty years: 4thly, 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 dimensions when that process has ceased: 5thly,
of a peculiar sympathy, which is manifested between the growth
of the horns and the generative functions; for castration, or
any essential injury of the organs of generation, impedes the
growth, alters the form, or interrupts the renewal of the
horns.* It has also been asserted, but without a sufficient
[Seite 24] proof hitherto, that injuries of the newly formed horn render
the stag impotent for some time.

The word horn, which is frequently applied in English to the ant-
lers
of the deer kind, as well as to the real horns of other genera,
would lead to very erroneous notions on this subject. The antler 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. 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 be-
tween the process of the frontal bone and the antler. This becomes
more and more distinctly marked, until the connexion is entirely de-
stroyed.

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 struc-
ture of the part at this time is soft and cartilaginous; it is immedi-
ately invested 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 projecting 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 periosteum 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, always increasing in size.

The horn is shed in the spring, and re-produced in the summer;
during the interval the male and female abstain from copulation.
When the rutting season, which lasts three weeks, commences, large
troops of the males and females re-assemble, and continue together
during the winter.

§ 23. 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 peculiar 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 approach-
[Seite 25] ing the nearest to him in this respect.* The same bone is fur-
ther distinguished 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 si-
tuated in the same straight horizontal line in the ferae; their
form is cylindrical; and they are completely locked in an elon-
gated glenoid cavity, whose margins are so extended before
and behind the condyle, that all rotatory motions are rendered
impossible, and hinge-like movements only allowed. This
structure is most strikingly exemplified in the badger, where
the cylindrical condyles are so closely embraced by the mar-
gins 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 ele-
phant
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 into contact by the free
lateral motion, which takes place in rumination. The two con-
dyles lie parallel to each other in a longitudinal direction in
many glires; viz. in the hare, where (as in the ant-eater) 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 di-
rectly backwards.

There are, on the whole, few other bones in the skeleton of
mammalia, of such various forms as the lower jaw. The most
anomalous formation of this bone is the shovel-like surface of
its anterior part in the duck-billed animal: to which may be
[Seite 26] added the very strong horizontal processes on the under side
of the lower jaw in the wombat, and the strikingly large late-
ral portions of this bone in the Brazilian monkeys (cercopithe-
cus seniculus and Belzebub
) between which the bony cavity of
the larynx is situated, which enables them to emit a peculiar
deafening sound.

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.

As the motions of the lower jaw must be materially influenced by
the form of its condyle, and by the manner in which that process is
connected to the articular cavity of the temporal bone; we shall find,
as might have been expected, a close relation between these circum-
stances and the kind of food by which an animal is nourished. Thus
the lower jaw of the carnivora can only move upwards and down-
wards, and is completely incapable of that horizontal motion which
constitutes genuine mastication. Hence these animals cut and tear
their food in a rude and coarse manner, and swallow it in large por-
tions, which are afterwards reduced by the solvent properties of the
gastric juice. Such mammalia, on the contrary, as live on vegeta-
bles, 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 grind-
ing effect, 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.

§ 24. The jaws of mammalia contain teeth* with a very few
[Seite 27] exceptions: the proper whales, (balaenae) the manis, (scaly
lizard
) and the American ant-eaters, are the only genera en-
tirely 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 characterized by its peculiar hardness (sparks
of fire may be produced 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 walrus, the narwhale, (monodon, sea-unicorn) and in
the incisors of the African hog (sus Aethiopicus). Yet these
are all surrounded by an external thin coat of a different sub-
stance 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 substance. 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 phenomenon, resulting from
balls, with which the animal has been shot when young, being
found on sawing through the tooth, imbedded in its substance
in a peculiar manner. Haller employed this fact, both to re-
fute Duhamel’s opinion of the formation of bones by the pe-
riosteum, like that of wood by the bark of a tree; as well as to
prove the constant renovation 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 dissertation. Instances of the fact above-
mentioned, in all which the balls were of iron, may be seen
in several writers.* 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
[Seite 28] tusk 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 pe-
culiar covering. The bony matter has been poured out on the
side of the cavity in a stalactitic form.

The organization of the molar teeth of the Cape ant-eaters
is perfectly anomalous; they consist of vertical tubes. 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 ante-
rior surface, and the molar teeth of several bisulca, as well as
of the elephant, are covered by a very hard black substance
of a vitreous appearance. This black vitreous matter is some-
times covered with a crust of a metallic shining bronze colour;
particularly in the domesticated horned cattle, and sheep.*

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 ex-
ceptions, however, must be made to this general rule. Some mam-
malia, which have teeth for the office of mastication, have others,
which can be only considered as weapons of offence and defence, as
the tusks in 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 animal, but enable it to seize
and hold its prey, and assist in the rude laceration which the food un-
dergoes previous to deglutition. The seal, the porpoise, and other
cetacea, as the cachalot (physeter macrocephalus) 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.

Animals of the genus balaena (the proper whales) have, instead of
teeth, the peculiar substance called whalebone, covering the palatine
surface of the upper jaw: this resembles in its composition, hair,
horn, and such substances.

The lower surface of the upper jaw forms two inclined planes,
which may be compared to the roof of a house reversed; but the two
surfaces are concave. 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
[Seite 29] two or three hundred on each of the surfaces. They are connected to
the bone by the intervention of a white ligamentous substance, from
which they grow; 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 structure proba-
bly 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 likewise two horny processes on the back of the tongue:
these point forwards, and are supposed by Sir Everard Home to pre-
vent the food from passing into the fauces, before it has been suffi-
ciently masticated. In the hystrix, there are six transverse rows of
pointed horny processes at the back of the palate; and about twenty
similar horny teeth on the corresponding part of the tongue.

See Sir Everard Home in the Philos. Trans. 1800, part 2; 1802
parts 1 and 2.

The substance composing the tusks of the elephant, commonly
called ivory, is certainly different from the bone of other teeth. It is,
generally speaking, more hard and compact in its texture; it is dis-
tinguished from all others by the curved lines which pass in different
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 hippopotamus is
harder and whiter; and consequently preferred for the formation of
artificial teeth. In the walrus, the interior of the tooth is composed
of small round portions, placed irregularly in a substance of different
appearance, like the pebbles in the pudding stone; and the molar
teeth have a similar structure.

The curious facts which Blumenbach has mentioned in this section
have been sometimes brought forward to prove the vascularity of the
teeth; a doctrine which is refuted by every circumstance in the for-
mation, structure, and diseases of these organs. It may be first ob-
served, that the appearances 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 substance of the body, the surrounding lace-
rated and contused parts do not grow to the metal, and become firmly
attached to its surface, but they inflame and suppurate in order to
get rid of the offending matter. If the ivory be vascular and sensi-
ble, 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 imbedded in the ivory without any open-
ing for its admission being perceptible. It will be hereafter shewn
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
[Seite 30] 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 the cavity, and lodge in the slightest way on the opposite
side, it will become covered towards the cavity by the newly depo-
sited 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 sur-
rounded 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; and 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 ele-
phant’s tooth. The long axis of the foreign body corresponded to
that of the cavity. No opening for its admission could be discovered,
and it is very clear that no human strength could drive such a body
through the side of a tusk. Philos. Trans. 1801, part i.

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

The front teeth are the incisores of Linnaeus. The corner teeth
are the canini, laniarii, of Linnaeus; cuspidati of Hunter. The back
teeth are the molares. The term of tusks is applied to such teeth as
extend out of the cavity of the mouth.

§ 26. The front teeth in the upper jaw of quadrupeds and
dolphins are those which are implanted in the intermaxillary
bone; the front teeth in the lower jaw are 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 chisel, particularly in the lower jaw, whence
Grew called them dentes scalprarii. In some animals, as in
the beaver and the porcupine, the lower ones have remark-
ably long roots: in many, as in the marmot, the upper ones
also have long roots. In the hare there are two very small
[Seite 31] teeth placed just behind 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, 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 mam-
malia have a more or less oblique position; while in man they
are perpendicular. The orang-outang of Borneo is the only
animal which in this respect at all approaches to the human
subject.

The structure of the incisor teeth, in the rodentia, deserves atten-
tion on several accounts. They are covered by enamel only on their
anterior or convex surface, and the same circumstance holds good
with respect to 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 substances; for which their above-mentioned
sharp edge renders them particularly well adapted. Hence Cuvier
has arranged these animals in a 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 consumed, if they did not possess a power
of growth, by which this loss is recompensed.

These teeth, which are very deeply imbedded in the jaw, are hol-
low internally, 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 ad-
vances to supply the part worn down. The covering of enamel
extends over that part of the tooth which is contained 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 maxillary 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 likewise
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.

[Seite 32]

The constant growth of these teeth, therefore, proceeds in the same
manner, and is effected on the same principles as the original forma-
tion of any 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
contained in a canal of the bone, which descends under 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 intermaxillary
bone, and terminates over the first grinder.

The observations which have been made respecting 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 vascular pulp, which makes
constant additions of successive 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 pro-
bably all other teeth of this description, grow in the same manner.
Further 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 worn away by 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 further asserts that this structure
is found in the grinders of the beaver, p. 99, tab. 9, fig. 4.

In the delphinus Gangeticus, of which there is a specimen in the
Hunterian collection, presented by Sir J. Banks, the change that
takes place in the form of the tooth, as it wears away from long use,
is more remarkable than in most other teeth; for the perfect tooth
has a tolerably sharp enamelled point, while the half-worn one has
a curved, blunted, cutting edge. See Sir Ev. Home’s description of
the teeth of the delphinus Gangeticus, Phil. Trans. 1818, part 1,
p. 417.

[Seite 33]

§ 27. The corner teeth (canini) of the upper jaw lie close
to the intermaxillary bone; hence the remarkable spiral tusk
of the narwhale,* 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 tusks of the babiroussa,
which are very long, and curved 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 considered. The small canine
teeth, which are situated just behind the larger ones, in all the
species of the deer and bear kind, are also remarkable. This
is the case in the brown bear of the Alps, of which I have
three crania; in a black American; in one whose country
is unknown, belonging to the national Museum at Paris; and
in 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 an ante-diluvian bear,
(ursus spelaeus) towards the illustration of whose osteology I
have a large collection, from the four most celebrated caverns
in Germany, viz. that of Scharzfelder in the Harz, of Gailen-
reuter in the Fichtelberg, of Altensteiner in Thuringerwald,
and of Sunwicher in Iserlohn.

The narwhale is found so constantly with only one tusk, that it has
been called 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
which is wanting must have been lost by some accidental circum-
stance, 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 eighteen feet or more; yet they are always slender.

The result of Sir E. Home’s examination of two specimens of the
male narwhale in the Hunterian collection, and of a female sent to
him by Mr. Scoresby, was, that the left tusk of this animal appears
[Seite 34] commonly long before the right one, and that the tusks in the female
come much later than in the male, which facts explain the error of
Linnaeus, and that of the captains of the Greenland ships, who sup-
posed that the females had no tusks.

§ 28. 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 ant-eater. The narwhale 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 and in
man the two front ones* are smaller in the crown, and more
simple in the fang than the posterior: whence J. Hunter calls
them bicuspides, and restricts the name of molares to the
latter.

The molar teeth of ferae and of man have the crown entirely
covered with enamel: this is the case also in the monstrous
fossile animal incognitum of the Ohio, (mammut Ohioticum)
which has been called the carnivorous elephant. In several
glires, (in some, as the marmot, the whole crown is covered
with enamel) in the solidungula, pecora,§ and most balaenae,
bony substance may be seen at the extremity of the tooth,
[Seite 35] intermixed in a tortuous line with vertical productions of ena-
mel.* In many animals which feed on grass, and do not
ruminate, as the solidungula and the elephant, the broad crowns
of the grinding teeth lie chiefly in a horizontal direction
towards each other. In most pecora, on the contrary, their
surface, which forms a zig-zag line, is oblique; the outer mar-
gin 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
consequence of the firm hinge-like articulation of the cylin-
drical condyle.

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 incognitum, or
mammoth, have a similar distribution of this substance.

The grinders of graminivorous quadrupeds, and the incisors also
of the horse, have processes of enamel descending into the substance
of the tooth. These organs have also in the last-mentioned animals
a third component part, differing in appearance from both the others,
but resembling the bone more than the enamel. Blake has distin-
guished 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
their molar teeth is by no means calculated for grinding; and, as the
articulation of the jaw admits no lateral motion, these teeth, 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 attri-
tion 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 attri-
tion longer, and presents the appearance of prominent ridges on the
[Seite 36] worn surface, by which the grinding of the food is much facilitated.

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 polishing 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 distinguished.

The pulp of a grinding tooth of a graminivorous quadruped is di-
vided 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 human sub-
ject, but it is here divided into as many separate shells as there are
processes of the pulp; all of them, however, enclosed 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 de-
scend from the capsule in a contrary direction; and deposit, on the
surface of the shells, enamel distinguishable by its crystalline ap-
pearance, 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 them.
The outer surface of the bone of the tooth is covered by enamel,
which may be compared 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 inequa-
lities 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 grinding tooth of the
horse or cow, the exterior surface will be found to consist of an irre-
gular layer of crusta petrosa: this is succeeded by a waving line of
enamel, within which is the proper bone of the tooth. But the sub-
stance 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 productions of
enamel, is sometimes not completely deposited before the tooth cuts
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 happens to any considerable
extent in the grinders of the horse. In the cow and sheep these cavi-
ties are constantly filled with the dark adventitious 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 forma-
tion 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
[Seite 37] to form internal productions of the enamel. This substance is how-
ever 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 pe-
trosa
fills up the irregularities of this waving line of enamel. A ho-
rizontal section of such a tooth presents the three substances ar-
ranged within each 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 disap-
pear at last from the constant wear of the part in mastication; and
this is improperly called the filling up of the teeth. Hence a crite-
rion arises of the horse’s age.

The grinding teeth of the elephant contain the most complete in-
termixture 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
commencing at their loose extremities, and extending towards 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 invest them with crusta petrosa;
which latter substance unites and consolidates the different portions.
The bony shells vary in number from four to twenty-three, accord-
ing to the size of the tooth, and the age of the animal: they have
been described under the term of denticuli, and have been repre-
sented as separate teeth in the first instance. It must, however, be
remembered, that they are formed on processes of one single pulp.

When the crusta petrosa is completely deposited, the different den-
ticuli 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 the ele-
phant, the front portion of the tooth has cut the gum, and is em-
ployed 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 ante-
rior part has been worn down even to the fang.

A horizontal section of the elephant’s tooth presents 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 pro-
[Seite 38] cesses of bone, upon the different denticuli, running up from the
fangs; a vertical layer of enamel is placed before, and another be-
hind each of these. If the tooth is not yet worn by mastication the
two layers of enamel are continuous at the part where the bone ter-
minates in a point; and the front layer of one denticulus is continu-
ous with the back layer of the succeeding one, at the root of the
tooth; so that the enamel, ascending on the anterior, and descend-
ing on the posterior surface 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 mastication, the pro-
cesses of enamel, which are capable of making a resistance 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 appearance in the Asiatic and African ele-
phants. 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 essential 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 hippo-
potamus,
where there are internal productions of enamel: but Mr.
Macartney has found it in small quantity on the exterior surface of
the tooth near its root.*

§ 29. Certain classes of the teeth are entirely wanting in
some orders, classes, and genera of quadrupeds; 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
[Seite 39] canine and molar, are separated by considerable intervals;
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.

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 con-
tinued and unbroken series.

In the simiae, carnivora, and all such as have canine longer than
the other teeth, there is at least 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)
in which 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 speak-
ing, 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, without 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 macrocephalus) 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 narwhale 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 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 external surface. They are hollow internally, and probably
have a constant growth like the elephant’s tusks. See § 27.

§ 30. The want of satisfactory observations* prevents us
from saying much on the change of the teeth, particularly in
[Seite 40] wild animals. Among the digitata many of the glires, as
the marmot and rabbit, do not appear to change their teeth.*
Some erroneous opinions of former times, as, for instance, that
the domesticated pig changes its teeth, and that the wild ani-
mal does not, hardly require an express contradiction in the
present day. During the time of change in the ferae, parti-
cularly 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 deciduous teeth; but
there are, instead of these, two proper molares on either side
of the jaw. The change of the teeth takes place in the
elephant in a very remarkable manner.§ The new permanent
tooth comes out behind the milk tooth, the vertical layers of
which are gradually removed,ǁ as the formation of the latter
advances. There is, however, perhaps no animal of this
class, in which the first appearance and subsequent removal
of the deciduous teeth takes place at so late a period of life as
in man.

The permanent teeth are generally formed in cavities near the
roots of the temporary ones, and they succeed to the vacancies left
by the discharge of the latter.

A different mode of succession obtains, however, in some instances.
The adult molares of the human subject are not formed near any of
the temporary teeth, but in the back of the two jaws; from which
situation they advance successively towards 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
[Seite 41] 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-
terior tooth coming forwards to supply its place. As this goes
through the same stages as the preceding 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 process 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 transverse 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 mani-
fest 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 embedded 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 successively 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, has been ascer-
tained by Sir Everard Home, in the teeth of the sus Aethiopicus.

Observations on the Structure of the Teeth of Graminivorous Quadru-
peds; 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 (mammoth).

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

§ 31. The crown of the tooth is gradually worn down by
the act of mastication, and receives from this cause a kind of
[Seite 42] polished surface, which is especially observable in the canine
teeth of the pig and hippopotamus. The age of the horse is
determined by the appearance of the front teeth. It has been
observed in the glires, that 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.*

§ 32. 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.

§ 33. It is remarkable, that the animals of this class, at
least the four-footed ones, constantly agree in the number of
their cervical vertebrae. The giraffe or the horse have nei-
ther more nor fewer than the mole or ant-eater. In all there
are always seven, as in the human subject. An unexpected
irregularity has been discovered by Cuvier 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 distin-
guished in the ferae by its immense strength, and by the vast
size of its transverse processes.

The number 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 porpoise; and the six
last in the genus physeter. Léçons d’Anat. comp. tom. i. 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 been recorded, in which more than seven cervical ver-
tebrae have been found in the human subject, although the number
[Seite 43] of those in the back and loins sometimes deviates from the natural
standard.

The transverse processes of the vertebrae, which are particularly
conspicuous in such carnivorous animals as have great strength in
their neck, afford attachment to the large and powerful muscles by
which the animal executes those strong and rapid motions of the
head, which are necessary in attacking its prey, or defending 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 processes are either very short, or altogether deficient in the
long-necked animals, as the horse, camel, giraffe, &c. They would
otherwise afford an obstacle to the bending of the neck backwards.

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

§ 34. The number of dorsal vertebrae is determined 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 (ligamentum nuchae).

§ 35. 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 vertebrae
turned forwards; in the ape, they are in their ordinary posi-
tion, turned upwards.* The transverse processes are remark-
ably large in many ruminantia, as also in the hare.

§ 36. The form and proportions of the sacrum are still
more various. The number of its vertebrae, as they are called,
varies in the different species of the same genus. Thus, in
the common bat it consists of four pieces; in most of the
[Seite 44] simiae it consists of three pieces; in the orang-outang of four;*
in the chimpansé of five. This bone is distinguished in the
horse by large lateral processes at its anterior extremity; and
in the mole by a thin sharp-edged plate, formed by the union
of its spinous processes. A somewhat similar structure is
found in the armadillo, in which animal the whole pelvis has
a very anomalous formation. As the cetacea have no pelvis,
they cannot be said to possess a sacrum.

Most of the simiae, and even some which very much resemble the
human subject, as the orang-outang, which Camper dissected, (simia
pygmaeus
) have the sacrum formed of three pieces, which consequently
leave only two pairs of openings 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; although Silvius and
Eustachius have endeavoured to invalidate this conclusion. See
Vesal. Epist. de Rad. Chynae; also his great work, De Corp. Hum.
Fabrica,
p. 99.

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

§ 37. 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 cercopithecus paniscus, 32; in the two-toed
ant-eater,
41. When an opossum or monkey loses a portion
of the tail, (an accident which has often led to confusion in
determining the species) a peculiar knotty excrescence, some-
times of a carious appearance, takes place at the truncated
extremity.

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 continuation of the vertebral canal, and by openings for the
transmission of nerves. This structure is ascribed by Galen to the
[Seite 45] 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 composed of five pieces,
not perforated. Tyson’s Anat. of a Pigmy, p. 69.

Those vertebrae of the tail of mammalia, which are nearest to the
sacrum, are perforated by a continuation of the canal for the medulla
spinalis. The lower ones are solid. The want of a pelvis renders it
impossible for us to decide the number of sacral and coccygeal verte-
brae in the cetacea; but the whole number of pieces in the spine of
the dolphin and porpoise is 66.

§ 38. The ossa innominata, together with the sacrum, con-
stitute the pelvis.* There is ground for affirming, although
the assertion may appear paradoxical, 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 to the hu-
man subject. Those apes, which most nearly resemble man,
have the ossa innominata much elongated; and in the ele-
phant, 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 syn-
chondrosis, but consolidated into one piece by a bony union.
They are, on the contrary, 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 kangaroo, and other mar-
supial
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) some-
what diverging from each other, and running towards the ab-
domen. They have an elongated and flattened form, and be-
[Seite 46] long exclusively to these animals. But in the Philos. Trans.
of 1802, it is stated by sir E. Home, that the ornithorhynchus
has something of this kind. They support the abdominal
pouch in the female, but are also found in the male; at least
in some species. 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 pubis.*

§ 39. The thorax in most, if not all animals, the marmot
perhaps excepted, of the class mammalia, is narrower, and
deeper from the spine to the sternum, than in man. The less
marked flexure of the ribs of animals, 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-like form of the chest (thorax carinatus) in the most strik-
ing degree.

§ 40. In a very few mammalia, as some bats and armadil-
los,
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 ornithorhynchus, 17; the ele-
phant,
20; 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.

The ornithorhynchus paradoxus and histrix have ribs of a very sin-
gular 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. Meckel de ornithorhyncho paradoxo, 1826.

§ 41. The sternum in most of the mammalia is cylindrical,
[Seite 47] and jointed. This structure occurs even in the quadrumana
and the bears, whose skeletons, in other respects, resemble the
human. The form of this bone is the most singular in the
mole;* where its anterior extremity is prolonged into a pro-
cess, almost resembling a ploughshare, lying under the cervi-
cal vertebrae, and parallel with them.

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 un-
der ground.

§ 42. We proceed to speak of the extremities, as they are
called, which, although they vary considerably in the class of
mammalia, may, on the whole, be compared to those of man in
their chief component parts, and in the mode in which these
are connected together.

Some passages of Aristotle 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, particu-
larly 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 extremities in these animals have
been compared to such parts in the human body as do not in
reality correspond with them.

We may assert, as a general observation, that the four component
parts of the upper extremity, viz. the shoulder, arm, fore-arm, and
hand, can be clearly shown to exist in the anterior extremities of all
mammalia; however dissimilar they may appear to each other on a
superficial inspection, and however widely they may seem to deviate
from the human structure.

[Seite 48]

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 num-
ber 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 phalanges of the fingers elongated. The dolphin, porpoise,
and other cetacea, seem to possess fins, consisting of a single piece.
But we find, under the integuments 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, humerus, bones of the fore-arm, and a hand con-
sisting of five fingers; the same parts, in short, which form the ante-
rior extremity of other mammalia. See Tyson’s Anatomy of a Por-
poise,
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 con-
necting link between the anterior extremities of other mammalia,
and the pectoral fins of the whale kind. The bones are so covered
and connected by integuments, as to constitute a part, adapted for the
purposes of swimming; but they are much more developed than in
the latter animals, and have free motion on each other.

The cold-blooded quadrupeds bear great analogy in the four com-
ponent parts, and in the general structure of their anterior extremi-
ties, 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 considerable and unexpect-
ed resemblance to those of the fore-feet of the mammalia; and the
fin-like anterior member of the penguin contains, within the integu-
ments, the same bones as the wings of other birds.

§ 43. The clavicle has been said, even by some 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 mammalia* besides
these; particularly in such quadrupeds as make much use of
their fore-feet, 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 hedgehog; or for climbing, as the sloth.
Many other animals have, in its place, an analogous small bone,
[Seite 49] merely connected to the muscles,* and called by Vicq d’Azyr
os claviculare to distinguish it from the more perfect clavicles.
This is the case with most of the ferae, 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 bat. Those of the orang-outang have the great-
est resemblance to the human subject. In the two-toed ant-
eater
their form is that of a rib: their figure is most anomalous
in the mole, where they are nearly 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.

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, whe-
ther for the purpose of climbing, digging, swimming, or flying. It
does not exist, on the contrary, in such as use their fore-feet merely for
the purpose of progression; since these limbs must be brought more
forward on the chest, that they may support that part, by being
placed perpendicularly under it. In the genera, which hold an inter-
mediate rank between these, which do not possess so much power in
the fore-feet as the first division of animals, and are not so limited in
their employment as the second, the clavicular bones, or imperfect cla-
vicles, exist.

§ 44. The scapula exists in all red-blooded animals, which
have anterior extremities, or similar organs of motion: conse-
quently in both classes of warm-blooded animals without ex-
ception. The form of this bone varies much even in mamma-
lia; 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 towards the spine, is the shortest in most of
the proper quadrupeds, particularly the long-legged ones with
narrow chest; in which the scapulae lie on the sides of the
chest. In some, as the elephant, the chiroptera, most of the
[Seite 50] 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 coracoid process
and acromion, the two chief projections of this bone, are strong-
est in such animals as have two long clavicles; which might
have been inferred à priori.

§ 45. The remarkable varieties of the anterior extremities,
properly so called, may be most conveniently considered accord-
ing to the orders and genera of animals of this class. The bat
and the mole present the widest deviations from the ordinary
formation of these parts. The radius 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 fur-
nished with a hook-like nail: the phalanges of the four fingers,
between which the membrane of the wing is expanded, 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, connected
to that part by means of two small round bones, which ena-
bles it to spring from great heights. The form of the os hu-
meri in the mole is altogether unparalleled; it is thin in the
middle, and surprisingly expanded at either extremity. The
shovel-like paw of this animal is provided with a peculiar fal-
ciform bone,
lying at the end of the radius. The phalanges of
the fingers are furnished with numerous processes, and have
moreover sesamoid bones; all which, by increasing the angle
of insertion of the tendons, contributes to facilitate muscular
motion. The animals with divided claws and hoofs have some
peculiarities in the metacarpus and metatarsus. In the pig
[Seite 51] these parts consist of four cylindrical bones. In the seal the
large bones of the anterior extremities are not cylindrical, but
flattened; by which structure they serve better the purpose
of rudders. In the pecora, before birth, there are two lying
close together; but they are afterwards formed into one by
the absorption of the septum.* The horse has a single bone
(gamba, Vegetius; in French, le canon; in English, the can-
non bone,
or shank bone), with a pair of much shorter and im-
moveable 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 third
phalanx, which supports the nail. This last phalanx is very
various in its form, according to corresponding variations in
its horny coverings, which may consist of a flat nail or claw,
or hoof, &c.

The humerus becomes shorter, in proportion as the metacarpus is
elongated; so that in animals 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 genera, which have
great and free use of their anterior extremity, have the power of pro-
nation and supination. 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.

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.

[Seite 52]

Several genera of mammalia possess a hand; but it is much less
complete, and consequently less useful than that of the human sub-
ject, which well deserves the name bestowed on it by Aristotle, of the
organ of all organs. The great superiority of that most perfect in-
strument, 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 tak-
ing 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 de-
scribed by Albums 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 styled 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 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 lemur 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 en-
closed in hoofs, lose all power of prehension.

The simiae in general have nine bones in the carpus. Riolani An-
thropographia
and Osteolog. p. 908. Paris, 1626; but there are only
eight in the orang-outang, according to Tyson. There are five car-
pal 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 fin-
gers 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 opposed surfaces first become thin-
ner, then are perforated by several openings, and at last disappear;
so that the adult animal has a single cannon bone, possessing a com-
mon medullary cavity internally, and marked on the outside with a
slight groove at the place of the original separation. There is there-
fore but one metacarpal bone in the adult for the two toes. The
structure of the metatarsus is the same.

In the horse on the contrary, if we allow the splint bones to belong
[Seite 53] to the metacarpus, there will be three to a single toe. Daubenton con-
siders 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 bone of the little finger, and the inner to that of the
thumb. Stubbs views the cannon as the metacarpal of the middle
and ring fingers; and the inner-splint as that of the fore-finger.
Buffon, Hist. Naturelle, 4to. ed. p. 362, vol. iv. Stubbs’s Anatomy of
the Horse.

The single finger or fore-toe of the horse is composed of the usual
three phalanges; the first, which is articulated to the cannon, is call-
ed the pastern; the 2nd is the coronet; and the 3rd, 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.

In those animals which have five toes, as the carnivora, &c., that
which lies on the radial side of the extremity, and is therefore analo-
gous to the thumb, is parallel with the others; and the animal conse-
quently 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 naturally turn-
ed upwards, and not towards the ground; so that its point is not in-
jured in the motions 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 corres-
ponds 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 join-
ed together in the fin.

§ 46. I have something to say respecting the posterior ex-
tremities. 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 se-
veral 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; conse-
quently there is no impression made on the head of the thigh-
bone, while it is found in others, as tha rhinoceros. The pe-
cora
want the fibula almost universally. The peculiar form of
the astragalus, (talus) in the same order is generally known
[Seite 54] from the use which the ancients* made of the bone in their
celebrated game. In some quadrumana, as the orang-outang,
the two posterior phalanges of their toes are remarkably
curved in their shape; a structure which enables them to hold
the branches of trees more firmly, and is in the same degree
unfavourable to the action of progression in an erect position.
Cetaceous animals have no bones in their tail fins, but they
have a bony compages in their thoracic fins, which completely
resembles the front extremities of the seal. This is also the
case with the manati, whose front extremities were formerly
taken for Sirens’ hands.

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 mis-
takes are commonly committed 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
European and the orang-outang in these respects. (White on the re-
gular Gradation in Man and Animals,
&c.) In some other simiae the
leg and fore-arm exceed the thigh and arm. In other animals, although
there are some varieties, the leg is generally 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 be-
yond 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 ruminating animals, and the
horse, is the same with that of 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.

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.
[Seite 55] a part capable of being opposed to the other toes. Hence these ani-
mals can neither be called biped, nor quadruped, but are really quad-
rumanous or four-handed.
They are not destined to go on either two
or four extremities, but to live in trees, since their four prehensile
members enable them to climb with the greatest facility; so that Cu-
vier has denominated them ‘“les grimpeurs par excellence.”’ (Leçons
d’Anat. comp. vol. i. 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 quadrumuna;
and it answers the same purpose. Here however there is a separate
thumb on the posterior extremity only, whence Cuvier calls them pe-
dimanes.

Man is the only animal, in which the whole surface of the foot
rests on the ground; and this circumstance arises from the erect sta-
ture which belongs exclusively to him. In the quadrumuna, 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
hadger, (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 this animal, approaches
considerably to that of man. The same fact is stated of the bear it-
self, properly so called, in the Description anatomique d’un Caméléon,
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 lest phalanx. Here the elongation
of the metatarsus removes the os calcis to such a distance from the
toe, that it is placed midway between the trunk and hoof.

CHAPTER III.
ON THE SKELETON OF BIRDS.

[Seite 56]

§ 47. The skeleton* of birds has considerable uniformity in
the whole class; and it exhibits, when compared with the va-
riously formed skeletons of mammalia, a very great and unex-
pected similarity to that of the human subject.

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

A peculiarity, which seems to be confined to the cormorants,
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 in its open
mouth. But the same motion is performed by some other
piscivorous birds, who are unprovided with this particular
bone.§

Birds have, without exception, only a single condyle, placed
at the anterior margin of the great occipital foramen.

There is also, in the whole class, a bone of a somewhat
[Seite 57] square figure, (called by the French os carré)* by which the
lower jaw is articulated with the cranium on both sides, in the
neighbourhood of the ear.

The ossa unguis are common to birds with mammalia, but
appear to be more general in the former than in the latter:
they are of considerable size, and must be distinguished from
the superciliary bones which probably belong to the acci-
pitres,
or predacious birds, only.

The cranial bones of birds form, as might be expected, a link
between those of the amphibia and the mammalia. The number
of the separate bones on the sides and the base of the cranium is
greater in birds than in the mammalia. The principal difference be-
tween the head of birds and that of man and other mammalia is, that
the cranial bones of the former are less developed, whereas, on the
contrary, they are more completely separated and fully developed in
the latter. Hence all the bones of the skull in birds unite in one
piece, and lose their individuality. The large bones of the face and
of the beak project forward under the small skull. This enlargement
of the face is effected by several bones, which in man and mamma-
lia only exist on parts of the cranial bones; for instance, the lesser
alae of the sphenoid bones in birds are separated from the skull, and
become facial or beak bones.

The single condyle placed at the anterior margin of the great oc-
cipital foramen, gives the head a great freedom of motion, particu-
larly in the horizontal direction. 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.

The os quadratum has a true articulation both with the lower man-
dible 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 second bone presses against the palate, so as to elevate the upper
jaw.

§ 49. The jaws are wholly destitute of teeth. The supe-
rior maxilla, which is completely immoveable in mammalia,
[Seite 58] has, with a few exceptions, more or less motion in birds.* It
either constitutes a particular bone, distinct from the rest of
the cranium, to which it is articulated, as in the psittaci
(birds of the parrot kind); or it is connected 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
very few instances; as in the rhinoceros bird (at least in that
which I possess in my collection).

Respecting the question which has been recently agitated,
whether in the flamingo the upper jaw only is moveable,
and on the contrary the lower one perfectly immoveable; I
can state that in the skull of this bird which I have now be-
fore me, this is in no way the case.

The bill of birds may be considered, in some degree, as supplying
the place of teeth. 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 substance, covering these bones. Its form and structure are
as intimately connected with the habits and general character of the
animal, as those of the teeth are in the mammalia.

The bill is of extraordinary hardness in birds which tear their prey,
as in eagles, or in those which have to bruise hard fruits, as parrots,
or in those which penetrate the bark of trees, as the woodpecker, nut-
hatch,
&c.

This hardness is gradually diminished in those which take less so-
lid nourishment, or which swallow their food whole; and the bill be-
comes a portion of nearly soft skin in those which require a sense of
feeling in the part to enable them to obtain their food in mud, or
water, as in ducks, woodcocks, snipes, &c.

Many birds, especially birds of prey and the gallinaceous tribe, have
the base of the bill covered with a soft skin called cire, the use of
which is not known.

As the bill of birds is at the same time the organ of prehension
and manducation, it has an important influence on their character
and habits. Caeteris paribus, there is greater strength in a short than
in a long bill, in a thick and solid, than in a thin or flexible one;
[Seite 59] but the general form produces infinite variety in the application of
force.

A bill hooked at the end with sharp edges characterises birds of
prey, whether those which prey on the smaller birds and quadrupeds,
or those which prey on fishes, as the albatross, the petrel, &c. The
former have a shorter beak, and proportionally greater strength. A
tooth-like process on each side adds greatly to the strength of such a
bill; hence the birds which are provided with these processes are
considered more noble and courageous than the birds of prey which
want them. The shrike, which possesses them, scarcely yields in cou-
rage to the common birds of prey, notwithstanding its small size, and
the weakness of its wings and feet. When the hooked bill tapers to-
wards the end, it approximates to the knife-shaped bill, which is pe-
culiar to semi-predacious birds, birds of carrion, crows, pies, &c.
The knife-shaped bill indicates a character similar to that of aquatic
birds, such as the grebe, gull, &c.

Another species of strong sharp-edged bill, of an elongated shape,
but without a hook, serves to cut and break, but not to tear. This
is the form of the bill in birds which live upon animals which make
resistance in the water, as reptiles, fishes, &c. Some of these bills are
quite straight, as in the heron, the stork; some are curved towards
the bottom, as in the tantalus, or towards the top, as in the jabiru.

Some sharp-edged bills have their sides approximating, like the
blade of a knife to its handle, and can only serve to seize small sub-
stances; of this description is the bill of the penguin, the puffin (where
it has the further peculiarity of being as deep as it is long) and the
cut-water, in which another singular circumstance is observed, namely,
that the upper mandible is shorter than the lower, so that the bird can
only seize substances by pushing them before it, as it skims along the
water. Lastly, there are some sharp-edged bills, which are flattened
horizontally; they serve to seize fishes, reptiles, and other large ob-
jects. The boat-bill has a bill of this description, which is also fur-
nished with tooth-like processes. Some fly-catchers and green todies
have a similar structure on a minute scale.

Of the bills, of which the edges are not cutting, some are flattened
horizontally. When they are long and strong, they serve for swal-
lowing prey of large dimensions, but which makes little resistance.
When they are long and weak, as in the spoon-bill, in which the flat-
tened extremity of this part gives the name to the bird, they serve
only to imbibe small objects in the mud or water.

The bills of ducks, which are in some degree flattened, the more
conical ones of geese and swans, and that of the flamingo, of which
the upper mandible crosses the lower, have all transverse laminae
ranged along their edges, which, when the bird has seized any
thing in the water, give passage to the superfluous fluid. Thus all
these birds are aquatic. In the goosanders, which in other respects
partake very much of the nature of ducks, these laminae become
small, conical, tooth-like processes, which are well adapted for hold-
ing fish, of which the goosanders destroy great numbers. Wholly
[Seite 60] different from these are the long, thin, soft bills, peculiar to birds
which derive their food from animals in mud or stagnant waters.
They are straight in the snipe, hooked towards the end in the curlew,
and towards the top in the avocette.

The bills of the toucan and the calao are remarkable for their
extraordinary size, which is sometimes equal to that of the whole
bird. The osseous substance of these bills is of an extremely light
cellular texture, without which they would be incapable of maintain-
ing an equilibrium in their flight. The horn which covers them is
so fine as to become irregularly indented on its edges, by the use
which the bird makes of it. In addition to their enormous bills, the
calaos have prominences upon them of the same substance, and of
various forms, the use of which is not known. The calao rhinoceros
is the most remarkable in this respect, as it appears to have two
enormous bills, one over the other.

The wood-peckers have a long, strong, prismatic bill, compressed
at the end, which enables them to penetrate the bark of trees. That
of the king-fisher is nearly similar; but being much longer in pro-
portion to the size of the bird, it cannot serve the same purposes;
besides, the tongue, which is of great importance in determining the
use of the bill, is altogether different.

The short, conical, arched bill of the gallinae serves only to take up
grain and similar substances, which they swallow so quickly that
small pebbles are frequently united with their food. These birds, in
an unconfined state, feed on insects as well as grain; indeed the
young ones, in many species, live for some time exclusively on insects.

The bills of the smaller birds (passeres) present all the varieties of
the conical form, from the broad-based cone of the hawfinch to the
thread-like cone of the humming-bird. Such of them as have a
short strong bill live on grain; those with a long, thin bill, on
insects. Where this weak bill is short, flat, opening very ante-
riorly, as in martins and swallows, the bird seizes flies and butterflies
in the air; if it be long and curved, possessing some strength, as in
the hoopoe, it grubs up worms for its food. The tubulated tongue
of the humming-bird is capable of being elongated so as to enable it
to suck up honey from the calices of flowers.

Of all bills the most extraordinary is certainly that of the cross-bill,
in which the two mandibles cross each other at a considerable angle,
for this formation seems to be directly opposed to the natural pur-
poses of a bill. The bird, however, contrives to pick out the seeds
from the cones of the fir, and it is limited to that species of nourish-
ment.

§ 50. 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 rhi-
noceros bird.
A most remarkable sexual difference appears
[Seite 61] in the skull of the crested hens: 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
impulse, which is propagated to the offspring, is quite unpa-
ralleled in the whole animal kingdom.* I have lately examined
several heads of such hens in a fresh state, 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 cerebellum, as in the common
hen, by an intermediate contracted portion.

§ 51. One of the peculiar characteristic differences of the
cranium of birds when compared to each other, consists in
the mode of separation of the orbits, which are of great size
n the whole class. In some they are separated by a mem
branous 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 diffe-
rent 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 por-
tions of bone, placed far apart from each other, and converging
towards the point of the bill.

§ 52. The want of motion in the back of birds, (their dorsal
vertebrae 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 quote
a few instances, the raven has 12, the cock 13, the ostrich 18,
the stork 19, and the swan 23.

§ 53. The trunk of birds has fewer cartilaginous 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. In the
gallus ecaudatus, in which the rump has been lost by de-
generation, there is nothing more to be seen of the coccyx
than an unshapely knotty process.

[Seite 62]

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 generally in proportion to that of
the legs; but in aquatic birds in a much greater proportion, since
they have to seek their food below the surface of the water on which
they swim.

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 dou-
ble bend, which makes it resemble the letter S. It is by rendering
the two curvatures more convex, or more straight, that the neck is
shortened or elongated. 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 prehensile faculty of the superior extremity.
The atlas has the form of a small ring, which articulates with the
head by only one surface. In proportion to the mobility of the neck
of birds is the fixed state of the dorsal vertebrae, which are connected
together by strong ligaments. The greater part of their spinous
processes are consolidated into a single piece, which runs like a ridge
along the whole back. The transverse processes terminate in two
points, one directed anteriorly, the other posteriorly; they meet
those of the two other classes of vertebrae, sometimes anchylosing
with them, as the spinous processes do with each other. This struc-
ture is necessary to give steadiness to the trunk in the violent
motions required by the action of flying. Accordingly birds which
do not fly, as the ostrich and the cassowary, have a moveable spinal
column.

The vertebrae of the tail are most numerous in those birds which
move it with the greatest force, as the magpie and the swallow. They
have inferior as well as superior spinous processes, and the transverse
processes are long. The last is the largest, and has the shape of a
ploughshare, or flattened disk. The cassowary, which has no visible
tail, has this last bone; in the peacock, it has the shape of an oval
plate, situated horizontally.

§ 54. 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 symphisis pubis, they are quite distant
from each other. The ostrich alone forms a remarkable ex-
ception to this rule, inasmuch as its pelvis, like that of most
quadrupeds, is closed below by a complete junction of the
ossa pubis.

The pelvis of birds consists of the same bones as that of man. The
[Seite 63] length and breadth of the pelvis vary in different classes of birds; it
is broadest and most developed posteriorly in the gallinaceous birds,
which seldom fly and generally go erect. The pelvis is small and
short in birds of prey; that of the passeres, pici, and levirostres holds
a middle place between the pelves of the gallinaceous birds and the
birds of prey. In the anseres, (swimming birds) the pelvis is very
much elongated. It is particularly small and laterally compressed in
some of the grallae, so that the ossa innominata and sacrum form a
kind of keel. In the ostrich and cassowary the pelvis is closed ante-
riorly, and resembles that of mammalia.

§ 55. 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 distin-
guished by a peculiar flat process, which is directed upwards
and backwards.

§ 56. The sternum of these animals is prolonged 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 por-
tion of the trachea. The crista is entirely wanting in the
ostrich and cassowary; where the sternum presents a plane
and uniformly arched surface. This peculiarity of structure
is accounted for by observing, that these birds have not the
power of flying. The wings, which are very small, assist in
balancing the body as they run.

§ 57. The wings are connected to the trunk by means of
three remarkable bones.* The clavicles, which are always
strong, constitute straight cylindrical bones. Their anterior
extremities are connected to the sternum by means of a bone
peculiar to birds; viz. the fork-like bone, or, as it is more
commonly termed, the merry thought. (Furcula, or os jugale,
in Latin, la lunette, or fourchette, in French.) The ostrich
[Seite 64] and cassowary have indeed no separate furcula; but on either
side of the front of the chest an elongated flat bone, consist-
ing of a rudiment of the furcula, with the clavicle and scapula
consolidated into one piece.*

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 struthious birds, (ostrich and cassowary) which are incapable 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 casso-
wary
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 at-
tached to the anterior edge of the dorsal end of the clavicles by
ligament; they are directed upwards towards the neck, where they
are fastened to each other by means of a ligament, and have no con-
nexion whatever with the sternum.”’

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

§ 58. The bones of the wing may be compared on the whole
to those of the upper extremity 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 con-
sists of two phalanges, the other only of one. The most
remarkable deviation from this structure, in respect to the
number, as well as the formation and relative proportion of the
bones, is found in the fin-like wings of the penguin. All
the bones are here of a very remarkable flattened form, as if
they had been pressed; there are two supernumerary bones
[Seite 65] at the elbow, and the bone of the thumb is entirely want-
ing.

§ 59. The bony structure of the lower extremities is more
simple in birds than in mammalia. In general it comprehends
only the following 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. On the
metatarsal bone of the domestic cock and other birds of the
gallinaceous tribe, the spur is situated, a process covered with
horn, between which and the genital organs a peculiar sym-
pathy is supposed to exist.* The place of the patella is sup-
plied, in many cases, by a process of the tibia. As birds have
neither a true fibula, nor tarsus, their tibia is immediately ar-
ticulated 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, five. The psittaci have, how-
ever, a peculiar cross-bone belonging to the great toe; at
least I have found it in several skeletons of psittaci in my
collection. That in the psittacus erithacus resembles a short
cylindrical bone; in the psittacus leucocephalus its formation
is rounder.

Birds certainly have a fibula, contrary to the general 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 meta-
tarsus, 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 metatarsus; 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 extension, 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
[Seite 66] the pulley, on the anterior part of the end of the tibia. This emi-
nence 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 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 requires 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 67]

§ 60. The general form of the body, and consequently 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, secondly, 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.

§ 61. The testudines, (turtles and tortoises) whose whole
skeleton,* and indeed whose whole body has a very peculiar
structure, are entirely toothless; they have, however, a kind
of os intermaxillare in the upper jaw. The horny covering of
the jaws, particularly the upper one, has some resemblance to
the horse’s hoof, in the mode of its connexion with the jaw.
The cavity, containing the brain, is extremely small, in com-
parison with the size of the skull; the greatest part of which,
in the turtle, is occupied by the large lateral fossae, holding
the eye and the powerful muscles that move the lower jaw.

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 consti-
tute the twentieth part of that of the whole head.

The chameleon affords another instance of the same structure: its
brain, according to the description of the Parisian dissectors, does
[Seite 68] not seem larger than a pea; and the whole head, which is of consi-
derable 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 Caméléon, &c. or Blasius’s
Collection, tab. 14.

§ 62. 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.

§ 63. The same bones are found in the pelvis of these ani-
mals, as in the mammalia; but the proportion of their relative
size is inverted. For instance, the ossa pubis are so deep and
broad, that they form the largest flat bones in the whole ske-
leton, while the ilia are the smallest.

§ 64. The form and position of the scapula and clavicle are
the most extraordinary. The former 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.

§ 65. Frogs and toads* have no real teeth, though the mar-
gin of the jaws is denticulated. Their spine is short, and
terminates behind in a straight and single bone, which is re-
ceived into the middle of the somewhat fork-like os innomi-
natum.

§ 66. They have no ribs; but the dorsal vertebrae are fur-
nished with broad transverse processes. The scapula, which
is thin and flat, and a pair of bones, corresponding to the
clavicle, are joined to the sternum.

[Seite 69]

§ 67. The bones of the fore-arm and of the leg have a
peculiarity of structure, in these animals, which deserves no-
tice. These bones consist of a single piece, which is solid
in the middle, without any medullary cavity, but divided at
either extremity into two conical portions, having manifest
medullary cavities.*

§ 68. Among the amphibia of the class of lizards, the cro-
codile
may be taken as an example, on account of many
remarkable peculiarities in its structure. In no other animal
are the jaws of such immense size, in comparison with the ex-
tremely small cavity of the cranium. The anterior part of the
upper jaw consists of a large intermaxillary bone, and the
lateral portions of the lower maxilla are formed of several
pieces joined together. The lower jaw is articulated in a pe-
culiar manner in these animals, although the commencement
of this kind of articulation is seen in the jaw of the testudines:
it has an articular cavity, in which a condyle of the upper jaw
is received. 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 alligator, 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, incapable
of motion, which has been adopted even by such anatomists
as Vesalius and Columbus, has perhaps arisen from this pecu-
liar 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 proportionally
[Seite 70] 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 articulation. There is,
however, no motion of the upper jaw-bone only, similar to that
which occurs in most birds, serpents, and fishes.

§ 69. The numerous teeth of crocodiles have this peculiarity
of structure, that in order to facilitate their change, there are
always two, of which one is contained within the other.*

§ 70. 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 en-
siform cartilage to the pubis, apparently for the purpose of
supporting the abdominal viscera. 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 there was a third intermediate portion
between the chief piece of the rib and each appendix. The
abdominal sternum consisted of seven pairs of cartilaginous
arches connected together. The six front pairs were inter-
rupted by open intervals; and the space between the last
pair and the pubis was filled by a broad piece of cartilage.

§ 71. The serpents have an upper jaw, unconnected with
the rest of the skull, and more or less moveable of itself.

§ 72. We find in their teeth the important and clearly de-
fined 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, be-
set 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 in-
ternally, and is situated longitudinally on either side of the
palate.

[Seite 71]

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

§ 73. It appears, in general, that the number of vertebrae in
red-blooded animals, is in an inverse proportion to the size
and strength of their external organs of motion. Serpents,
therefore, which entirely want these organs, have the most
numerous vertebrae; sometimes more than 300.

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 mysteri-
ous organ are connected to each other in a most curious
way.

It may be observed, in confirmation of the remark, with respect
to the relation between the vertebrae and the external organs of mo-
tion, that the number of vertebrae is very great in fishes of an elon-
gated form, viz. in the eel, which has above one hundred. The por-
poise,
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 hinder ex-
tremities, has a very short spine, consisting of still fewer pieces.

With regard to the peculiar organ of the rattle-snake above al-
luded to, Dr. Mead’s supposition is by no means improbable, that it
may serve to bring birds, &c. within their reach, from the effects of
fear its sound produces, in the same manner that the horns of the ce-
rastes
were formerly imagined, and probably not without justice, to
be employed. Major Gardner, a correct and faithful observer, who
had long lived in East Florida, affirms, that the young Indians of
that country were accustomed to imitate the noise of this serpent, for
[Seite 72] the purpose of taking squirrels, &c. Vide Blumenbach’s Manual of
Natural History,
by Gore, p. 142.

§ 74. Of all animals, serpents possess by far the greatest
number 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
neck. 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.*

Serpents, with the exception of the anguis fragilis, (blind-
worm
) are the only red-blooded animals which have no ster-
num.

The occiput is connected to the atlas by a single condyle in the
crocodile and turtle; in the lizard and tortoise there is a slight appear-
ance of division 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 re-
traction of the head in this animal are effected by the flexion and ex-
tension of the vertebrae of the neck.

The lower jaw is articulated with an eminence of the cranium in
the lizards, turtles, frogs, salamanders, 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 ar-
ticulation in the turtle is by means of a ginglymus. In all the ve-
nomous serpents the upper jaw is moveable on the head, as in birds:
these animals require as extensive an opening of the mouth as possi-
ble, since they swallow others whole, which are actually larger than
their own body.

Sir Everard Home was led to the discovery of the aid afforded by the
ribs of the whole tribe of snakes in the progressive motion of those
animals by the following circumstances. A coluber of unusual size,
brought to London to be exhibited, was shewn to sir Joseph Bankes;
the animal was lively, and moved along the carpet briskly; while it
was doing so, sir Joseph thought he saw the ribs move forward in
succession, like the ribs of a caterpillar.

The fact was readily established, and Sir Everard felt the ribs with
his fingers as they were brought forward; when a hand was laid flat
[Seite 73] under the snake, the ends of the ribs were distinctly felt upon the
palm, as the animal passed over it. This was an interesting disco-
very, as it tended to demonstrate a new species of progressive motion,
and one widely different from those already known.

In the draco volans the ribs form the skeleton of the wings, by
means of which the animal flies, the five posterior ribs being bent
backwards and elongated for that purpose, so that in that instance
the progressive motion is performed by the ribs, but those particular
ribs are superadded for this purpose, and make no part of the organs
of respiration, whereas, in the snake, the ribs are so constructed as to
perform their office with respect to the lungs, as well as progressive
motion.

That ribs are not essential to the breathing of all animals, whose
lungs are situated in the same manner as in snakes, is proved by
the syren having no ribs; but as this animal has also gills, and can
breathe in water as well as in air, the lungs are not so constantly em-
ployed, and probably a less perfect supply of air to them may suffice.
In animals in general, the ribs are articulated to the back-bone by
means of a convex surface, which moves upon a slightly concave one
formed upon two of the vertebrae, partly on the one and partly on the
other, so that there is a rib situated between every two vertebrae of
the back; but in the snake tribe, the head of the rib has two slightly
concave surfaces, which move upon a convex protuberance belong-
ing to each vertebrae, so that there is a rib to each of the vertebrae.

One advantage of this peculiarity is, that it prevents the ribs from
interfering with the motion of the vertebrae on one another. The ver-
tebrae are articulated together by ball and socket joints (the ball being
found upon the lower end and the socket on the upper one) and have
therefore much more extensive motion than in other animals. The
muscles, which bring the ribs forward, consist of five sets, one from
the transverse process of each vertebra, to the rib immediately be-
hind it, which rib is attached to the next vertebra. The next set
goes from the rib a little way from the spine, just beyond where the
former terminates; it passes over two ribs, sending a slip to each, and
is inserted into the third; there is a slip also connecting it with the
next muscle in succession. Under this is the third set, which arises
from the posterior side of each rib, passes over two ribs, sending a
lateral slip to the next muscle, and is inserted into the third rib be-
hind it.

The fourth set passes from one rib over the next, and is inserted
into the second rib. The fifth set goes from rib to rib. On the in-
side of the chest there is a strong set of muscles attached to the an-
terior surface of the vertebrae, and passing obliquely forwards over
four ribs to be inserted into the fifth rib, nearly at the middle part
between the two extremities. From this part of each rib a strong flat
muscle comes forward on each side over the viscera, forming the
abdominal muscles, and uniting in a beautiful middle tendon, so that
the lower half of each rib, which is beyond the origin of this muscle,
and which is only laterally connected to it by loose cellular mem-
[Seite 74] brane, is external to the belly of the animal for the purpose of pro-
gressive motion, and that half of each rib next the spine, as far as the
lungs extend, is employed in respiration.

At the termination of each rib is a small cartilage, in shape cor-
responding to the rib, only tapering to the point. Those of the op-
posite ribs have no connexion, and when the ribs are drawn outwards
by the muscles, are separated to some distance, and rest through their
whole length on the inner surface of the abdominal scuta, to which
they are connected by a set of short muscles; they have also a con-
nexion with those of the neighbouring ribs by a set of short straight
muscles.

These observations apply to snakes in general; but they have been
particularly examined in a boa constrictor, three feet nine inches
long, preserved in the Hunterian museum. In all snakes, the ribs are
continued to the anus, while the lungs seldom occupy more than one-
half of the extent of the cavity covered by the ribs. These lower ribs
can only be employed for the purpose of progressive motion, and
therefore correspond in that respect with the ribs in the draco volans
superadded to form the wings.

CHAPTER V.
ON THE SKELETON OF FISHES.

[Seite 75]

§ 75. We should naturally conclude, from observing the great
diversity in the general form of fishes, that the structure of
their skeleton must be equally various.* 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, par-
ticularly those of the thorax and abdomen, articulated with
peculiar bones destined to that purpose. They have in gene-
ral many more bones unconnected with the rest of the skele-
ton, than the animals of the preceding classes.

§ 76. 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.

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

§ 78. Those fishes which possess teeth, differ very much in
the form, number, and position of these organs. Some species
of bream (as the sparus probato-cephalus) have front teeth
almost like those of man:* they are provided with fangs,
which 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 sub-
sequent 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 lost. It will be understood from
this description that the teeth in question cannot have any
fangs.

The saw-fish only (squalus pristis) has teeth implanted 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 tooth.
One of the most surprising formations about the mouth occurs
in a West Indian species of skate (raia flagellum): it is de-
scribed and delineated by Sloane, as the tongue of the ani-
mal. The specimen, which I possess, consists of a flat bone,
about five inches long, two broad, and of the thickness of the
[Seite 77] thumb. It is composed of 15 curved portions, connected to-
gether likewise; and each of these arches is covered above
with 60 small teeth, which lie close together.

Many fishes have simple teeth of a bony substance, covered by ena-
mel,
and probably formed as in the mammalia. These are the most
common, and may be seen in the pike. When the crown has com-
pletely appeared, the root becomes anchylosed 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 succes-
sive 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 connected to the jaw by a softer substance,
which probably 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 anarrichas 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 se-
paration 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 corresponds to the vomer; in the os hy-
oides; in the bones which support the branchiae; and in those which
are placed at the top of the pharynx. The salmon and pike have
them in all these situations.

§ 79. 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 fun-
nel-shaped depression on both surfaces, and concentric 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 ver-
tebrae in most of the spinous fishes; but in some they are
without this connexion, and in the cartilaginous fishes proper
ribs cannot be said to exist.

[Seite 78]

§ 80. 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 to the os inno-
minatum.

I possess a specimen of the singular bone,* relating to this
subject, which for a long time has been considered a very
obscure one. It is thick, of a roundish flat form, and nearly re-
sembling a smooth chestnut in shape 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 different
magnitude, and resembling the point of an arrow. It belongs
most probably to an East Indian chaetodon (probably to the
chaetodon arthriticus of Schneider); the larger piece being the
basis of the back fin, and the smaller constituting the first ra-
dii of that fin.

§ 81. Lastly, many fishes are furnished with merely muscu-
lar bones (ossicula musculorum of Artedi) which are sometimes
bifurcated, are always situated among the muscles, and facili-
tate their motion.

CHAPTER VI.
ON THE OESOPHAGUS AND STOMACH.

[Seite 79]

§ 82. After the comparative view which we have now taken
of the skeleton, as influencing the general form of the red-
blooded animals, we proceed to consider the other parts of the
animal structure, and their functions, according to the natural
order and series of those functions. The particular classes of
animals will be considered in the subdivision of each chapter,
according to the arrangement most usually followed in teach-
ing zoology.

§ 83. The natural functions, as they are called, which in-
clude, in their most extensive sense, the whole process of nu-
trition, very properly take the lead on this occasion. In the
first place, they exist in all classes of animals without excep-
tion, though under various modifications; they are indeed
common to plants and animals: secondly, the peculiar mode
in which they are performed constitutes the most distinguish-
ing character of animals. For they seek their food by volun-
tary motion, and convey it into the stomach through a mouth.
Partial exceptions to this general rule may be drawn, 1st,
from those animals in which no mouth has hitherto been dis-
covered; for instance, some animalcula infusoria, and in a
certain sense some medusae, which, instead of possessing a sim-
ple opening, take in their nourishment through many apertures;
secondly, from those, in which no manifest voluntary motion
has been hitherto observed, as in several real hydatids. Phy-
siologists have gone further, and have declared certain organ-
ized bodies, in which neither of the above-mentioned charac-
ters, neither a mouth nor voluntary motion, could be discover-
ed, to be animals. Such, for example, are the dropsical blad-
ders occasionally found in the abdomen of persons who have
laboured under ascites, (rarely in any animal except mari,)
in vast numbers, and of various sizes, from that of a goose’s
[Seite 80] 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. iii. 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 person
could think of ascribing to them an independent animal exist-
ence. I have now before me similar cysts from a hen, the lar-
gest of which (about the size of a small hen’s egg), like those
of the above-mentioned patient, were quite unattached; the
rest appeared, on the first examination, from their connexion
with the ovarium, to be nothing else but calices, containing
from a morbid cause, lymph instead of yolk.

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 ani-
mals.

mammalia.

§ 84. 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 bur-
rows.*

[Seite 81]

A cheek-pouch exists also in the ornithorhynchus paradoxus. Phil.
Trans. 1800, part 1, tab. 2, fig. 2.

The salivary glands of the mammalia exhibit 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 openings. There is also a
considerable gland in the dog, under the zygoma, and covered by the
masseter. Its duct, equal in size to that of the parotid, or sub-max-
illary glands, opens at the posterior extremity of the alveolar margin
of the upper jaw. The molar glands and their openings are very
conspicuous in the pig. The cow and sheep have an assemblage of
similar glands in the zygomatic fossa: their excretory ducts open be-
hind the last superior molar tooth.

§ 85. The peculiar glandular and moveable bag, (bursa fau-
cium
) which is placed behind the palate, has hitherto been
only observed in the camels of the old world: and it pro-
bably serves to lubricate the throat of these animals in their
abode in the dry sandy desarts which they inhabit.*

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 in the cetacea exhibit a very singular
structure. The larynx is elongated, so as to form a pyramidal pro-
jection, on the apex of which its opening is found. The pro-
jection 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.

[Seite 82]

§ 86. The oesophagus of quadrupeds is distinguished from
that of the human subject by possessing two rows of mus-
cular fibres, which pursue a spiral course and decussate each
other. In those carnivorous animals which swallow voraci-
ously, as the wolf, it is very large; on the contrary, in many
of the larger herbivora, and particularly in such as ruminate,
its coats are proportionally stronger.*

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 susceptible of this process,
except in extremely rare instances.

It seems extraordinary, on the first consideration, that the
ruminating animals, in whom the passage of the food from the
first stomach into the oesophagus is very easy, should not be
excited to vomit without such difficulty.

I possess a hair-ball which was discharged by vomiting from
the stomach of a cow, which laboured under an affection of
the digestive powers. The substance in question was dis-
charged with violence, after the employment of some white
hellebore placed under the integuments of the breast.

§ 87. The form, structure, and functions of the stomach,
are subject to great variety in this class of animals.§ In most
carnivorous quadrupeds,ǁ particularly those of a rapacious na-
ture, 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
[Seite 83] 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
two portions. Its coats, particularly the muscular one, are
very strong in the carnivora. 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.”’

The truly, carnivorous stomach, as well as the human, which in its
structure is closely allied to it, is according to Sir E. Home, capable
of dividing its cavity into two distinct portions by a transverse con-
traction of its coats, in which state the cardiac portion is, in length,
two thirds of the whole, but, in capacity, much greater, and in se-
veral instances, where the opportunity was afforded of examining the
part immediately after death, the stomach has been found in this form
both in the human body and other animals. This appearance corres-
ponds with the permanent form of the stomach of many other animals.
It is not frequently met with, the fibres of the stomach being readily
relaxed very soon after death by the motion of the liquid commonly
retained in its cavity, and the air which is let loose; so that such
contraction is only to be expected where opportunities occur of a
very early inspection of the stomach after death. But this appear-
ance in the stomachs of women has been attributed by Soëmmering
to the effect of the pressure occasioned by the central bone of their
stays.

§ 88. In some herbivora the stomach has an uniform ap-
pearance externally; but it is divided into two portions inter-
nally, either by a remarkable difference in the two halves of
its internal coat,* as in the horse, 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 ap-
[Seite 84] pearance, particularly if the animal has been fed about two
hours before death.

In the animals alluded to in this paragraph the left half of the sto-
mach is covered with cuticle, while the other portion has the usual
villous and secreting surface. The cuticular 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 trans-
mitted to the true digestive organ; and the different states in which
the food is found in the two parts of the cavity justify the supposi-
tion. Hence these stomachs form a connecting link between those
of ruminating animals on one side, and such as have the whole sur-
face villous on the other.

The larvae of the oestrus 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 mem-
brane, and keeping them parallel till it is pierced through, they ex-
pand them in a lateral direction, 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 oestrus haemorrhoidalis, 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 decided 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 get into the stomach, as also for
a most interesting general account of their history and structure, see
Rees’s Cyclopaedia, art. Bots, which was furnished by Mr. Clarke,
and from which the preceding account is borrowed.

§ 89. In some other mammalia, particularly the herbivorous
[Seite 85] ones, this organ consists of two or more portions manifestly
distinct externally, and forming as many stomachs. There
are two of these in the hamster,* three in the kangaroo and
tajaçu, four in the sloths.§

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

§ 90. The most complicated and artificial arrangement, both
with respect to structure and mechanism, is found in the well
known four stomachs of the ruminating animals with divided
hoofs; of this we shall take as examples, the cow and sheep.

The first stomach, or paunch, (rumen, penula, magnus ven-
ter, ingluvies; Fr. le double, l’herbier, la panse
) 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
[Seite 86] appendices at its extremity, and it is slightly separated into
four parts on the inside. Its internal coat is beset with innu-
merable flattened papillae. It is generally in this first stomach,
seldom in the second, that morbid concretions are formed, of
a globular, or elongated, but yet rounded figure. They are
composed of three kinds of substances: 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 accumu-
lated in the stomach. These either retain a hairy appearance
externally, or they are covered with a dark polished substance,
similar to that which accumulates round their molar teeth.
(See § 24.)

The balls of the chamois, (aegagropilae) consisting of vege-
table matters, particularly of the macerated fibres of the aethu-
sa meum,
are found in the animals from which they derive
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; the western
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 nu-
cleus consists of a red-brown, fine but compact spongy sub-
stance, like that of the vegetable balls.

The second stomach, honeycomb bag, bonnet, or king’s-hood,
(reticulum arsineum, ollula; Fr. le bonnet, le reseau) may be
regarded as a globular appendage of the paunch; and is dis-
tinguished 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 ma-
nyplus,
which is a corruption of manyplies (echinus, conclave,
centipellio, omasum; Fr. le feuillet, le pseautier
); it is distin-
guished from the two former, both by its form, which has been
compared to that of a hedge-hog when rolled up, and by its
[Seite 87] internal structure. Its cavity is much contracted by numerous
and broad duplicatures of the internal coat, which lie length-
wise, vary in breadth in a regular alternate order, and amount
to about forty in the sheep, and one hundred in the cow.

The fourth, or the red, (abomasum, faliscus, ventriculus in-
testinalis; Fr. la caillette
) is next in size to the paunch, of an
elongated pyriform shape, with an internal villous coat like
that of the human stomach, with large longitudinal folds.

§ 91. The three first stomachs are connected with each
other, and with a groove-like continuation of the oesophagus,
in a very remarkable way. The latter tube enters just where
the three first stomachs approach each other; it is then con-
tinued 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 together
so as to form a complete canal, which then constitutes a direct
continuation of the oesophagus into the third stomach.

§ 92. 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 oesopha-
gus, and thus returns into the mouth. It is here ruminated,
and again swallowed, when the groove is shut, and the morsel
of food, after this second mastication, is thereby conducted
directly into the third stomach.* 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
stomach.

The process of rumination supposes a power of voluntary
[Seite 88] motion in the oesophagus; and indeed the influence of the
will throughout the whole process is incontestable. It is not
confined to any particular time, since the animal can delay it
according to circumstances, 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 four
men who ruminated their vegetable food: they assured me
that they had a real enjoyment in doing this, which has also
been observed of others: and two of them had the power of
doing or abstaining from it at their pleasure. I have already,
on another occasion, observed that the final purpose of rumi-
nation, as applicable to all the animals in which it takes place,
and the chief utility of this wonderfully complicated function
in the animal economy, are still completely unknown; what
has been already suggested on these points is quite unsatis-
factory.

Fabricius ab Aquapendente has sufficiently refuted the
visionary notion of Aristotle and Galen, namely, that rumination
supplies the place of incisor teeth, the materials of which are
applied, in these animals, to the formation of horns. Perrault
and others supposed that it contributed to the security of
these animals, which are at once voracious and timid, by shew-
ing the necessity of their remaining long employed in chewing
in an open pasture. But the Indian buffalo ruminates, al-
though 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 inaccessible to beasts of prey.

The food of carnivorous animals approaching in its constituent
elements more nearly to those of the animal than that of the herbi-
vorous 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 leading distinction between the stomachs of these
classes. In the latter animals, the oesophagus opens considerably to
the right of the great extremity, so as 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
[Seite 89] shew this structure very well; it is very remarkable in the mus quer-
cinus,
(Cuvier, Léçons d’Anatomie comparée, tom. v. pl. 36, fig. 11).
In the carnivora, the stomach, which is of a cylindrical form, has no
cul de sac; 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
strictly carnivorous, exhibit this structure the most completely. The
seal and the lion also exemplify it. (Cuvier, pl. 36, fig. 7.)

§ 93. There are still two peculiarities in the stomachs of
some mammalia, which must be mentioned here, before we
proceed to consider that of birds.

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 shilling, full of cavi-
ties that secrete mucus. It resembles, on the whole, the
bulbus glandulosus of birds, and assists in the digestion and
animalization of the dry food which this curious animal takes,
consisting chiefly of the bark and chips of trees, &c.

The stomach of the pangolin (manis pentadactyla) is almost
as thick and muscular as that of the gallinaceous fowls, and
contains, like that of granivorous birds, small stones and gra-
vel, which are probably swallowed, for the same purpose, as
in the case of those birds: that is to say, they are not swal-
lowed, as Burt* supposed, to afford nourishment; but in
order to kill and bruise the insects, &c. which form the ordi-
nary food of the animal, and which might otherwise, by means
of their vitality, resist the chemical action of the gastric juice;
as the intestinal worms and water-newts, which have been
swallowed, do in man and other mammalia.

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

Léçons d’Anat. comp. tom. iii. p. 401.

Sir E. Home is of opinion that a glandular structure exists in the
[Seite 90] stomach of the sea-otter near the pylorus; Philos. Trans. 1796, pl. 2;
and Mr. Macartney has discovered an arrangement of glandular bo-
dies in the dormouse, round the oesophagus just before its termination,
similar in situation and appearance to the gastric glands of birds.

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. Sir E. Home, in the Phil. Trans. 1802, p. 2.

The peculiar structure of the stomachs of the kangaroo, camel, and
lama, which is scarcely noticed in the text, deserves a detailed exa-
mination. The stomach of the kangaroo differs in many particulars
from that of any other known animal, and bears a greater resem-
blance to the human coecum and colon than to any stomach. The
oesophagus enters the stomach very near its left extremity, which,
unlike the corresponding part in other animals, is very small and
bifid. From the entrance of the oesophagus the cavity extends to-
wards the right side of the body, then passes upwards, makes a turn
upon itself, crosses over to the left side before the oesophagus, and
again crosses the abdomen towards the right, making a complete
circle round the portion into which the oesophagus enters, and termi-
nates by a contracted orifice at the pylorus.

Its cavity gradually enlarges from the left extremity through its
whole course, till it approaches the pylorus; it then contracts and dilates
again into a rounded cavity with two lateral processes: beyond this
is the pylorus, the orifice of which is very small. On the anterior
and posterior side of the stomach there is a longitudinal band, similar
to those of the human colon, beginning faintly at the left termination,
and extending as far as the enlargement near the pylorus; these
bands being shorter than the coats of the stomach, the latter are
consequently puckered, forming sacculi, as in the human colon.

When the cavity of the stomach is laid open, the cuticular lining
of the oesophagus is found to be continued over the portion imme-
diately below it, and extends to the termination of the smallest pro-
cess at the left extremity, and nearly to the same distance in the
opposite direction; the cuticular covering is very thin, and extremely
smooth.

The lining of the larger process at the left extremity is thick and
glandular, and in the living body probably receives no part of the
food, but is to be considered as a glandular appendage.

On the right of the oesophagus the cuticle does not end by a trans-
verse line, but terminates first upon the middle of the great curva-
ture, where a villous surface begins by a point, and gradually
increases in breadth till it extends all round the cavity; its origin,
therefore, is in the form of an acute angle. The villous surface is
continued over the remaining cavity as far as the longitudinal bands
extend; and that half of it next the pylorus has three rows of clusters
of glands: one row is situated along the great curvature, and con-
sists of fifteen in number; the other two rows are close to the two
[Seite 91] longitudinal bands, and consist only of nine. Besides these there
are two large clusters of an oblong form, situated transversely, where
the longitudinal bands terminate. The internal surface of the rounded
cavity next the pylorus has a different structure, putting on a tesse-
lated appearance, formed by a corrugated state of the membrane.
Immediately beyond the pylorus is a ring of a glandular structure
surrounding the inner surface of the duodenum.

The stomach of the kangaroo, in the peculiarities of its structure,
forms an intermediate link between the stomachs of animals which
occasionally ruminate; those which have a cuticular reservoir; and
those with processes or pouches at their cardiac extremity, the inter-
nal membrane of which is more or less glandular. The kangaroo is
found to ruminate when fed on hard food. This was observed by
Sir Joseph Banks, who had several of these animals in his possession,
and frequently amused himself in observing their habits. It is not,
however, their constant practice, since those kept in Exeter Change
have not been detected in that act. This occasional rumination con-
nects the kangaroo with the ruminant. The stomach having a
portion of its surface covered by cuticle, renders it similar to those
with cuticular reservoirs; and the small process from the cardia
gives it the third distinctive character; indeed it is so small, that it
would appear as if it were placed there for no other purpose.

The kangaroo’s stomach is occasionally divided into a greater
number of portions than any other, since every part of it, like a por-
tion of intestine, can be contracted separately; and when its length
and the thinness of its coats are considered, this action becomes
necessary to propel the food from one extremity to the other.

Such a structure of stomach makes regurgitation of its contents
into the mouth very easily performed. The food in the stomach
goes through several preparatory processes; it is macerated in the
cuticular portions; it has the secretion from the pouch in the cardia
mixed with it, and is occasionally ruminated. Thus prepared, it is
acted on by the secretion of the gastric glands, which probably are
those met with in clusters in the course of the longitudinal bands,
and afterwards converted by the secretions near the pylorus into
chyle. – See Sir E. Home’s Lectures on comparative Anatomy, vol. i.
p. 155, 4to. edit. to which work we are also indebted for the follow-
ing excellent account of the structure of the stomach of the camel.
The structure of this part in the lama, according to the account
which Cuvier has given of it in the examination of a foetus, (Léçons
d’Anat. comparée,
tom. iii. p. 397,) does not differ essentially from
that of the camel.

Opportunities of examining the camel rarely occur in this coun-
try. One of these, however, was met with thirty years ago, and the
late Mr. Hunter availed himself of it, and made several preparations
to illustrate the different parts of its structure, which are now in the
collection at the College of Surgeons. As the stomach was blown
up, and preserved in a dry state, many peculiarities were left unex-
amined, particularly those respecting the power which the animal
[Seite 92] has of carrying a provision of water as a supply when traversing the
deserts.

Sir E. Home was led by many circumstances to be very desirous
of investigating this subject, and in the year 1805, a favourable op-
portunity presented itself; a camel in a dying state having been pur-
chased by the board of curators of the College of Surgeons, with a
view of illustrating the anatomy of that animal.

As Professor of Comparative Anatomy, Sir E. Home was directed
to examine the peculiarities of the stomach, and to make a report on
that subject.

The camel, the subject of the following observations, was a female,
brought from Arabia, twenty-eight years old, and said to have been
twenty years in England, and twelve years in the possession of the
person from whom the Board of Curators purchased it. Its height
was seven feet from the ground to the tip of the anterior hump.

In December, 1805, when it was purchased by the college, it was
so weak, as hardly to be able to stand: it got up with difficulty, and
almost immediately kneeled down again.

By being kept warm, and well fed, it recovered so as to be able to
walk, but was exceedingly infirm on its feet, and moved with a very
slow pace.

It drank regularly every second day six gallons of water, and
occasionally seven and a half, but refused to drink in the intervening
period. It took the water by large mouthfuls, and slowly, till it had
done. The quantity of food it daily consumed, was one peck of
oats, one of chaff, and one-third of a truss of hay.

In the beginning of February, 1806, it began to shed its coat.
Towards the end of March the wind became extremely cold, and the
animal suffered so much from it, that it lost its strength, refused its
food, and drank only a small quantity of water at a time.

In this state it was thought advisable to put an end to so mise-
rable an existence, and it suggested itself to the committee appointed
for the purposes of this investigation, that if this was done soon after
the animal had drunk a quantity of water, the real state of the sto-
mach might be ascertained.

On the second day of April, by giving the animal hay mixed with
a little salt, it was induced to drink, in the course of two hours, three
gallons of water, not having taken any the three preceding days, or
shewn the least disposition to do so.

Three hours after this, its head was fixed to a beam to prevent
the body from falling to the ground after it was dead; and in this
situation it was pithed by Mr. Cline, junior, assisted by Mr. Brodie
and Mr. Clift.

This operation was performed with a narrow, double-edged po-
niard passed in between the skull and first vertebra of the neck; in
this way the medulla oblongata was divided, and the animal imme-
diately deprived of sensibility.

In the common mode of pithing cattle, the medulla spinalis only is
cut through, and the head remains alive, which renders it the most
cruel mode of killing animals that could be devised.

[Seite 93]

The animal was kept suspended, that the viscera might remain in
their natural state, and in two hours the cavities of the chest and
abdomen were laid open.

The first stomach was the only part of the contents of the abdo-
men which appeared in view. The smooth portion of the paunch
was on the left side, and on the right towards the chest was a cellular
structure, in which it was evident to the feeling that there was air;
but no part of the solid food with which the general cavity was dis-
tended. On the lower posterior part, towards the pelvis, there was
another portion made up of cells, larger and more extensive than
that which was anterior. On pressing on this part, a fluctuation of
its contents could be distinctly perceived. A trochar with the canula
was plunged into the most prominent of the cells, and on withdraw-
ing it, there passed through the canula twelve ounces of water of a
yellow colour, but unmixed with any solid matter.

This fact having been ascertained, the first cavity was laid open on
the left side, at a distance from the cellular structure, and the solid
contents were all removed.

While this was doing, some water flowed out of the cells, and some
out of the second cavity, but the greater part was retained.

That in the second cavity was found nearly pure, while the other
was muddy, and of a yellow colour, tinged by the solid contents of
the first cavity.

On examining the cellular structure, no part of the solid food had
entered it, nor was there any in the second cavity; those cavities
having their orifices so constructed as to prevent the solid food from
entering even when empty.

On measuring the capacities of these different reservoirs in the
dead body, they were as follows: The anterior cells of the first ca-
vity were capable of containing one quart of water when poured into
them. The posterior cells three quarts. One of the largest cells
held two ounces and a half, and the cells of the second cavity four
quarts. This, however, must be considered as much short of what
those cavities can contain in the living animal, since there are large
muscles covering the bottom of the cellular structure, to force out
the water, which must have been contracted immediately after death,
and by that means had diminished the cavities.

By this examination it was proved, in the most satisfactory man-
ner, that the camel, when it drinks, conducts the water in a pure
state, into the second cavity; that part of it is retained there, and the
rest runs over into the cellular structure of the first, acquiring a yel-
low colour in its course.

This confirms the account given by M. Buffon, in his examination
of the camel’s stomach, as well as that of travellers, who state that
when the camel dies in the desert, they open the stomach and take
out the water which is contained in it to quench their thirst.

That the second cavity in the camel contained water had been ge-
nerally asserted, but by what means the water was kept separated
from the food, had never been explained, nor had any other part
[Seite 94] been discovered by which the common offices of a second cavity
could be performed. On these grounds Mr. Hunter did not give
credit to the assertion, but considered the second cavity of the camel
to correspond in its use with that of other ruminants, as appears from
his observations on the subject, stated by Dr. Russel in his history of
Aleppo.

The difference of opinion on this subject led Sir Everard to exa-
mine accurately the structure of the stomach of the camel, and of
those ruminants which have horns; so as to determine, if possible,
the peculiar offices belonging to their different cavities.

The camel’s stomach anteriorly forms one large bag, but when laid
open, this is found to be divided into two compartments, on its poste-
rior part by a strong ridge, which passes down from the right side of
the orifice of the oesophagus, in a longitudinal direction. This ridge
forms one side of a groove that leads to the orifice of the second ca-
vity, and is continued on beyond that part, becoming one boundary
to the cellular structure met with in that situation. From this ridge,
eight strong muscular bands go off at right angles, and afterwards
form curved lines, till they are insensibly lost in the coats of the sto-
mach. These are at equal distances from each other, and, being in-
tersected in a regular way by transverse muscular septa, form the
cells.

This cellular structure is in the left compartment of the first ca-
vity, and there is another of a more superficial kind on the right,
placed in exactly the opposite direction, made up of twenty-one
rows of smaller cells, but entirely unconnected with the great ridge.

On the left side of the termination of the oesophagus, a broad mus-
cular band has its origin from the coats of the first cavity, and passes
down in the form of a fold parallel to the great ridge, till it enters the
orifice of the second, where it takes another direction. It is continued
along the upper edge of that cavity, and terminates within the orifice
of a small bag, which may be termed the third cavity.

This band on one side, and a great ridge on the other, form a canal
which leads from the oesophagus down to the cellular structure in the
lower part of the first cavity.

The orifice of the second cavity, when this muscle is not in action,
is nearly shut; it is at right angles to the side of the first. The second
cavity forms a pendulous bag, in which there are twelve rows of cells,
formed by as many strong muscular bands, passing in a transverse
direction, and intersected by weaker muscular bands, so as to form the
orifices of the cells. Above these cells, between them and the muscle
which passes along the upper part of this cavity, is a smooth surface
extending from the orifice of this cavity to the termination in the
third.

From this account it is evident, that the second cavity neither re-
ceives the solid food in the first instance, as in the ruminantia, nor
does the food afterwards pass into the cavity or cellular struc-
ture.

The food first passes into the first compartment of the first cavity,
[Seite 95] and that portion of it which lies in the recess, immediately below the
entrance of the oesophagus, under which the cells are situated, is kept
moist, and is readily returned into the mouth along the groove form-
ed for that purpose, by the action of the strong muscle, which sur-
rounds this part of the stomach, so that the cellular portion of the
first cavity in the camel performs the same office as the second in the
ruminants with horns.

While the camel is drinking, the action of the muscular band opens
the orifice of the second cavity at the same time that it directs the
water into it; and when the cells of that cavity are full, the rest runs
off into the cellular structure of the first cavity immediately below,
and afterwards into the general cavity. It would appear that camels,
when accustomed to go journeys, in which they are kept for an un-
usual number of days without water, acquire the power of dilating
the cells, so as to make them contain a more than ordinary quantity
as a supply for their journey; at least such is the account given by
those who have been in Egypt.

When the cud has been chewed, it has to pass along the upper part
of the second cavity, before it can reach the third. How this is ef-
fected without its falling into the cellular portion, could not, from any
inspection of dried specimens, be ascertained; but when the recent
stomach is accurately examined, the mode in which this is managed
becomes very obvious.

At the time that the cud is to pass from the mouth, the muscular
band contracts with so much force, that it not only opens the orifice
of the second cavity, but acting on the mouth of the third, brings it
forward into the second, by which means the muscular ridges that
separate the rows of cells are brought close together, so as to exclude
these cavities from the canal through which the cud passes.

It is this beautiful and very curious mechanism which forms the
peculiar character of the stomach of the camel, dromedary, and lama,
fitting them to live in the sandy desarts, where the supplies of water
are very precarious.

The first and second cavities of the camel, as well as those of the
ruminantia, are lined with a cuticle.

The third cavity in the camel is so small, that were it not for the
distinctness of its orifices, it might be overlooked. It is nearly sphe-
rical, four inches in diameter, is not like the third of the ruminantia,
lined with a cuticle, nor has it any septa projecting into it. The cu-
ticle, continued from the second cavity, terminates immediately within
the orifice of the third, the surface of which has a faint appearance of
honey-combed structure; but this is so slight as to require a close in-
spection to ascertain it.

This cavity can answer no other purpose in the oeconomy of the
animal, than that of retarding the progress of the food, and making it
pass by small portions into the fourth cavity; so that the process,
whatever it is, which the food undergoes in the third cavity of other
ruminants, would appear to be wanting in the camel, and consequently
not required.

[Seite 96]

The fourth cavity lies to the right of the first, and has for a great
part of its length the appearance of an intestine; it then contracts
partially, and the lower portion has a near resemblance in its shape to
the human stomach. Its whole length is four feet four inches; when
laid open, the internal membrane of the upper portion is thrown into
longitudinal narrow folds, which are continued for about three feet of
its length; these terminate in a welted appearance; the ridges are
as large as in the bullock, but not so prominent nor so serpentine in
their course, and for the last nine inches the membrane has a villous
appearance, as in the human stomach. Close to the pylorus there is a
glandular substance of a conical form, which projects into the cavity,
the blunt end of it resting upon the orifice of the pylorus. This is
similar to what is met with in the bullock, but still more conspi-
cuous.

The fourth cavity of the camel corresponds with that of the bul-
lock
in all the general characters, and resembles it in most particu-
lars. It exceeds it in length; but the plicae are so much smaller,
that the extent of the internal surface must be very nearly the same
in both. It differs from it in having a contraction in a transverse di-
rection, immediately below the termination of the plicated part, which
has led both Daubenton and Cuvier to consider these two portions as
separate cavities.

On a comparative view of the stomach of the bullock and camel, it
appears that in the bullock there are three cavities formed for the pre-
paration of the food, and one for digestion. In the camel, there is one
cavity fitted to answer the purposes of two in the bullock; a second
employed as a reservoir for water, having nothing to do with the
preparation of the food; a third so small and simple in its structure,
that it is not easy to ascertain its particular office. It cannot be
compared to any of the preparatory cavities of the ruminantia, as all
of them have a cuticular lining, which this has not; we must there-
fore consider it as a cavity peculiar to ruminants without horns, and
that the fourth is the cavity in which the process of digestion is car-
ried on.

In the stomachs of ruminating animals, the processes which the
food undergoes before it is converted into chyle, are more complex
than in any others. It is cropped from the ground by the fore-teeth,
then passes into the paunch, where it is mixed with the food in that
cavity; and it is deserving of remark, that a certain portion is always
retained there; for although a bullock is frequently kept without food
several days before it is killed, the paunch is always found more than
half full; and as the motion in that cavity is known to be rotatory,
by the hair balls found there being all spherical or oval, with the hairs
laid in the same direction, the contents must be intimately mixed to-
gether. The food is also acted upon by the secretions belonging to
the first and second cavities; for although they are lined with a cu-
ticle, they have secretions peculiar to them. In the second cavity
these appear to be conveyed through the papillae, which in the deer
are conical; and when examined in a lens, whose focus is half an
[Seite 97] inch, they are found to have three distinct orifices, and that part of
each papilla next the point is semi-transparent. These secretions are
ascertained by Dr. Stevens’s experiments to have a solvent power in a
slight degree, since vegetable substances contained in tubes were dis-
solved in the paunch of a sheep.*

The food thus mixed is returned into the mouth, where it is masti-
cated by the grinding teeth; it is then conveyed into the third ca-
vity, in which a gas is emitted. This was examined by Sir Humphrey
Davy and Mr. William Brande, and was found to be inflammable, and
not to contain carbonic acid, which establishes a difference between
this process and fermentation; the food is then received into the up-
per portion of the fourth cavity.

The changes which are produced on the food in the three first ca-
vities, are only such as are preparatory to digestion; and it is in the
fourth alone that that process is carried on. In the plicated portion
the food is acted on by the secretion of the gastric glands; in that
portion of the fourth cavity of the deer’s stomach, small orifices are
seen in the internal membrane leading to the cavities, which appear
to be the openings of these glands.

In the lower portion the formation of chyle is completed.

birds.

§ 94. As we have spoken above of the cheek-pouches of
some mammalia, we must here take notice of the throat sac,
which is found in the male 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 discovered.

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 reser-
voir for the food, which consists of fishes. By means also of this
bag, the animal feeds its young until they are of sufficient strength
to provide for themselves.

§ 95. The oesophagus, which generally descends on the
right of the trachea, as well as its opening into the stomach,
is of immense size in many carnivorous birds; considerably
larger indeed than the intestinal canal. The capaciousness of
[Seite 98] this tube enables it to hold for a time the entire fish, and
large bones which these birds swallow, and which cannot be
contained in the stomach; and facilitates the discharge, by
vomiting, of the indigestible remains of the food, which form
balls of hair, feathers, and bony matter. A sea-gull, which I
kept alive for some years, could swallow bones of three or four
inches in length, so that the lower end only reached the sto-
mach, and was digested, whilst the rest projected into the
oesophagus, and descended gradually, in proportion as the
former was dissolved.*

Proper salivary glands, such as secrete 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 of these animals, but in their gizzard. Birds, how-
ever, have a very copious apparatus of those mucous follicles, which
form the glandulae labiales, buccales, linguales, &c. of the human sub-
ject. 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 con-
spicuous in the gallinae. The ostrich, in particular, has two flattened
bodies at the upper and back part of the palate, which may be com-
pared in some respects to tonsils. The surface of these is covered
with innumerable foramina, from which a tenacious mucus may be
expressed. The soft palate is entirely deficient in birds: the nostrils
open on the bony palate by longitudinal slits, the sides of which
are guarded by soft pointed papillae.

§ 96. The oesophagus expands just before the sternum into
the crop, (ingluvies, prolobus; Fr. le jabot) which is furnished
with numerous mucous, or salivary glands, disposed in many
cases in regular rows. In such birds as nourish their young
from the crop, the glands swell remarkably at that time, and
secrete a greater quantity of fluid. This takes place in an
inverse ratio to the age of the young pigeon, as long as the
[Seite 99] old birds keep their food in the crop. 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 prey.*

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
appearance from which the name of the bird is derived. 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 constitute 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
wanting in the piscivorous birds; but its place is supplied by the
great size of the oesophagus, in which entire fishes are held until they
can pass into the stomach. The heron, cormorant, &c. are examples
of this peculiarity.

§ 97. There is another glandular and secretory organ, much
more common than the crop, belonging indeed very generally,
though it is wanting in some birds, as the king’s-fisher, to the
whole class; this is the bulbus glandulosus, (echinus, infundi-
bulum, proventriculus, corpus tubulosum
) which is situated
before the entrance of the oesophagus into the proper sto-
mach, 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 sto-
mach. In some other birds, as the psittaci, ardeae, (crane,
stork,
&c.) its appearance is different in form from that of the
proper stomach, and its size is larger; while, on the contrary,
in gallinaceous birds, it is much smaller.

[Seite 100]

The term bulbus glandulosus (ventricule succenturié, Cuvier) is ap-
plied 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 gallinaceous 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 apposition 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 are hollow internally, and open into the cavity of the bul-
bus.
The fluid secreted by them, which, from their number and
size, must be furnished 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 discerned.
The ostrich affords an opportunity of examining them to great advan-
tage. In the African species the oesophagus is dilated into an im-
mense bag, capable of holding several pints of water, and is five or
six times larger than the gizzard itself, which is placed on the right
and anterior part of this dilatation. The glands do not surround the
tube, so that the term zone would be here inapplicable. They
form a long but narrow band, commencing at the termination of the
oesophagus, and running along the front of the bag towards the giz-
zard. This band measures about twelve inches in length, and not
more than three at its greatest breadth. The size of the individual
glands varies: they are largest in the middle, and decrease towards
either margin of the band. Some of them equal a large pea, and
their openings are of a proportional size. They are arranged in close
apposition to each other, and the inner surface of the pouch is covered
by a continuation of the insensible lining of the gizzard, which sepa-
rates very easily from the surface.

The solvent glands in birds are larger, and more distinct from the
other parts of the digestive organs than in the mammalia. The solvent
glands in the whole of the extensive genus falco of Linnaeus are cy-
lindrical bodies, with very small canals, a villous internal surface, and
thick coats, open at one end, closed and rounded off at the other;
they are placed on the outside of the membrane which lines the
cardiac cavity, they lie parallel to one another, and nearly at right
angles to the membrane through which they open, the closed end
being slightly turned upwards, so as to make the orifice the most de-
pending part. In the golden eagle (the falco chrysaëtos, L.) and the
sea eagle, (falco ossifragus) they form altogether a broad compact
belt; but in the hawk (falco nisus) this belt is slightly divided into
four distinct portions; immediately below these glands the cavity
becomes wider, and is inclosed in a digastric muscle of weak power,
with a flat tendon on each side. The internal surface of this cavity,
which is the gizzard, is soft and vascular.

[Seite 101]

In all animals that live on animal food the solvent glands appear
to have a similar structure to that which has been just described,
only differing in size and situation. In the solan goose (pelecanus
bassanus
) these glands are rather larger than in the eagle, but are
placed in the dilated part of the cavity of the gizzard, forming a
complete belt of great breadth, consequently are extremely nu-
merous.

In the heron (ardea cinerea) they are in the same situation as in the
solan goose; they are thinly scattered, and do not form a complete
belt, being more numerous on the anterior and posterior surfaces. A
ball of fish-bones, held together by mucus, was found in the cavity of
the gizzard.

In the cormorant (pelecanus carbo) the situation of the solvent
glands is the same as in the solan goose; but they only form two
circular spots, one anterior, the other posterior.

In all these birds the inner membrane of the gizzard is soft and
smooth, but that portion which covers the solvent glands has a more
spongy or villous appearance; and this part secretes a mucus which
the other parts do not. This fact appears to be ascertained by the
following circumstances: on examining the gizzard of a cormorant
that died in consequence of an inflammation in the oesophagus, which
had been communicated to the internal membrane of the gizzard, a
viscid mucus was found upon the surface covering the solvent glands,
and this was not met with in any other part; so that the mucus had
been evidently secreted there, and was afterwards coagulated by the
liquor of the solvent glands poured upon it, coagulation being the
first process which takes place in the act of digestion. This ex-
plains the circumstance of ascarides being frequently found enve-
loped in mucus in this part of the cormorant’s gizzard, the mucus on
which they feed being secreted in consequence of the irritation they
produce on the membrane. In the same manner the flakes in the bi-
liary ducts of the sheep increase the secretion of the bile by ir-
ritating these canals, and then feed on it.

In birds that live upon fish and sea insects with crustaneous
coverings, as the sea-gull, (larus canus) the gizzard has a horny cu-
ticular lining, and the solvent glands are in the same situation as in
the genus falco.

In those birds that live on land insects, some of whose coverings
are soft, others hard, there is a difference in the structure of the di-
gestive organs from what has been described. The solvent glands
are placed in a triangular form in the cardiac cavity, and immediately
under it is a small gizzard with a horny lining. Of this kind is the
wood-pecker (picus minor).

There is still another variety in the structure of these organs. In
the little auk (the alea alle) the solvent glands are spread over a
greater extent of surface than in any other bird that lives on animal
food, and the form of the digestive organs is peculiar to itself. The
cardiac cavity appears to be a direct continuation of the oesophagus,
distinguished from it by the termination of the cuticular lining, and
[Seite 102] the appearance of the solvent glands. The cavity is continued down
with very gradual enlargement below the liver, and is then bent up
to the right side, and terminates in a gizzard; when the cavity is
laid open, the solvent glands are seen at its upper part, every where
surrounding it, but lower down they lie principally upon the poste-
rior surface, and where it is bent upwards, towards the right side,
they are entirely wanting. The gizzard has a portion of its anterior
and posterior surfaces opposite each other, covered with a horny cu-
ticle.

In birds that live principally on vegetable food, the solvent
glands have a different structure, according to the substances the
birds are intended to feed upon, and vary in situation according to
the habits of life.

In the pigeon (columba domestica) their situation is the same as in
the genus falco, but their size is small, the external orifices large,
and the coats thin, so that they resemble the glands in the English
heron, having however larger cavities.

In the swan (anas cygnus) the solvent glands appear to be cylinders,
as in the genus falco, but are not straight, bending upon one another
in a direction obliquely upwards; their internal surface is not villous,
but rather broken and irregular.

In the goose (anas anser) they have the same situation, but when
laid open, the sides are found to be cellular.

In the common fowl (phasianus gallus) these glands are made up
of four small short processes uniting in a middle tube, which opens
externally by one orifice.

In the turkey (meleagris gallopavo) they consist of four small pro-
cesses, which diverge from each other in opposite directions.

In many large birds that only walk and run, their wings being too
small to enable them to fly, the digestive organs are formed in many
respects differently from those of other birds.

In the cassowary (cassuarius emu) the solvent glands are situated
between the crop and gizzard, as in many other birds, but this part
is dilated into a large cavity, and separated from the gizzard by an
oblique muscular valve; in this cavity the food may be retained for
some time, but cannot be triturated there, since the stones and other
hard bodies swallowed will readily force a passage into the gizzard.

In the American ostrich (rhea Americana) the solvent glands are
fewer in number than in other birds. They only occupy a small
portion of a circular form on the posterior side of the cardiac cavity;
this however is compensated by the complex structure of which they
are composed. To each gland there is one common orifice; when
the cavity to which it leads is laid open, three smaller orifices are ex-
posed, each of which communicates with five or six processes like
the fingers of a glove. The structure is similar to that of the solvent
glands of the beaver among quadrupeds. The cardiac cavity in
which the glands are situated is dilated to a large size, as in the cas-
sowary, and there is a similar muscular valve, separating it from the
gizzard. The digastric muscle is weak, but the fibres of which it is
[Seite 103] composed, and tendons between the two bellies of the muscle, are
beautifully distinct.

In the African ostrich (struthio camelus) the solvent glands are un-
usually numerous; the space in which they are situated is not only
dilated into a cavity, but is continued down below the liver, and
then bent up upon itself towards the right side, where it terminates
in a strong gizzard nearly at the same height as the beginning of the
cardiac cavity. The gizzard is unusually small, the grinding sur-
faces do not admit of being separated to a great distance from one
another; and on one side there are two grooves, and two corres-
ponding ridges on the other. Beyond the cavity of the gizzard is an
oval aperture, with six ridges, covered with cuticle, to prevent any
thing passing out of the gizzard till it is reduced to a small form.
The cardiac cavity of one of these birds was found to contain stones
of various sizes, pieces of iron, and halfpence; but, between the
grinding surfaces of the gizzard, there were only broken glass-beads,
of different colours, and hard gravel mixed with the food. The
cassowary and American ostrich differ from birds that fly, in having
the solvent glands placed in a cavity of unusual size, and the muscu-
lar structure of the gizzard uncommonly weak; their mode of pro-
gression, which is a kind of run, producing so much agitation be-
tween the stones and the food, as to render a strong muscular action
unnecessary.

In the ardea argala, a native of Bengal, which feeds upon carrion,
and is exceedingly voracious, the solvent glands are differently
formed from those of any other bird; each gland is made up of five
or six cells, and these open into one common excretory duct. The
glands are disposed in two circular masses, one on the anterior, the
other on the posterior surface of the cardiac cavity; putting on a si-
milar appearance to those of the cormorant, but differing both in
structure and situation. The gizzard is lined with a horny cuticle,
nearly of the same general appearance as that of the crow, and the
digastric muscle is of similar strength.

In the parrot tribes, which feed principally on seeds and fruits,
there is a different formation of the digestive organs. There is a
crop on the right side, as in the fowl, but the cardiac portion is
unusually large, and the gastric glands are spread over a consider-
able portion of its surface, but are wanting at the lower part, and
immediately below there is a regularly formed gizzard of a very di-
minutive size. In this respect the parrot accords very nearly in its
digestive organs to the wood-peckers among those birds that live
upon animal food, having a cavity in which the soft substances may
be acted upon by the gastric liquor, and also a gizzard, in which any
harder substances may be broken down, and by that means rendered
fit to be acted upon by the secretion of the gastric glands.

In examining the gastric glands of the Java swallow Sir E. Home
thought that he saw an obvious difference between the appearance
of the orifices, by which the secretion is forced into the gizzard of
this bird, and that of the common swallow. But Mr. Clift, who saw
[Seite 104] the preparation to which Sir Everard alludes, has assured the editor
that he could not perceive the difference which Sir Everard mentions.

Sir E. Home concludes, from a comparison of the peculiarities in
the structure of the digestive organs in birds generally, and particu-
larly of the solvent glands, gizzards, and intestines in the cassuarius
emu,
a native of Japan, the rhea Americana, a native of South Ame-
rica, and the struthio camelus of Africa, that the gizzard becomes
more and more fitted to economize the food as the country to which
the bird belongs becomes less fertile, and that the extension of the
lower intestines and coeca warrants us in believing that the processes
carried on in them render the undigested food subservient to the ani-
mal’s support. See Phil. Trans. 1813.

§ 98. In most birds, the stomach lies at the upper* part of
the abdomen, that is, close to the spine, and rests in a manner
on a stratum of intestines; in the cuckoo, however, it lies be-
low. This peculiarity does not belong exclusively to that cu-
rious bird, for I have found it in the ramphastos, and the
corvus caryocatactes (the nut-cracker).

§ 99. 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, mus-
cular globes of the granivorous genera. But there are both
many intermediate links between these extremes, and at the
same time considerable analogies in the structures, which are
apparently the most opposite. This is particularly observable
in the course of the muscular fibres,§ and in the callous struc-
ture and appearance of the internal coat,ǁ in which points many
membranous stomachs have a great resemblance to those of
the gallinae.

§ 100. Both parts, but particularly the muscular, are very
[Seite 105] strong in the gizzard (ventriculus bulbosus) of granivorous
birds.* We find here, instead of a muscular coat, four im-
mensely thick and powerful muscles; viz., a large hemisphe-
rical pair at the sides, (laterales) and two smaller ones (inter-
medii
) at the two ends of the cavity; all the four are distin-
guished, both by the unparalleled firmness of their texture,
and by their peculiar colour, from all the other muscles of the
body.

The internal callous coat must be considered as a true epi-
dermis,
since, like that part, it becomes gradually thicker from
pressure and rubbing. It forms folds and depressions to-
wards 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 and narrow; its
lower orifice is placed very near the upper. Every part of
the organ is, indeed, calculated for producing very powerful
trituration. The numerous experiments which Reaumur 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 sixteen grains of its weight.§ The end and
use of swallowing stones with the food, the well-known in-
stinctive practice of granivorous birds, have been very dif-
ferently explained. Caesalpinus considered it rather as a
medicine than as a common assistance to digestion; Boer-
haave, as an absorbent for the acid of the stomach; Redi,
as a substitute for teeth. According to Whytt, it is a me-
chanical irritation, adapted to the callous and insensible na-
ture of the coats of the stomach. Spallanzani rejected all
[Seite 106] 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 con-
sider 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 paradoxical
opinion has, however, been already refuted by Hunter and
Fordyce.* The use of swallowing these stones seems to me to
consist in this, that they kill the grain, and deprive it of its vi-
tality, which otherwise resists the action of the digestive pow-
ers. Thus it has been found, that if the oats and barley given
to horses, are previously killed by heating, the animal only re-
quires half the quantity, and yet thrives equally.

amphibia.

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

§ 102. 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.

§ 103. 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.

Reptiles resemble birds in having their nostrils terminated by two
longitudinal slits on the palate, and in the want of the velum palati
and epiglottis.

The oesophagus of the serpent kind is of immense magnitude; for
these reptiles swallow animals larger than themselves, which are re-
tained for a considerable time in the tube and descend into the sto-
[Seite 107] mach by degrees, where they are slowly subjected to the action of
the gastric juice. The whole process sometimes occupies many days,
or even weeks.

fishes.

§ 104. The oesophagus is short in most fishes; but this
character is not universal, as Aristotle supposed;* nor is a
long oesophagus peculiar to fishes of an elongated form. The
large stomach of the tetrodon hispidus is particularly worthy
of notice, for the animal can fill it in case of necessity with air,
and change its naturally long form into a spherical one.

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).

§ 105. The size and form of the stomach vary very consi-
derably in this class. Its coats are thin in most fishes, but in
some they are very thick and muscular,§ and have a callous
internal covering; still, however, the resemblance between
these and the stomachs of granivorous birds is very remote.

insects.

§ 106. I have already observed, on another occasion,ǁ that
the business of nutrition in insects does not seem to have for
its object the mere preservation of the individual, as in most
[Seite 108] red-blooded animals; but chiefly the consumption of organ-
ized 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 comparison with the short intestinal canal:
while those, on the contrary, which take little or no nourish-
ment in their perfect state, have this organ remarkably dimi-
nished, and as it were contracted.

§ 107. Our limits will allow us to take but little notice here
of the endless varieties and peculiarities of internal structure,
which occur in the different genera and species of this multi-
form class of animals. We shall therefore only bestow two
words on those of the oesophagus and stomach. In several
cases the commencement and termination of the alimentary
canal, the oesophagus, and rectum, are surrounded by an annu-
lar portion of the spinal marrow.

In the earwig (forficula auricularia) the upper orifice of
the stomach is furnished with two rows of teeth.§

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
[Seite 109] portions,* which have been compared with the stomachs of
the ruminating mammalia.

We have already (§ 1) mentioned the stomach of the lobster,
and some other species of the genus cancer: which is pro-
vided with several portions of bone. It contains also three
teeth, which, together with the stomach itself, are annually re-
produced, at least in the craw-fish (cancer astacus).

The crustacea, and some insects, are furnished with organs of mas-
tication 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, pos-
sess 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 parti-
cularly the lucanus cervus, or stag beetle, and the staphylinus maxillo-
sus,
are examples in which the jaws are very large and manifest, and
often possess denticulated edges. All the genera of the following or-
ders have jaws; viz. the coleoptera, orthoptera, neuroptera, and hyme-
noptera.
The insects of the remaining orders derive their nourish-
ment chiefly from liquids; which they get either from animal or ve-
getable substances by means of a spiral and tubular tongue, or a soft
proboscis, (as in the lepidoptera) with a broad opening, admitting of
extension and retraction, (the hemiptera) or a horny pointed tube,
containing sharp bristly bodies internally (the diptera and aptera).

The stomach of the bee is a transparent membranous 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 therefore collapse when empty. To certain parts of this
bony structure, round the pylorus, the teeth are affixed. Their sub-
stance is extremely hard, and their margin is serrated or denticulated:
as they surround the tube, near the pylorus, nothing can pass that
[Seite 110] opening, without being perfectly comminuted. These bones and teeth
are moved by peculiar muscles.

vermes.

§ 108. We can only select a few instances,* as examples of
this class, which includes a great number of creatures, differ-
ing widely from each other.

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

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

The powerful stomach of the bulla lignaria contains three
hard calcareous shells, by which the animal is enabled to bruise
and masticate the other testacea, on which it feeds.§ This
stomach was lately taken by some naturalists for a peculiar
genus, of an entirely new order of three-shelled testacea.

[Seite 111]

In most of the proper mollusca, the stomach is of a simple
membranous structure, and of very different comparative mag-
nitudes. I have found it very large in the scyllaea pelagicum.
It occupies the greatest part of the body in the leech, and is
divided internally by means of ten imperfect fleshy partitions,
into somewhat separate portions.

Lastly the armed polypes (hydrae) and other similar zoo-
phytes,
can hardly be considered as any thing more than a
mere stomach, having its openings furnished with tentacula.

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 articu-
lated. 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 surround-
ed 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 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 organs 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 sometimes hard parts
forming a kind of jaws or teeth. Thus in the nereis, the mouth pos-
sesses several calcareous 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 semi-circular
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 ar-
rangement; 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 organ of mastication.

The stomach of the vermes is, in general, a membranous 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 stag-
nalis,
and the onchidia have gizzards. The aplysia has three strong
muscular stomachs, 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 lob-
ster’s teeth, when its crustaceous covering falls off.

CHAPTER VII.
ON THE INTESTINAL CANAL.

[Seite 112]

mammalia.

§ 109. The intestinal canal (which is the most common part
in the whole animal kingdom after the stomach), is distin-
guished in this class by two peculiarities, which depend on
the mode of nutrition. It is comparatively shorter in carnivo-
rous 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 intestines; 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.

It is worthy of notice how the calibre of the intestines and
the strength or thickness of their tunic bear no definite pro-
portions to each other. Hence the small intestines of a full
grown seal, which are very long, and of the size of the little
finger in thickness, have much stronger tunics than those of
the opossum, the calibre of which is equal to the size of the
thumb.*

In considering the proportionate lengths of the intestinal canal,
and the relation which these bear to the kind of food on which the
animal subsists, 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 intes-
tine, and vice versa. The structure of the stomach must also be
considered; as, whether it is formed of more than one cavity; whe-
ther the oesophagus and intestine communicate with it in such a
manner as to favour a speedy transmission of the food; or, whether
[Seite 113] there are culs de sac, 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 comminution which the food experiences in
the mouth, must likewise be viewed in connexion 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.

In omnivorous animals, the length of the canal holds a middle
rank between those which feed on flesh, and such as take vegetable
food. Thus, in the rat, its proportion to the body is as eight to one;
in the pig thirteen to one; in man six or seven to one. The diminution
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 concurs 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 three or five to one.

The ruminating animals present the opposite structure. The food
undergoes a double mastication, and passes through the various ca-
vities of a complicated stomach. The intestines are very long; twenty-
seven times the length of the body in the ram. Hence the large intes-
tines are not dilated, or cellular; nor is there a coecum. 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 coecum is of a vast size; equal, indeed, to the stomach. The
rodentia, which live on vegetables, have a very large coecum, and a
canal twelve or sixteen times as long as the body. In the rat,
which can take animal as well as vegetable food, the canal is shorter
than in the other rodentia.

There are some exceptions to the rule which we have just men-
tioned respecting the length of the canal in carnivorous and herbi-
vorous animals. The seal, which takes animal food, has very long
intestines: 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 carnivorous 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 coecum, nor distinction of large intestine.

[Seite 114]

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 of the canal be-
tween 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 to one. They are, on the con-
trary, 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, although 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.

§ 110. The valvulae conniventes of the small intestine are
more faintly marked in most mammalia than in man; in some,
indeed, they do not exist at all, and this happens both in car-
nivorous 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 intes-
tine, 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 ani-
mals only of this class, as, for instance, in the hedgehog,
ornithorhynchus, and racoon.

[Seite 115]

§ 111. There is great variety with respect to the coecum 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 fur-
nished internally with a peculiar spiral valve. The marmot
of the cape, (hyrax capensis
) has first a large coecum, and
then, further on, two other conical blind appendices.*

The appendicula vermiformis is wanting in many mammalia;
even in some of the simiae, as the silvanus, &c.

Most of the animals which have a vertebral column, have the
intestine divided into two parts; viz. the large and small. The lat-
ter 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 mammalia which have this distinction,
the separation is marked by one or more appendages, which have
the name of coecum when large, of vermiform appendix 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 ornithorhynchus hystrix
has an appendix only; and most other mammalia have only a coecum.
All the simiae, except the orang-outang, have a coecum, like that of
man, but want the appendix vermiformis.

Several possess neither coecum nor appendix, as the edentata,
(except the proper ant-eaters); the tardigrada, the bats, the planti-
grada,
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 wanting; as in the sloth and armadillo.
When this distinction does not exist, the large intestine is charac-
terized by the want of villi, by a greater thickness of its coats, and
particularly by a strong layer of longitudinal muscular fibres.

In animals, which have a coecum, this part appears to be merely a
prolongation of the large intestine 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 opossum, most of the rodentia and ruminantia.
In the herbivorous mammalia the coecum is generally large and cel-
lular; 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 complicated, the coecum is of a moderate size, and uniform. It
[Seite 116] is large and cellular in the flying lemur and opossum, which are sup-
posed to live much on animal substances.

The coecum of the true carnivorous mammalia is constantly small,
and uniform in its cavity; and the rest of the large intestine has the
same characters. 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 coecum shews that the animal feeds 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 ornithorhynchus paradoxus, pt. 2, of
the ornithorhynchus hystrix.

§ 112. In most herbivorous animals of this class, the colon
is large, long, and divided into cellular compartments. This
is remarkably the case in the elephant and horse. The large
intestine of the latter is twenty-four 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 con-
tract it, and render the evacuation of the faeces difficult.

In a few instances, as in the beaver and sloth, but most re-
markably in the ornithorhynchus, the rectum and urethra have
a common termination, which may be compared to the cloaca
of birds.

As we have spoken above of the bezoars and other concre-
tions formed in the stomach, we must here take notice of the
intestinal stones which occasionally occur in horses, and of
the valuable faecal concretions of the pike-headed 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 ap-
pearance; when broken, not very hard; and in their ave-
rage 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 remarkable circumstance
relating to them is their composition; according to Fourcroy’s
and Klaproth’s Analysis, they consist in the proportion of one
half of phosphate of magnesia. They are often found in
[Seite 117] 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. They are not discovered in ge-
neral until the death of the animal; but I find an instance, in
the Epistolae de Re Numismatica 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
coecum of the horse. It is composed of fine vegetable fibres,
and resembles, on the first view, the balls of the chamois.
Hence Lafosse, who has described and delineated them, calls
them aegagropilae, by way of distinction from the true intes-
tinal stones, which he terms bezoar equinum.* Like the balls
of the chamois, they are much lighter than intestinal stones;
and two of them are not unfrequently found together, one
being inclosed within the other.

The faecal 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 Joseph Banks informed me, that according to
what he could learn from the English South-Sea whalers, the
faeces of the cachalot, which are nearly fluid in a healthy
state, are hardened into this ambergris by a kind of constipa-
tion; hence it is only found in weak and exhausted animals,
and the firmest and most valuable comes from such as seem to
have died of the complaint which it has occasioned.

birds.

§ 113. The alimentary canal in birds is much shorter than
in the mammalia; it is also generally shorter in carnivorous
[Seite 118] 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 commence-
ment of the canal is often larger than the termination.

§ 114. Most birds have two coeca, which are of considerable
length in some species of the gallinaceous and aquatic tribes.
They are characterized in the ostrich,* by a remarkable spi-
ral valve. Some few aquatic birds have only a single coecum;
and some, particularly among the birds of prey, want it en-
tirely.

§ 115. The rectum ends in a part called the cloaca, which is
an expanded portion, containing the termination of the ureters,
the genital organs, and the bursa Fabricii. This latter part
varies in form in the different species, being oval or elongated,
&c.; it is largest in young birds, and is so contracted in older
ones, that it will hardly hold a millet-seed in an old cock. In
the ostrich the cloaca forms a large spherical bladder; a si-
milar structure is observed in the goshawk and in the grey
heron.

The bursa Fabricii is an oval membranous bag, situated at the up-
per or back part of the cloaca, into which it opens by a slit-shaped
aperture. Its size is proportionate to that of the animal; being one
inch and a quarter long in the goose, and half an inch broad; and
about a quarter of an inch long in the sparrow. According to the
accurate observations of Mr. Macartney, its coats contain numerous
glandular bodies which furnish a mucous secretion. (Article Birds
in Rees’s Cyclopedia.)

amphibia.

§ 116. 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 hawks-bill turtle (testudo caretta)
is five times as long as the whole animal; the small intestine
is larger than the short portion of large intestine. Both por-
tions have longitudinal folds internally, and are covered with
an abundance of mucus, which is the case in the whole class.
[Seite 119] I found these folds so large and numerous in the rectum, that
a transverse section of the gut presented the appearance of a
broad radiated ring.

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.

§ 117. In the ringed-snake, (coluber natrix) the whole
length of the intestinal canal does not equal that of the ani-
mal. The small intestine forms a very considerable fallopian
valve,
by a prolongation at its entrance into the large. The
termination of the small, as well as the large intestine, the sto-
mach, and the oesophagus (which is one third of the length of
the whole animal) have longitudinal folds* internally.

fishes.

§ 118. The intestinal canal of this class, with a very few ex-
ceptions, is extremely short. In some, as the torpedo, it is only
half as long as the stomach. 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 valve.

In the structure and formation of the coats of the intestinal canal
there are not many differences in the mammalia. True valvulae conni-
ventes
seem peculiar to man and the monkeys. But the internal sur-
face 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 coecum, 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
[Seite 120] the lower portion of the small intestine, and are very visible on ac-
count of their colour.

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

The villi in the small intestine of birds are remarkably long, nu-
merous, and elegant. They are most distinct 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 uni-
form 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 innumerable thin longi-
tudinal 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 ali-
mentary matter becomes deprived more and more of its nutritious
parts, as it descends in the intestine, a less complicated 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 circum-
stance is illustrated in the longitudinal folds of the cetaceous animals.
At the commencement 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.

§ 119. 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, but generally at the com-
mencement of the intestinal canal, and secrete a fluid, which
seems to have considerable influence on the business of diges-
tion and chylification,* which is performed in these animals in
a very short time. They have generally the appearance of
small blind appendices, and their number varies in the differ-
ent species, from one to several hundred. In some cartilagi-
nous fishes they are as it were consolidated into a glandular
[Seite 121] body,* which has been compared to the pancreas of warm-
blooded animals.

insects.

§ 120. Similar blind appendices (vasa varicosa of Swam-
merdam) are found on the short alimentary canal of several
insects, which is particularly distinguished from that of red-
blooded animals by the want of mesentery. Some zootomists
have considered these appendices as small intestines, others
as biliary ducts, and others as lacteal vessels.

vermes.

§ 121. Several mollusca have these appendices on both sides
of their short intestinal tube, as the aphrodite aculeata.
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 inha-
bits a shell, (helix) the rectum opens on the front of the lim-
bus,
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 faecal matter is discharged, most of this
being evacuated by the mouth. The armed polypes have no
opening of this kind.

As the part of his work which the author has devoted to the ali-
mentary 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 sub-
join a somewhat more ample account.

The simple globular hydatid, which is frequently found in the dif-
ferent viscera both of man and quadrupeds, has been supposed by
some to be an animal consisting entirely of a stomach. Doubts, how-
[Seite 122] ever, have lately been raised, whether 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 Hy-
datids grow and multiply in the Human Body,
”’ by John Hunter, M.D.
in the 1st vol. of the Transactions of a Society for the improvement of
Medical and Chirurgical Knowledge;
and the note to the 83d para-
graph of this work. Even if it were allowed that these bags are ani-
mals, it does not follow that their cavity is a stomach; and the at-
tachment of the young to the sides would rather justify us in consi-
dering it as the organ of generation.

The hydatid, which is more frequently found in 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 independent vitality. But whether
the bags of water, which form its body, be a stomach, is certainly
doubtful.

The most simple form of an alimentary cavity exists in the com-
mon fresh-water polype (hydra). It appears to be excavated in the
substance of the body, and has a single opening, situated in the cen-
tre 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 structure. 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 suc-
cessive 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 remarkable analogy to the roots of
trees; and Cuvier has formed a new genus under an appellation de-
rived from this comparison; viz., the rhizostoma, from ῥιζα a root,
and στομα a mouth.

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

The tape-worm (taenia) has a small canal running 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 simple 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 perforated in the centre. It has been generally supposed
that this animal has no anus; but Cuvier says that it possesses a
[Seite 123] very small one. (Leçons d’Anat. comp. tom. iv. p. 141; Dumeril,
on the contrary, denies its existence. Zoologie Anatomique, p. 298.)

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

The aphrodite aculeata has an intestine running according to the
length of the body, and sending off on each side several blind pro-
cesses which enlarge at their termination.

In the proper mollusca, besides the stomach, which has been al-
ready noticed, there is an intestine, seldom of considerable length,
making some turns in its course; it passes, in all the acephalous mol-
lusca,
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 larvae of beetles (scarabaei) and
butterflies have intestines ten times as large as the winged insects,
which are produced from them.

In the dragon-fly, (libellula) which is very carnivorous, the intes-
tine is not longer than the body. There is a small but muscular sto-
mach.

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

The alimentary canal runs straight along the body in the crustacea,
and is uniform in its dimensions, excepting the stomach.

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

[Seite 124]

§ 122. We may conveniently collect together, in this chap-
ter, 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 constantly found
in the animal kingdom than the liver, and to be in a manner
subservient to the latter viscus; which, on the contrary, exists
in every class and order of animals that is provided with a
heart and circulating system.*

mammalia.

§ 123. Besides the less important variations in size, colour,
division into lobes, &c., the liver of these animals is distin-
guished by two chief differences; first, in some genera and
species it transmits all the bile immediately into the duodenum.
Secondly, in several others a part of this fluid is previously
collected in the gall bladder. Animals of the horse and goat
kind, and some of 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
[Seite 125] the liver into this bladder, as in the horned cattle. 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 poi-
sonous or noxious qualities when employed for food. Heems-
kerk’s companions experienced this in the former instance at
Nova Zembla; and Lord Anson’s squadron in the latter, on
the coast of Patagonia.

In the ox and sheep the spleen is distinguished by a pecu-
liar cellular* structure from the merely vascular texture which
it possesses in other animals of this class. Perhaps this differ-
ence in texture may lead to the discovery of the true functions
of this viscus, the use of which is at present unknown.

Mammalia alone possess a true and proper omentum; and
the part which has been called a spleen in other animals is
very different in its structure, connexions, &c. from the same
viscus as it exists in this class. I quote only a single instance
of the peculiar appearances of the omentum in particular spe-
cies; viz. that of the racoon, (ursus lotor) which has a very
remarkable structure. It is comparatively large, and consists
of innumerable stripes of fat, disposed in a reticular form, and
connected by an extremely delicate membrane, resembling a
spider’s web. I have also found it particularly large in an old
lioness.

The liver of mammalia is in general divided into more numerous
[Seite 126] lobes, and the divisions are carried deeper into its substance, than in
the human 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 pa-
chydermata,
and whales, the liver is not more divided than in man.

The ductus choledochus forms a pouch between the coats of the in-
testine, for receiving the pancreatic 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 tardi-
grada;
the elephant and rhinoceros, among the pachydermata; the
genus cervus and camelus among the ruminating animals; the so-
lipeda;
the trichecus and porpoise also want this part. It does not
exist in the ostrich and parrot, but is found in all the reptiles. Cu-
vier thinks that it belongs particularly to carnivorous animals; that
it is connected with their habit of long fasting, and serves as a reser-
voir 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. (Leçons d’Anat. comp. tom. iv. p. 37.)

The valvular transverse folds of the cystic duct belong only to the
simiae, besides the human subject.

The spleen of the ornithorynchus hystrix is composed of two lobes;
the anterior somewhat long and thick, the posterior broader and thin-
ner. Both run obliquely towards the right side to meet at an acute
angle in the left hypochondrium. The texture is loose and spongy.
See Meckel De Ornithorhyncho paradoxo, p. 46, Lips. 1826.

birds.

§ 124. The liver is much larger in domesticated than in
wild birds.* It is well-known that the gall-bladder is want-
ing in many species of this class, (for instance in the pigeon,
parrot,
&c.) and sometimes in particular individuals of a spe-
cies, which commonly has it, as in the common fowl.

A roundish lump of fat, which covers the intestines of some
aquatic birds, has been considered as an omentum.

The liver of birds is divided into two equal lobes. The hepatic
duct opens separately from the cystic, and its termination is generally,
[Seite 127] but not always, preceded by one or more pancreatic ducts, and fol-
lowed by that of the cystic duct.

The fundus of the gall-bladder receives branches from the hepatic
duct, but that tube sometimes unites with the cystic, as in the
duck.

amphibia.

§ 125. The liver, in these animals, is universally of consi-
derable size; and in some instances, as the salamander, of im-
mense magnitude. I know no species in which the gall-bladder
is wanting.

The yellow appendices (ductus adiposi, appendices luteae)
which are found in the frog, on either side of the spine, above
the kidneys, and sometimes form one mass, sometimes are di-
vided into several smaller portions, were considered by Mal-
pighi as a kind of omentum.* That this resemblance is very
remote, appears from several circumstances; and particularly
from the constant and remarkable variations of size which oc-
cur in these parts at the pairing season.

In the tortoise the liver has a peculiar conformation. It is divided
into two round irregular masses, of which one occupies the right hy-
pochondrium, and the other rests on the small curvature of the sto-
mach. Both are connected by two narrow branches of the same
structure, into which the principal vessels run. In the green lizard,
in the geckos, dragons, iguanas, it forms only a single mass, flat or
convex below, and concave above. Its free edge in the dragons has
two fossae, which divide into three lobes, of which the right is pro-
longed into a sort of tail. In the geckos it has only one fossa, and
the right side is also longer than the left. In the common iguana it
extends into a long appendix. In the crocodiles and chameleons the
liver has two distinct lobes. In the latter it has also a long appendix.
It has but one lobe in the serpent tribe, in which it is long and cylin-
drical. There is but one also in the salamanders, but there are two
in the frog genus.

fishes.

§ 126. 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
[Seite 128] 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.

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 glandulosus; 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 uniformly situated in
fishes.

The size of the liver is generally very considerable; its colour is
frequently yellower than in reptiles, and its divisions are as uncertain
as in the three preceding classes, so that they frequently vary, even
in the different species of the same genus. Its consistence is also
less compact than in the three classes; hence its parenchymatous
texture readily dissolves in spirits of wine, and leaves the vessels of
the liver exposed. In general its divisions are few; very frequently
it only forms one mass, sometimes however it has two lobes, occa-
sionally three, but very seldom more.

It rarely happens that the different branches of the hepatic ca-
nals unite in one duct, they open successively into the gall-bladder
or its canal, whence the whole of the bile is conveyed into the intes-
tine. The diameter of the cystic duct is always much larger than
that of the hepatic, but its size does not increase after its junction
with the other ducts. In the rays the gall-bladder receives several
very fine hepatic canals; afterwards the hepatic canal furnishes a
principal branch, which comes from the middle lobe of the liver,
and joins the cystic duct at a short distance from its origin. The
different branches of the hepatic canal unite in the syngnathus pelagi-
cus
into one trunk, which joins the cystic duct. In the tetrodons, the
hepatic canals have three principal branches, the first of which joins
the gall-bladder, a little on one side of its neck, and the second and
third open into the cystic duct, a little beyond its origin.

insects.

§ 127. An organ secreting bile, and which 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
cancer.* We have already observed, that the blind appen-
dices found in several others, have been considered as biliary
organs.

[Seite 129]

The large adipose substance which occupies the greatest
part of the body of larvae, and of several insects, has appeared
to some zootomists to resemble the omentum.*

vermes.

§ 128. 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-bladder.

Several testacea, particularly among the bivalves, have a
liver surrounding their stomach, and pouring its bile into the
cavity of that organ. In many snails it occupies the upper
turns of the shell.§

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 alimentary 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 struc-
ture.

In the acephalous division of this class, it surrounds 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.

The author has entirely omitted speaking of the pancreas in this
part of his work; probably because there are no remarks of much
[Seite 130] importance or interest to be made on the subject. The structure 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 ductus choledochus. In the mammalia they generally open to-
gether, or there is a branch terminating in the ductus choledochus,
and another 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 separate or distinct in different individuals of the same
species, as in the monkeys.

The skate and shark have a pancreas similar to that of the three
first classes of red-blooded animals. In other fishes the situation of
this organ is occupied by the coecal appendices or pyloric coeca; which
afford a copious secretion, analogous, no doubt, to the pancreatic
liquor. (These are mentioned in § 119.) 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 mass, which is surrounded by mus-
cular 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 131]

§ 129. These emunctory organs do not exist in several ani-
mals 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.

mammalia.

§ 130. In some animals of this class, as the bears,* the kid-
ney resembles a bunch of grapes, being composed of several
small and distinct portions, which are connected by means of
their blood-vessels and ureters with the common trunks of
those vessels. In many of the palmata, as the seal and the
otter, the renal veins form a kind of network, the reticulations
of which intersect the furrows between the mammary pro-
cesses on the outer surface of the kidneys. The suprarenal
glands, (glandulae suprarenales) as their name implies, are
intimately connected with the kidneys; but their functions, as
well as those of the thyroid and thoracic glands, still remain
unknown. They appear, from the latest anatomical re-
searches, to have a great sympathy with the sexual organs.
The urinary bladder is more loose§ in the abdomen of most
quadrupeds than in the human subject. It is comparatively
much smaller in carnivorous than in herbivorous animals; and
is particularly large in the ruminating bisulca and the hare.

[Seite 132]

Urinary stones, often of very considerable size, are found
not unfrequently in horses, whose intestinal concretions have
been already noticed. Their composition differs considerably,
according to the investigations of Fourcroy and Vauquelin,
from the urinary stones of man; since they contain neither
phosphoric nor lithic, but carbonic acid.

The structure of the kidney in mammalia displays two very oppo-
site varieties, which may be called the simple and the conglomerate
kidneys. In the former there is a single papilla, which is surrounded
by an exterior crust of the cortical substance. 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 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 states that it belongs to all the
whales. (Philos. Trans. 1807, pt. 2.) The otter has the same struc-
ture; 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 remarkable 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 Academicians;
which is also given in Blasius’s Collection. Anatom. Animal. tab. 32,
fig. 2, 3, 4.)

birds.

§ 131. The kidneys* of this class (with a few exceptions,
as the cormorant, &c.) form a double row of distinct but con-
nected glandular bodies, placed on both sides of the lumbar
vertebrae, in cavities of the ossa innominata; one of the most
instructive examples of the remarkable analogy between the
structure of the secreting viscera, properly so called, and the
[Seite 133] conglomerate glands.* The urinary bladder is wanting in
the whole class, and the ureters open into the cloaca.

amphibia.

§ 132. Animals of the genus testudo and rana have an uri-
nary bladder, which is double in many 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.

The two large bags, which the author, and also Cuvier (Leçons
d’Anat. comp.
tom. v. p. 237) represent as urinary bladders of the
frog and toad, are stated by Townson to have no connexion 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.

fishes.

§ 133. The glandulae suprarenales are wanting in this class;
and they seem therefore to be confined to such animals as
breathe with lungs. Although 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.

CHAPTER X.
ON THE EXTERNAL INTEGUMENTS.

[Seite 134]

§ 134. Among the various objects and functions of the com-
mon integuments, as they are called, one of the most import-
ant, and most general, in red-blooded animals, is the office
which they perform as emunctory organs. Hence we may in-
troduce here with propriety what we have to say on the sub-
ject.

§ 135. 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 texture. 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. The rete mucosum lies between these; but it can
only be shewn, as a distinct layer of the skin, in warm blooded
animals. Lastly, the cuticle is furnished in the different
classes with peculiar organs for the formation and excre-
tion of particular matters, viz. hairs in mammalia, feathers in
birds.*

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

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 branny ap-
pearance.

It is in the rete mucosum that the colour of the skin resides; but
[Seite 135] this part possesses, in very few instances, any brilliancy of colour
in the mammalia. 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 remarkably thick on these animals; being about the
sixteenth of an inch on the back, and such parts as are of a black co-
lour.

The vascular net-work, says De Blainville, in the work referred to
by Blumenbach, which is situated immediately over the cutis, occu-
pying its whole surface, is in general of an exceedingly thin texture;
it is formed entirely of arterial, venous, and lymphatic vessels, which
undergo many complex ramifications and anastomoses; this net-work
is spread over the projections situated on the surface of the cutis. The
pigmentum does not perhaps exist in all animals; it forms at the sur-
face of the vascular net-work a layer more or less defined, of slight
consistence, semi-fluid, and in effect composed entirely of very mi-
nute grains, agglutinated to each other, without any organic conti-
nuity between their own particles or with the other portions of the
skin; it is a sort of artificial membrane or depository, which is va-
riously coloured, and which seems to be exhaled by the parietes of
the veins. This pigmentum and the vascular net-work are both crossed
by the nervous extremities which meet at the surface of the skin, some-
times under the form of papillae. These two parts of the skin are
those, which, since the time of Malpighi, have been known by the
name of Malpighi’s net-work, corpus reticulare, reticulum mucosum, on
account of the sort of net-work which they form for the passage, not
only of the nervous papillae, but also of the accessory parts. They
are both in my opinion, says De Blainville, the source of the colour-
ing matter, and the pigmentum is the depository of that matter.

The colour of the skin is different in the inhabitants of different
countries; in some it is white, in others brown, yellow, red, and
black. This variety depends on something peculiar in the constitu-
tion, and in no way on climate; it arises just from the same cause as
the difference in the colour of plants and animals. This is proved
by the fact of the Negro and American children being born with the
colour peculiar to the respective races, as well as by the peculiar
organization of the skin. Humboldt says, that the children in Peru,
Quito, on the coast of the Caraccas, on the banks of the Orinoco,
and in Mexico, are never white at the time of birth; and the Indian
caciques, who are well provided for, and live in houses, are of a
reddish brown, or copper colour, all over the body, with the excep-
tion of the palm of the hand and sole of the foot. Vid. Rudolphi’s
Physiology, by Dunbar Howe, § 43.

mammalia.

§ 136. 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 exceedingly thick in the rhinoceros, elephant, &c.
[Seite 136] also in the web-footed animals, particularly the walrus.* 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 sometimes threadlike, as on the
paws of the bear, and are very elegant on the teats of the true
whale (balaena mysticetus). I have also observed this in se-
veral macacos (simia cynomolgus) and mandrils (papio mai-
mon
).

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.

I have had an opportunity of examining the skin of the ce-
tacea in a balaena boops, and in a dolphin (delphinus delphis).
In both the rete mucosum was very thick; but by no means
equal to the breadth of a finger, as is represented in a whale of
uncertain species in the Museum Gaubianum.

In some spotted domestic animals, particularly 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.

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 co-
vers the callosities on which they sit. In various multungula,
particularly the elephant, it forms a kind of horny processes,§
lying close together in several parts of the body. But diffe-
[Seite 137] rences of this kind are too numerous to admit of their being all
noticed in this work.

Villi, or papillae of the skin are found on those parts which corres-
pond to the toes and fingers 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.

§ 137. Hairs, at least single ones, are found in all adult
mammalia, even without excepting the cetacea. In various
states of thickness and strength they constitute every inter-
mediate substance, from the finest wool to the strongest quills
of the porcupine. Thick bristles, and hairs, as they are found
for instance in the tail of the elephant and other animals, re-
semble horn, or fish-bones in texture; while, on the other
hand, both these substances 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 ornithorhyn-
chus
and the common porcupine. Others, as the whiskers of
the seal,* are also flat, but have rounded and denticulated
margins, so that they have a kind of knotty, or jointed appear-
ance. Something similar may be observed in the hair of some
cloven-hoofed 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 tex-
ture, and consequently 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 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
[Seite 138] 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.* It is electrical in some species, and serves in those ani-
mals which possess much of it, as a mode of excreting super-
fluous phosphoric acid.

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

The skin secretes a matter of peculiar odour in some races. ‘“The
Peruvian Indians,”’ says Humboldt, (Political Essay, i. 245) ‘“who in
the middle of the night distinguish the different races by their quick
sense of smell, have found three words to express the odour of the
European, the Indian American, and the Negro; they call the first
pezuna, the second posco, and the third graco.”’ He adds, ‘“that the
casts of Indian or African blood preserve the odour peculiar to the
cutaneous transpiration of these primitive races.”’

The following quotation from the 2d chapter of the author’s Ma-
nual of Natural History (Handbuch der Naturgeschichte
) explains the
terms made use of in the foregoing paragraph, represents the sub-
ject in an interesting point of view, and contains 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 viewed in connexion with the system of growth altogether, it
constitutes one of those grand characters which distinguish the ma-
chines that proceed from the hand of the Creator, from all the pro-
ductions of human skill. The springs and wheels of mechanical in-
struments have no power of repairing themselves when injured or
worn; but such a power, in different degrees, is imparted to every
animal and plant.

At different periods of the year several organized beings lose by a
spontaneous and natural process certain parts of their body, which
[Seite 139] are subsequently renewed. Examples of this occur in the fall of the
stag’s horns; in the moulting of birds; in the renewal 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 reproductive power is that
by which wounds, fractures, or any accidental mutilation or loss of
parts of an organized body are remedied or restored. Man indeed,
and such animals as are nearly allied to him, possess this property in
a very limited degree, while its strength and perfection are truly asto-
nishing 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 polypes, (hydra) &c.

Some experiments on this reproductive power require a hand ex-
ercised in such employments, together with various precautions, and
a favourable combination of circumstances, for their success. Hence
persons must be cautious in concluding against the truth of any state-
ment, because their own experiments do not succeed. After several
fruitless 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 discharged, 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
distinguished from the same organ on the opposite side by being
smaller. See the Gottingen Literary Notices for 1787, pp. 28, 30.

birds.

§ 138. The integuments of birds have the 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 struc-
ture of their roots, to the formation of feathers; the universal
and peculiar covering of this class of animals. The particular
differences in the formation of the feathers are innumerable.*
Among the most remarkable are the small scale-like feathers
(squamulae ciliatae) 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 Bo-
[Seite 140] hemian chatterer
(ampelis garrulus). Several birds in differ-
ent orders have two or more feathers arising from a common
quill.

In a young ostrich, which had just quitted the egg, and which
now lies before me, there are as many as twenty feathers on the
back, proceeding from a single barrel.

In the encysted tumours of the ovaries, large collections of
hair are not unfrequently found, and in the thoracic and abdo-
minal viscera of tame geese and ducks preternatural formations
of feathers, covered over with a kind of fat, are also met with.*

The periodical renewing of the feathery covering, 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 afford-
ed 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; viz. that as the latter
ceases in her old age to lay eggs, she obtains the male plu-
mage.

Lastly, the integuments of birds serve the office of emunc-
tory organs, which is proved even by the process 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.

amphibia.

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

[Seite 141]

The 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 sim-
ple skin, as some frogs, change their colour occasionally, either
from difference in the light or warmth, or from the effect of
their passions.

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 compared to
a bag containing the animal.

The reflection of coloured objects on the glittering scales of the
chameleon, probably gave origin to the fable that its colour is regu-
lated by that of the bodies near which it is placed.

fishes.

§ 140. All fishes, without exception, are covered 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 remark-
able that the colour of the skin in some fishes, as for instance,
the mullet, (mullus barbatus) depends on that of the liver.*
The scales are not changed like hair and feathers, but are pe-
rennial; 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.

The lower orders possess in general an epidermis. In the testacea
it usually covers the surface of the shell, and obscures the brilliancy
of that part until it is removed. It may be seen by plunging a snail-
shell into boiling water. It is very thick and villous in some species,
as in the arca 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 bom-
byces.

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

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

[Seite 142]

If one of the large hairs, which grow on particular 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 measure by that of the
rete mucosum, and this circumstance is particularly observable in the
human 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 altogether. 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 co-
vered with a very long and peculiar kind of hair in Angora, a small
district of Asia Minor, and the superior 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 finger. They consist of a solid, insensible, and elastic
substance, which in many cases has a fibrous appearance, as if it were
composed of an aggregation of hairs. This structure is most parti-
cularly remarkable in the rhinoceros, where the horn is solid, and
situated over the nasal bone. The fibres analogous 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 concep-
tion. This being 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 additions to its
base and internal surface.

The nails and claws of animals are formed just like horns, they co-
ver a process of the last phalanx, which is analogous to the frontal
process of the horn, and grow from the root or base, to which the in-
teguments are attached, while they wear away at the loose edge.

The hoof of the horse, ass, &c. is a horny covering of the last pha-
lanx; similar, in its structure and formation, to the parts just men-
tioned, but including 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 corresponding laminae of the vascular sub-
stance, and constitute a most close connexion between the two parts.
[Seite 143] 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. Fasciculi 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. The opposite end receives those blood-
vessels, which supply the vascular substance in the barrel of the fea-
ther; when the stalk of the feather has received its complete growth
this vascular body is dried up, and presents the well-known appear-
ance in the barrel of quills.

The parts which have just been described, as well as the epidermis,
and the scales, or rather hard coverings 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 conveyed to the subjacent living parts.

CHAPTER XI.
ON SEVERAL PECULIAR SECRETIONS.

[Seite 144]

§ 141. It is necessary that we should take notice 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 ani-
mals, and may be most conveniently considered here, at the
end of that division which treats of the natural functions.*

mammalia.

§ 142. Besides the well-known salivary glands, there is an-
other, which has been described by Nuck in the orbit, par-
ticularly of the dog, and some other predacious animals, which
has an excretory duct opening near the last tooth of the up-
per jaw. Professor Jacobson has described a remarkable
secreting gland, which is situated in man and in many other
mammalia, and probably in all birds, on the external side of
the nostrils, the excretory duct of which opens at the anterior
extremity of the lower concha. He names this organ after its
illustrious discoverer, la glande nasale de Stenonis.§

§ 143. Both sexes of both species of the elephant, viz.
the African and Indian, have a considerable glandǁ 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 skin.

[Seite 145]

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 pecari (sus tajaçu).

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 an 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. (Bartholin. Cent. 2, Hist. Med. 96.)

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

§ 144. Several ruminating bisulca, and the hare, have on
the outer side of the upper jaw, near the ossa nasi, sebaceous
sinuses,
which have received that name from the adipose and
viscous substance which is separated there in great abun-
dance in some animals, and which is well known in the stag,
where it is supposed to be of a lacrymal nature.*

§ 145. In most of the ruminating animals, and in the hare,
there are cavities in the groins, near the genitals, called by
Pallas antra inguinalia, and containing a strong-scented seba-
ceous substance secreted from glands which lie under the in-
teguments.

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

[Seite 146]

§ 147. There are also, in the badger and the opossum, as
well as in several other carnivorous animals, (both among the
digitata and palmata,) peculiar glands and bags at the end of
the rectum, secreting a yellow substance of a strong and disa-
greeable smell in its recent state, and which frequently gives
to their excrement a kind of musk-like odour.*

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 parti-
cularly to the carnivorous animals. They may be seen very well in
the cat. Their secretion possesses that strong disagreeable odour
which characterizes so remarkably many animals of this order, as the
fox and all the weasel tribe, and which has even made the polecat
proverbial in common language, and has bestowed on it its scientific
name, mustela putorius. 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.

§ 148. These anal glands must be distinguished from ano-
ther kind of similar glands and bags, which also secrete
strong-scented matters, but seem to be rather connected with
the genitals. These are found in some of the same carnivo-
rous animals which possess the anal glands, as the lion, the
civette, &c.; also in many herbivora, which want the latter or-
gans; in some of whom they exist in both sexes, as in the
beaver, the ondatra,§ (mus zibethicus) &c.; in others they
are peculiar to the male, as in the musk animal,ǁ whose pouch
is found in the prepuce near the navel.

[Seite 147]

It is from these glands, and not from the testicles, as naturalists
have absurdly supposed, that the substance called castoreum is pro-
duced. A delineation of the parts, from the dissection of the Pari-
sian 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 moschus moschifer, (the musk) an animal
found in the mountains of Thibet, and the southern parts of Si-
beria.

§ 149. We must also mention here the glandular cavities,
covered internally with hair, which are found in the feet of
several ruminating bisulca, and particularly in the sheep.
They have an excretory duct opening at the junction of the
toes;* and the obstruction of this, particularly from a long
continuation of wet weather, occasions troublesome symptoms.

birds.

§ 150. Although birds do not masticate their food, several
of them, particularly among the pici, have considerable sali-
vary glands
at the sides of the lower mandible. The secre-
tion of these glands serves to facilitate the numerous and
strong motions performed by the tongue in deglutition.

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

It has been already stated that salivary glands, in the proper
sense of the term, do not exist in birds, and that the parts which
the author mentions here must be regarded in a different point of
view.

§ 151. 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.

amphibia.

[Seite 148]

§ 152. I do not think it probable that the part which has
often been considered as a pancreas in this and the following
classes of animals, really deserves that name. Zootomists
have not been able to agree on this point; Charas took that to
be the pancras of serpents, which Tyson with the ancients
called the spleen.

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 rattle-
snake.*

§ 153. An acrid fluid exudes through numerous 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 dangerous kind of poison formed in some serpents,
which are distinguished from the innocent ones by the organs
pointed out in a former part of this work.

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.

There are situated on the heads of most serpents five pairs of
glands; the first is a small, long, round, and very hard gland, si-
tuated at a very little distance from the skin, close behind the ante-
rior extremity of the lower surface of the mouth. These may un-
doubtedly be compared to the sub-lingual glands of other animals.
Cuvier has found them in the amphisbaenae, where they are in propor-
tion the largest; but neither he nor any other author mentions their
existence in the other species, although with the exception of the
typhlops, I found them in all the species which I examined.

The second is situated more behind, and to the inner side of the
eye: in general it is of a considerable size, and of a white soft colour.
Meckel found them in the amphisbaena alba and fuliginosa; also in
the eryxjaculus, tortrix ocytale, elaps, they are very considerable. They
are generally situated without and behind the orbit, particularly in
[Seite 149] the coluber, tortrix, and eryx, but in the boa, python, and poisonous
serpents, part of the gland lies within the orbit.

The third, which is not so common as the two preceding, is a
gland of some length, and situated close to the rami of the lower
jaw; there are numerous excretory ducts, which open externally
through the teeth of the lower jaw, in a simple longitudinal row.
Cuvier has described them in the coluber and boa; afterwards Tiede-
mann and Cloquet gave delineations of them as they are found in the
coluber natrix, and Rudolphi as they are found in the vipera vera;
they have since been found in several other species of serpents. They
correspond in their form, structure, and situation, to the buccal and
labial glands of mammalia.

The fourth is situated externally, close to each side of the upper
jaw. In the vipera dubia Meckel found a small gland at the corner
of the mouth; Tiedemann found them in the anguis, although Meckel
who examined three fine specimens was not able to detect them. In
the coluber, amphisbaena, tortrix, and eryx, this gland is very consider-
able; in the python, crotalus, vipera vera, they are of moderate size; in
the elaps they are extraordinarily small, and intimately connected
with the excretory ducts of the poisonous glands situated beneath them.

The fifth are the poison-glands: these are the most remarkable,
and it is difficult to conceive how they could have been overlooked
by the earlier anatomists. They are situated above the upper jaw,
behind and below the eyes; they are surrounded by a very strong
muscle, and in fact embedded in it, so that they cannot be seen until
the muscle has been divided. They are of some length, and have a
laminated texture; internally they have a considerable cavity, and
are distinguished from all the other glands by a very long excretory
duct which takes its course along the outer surface of the upper jaw,
and opens above and before the poison teeth in such a manner into
the sheath, that the poison flows into the upper opening of the tooth.

Meckel has come to the following conclusions on the number and
proportional size of the glands of serpents.

1. Several poisonous serpents, viz. the crotalus, naja, vipera vera,
elaps lemniscatus,
possess the greatest number of glands; for, in ad-
dition to the poison and salivary ones, they also have five pairs.

2. Four pairs only exist: 1, in the vipera dubia, for besides the
poison glands, they have merely the lachrymal and lingual, and a
slight rudiment of the labial at the angle of the mouth; and 2, in the
coluber python, amphisbaena, there are also only four pairs.

3. The anguis fragilis has four pairs, the upper labial glands only
being wanting; but in the trigonocephalus both pairs of the labial
glands are wanting.

4. Lastly, in the typhlops crocotalus, all or nearly all are wanting.

5. Those serpents which have no poison glands possess all the
others in a greater state of development. Both the poison and other
glands have excretory ducts. Vid. Meckel’s Archiv. fur Physiologie,
Lip. 1826.

fishes.

[Seite 150]

§ 154. The most universal secretion in this class, which
comes under the present chapter, is that of the mucus, which
besmears their skin and scales, and which is formed in canals*
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 discharge.

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. (Leçons d’Anat. comparée, tom. v. p. 260.)

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 accom-
panying the tubes.

For an account of the electrical organs of fishes, which must be
considered as parts secreting the electrical matter, see § 218; and
for their swimming bladder, in which a secretion of air is effected,
§ 187.

insects.

§ 155. There are no true conglomerate glands, nor analo-
gous parts in insects; but their different secretions are per-
formed by loose vessels. Besides the different secretions
of peculiar matters, which belong exclusively to single species,
as the vapour, which some carabi (carabus crepitans, margi-
natus,
&c.) discharge, and the strong odours with which seve-
ral of the bug-kind defend themselves in case of necessity,
[Seite 151] two kinds of secreted fluid deserve to be particularly remarked
in this class: the silk which is formed by the larvae of pha-
lenae* (moths) and by spiders; and the poison with which
several hymenopterous and apterous§ insects are armed.

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

Almost all the larvae or caterpillars spin for themselves some kind
of covering before their metamorphosis; but it is the silkworm only
(bombyx mori) that furnishes the materials of our various silk manu-
factures, 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.

In those insects which possess stings, the 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 con-
tained 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.

vermes.

§ 156. The most remarkable secretions in this class take
place in the testacea. There is one of these common to the
whole class; viz. the formation of the calcareous matter of
their shells,ǁ which takes place in a peculiar viscus lying near
the heart (sacculus calcarius, Swammerd. glandula testacea,
Poli). The celebrated purple colour is formed in some ma-
[Seite 152] rine genera; as the buccinum lapillus and echinophorum,
murex brandaris
and trunculus, helix ianthina, arca nucleus,
&c. Lastly, some bivalves, under extraordinary circumstances,
form pearls* on the inner surface of their shell.

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 produces 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.
Handbuch der Naturgeschichte, ed. 6, p. 438.)

The black inky fluid of the cuttle-fish, which has often been sup-
posed 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
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. Accord-
ing to Cuvier, the Indian ink, which comes from China, is made of
this fluid. (Leçons d’Anat. comp. tom. v. p. 262.)

THE VITAL FUNCTIONS.

[Seite 153] [Seite 154]

THE VITAL FUNCTIONS. CHAPTER XII.
ON THE HEART AND BLOOD-VESSELS.

[Seite 155]

§ 157. A perfect circulating system, to which on the one
hand fluids are brought by the absorbents, to be converted
into blood; and from which, on the other hand, various juices
are separated in glands, and viscera of a glandular structure,
appears to belong universally and exclusively to red-blooded
animals. A pericardium exists in all these animals. Parts of
such a system, particularly a heart, and certain vessels con-
nected with it, are found in some genera of the two white-
blooded classes. It is surprising that so many good anato-
mists, among whom are Blasius, Peyer, Harder, and Tozzetti,
should have denied the existence of a pericardium in the
hedgehog. The membrane is indeed very delicate in this
animal, and it requires some care to avoid tearing it in opening
the chest.

mammalia.

§ 158. The internal structure of the heart is the same as in
man; but its situation in quadrupeds and cetacea differs from
that which it has in the human subject. It is in the former
situated more longitudinally with respect to the body, resting
rather on the sternum than on the diaphragm. Hence the
pericardium of these animals, with a few exceptions, is not
connected with the diaphragm* as in the human subject; the
[Seite 156] portion of the inferior vena cava within the chest is propor-
tionally longer.

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.

§ 159. 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 ven-
tricle. The common notion, that they serve as a support to
the valves,* does not much elucidate the subject.

The right auricle receives in the porcupine and elephant two ante-
rior venae cavae; the left of which opens near the communication
with the ventricle.

§ 160. It has been supposed that the amphibious animals
of this class and the cetacea have an open foramen ovale, like
that of the foetus, in their septum auricularum. And the ne-
cessity of such an opening has been inferred from their way
of 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.

I possess a very singular heart of an adult seal, the foramen
ovale
and ductus arteriosus of which are completely open.
Both the arterial trunks, and particularly the aorta, form
large, and as it were aneurismatic expansions.

In several genera and species of web-footed mammalia, 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
[Seite 157] 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 respiration can be again performed, and the lesser*
circulation be thereby again put in action.

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 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. iv. p. 201.)
The Parisian dissectors also found it closed in a beaver. (Description
Anatom. d’un castor,
&c. p. 68.) It has been found perfectly shut in
a porpoise and young seal; and according to Sir Everard Home,
(Phil. Trans. 1802) it is closed in the ornithorhynchus. On the other
side of the question, besides the fact mentioned by Blumenbach,
which is very striking, we may adduce Sir Everard Home’s authority
for the existence of the foramen ovale in an open state in the sea
otter.
He found it so in two instances, one of which was in an adult
animal; but the ductus arteriosus was closed. (Philos. Trans. 1796,
pt. 2.) This may perhaps be nothing more than a casual occur-
rence; as a small opening is not unfrequently found in the human
subject, where no symptom of disease, or defect in the circulating
system has existed.

§ 161. There are some remarkable circumstances in the dis-
tribution of particular arteries in certain animals of this class.
We may notice, as the most singular of these, the rete mirabile,
formed by the internal carotid at its entrance into the cranium,
in several ruminating bisulca and carnivorous animals; and
that division of the arterial trunks of the extremities, which
has been observed by Sir A. Carlisle in the slow-moving ani-
mals, 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. The most curious and elegant
distribution of veins occurs in the foot of the horse; where
these vessels run in innumerable parallel branches on the an-
[Seite 158] terior surface of the coffin bone, and form a reticular plexus
of anastomoses on the under part which completely covers the
surface of the bone.

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, and in those which supply the me-
dulla spinalis and the eye. Hunter in the Philos. Trans. 1789, pt. 2.

birds.

§ 162. The whole of this class, without exception, possess
a very remarkable peculiarity in the structure of the heart.
The right ventricle, instead of having a membranous valve,
(such as is found in both ventricles of mammalia, and also in
the left of birds) is provided with a strong, tense, and 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 carbo-
nated blood in mammalia, does not take place in birds, on
account of the connexion which their lungs have with the nu-
merous air-cells, which will be afterwards described.*

§ 163. To this class, and also to those of amphibia and
fishes, Professor Jacobson ascribes a peculiar venous system,
by which the blood is carried from the posterior extremities
and from the sexual organs, not, as in mammalia, to the pos-
terior vena cava, but to the kidneys, or to the kidneys and
liver, for the purpose, as it should seem, of secreting the urine
in these three classes.

amphibia.

§ 164. The frogs, lizards, and serpents, of this country at
least, (Germany) have a simple heart, consisting of a single
[Seite 159] ventricle and auricle.* In others, as for instance crocodiles
and lizards, properly so called, and serpents, the heart con-
sists of one ventricle with two auricles.

The account which Cuvier gives of the anatomy of the heart in the
amphibia, does not exactly accord with that of the author. Cuvier
describes 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 structure, and that it obtains likewise in the serpents
(tom. v. p. 221–225). He does not mention the more simple form as
existing in any lizard or serpent.

§ 165. The structure of this part is very different in the
turtle; and has given rise to more controversy than that of
any order of animals. The heart of this animal possesses two
auricles, which are separated 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 pulmonary veins in the left. Each
pours its blood into the corresponding ventricle, of which ca-
vities there are two; thus the structure of the heart hitherto
resembles that of mammalia.

A remarkable difference exists in the structure of the auri-
cles between the testudo caretta and mydas, both of whose
hearts now lie before me. The auricles of the former are thin,
like those of warm-blooded animals; in the latter they are
very firm, and have almost as thick and strong parietes as the
ventricles.

The characteristic peculiarities which distinguish the heart
of these animals consist in three circumstances. First, the
two ventricles (and in some species of turtles, the cavities of
the auricles) are extremely small and narrow, but the fleshy
walls of this viscus are of a thick and spongy texture, so that
the heart has the appearance not so much of a double visceral
sac, as of a sponge soaked with blood. Secondly, both the
ventricles communicate with each other; there is a muscular,
and as it were tubular valve, going from the left to the right
[Seite 160] cavity, by means of which the former opens into the latter.
Thirdly, the large arterial trunks arise all together from the
right ventricle only; no vessel coming from the left. The
aorta, with its three principal branches,* is situated towards
the right side and the upper part; the pulmonary artery
comes as it were from a particular dilatation of the right ven-
tricle, which is not situated nearly in the middle of the basis
of the heart; (it must be understood, as we have already ob-
served, that we apply these terms according to the horizontal
position of the animal).

We can now comprehend how this wonderful and anoma-
lous structure, by which all the blood is propelled from the
right ventricle only, is accommodated 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 under water, and thereby
prevented from respiring, 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 obstruction of respiration
most immediately influences the greater circulation.

The best and most intelligible delineations of the turtle’s
heart are those given by Mery; although he made an errone-
[Seite 161] ous application of them to the course which he supposed the
blood to take in the heart of the human foetus. I conclude
from a comparison with my own preparations, that his draw-
ings were taken from the testudo caretta.

The natural structure of the hearts of these animals has a
striking analogy with the unnatural condition of this organ in
persons born with the morbus caeruleus. This phenomenon
with many others tends to shew that certain organs of the human
embryo, as well as the whole of its earliest formation, are sub-
jected to a kind of metamorphosis, the embryo first resembling
the structure of the lower classes of animals, before it reaches
the perfection of the human type. If during this change the
completion of any organ should be interrupted by any acci-
dental disturbance of the formative impulse, it remains in a
state which has a greater or less resemblance to that of an in-
ferior organization. Hence in many persons affected with the
blue complaint, the ventricles communicate with each other
by an opening in the septum, and both arteries arise from the
right, and none from the left.*

fishes.

§ 166. The heart in this class of animals is extremely small
in proportion to the body. Its structure 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
ventricle gives rise to a single arterial trunk (which is expand-
ed in most fishes into a kind of bulb as it leaves the heart), going
straight forwards to the branchiae, or organs of respiration.
The blood passes from these into a large artery, analogous to
[Seite 162] the aorta, which goes along the spine and supplies the body
of the animal; it is then returned by the venae cavae into the
auricle;* a proof, among many others, of the power which
the arteries possess of returning the blood, independently of
the action of the heart.

§ 167. Most cold-blooded animals, as fishes, and the am-
phibia of this country, (Germany) have a much smaller pro-
portion 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.

insects.

§ 168. A true heart, and system of vessels connected with
it, are found in a very few of what are called white-blooded ani-
mals. In this class they seem to belong only to some genera
of insects, which have no wings; as the genus cancer, and
monoculus. It has been proved by the excellent investigations
of Herold, that the long dorsal vessel of the larvae, &c. com-
municating an undulating pulsation, and carrying a kind of
ichor, is protected on each side by a flat triangular muscle,
and that it is an organ analogous to the heart. In the genera
which we have mentioned, there seems to be no passage of
the arterial extremities into the origins of veins, and conse-
quently no true circulation.

It appears that insects possess neither blood-vessels nor absorbents.
Cuvier has examined, by means of the microscope, all those organs
in this class, which in red-blooded animals are most vascular, without
discovering the least appearance of a blood-vessel; although ex-
[Seite 163] tremely minute ramifications of the tracheae are obvious in every part.
And Lyonet has traced and delineated in the caterpillar parts infi-
nitely smaller than the chief blood-vessels must be, if any such ex-
isted. 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 dilatations
and contractions 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 originate 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 consi-
dering, in a very different manner from that which obtains in the
more perfect classes. Cuvier expresses the mode, in which he sup-
poses growth and nutrition to be effected, by the term ‘“imbibition.”’
And he explains from this circumstance, the peculiar kind of respi-
ration 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 aller cher-
cher l’air, c’est l’air qui va chercher le sang.”’ (Leçons d’Anat. comp.
1. xxiii. 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 previ-
ously to its reaching the heart again. The different parts of the sys-
tem are here found under a mode of connexion 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.

vermes.

§ 169. In many genera of this class, particularly among the
mollusca,* and testacea, there is a very manifest heart,
[Seite 164] which is sometimes of a singular structure. It consists, for in-
stance, in the cuttle-fish, of one ventricle, and two auricles,
which lie at some distance from the ventricle, near the gills.
Some bivalves are said by Poli to have two auricles, and some
even four. But in all these crustaceous animals, there has been
no connexion hitherto discovered between the arteries and
veins;* while on the other hand some genera in other orders
of this class have a connected system of vessels without a
heart; and the proper zoophytes cannot be said to possess
either; as their nutrition seems to be effected by an imme-
diate derivation of the nutritive fluid from their abdominal ca-
vity into the gelatinous parenchyma of their body.

Baker, Fontana, Muller, and several other excellent natu-
ralists, have considered the dark portion in the body of the
wheel animal (vorticella rotatoria) to be a heart; although it
has voluntary motion, which is influenced by that of the radii,
and they have employed this circumstance by a curious petitio
principii,
to prove that there are animals which have a volun-
tary power of setting their heart in motion, or leaving it at rest.
I have shewn twenty-three years ago that this remarkable or-
gan can by no means be looked upon as a heart, but is really
an alimentary canal.

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, consisting of one auricle
and ventricle. The vena cava assumes the office of an artery, and
carries the returning blood to the gills; whence it passes to the auri-
[Seite 165] cle, 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 structure. This anatomist
is of opinion that the mollusca, crustacea, and vermes, possess no ab-
sorbing 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 intermediate 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.)

The comparison of the circulating system in different classes of ani-
mals constitutes one of the most interesting and important branches
of investigation in the study of comparative anatomy; and the stu-
dent should bear in mind that it was in the course of his inquiries into
the structure of the lower animals, that the immortal Harvey was led
to the discovery of the circulation of the blood. Much valuable in-
formation on this subject will be found in the lectures of Sir E.
Home, from which work we extract the following observations.

In animals that have no vascular system, consisting solely of a
membranous bag, there is much reason to believe no waste of mate-
rials takes place while in a quiescent state; indeed the facts which
Mr. Bauer has published in the Philos. Trans., respecting the worms
that form the disease in wheat called by farmers the purples, of which
Sir E. Home has taken notice in the first volume of his Comparative
Anatomy upon the Digestive Organs of Worms and Insects, completely
establishes this fact. Mr. Bauer has preserved some of these worms
in a dried state, and has found, that although they have been kept so
for six years, and even longer, when moisture is applied to them,
and they are placed in the field of the microscope, they revive in five
or six hours, and move with great agility.

The animals next in order to these worms, are other genera of
vermes, in which there is a circulation, but no heart: of this kind
are all caterpillars and insects. In them the blood does not circu-
late, and probably remains at rest at those times in which the animal
is in a quiescent state; but during the period of locomotion, or when
feeding, or using other muscular exertion, the blood undulates from
one end to the other of a large tube situated upon the back, at such
times supplying the different organs, and becomes aerated by the
air-vessels which pervade every part of the body.

Were animals classed according to the different modes of aerating
the blood, one great class might be formed of those animals, in which
the air circulates through the body, and the blood is confined to a re-
servoir; another, when the blood circulates through the body, and the
air is only applied to a particular portion of it.

[Seite 166]

The heart will therefore be found to be of less importance than it
has been generally considered, and only to be an organ met with in
some of the higher orders of animals.

When we consider the aeration of the blood in insects, it must be
greater than in other animals; and there is this curious circumstance,
arising out of the bodies being so abundantly supplied with air, as
soon as the cold is too great for their exerting muscular power, the
spiracula become closed, and the animal remains in a torpid state; by
any increase of the warmth of the atmosphere, the air retained in the
tubes is rarefied, the external orifices of the spiracula are forced open,
and the functions of life are again carried on.

This fact is not to be doubted, since we see the same thing take
place in the vermes, when they shut up for the winter. The garden-
snail,
as soon as the cold weather sets in, fixes itself upon any hard
substances, by throwing out a slime which cements the open edge of
the shell to the surface, and the snail remains there during the win-
ter-months; all the organs of the body being in a state of rest.

When warmth and moisture are applied, the membranous film
falls off; a globule of air that remained in the cavity of the lungs be-
comes rarefied, and forces its way out, and admits of fresh air being
applied to these organs.

In animals in which the circulation of the blood is carried on by
means of a heart, the blood is aerated in very different propor-
tions.

The aphrodite aculeata has, properly speaking, no blood-vessels;
the water is received by thirty-two lateral openings between the feet,
into the cavity under the muscles of the back, and there applied to
the surfaces of the projecting cells, of which there are two rows, fif-
teen in each; through these the air in the water is communicated to
the coeca contained in them, which Sir E. Home considered to be the
respiratory organs.

In the leech there is no heart, but a large vessel upon each side of
the animal; and the water is received through openings into the
belly, into the cells or respiratory organs, and passes out through the
same.

In the earth-worm there is an artery that passes up the back, and a
corresponding vein passing down from the head upon the middle of
the belly; near the head, there are five pair of lateral canals that
swell out beyond the size of the large vein, so that they become re-
servoirs of blood to supply the vessels of the head, when wanted to
bore through the earth, and the action of the muscles so employed
will, by their situation, accelerate the circulation. The oesophagus,
lying in the center of these reservoirs, will, by the action of its coats
while the animal is eating, have an influence on the circulation.
The blood is aerated by lateral cells in the same manner as in the
leech.

In the muscle, the gut passes through the heart, which is an oval
bag, having no auricle, unless the two large veins are called such; the
[Seite 167] coats of the ventricle are very thin, but the action of the intestine
makes up for this deficiency.

In the earth-worm, the circulation is properly in a circle without
beginning or ending. One vessel runs upwards to the head, along
the back, communicating with the lateral reservoirs, but still a conti-
nued tube goes on. It is the same with the vein or opposite vessel
that runs down the tail, and the branches that go from the artery to
the lateral cells, have corresponding branches returning the blood to
the great vein. This may be considered as one mode of circulation
peculiar to this tribe; and it is admirably contrived that the blood
may be accelerated in its motion by the muscular action of the body
of the animal, without any increase of action in the arterial sys-
tem.

The aeration of the blood in this mode of circulation is imperfect,
only one portion being aerated and mixed with the rest, in which no
such changes have been produced.

In the lumbricus marinus, although the principle of the circulation is
the same, there are many strongly marked differences in the mode
of carrying it into effect.,

There is, as in the terrestris, one trunk behind, going from the tail to
the head, and one from the head to the tail on the belly, completing the
circle; but in this animal there are external gills, which remain pro-
truded while the animal is in the water, and the blood has such a ve-
locity in these vessels, that they may be considered as so many small
ventricles; this is an approach to the construction of the gills of the
sepia. In this circulation there are two regularly formed auricles,
supplied by lateral veins from the viscera attached to the sides of the
great artery, so as to increase the supply of the blood, and afford
quantity as well as velocity; while it gives off branches to the gills,
the main trunk pursues its course, supplying the body. In this ani-
mal, it is only a portion of the blood which is aerated, and from the
structure of the gills that must be in a much greater degree than in
the lumbricus terrestris.

The animal whose heart is nearest in structure to those described
is the oyster, in which the whole blood is aerated in passing through
the gills, before it is received into the auricle. In this animal, the
auricle and ventricle are very thin in their coats, so much so as to
make them unequal to apply force to the blood; but the ventricle is
laterally connected to the great muscle, whose action will accelerate
the circulation.

In the toredo navalis the heart is situated upon the back of the ani-
mal near the head, consisting of two auricles of a thin, dark coloured
membrane; the auricles open by contracted valvular orifices into
two white stony tubes; those united form the ventricle which termi-
nates in an artery that goes to the bony shell. The heart is loosely
attached; its action is distinctly seen through the external covering
and in some instances continues to act after it is laid bare.

The first contraction is in the two auricles, which are shortened in
[Seite 168] that action, this enlarges the ventricle before it contracts. The great
artery from the ventricle goes directly to the head, and the vessels
that supply the auricles are seen to come from the gills. The auri-
cles are lined with a black pigment, so that their contents cannot be
seen through their coats; and the ventricle from its thickness is not
transparent, but the muscles of the boring shells are of a bright red,
and all the parts between the heart and head are supplied with red
blood.

The structure of the heart is different from that of the lumbricus
marinus,
and consequently the circulation is by no means peculiar.

This animal’s heart may be said to be the first in this series that is
complete, and this first regular circulation of the blood, every part of
which passes through the vessels of the gills, and even through the ca-
vities of the heart. As this animal is to work a machine capable of boring
a very hard substance, and to go on working during the whole of that
period of life in which its growth is continued, to make room for the
increased bulk, so it requires that the blood be more highly aerated
and supplied with greater velocity to these active organs. The heart
also, to give it greater advantage in these respects, is placed near to
the boring shells, so that the blood which goes to them, is of the
brightest colours.

In this circulation the first action of the heart is to supply the dif-
ferent parts of the body with aerated blood; upon this the activity of
the heart is wholly exerted; the blood is returned more slowly
through the gills, and remains there a longer time, so as to receive a
greater degree of the influence from the air contained in the water.

This is the principle on which the circulation of many of the
vermes is established, and is exactly the reverse of what takes place in
fishes, reptiles, and the higher orders of animals.

The mode in which the breathing organs of the toredines are sup-
plied with water, makes it evident that all sea-worms which have no
cavity for the reception of sea-water, must have the breathing organs
placed externally, as is the case with all those species of actinia met
with in the West Indies, called animal flowers, and the beautiful mem-
branous expansions they display, resembling the petals of flowers,
are in fact the breathing organs acting at the same time as tenta-
cula.

In the sepia this mode of circulation is rendered more complex,
but the same principle is adhered to. In the toredines the water is in-
timately applied to the gills from the simplicity of their structure; but
in the sepia they are more complex, and require force to apply the
water to every part of them, and for this purpose there is a bulb and
double valve placed at the roof of each gill.

In the sepia the blood is brought to the gills from all parts of the
body by three sets of veins, all branching off from the trunk of the
vena cava., The common trunk that goes to each gill, is of so large
a size and so thin in its coats, that to prevent the regurgitation of the
blood, the valve is interposed; the blood having got into the gills,
[Seite 169] and having pervaded every part of the branchiae, it is conveyed by a
smaller trunk to the auricle, so that the gills will never be completely
emptied; it is then received into the ventricle, and carried into every
part of the body. The circulation is also similar in the lamprey, lam-
pores,
the myxene, and an animal nearly allied to it from the South
Seas, which has never received a specific name, although there are
peculiarities in the gills from which these animals must be considered
in their aeration inferior to fishes at large.

In the lamprey and lampern, the water is received by the seven la-
teral openings on each side of the animal into the bags that perform
the office of gills, and passes out by the same orifices, the form of the
cavities being such as to allow the water to go in at one side and out
at the other, after having passed over all the projecting parts. Some
of the water escapes into the middle tube, and from thence passes
out either into the other bags or at the upper end into the oesopha-
gus.

The muscular structure of the branchial artery of the dog-fish, and
the direction in which that artery leaves the ventricle, are exactly the
same as in the squalus maximus, only they are seen on so small a
scale, that they do not arrest our attention; but when magnified to
the same size which they acquire in this fish, they make a stronger
impression upon the mind, and force us irresistibly to inquire after
their use. The direction of the artery appears to be common to fishes
in general, but the muscular structure that is met with in the bran-
chial artery, is confined to particular tribes. Sir. E. Home met with
it in the sturgeon, and says it is common to sharks.

In the wolf-fish, the anarhichus lupus, the muscular structure of the
branchial artery is nearly the same, but the valves are placed close to
the opening of the ventricle, and only two in number. In the turbot
there is no muscular structure in this part, but the coats are extremely
elastic, and admit of being very considerably dilated, particularly at
its origin, where three valves are placed, and so contrived, that the
dilatation of the artery makes them shut more closely.

In the lophius piscatorius there is no appearance of muscularity in
the coats of the branchial artery, and no lateral valves, as in other
fishes; but there is a muscular tube half an inch long, rising from
the edge of the opening of the ventricle, which projects into the ar-
tery.

These different structures, so unlike one another, and bearing no
resemblance to the mechanism in the same parts in quadrupeds,
make it probable that the circulation through the gills is impeded by
the external pressure of the water in different degrees according to
the depth of the fish from the surface; therefore in those fishes
which frequent the great depths, as the squalus, in all its tribes, there
is a muscular structure in the coats of the branchial artery, which,
when the fish is deep in the water, by its contraction diminishes the
area of the vessel, and makes the valves perform their office; but
when the fish is near the surface, this muscular structure, by its re-
[Seite 170] laxation, lenders the area of the artery so wide, that regurgitation of
the blood takes place into the ventricles, and prevents the small ves-
sels of the gills from being too much loaded.

That such regurgitation can take place when the muscle is relaxed,
is ascertained by the ventricle being readily injected after death with
coarse injection from the artery, the valves allowing it to pass.

In fishes that swim deep and do not come to the surface, as the
wolf-fish, the regurgitation does not take place into the ventricle;
but the relaxation of this muscular portion of the artery allows it to
dilate and form a reservoir, and the valves remain closed so as to
prevent more blood leaving the ventricle.

In fishes residing at moderate depths, as the turbot, elasticity is
employed as a substitute for muscular powers, there being less varia-
tion. In the lophius piscatorius, which probably never descends
into water of great depth, the ventricle is so weak that the supply of
blood to the gills is regulated by the contraction and relaxation of a
muscular valve.

The heart of the manatee, or dugong of the West Indies, has its
ventricles completely detached from each other: when we compare
this with the heart of the whale tribe, we find that the right ventricle
in the whale is a nearer approach to the left than in the quadruped.

The ventricles in the dugong, although similar in structure, are not
exactly of the same size. The left is thickest, and half an inch
longer.

The auricles resemble those of the whale, having the same trans-
verse ligamentous bands.

The valves had nothing particular in their appearance.

The foramen ovale was entirely closed, but its situation was dis-
tinctly seen.

The relative size of the aorta and pulmonary artery was the same
as in the elephant.

CHAPTER XIII.
OF THE ABSORBING VESSELS.

[Seite 171]

§ 170. 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 con-
verse of this proposition 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-blooded animals.

In many of what are called white-blooded animals, there is
a kind of absorption very evident; as in the armed polypes,
whose parenchyma becomes tinged in a short time with the
colour of those insects which have been swallowed. The ex-
istence of absorption is inferred by analogy from other pheno-
mena, as the metamorphosis of larvae, &c. But no true
system of real absorbing vessels has been hitherto demon-
strated in these animals.*

§ 171. This system (which comes most properly under con-
sideration in the present chapter, on account of its relation to
the circulation of the blood) consists of the lacteal vessels,
which arise from the small intestines, and of the proper lym-
phatic
vessels, which belong to the rest of the body. It in-
cludes 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 vessels; and lastly, the thoracic duct,
[Seite 172] which is the chief canal for conveying the fluids from the
lymphatic system into the blood.

The structure and offices of the absorbent glands have been illus-
trated by the observations of Mr. Abernethy on the formation of
these parts in the whale. He found the mesenteric glands of that
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 lymphatics have any
communication with the venous system prior to the termination of
the thoracic duct. The observations of that ingenious veterinary
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.

The communication of the lymphatics with the veins in the four
classes of vertebrated animals has of late years been demonstrated by
Lippi, Fohmann, and Lauth, and in the anatomical museum of Heidel-
berg there are numerous beautiful specimens shewing this fact.

mammalia.

§ 172. All the parts of the absorbing system, which have
been just enumerated, are most perfect and manifest in this
class of animals: it is well known indeed that all the chief
parts of this important system of vessels have been first disco-
vered in mammalia. When their lacteals contain chyle, they
are distinguished by their white colour from the other absorb-
ing vessels, the contents of which are either limpid, or of a
slight yellow tinge. The former vessels run together in con-
siderable trunks, particularly in the sheep and goat: the lat-
ter, or true lymphatics, may be seen to advantage on the hind-
leg of the horse, where they follow a tortuous course.

The thoracic duct is double in some quadrupeds,* as in the
dog, and forms at its commencement, more constantly than in
the human subject, a vesicular enlargement, called the cisterna,
[Seite 173] or receptaculum chyli. The course and distribution of the
thoracic duct vary in quadrupeds, at least in our domestic
animals, as much as in the human subject. It forms, not un-
frequently, in the dog a kind of annular portion at its upper,
or more properly anterior end; which trivial variety Van Bils
transformed into a constant and important circumstance, and
called ‘“receptaculum tortuosum.”’*

In many mammalia, particularly of the order ferae, the me-
senteric glands are collected into one mass, which is known by
the inappropriate name of pancreas Asellii.

Sir Everard Home has found that in the sea-otter the receptaculum
chyli sends two trunks to form the thoracic duct. These have fre-
quent communications; so that there are sometimes three, frequently
four, and never fewer than two trunks running parallel to each other.
Philos. Trans. 1796, pt. 2.

birds.

§ 173. 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 conglobate glands are found in other parts in several
of the larger birds. Their thoracic duct is double.

In a communication made to the Academy of Medicine at Paris in
1819, M. Magendie denied the existence of lymphatics, with few ex-
ceptions, in the class of birds. He dissected more than fifty birds of
different kinds, and was not enabled to discover the lymphatics in any
part of the body except in the neck of the swan and goose; in this
part he found the lymphatics and glands as in mammalia, filled with a
diaphanous and colourless lymph. The opinion of Magendie has been
satisfactorily refuted by several anatomists, particularly by Dr. Lauth
of Strasburg, who, in an excellent treatise, entitled Mémoire sur les
vaisseaux Lymphatiques des Oiseaux et sur la manière de les preparer,

has proved the existence of lymphatics in birds.§

amphibia.

[Seite 174]

§ 174. Lacteals are found in great number in the delicate
mesentery of the turtle. The thoracic duct is double. There
seem to be no lymphatic glands at all.*

The distribution of the lymphatics on the intestine of the turtle
forms one of the most elegant preparations in comparative anatomy.
By fixing the injecting tube in a vessel near the intestine, and wait-
ing with a little patience, the quicksilver will gradually find its way
into the minute ramifications 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, co-
vering the whole internal surface of the intestine so completely that
the point of a pin could scarcely be placed between them.

fishes.

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

CHAPTER XIV.
ON THE ORGANS OF RESPIRATION.

[Seite 175]

§ 176.* The incessant continuation of the great chemical pro-
cess by which oxygen, the true pabulum vitae, is exchanged
for hydrogen and carbon, is essentially necessary to the well-
being of the greater part of animals. Yet the organs and
mechanism by which this wonderful function is carried on
vary very considerably. In the mammalia after birth; in
birds, when they have left the egg; and in amphibia 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.

mammalia.

§ 177. The lungs of quadrupeds agree on the whole in
structure, form, and connexion, with those of the human sub-
ject. In the cetacea, on the contrary, and in the web-footed
[Seite 176] 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 appearance. They are adherent to the pleura, as
well as to the very strong and muscular diaphragm.*

birds.

§ 178. The respiratory organs of this class constitute one
of the most singular structures in the animal economy, on ac-
count of several peculiarities which they possess; but more
particularly in consequence of their connexion with the nu-
merous air-cells which are expanded over the whole body.

The lungs themselves are comparatively small, flattened, and
adherent 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 thorax, as well as the ab-
domen, is occupied by the membranous air-cells, into which
the lungs open by considerable apertures. Those of the tho-
rax are divided, at least in the larger birds, by membranous
transverse septa into smaller portions,§ each of which, as well
as the abdominal cells, has a particular opening of communica-
tion with the air-cells of the lungs, and consequently with the
trachea. The membranes of these cells in the larger birds are
provided here and there with considerable fasciculi of muscu-
lar fibres, which have been regarded as a substitute for the
diaphragm, which is wanting in this class of animals.ǁ They
[Seite 177] also serve very principally, as we may ascertain by examining
large birds in a living state,* to drive back again into the
lungs the air which they received in inspiration, whence the
repletion and depletion of the thoracic cells must alternate
with those of the abdominal cavities.

The cartilaginous annuli of the trachea, which are in general more
complete in the other 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 viscus. In the
ostrich this aperture is surrounded by circular muscular fibres, a
peculiarity which does not seem to have been hitherto noticed.

§ 179. Besides 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 multan-
gular bones of the trunk, as the sternum, ossa innominata,
dorsal vertebrae, &c. All these are destitute of marrow in
the adult bird, at least in their middle; so that the cylindrical
bones form large tubes, which are only interrupted towards
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 apertures§ (most
easily shown in those extremities of the cylindrical bones
[Seite 178] which are turned towards the sternum) communicating with
the lungs by small air-cells; which facts may be shewn by va-
rious experiments on living and dead birds.*

These receptacles of air probably serve the purpose of
lightening the body of the bird in order to facilitate its mo-
tions. This effect is produced in most birds to assist their
flight; 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, 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 connected 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.

§ 180. 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
anatomists have supposed, with the organ of smelling, but
forms a part of the air-cells.

§ 181. Besides the uses which have been already pointed
out, these receptacles of air diminish the necessity of breath-
ing frequently in the rapid and long continued motions of se-
[Seite 179] veral birds, and in the great vocal exertions of the singing
birds.* They are also obviously serviceable in the evacuation
of the faeces, and probably assist in the expulsion of the egg.

The bones of birds, in so far as their air-cells are concerned, form
two distinct systems, the one being filled with air through the trachea
and lungs, the other immediately from the mouth or nose. To the
latter the bones of the head, to the former those of the trunk, of the
neck and extremities belong. With very little practice one may tell,
in a bone fully developed, whether it contains air-cells or not, from
the mere external appearance, without at all seeing the opening
through which the air enters. Such bones, in addition to their being
devoid of marrow, are generally of a clearer white colour than those
filled with marrow. Frequently the external walls of the air-bones
are so thin that their internal cells can be very well seen. Neverthe-
less, mere external appearances may deceive, and in order to pre-
vent this the openings leading to the air-cells should be sought for-
These openings are in general, as their connexion with the lungs or
air-tubes renders necessary, situated in concealed parts, and the ex-
tremities of bones. This circumstance, coupled with their smallness,
makes their discovery so difficult, that in many cases not only the
cleaning of the skeleton and the separation of the bones from all their
connexions, but also the minutest examination of their surface, are
necessary to discover their existence. In long bones the openings to
the air-cells is generally situated close to either extremity. In bones
which exist in pairs there is commonly only one, or where several
exist they are so close together as to be nearly united. The direction
in which the openings penetrate the bony parietes is not uniform.
Sometimes it is oblique, so that a short oblique canal is formed; at
others there is an oblique groove with a sieve-like base for the entrance
of the air. The edges of the openings are even, smooth, and rounded,
which gives them a peculiarly regular appearance. Their shape is
either circular, oval, or elliptical. Their breadth bears some kind
of proportion to the size of the bone, or at least to the extent of
the internal cells, so that large birds, and large bones, have much
larger openings than the small ones. There are, however, very re-
markable exceptions. With respect to the internal air-cells great
differences exist. There has been found in the internal periosteum
which lines the air-cells, in the bones of the upper and lower extre-
mities, a fine net-work of blood-vessels. It is known that the air-
bones in young birds are filled with marrow, which becomes gradu-
ally absorbed to make room for the admission of air. This gradual
expansion of the air-cells, and absorption of the marrow, can no
where be observed so well as in young tame geese when killed at dif-
[Seite 180] ferent periods of the autumn and winter. The limits to the air-cells
may be clearly seen from without by the transparency of the bony
parietes. From week to week the air-cells increase in size, till to-
wards the close of the season the air-bones become transparent. In
all these bones the marrow first disappears from the vicinity of the
opening which admits the air, and continues longest at the points
further removed from this opening. Towards the close of the sum-
mer and beginning of autumn, although in external appearance the
young goose resembles the parent, no trace of air-cells can be disco-
vered in its bones, the interior of the bones being then filled with
marrow. About the fifth or sixth month the marrow begins to dis-
appear. This circumstance, which applies also to other birds, shows
with what caution one should form an opinion, from young birds only,
on the size of the air-cells. In many kinds of birds the air-cells of
some bones are never fully developed, although they have the open-
ings in the bones which lead to the air-cells. The obvious use of this
construction in the bones of birds, appears to be that of lessening the
weight of the bone as compared with its size, without at the same
time diminishing their necessary peripherical extent. Whether birds
possess the power of voluntarily letting out the air so as to render
them specifically lighter, or whether they contain lighter gases in
them, has not been ascertained. Vid. Nitzsch’s Osteograf. Beitrage,
p. 3.

‘“In the eagle, hawk, stork, lark, and other high flying birds, these
cells are very large; and in many of those birds there are still larger
cells, ascending under the integuments of the neck, and passing be-
neath the skin of the inside of the arm and back of the shoulder. In
the stork we find 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.

amphibia.

§ 182. The lungs of amphibia* are distinguished from
those of warm-blooded animals, both by a great superiority in
point of size, as well as by a greater looseness of texture; which
circumstances are serviceable in swimming in many of these
animals.

It is well known that the lungs of turtles and frogs do not
collapse on opening the animals, like those of mammalia, but
often remain expanded, at least partially, for some time. Mal-
[Seite 181] pighi, and lately Townson,* have explained this phenomenon
by the action of the constrictor muscles of the glottis. Bre-
mond thought this insufficient according to his experiments,
and ascribed much effect to the peculiar vitality of the lungs.

The amphibia are distinguished in all instances 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 characterizes all the viscera 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 an-
nuli of the bronchi terminate before these vessels enter the lungs.

§ 183. There are numerous projecting processes in the
lungs of the chameleon and newt; in the latter animal they
terminate behind in an elongated bladder. The serpents, at
least for the most part, have only a single lung, which forms
an elongated vesicular bag. In a coluber of four feet and a
half long, the lung measured one foot one inch; its anterior
half resembled a muscular intestine in appearance, and had an
elegantly reticulated internal surface, which resembled on a
small scale the inner surface of the second stomach of the
ruminating animals. The posterior part formed merely a
simple and long cavity with thin sides.

§ 184. In the tadpole, and the young of such lizards as
bring forth in water, there are two organs, which somewhat
resemble the gills of a fish (appendices fimbriatae, Swammer-
dam).§ It has been doubted whether the young of the true
[Seite 182] salamander are provided with these appendices; and Latreille,
in his Histoire Naturelle des Salamandres de France, p. 19,
and seq. has the following question, ‘“Les jeunes salamandres
terrestres ont elles des branches? voila une question que je
mets encore au rang des problemes.
”’ I answered this question
in the affirmative forty-one years ago; having observed that
the young of some pregnant salamanders, whom I kept in my
room in glasses, and who brought forth under my inspection,
had considerable branchial appendices.* These appendices
are connected to the sides of the neck, and hang loose from
the animal; they are not permanent, but are gradually with-
drawn into the chest, (within a few days, in the reptiles of
this country (Germany), where their remains may still be per-
ceived for some time near to the true lungs. That doubtful
animal, the siren lacertina from Carolina, has, according to
Hunter’s dissection, two bladder-like lungs, besides the exter-
nal branchiae.

The same circumstance holds good respecting that no less
mysterious creature, the proteus anguinus, from the Cirknitz
or Sitticher lake of Carniola; whose remarkable internal struc-
ture has been described and delineated by Dr. Schreibers in
the Philos. Trans. for 1801;§ and more recently by Signors
Configliachi and Rusconi in their elaborate monograph on the
proteus anguinus.

Instead of the branchial opening by which fishes again dis-
charge the water, which they have taken in at the mouth,
[Seite 183] some tadpoles have for this purpose a canal on the left side of
the head near the eye,* which must be distinguished from the
small tube on the lower lip, by which they attach themselves
to aquatic plants.

After an elaborate anatomical description of the proteus anguinus,
Signors Configliachi and Rusconi proceed to inquire whether it be
true, as many naturalists have believed, that this reptile breathes
with its branchiae and lungs at the same time, and, secondly, whether
the sirena lacertina is to be considered by zoologists as a larva, or as
a perfect animal. In respect to the bony apparatus of the branchiae,
they found a remarkable difference between the proteus, the sirena,
and the larvae of salamanders and frogs, both as to form and hardness.
In the siren and larvae there are four branchial arches on each side,
which are furnished with several projections on the surface; in the
proteus there are but three arches, which are perfectly smooth; those
of the proteus are osseous, while those of the siren and larvae are cartila-
ginous. These differences did not escape M. Cuvier, who in speaking
of the proteus, observes, that the bony apparatus of the branchiae is
much harder than it is in the sirena and the axolotl. Signors Con-
figliachi and Rusconi observed in the larvae of frogs, that when their
spine is nearly hardened into bone, and their metamorphosis is
beginning to be accomplished, the branchial arches become softened,
and ready to be absorbed. They observed the same thing in the
larvae of salamanders, with this difference, that the ossification of
the spine takes place in the latter much sooner than the period
of their metamorphosis; and when that period arrives, the portion of
their branchial apparatus, which remains to be converted into the os
hyoides, instead of softening, becomes hardened into bone. Thus
their observations fully confirm the conjecture of M. Cuvier, who, in
his description of the axolotl, has observed, that the apparatus sup-
porting the branchiae has a great resemblance to that of the sirena,
and that probably, at the period of its metamorphosis, a portion
remains to form the os hyoides of the salamander. Now, if the
branchial arches of the sirena, dissected by M. Cuvier, were entirely
cartilaginous, although the cranium, the lower jaw, and the vertebrae,
were already perfectly ossified, and if these are similar, in form and
number to those of the axolotl, which, in the opinion of M. Cuvier
himself, is a larva, and if, moreover, the branchial arches of the
proteus, which is a perfect animal, are osseous, and different in
all respects from those of the larvae hitherto known, do not all these
facts furnish us with a strong argument to prove that the sirena
[Seite 184] lacertina
is a perfect animal, and therefore essentially different from
the proteus? Signors Configliachi and Rusconi, after a minute exa-
mination of the organs of circulation and respiration in the proteus,
sirena,
and above mentioned larvae, conclude, that the proteus anguinus
is not an amphibious animal, with a double circulation, as many have
asserted, but a perfect reptile, entirely differing from all others,
inasmuch as it is a reptile in respect of its simple circulation, and a
fish in respect of its mode of breathing; in other words, it is a reptile
which in breathing inhales air mixed with water, whereas other rep-
tiles breathe atmospheric air; so that if we adopt the notion of a
chain of beings, the proteus anguinus would be the link uniting rep-
tiles with fishes. As the proteus is an animal which breathes only in
the water, and as its branchial circulation can be regarded only as a
minute part of its general circulation, it follows that it consumes
less oxygen than fishes. Hence the quantity of blood which is de-
carbonized in its branchiae, within a given space of time, must be
much less than that which, under similar circumstances, is decarbo-
nized by fishes. This accounts for its inertness, its slow growth, its
power of fasting longer than any other animal of its class, the fluidity
of its blood, and its capability of living in stagnant water, where a
fish of its size would die.

fishes.

§ 185. 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 moveable gill-cover, (operculum bran-
chiale
) which is wanting 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 contain-
ed in the water;* as those animals which breathe, derive it
immediately from the atmosphere. They afterwards discharge
the water through the branchial openings (aperturae bran-
chiales
); 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.

§ 186. We have already shewn 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 arte-
rial state. The distribution of these vessels on the folds and
[Seite 185] divisions of the gills constitutes one of the most delicate and
minute pieces of structure in the animal economy.*

Each of the gills consists, in most fishes, of four divisions,
resting on the same number of arched portions of bone or car-
tilage, 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 se-
veral openings.

§ 187. Many animals of this order possess a single or dou-
ble swimming bladder, which in the fresh-water fishes of this
country, (Germany) contains azotic gas; and in salt-water
fishes, chiefly carbonic acid gas. It has not been hitherto de-
termined, whether it be subservient 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 cesophagus, and
sometimes with the stomach, by a canal (ductus pneumaticus)
containing, in some instances, as the carp, valves which seem to
allow the passage of air from the bladder, but not to admit its
entrance from without.

The air-bladder does not exist in many fishes; whence Cuvier ar-
gues with justice against the opinion which assigns this part an im-
portant office in respiration. Indeed it seems much more probable
[Seite 186] that it is subservient to the motions of the animal. For it is lar-
gest in such fishes as swim with considerable velocity. It is want-
ing in the flat fishes; where the large lateral fins supply its place, and
in the shark, where its absence is compensated 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 mackarel (scomber scombrus). Its form is infinitely varied in the
different genera and species. Its cavity is generally uniform; 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 ves-
sels, which contain air. These unite together, and open into the ca-
vity.

insects.

§ 188. That white-blooded animals indispensably 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 point:
experiment has actually proved the exchange of carbon for
oxygen.*

White-blooded animals are moreover distinguished 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.

§ 189. Many aquatic insects, as the genus cancer, have a
species of gills near the attachment of their legs. The others,
[Seite 187] and particularly the land-insects, which constitute, as is well
known, by far the greatest number of this class of animals, are
furnished with air-vessels or tracheae, which ramify over most of
their body.* These tracheae are much larger and more numer-
ous in the larva state of such insects as undergo a metamor-
phosis (in which state also the process of nutrition is carried
on to the greatest extent) than after the last, or, as it is called,
the perfect change has taken place.

In this class of animals the scorpions, being also provided
with fins, present an extraordinary instance of an animal,
which, though living nearly in the air, breathes like fishes.
§ 190. A large air-tube (trachea) lies under the skin on each
side of the body of larvae, and opens externally by nine aper-
tures (stigmata): it produces on the inside the same number of
trunks of air-vessels, (branchiae) which are distributed over the
body in innumerable ramifications.

Both the tracheae and branchiae are of a shining silvery co-
lour; and their principal membrane consists of spiral fibres.
The most numerous and minute ramifications are distributed on
the alimentary canal; particularly on the above-mentioned
corpus adiposum.

§ 191. There is a great variety in the number and situa-
tion of the external openings by which insects receive their
air.§

[Seite 188]

In most instances the stigmata are placed on both sides of
the body. The atmospheric air enters by 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 several animals of this class during their metamorphosis.
Thus in the larva of the common gnat, (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
head.*

vermes.

§ 192. In this class, which comprehends such very different
animals, the structure of the respiratory organs is proportion-
ally various. 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.

§ 193. Those vermes, however, which are furnished with
proper organs of respiration, have the same variety in their
structure which was remarked in insects. Some, as the cuttle-
fish,
oyster,§ &c. have a species of gills, varying in structure
in different instances. But the greatest number have air-ves-
sels or tracheae.ǁ Several of the testaceous vermes have both
[Seite 189] kinds of respiratory organs. In some of the inhabitants of bi-
valve shells, as the genus Venus,* the air-vessels lie between
the membranes of a simple or double tubular canal, found at
the anterior part of the animal, and capable of voluntary ex-
tension 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.

In the terrestrial gasteropodous mollusca, of which we may in-
stance 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 190]

§ 194. Aristotle has correctly observed, that those animals
only, which possess lungs, consequently 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 ant-
eater,
the manis, the cetacea, 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 quails*
and frogs in several parts of Siberia.

In a preparation – a dried one indeed – of the larynx and
lungs of the two-toed ant-eater, I find the larynx entirely bony,
that is, of the same substance with the os hyoides. The tra-
chea, which is extremely short, is a merely membranous canal,
without any perceptible trace of cartilaginous rings. J. Hunter
found no thyroid gland in the whales, which he dissected.
This coincides with the hypothesis upon which this gland is
supposed to be connected with the formation of the voice.

mammalia.

§ 195. Most animals of this class have the following cir-
[Seite 191] cumstances 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 liga-
menta glottidis (ligamenta thyreo-arytaenoidea); between which
on each side the ventriculi laryngis are situated. The epiglot-
tis does not exist in most of the bat kind; and in some mouse-
like animals, as the rell-mouse, (glis esculentus) it is hardly
discernible. The superior ligamenta glottidis, as well as the
ventriculi laryngis are wanting in some bisulca, as the ox and
sheep.

§ 196. Some species of mammalia have a peculiar and cha-
racteristic voice; or at least certain tones, which are formed
by additional organs. Thus there are certain tense mem-
branes in some animals; and in others peculiar cavities, open-
ing into the larynx, and sometimes appearing as continuations
of the ventriculi laryngis, which are destined to this purpose.

The neighing of the horse, for example, is effected by a de-
licate, and nearly falciform membrane, which is attached by
its middle to the thyroid cartilage, and has its extremities run-
ning along the external margins of the rima glottidis.*

The peculiar sound uttered by the ass is produced by
means of a similar membrane; under which there is an exca-
vation in the thyroid cartilage. There are moreover two large
membranous sacs opening into the larynx.

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 pecu-
liar vocal organs of the mother: a fact which, like many others,
[Seite 192] cannot be at all reconciled with the supposed pre-existence
of previously formed germs in the ovarium of the mother.

I have adduced this essential, and really specific difference
in the structure of the larynx of the horse and ass: as one of
the many arguments which overthrow the rule adopted by
Ray, Buffon, and others, of ascribing to one and the same spe-
cies all such animals as produce by copulation an offspring
capable of subsequent generation.*

The cat has two delicate membranes lying under the liga-
menta glottidis; which probably cause the purring noise pe-
culiar to these animals.

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

Several apes§ and baboons,ǁ as also the reindeer, have
on the front of the neck large single or double laryngeal sacs,
of various forms and divisions, communicating with the larynx
by one or two openings between the os hyoides and thyroid
cartilage.

In a common ape (simia sylvanus) I found the right laryn-
geal sac three inches long, and two inches in circumference;
while the left was not larger than a nutmeg. The larynx of
the simia cynomolgus may be seen in Camper’s account of that
animal.

Some of the cercopitheci, as the cercopithecus seniculus,
and Beelzebub, have the middle and anterior part of the os hy-
oides formed into a spherical bony cavity,** by which the ani-
[Seite 193] mals are enabled to produce those terrific and penetrating
tones, which can be heard at vast distances, and have gained
them the name of the howling apes.

The larynx of mammalia is generally of the same conformation as
in man. None of the large cartilages of the larynx are deficient, and
the opinion that some animals of this class want the epiglottis is
quite erroneous. In several, as the bat for instance, it is extremely
small. The size of the larynx is proportionate to the strength of the
sounds which the animals utter. The absolute size of the larynx
of the whale and the elephant is the largest, but relatively the la-
rynx of the lion has a still greater circumference. The cartilages
vary in their form; in the cercopitheci seniculi the os hyoides is di-
lated to a large bony pouch, and the thyroid cartilage at the same
time bent forwards, which explains the deafening noise which they
emit. In some animals, as the antelope gutturosa, there is a dilatation of
the thyroid cartilage, and in some there are fleshy appendices, or air-
sacs, which have their exit from the ventricles of Morgagni, or below
the epiglottis, and therefore are sometimes single and at other times
double. The apes of the old world have these sacs, and the orang-
outang
has them doubled; in others, as the green ape, they are sin-
gle; this is also the case in the reindeer. In reality the depressions
of the ventricles in the pig, or above the thyroid cartilage, as in the
horse and kangaroo, may be regarded as the incipient state of this
structure.

In most mammalia the number and situation of the vocal ligaments
are the same as in man. The trachea in long-necked animals, is natural-
ly much lengthened, and the number of rings increased; in men there
are from seventeen to twenty in number, whereas in the camel there are
seventy-four; in the stag, fifty-three; in the bullock, fifty-two; in the
domestic mouse, there are from fourteen to fifteen; in the hedgehog,
eighteen; in the rat, twenty-one; in the beaver, twenty-two; in the
cercopithecus seniculus, twenty-four; in the bear, twenty-eight; in the
hyaena, thirty-six; in the lion, cat, dog, and rabbit, thirty-eight; in
the hog, from thirty-eight to forty; in the lynx and guinea-pig, forty;
in the hare, forty-four; in the wolf otter, and sheep, fifty; in the roe,
sixty-three; in the ferret, sixty-seven; in the seal, seventy-eight. In
many animals, as in the cercopithecus seniculus, lion, and bear, the space
between the end of the rings is very great, so that the trachea can be
very considerably narrowed, which structure contributes to the inten-
sity of the sounds they are capable of emitting. In the hyaena the ex-
tremities of the rings of the trachea lap over each other, and are also
capable of being much compressed; a structure which probably oc-
casions the peculiar cry of that animal. In a few mammalia the tra-
cheal rings are closed: entirely so in the beaver, and in the upper part
of the trachea in the seal. The muscles and nerves of the larynx pre-
sent in mammalia little variation from those of the human subject, ex-
[Seite 194] cept that in many animals those of the epiglottis are fully developed,
whereas in man they are very indistinct. See Rudolphi’s Grund-
riss der Physiologie,
vol. ii. part 1, p. 380; to which excellent work we
are indebted for much of the additional matter inserted in this edition.

birds.

§ 197. The most striking peculiarity in the vocal organs of
this class, a peculiarity which belongs to all birds with a very
few exceptions, consists in their possessing, what is commonly
called, a double larynx, but which might be more properly de-
scribed as a larynx divided into two parts, placed at the up-
per and lower ends of the trachea. They have also two rimae
glottidis.

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

§ 199. The apparatus, which is chiefly concerned in form-
ing the voice of birds, is found in the inferior or bronchial la-
rynx. Hence the division of the trachea below the upper rima
glottidis scarcely produces any change in the voice of several
birds, as they can still utter sounds by means of the bronchial
larynx. This larynx contains a second rima glottidis, formed
by tense membranes; which may be compared in several cases,
particularly among the aquatic birds, to the reed pipes of an
organ. It is furnished externally 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 particularly the structure of the in-
[Seite 195] ferior larynx, vary very considerably* in the different species,
and even in 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 § 56). In the
spoonbill (platalea leucorodia) as also in the phasianus motmot,
and others, similar windings of the trachea are found, not in-
closed in the sternum. In many swimming birds the males
have at their inferior or bronchial larynx a bony cavity, the
form of which varies in different species, and which contri-
butes to strengthen their voice.

‘“A very little comparison of the mechanism of wind musical in-
struments with the organs of the voice in birds will shew how nearly
they are allied to each other; and it may be observed, that the sound
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 untu-
tored musician. The inferior glottis exactly corresponds to the reed,
and produces the tone, or simple sound. The superior larynx gives
it utterance, as the holes of the instrument; but the strength and
body of the note depend upon the extent and capacity of the tra-
chea, and the hardness and elasticity of its parts. The convolution
and bony cells of the windpipe, therefore, may be compared with the
turns of a French horn and the divisions of a bassoon; and they pro-
duce the proper effects of these parts in the voices of those birds in
which they are found.”’ Rees’s Cyclopaedia, art. Birds.

[Seite 196]

The larynx of birds is divided into an upper and lower, and the
lower forms the proper organ of voice. At the point where the
lowest bony ring of the trachea branches off to form the bronchia,
the skin folds on itself, and constitutes at the opening of each bron-
chus an elastic membrane, which projects into it, somewhat analogous
to the vocal ligaments in mammalia. In the parrot tribe this division
does not exist, and consequently there is not a double rima glottidis,
as in other birds provided with vocal organs. Cuvier could not find
this membrane in the vultur papa; and Rudolphi, who had an op-
portunity of examining this vulture, as well as the vultur aura, was
unable to discover it. Singing birds have five pairs of muscles, and
the parrots three, which are attached to the semi-circular rings of the
divisions of the trachea, and relax or tighten the rimae glottidis.
Birds which utter a single cry, as the accipitres and many aquatic
birds,
have only one such pair of muscles; other aquatic birds and the
gallinae have none. Cuvier has admirably proved in living birds that
this lower larynx is the proper organ of voice; he divided the tra-
chea above the lower larynx, and closed the upper part of it. The irri-
tated animal emitted by the lower larynx its accustomed sounds in a
weaker tone; the same sounds were emitted when he removed the
whole neck. The parts analogous to the cartilages of the larynx in
man are very small in birds, and in structure bear a greater resem-
blance to bone. In most birds they lie close behind the tongue and
the os hyoides, and form the commencement of the trachea. The
fissure which they form, and which is not protected by an epiglottis,
is opened by one pair of muscles, and closed by another. It merely
serves for the passage of the air, being the commencement of the
organ of respiration.

The trachea presents in many birds very remarkable differences.
In some gallinaceous birds it makes a great curve before the sternum,
as in the crax and penelope. In the urogallus (cock of the wood) this
curve takes place in the neck; in the crane and anas cygnus in the
keel of the sternum. In many aquatic birds as the anas clangula,
fusca,
&c. the trachea is considerably dilated in one or more places.

In general the great development of the vocal organs is peculiar to
the male; as, for instance, the curve external to the sternum, the
osseous bladders of the trachea, and of the lower larynx; the greater
curvatures in the keel of the sternum occur in both sexes; in males,
however, they are stronger.

amphibia.

§ 200. The structure of the vocal organs in this last class
of animals, which possess a voice, is on the whole very simple;
although it varies in several genera and species, and sometimes
in the two sexes.

§ 201. The tortoises (at least the testudo graeca) may be
[Seite 197] said to have two tracheae: for the short common trunk divides
at the third cervical vertebra into two long branches, which
descend far into the chest before they enter the lung. Each
of them makes a large lateral curvature, over which the two
aortae abdominales bend their course.* 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. Ligamenta glottidis
exist in all the animals of this class.

§ 202. The males of some frogs are distinguished by pecu-
liar air-bags. The tree-frog (rana arborea) has a large sac
in its throat; and the green frog (rana esculentd) has two
considerable pouches in the cheeks, which it inflates at the
time of copulation by two openings close to the rima glot-
tidis.

All amphibia have the opening of the larynx without an epiglottis,
and the cartilages which form the larynx are very analogous to those
of the upper larynx of birds. Frogs, and some of the lizards, possess
a structure similar to the vocal ligaments. In the rana pipa Rudol-
phi found a very curious structure: in the male the larynx was com-
posed of two laminae of bone, compressed from above downwards,
of about ten lines in length, seven and a half lines broad at the
base, and six and a half in the centre. In the female it was smaller,
and merely cartilaginous. The bronchi proceed from the larynx
directly backwards, being very short in the male, and long in the
female. In the gecko fimbriatus Tiedemann (Meckel’s Archiv. iv. s.
549) discovered in the trachea immediately below the larynx a dila-
tation half an inch long, and three lines broad, which he supposes to
be of service to the animal when under water; for it has been
asserted that this gecko lives several months in the year in fresh
water at Madagascar, though Rudolphi thinks this very improbable,
since its structure has not the remotest resemblance to that of an
aquatic animal. This learned naturalist considers it, from analogy
to birds, of use in strengthening the organs of voice, as in the pipa;
and this opinion is confirmed by the circumstance of another gecko
(the toc-kai of Siam) being distinguished for its discordant cry.
[Seite 198] A very shrill sound is uttered by frogs, especially the bull-frog
(rana ocellata). Whether the singing-bladders, as they are termed,
of the green frogs of Germany, assist them in uttering this sound,
as P. Camper thinks, (Kleine Schriften, vol. i. s. 141, 150) is still
a matter of great doubt; since these structures do not commu-
nicate with the larynx, but only with the mouth. According to
Humboldt, (Obs. zur Zoologie, vol. i. p. 11) young crocodiles utter a
sound similar to that of cats; but he never heard any cry proceed
from the old ones. Most lizards, all the testudines, and tailed tad-
poles
are dumb. This is also the case with serpents, since their
hissing cannot be called a true voice. (Rudolphi Grundriss der Phy-
siologie,
vol. ii. p. 387.)

One exception to the last observation of Rudolphi will suggest
itself to the reader; but it may be doubted whether, even before
the Fall, serpents were endowed with the gift of speech. Dr. Bur-
net, in his Archaeologiae Philosophicae, rejects the Mosaic account of
the dialogue between Eve and the serpent, not indeed as fabulous,
but as fictitious or parabolical; and the silence of the physio-
logist is excused, therefore, by the scepticism of the divine. Be-
stiam illam loqui posse,
says Dr. Burnet, aut quacumque voce prater
sibila nondum scimus. At quid de ea re scivisse Evam credemus?
Si pro muto animali habuisset, ipsa loquela terruisset foeminam, et
ab omni sermonis commercio pepulisset. Quod si loquax fuit, et ser-
mocinator ab initio serpens, perdiditque loquelam ob hoc facinus quod
pietatem fidemque Eva suis blanditiis corruperat, hoc genus poenae neuti-
quam tacuisset Moses; neque levius damnum de lambendo pulvere ipsius
loco substituisset. Praeterea vis unicum serpentum genus, vel omnes
bestias agri vocales fuisse in Paradiso; ut olim arbores in nemore
Dodonaeo? Si omnes, quid commisere caeterae ut usum linguae per-
derent? Si unicum serpentum genus hoc gaudebat privilegio; foedum
animal et ab humana specie alienissimum qui potuit mereri prae aliis
omnibus, sermonis gratiam et beneficium?
‘“We know not whether
the serpent had naturally the faculty of talking, or of producing
any sound, beyond the hissing noise which is all it can achieve in
these days. What shall we suppose Eve to have known about this
matter? If she considered it a dumb animal, the very circumstance
of its entering into conversation with her must have alarmed a timid
female, and deterred her from continuing so monstrous an inter-
course. But if the serpent talked at its creation, and lost the gift of
speech for its wickedness in corrupting Eve, Moses would not have
failed to mention this punishment, nor would he have substituted
in its place the lighter inconvenience of being condemned to lick the
dust. Again, will it be contended that the race of serpents alone,
or that all beasts had the gift of speech in Paradise, like the talking
trees in the grove of Dodona? If they all talked, what have the
rest done that they too should lose the gift of speech? If serpents
alone enjoyed this privilege, how shall we account for this distinc-
tion having been specially conferred upon an animal of such a nasty
description, and so utterly unlike the human species?”’

[Seite 199]

Dr. Burnet, while he admits with philosophical candour that the
whole of the Mosaic account of the creation might be regarded as fa-
bulous, if found in a profane writer, and while he exposes the ab-
surdities involved in a literal interpretation of the Jewish cosmogony
with an air of pleasantry which might be mistaken for ridicule in a
less pious inquirer, acknowledges at the same time the divine inspi-
ration of Moses, and expresses a laudable indignation at the impiety
of those who have treated the sacred narrative with disrespect.
Succensere non possum, says the divine, ex Patribus et auctoribus an-
tiquis illis, qui in symbola aut parabolas aut sermones populares haec
convertere studuerunt. Succenseo autem Celso, qui anilem fabulam,
μυθον τινα ὡς γραυσι διηγουμενον, hanc narrationem appellat. Ubi recte
monet, per modum responsi Origines, ὁτι μετα τροπολογιας ταυτα ειρηται.

‘“I cannot be displeased with those Fathers of the church, and other
ancient writers who have treated the Mosaic account of the creation
as a popular story or parable, but I am undoubtedly displeased with
Celsus, who has called it an old woman’s story, which imputation
Origen has satisfactorily answered by observing that these things are
to be understood tropically.”’ Dr. Burnet’s Archaeologiae Philosophicae,
lib. ii. cap. 7.

[Seite 200]

THE ANIMAL FUNCTIONS.

[Seite 201]

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

[Seite 202] [Seite 203]

§ 203. This class of functions which constitutes the leading
character of animals, and has derived its name from that cir-
cumstance, affords to our observation a more clear and mani-
fest gradation, from the most simple to the most compound
structure, than any others in the animal economy.*

§ 204. In some of the most simple animals of the class
vermes, particularly among the zoophytes, little or no distinc-
tion of similar parts or structures can be discerned; and we
are unable to recognize any thing as a particular nervous
system, or even as a part of such a system. The power of
sensation and voluntary motion, which these possess, as well
[Seite 204] as any other order or class of the animal kingdom, prove that
the nervous matter must be uniformly spread throughout their
homogeneous substance. The almost transparent polypes,
(hydrae) which are often found in this country, (Germany) 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 power, of nothing but
a granular structure, (something similar to boiled sago) con-
nected into a definite form by a gelatinous substance.

§ 205. In many other vermes, and in insects, a ganglionic
system of 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 lat-
ter 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 exceeded in both these
points by the human subject, which, according to the inge-
nious observation of the learned Sömmering,* possesses by
far the largest brain in proportion to the size of the nerves
which arise from it.

The small size of the brain in proportion to the rest of the
nervous system has a very considerable influence on the whole
animal economy of cold-blooded, when viewed in comparison
with warm-blooded animals. It explains the diminished sym-
pathy between the two parts; and the consequently weak powers
of motion in their whole machine. It enables us also to under-
stand the remarkable independence of the vitality of their
parts upon that of the brain, and their possession of consider-
able individual powers of life, as also the extraordinary extent
of their reproductive powers.

[Seite 205]

The vast superiority of man over all other animals in the faculties
of the mind, which may be truly considered as a generic distinction
of the human subject, led physiologists at a very early period to seek
for some corresponding difference in the brains of man and animals.
They naturally investigated 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 comparison 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
physiologists, however, in following up this comparative view in a
greater number of animals, discovered several 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, Sömmering has furnished
us with another point of comparison, that has hitherto held 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 impressions, and is therefore devoted to the purposes of animal
existence. The second division will include 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 organ 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 excels all other animals that have hitherto
been investigated.

The brain of man is much larger than that of the simiae, when
compared with the size of the nerves which proceed from it; this
may be readily seen by looking at the comparative breadth of the
cerebral nerves and brain in man and different animals. The size of
the brain, as compared with that of the medulla spinalis in man, is
larger than in simiae, as may be perceived on comparing the trans-
verse diameter of the spinal marrow below the corpora pyramidalia
with the whole breadth of the cerebrum. The size of the brain in
simiae and the seal is larger in proportion than in other animals.
The classes of animals whose cerebrum is next in size, are the
lemures, cetacea, ruminantia, multungula, solidungula, ferae, et bradypoda.
The cerebrum is smallest in the glires, marsupialia, edentata, and
chiroptera. The cerebellum of simiae presents but few differences
from that in man. In one species, saimiri, it is greater than in
[Seite 206] man; and in a number of instances the ratio is the same or nearly
the same; for example, in the ox it is the same; in the cat, various
monkeys, and in the horse, it is nearly the same. (Vid. Warren
on the Sensorial and Nervous Systems, &c. p. 81.)

The researches of Sömmering on animals in 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 doci-
lity of the animal, to the rank which it would hold in a comparative
scale of mental powers.

The largest brain which Sömmering has found in a horse, weighed
1 lb. 4 oz.; and the smallest which he has seen in an adult man, was
2 lb. 5 1/2 oz. Yet the nerves arising from the former brain were at
least ten times larger than those of the latter.

The following table exhibits the proportions of the mass of the
brain to that of the whole body in man and the different classes of
animals. It will be observed that, caeteris paribus, small animals have
a larger brain, in proportion to their size, than larger ones: that the
brain of man is exceeded, in proportional size, by some few animals,
as mice, the smaller birds, &c.; that among the mammalia, the roden-
tia
have generally the largest, and the pachydermata the smallest
brain; and that the brain is extremely small in cold-blooded, as com-
pared with warm-blooded animals.

mammalia.

It forms in man from 1/22, 1/25, 1/30, 1/35, of the body, according to the
different periods of his life.

Orang-outangs.

In the Gibbon 1/48 of the body.

Sapajous (American Apes),

Saïmiri 1/22
Saï 1/25
Ouïstiti 1/28
Coaïta 1/41

African and Indian Apes.

Malbrouk 1/24
Callitriche and Patras 1/41
The monk ape 1/44
Mangabey 1/48
[Seite 207]

Magots and Macakos.

Macako (simia silenus) 1/96 of the body.
Magot 1/105
Papio 1/104

Makis.

Mococo 1/61
Vari 1/84

Cheiroptera.

Bat 1/96

Plantigrada.

Mole 1/36
Bear 1/265
Hedgehog 1/168

Carnivora.

Dog 1/47, 1/50, 1/157, 1/154, 1/161, 1/305
Fox 1/205
Wolf 1/230
Cat 1/82, 1/94, 1/156
Ounce 1/247
Pine-martin 1/365
Ferret 1/138

Rodentia.

Beaver 1/290
Hare 1/228
Rabbit 1/140, 1/152
Ondatra 1/124
Rat 1/76
Mouse 1/43
Field-rat 1/51

Pachydermata.

Elephant 1/500
[Seite 208]
Wild-boar 1/672 of the body.
Chinese hog 1/451

Ruminantia.

Stag 1/290
Roebuck 1/94
Sheep 1/351, 1/192
Ox 1/860
Calf 1/219

Solipeda.

Horse 1/400
Ass 1/254

Cetacea.

Dolphin 1/25, 1/36, 1/66, 1/102
Porpoise 1/93

birds.

Eagle 1/260
Sparrow 1/25
Chaffinch 1/27
Redbreast 1/32
Blackbird 1/68
Canary-bird 1/14
Cock 1/25
Duck 1/257
Goose 1/360

reptiles.

Tortoise 1/1140
Turtle 1/5688
Coluber natrix 1/792
Frog 1/172

fishes.

Shark 1/2496
Pike 1/1305
[Seite 209]
Carp 1/560
Dog-fish 1/1345
Tunny 1/13450
Silurus glanis 1/1887

The following table shews the proportion of the cerebrum to the
cerebellum in man and other mammalia. The rodentia have the
largest cerebellum in proportion to the cerebrum; and man has the
least cerebellum in proportion to the cerebrum of all the mammalia.

In man, the cerebellum is to the cerebrum 1 : 9
Saimiri 1 : 14
Saï 1 : 6
Magot 1 : 7
Papio 1 : 7
Monk Ape 1 : 8
Dog 1 : 8
Cat 1 : 6
Mole 1 : 4.5
Beaver 1 : 3
Rat 1 : 3.25
Mouse 1 : 2
Hare 1 : 6
Wild Boar 1 : 7
Ox 1 : 9
Sheep 1 : 5
Horse 1 : 7

The proportion of the cerebrum to the medulla oblongata is ascer-
tained by measuring their diameters. Sömmering and Ebel have
shewn that it is greater in man than in other animals, and that it fur-
nishes a good criterion of the degree of intelligence in the individual,
as it shews the relation which the organ of intelligence bears to the
organs of the external senses. There are, however, some exceptions
to this rule, as in the remarkable instance of the dolphin. The fol-
lowing table exhibits the proportions between the breadth of the me-
dulla oblongata at its base, and the greatest breadth of the cerebrum
in some of the mammalia, and in a few birds.

In man, the breadth of the cerebrum is to that of the
medulla oblongata, as

1 : 7
In the Ape 1 : 4
Macako 1 : 5
Dog 6 : 11 or 3 : 8
Cat 4 : 11
Rabbit 3 : 8 or 1 : 3
Pig 3 : 8
Ram 1 : 3
Stag 2 : 5
Roebuck 1 : 3
Ox 5 : 13
Calf 2 : 5
Horse 8 : 21
Dolphin 1 : 13

birds.

Falcon 13 : 34
Owl 14 : 35
Duck 10 : 27
Turkey 12 : 33
Sparrow 7 : 18

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, and the astonishing facility
with which the process is carried on, depend, if I mistake not, on the
great magnitude of their nerves, and the diminutive proportion of
their brain. The former parts are in consequence less dependent on
the latter; 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 vitality. Since, in consequence of
this latter endowment, 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 continued
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.”’ § 98.

mammalia.

§ 206. 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 con-
tained between their two laminae.

We have hitherto ascertained only one example of such a
formation of the falx, in the quadrupeds of this class; and this
I discovered in the ornithorhynchus, (Plate I. c.) an animal
[Seite 211] which abounds in instances of anomalous structure. Some-
thing similar is found in the cetacea, at least in the porpoise.
A similar structure, constituting an unique specimen of anato-
mical variety, is exhibited in the skull of a female, belonging
to my collection. The vitreous table of the frontal bone has a
long falciform bony crista, at the attachment of the falx. The
falx itself descends to various depths between the hemispheres
in the different species.*

A bony tentorium cerebelli is found in a great number of
mammalia; but its size and extent vary in the different spe-
cies. It is formed by peculiar osseous plates, extending from
the vitreous table of the parietal bones, and the petrous por-
tions 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 quadrangular 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) and others.

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 exem-
plified in the seal, dog, horse, the orycteropus capensis, and
didelphis wombat.

In the cranium of a young seal which I possess, the ante-
rior or upper surface of the tile-shaped piece is connected by
means of a strong perpendicular bony plate, extending to the
middle of the lambdoid suture, with the inner surface of the
occipital bone, where the falx terminates.

In some cases, as in the pig, the rabbit, some mice, &c., a
rudiment of the last mentioned lateral portions may be ob-
served; or at least the ridge of the petrous portion of the
temporal bone is much larger than usual. I have, in another
[Seite 212] place, described the chief varieties of the bony tentorium,
and have mentioned the uses possibly assigned to this struc-
ture.*

‘“It is difficult (says the author, in his Manual of Osteology) to
give a physiological explanation of the use of this bony tentorium.
The opinion which has been generally adopted by anatomists, 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 protect-
ing the cerebellum from the pressure of the cerebrum 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,
(copra ibex) in which I could not discover the least trace of such a
structure. Cheselden ascribes it to predacious animals only, (Anat.
of the Bones,
cap. 8) but I have already enumerated several others.
It may perhaps obviate the concussion 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 similar mechanical explanation has been
given of the falx and tentorium of the human subject; viz. that the
former protects the hemispheres from mutual pressure when the per-
son lies with his head resting on one side; and that the latter pro-
vides against the compression of the cerebellum by the superincum-
bent cerebrum. These explanations are assigned in the present day
by anatomists of such distinguished reputation as Sömmering and
Cuvier (De Corporis Humani Fabrica, vol. iv. p. 27. Leçons d’Anat.
compar.
tom. ii. p. 178). If the futility of this piece of physiology
were not sufficiently proved by considering that the cranium is accu-
rately filled, and that there is consequently no 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 ab-
sent, and the two hemispheres united throughout in one mass, with-
out any perceptible inconvenience during the patient’s life. (Transac-
tions of a Society for the Improvement of Medical and Chirurgical
Knowledge,
vol. ii. p. 212.) In four instances the anterior half of
the falx has been found 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 hemispheres adhered by
the pia mater covering their opposed plane surfaces; but were form-
ed naturally in other respects. A want of the falx has also been re-
corded by Garengeot (Splanchnologie, tom. ii. p. 24).

[Seite 213]

§ 207. The peculiarities which distinguish the brain of the
human subject from that of the mammalia,* consist chiefly in
the circumstance, which has been already noticed, of its pos-
sessing 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 spinalis.

The anatomy of the brain of cetaceous animals has not been so
minutely described as that of other classes of animals. In general, the
brain of the cetaceous tribe is small compared with the size of the
body. The brain of a common whale, nineteen feet in length, which
was examined by Scoresby, weighed about three pounds and three
quarters, although the weight of the animal was near 11,200 pounds.
Here the weight of the brain was about part of that of the
body, whilst that of the brain of an adult man is about four pounds,
and that of the body 140, the brain being the 1/35 part of the weight of
the whole body. Professor Tiedemann, of Heidelberg, has recently
published an account of the dissection of the brain of the dolphin.
(Treviranus’s and Tiedemann’s Zeitschrift fur Physiologie, vol. ii. p.
255.) The following are the results of this learned anatomist’s investi-
gations.

1. The cerebrum of the dolphin resembles that of the simiae, by its
size, and next to the cerebrum of the orang-outang, most resembles
that of man. Still in proportion to the size of the nerves, spinal
marrow, and cerebellum, it is of much smaller size than the human
cerebrum.

2. Each hemisphere of the cerebrum, as in man and simiae, consists
of three lobes, an anterior, middle, and posterior. The hemispheres
[Seite 214] are undoubtedly much smaller than those in man, since they do not
completely cover the cerebellum.

3. The breadth of the cerebrum of the dolphin exceeds its length,
which is scarcely the case with any other mammalia.

4. The convolutions of the cerebrum of the dolphin are more nu-
merous than in any other animal, even than in man.

5. The lateral ventricles consist in the dolphin, as in man and simiae,
of three horns, whilst in other mammalia the anterior and middle
cornua only exist.

6. The corpora albicantia, in the cerebrum of the dolphin, as of
most mammalia, are united into one mass. In man and the orang-
outang
they are perfectly distinct.

7. The fornix, septum lucidum, cornua ammonis, and corpora
striata, are in proportion to the size of the cerebrum of the dolphin,
and smaller than the same parts in man.

8. The corpora quadrigemina in the dolphin, as in other mammalia,
are much larger than these bodies in man.

9. The cerebellum of the dolphin is distinguished by its being
larger than in man; and its middle portion, as in seals and several
other animals, is not symmetrical.

10. The medulla oblongata of the dolphin possesses no trapezium.

11. The brain of the dolphin is particularly distinguished from that
of man and all other mammalia, by the absence of the olfactory nerves.
But on the whole the brain of the dolphin is developed in a greater de-
gree than in any other animal, if we except that of the orang-outang.

§ 208. Moreover, that remarkable and enigmatical collec-
tion of sandy matter, which is found in the pineal gland* of
the human brain, almost invariably after the first few years of
existence, has been hitherto observed in very few other mam-
malia, and those among the bisulca.

§ 209. In the proper quadrupeds (the quadrumana there-
fore being excepted) the anterior lobes of the brain form two
large processes, (processus mamillares) from which the olfac-
tory nerves of the first pair proceed. These are of very con-
[Seite 215] siderable magnitude, particularly in the herbivorous animals.*
They contain a continuation of the lateral ventricle; which
circumstance has formerly given rise to great physiological
errors.

§ 210. The structure of the corpora quadrigemina and
candicantia distinguishes the brain of herbivorous from that
of carnivorous quadrupeds. The nates very considerably ex-
ceed the testes in size, in the former class, while these propor-
tions are reversed in the latter instance. The herbivora have
a single large eminentia candicans; there are two small ones
in the carnivora.

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 ventricle 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 cor-
tical eminence (processus mamillaris) filling the ethmoidal fossa. As
the cetacea have no organ of smelling, their brain has neither olfactory
nerve, nor mamillary process.

The annexed tables representing the dimensions of the cerebrum,
cerebellum, corpora quadrigemina, medulla oblongata, and medulla
spinalis, calculated to five decimal parts of the French metre, in the
four classes of vertebrated animals, are taken from the celebrated
work of M. Serres sur l’Anatomie comparée du Cerceau dans les quatre
Classes des Animaux vertébrés.

[Seite 216]

DIMENSIONS
OF
THE LOBES OF THE CEREBRUM IN MAMMALIA.

MEASURES
Of the Lobes of the Cerebrum.
Antero-
posterior
diameter.
Transverse
diameter.
Vertical
diameter.
Metre.* Metre. Metre.
Man 0,17000 0,07500 0,09000
NAMES OF ANIMALS.
Simia rubra (red ape of Senegal) 0,07700 0,03300 0,05600
S. sylvanus (Barbary ape) 0,07200 0,02950 0,04300
S. cynocephalus (dog-faced baboon) 0,07000 0,02825 0,04500
S. sphynx (long-tailed baboon) 0,08200 0,03400 0,05700
S. maimon (mandrill) 0,08100 0,03200 0,04900
S. apella (sajou) 0,05900 0,04300
Lemur macaco (maki vari) 0,04500 0,02125 0,02900
Ursus arctos (brown bear) 0,09300 0,04300 0,06100
U. Americanus (American black bear) 0,08300 0,03650 0,04800
U. lotor (racoon) 0,05000 0,02150 0,02900
U. meles (badger) 0,05400 0,02400 0,03200
Viverra narica (brown civet) 0,04900 0,01850 0,03150
Mustela foina (martin) 0,03900 0,01700 0,02400
M. lutra (otter) 0,05200 0,02400 0,03400
Canis familiaris (domestic dog) 0,06000 0,02950 0,04400
C. lupus (young wolf) 0,05600 0,02550 0,03200
C. vulpes (fox) 0,03600 0,01750 0,02800
C. hyaena (hyaena) 0,06600 0,02950 0,04100
Felis leo (lion) 0,09100 0,04050 0,04800
F. tigris (tiger) 0,09400 0,04250 0,06400
F. onça (jaguar) 0,08100 0,03250 0,04800
F. pardus (panther) 0,07800 0,03400 0,05000
F. discolor (couguar, or American
lion)}
0,07100 0,02950 0,04200
F. lynx (lynx) 0,06100 0,02750 0,04200
Phoca vitulina (common seal) 0,10100 0,04900 0,04400
Didelphis Virginiana (opossum) 0,02200 0,01050 0,01450
[Seite 217]

Dimensions of the Lobes of the Cerebrum in Mammalia.
[Continued.]



NAMES OF ANIMALS.
MEASURES
Of the Lobes of the Cerebrum.
Antero-post.
diameter.
Transverse
diameter.
Vertical
diameter.
Metre. Metre. Metre.
Macropus major (kangaroo) 0,05300 0,02350 0,03800
Phascolomys (wombat) 0,04400 0,02100 0,02750
Castor fiber (beaver) 0,04200 0,02400 0,02700
M. alpinus (marmot of the Alps) 0,02975 0,01466 0,01950
Sciurus vulgaris (squirrel) 0,02025 0,01150 0,01400
Cavia acuti (agouti) 0,03500 0,01550 0,02200
Dasypus sexcinctus (armadillo) 0,02650 0,01300 0,01700
Sus tajassu (pecari) 0,06600 0,02450 0,03700
Hyrax capensis (marmot of the
Cape)}
0,03300 0,01250 0,02100
Camelus dromedarius (dromedary) 0,10500 0,05050 0,05800
C. llacma (lama) 0,08000 0,03450 0,04500
C. capreolus (roebuck) 0,06200 0,02600 0,04300
Common sheep 0,05800 0,02650 0,04300
Delphinus delphis (dolphin) 0,09500 0,05850 0,08200
D. phocaena (porpoise) 0,08600 0,06650 0,05000
[Seite 218]

DIMENSIONS
OF
THE CEREBELLUM IN MAMMALIA.

MEASURES
Of the Cerebellum.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
Man 0,12000 0,06000
NAMES OF ANIMALS.
Simia rubra (red ape of Senegal) 0,04500 0,02433
S. sabaea (callitriche) 0,03100 0,01800
S. sylvanus (Barbary ape) 0,03900 0,02400
S. cynocephalus (dog-faced baboon) 0,03800 0,02000
S. sphynx (long-tailed baboon) 0,04200 0,02650
S. maimon (mandrill) 0,05166 0,02900
S. apella (sajou) 0,03600 0,02400
Lemur macaco (maki) 0,03050 0,02200
Rhinolophus unihastatus (horse-shoe bat) 0,00900 0,00500
Vespertilio murinus (rear mouse) 0,00800 0,00400
Talpa Europaea (mole) 0,01400 0,00925
Ursus arctos (brown bear) 0,06200 0,03400
U. Americanus (American black bear) 0,05900 0,03500
U. lotor (racoon) 0,03100 0,01900
U. meles (badger) 0,03800 0,02100
Mustela foina (martin) 0,02800 0,01450
M. martes (pine-martin) 0,02400 0,01400
M. lutra (otter) 0,02300 0,01800
Canis familiaris (domestic dog) 0,04200 0,02525
C. lupus (young wolf) 0,03400 0,01700
C. hyaena (hyaena) 0,04000 0,02100
Felis leo (lion) 0,05500 0,03200
F. tigris (tiger) 0,05300 0,03900
F. onça (jaguar) 0,05400 0,03550
F. pardus (panther) 0,04850 0,03200
F. discolor (couguar, or American lion) 0,04900 0,02500
F. lynx (lynx) 0,03900 0,02650
[Seite 219]

Dimensions of the Cerebellum in Mammalia
[Continued.]



NAMES OF ANIMALS.
MEASURES
Of the Cerebellum.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
Phoca vitulina (common seal) 0,07250
Didelphis Virginiana (opossum) 0,02000 0,01200
Macropus major (kangaroo) 0,03800 0,02600
Phascolomys (wombat) 0,02200 0,01800
Castor fiber (beaver) 0,03500 0,02000
Mus typhlus (blind rat) 0,01300 0,00700
M. alpinus (marmot of the Alps) 0,02450 0,01200
Hystrix cristata (crested porcupine) 0,03000 0,01800
Lepus cuniculus (rabbit) 0,01600 0,00900
Cavia acuti (agouti) 0,02300 0,01700
Dasypus sexcinctus (armadillo) 0,02500 0,01300
Sus tajassu (pecari) 0,03500 0,02200
Hyrax capensis (marmot of the Cape) 0,01400 0,01400
Camelus dromedarius (dromedary) 0,07100 0,04600
C. llacma (lama) 0,04900 0,03400
C. capreolus (roebuck) 0,03900 0,03200
Capra hircus (goat) 0,04400 0,03900
Common sheep 0,03000 0,02700
Delphinus delphis (dolphin) 0,08500 0,04500
D. phocaena (porpoise) 0,07800 0,03300
[Seite 220]

DIMENSIONS
OF
THE CORPORA QUADRIGEMINA IN MAMMALIA.

MEASURES
Of the Corp. Quad.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
Man 0,01000 0,01100
NAMES OF ANIMALS.
Simia rubra (red ape of Senegal) 0,00625 0,00900
S. sabaea (callitriche) 0,00600 0,00750
S. Faunus (malbrook) 0,00700 0,00833
S. sylvanus (Barbary ape) 0,00650 0,00900
S. silenus (wanderow) 0,00575 0,00800
S. cynocephalus (dog-faced baboon) 0,00600 0,00733
S. sphynx (long-tailed baboon) 0,00625 0,01000
S. maimon (mandrill) 0,00650 0,01000
S. capucina (sai) 0,00450 0,00850
Lemur macaco (maki) 0,00550 0,00925
Rhinolophus unihastatus (horse-shoe bat) 0,00300 0,00300
Vespertilio murinus (rear mouse) 0,00250 0,00250
Talpa Europaea (mole) 0,00333 0,00500
Ursus arctos (brown bear) 0,00850 0,01200
U. Americanus (American black bear) 0,00875 0,01200
U. lotor (racoon) 0,00625 0,00900
U. meles (badger) 0,00600 0,01000
Mustela foina (martin) 0,00566 0,00800
M. martes (pine-martin) 0,00550 0,00725
M. lutra (otter) 0,00500 0,00800
Canis familiaris (domestic dog) 0,00700 0,00975
C. lupus (young wolf) 0,00700 0,00950
C. hyaena (hyaena) 0,01000 0,01275
Viverra civetta (civet) 0,00775 0,00950
V. genetta (genet-cat) 0,00650 0,00875
Felis leo (lion) 0,01200 0,01700
F. tigris (tiger) 0,01000 0,01300
[Seite 221]

Dimensions of the Corpora Quadrigemina in Mammalia.
[Continued.]



NAMES OF ANIMALS.
MEASURES
Of the Corp. Quad.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
F. onça (jaguar) 0,00950 0,01200
F. pardus (panther) 0,00950 0,01200
F. paradalis (ocelot) 0,00775 0,01250
F. discolor (couguar, or American lion) 0,01000 0,01200
F. jubata (Indian tiger) 0,00550 0,01150
F. lynx (lynx) 0,00900 0,01200
F. catus (cat) 0,00900 0,01200
Phoca vitulina (common seal) 0,00950 0,01500
Didelphis Virginiana (opossum) 0,00600 0,00750
Macropus major (kangaroo) 0,00500 0,01400
Phascolomys (wombat) 0,00700
Castor fiber (beaver) 0,00700 0,01000
Mus typhlus (blind rat) 0,00400 0,00600
M. alpinus (marmot of the Alps) 0,00550 0,00900
Hystrix cristata (crested porcupine) 0,00600 0,00575
Lepus cuniculus (rabbit) 0,00425 0,00700
Cavia acuti (agouti) 0,00550 0,00700
C. paca (paca) 0,00775
C. Cobaya (Guinea-pig) 0,00100 0,00750
Dasypus sexcinctus (armadillo) 0,00550 0,00550
Sus tajassu (pecari) 0,00550 0,01500
S. scropha (wild boar) 0,01000 0,01500
Hyrax capensis (marmot of the Cape) 0,00450 0,00700
Equus caballus (horse) 0,01950 0,02275
Camelus dromedarius (dromedary) 0,01250 0,02125
C. llacma (lama) 0,01125 0,01800
Antilope kevella (kevel) 0,00950 0,01700
A. gazella (gazelle) 0,00933 0,01475
A. rupicapra (chamois) 0,00925 0,00750
Cervus elaphus (stag) 0,01400 0,02100
C. dama (fallow deer) 0,01300 0,01700
[Seite 222]

Dimensions of the Corpora Quadrigemina in Mammalia.
[Continued.]



NAMES OF ANIMALS.
MEASURES
Of the Corp. Quad.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
C. capreolus (roebuck) 0,01050 0,01500
Capra hircus (goat) 0,00800 0,01300
Bos taurus (ox) 0,00900 0,01500
Common sheep. 0,00800 0,01400
Delphinus delphis (dolphin) 0,00700 0,02475
[Seite 223]

DIMENSIONS
OF
THE MEDULLA OBLONGATA IN MAMMALIA.

MEASURES
Of the Medulla
Oblongata.
Metre.
Man 0,02000
NAMES OF ANIMALS.
Simia rubra (red ape of Senegal) 0,01375
S. sylvanus (Barbary ape) 0,01300
S. cynocephalus (dog-faced baboon) 0,01150
S. nemestrina (maimon) 0,01400
S. rhesus (rhesus) 0,01500
S. sphynx (long-tailed baboon) 0,01400
S. maimon (mandrill) 0,01500
S. leucophea (drill) 0,01450
Lemur macaco (maki) 0,01266
Rhinolophus unihastatus (horse-shoe bat) 0,00450
Vespertilio murinus (rear mouse) 0,00350
Erinaceus Europaeus (hedgehog) 0,00700
Talpa Europaea (mole) 0,00700
Ursus arctos (brown bear) 0,02100
U. Americanus (American black bear) 0,02100
U. lotor (racoon) 0,01300
U. meles (badger) 0,01700
Viverra narica (brown civet) 0,01400
V. nasua (red civet) 0,01500
Mustela foina (martin) 0,01300
M. lutra (otter) 0,01300
Canis familiaris (domestic dog) 0,02000
C. lupus (young wolf) 0,01050
C. vulpes (fox) 0,01300
C. hyaena (hyaena) 0,01900
Viverra cafra (civet of the Cape) 0,01000
Felis leo (lion) 0,02400
F. tigris (tiger) 0,02400
F. onça (jaguar) 0,02250
F. pardus (panther) 0,01450
[Seite 224]

Dimensions of the Medulla Oblongata in Mammalia.
[Continued.]


NAMES OF ANIMALS.
MEASURES
Of the Medulla
Oblongata.
Metre.
F. discolor (couguar, or American lion) 0,02150
F. lynx (lynx) 0,01600
Phoca vitulina (common seal) 0,02300
Didelphis Virginiana (opossum) 0,01100
Macropus major (kangaroo) 0,02200
Phascolomys (wombat) 0,01700
Castor fiber (beaver) 0,01600
Mus nitela (lerot) 0,00450
M. typhlus (blind rat) 0,00600
M. alpinus (marmot of the Alps) 0,01200
Sciurus vulgaris (squirrel) 0,00900
Cavia acuti (agouti) 0,01200
Dasypus sexcinctus (armadillo) 0,01500
Sus tajassu (pecari) 0,02100
Hyrax capensis (marmot of the Cape) 0,00950
Equus caballus (horse) 0,03200
E. asinus (ass) 0,02500
E. zebra (zebra) 0,02400
Camelus dromedarius (dromedary) 0,03600
C. llacma (lama) 0,02500
Cervus elaphus (stag) 0,01900
C. capreolus (roebuck) 0,02100
Goat of Upper Egypt 0,01900
Bos taurus (ox) 0,03350
Common sheep 0,01600
Delphinus delphis (dolphin) 0,01900
D. phocaena (porpoise) 0,01600
[Seite 225]

DIMENSIONS
OF
THE MEDULLA SPINALIS IN MAMMALIA.

MEASURES
Of the Medulla
Spinalis.
Metre.
Man 0,01100
NAMES OF ANIMALS.
Simia rubra (red ape of Senegal) 0,00900
S. sylvanus (Barbary ape) 0,00800
S. cynocephalus (dog-faced baboon) 0,00900
S. nemestrina (maimon) 0,00700
S. rhesus (rhesus) 0,00775
S. sphynx (baboon) 0,01000
S. maimon (mandrill) 0,00950
S. leucophea (drill) 0,00800
S. apetla (sajou) 0,00550
Lemur macaco (maki) 0,00800
Rhinolophus unihastatus (horse-shoe bat) 0,00200
Vespertilio murinus (rear mouse) 0.00200
Erinaceus Europaeus (hedgehog) 0,00400
Talpa Europaea (mole) 0,00350
Ursus arctos (brown bear) 0,01700
U. Americanus (American black bear) 0,01300
U. lotor (racoon) 0,00800
U. meles (badger) 0,00800
Viverra narica (brown civet) 0,00800
V. nasua (red civet). 0,01050
Mustela foina (martin) 0,00700
M. lutra (otter) 0,00750
Canis familiaris (domestic dog) 0,01100
C. lupus (young wolf) 0,00600
C. vulpes (fox) 0,00900
C. hyaena (hyaena) 0,01300
Viverra cafra (civet of the Cape) 0,00650
Felis leo (lion) 0,01700
F. tigris (tiger) 0,01600
F. onça (jaguar) 0,01400
[Seite 226]

Dimensions of the Medulla Spinalis in Mammalia.
[Continued.]


NAMES OF ANIMALS.
MEASURES
Of the Medulla
Spinalis.
Metre.
F. pardus (panther) 0,01300
F. discolor (couguar, or American lion) 0,01200
F. lynx (lynx) 0,01100
Phoca vitulina (common seal) 0,01150
Macropus major (kangaroo) 0,01200
Phascolomys (wombat) 0,00000
Castor fiber (beaver) 0,00800
Mus nitela (lerot) 0,00325
M. typhlus (blind rat) 0,00300
M. alpimis (marmot of the Alps) 0,00450
Sciurus vulgaris (squirrel) 0,00500
Cavia acuti (agouti) 0,00700
Dasypus sexcinctus (armadillo) 0,00900
Sus tajassu (pecari) 0,01050
Hyrax Capensis (marmot of the Cape) 0,00550
Equus caballus (horse) 0,02000
E. asinus (ass) 0,01500
E. zebra (zebra) 0,01400
Camelus dromedarius (dromedary) 0,01900
C. llacma (lama) 0,01200
Cervus elaphus (stag) 0,00800
C. capreolus (roebuck) 0,01300
Goat of Upper Egypt 0,01100
Bos taurus (bull) 0,01900
Common sheep 0,00900
Delphinus delphis (dolphin) 0,01000
D. phocaena (porpoise) 0,00800

birds.

[Seite 227]

§ 211. The dura mater forms, in some birds, a falciform
process; which has been erroneously asserted to be deficient
in the whole class.* In the cock of the woods, (tetrao urogal-
lus
) it has a bony structure resembling that of the ornitho-
rhynchus.

§ 212. 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 striking-
ly distinguished from that of the following order. It differs,
however, from that of the mammalia, not only in the smooth-
ness of its surface, and the want of convolutions, but also in
the structure of the optic thalami. These eminences, which
are nearly spherical, 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 with the two
classes of cold and red blooded animals. Those eminences
also, which in the mammalia are justly termed corpora striata,
are of an uniform colour in birds.

Cuvier represents the brain of birds to consist of six tubercles, visi-
ble exteriorly; viz. the two hemispheres, the optic thalami, a cere-
bellum, and medulla oblongata.

[Seite 228]

DIMENSIONS
OF
THE LOBES OF THE CEREBRUM IN BIRDS.



NAMES OF BIRDS.
MEASURES
Of the Lobes of the Cerebrum.
Antero-post.
diameter.
Transverse
diameter.
Vertical
diameter.
Metre. Metre. Metre.
Vultur fulvus (vulture) 0,03200 0,02200 0,01550
Falco fulvus (common eagle) 0,03200 0,02400 0,02100
F. ossifragus (sea eagle) 0,02800 0,01900 0,02100
F. aeruginosus (buzzard) 0,01200 0,01400 0,01200
F. buteo (hawk) 0,01700 3,01500 0,01350
F. communis (falcon) 0,01900 0,01450 0,01200
Strix bubo (great horned owl) 0,02500 0,01800 0,02000
Motacilla regulus (gold-crowned
wren)}

0,09000

0,00600

0,00550
Hirundo rustica (swallow) 0,01000 0,00600 0,00600
Alauda arvensis (lark) 0,01100 0,00700 0,00650
Fringilla domestica (sparrow) 0,01100 0,00650 0,00700
F. coelebs (chaffinch) 0,01200 0,00700 0,00700
F. linaria (linnet) 0,01150 0,00650 0,00600
F. canaria (canary-bird) 0,01200 0,00600 0,00700
Corvus pica (magpie) 0,02000 0,01400 0,01200
African parrot 0,02900 0,01400 0,01700
Meleagris gallopavo (turkey) 0,01750 0,01250 0,01200
Phasianus gallus (common fowl) 0,01800 0,01200 0,01200
P. nycthemerus (silver pheasant) 0,01475 0,01233 0,01100
Struthio camelus (ostrich) 0,01550 0,01200 0,01200
S. casuarius (cassowary) 0,03800 0,02200 0,02400
Otis tarda (bustard) 0,04500 0,02350 0,02000
Ardea ciconia (white stork) 0,02200 0,01450 0,01400
A. pavonina (royal crane) 0,02400 0,01600 0,01900
Goeland 0,02000 0,01350 0,01300
Pelecanus Bassanus (solan goose) 0,01300 0,02000 0,02100
Anas anser (goose) 0,02500 0,01300 0,01400
A. bernicla (barnacle goose) 0,02700 0,02500 0,01700
A. moschata (musk duck) 0,02460 0,02700 0,01150
A. mollissima (eider duck) 0,02200 0,02450 0,01700
[Seite 229]

DIMENSIONS
OF
THE CEREBELLUM IN BIRDS.



NAMES OF BIRDS.
MEASURES
Of the Cerebellum.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
F. ossifragus (sea eagle) 0,01050 0,02033
F. aeruginosus (buzzard) 0,01400 0,01250
F. buteo (hawk) 0,01500 0,01600
Strix ulula (owl) 0,01125 0,01400
Motacilla regulus (gold-crowned wren) 0,00300 0,00400
Hirundo urbica (swallow) 0,00500 0,00600
Alauda arvensis (lark) 0,00700 0,00500
Fringilla domestica (sparrow) 0,00500 0,00525
F. coelebs (chaffinch) 0,00600 0,00400
F. linaria (linnet) 0,00650 0,00500
F. canaria (canary bird) 0,00500 0,00525
F. carduelis (goldfinch) 0,00500 0,00400
Loxia chloris (greenfinch) 0,00600 0,00575
Corvus pica (magpie) 0,01100 0,01150
C. corax (crow) 0,01100 0,01300
Amazonian parrot 0,01700 0,01300
African parrot 0,01300 0,01200
Turtle-dove 0,00900 0,01000
Meleagris gallopavo (turkey) 0,01350 0,01600
Phasianus gallus (common fowl) 0,00900 0,01100
P. nycthemerus (silver pheasant) 0,01100 0,01025
P. pictus (golden pheasant) 0,01200 0,01100
Tetrao cinereus (partridge) 0,01075 0,00950
Struthio camelus (ostrich) 0,01750 0,02500
S. casuarius (cassowary) 0,01900 0,02200
Otis tarda (bustard) 0,00975 0,01800
Ardea pavonina (royal crane) 0,01050 0,01800
Goeland 0,01200 0,01700
Anas mollissima (eider duck) 0,01000 0,01800
[Seite 230]

DIMENSIONS
OF
THE CORPORA QUADRIGEMINA IN BIRDS.



NAMES OF ANIMALS.
MEASURES
Of the Corp. Quad.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
Vultus fulvus (vulture) 0,00800 0,01200
Falco chrysaetos (golden eagle) 0,00800 0,01200
F. ossifragus (sea eagle) 0,01100 0,01100
F. communis (falcon) 0,00725 0,00775
F. aeruginosus (buzzard) 0,00550 0,00900
F. buteo (hawk) 0,00600 0,00900
Motacilla regulus (gold-crowned wren) 0,00300 0,00250
Hirundo urbica (swallow) 0,00475 0,00450
Alauda arvensis (lark) 0,00425 0,00400
Fringilla domestica (sparrow) 0,00400 0,00350
F. coelebs (chaffinch) 0,00400 0,00400
F. linaria (linnet) 0,00300 0,00300
F. canaria (canary bird) 0,00325 0,00300
F. carduelis (goldfinch) 0,00325 0,00300
Loxia chloris (greenfinch) 0,00400 0,00350
C. pica (magpie) 0,00600 0,00600
Amazonian parrot 0,00625 0,01000
African parrot 0,00600 0,00700
Meleagris gallopavo (turkey) 0,00725 0,00875
Phasianus gallus (common fowl) 0,00800 0,00900
P. nycthemerus (silver pheasant) 0,00850 0,00900
P. pictus (golden pheasant) 0,00700 0,00800
Struthio camelus (ostrich) 0,01125 0,01100
S. casuarius (cassowary) 0,01000 0,01050
Otis tarda (bustard) 0,00800 0,00775
Ardea ciconia (white stork) 0,00800 0,01200
A. pavonina (royal crane) 0,00900 0,00900
Goeland 0,00800 0,00800
[Seite 231]

Dimensions of the Corpora Quadrigemina in Birds.
[Continued.]



NAMES OF BIRDS.
MEASURES
Of the Corp. Quad.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
Pelecanus Bassanus (solan goose) 0,00900 0,01100
Anas anser (goose) 0,00700 0,00850
A. bernicla (barnacle goose) 0,00650 0,00900
A. moschata (musk duck) 0,00800 0,00975
A. mollissima (eider duck) 0,00600 0,00625
[Seite 232]

DIMENSIONS
OF
THE MEDULLA OBLONGATA IN BIRDS.


NAMES OF BIRDS.
MEASURES
Of the Medulla
Oblongata.
Metre.
Vultus fulvus (vulture) 0,01100
Falco chrysaetos (royal eagle) 0,01400
F. ossifragus (sea eagle) 0,01700
F. communis (falcon) 0,00800
F. aeruginosus (buzzard) 0,00900
F. buteo (hawk) 0,00900
Strix bubo (great horned owl) 0,00900
Motacilla regulus (gold-crowned wren) 0,00300
Hirundo urbica (swallow) 0,00350
Alauda arvensis (lark) 0,00400
Fringilla domestica (sparrow) 0,00375
F. coelebs (chaffinch) 0,00450
F. linaria (linnet) 0,00375
F. canaria (canary bird) 0,00300
F. carduelis (goldfinch) 0,00300
Loxia chloris (greenfinch) 0,00400
C. pica (magpie) 0,00800
Amazonian parrot 0,01000
African parrot 0,00900
Meleagris gallopavo (turkey) 0,00950
Phasianus gallus F. (common fowl, hen) 0,01000
Phasianus gallus M. (cock) 0,01100
Capon 0,00800
P. nycthemerus (silver pheasant) 0,01025
P. pictus (golden pheasant) 0,00950
Columba palumbus (pigeon) 0,00600
Tretrao cinereus (grey partridge) 0,00550
Struthio camelus (ostrich) 0,01600
S. casuarius (cassowary) 0,01600
Otis tarda (bustard) 0,01000
Ardea ciconia (white stork) 0,01533
A. nigra (black stork) 0,01400
A. pavonina (royal crane) 0,00900
[Seite 233]

Dimensions of the Medulla Oblongata in Birds.
[Continued.]


NAMES OF BIRDS.
MEASURES
Of the Medulla
Oblongata.
Metre.
Goeland 0,01000
Pelecanus Bassanus (solan goose) 0,01400
Anas anser (goose) 0,01050
A. bernicla (barnacle goose) 0,01100
A. moschata (musk duck) 0,01400
A. boschus (common duck) 0,01400
A. mollissima (eider duck) 0,01100
[Seite 234]

DIMENSIONS
OF
THE MEDULLA SPINALIS IN BIRDS.


NAMES OF BIRDS.
MEASURES
Of the Medulla
Spinalis.
Metre.
Vultus fulvus (vulture) 0,00800
Falco chrysaetos (royal eagle) 0,00800
F. ossifragus (sea eagle) 0,00600
F. communis (falcon) 0,00500
F. aeruginosus (buzzard) 0,00550
F. buteo (hawk) 0,00400
Strix bubo (great horned owl) 0,00600
Motacilla regulus (gold-crowned wren) 0,00125
Hirundo urbica (swallow) 0,00175
Alauda arvensis (lark) 0,00225
Fringilla domestica (sparrow) 0,00175
F. coelebs (chaffinch) 0,00233
F. linaria (linnet) 0,00150
F. canaria (canary bird) 0,00150
F. carduelis (goldfinch) 0,00200
Loxia chloris (greenfinch) 0,00200
C. pica (magpie) 0,00450
Amazonian parrot 0,00400
African parrot 0,00400
Meleagris gallopavo (turkey) 0,00500
Phasianus gallus F. (common fowl, hen) 0,00425
Phasianus gallus M. (cock) 0,00475
P. nycthemerus (silver pheasant) 0,00550
P. pictus (golden pheasant) 0,00500
Columba palumbus (pigeon) 0,00400
Tetrao cinereus (grey partridge) 0,00300
Struthio camelus (ostrich) 0,00700
S. casuarius (cassowary) 0,00800
Otis tarda (bustard) 0,00600
Ardea ciconia (white stork) 0,00750
A. nigra (black stork) 0,00700
A. pavonina (royal bird) 0,00500
Goeland 0,00500
[Seite 235]

Dimensions of the Medulla Spinalis in Birds.
[Continued.]


NAMES OF BIRDS.
MEASURES
Of the Medulla
Spinalis.
Metre.
Pelecanus bassanus (solan goose) 0,00750
Anas anser (goose) 0,00600
A. bernicla (barnacle goose) 0,00600
A. moschata (musk duck) 0,00700
A. boschus (common duck) 0,00675
A. mollissima (eider duck) 0,00600
[Seite 236]

§ 213. The brain of birds does not possess several parts,
which are found in that of the mammalia, 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 description of
parts, which are certainly absent. The existence of the for-
nix, pineal gland, corpora candicantia and quadrigemina, is a
matter of dispute.*

amphibia.

§ 214. Anatomists have hitherto bestowed but little labour,
comparatively speaking, on the brain of amphibia. It is small
and simple, and consists of five roundish eminences; viz. the
two hemispheres, the two thalami nervorum opticorum, lying
behind these, and separate from them, and excavated by a
ventricle; and the cerebellum, which in both classes of cold
red-blooded animals contains no arbor vitae. The spinal mar-
row, compared with the brain, is of astonishing magnitude in
most amphibia.

The dura matter forms no processes in the amphibia, nor in the
fishes.

[Seite 237]

DIMENSIONS
OF THE
LOBES OF THE CEREBRUM IN REPTILES.



NAMES OF ANIMALS.
MEASURES
Of the Lobes of the Ce-
rebrum.
Antero-post.
diameter.
Transverse
diameter.
Metre. Metre.
Testudo graeca (tortoise) 0,01600 0,00500
T. mydas (green turtle) 0,01900 0,01000
Crocodilus Niloticus, (common crocodile) 0,00800 0,00500
Adult crocodile 0,01800 0,01500
C. sclerops (alligator) 0,00700 0,00400
C. lucius (pike-headed alligator) 0,02100 0,01100
L. agilis (grey lizard) 0,00500 0,00275
Lacerta viridis (green lizard) 0,00350 0,00250
Tupinambis 0,00400 0,00300
L. Africana (common chameleon) 0,00600 0,00333
Anguis fragilis (blind-worm) 0,00250 0,00200
Amphisbaena 0,00500 0,00300
Coluber beras (adder) 0,00400 0,00300
Ringed snake 0,00550 0,00400
C. hajé (hajé viper) 0,00575 0,00400
Rana esculenta (common frog) 0,00500 0,00400
[Seite 238]

DIMENSIONS
OF
THE CEREBELLUM IN REPTILES.



NAMES OF ANIMALS.
MEASURES
Of the Cerebellum.
Transverse
diameter.
Antero-post.
diameter.
Metre. Metre.
Testudo graeca (tortoise) 0,00400 0,00300
T. mydas (green turtle) 0,01125 0,01100
Crocodilus Niloticus (common crocodile) 0,00500 0,00400
C. sclerops (alligator) 0,00400 0,00300
C. lucius (pike-headed alligator) 0,01400 0,01000
L. agilis (grey lizard) 0,00150 0,00150
Lacerta viridis (green lizard) 0,00175 0,00150
Tupinambis 0,00350 0,00500
L. Africana (common chameleon) 0,00375 0,00175
Anguis fragilis (blind-worm) 0,00100 0,00100
Coluber beras (adder) 0,00200 0,00233
Ringed snake 0,00175 0,00200
C. hajé (hajé viper) 0,00175 0,00200
Rana esculenta (common frog) 0,00300 0,00200
[Seite 239]

DIMENSIONS
OF THE
CORPORA QUADRIGEMINA IN REPTILES.



NAMES OF ANIMALS.
MEASURES
Of the Corp. Quad.