THE LIBRARY

OF

THE UNIVERSITY
OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID

A MANUAL

ZOOLOGY.

WORKS BY THE SAME AUTHOR.
A MANUAL OF HUMAN ANATOMY,

Descriptive, Practical, and General. Illustrated by 200
highly -finished Wood Engravings by Dr. WESTMACOTT.

Foolscap, cloth, price 12s. 6d.

A MANUAL OF ARTISTIC ANATOMY,

for the Use of Sculptors, Painters, and Amateurs.
Foolscap, cloth, price 7s. 6d.

THE RACES OF MEN. A Philosophical Inquiry
into the Influence of Race over the Destinies of Nations.
Second Edition, with Supplementary Chapters,

Crown 8vo, cloth, price 10s. 6d.

A

MANUAL

ZOOLOGY.

BY M. MILNE EDWARDS.

TRANSLATED FROM THB LAST FRENCH EDITION

BY R. KNOX, M.D., E.R.S.E.

SECOND EDITION.

WITH MANY ADDITIONAL OBSERVATIONS, AND ILLUSTRATED BY
572 HIGHLY-FINISHED WOOD ENGRAVINGS.

EDITED BY

C. CARTER BLAKE, F.G.S., F.A.S.L.

SECRETARY OF THE ANTHROPOLOGICAL SOCIETY OF LONDON,
LECTURER ON ZOOLOGY, LONDON INSTITUTION, ETC.

HENRY RENSHAW,

356, STRAND, LONDON.

1863.

LONDON :

SAVILL AND EDWARDS, PRINTERS,
CHANDOS STREET.

Bvo-lo

TABLE OF CONTENTS.

Preliminary Ideas . . .

Division of Natural Bodies
into Three Kingdoms .

Relations under which Liv-
ing Beings are Studied

PAGE
1

PAGE

General Characters of Ani-
mals 6

Organic Tissues and Organs
of Animals .... 7

Classification of Functions 9

CONFORMATION AND CLASSIFICATION OF ANIMALS.

Functions of Nutrition . 11

Absorption ..... 12

Digestion 18

Blood 45

Circulation 50

Respiration 69

Exhalation 80

Secretions 81

Nutritive Assimilation and

Decomposition ... 87

Animal Heat 92

Functions of Relation . 94
Nervous System . .95

Sensibility 107

Touch 109

Taste Ill

Smell 112

Hearing 113

Sight 118

Movements 127

Voice 154

Intelligence and Instinct . 159

HISTORY OF THE PRINCIPAL PHYSIOLOGICAL FUNCTIONS.

Consideration of the Gene-
ral Plan of the Organiza-
tion 189

Zoological Classifications . 200
Division of the Animal
Kingdom into Primary
Divisions and into Classes 207

Vertebrate Animals . . 231

Mammals 233

Birds 305

Reptiles 348

Batrachia 364

Fishes 371

Articulata 405

IviSSOOOl

VI

TABLE OF CONTENTS.

PAGE

Articulated Animals . . 405

Insects 405

Myriapoda . ., . . .454

Arachnida 455

Crustacea 465

Worms (Vermes) . . . 497

Annelida 497

Rotifera 500

Turbellaria 502

Helminthia 502

Cestoiida 503

Mollusca 504

Mollusca, properly so called 504
Cephalopoda .... 507

PAGE

Gasteropoda 515

Pteropoda 519

Acephala 519

Mollusco'ida 522

Tunicata, properly so called 523

Briozoaria 523

Zoophytes 525

Echinodermata .... 526

Acalephae 528

Polyps 530

Infusoria 583

Spongiaria 534

The Geographical Distri-
bution of Animals . , 535

NOTICE TO THE FIRST EDITION.

THIS manual is one of three which, taken together, form the
Elementary Course of Natural History prescribed and sanc-
tioned by the Council of Public Instruction of France. The
Botanical work was written by the grandson of the celebrated
Jussieu; the Mineralogical and Geological portion of the course
by M. F. S. Beudant, a gentleman distinguished for his know-
ledge of these sciences ; the Zoological Manual, now for
the first time translated, is the production of my most
esteemed friend, M. Milne Edwards, one of the first of living
zoologists.

The work, in its original form, has already passed through
seven editions : a sure proof of its merit. It is admirably
adapted, by the simplicity of its style and practical character,
to form a safe text-book in all schools and colleges, and to
aid in that which I have never lost sight of, — namely, the
introduction of my favourite pursuit, Zoology, into univer-
sities as a recognised branch of general education.

Thinking it would be but an act of justice, though tardy,
to place before the English reader a work of an esteemed
friend, which, according to the fashion of the day, has formed
the stock in trade of so many English, Scotch, Irish, and
American literary contrabandists, I wrote M. Edwards on
the subject, and received from him the following letter, — a
b 2

viii NOTICE TO THE FIKST EDITION.

guarantee to the public that the Translation has been under-
taken with the Author's full approbation : —

" Vernet les Bains, Pyrenees Orientales,
le 28 Aout, 1855.

" Monsieur et cher Confrere, — II ne peut m'etre qne tres
agreable de voir paraitre sous vos auspices une traduction
anglaise de mon petit ouvrage elementaire de Zoologie;
aussitot mon retour a Paris j'aurais le plaisir de vous
adresser une exemplaire de la derniere edition. Le nombre
des exemplaires deja vendus s'elevent en tout a plus de
30,000 ; ce qui me fait esperer que la traduction anglaise se
placerait bien.

" Veuillez agreer, Monsieur et cher Confrere, la nouvelle
assurance de ma parfaite consideration.

(Signe) " MILNE EDWABDS."

" A M. le Docteur Knox."

As a scientific man, and a teacher of Anatomy and of the
great principles of Zoology to thousands, including the names
of many of the most celebrated scientific men of the day, I
ought not perhaps to notice the literary pirates to whom I
have just alluded, were it not that, during the last hundred
years they have, in despite of many excellent English writers,
greatly retarded the progress of Zoology in Britain and else-
where, wherever, indeed, the English language is spoken.
Carefully excluding from their compilations all elevated and
correct views of science, they have, by their anecdotic and
quasi-popular style, contributed to debase the works of the
most eminent zoologists to such an extent that the grand
labours of Buffon, the masterly researches of Cuvier, the
profound views of Goethe, Oken, and Spix can scarcely be
recognised. Their views are anti-scientific, anti-educational ;
calculated, if not devised, to retard the progress of the
human mind.

The translation being addressed to Englishmen, lovers of

NOTICE TO THE FIEST EDITION. IX

matters -of- fact in science as well as in other things, I have
done my best to avoid all repetitions, all French idioms, all
lengthened treatment of physiological and metaphysical
hypotheses; but in doing so I have scrupulously avoided
omitting any fact or idea or opinion of the author. The
anatomical details of the work I have endeavoured to give in
as brief, concise, and simple a manner as befits such matters.
Anatomy is a science of facts and of demonstrations ; even
when the objects are present, as in lectures (and this was the
original form of M. Edwards's work), it is a mistake to over-
load their description with terms, whether technical or popular :
my vast experience as a teacher of Anatomy early taught me
this. In French the error is less obvious than in English, a
language which does not readily accommodate itself to those
combinations of unclassical terms which all science unfor-
tunately requires ; which sound harshly to the ears of the
classical scholar, and have greatly retarded, no doubt, the
accomplishment of that object which is the aim of this work, —
namely, the introduction, in England, of Zoology as a branch
of primary education. •

R. K.

NOTICE TO THE SECOND EDITION.

ENCOUEAGED by the extraordinary patronage bestowed on
the first English edition of this work (the sale of 3500
copies), the translator has spared no pains to render this
new edition deserving the patronage already bestowed on the
first. He has added many new observations, derived as well
from his own researches as from those of others, and has
illustrated these by numerous additional wood engravings.
He trusts, therefore, that the new edition will be found au
courant with the present state of zoological knowledge in

Europe.

U.K.

LONDON, 1862.

NOTE TO SECOND EDITION.

MY late friend Dr. Knox having completed the revision of
the present edition of Milne Edwards's Manual of Zoology,
only survived to correct the proofs as far as the thirty-second
page. A short period after his lamented decease, Mr. Eenshaw
confided this editorial duty to me, with the expression of his
wish that, out of respect to the memory of the late Dr. Knox,
I should make as few alterations as possible. Having enjoyed
the privilege of the personal acquaintance of the venerable
anatomist until the period of his decease, I also was anxious

Xll NOTE TO SECOND EDITION.

to leave this posthumous edition of his translation of Milne
Edwards's work in the form in which Dr. Knox would have
desired it to appear, had he survived, and therefore, with
the exception of a few cases, in which an error of fact had
been inadvertently passed over, I have left the manuscript
untouched.

The present edition differs from the preceding by the intro-
duction of some graphic sketches by one of- Dr. Knox's most
distinguished pupils, the late Professor Edward Forbes.

Two Tables of Zoological Classification are appended, and
a Glossary, which it is thought may prove useful, has been
incorporated with an Index, which has been added for the
first time, in this edition.

C. C. B.

INTRODUCTION TO THE FIRST
EDITION.

THE task I have undertaken, and which I now complete, is
simple, and conformable to all my views, studies, and pursuits.
Esteem for the author and for a family I have long known,
induced me to undertake the translation of an elementary
work on Zoology occupying that difficult and doubtful position
in which all such works are of necessity placed. Addressed
to professional students, and yet not exclusively so, who,
partially educated, as the case may be, are about to qualify
themselves for embarking in some one or other of the great
professions which form the occupation of the intellectual
world, such studies seem uncalled for as barren of future
profitable results. That such a feeling prevails with most
professional students — using the term professional in its
widest acceptation — I am well aware ; indeed, as regards the
students of one of these learned professions, none can know
better, if so well, as I do. The Medical Director of the ana-
tomical studies of- many thousands of medical students, I
have ever found them adverse to science, strictly so called ;
especially to that branch of zoological science termed Natural
History. They desire to be practical. Zoology is not a prac-
tical art : in this view, therefore, it leads to nothing.

John Hunter had lived and laboured : his vast ideas, his
brilliant discoveries, his views, which seem more like inspira-

XIV INTRODUCTION TO THE FIRST EDITION.

tions than the natural result of an industry unsurpassed, lay
buried in the hall of a corporate body with whom, as a surgeon,
he was accidentally associated : but he had laboured in vain.
His views he placed before the world in the form of a museum,
to which none of the labours of men's hands can be compared
— unless it be, and these no doubt excel, the handiwork of
those who carved the Medicean Venus and the Belvidere
Apollo. Yet he had laboured in vain, for never, I believe, at
any period of its history, was Zoology in a lower condition in
Britain than that in which I found it when, returning from
France, in the summer of 1825, I submitted to a small but
select class an outline of those great views which France and
Germany had taught me, and which I have continued to
meditate and reflect on to the present day. Since that period
the educational institutions of the country have become
somewhat multiplied, perhaps improved. The pressure of
continental opinion has told on Britain, and ere long it is by
no means improbable the sciences of simple observation may
be deemed, if not equal in importance to those great branches
of human knowledge wrapped up in the study of numbers
and of literature, at least useful, practically calculated to
expand the intellect — the first object of all education.

It is a matter not only curious in itself, but fraught with
interest to the future historian, to trace, however briefly,
the gradual unfolding of modern education, as contrasted not
merely with the ancient but with that which, even in my
younger days, prevailed everywhere. The interest lies chiefly
in contrasting the low estimate which prevailed respecting
the nature and character of the sciences of simple observation,
as compared with true science ; that description of knowledge
which admits of a priori reasoning, from that which scarcely,
if at all, admits of such. Hence, no doubt, the exclusion of
chemistry, anatomy, natural history, from the curriculum of
all universities, schools, colleges, examining bodies. Medicine,
an art mistaken for a science, usurped their place, and these
branches of knowledge were tacked to medicine furtively, but

INTRODUCTION TO THE FIEST EDITION. XV

not mentioned or spoken of aloud. The sciences I speak of
were merely permitted to exist under a withered and degraded
form ; and a faculty which never ought to have had a place
in any university, came at last in some to play a prominent
part ; as if to complete the misapprehensions of true science,
it required only to add to these the mechanical art of surgery;
and this of course followed : nor could it have been otherwise
in a country where constants are alone looked on as valuable,
applicative, productive ; industrial facts bearing on the great
questions of profit and loss — direct, immediate, are alone
esteemed.

Generally speaking, the continental universities resisted
this pollution: they refused all association with faculties,
medical or otherwise, and more especially that of France ;
access to the scientific departments of the army was closed,
by the rigorous education and examination of the Polytechnic
School, to all who had not mastered the elements at least of
natural science ; whilst of the aspirant for the diploma of
medicine a first university degree was demanded. Now that
degree the candidate could not obtain if ignorant of those
branches of knowledge which constitute Natural History.
The necessity produced a want, namely, a brief manual of
instruction suited to such a case ; the want was supplied in
respect of Zoology by my friend M. Milne Edwards, whose
work in an English dress I now present to the public ;
the botanical manual was the work of a descendant of the
illustrious Jussieu; the miueralogical and geological by
Beudarit : the three comprising all Natural History, properly
so called.

But of one thing I am thoroughly convinced. This im-
proved condition of education, even in France, was the result
of accident, — of the accidental appearance in France of a man
destined to revolutionize all zoological science, viewed under
every possible aspect — that man was George Cuvier. To be
convinced of the truth of this view, we have but rapidly to
trace the history of Zoology from the period of the immortal

XVI INTRODUCTION TO THE FIBST EDITION.

Historia Animalium of Aristotle to that of St. Pierre and
Faujas St. Fond.*

Before Eome existed, and before the Iliad was composed,
Egypt had its Pyramids and its Thebes ; that land of prac-
tical science, bordered on regions of the earth surpassed by
none for variety in the forms of animal life. I allude to
Africa within the tropics. Nearly every animal susceptible
of domestication and useful to man had been appropriated by
the Coptic race of Egypt and Nubia ; whilst all the tcilde of
nature had in succession been exhibited to the nation in
various triumphal processions. But all this was merely prac-
tical and transitory. It was the same with Rome, Eastern
and Western; no science resulted from it, no zoological
science, at least ; and the dawn of civilization which re-opened
in Europe after the dreadful period of the Dark and 'Middle
Ages, found zoological and natural science precisely where it
was left by Pliny — a tissue of puerilities, of vague hypotheses,
of silly fancies, upon which no critique had ever been exercised.

Notwithstanding the occasional appearance of able men, it
continued in this sad state until the close of the seventeenth
century. Neither zoology nor mineralogy nor geology had
any real existence.

In 1707, or about that period, two men appeared, simulta-
neously, destined to rescue Zoology at last from the degraded
state to which Pliny and his imitators, abounding most in
England, had reduced it. These were Carl Linne and the
Count de Buffon. To these truly great men we owe the
first attempt to remove the natural sciences from the control
of those into whose hands they had fallen. The genius of
Linne led to classification, that of Buffon to description ; the
one defined, the other described. But the genius of the latter
was of a higher cast : it anticipated the future ; and men now
read with surprise and learn with astonishment (a surprise
and astonishment in which I do not partake) that Buffon
was no mere compiler, no mere literary man, no mere writer

* See Great Artists and Great Anatomists. London : Van Voorst.

INTRODUCTION TO THE FIRST EDITION. XV11

destined to captivate the world by the beauties of a style un-
matched, I believe, in France, but a profound philosopher,
who had already anticipated nearly all the great truths of the
transcendental in science. But neither Buffon nor Linne,
whatever might have been the profundity of their views,
offered any demonstration of these views. This is what the
world looks for, and rightly expects ; rigid demonstration
supported the Newtonian hypothesis, else Newton had written
in vain. Palissy, the potter, had said as much as Buffon,
but, like him, he had offered no demonstration, and the
world looked on them as dreamers — dangerous dreamers, of
whom the less notice that was taken the better. In Britain,
especially, Buffon's works appeared stripped of all their lofty
views, disfigured and degraded ; he passed, even in France,
merely as the naturalist who had best described the hot-
blooded quadrupeds, as certain mammals were called even in
my days ; the bold conjectures of Palissy and of Buffon
seemed about to disappear for ever from the field of science.
Even Goethe had failed to resuscitate them under other
forms. The geological theories of Hutton and Playfair were
met successfully by the plausible hypothesis of Werner, when
suddenly a man appeared, destined to place natural science
for ever on a basis which, if not so fixed as the Elements of
Euclid, will at least prove as enduring. That man was
George Cuvier, a German, born on French soil; an anatomist.
This wonderful man, of a rigidly demonstrative turn of mind,
when quite young, but well educated, bethought him of in-
vestigating " the unknown" in Zoology by means of ana-
tomical research, the only way in which it could be inquired
into. Linne and Buffon had described and defined the
exterior : " I will investigate," he said, " the interior :" they
ought to correspond : there must be intimate relations between
them ; anatomical co-relations. Seemingly, and without
being aware of it, he had discovered a new element of research
— descriptive anatomy ; not the vague comparative anatomy
of Perrault or Daubenton, but minute descriptive anatomy,

xvili INTBODUCTION TO THE FIEST EDITION.

worthy of Hunter and of himself. Yet he was very young,
and knew nothing of Hunter and but little of Daubenton.
Genius directed his steps, that genius which, when it appears,
and happily escapes the crushing influences " of established
socialisms," is sure to form a new era. Like most of the
great men of his day (products of the French revolution), he
had outstripped in his merest youth the age he lived in, and
rapidly shot beyond that which was to follow.

Cuvier's early pursuits were the rectification, by means of
anatomy, of the classifications of Buffoii and Linne ; but he
quickly, as it were instinctively, passed beyond this com-
paratively narrow field into one which has no limits. Whilst
pursuing his inquiries on the structure of the invertebrate
kingdom, he soon saw that the animal forms he dissected
differed specifically and generically from those fossil forms
which lay around him. Palissy, the potter, had seen the
same ; Buffon had announced the fact : they were declared to
be dreamers. Cuvier offered to mankind the Ossemens
Fossiles in proof that they were so, and from that moment to
the present day few have had the hardihood to deny the
proof ; none but those who regard the Newtonian demonsta-
tion as an idle unprofitable dream.

The importance thus given to zoological studies and pur-
suits by the application of the anatomical method in Zoology,
would have commenced and terminated with Cuvier but for
this one circumstance — he had created geology, palseontology ;
that last and most wonderful science, which seems to have no
limits. He had shown that without a knowledge of 'the
extinct zoologies there can be no geology, properly speaking;
none at least likely to interest man. Now this extinct
Zoology cannot be well understood, if at all, without a know-
ledge of the living zoology, that being the term and mean of
comparison. Thus was Zoology forced at last into the schools,
universities, and collegiate institutions.*

* Cuvier had shown anatomy to be the only safe basis for testing zoology,
and a comparison of it with the extinct the only guide to palaeontology ; it

INTEODUCTION TO THE FIEST EDITION. XIX

The necessity for this was first seen and admitted in France,
from whence it naturally was imported into England, where
Cuvier and his supposed views had become fashionable ; the
single geologist at the Board of Ordnance, MacCulloch,
was slowly replaced by a body of scientific men, each teach-
ing a different department of natural science : out of this
arose a school of practical geology, and various chairs in a
similar direction came to be founded in collegiate educational
institutions. The illustrious Sedgwick, to whom geology
unquestionably owes its present position in Britain, set an
example in Cambridge which cannot be too much praised
nor too closely followed.

Thus originated the gradual introduction of zoological
science into the curriculum of study for university honours
demanded of all, I presume, who mean to follow out a pro-
fessional vocation in Prance : England slowly follows. The
little work I here present to the public contains the best
outline ever yet published of such studies ; from me it requires
no praise ; its intrinsic merits and the numerous editions it
has already passed through constitute its best recommenda-
tion to the English reader.

E. K.

may be, and has been, called an empirical method, by which I presume is
meant that the method is not strictly scientific. I have all my life been of
this opinion, but the method notwithstanding has led to results second only,
if second, to the Newtonian discoveries.

ELEMENTARY COURSE

OF

ZOOLOGY.

PRELIMINARY IDEAS.

§ 1. Object and Utility of Natural History. — Natural
History is that science which treats of the structure of bodies
spread over the surface of the globe or forming its mass
— the phenomena exhibited by these bodies, the characters
by which they may be distinguished from each other, and
the part they play in the entire creation. Its range is im-
mense, and its importance is not inferior to its extent. Some,
but little acquainted with science, see in natural history
merely a collection of anecdotic facts, more calculated to
excite the curiosity than to exercise the understanding, or
a dry study of technical terms and arbitrary classifications.
Such an opinion is based on ignorance : and the utility of
the study of natural history cannot fail to be recognised by
all who possess even the preliminary ideas of the science.
The grand and harmonious view it presents of Nature,
whose beau ideal is so much superior to that of human
invention, tends to elevate the mind to lofty and sound
thoughts. The knowledge of ourselves and of surrounding
objects is not given merely to satisfy the desire for learning
which develops itself always according as the intelligence
enlarges ; it forms a necessary basis to many other studies,
and is eminently calculated to give to the judgment that recti-
tude in the absence of which the most brilliant qualities lose
their value, and in the course of life lead the mind astray.
On the other hand, to be convinced of the practical importance
of the natural sciences, we have only to look to geology and
mineralogy, and the services they have rendered to industry ;
to botany, and to the myriads of beauteous and useful plants

2 ZOOLOGY.

it describes, and to horticulture, of which it is the guide ; to
recollect the animals to which we owe wool, silk, honey —
which lend us that power which man so often requires, or
which, far from being useful to us, threaten our harvests with
destruction ; lastly, to consider the long catalogue of human
infirmities, and to reflect on the dangerous character of that
medicine which is not based on a scientific knowledge of the
human structure. But the utility of these sciences does not
stop here ; in an educational point of view, their study accus-
toms the mind to proceed from effect to cause, testing each
hypothesis by an appeal to facts. Finally, before all other
studies, that of natural history trains the mind to method,
that part of logic without which all investigation is laborious,
every exposition obscure.

In claiming for natural history a place in every liberal
system of education, we do not mean that all young men
should become naturalists. So vast a study and the time
required for other studies forbid such an idea ; nor would the
acquisition of the details on which natural history is based be
of any service to the young mind : all that is necessary is
that sound, correct notions be placed before the student, and
acquired by him, respecting the great questions to solve which
is the object of natural history studies ; on the constitution
of the globe, for example, and the physical revolutions which
succeed each other on its surface ; on the nature of plants and
animals ; on the mode in which their functions are exercised ;
and on the principal modifications of their structure, accord-
ing to the kind of life for which they are destined. This
description of knowledge once acquired is seldom forgotten;
it forms a basis for the special studies of those who desire
to become naturalists ; and is sufficient for those whose pur-
suits do not lead to science. The University (of France) in
its programme sanctions this course of study, and enforces it ;
in this work we propose adopting it.

§ 2. Division of Natural JBodies into Three Kingdoms. —
All natural bodies, whether spread over the surface of the
globe or collected in the interior of the earth, are of two
kinds — mineral or unorganized, living or organized. These
last are subdivided into two groups — vegetables and animals.
Hence has arisen the expression of the three great kingdoms
of nature — the mineral, vegetable, and animal. In com-
mencing the study of these three kingdoms, it is necessary to
inquire, in the first place, on what basis these divisions rest,

PEELIMINAET IDEAS. d

and to inquire into the fundamental differences which distin-
guish a mineral from a living body, a plant from an animal.

§ 3. Differences between Mineral or Inorganic Sub-
stances and Living Beings. — These differences are numerous
and striking ; they may be thus summed up. They differ in
their origin, mode of existence, duration, manner of decay or
destruction, general form, intimate structure, and elementary
composition.

§ 4. Thus, as to the mode of origin. — When a mineral
body is formed, it springs immediately from the union of
two or more substances, which, by their nature, differ essen-
tially from it, and which combine by reason of the chemical
affinities they possess. A living being, on the contrary, is
never thus spontaneously formed ; it springs from one re-
sembling itself, and the vitality essential to its formation is
transmitted in succession from an uninterrupted series of
individuals resembling each other. Two substances, in no
way resembling each other, chlorine and sodium, for example,
by their union form common salt, independent of the presence
of this third substance : not so the plant or animal ; for its
formation a parent is necessary, that is, a being resembling
it and preceding it in point of time. Such beings, then,
require for their formation a foreign impulse, and this they
can only receive from a parent.

§ 5. As respects their mode of existence. — The two classes
of bodies are equally distinct. Rocks and minerals remain
internally in a state of rest or repose ; if they gain any addi-
tional substance, it is by the accretion of matter similar to
them ; what they lose is accidental, and affects them not;
Living bodies, on the contrary, are constantly in a state of
composition and decomposition, the consequence of internal
movements in their structure. All is in motion. Unceas-
ingly they incorporate foreign substances or molecules with
their own, and give out to the external world particles of their
own. This vortex, or whirlpool as it were, constitutes what
is called nutrition, and is essential to life. They grow by
intussusception and not by juxtaposition, like minerals ; for
the molecules by which they increase penetrate into the in
terior of organized beings, and are there deposited.

§ 6. At length, having existed for a certain period, the

extreme limit of which is definite for each species, the living

body infallibly perishes ; mineral or unorganized bodies, on

the contrary, once formed, exist until destroyed by an external

B 2

4 ZOOLOGY.

force ; their duration is not limited ; they are not necessarily
destructible : but — I repeat — all that lives is sure to perish ;
and thus, were it not for the faculty of reproduction, not
bestowed on minerals, life under every form would soon dis-
appear from the earth.

§ 7. As regards form and size, or volume, we find that
living bodies are destined to acquire a certain size and form,
gradually and by development, which they did not possess at
birth. The form has no geometrical simplicity ; with mine-
rals it is quite otherwise. The smallest fragment of marble
is as much marble as the largest mass which can be'imagined ;
but a plant or animal can only live by attaining a certain
dimension, beyond which it cannot grow. Neither can they
be divided into fragments, like minerals, and yet exist as indi-
viduals ; a term which is chiefly applied only to organized
beings. When mutilated beyond a certain point, they cease
to exist.

§ 8. The intimate structure of living bodies furnishes other
characters. They are always composed of fluids and solids,
the former being enclosed in cells formed by plates, lamina?,
or filaments. It is this structure to which the name of
organization has been given. Nothing of the kind is to be
seen in the mineral kingdom. A spongy and areolar texture,
into which liquids may readily penetrate, is, then, a necessary
condition for the existence of life, whether animal or vege-
table ; and hence the name of organized beings, as opposed
to minerals, which receive the name of inorganic bodies.

§ 9. Lastly, the distinction between the two great divisions
of natural bodies, the organic and inorganic, extends even to
their elementary or chemical composition.

A mineral body may be formed of molecules strictly of one
kind, as sulphur or iron ; or may resultjrom the union of two
or more chemical elements, the number" of which exceeds fifty.

With living beings it is different : their chemical composi-
tion is always most complex, and in order to render this clear,
the constituent elements of such beings have been arranged
under three heads or classes. 1. Those which, like water
and various salts, present nothing peculiar, and belong to
the inorganic bodies. 2. Organic matters, such as sugar,
and urea, which are formed under the influence of life.
3. The plastic and viable products, as albumen, fibrin, cellulose,
which possess chemical characters of high importance. Into the
composition of these there always enter three — sometimes four

PEELIMINAEY IDEAS. 5

— elements, namely, carbon, hydrogen, oxygen, and azote or
nitrogen. Such bodies decompose rapidly by becoming putrid
when exposed for a certain period to moisture and warmth.
They differ also from the others in respect of their molecular
constitution, inasmuch as each atom of an organic matter
results from the union of many atoms of organized matter,
whilst an atom of a mineral body results from the union of
but a few. An atom of carbonic acid, for example, is formed
of 1 atom of carbon united to 2 atoms of oxygen ; whilst 1
atom of stearins (a kind of fat) seems to contain 140 atoms
of carbon, 134 atoms of hydrogen, and 5 atoms of oxygen.

Now these organized materials form the basis of all the
living parts of animals and plants, whilst the inorganic or
mineral play only a secondary part in the economy of these
beings. Chemically, then, these four elements characterize all
living bodies, nothing similar occurring in the mineral
kingdom.

§ 10. Thus living bodies differ from the inorganic by their
chemical composition, internal structure, general conforma-
tion, mode of origin, mode of existence, and manner of destruc-
tion. But to characterize them briefly, it is sufficient to say that
they are beings which are nourished and reproduced, these
being the most remarkable of vital phenomena. It is the pre-
sence of life, then, which especially characterizes plants and
animals, of which the simplest expression is to be nourished.

§ 11. Respecting the nature of life, science has no data :
but as in physics the cause of heat is, as it were, personified
under the name of caloric, so in physiology a special force is
admitted as the cause of phenomena wholly inexplicable by
• the ordinary laws of physics ; this is called the vital force.
Even its laws are beyond calculation, and we can only trace
some of the circumstances which seem essential to its mani-
festation. Thus, by desiccation, life is suspended in certain
animals and plants, and reappears when the requisite moisture
has been supplied. Another condition of life is, a certain
temperature and the influence of the air.

[Of late years the class of experimental physiologists have
made many efforts to reduce the whole phenomena of life to the
ordinary physical laws of matter, but as yet unsuccessfully. —
K. K.]

§ 12. Organs.— -Life manifests itself through the medium
or by means of organs or instruments, more or less numerous,

6 ZOOLOGY.

constituting the body of the animal or plant. Between the
organs and the functions they perform there is a necessary
co-relation; the muscles, for example, are the immediate
instruments or organs of motion : while the organs of sense
inform us of what surrounds us.

§ 13. Relations under ivhich Living Beings are Studied.
• — The study of the mode of conformation of the organs of an
animal or plant is called anatomy ; the study of their func-
tions, physiology. Anatomy is the science of structure ;
physiology the science of life. These sciences are mutually
dependent, and cannot be studied apart with advantage. A
knowledge of mere structure is unimportant, unless combined
with a knowledge of function.

Anatomy and physiology constitute the basis of the natural
history of organized beings ; but these must also be studied
under other relations. Hence the study of external characters,
in order to distinguish animals and plants readily and with
certainty from each other. Classification also, to aid the
memory, becomes requisite. The distribution also of animals
and plants over the globe is a matter of interest, practically
and scientifically ; while the laws regulating the distribution
merit careful study. The same remark applies to the uses
man makes of natural objects. Finally, natural history is
not occupied solely with what now exists upon the globe ; but
by the examination of fossil remains endeavours to discover
the history of those ancient inhabitants of the earth, of which
so many existed before man himself.

These varied studies naturally divide themselves into two
branches : the study of plants is called botany ; zoology
means the history of the animal kingdom.

GENERAL CHARACTERS OF.ANIMALS.

§ 14. Differences between Animals and Plants. — In the
immense majority of cases, nothing is easier than to dis-
tinguish an animal from a plant; yet occasionally this is
difficult, in consequence of the great simplicity of structure in
some animals. This uncertainty, after all, may belong rather
to the imperfection of our knowledge than to the nature of
things ; and thus it may be said generally, without dwelling
more on this subject, that animals differ from plants by cha-
racters of high importance, drawn from the nature of the
phenomena connected with their mode of life, from their

GENERAL CHARACTERS OF ANIMALS. 7

structural arrangements, and from the chemical composition
of the principal constituent matters of their bodies.

§ 15. Vegetable life seems mainly occupied with the nutri-
tion of the individual, and the reproduction of others resem-
bling it. Vegetables are inanimate, animals — animated
beings. Animals perceive, reflect, act spontaneously or by
their own will ; nothing of the kind, properly speaking,
exists in plants. Thus vegetables neither feel nor move ;
animals feel and move. Differences also exist in the manner
in which the same functions are carried on in the two classes
of beings ; these remain with more propriety to be considered
afterwards.

§ 16. The faculties of animals being more complex than
those of plants, necessitate a greater complexity of organs.
These organs differ also in their intimate structure; the tissues
in the vegetable affect a cellular or utriculose character, cells
provided with proper walls and cavities; in animals, the tissues
are composed of little plates or laminae, which intersect each
other in such a way as to circumscribe imperfect lacunae,
and thus to constitute masses or membranes, more or less
spongy, but not divided into a number of utricules or cells,
independent of each other, as in vegetables. Often, it is true,
the animal tissue whilst being developed is seen to be com-
posed of little bags (utricules) ; but this structure, which is
permanent in plants, is generally but transitory in animals,
and is persistent only in a small number of organs, as, for
example, in the glands and epidermic membranes.

§ 17. Finally, the organized matters which form the basis
of plants are composed of carbon, hydrogen, and oxygen only.
To these in animals nitrogen is added. Allowing, however,
that there exists in plants azotized matters, and in animals
compounds which are not azotized; still the organized matters
essential to the constitution of the living organs offer in the
two kingdoms the chemical composition we have just in-
dicated.

OF THE ORGANIC TISSUES OF ANIMALS, AND OF
THEIR ORGANS.

§ 18. Different elementary substances, but chiefly carbon,
hydrogen, oxygen, nitrogen, combine to produce the materials
of which animal bodies are composed. Amongst these materials
or matters, some are called organized or plastic, and form

8 ZOOLOGY.

the essential basis of all the solid parts animated by the vital
movement. These plastic materials are less varied than might
be at first supposed ; for in all animals the basis (trame) of
the living parts appears to be composed of a substance called
albumen, or of fibrin — which probably is but albumen slightly
modified. The solids also resemble each other in having
water as a constituent part, to the presence of which they,
no doubt, owe their flexibility, softness, and other physical
properties essential for the due performance of their func-
tions. But the mode of texture of the solids thus constituted
varies much, and the name of organic tissues has been
given to those parts which in their turn reunite to form the
organs.

§ 19. The principal organic tissues of animals are four :
the muscular, nervous, cellular, and utricular.

The muscular tissue forms what is commonly called the
flesli ; it is the producing agent of all motion, and is com-
posed of fibres, susceptible of contracting or of being short-
ened. These fibres, wherever placed, may always be distin-
guished by their contractile faculty, and are always found
where motion is performed.

The nervous tissue is soft, and generally whitish ; it forms
the brain and nerves ; it is the seat of sensation.

The connective or cellular tissue, also named areolar or
spongy, is, of all the constituent materials of the body, the
most abundant. In some of the more simple animals it seems
to form the whole body ; in those more highly organized it
connects and yet insulates all the organs, entering largely into
their composition, and being modified in a variety of ways, it
forms membranes and a number of other tissues ; in its sub-
stance the fat is always deposited. It is a whitish substance,
elastic, semi-transparent, composed of filaments variously
interlaced, and of small lamella?, more- or less consistent, and
irregularly united, so as to leave between them cells or
lacunae of variable size. But the walls of these cells are
incomplete, and thus permit fluids (or air) to pass freely from
one to another ; these cells are moistened with a watery and
slightly albuminous liquid, called serosity.

The utricular tissue is composed of little cells or bladders,
with distinct walls, glued to each other, either directly or by
means of an amorphous organic matter ; sometimes these
vesicles are rounded, and filled with some particular substance,
as fat, for example ; at other times they are found flattened

FUNCTIONS OF ANIMALS. 9

and dried up, so as to form lamellae, as may be seen on the
surface of the skin.

Anatomists describe other tissues as entering into the com-
position of animal bodies, such as the serous and mucous
membranes, the different varieties of the fibrous tissues, the
cartilages, the osseous tissue, &c. ; but, according to all ap-
pearance, these varied tissues are only modifications of the
utricular or connective.

§ 20. These tissues, differently combined, and affecting a
variety of forms, constitute the different organs by which the
faculties of animals are exercised. The term apparatus is
applied to an assemblage of these organs, and that of function
to the action of a single organ or of many. The apparatus of
locomotion, for example, means the assemblage of organs,
whatever they be, required for fas function of locomotion — or
motion from place to place. The structure of animals varies,
then, with their faculties and mode of life ; and generally it
may be said, that the more vaiied the functions are in any
animal the more complex will be its structure.

CLASSIFICATION OF THE FUNCTIONS OF ANIMALS.

§ 21. The functions of animals have a relation to two
objects, — namely, 1. The conservation or preservation of the
individual ; 2. The conservation of the race. Of the former,
some have reference chiefly to the support and nourishment
of the body ; others place the individual in relation to sur-
rounding objects. Hence the division of the functions into
three great classes, — those of nutrition, relation, and repro-
duction. The first and last of these collectively have been
called vegetative life : the functions of relation, physiologists
are agreed to call animal life, as being peculiarly the attri-
butes of animals] nutrition and reproduction are functions
which animals have in common with plants.

Each of these great physiological divisions is subdivided in
its turn into several others, all tending towards one end ;
thus, the nutrition of an animal is accomplished only by the
aid of several functions, such as digestion, circulation, respi-
ration, &c. : digestion, in its turn, resolves itself into masti-
cation, insalivation, deglutition, the transformation of the
food into chyme, the extraction of the chyle contained in
the chyme, the absorption of this chyle, and the expulsion
from the body of the residue of the aliment; finally, these

10 ZOOLOGY.

very acts of mastication, deglutition, &c., are all the results
of divers phenomena dependent on various organs and func-
tions.

§ 22. The utmost variety prevails in the organization of
different animals. In some, the functions are simple ; and
this implies a harmonious simplicity of the organs. In
others, complexity is the law. Between the mode of existence
and the mode of organization of each heing, there is the most
admirable accord. The proofs will be given in a future part
of this work.

The history of the functions of animals will now engage
our attention, and first, of the function of nutrition.

a

Fig. 1.

Diagram taken from the " Text Book of Physiology," by Valentin,*
intended to show that every part of an organ is a mass which is traversed by
interstices in all directions. If a liquid body presses on c, while an elastic
one is present at d, it also renders them capable of serving as a filter. — K. K.

* " A Text Book of Physiology." By Valentin. Translated by Dr.
Brinton. H. Eenshaw, Strand.

HISTOEY

PEINCIPAL FUNCTIONS OF -ANIMALS.

I.— OF THE FUNCTION OF NUTEITION.

§ 23. The nutrition of living beings consists in the intro-
duction of foreign matters into the interior of the tissues, and
the fixation, assimilation, and organization of the matters
so introduced. Every living animal is also the seat of a kind
of slow combustion, causing the unceasing destruction of a
certain quantity of organic matter. The matter thus de-
stroyed, being useless or even hurtful to the economy, is
expelled from it.

It is evident, then, that the first condition necessary for
the due performance of this molecular composition and de-
composition, is the faculty of absorption, by which the
molecules are attracted and introduced into the centre of the
tissues. It is a function common to all living beings.

§ 24. In plants, this single faculty suffices for the intro-
duction from without of all matters requisite for their
nourishment. With animals, a portion only is directly intro-
duced into the tissues ; but a great portion requires being
elaborated by a process called digestion, by which the nutrient
molecules are fitted for absorption. This faculty of digestion
forms one of the characters which best distinguish animals
from plants.

§ 25. The liquids thus absorbed spread wherever they are
required, the distribution being in some effected slowly, in a
way analogous to the absorption. In others, by far the most
numerous, the distribution of the nutrient liquids is accom-
plished rapidly by the establishment of currents, which serve
also to remove the molecules eliminated from the organs.

12 ZOOLOGY.

Thus originates another function, the circulation of the
blood, and another apparatus of organs by which this is

£• 3

performed.

§ 26. We have alluded to a kind of slow combustion which
takes place in the interior of animal bodies. This is effected
by means of the oxygen of the atmosphere which is unceas-
ingly absorbed by means of respiration ; and it is by the
same function of respiration that animals get quit of the
matters thus consumed.

§ 27. The products of the respiratory combustion, as well
as the matters eliminated from the tissues, and which, having
become as it were foreign to the economy, require to be re-
moved from it, give rise, by, this necessity, to a function the
opposite of absorption — that of excretion. The character of
this process varies according to circumstances. It is called
exhalation, when the liquids escape as it were mechanically;
secretion, when particular liquids whose nature differs from
the nourishing fluid are formed by a kind of chemical
action. By these two ways the economy elaborates the
particular juices necessary for the exercise of all the func-
tions, whilst at the same time it expels all that is useless or
injurious to it.

§ 28. The creation of the livingmatter destined to augment
the mass of the tissues or to replace the parts which have
been destroyed, is a process or work which the physiologist
ought not to confound with any of the preceding phenomena ;
it is the act by which the organism fixes in its interior a
foreign matter, organizes this matter, and develops in it
vital properties. The function is called assimilation.

Thus the functions of nutrition consist essentially of ab-
sorption, digestion, circulation, respiration, exhalation, secre-
tion, and assimilation. We shall now consider these great
acts of vegetative life.

OF ABSOEPTION.

§ 29. By absorption is meant the act or faculty by which
animals suck up and imbibe, as it were, into the mass of their
humours the substances which surround them, or which are
deposited in the interior of their bodies.

The existence of such a faculty may be very readily proved.
Plunge a frog into water, in such a way, however, that none
can enter by the mouth ; notwithstanding, the weight of the

MECHANISM OF ABSORPTION. 13

animal after a time is sensibly increased. Now this increase,
which under favourable circumstances may reach a third of
the weight of the animal, can depend only on the absorption
of water by the surface of the body.

If water be introduced into the stomach of a living dog,
and the entrance to and exit from the orgun be secured with
ligatures, still the liquid will disappear, absorbed by the walls
of the stomach, and so mingle with the blood; and yet there
exist neither in the stomach nor external integuments any
pores leading directly to the vessels containing the blood.
The pores observable on the skin lead merely to little cavities
intended to secrete various humours or to form the hairs.
Thus the tissues forming these organs (the skin and stomach)
'are permeable to liquids, and this is the case with all the
other structures of the body.

In fact, in living as well as in dead bodies, the tissues
uniformly imbibe surrounding fluids, and are traversed by
them with more or less facility.

§ 30. Mechanism of Absorption. — It is on the permea-
bility of the solid parts of animal bodies that the function of
absorption depends. The penetration of fluids into the interior
depends on a peculiar force or power acting on them. Capil-
lary attraction contributes powerfully to effect this penetra-
tion of external liquids, but it is not the only force or power
causing this phenomenon ; another was discovered a few years
ago by Dutrochet, and called by him endosmose. If, into a
little membranous sac, surmounted by a tube, water, holding
gum in solution, be poured, and the apparatus be then placed
in pure water, as in Fig. 2, the water will be found to rise in
the tube to a considerable height. Here is then an evident
absorption of water through the walls of the sac. Next
reverse the experiment, by filling the sac with pure water,
and placing the apparatus in gum-water, and the sac will
empty itself instead of absorbing more, the pure water pass-
ing through its walls in the inverse direction. ]STow this
phenomenon has the greatest analogy with what takes place
in living bodies, and partly explains it ; for the purer liquids
from without pass readily through the spongy tissues of
animal bodies, whilst the dense,- material within passes with
more difficulty in the opposite direction. Hence the accumu-
lation within, which could not take place if both passed with
equal facility, and established an equilibrium. Such an
equilibrium is prevented by the union of the purer liquid

ZOOLOGY.

with the denser liquid within the membranous sac in the one
case, and within the animal body in the other. Hence the
elevation of the gum- water in the tube, and the increase of
weight in the living animal, both being due to one cause,
namely, endosmose.

§31. Organized bodies are represented
by the sac as seen in Fig. 2. They are
placed in a surrounding medium more fluid
than that existing in their interior. Hence
they absorb.*

§ 32. Organs of Absorption. — In cer-
tain animals low in the scale of life,
absorption consists merely in the process
we have just described. In these animals
there exists no regular circulation in the
interior of their bodies ; but in the higher
classes of animals the function is more com-
plex. The fluids imbibed, as described
above, pass into the interior of the vessels,
and there mingle with the nourishing fluids
of the animal, and thus mingled and united
they pass with the blood to certain parts of
the economy, wherever, indeed, that pene-
trates. Thus the function of absorption
becomes divided as it were into two acts ;
the first, simply the act of imbibition
through the tissues; the second, that of
circulation through the interior of the animal.

§ 33. In all animals the principal agent for this trans-
portation of the matters absorbed to various parts of the
body is the blood, acted on by the heart, to which the
liquids are conveyed by the veins ; and thus it happens that
in the great majority of cases these vessels play an important
part in the function of absorption.

§ 34. In many animals there exist only sanguiferous ves-
sels, and the function is performed by them alone. In others

* The passage of liquids through various membranous coverings is a
complex subject, still open to inquiry. Thus, if spirits of turpentine be
enclosed in a glass jar, as in the setting up of anatomical preparations in
the usual way, by means of several layers of bladder, tin-foil, &e., it will in
Time escape, and, covering the exterior of the glass, obscure the object
within. If, on the other hand, only a single layer of bladder be used, none
of the turpentine will escape. This curious fact was accidentally discovered
by my brother. — K. K.

Fig. 2.

OF ABSOKPTION.

15

however, and especially the more highly organized, there
exists another order of vessels, destined to absorb certain

Fig. 3.— Thoracic Canal.*

* Thoracic cavity and upper part of the abdomen, laid open to display the
posterior wall. — 1. The thoracic duct, or canal, lying on the front of the
vertebral column, by the side of the azygos vein. — 3. Origin of this canal
from the lacteal vessels, and from the common lymphatics proceeding from
the lymphatic ganglions of the abdomen. — 4. Termination of the canal in the
left subclavian vein, near its junction with the left jugular. — 2. Large
lymphatic vessels arising on the right side of the head, and terminating in
the right subclavian and jugular veins. (Figure copied from the Traite
d'Anatomie Humaine, by M. Sappey.)

16 ZOOLOGY.

substances. These are called lymphatics, and they constitute
a system of vessels to which the name of absorbents is more
especially given.

They originate in extremely fine tubes or roots in the
animal tissues, and collecting into larger vessels, ultimately
terminate in the veins. Their walls (parietes) are extremely
fine, and they frequently communicate with each other. The
point of union is called an anastomosis. In man and in the
mammalia they exist almost everywhere throughout the body,
and they terminate at last in a single trunk, the thoracic
canal (Fig. 3), which, commencing in the abdomen, passes
through the thorax, to terminate finally in the left subclavian
vein. But others pass into veins in their course, and many
on the right side unite to form a short trunk which enters
the right subclavian vein. In their course, the lymphatics
pass through small rounded bodies, called lymphatic glands.
The use of these is altogether unknown. These so-called
glands abound in the axillae, the groins, and in the cavities of
the chest and abdomen, the neck, &c. (Fig. 35). Moreover,
in the interior of these vessels there exist numerous valves,
which permit the contents to circulate only in one direction,
that is, towards the heart.

These vessels have been proved to exist in mammals, birds,
reptiles, and fishes. In some reptiles and j)atrachia they are
even more complex than in the higher animals, having con-
nected with them contractile reservoirs, which pulsate or
contract like hearts, and may be so regarded.

§ 35. The liquid they contain is called lymph. When not
mingled with the products of digestion, it is slightly yel-
lowish, and transparent. Examined by means of the micro-
scope, spherical colourless globules are discovered in the
lymph, smaller than those found in the blood ; left to itself
it coagulates, but less strongly, like th% blood. Its composi-
tion, as 'shown by chemical analysis, is water, albumen, fibrin,
and various salts.

Little is known of the movements of the lymph in the
vessels. It ascends in the thoracic duct with considerable
force, and always in one direction.

§ 36. Absorption by means of these vessels in certain
organs may be readily demonstrated by observation on living
animals. Lay open the cavity of the abdomen in an animal
when digestion is going on, and the lacteals will be seen filled
with a milky-looking fluid, the chyle ; hence this portion of

OF DIGESTION. 17

the lymphatic system has heen called lacteal. In an animal
fasting, this fluid not being present, these vessels are colour-
less.

[The lacteals may readily be seen in an animal just dead, by
spreading out the membrane supporting the small intestine, and
looking attentively at it. When the chyle has left them, which
it does even after death, they are not so readily detected, and
may be mistaken for small veins, or vice versa. — R. K.]

Absorption by the veins may also be demonstrated in the
same way, that is, by experiments on living animals.

§ 37. Circumstances influencing Absorption. — The first
condition essential to absorption is the permeability of the
tissue interposed between the substance to be absorbed and
the liquids which form the means of transport to its destina-
tion ; so that, cateris paribus, absorption is rapid in the direct
ratio of the sponginess and softness of the tissue. It may
also be laid down as a principle, that absorption is rapid in
a direct ratio to the vascularity of the tissue. As absorp-
tion is mostly effected by the veins, the abundance of these
necessarily influences the function. Thus, anatomically, may
almost be predicated the enormous differences in the rapidity
with which various substances are absorbed by different
tissues. Of the lungs, for example, pre-eminently so spongy
and vascular, it might be predicted that absorption would in
them be most rapid ; and this is in fact the case.

The cellular tissue, forming the basis and connecting
medium of most of the organs, is also, by its soft and spong}^
nature, the seat of rapid absorption, but less so than the lungs,
as being much less vascular. .

The skin, on the other hand, being but little vascular, and
being at the same time covered by the almost impermeable
epidermis or scarf-skin, explains why we can handle dan-
gerous poisons with safety, so long as the epidermis is
unbroken.

A state of plethora (from 7r\r)6a), I fill) exercises an in-
fluence over the rapidity of absorption. The quantity of
liquids an animal body may contain is limited, and desiccation
also has its limits. The nearer the animal may be to the
point of plethora or saturation, the less will it absorb.

Thus, poison administered to two living dogs will influence
the one in a state of plethora much more slowly than the
other which has been previously reduced by a copious bleed-
c

18 ZOOLOGY.

ing ; and finally, caeteris paribus, absorption will be less rapid
as the liquids to be absorbed are less liquid and less fitted to
moisten the tissues.

OF DIGESTION.

§ 38. One of the principal means by which the absorp-
tion of the matters necessary for the nutrition of animals
is effected, is a cavity communicating with the exterior, and
into which the food is introduced.

§ 39. Aliments. — We restrict the meaning of this term,
for the sake of clearness, to those substances which, being
introduced into the stomach, are absorbed only after being
digested. It is needless to remark that food and air are
essential to the support of Ijfe.

The want of food is indicated by the painful sensation we
call hunger : its seat is in the stomach. This want and its
sensation may be diminished and kept off by rest, sleep, and
by whatever retards the vital movements. On the contrary,
it is increased by activity, fresh air, and by the use of bitters.
Hybernating animals, which sleep during winter, eat not, so
long as the lethargy continues ; and cold-blooded animals,
as fishes and frogs, can live in despite of a long- continued
abstinence. But man and other hot-blooded animals — and
more especially, for an obvious reason, the young — perish
speedily when food is withheld, even for a comparatively
short time. In Dante's celebrated episode of the destruction
of the Ugolini family by starvation, the youngest perished
first.

All alimentary substances are furnished by the organic
kingdoms — animal and vegetable ; whatever be their origin,
they may be divided into azotized elements, amylaceous or
sweet, and fatty bodies. These substances differ in their
nutrient qualities ; and it is a fact, prfrved by many curious
experiments, that a certain number of different substances is
essential for the support of life.

Thus, rabbits fed upon only one article of food, as hay,
wheat, cabbage, carrots, &c., die in about fifteen days ; whilst
fed on these articles combined or given in succession, they
live and thrive.

A hygienic law, then, is, the diversity and variety in
respect of food ; and experience and experiment agree as to
this.

OF, DIGESTION.

19

It has been proved experimentally, that substances (such
as sugar, oil, gum, fat) devoid of azote do not nourish,
however much they may be varied. The use of a certain
number of substances, such as the muscular flesh — albu-
men and the gluten found in wheat, seems essential to the
support of life.

§ 40. Digestive Apparatus. — The object of digestion is.
1st, to separate the nutrient part of the aliment from the
non-nutrient (faces); 2nd, to convert the nutrient part into
a liquid fit to mingle with the blood and thus to nourish the
body.

This elaboration of the food takes place, in animals, in a
cavity more or less ample, communicating with the exterior,
and into which the food is received, and from which the non-
nutrient ' portions are expelled. Vegetables require no such
apparatus. The cavity to which we allude is called the
digestive.

§ 41. In certain animals
the digestive cavity is simply
a pouch) having but a single
entrance by which the food
is received and the non-nu-
trient portion is expelled
(Fig. 4. a) ; and this arrange-
ment prevails in most of the
polyps, asterise or sea- stars ;
and many other animals

more complex in their struc-
tures also show this arrange-
ment. But, for the most
part, the digestive tube or
canal has two openings — an
entrance for the food, and an
exit for the non-nutrient
part, the mouth and the
amis.

The alimentary canal thus pig. 4>_
forms a tube, dilated at in-
tervals, and with two open-
ings (Fig. 5). The more important of these dilatations is
called the stomach. This cavity is sometimes single, as in
the carnivora ; sometimes quadruple, or at least complex, as
in the herbivora ; and the reason assigned for such a com-
c 2

-Hydia, or Fresh-water
Polyp.

20

ZOOLOGY.

plexity is, that vegetable food, being less easy of digestion,
requires a longer sojourn in the stomachal cavities.*

§ 42. A membrane, called mucous, lines the digestive cavity
throughout. It is analogous to the skin, with which it is
continuous, hut differs in structure. It is much softer, and
in place of an epidermis is protected on its exposed surface by
a reticular tissue, soft and turgid, called epithelium.

Maxillary Gland.
Trachea. ^ *•••,..

Liver......

Gall Bladder..^*

Colon.-...

Caecum. ,.%

Small Intestine. ..

Parotid Gland.

Pharynx.
Gullet.

Thorax.
Aorta.

-Midriff.

Stomach.

Pancreas.

Spleen.

Kidneys.

Colon.

Abdomen.

Rectum.
Bladder.

Fig. o. — Digestive Apparatus of an Ape.

Finally, it is more vascular than the other, and abounds with
secreting pores. Externally, it possesses a muscular tunic
intended to act on the contents of the tube. A serous mem-
brane, large and translucent like all serous membranes, invests

* The stomach is probably single in all animals, being simply subdivided in
some into different compartments. In whales, though strictly carnivorous
animals, the stomach is extremely complex. — K. K.

OF ABSOEPTION. 21

it externally in the abdomen, serving to fix it in its place, and
to facilitate its movements.

§ 43. The digestion of the food is effected mainly by the
action of different humours, which the food imbibes whilst
passing through the alimentary canal. These humours are
chiefly the secretions from certain bodies, called glands, situ-
ated around the digestive tube, and destined to pour into its
cavity various liquids or secretions. The number of these
secreting organs varies in different animals, but generally,
they are sufficiently numerous. The more important are the
salivary and gastric glands, the liver and the pancreas.

§ 44. Finally, to facilitate the action of the digestive juices
on the food, it is useful to divide it mechanically. To effect
this, nature employs, as is usual, various means. Sometimes
the food is compressed merely by the walls of the digestive
tube ; in other animals, as in birds and crabs, the food is
crushed to pieces in the stomach ; in others, as in man, the
mechanical division of the food is effected by means of the
teeth situated in the mouth, at the commencement of the
alimentary tube itself. These are the masticatory organs and
apparatus.

§ 45. Thus the digestive tube, extremely simple in some
animals, is in others very complex, extending from nearly
one extremity of the trunk or torso to the other. Never-
theless, its greater part is lodged in the cavity of the abdomen
(Fig. 5), which in mammals is separated from the thorax by
a muscle called the diaphragm, or midriff. Inferiorly it termi-
nates in the pelvis (Fig. 90), the interior of which possesses
a sort of muscular floor. Behind, the cavity is shut in by the
spinal column, and at the sides by broad muscles extending
from the thorax to the pelvis. Internally this cavity is in-
vested by the serous membrane called peritoneum, by portions
of which (the mesenteries) the bowels are maintained in their
place, whilst other portions, extending beyond the margins of
the stomach and bowels, and thus floating in the cavity of the
abdomen, are called epiploons and epiplooic appendages.

The various portions of the alimentary tube thus formed
and located receive different names. Its first part is called
the mouth ; the cavity following it, the pharynx ; next follows
the gullet ; then the stomach ; and this is followed by the small
intestine, itself subdivided into three portions, the duodenum,
jejunum, and ileum. After this follows the large intestine,
terminated by the anus.

22 .*• ZOOLOGY.

§ 46. Ads of the Digestive Function. — The phenomena
which take place in the different portions of the digestive tube
constitute a series of acts or functions all tending to one end.
They may be thus classed: — 1. There is the prehension of
the food ; 2. The mastication ; 3. The insalivation ; 4. The
deglutition ; 5. The chymification, or stomachal digestion ;
(). The chylification, or intestinal digestion ; 7. Defsecation ;
8. The absorption of the chyle.

Let us now examine these organs and their acts suc-
cessively, in man and in the animals which most approach
him.

Prehension of the Food.

§ 47. That this act varies in different animals is evident.
Man employs the hands and mouth. Anatomically speaking,
the term mouth includes not only the opening so-called, but
the cavity into which it leads. This cavity is very complex,
but may be briefly described as having two orifices, one
externally, on the face, the other situated deeply, and leading
to the pharynx. Its boundaries are the palate above, the

Fig. 6. — Jacchus Penicillatus, Ouistiti a piuceau, Marmoset.

tongue and floor of the mouth below ; at the sides the cheeks ;
behind, the moveable palate limits its extent, and serves the
important purpose of isolating it at times from the pharynx,
and of protecting the posterior nostrils. In man and in
many other animals the food is placed in the mouth by the
hands or anterior extremities; the lips retain it when so
placed.

PEEHENSION OF FOOD.

23

Certain animals introduce the food into the mouth by
means of a long and protractile tongue. In others, this
act is accomplished by means of a prolongation of the
nose, as in the elephant (Fig. 7) j or by means of feelers

Fig. 7.— Head of the Asiatic Elephant.

(palpi) surrounding the mouth, as in insects (Fig. 8),
whilst similar organs are called tentacula in the mollusca
(Fig. 10), the polyps (Fig. 4), Ac. ^

§ 48. The prehension of the liquid aliments or drinks
is effected in two ways. Sometimes the liquid is poured

Fig. 8. — Jaws of the
Beetle.

Fig. 9.— Carabe, a Beetle.

into the mouth, and allowed to fall into it by its own
weight; in others, it is sucked up by the mouth, either
by the dilatation of the thorax or by the action of the

24

ZOOLOGY.

tongue acting as a piston. Sucking is effected by this last
method.

Fig. 10.— The Mollusk, called Calamary ; a species of Cuttle Fish ; the
Loligo Sagittarius; very common in the Frith of Forth.

Certain of the lower animals are destined to nourish them-
selves solely by liquids found in plants or in the bodies of other

animals, on which they
live as parasites. Many
insects are thus provided
for; and their mouth,
instead of presenting the
ordinary structures, con-
stitutes a kind of tube
or a very elongated
sucker, by means of
which they draw up the
liquids they require (Fig.
11). The details of this
curious structure will be
Fig. ii.-Bomby*. Variegated buzzinR fly , explained when treating

a dipterous insect. OI the history OI insects.

MASTICATION. 25

The liquid aliment quits the mouth, and descends imme-
diately into the stomach through the pharynx and gullet.
The solid part remains for a time in order to undergo the
action of mastication.

" Mastication.

§ 49. Mastication is performed by the teeth.
The Teeth. — These organs are extremely hard substances,
resembling bone, firmly fixed into the alveolar edges of either

Fig. 12.— Lower Jaw and Teeth of the Eabbit.

jaw, and so as to act upon each other, or rather upon what-
ever is placed between them. In man, whom we select as the
example, each tooth is formed in a little membranous sac
lodged in the thickness of the jaw itself (Fig. 14). This sac,
which is named the dental capsule, is composed of two vas-
cular membranes, and encloses in its interior a small pulpy
germ or centre, similar to a granulation, into which ramify
numerous fine nerves and vessels (Fig. 13). This pulp, called
also the germ or bulb of the tooth, serves to form the tooth,
gradually becoming elongated and approaching the free edge
of the jaw, which it soon pierces, and so appears externally.
The portion thus denuded and exposed beyond the edge of the
jaw is called the corona of the tooth, whilst the portion called
root remains imbedded in the jaw like a nail driven into a
board. The osseous cavity thus lodging the tooth is called
the alveolus, and the point of union of the corona and root is
called the neck of the tooth. When the dental bulb is fixed
to the bottom of its capsule by one or more pedicles, there
arrives a moment when the hard part of the tooth deposited,
on the surface of the bulb surrounds it on all sides, compress-
ing its nourishing vessels so as to cause their obliteration.
The tooth ceases then to grow, the bulb wastes away, and a

26 ZOOLOGY.

central cavity alone indicates the place of this organ. But
when the bulb does not exhibit this arrangement ; when it is
not pedunculated, and when the tooth forms only on the upper
surface, the growth of the tooth ceases not, and no central
cavity is found in its interior.

Fig. I4.t

The large teeth found in the front of the mouth of the
rabbit (Fig. 12) offer an example of this kind of dentition :
and if their length does not constantly increase, it is because
they are worn down by trituration on their cutting edge in
proportion as they grow at the base.

§ 50. Teeth are composed of various structures. The
substance forming the greater part of the tooth, underneath,
is called the ivory or dentine. The dense covering of the
corona is called enamel: A third substance is occasionally
found towards the extremity of the roots, or even enveloping
the enamel and corona (as in the ox), to which the name of
cement or cortical substance has been given.

The ivory of the tooth is composed of an animal matter
analogous to gelatine, of phosphate of lime (in the propor-
tion of about 64 to 100 in the adult human tooth), of car-
bonate of lime (amounting nearly to T^ parts), and of a
small quantity of phosphate of magnesia. The enamel, which
differs somewhat in colour from the dentine or ivory, and
which is hard enough to strike fire with flint, shows on
analysis slight traces of an animal substance. The phosphate

* Section of a dental capsule, a, capsule ; b, bulb or germ ; c, blood-
vessels and nerves entering the germ ; d, first rudiments of the ivory of the
tooth.

. t Lower jaw of a very young infant. The outer table of the jaw has been
removed to expose the capsules of the teeth enclosed in its interior, a, the
gum ; b, lower edge of the jaw ; c, angle of the jaw; d, dental capsules ; e,
coronoid process; f, condyle of the jaw.

MASTICATION. ;

of lime in its composition amounts to -^ths. The cortical
substance or cement scarcely exists in the human teeth ; hut
in the teeth of oxen, in which it abounds, it furnishes, by
chemical analysis, 42 per 100 of organic matter, 50 per 100
of phosphate of lime, and 4 per 100 of carbonate of lime.

In the ivory of the teeth of man we discover, by means
of the microscope, a multitude offlexuous branching tubes of
extreme tenuity (called Haversian canals), which open or
terminate in the central cavity: these tubes contain calcareous
matter ; they run towards the surface of the tooth, and their
divisions terminate frequently in little cavities bearing a close
resemblance to the little cells found in the ordinary osseous
tissue. The enamel, examined under the microscope, exhibits
a multitude of fibres, or rather hexagonal prisms, in appear-
ance crystalline, closely pressed against each other, and
directed perpendicularly towards the surface of the tooth.
Finally, the cortical substance is characterized by the pre-
sence of a great number of osseous cellules, and of irregular
calciferous tubes. These tissues are not all met with in the
teeth of all animals; the enamel and cortical substance are fre-
quently absent in fishes: and occasionally the dentine, instead
of containing a single medullary cavity, contains several.
§ 51. The teeth, in some animals, instead of being

Fig. 16.— Osseous Head of the Whale,*
with the Whalebone present.

contained or fixed in the alveolar cavities (sockets), -
-unite by their base with the jawbone or maxilla,
becoming, as it were, a part of it : this happens
in many fishes, and occasionally the teeth, instead
of resembling bones, offer merely the consistence
of horn. Finally, in the whalebone whale (Fig. whale-
16) the teeth seem to be replaced by large flexible bone,
plates of whalebone (fanons, Fig. 15); and in other (Fanon^

* Mysticetus; Greenland Whale, or Whale of Commerce. Kudimentary
teeth exist in the ioetus of the whale in both jaws. — R. K.

28

ZOOLOGY.

animals, even mammals, are wholly wanting, as in the ant-
eater (Fig. 29).

§ 52. In animals which do not masticate, but merely
seize their prey with the teeth, as in crocodiles, and many
other reptiles, all the teeth resemble each other : they have

Fig. 17.— Head of the Gavial or Gangetic Crocodile.

the form of hooks or cones : but in animals which masticate,
the teeth have different forms and uses.

Fig. 18.— Mouth of Balsenoptera
Kostrata, or smaller Korqual.*

Fig. 19.— Skull of the Lion.

Thus, in man and most mammals there exist three kinds
of teeth : 1. The teeth called incisive, which have a sharp
cutting edge. 2. Conical teeth, which in many animals pro-
ject beyond the plane of the others ; these are the canine
teeth. 3. Others, called molar, whose broad and irregular
surface points out their use in the trituration of the food.

The mode of implantation of these teeth in the jaws differs,
as well as the form of the corona, being, in fact, in accordance

* The mouth of the smaller Rorqual; it has no teeth in either jaw ; the
food is caught , by the whalebone in the upper jaw. From a sketch made
from life by my former assistant, E. J. Forbes. — 11. K.

MASTICATION.

29

with their uses. The incisive, intended only to cut or divide
the food, have hut a single short root ; the canine penetrate
much more deeply into the jaws than the incisives ; and the
molar, called on to undergo still stronger pressure, are firmly
fixed hy two or three roots into the alveolar cavities.

Large Molar. Small Molar. Canine. Incisive.

Not preceded by any deciduous teeth. Preceded by deciduous teeth.

Fig. 20.— Human Teeth.

§ 53. The harmony of organization "between the teeth and
their uses is 'such, that in general it is easy, hy a sight of
the teeth of an animal, to say to what class it belongs, and to

Fig. 21.— Teeth of a Carnivorous
Animal .

Fig. 22.— Teeth of an Insectivorous
Animal.

predict much, a priori, as to its nature. Thus, in carni-
vorous animals the molars are not grinding teeth, properly so
called, hut present a sharp edge, dividing the prey like a pair
of scissors (Fig. 21) ; in insectivorous animals the teeth have

30 . ZOOLOGY.

a tuberculated surface, rough, with conical points, so arranged
as to lock into each other. In the frugivorous, living on soft
fruits (Fig. 24), these teeth are simply provided with rounded

Fig. 23.— Teeth of an Herbivorous
Animal.

Fig. 24.— Teeth of a Fru-
givorous Animal.

tubercles ; in the herbivorous these teeth have a broad, rough
surface, resembling a millstone (Fig. 23).

ftp!

Fig. 25.— Skull of the Narwhal.*
Lower surface.

Fig. 26.— Skull of the Narwhal.

Upper surface.
Upper cervical vertebrae.

* This and the two following figures illustrate the singular fact of the
development of only one of the incisives in the upper jaw ; the other remains
imbedded in the osseous tissue of the maxilla. The figures also show the re-
markable want of symmetry in the cranium of certain of the cetacea. — K. K.

MASTICATION. 31

[The law based on a harmony of organization between the
teeth and their uses and between the teeth and other organs of
the body must be used with great caution. A universal law of
organic harmonies no doubt exists, but its true nature has not
yet been discovered. Cuvier, who boasted so much of this law,
nevertheless used it with the utmost caution, and never trusted
wholly to it.— K. KJ

Fig. 27.— Skull of the young Narwhal, before the development of the
left incisive, which sailors call its horn*

Of all the teeth the molars are the most useful : hence their
presence is much more frequent than the incisives or ca-
nines. These latter, for an obvious reason, are never wanting
in the carnivora; but they are not unfrequently absent in the
herbivora.

[The reason is not at all obvious, even where it is the case ;
such teeth are wanting in the strictly carnivorous cetacea. —
K. K.]

The canine in some animals grow to a large size, and
become instruments of attack and defence (Fig. 28).

§ 54. At birth it is seldom that the human teeth have cut
the gums ; they appear usually from six months to a year
after birth. The teeth which first appear are called milk
teeth, or deciduous, as destined to be thrown off and to be
replaced by others. They are twenty in number, namely, in
each jaw ten — viz., four incisives, one canine, and two molar.

32 , ZOOLOGY.

About seven years of age these begin to fall or to be
thrown off, and to be replaced by another series of teeth,
situated in capsules imbedded more deeply in the jaws ; their
roots therefore are longer, and their insertion firmer.

Fig. 29.— Head of the ant-eater.
Myrmecophaga Jubata.

Fig. 28.— Head of the Boar.

The. teeth of the second dentition are more numerous than
those of the first : they are thirty-two in number, sixteen in
each jaw ; namely, four incisives, two canine, four small or
false molar, having each two roots, three true molars situated
behind these, and having each three roots (Fig. 20).

In old age these permanent teeth fall as did the deciduous,
but they are not replaced.

§ 55. Mechanism of Mastication. — The teeth, the pas-
sive instruments of mastication, are put in action by the
muscles of mastication acting on the jaws. The upper jaw,
forming a fixed portion of the head in mammals, moves only
with the head ; but the lower, by means of its articulations,
acts readily and powerfully, and by means of many muscles,
and with the aid of the tongue and cheeks, forces the food in
such a way between the surface of the grinding teeth as to
expose it fully to their action.

§ 56. This operation is an important one, inasmuch as the
more the food is masticated the easier will be the digestion.
When such instruments are wanting in> animals whose food
still requires trituration, this is effected by other means. The
gizzard, for example, in many birds is sufficiently strong to
answer this purpose.

Insalivation.

§ 57. Whilst the food is undergoing trituration in the
mouth, it imbibes saliva, which sometimes even dissolves it.

§ 58. The saliva is formed partly in little mucous cavities
hollowed out of the mucous membrane of the mouth, partly

MASTICATION. 33

by glands situated around this cavity, and communicating
with it. These glands are composed of small granulations,
agglomerated. In man there exist three salivary glands on
each side, placed around the lower jaw; the parotid, the sub-
maxillary, and the sublingual. They have each an excretory
duct, by which their secretions are poured into the mouth in

From Valentin.*

variable quantities. The follicles of the mucous membrane of
the mouth are disseminated partly over the surface of the
tongue and cheeks, and partly collected into two groups,
situated in the isthmus or passage by which the mouth com-
municates with the pharynx. These little masses of follicles
are called amygdalae, or tonsils.

The mixed saliva coming from these various sources is
composed of 993 parts of water to 1000 of saliva. In addi-

* In the act of mastication the lower jaw (a, i) is pressed against the im-
movable upper one (k, g). Since the upper and lower rows of teeth are
arranged symmetrically, it is only the corresponding masticatory surfaces of
opposed teeth which work upon each other.
D

34 ZOOLOGY.

tion, there exist a peculiar principle called ptyaline and
animal diastase, various salts, as sea salt or chloride of
sodium, tartrate of soda, and a little uncombined soda, ren-
dering the saliva alkaline.

The saliva thus mixed with the food facilitates mastica-
tion, assists in deglutition, and obviously aids in the digestion
of some kinds of food.

Deglutition.

§ 59. In mammals, between the buccal cavity and the
pharynx, is a moveable muscular partition, the pendulous
palate (Fig. 31), which, during mastication, separates the
two cavities from each other ; but so soon as this is accom-
plished, the alimentary mass or bolus being pressed back-
wards by the tongue, the pendulous palate is drawn upwards

Pendulous Palate.

.___ yNose.

Base of the Cranium. , """

t
Pharynx. Jf^jf^JjjKJ^^^^^^ Tongue.

Salivary Glands.
Lingual Bone.

Larynx.

Thyroid Gland.

Trachea or Wind-
(Esophagus.

Fig. 31.— Vertical Section of the Mouth and Throat in Man.

and backwards, so as to permit of the passage of the food
or drink through the isthmus into the pharynx. At this
point deglutition commences, the term being applied to the

DEGLUTITION. 35

passage of the food and drink from the pharynx, by the gullet,
into the stomach.

§ 60. The pharynx (Fig. 31) is the cavity immediately fol-
lowing the mouth, and communicating with it hy the isthmus.
It receives the food from the mouth, and the air passes hy the
same passage when the nostrils are closed or obstructed.
Seven openings lead to or from this cavity, the posterior nos-
trils, namely, being two; the Eustachian tubes leading to the
ears, two ; the opening to the mouth, one ; the opening of the
v gullet, one ; the aperture leading to the lungs through the
larynx and windpipe, one ; seven in all. The trachea is the
tube leading into the chest, surmounted by the larynx. By
this tube the air passes into the lungs, placed in the thorax,
and the oesophagus or gullet passes through the chest and
enters the abdomen to expand, as it were, into the stomach.
By this tube the food and drink pass into that organ.

§ 61. Whilst the alimentary bolus is passing from the
mouth to the pharynx, the apertures of the posterior nostrils
are protected by the pendulous palate ; the tubes leading to
the ears by a peculiar mechanism, and by their direction ;
the opening leading to the larynx and air passage or trachea
Is protected by a cartilage of a singularly wonderful mecha-
nism, closing the air tube hermetically whilst the food is
passing over its upper surface; the gullet is then the only
aperture left by which the food can escape from the pharynx,
and this leads directly to the stomach. The movements and
cou tractions required to effect these actions are numerous,
•complex, and quite involuntary; when disturbed, the food
may penetrate into the larynx and windpipe, causing for an
instant terrible distress, and certain death if not speedily
relieved. Finally, the gullet being in part muscular, by its
•contractions the food is readily propelled into the stomach.
It is almost needless to say that the gullet is nearly straight,
and that the food does not descend into the stomach by its
own grarity.

Stomachal Digestion or Chy unification.

§ 62. The food is changed in the stomach into the sub-
stance called Chyme. The stomach (Fig. 32), is a mem-
branous bag placed transversely in the upper part of the
abdominal cavity, and almost immediataly below the dia-
phragm ; in man it has the shape of a bagpipe, and indeed it
is with the stomachs of animals having this shape that the

D2

36

air reservoir of the bagpipe is made. It diminishes gradually
from left to right, and is curved on itself, so that its upper
edge is short and concave, its inferior, called the greater cur-
vature of the stomach, convex and long. By an opening
called cardiac (or, hetter, oesophageal), it communicates with
the gullet; the opening leading into the small intestine is

Liver. Pylorus. Gullet. Pancreas. Stomach.

Gall Bladder.

Large
Intestine.

Caecum. —

Appendix of

the Cajcum.

x Spleen.

---Colon.

_. Small
Intestine.

"Colon.

Small Intestine. Rectum.

Fig. 32. — Digestive Apparatus in Man.

called pyloric. The walls of the stomach are very dilat-
able : when empty, a number of folds may be seen internally,
which disappear when the stomach is full. Little follicles
or cavit'es may be seen also. The term pylorus is derived

DIGESTION. 37

from the Greek word TrvXovpbs, a porter (nvXr), a gate, and
ovpbs, guardian). During digestion in the stomach, the
pyloric orifice is closed, and afterwards, opens to allow of the
passage of the chyme into the intestine ; over the interior of
the stomach are numerous small cavities called gastric fol-
licles, which pour out upon the food the liquid they secrete.

This liquid is the gastric juice, the most important of all
the agents of digestion, for by it the food is converted into
chyme. So long as the stomach is empty, it is secreted
only in small quantities ; but in the organ filled with food,
especially if solid, the gastric juice is secreted in abundance.
Its acid properties are always well marked.

§ 63. The alimentary substances which accumulate in the
stomach being pressed on by the muscular wall of the stomach

Fig. 33. — Stomach of the Porpoise.*

and abdomen would reascend the gullet, but are prevented by
the contraction of this organ. This resistance, however, is
frequently overcome, as in regurgitation and vomiting. On
the other hand, the contraction of the pylorus during diges-
tion retains the food for some time in the stomach.

§ 64. The food thus retained is collected chiefly in the
part called the great cul de sac of the stomach. Some

See "Transactions of the Koyal Society of Edinburgh." The Memoir

Cuvier for muscular fibres. — 11. K.

38 ZOOLOGY.

of its contents, as water, alcoholic liquids, &c., are taken
up or absorbed by the walls of the stomach, and thus enter
the blood without further change. Others pass the pylorus
unaltered, and escape with the fseces; but the greater part
undergoes the action of digestion, and is by this transformed
into a pulpy semi- liquid mass, called chyme.

It would appear that the alimentary fragments placed on
the surface of the mass, and more immediately in contact
with the walls of the stomach, imbibe the gastric juice, be-
come acid, and soften from the circumference towards the
centre. With time the whole mass undergoes this change,
and becomes converted finally into a soft pultaceous greyish
mass, of a faint and peculiar odour : this is the chyme, mingled
with the debris of the food.

§ 65. Nature of the Digestive Process. — Prior to the
experiments of Spallanzani, the true nature of the digestive
process was not understood. He it was who first showed,
by direct experiment, that the solution of the food in the
living stomach was due to the action of the gastric juice;
and this he proved, by enclosing the food in tubes of wood,
perforated so as to allow of the action of the secreted liquids,
but strong enough to resist the action of the walls of the
stomach : thus proving that trituration was not the cause of
digestion. He carried his experiments still further, for by
withdrawing, by means of little bits of sponge secured with
threads, a sufficient quantity of the gastric juice from the
stomachs of crows and other birds, he imitated successfully
the digestive process on food placed in close vessels, heated
to a proper temperature.

It is evident, then, that the gastric juice is the true solvent
of the food in the stomach, and a question arises, namely, to
what property it owes its active power.

§ 66. Ascribed hitherto to the presence of the hydro-
chloric and lactic acids which always enter into its composi-
tion, the experiments of Eberle, Schwan, and Muller seem to
prove the existence of a peculiar principle (pepsin) analogous
to the action of diastase on tinder. But this substance or
principle requires to be combined with an acid, the hydro-
chloric or acetic for example. It can then dissolve fibrin,
coagulated albumen, and the greater number of the solid
alimentary bodies ; and it further produces important changes
in the chemical nature of some of these bodies, as for ex-
ample, in albumen.

CHYLIFICATION. 39

Certain alimentary substances, as fecula and gluten, are
not acted on by pepsin ; and in order to be digested they
require to be previously submitted to other agents. The
saliva is one of these agents ; and thus it is that in herbivorous
animals there often exists, between the mouth and stomach
properly so-called, a first cavity, intended to lodge the food
whilst being mixed with the saliva. In the mammals
called ruminants, this pouch, or first stomach as it has been
called, is named the paunch (Fig. 34) ; and in birds, the
jabot or crop.

Gullet,

Cardia. -
Third Stomach.

Intestine.

Pylorus. St. p. d. 2nd Stomach. Paunch.
Fig. 34.— Stomach of the Sheep.

Fatty substances used as food resist the action of these
juices, and pass the stomach unaltered. It is only in the
intestines that they meet an agent equal to their solution.

Whilst chymification proceeds, the muscular fibres act
circularly, and push the mass, at first from right to left,
afterwards from left to right, towards the pylorus, by which
the chyme passes on to the small intestine. This action is
called peristaltic.

Chylification.

§ 67. Intestines. — The portion of the alimentary canal
immediately following the stomach is called the intestine,
(Fig. 32.) This membranous tube, variable in its capacity,
is in man about seven times the length of the body. In

40 ZOOLOGY.

the purely carnivorous animals it is shorter, and in the
strictly herbivorous, longer than in man, who is generally
considered to be omnivorous. Thus, in the lion, it is only
thrice the length of the body, whilst in the ram it measures
twenty- seven times the length of the animal. The reason
assigned is the facility, on the one hand, with which animal
substances are digested, and the comparative slowness with
which vegetable substances undergo this change.

Lodged in the abdomen, the intestines are enveloped and
supported by a membrane called the peritoneum ; they are
further subdivided into the small and large intestines, and
these names are preserved, though occasionally inapplicable
to the organs described.

The small intestine follows the stomach immediately, and
it is in it that the digestion is completed. It forms about
three-fourths of the entire length of the tract of the intestines.
The smoothness of its external surface is due to its peritoneal
covering ; internally, its mucous membrane presents on its
surface a number of villosities and of small follicles. Many
transverse folds exist, projecting into the interior of the tube:
they are supposed to assist in retarding the progress of the
alimentary mass, and thus effecting a more complete absorp-
tion of the chyle. The villosities are considered as the means
by which this absorption is effected.

Anatomists divide the small intestine into duodenum,
jejunum, ileum — a division of but little importance in phy-
siology.

§ 68. Liver and Pancreas. — The alimentary matters
which have passed into the small intestine mingle with the
fluids secreted by its walls and with two peculiar liquids
secreted by the liver and pancreas (the bile and the pancreatic
juice), two glandular organs situated in the immediate neigh-
bourhood of the intestine.

The liver (Fig. 32), the organ which secretes the bile, is
the largest viscus in the body. It is situated in the upper
part of the abdomen, mostly on the right side, and extends as
far as the lower edge of the ribs. Its upper surface is convex,
the lower concave and irregular ; its colour red-brown ; its
substance soft, yet compact; and when torn it appears to
be formed of an agglomeration of small solid granulations, in
which bloodvessels abound and from which arise the excre-
tory canals of the bile.

These excretory canals unite so as to form smaller and

CHYLIFICATION. 41

larger trunks successively, until they terminate in a single
trunk, which, after a certain course, terminates in the duo-
denum a short way from the pyloric orifice of the stomach.
The hepatic tube thus described communicates by a short
tube with the gall-bladder, which is maintained full of bile
by means of the cystic duct.

In the lower animals the liver is often replaced by an
agglomeration of small tubes terminating in cul de sacs, and
inserted by their open mouths into the branches of an excre-
tory canal (as in the crabs and lobsters), or by simple but
long vessels, as in insects. Finally, in beings of a very simple
organization, the liver is either wanting or replaced by a
glandular tissue surrounding a portion of the intestine;
nevertheless, it is one of the organs found most constantly to
exist in the animal kingdom.

§ 69. The bile is a viscous liquid, greenish in colour,
thready, and extremely bitter. It is always alkaline, and has
a strong analogy with soap.

Chemical analysis shows it to be composed of a salt formed
of soda united to a fatty acid of a peculiar nature, cholesterine,
a colouring principle, a little of the oleate or margarate of
soda, mucus, and water. But the bile has other uses, fur-
nishing peculiar substances to the blood.

§ 70. The pancreatic juice strongly resembles saliva,
physically and chemically ; but, in addition, it rapidly unites
into an emulsion with fatty bodies ; the pancreatic gland,*
which forms it, resembles the salivary glands in structure.
In man it is a granular mass, divided into a great num-
ber of lobes and lobules, firm in consistence, and of a greyish
colour, slightly reddish, situated transversely between the
stomach and vertebral column (Fig. 32). From each of the
granulations there arises a fine duct, and all these reunite to
form a canal which opens into the duodenum close to the
entrance of the bile duct.

§ 71. Formation of the Chyle. — The chyme formed in
the stomach enters the intestine by the pyloric orifice of this
viscus, and passes through the intestine by its peristaltic
motion. During this passage it mingles with the bile, pan-
creatic juice, and other secretions from the mucous mem-
brane of the intestine, and gradually changes its properties ;
it becomes bitter, yellowish, less and less acid, then alkaline ;

* From nav, all, and /cpe'as, flesh*

42 ZOOLOGY.

the amylaceous and fatty bodies which had resisted the action
of the gastric juice are now acted on by the bile and pancreatic
juice ; and various gases are disengaged from the alimentary
mass distending the intestine. These gases are chiefly car-
bonic acid gas and hydrogen ; sometimes nitrogen. Finally,
the more fluid parts of the chymous mass are absorbed by the
lacteals, which become rarer and rarer towards the lower
portion of the small intestine, until they are no longer to be
found, and the mass formed by the remains of the chyme, by
the bile, and other humours already mentioned, acquires in
this portion of the tube more consistence, assumes a brown
colour, and thus passes into the large intestine.

Expulsion of the Residue left after Digestion.

§ 72. The alimentary matters which do not admit of
digestion require to be expelled from the body. For this
purpose they are collected into the large intestine.

The Large Intestine (Fig. 32) is continuous with the
small, and in most mammals is easily distinguished from it
by its irregular cellular aspect. Anatomists divide it into
caecum, colon, and rectum. The caecum,* situated in the
right iliac region, is prolonged into a cul de sac, beyond the
point of insertion of the small intestine. At its lower ex-
tremity it communicates with a small tube, the appendix
vermiformis, which may be considered as a prolongation of
the caecum. A very perfect valve, formed of folds, and
situated internally at the junction of the small intestine
with the large, is placed so as to prevent or impede the
return of whatever has passed from the small into the larger
bowel.

The colon is a continuation of the caecum. It traverses
the abdomen immediately beneath the stomach, gains the
left side, and, descending to the edge of the pelvis, is con-
tinuous with the rectum. This latter terminates at the
anus.

§ 73. The residue of the food passing from the caecum
and colon to the rectum, remains there for a certain time.
The matter has now acquired considerable consistence and a
peculiar odour. Gases are developed which differ from those

* The ceecum (cacus, blind) forms a cul de sac at the commencement of the
large intestine.

ABSORPTION OF PRODUCTS AFTER DIGESTION. 43

generated in the small intestine; they are the carbonated
hydrogen, and a little sulphuretted hydrogen.

Fleshy fibres, forming a sphincter, constantly in action,
surround the aperture of the bowel, and thus prevent the
escape of its contents, until the moment arrives for its evacua-
tion. This is effected mainly by the muscular action of the
bowel itself, assisted occasionally by the diaphragm and
levatores ani muscles.

§ 74. Theory of Digestion. — The object of digestion is to
fit the food for absorption by the lacteals. A portion of the
alimentary mass being soluble in water, is of consequence
directly dissolved by the saliva, the gastric juice, and the
water swallowed as part of our food, without the intervention
of any special active principle. The animal diastase con-
tained in the saliva possesses the property of transforming
fecula into glucose, and thus determines the solubility of a
portion of the amylaceous matters introduced into the stomach.
The pepsin contained in the gastric juice acts in an analogous
manner upon the fibrin, albumen, &c., and liquefies these sub-
stances in the cavity of the stomach. The fecula which may
have resisted the action of these agents, and has reached the
intestine untouched, there meets with the pancreatic fluid,
whose action is analogous to that of the salivary secretions,
and thus the solution of the amylaceous portions of the food
is completed. Finally, the fatty matters, which also have
escaped the action of the saliva and gastric juice, are formed
into emulsions by the action of the pancreatic secretion, and
sometimes by the aid of the alkali contained in the bile; and
just as these various solutions go on, the product is taken up
by the absorbents in connexion with the walls of the stomach
and intestine. Certain of the substances thus dissolved under-
go modifications in their chemical nature. Thus the sugar of
the sugar-cane is changed into glucose ; but the most impor-
tant and most general of the phenomena connected with
digestion is the liquefaction of the alimentary matters.

Absorption of the Products of Digestion.

§ 75. The nutritive matter thus extracted from the ali-
ment has now to pass into the mass of blood, which fluid it
is destined to renovate.

Some of the liquids and soluble matters introduced into
the stomach and intestine are absorbed directly by the veins

44

ZOOLOGY.

which abound in the walls of these organs ; but the greater
part of the fibrin and fatty matters which form the chyle
follows another route, and penetrates another system of vessels,
by which it reaches the veins, but in an indirect way. These
vessels, called indifferently lacteals,^ or chyliferous vessels,
form a portion of the absorbent or lymphatic system of
vessels. (See § 34.) They originate in the villosities of the
mucous membrane of the small intestine, and unite into
branches or single vessels, which are placed between the two

Aorta. Thoracic Canal. Lymphatic Ganglions.

{Kadicles of the
chyliferous
vessels.
Intestine.

Lymphatic Vessels. Mesentery.

Fig. 35.— Chyliferous Vessels.

folds of the mesentery. In their course towards the thoracic
duct, these lacteals pass through the ganglions called mesen-
teric (Fig. 35). Again assuming the form of single vessels
on emerging from these ganglions, they proceed to the thoracic
duct, in which they terminate. By means of this duct, the

* From the milk-like appearance of the chyle which they contain. The
lacteals proceeding from the intestine to the lymphatic glands or ganglions
are called vasa afferentia, and those from the glands to the thoracic duct
Txisa ejferentia.

OF THE BLOOD. 45

chyle thus formed is conveyed into the left subclavian vein
(Fig. 3).

§ 76. When an animal has been kept without food for
some time, these vessels are nearly empty ; but when diges-
tion is going on rapidly they become filled with chyle, the
colour of which is white, like milk ; and hence the name of
lacteals given to them by their discoverers.

The absorption of the chyle seems to take place chiefly by
means of the villosities ; for so soon as this phenomenon com-
mences, they become swollen, like sponges filled with milk by
imbibition. From these the chyle passes into the lymphatic
(lacteal) vessels, by a process as yet unknown ; and after
traversing the mesenteric glands, proceeds by other lacteals
from these glands to the thoracic duct. The cause of this
iipward and onward movement of the chyle towards the
veins is not well known.

§ 77. Chyle. — This liquid varies in appearance according
to the animal and the kind of food which has been used. In
man and in most mammals it is of a milky- white colour, of a
peculiar odour and brinish alkaline taste. Examined by the
microscope, it seems composed of a serous liquid, holding in
suspension fatty drops and circular globules. Chyle formed
from food not including fatty matters is much less opaque
than that having in its composition oil and fat. In birds,
the chyle is almost always transparent.

Taken from the lacteals near their origin in the intestines,
the chyle is found to be composed mostly of albuminous
matters; but examined in the thoracic duct, near its junction
with the subclavian vein, it is found to contain fibrin, in-
creasing in quantity the nearer to its passage into the venous
blood. On the presence of this substance depends its property
of spontaneous coagulation, like the blood. It now becomes
of a light rose-colour, and reddens slightly on exposure to
the air. In brief, it more and more resembles the blood, with
which it finally mingles in the left subclavian vein.

We have traced the elaborated nutritive matter to the
blood. This fluid must now engage our attention, also the
manner in which it is distributed to all parts of the body.

OF THE BLOOD.

§ 78. In animals of the simplest structure, all the liquids
of the animal economy resemble each other. It seems, in-

46 ZOOLOGY.

deed, to be only water charged with a certain amount of
organic particles; hut in animals higher in the scale of heing,
the humours cease to he of the same nature, and there is one,
distinct from all the others, destined to nourish the body :
this fluid is the blood. It not only nourishes the body, but
is the source whence are drawn all the secretions, such as the
saliva, urine, bile, and tears.

§ 79. In mammals, birds, reptiles, fishes, and in most
animals of the class annelides, the blood is red. But in the
greater number of the lower animals the blood presents
various hues and density, being often thin or watery, and
slightly yellow or green, rose-coloured or lilac. It is diffi-
cult, therefore, to be seen, and for a long time these animals
were called bloodless or exsanguineous.

Those animals with white blood are very numerous ;
all insects, for example.5* The Crustacea of all sorts have
only white or pale-coloured blood; and in this category
may be placed all the mollusca, zoophytes, and intestinal
worms.

§ 80. By the use of the microscope we discover that the
blood of a red-blooded animal is composed of a yellowish
transparent liquid, called serum, and of a number of small
solid corpuscles which float in the serum, called blood glo-
bules.

§ 81. Globules of the Blood. — Before birth, the globules
have dimensions and even a form different from what they
afterwards acquire. Thus in the chick the globules of the
blood are at first circular ; and it is only at a more advanced
period of incubation that the globules assume an elliptic
form. After birth the globules never vary.

In all animals of the same species the globules have the
same form and nearly the same dimensions. It is not so
with different species. It has been observed also that in
animals of the same class the blood globules resemble each
other, but differ from those of other classes. In the first,
they have nearly all the same form; but in those of a diffe-
rent class, they may vary not only in dimensions but even in
form.

Thus, in man (Fig. 36) and in most mammals the
globules of the blood are circular. In the camel and lama,

* The red-coloured liquid which appears when the head of these insects is
crushed is not blood, but comes from the eyes.

OF THE BLOOD.

47

however, they are elliptic. In birds, reptiles, batrachia, and
fishes, they are elliptic (Fig. 37.)

The corpuscles are always microscopic; and in (g)
man, and in mammals generally, they are extremely (^ *=*
small. In man, the dog, rabbit, and some others, \3J ^
their diameter is from the three-thousandth to the -p. 36 *
four-thousandth part of an inch.

In birds, the globules are larger than in mammals. In
the reptiles and batrachia they are still larger. In the proteus
they attain their maximum.

Finally, in fishes, the blood globules ^ £

are intermediate between those of birds
and the batrachia.

Moreover, the blood globules are
always flattened, and present a central
spot or nucleus, surrounded with a rim
or border. Their structure is extremely
difficult to be clearly made out ; but
when seen to most advantage, they seem
to be composed of a central nucleus and
an envelope resembling a bladder. This
envelope being depressed, gives to the
globule the appearance of a disc swollen
in the middle. It is of a reddish colour,
and seems formed of a substance re-
sembling jelly, but very elastic. The central nucleus is of a
spheroidal form, and is not coloured. In mammals the
nucleus is not distinct, and the central portion is depressed ;
but analogy induces us to suppose that, as in other animals,
it is also present in man.

Other globules, spherical and colourless, exist in the blood,
resembling greatly those observed in the chyle ; from being
mingled with the red globules they are not readily ob-
served.

§ 82. In the white blood of the invertebrate kingdom,
globules are also found, but different from those described ;
the size varies much in the same individual, and their surface
has a raspberry appearance; their form is generally spherical,

* Globules of the human blood, magnified nearly 400 times (in diameter).

f Elliptic globules of the blood in birds, batrachia, and fishes ; — a,
globules of the blood in the domestic fowl, seen in profile; — b, globules
of the blood in the frog; — c, globules of the blood in a fish of the shark kind
(equally magnified) .

Fig. 37.f

48 ZOOLOGY.

but neither a central nucleus nor external envelope is to
be seen.

§ 83. Composition of the Blood. — The composition of the
blood is very complex. In the higher animals we find water,
albumen, fibrin, a colouring matter containing iron, a yellow
colouring matter, several fatty substances, as cholesterine,
cerebrine (a substance containing phosphorus) ; many salts,
as chloride of sodium or sea salt, sulphate of potass,
carbonate of soda, hydrochlorate of potass, hydrochlorate of
ammonia, the carbonates of lime and magnesia, with phos-
phates of soda, lime, and magnesia ; the lactates of soda, the
alkaline salts formed by the fatty acids; finally, free carbonic
acid, nitrogen, and oxygen. But this complexity, great though
it be, is yet below the reality, for there certainly exist other
substances in the blood which chemistry cannot demonstrate,
by reason, probably, of our imperfect means of analysis. By
arresting, for example, the secretion of the urine from the
blood, various matters will then be found mixed with the
blood which could not be previously detected, but which are
presumed to have been present under the same or other un-
known forms.

The substances enumerated as entering into the compo-
sition of the blood compose nearly all the parts of the animal
economy : the albumen forms the basis of many tissues, the
fibrin is the constituent part of the muscles, and the salts
enter into the composition of the bones and of many hu-
mours ; and from the whole of the facts known, it may be
safely concluded that the materials destined to become flesh,
bile, urine, &c., already exist in the blood, the organs which
are to appropriate them merely drawing them from the blood,
but not forming them : and thus there exists some reason
for calling the blood liquid flesh.

§.84. The proportions in which these constituent parts
of the blood exist vary much in different animals; and
as regards the solid and liquid elements, they may differ
in the same individual at different times. In man the
globules arc more numerous, and the watery part less
than in woman; temperament also exercises some influence
in this respect. In 100 parts of the blood in man, we find
79 parts of water, 19 of albumen, 1 part of salts, with
some traces only of fibrin and colouring matter. In birds,
the proportion of water in the blood is less; but in the
batrachia and in fishes the amount is greater. In the

OF THE BLOOD. 49

frog, for example, there are 88 parts of water in 100 of the
blood.

Analogous differences are observed in comparing the relative
qualities of the serum and globules of the blood in different
animals; while — as we shall subsequently see — there exists a
remarkable relation between the amount of the globules and
the animal heat. Birds, of all animals, have the blood richest
in red "globules, and in them the animal heat is greatest.
Mammals, less warm than birds, have from 7 to 12 per cent.,
whilst in reptiles and fishes, the proportion does not exceed
5 or 6 per cent, of the whole weight of the blood.

§ 85. Coagulation of the Blood. — In its ordinary con-
dition the blood is always fluid: withdrawn from the vessels
of the living animal, and left for a time to itself, it sepa-
rates into two portions, a semi-solid mass and a liquid
portion, in which the mass floats ; the solid part is called the
dot.

This phenomenon (the formation of the clot) is due to the
presence of fibrin in the blood ; it is held in solution in the
serum during life, but when this loses its influence over it,
it solidifies, inclosing with it the red globules, and thus forming
the red gelatinous mass called the clot. The simple experi-
ment of beating up the blood with little rods as it flows from
the veins, and thus removing the fibrin, which adheres to
the rods, proves that the coagulability of the blood depends
on the presence of this substance.

Another experiment equally simple shows that the fibrin is
contained in the serum, and not in the red globules, as -was
long supposed. Throw on a filter the blood of a frog ; all
the serum may be made to pass, and the globules retained ;
in the serum thus separated from the globules a clot is
formed, which, however, is colourless.

§ 86. Use of the Blood. — The blood is the special agent
of nutrition, and the general restorer of what is lost.

§ 87. But in addition, it is proved, by the simple experi-
ments of bloodletting and of transfusion, to form an essential
stimulus for the performance of the functions of life. By
severe bloodletting or loss of blood we become enfeebled and
seemingly dead ; but if, before this happens, the blood of
another animal be transfused into the veins of the suffering
individual, the vitality is restored. The importance of the
globules is also proved by the same experiment, for if simple
serum be so transfused, death takes place.

50 ZOOLOGY.

The fibrin of the blood also plays an important part, for
M. Magendie has shown that when blood deprived of its
fibrin is injected into the veins of a dog, the animal dies with
symptoms resembling those of putrid fevers.

§ 88. The influence of the blood over nutrition may also
be readily demonstrated. Withdraw the blood more or less
from any organ, and it gradually wastes away in proportion
to the quantity withdrawn; on the contrary, the greater
size of the muscles in those who employ them actively,
and hence draw to them a larger amount of blood, is well
known.

§ 89. The blood, by thus acting on the organs, loses its
nourishing properties. It reaches them of a bright vermilion
colour ; as it leaves them it is dark and sombre-coloured, and
has lost its qualities of maintaining life. But the blood thus
altered has its vital properties restored by being exposed to
the atmosphere. This important function is called Respira-
tion. The blood which has been exposed to the air is called
arterial : that which has already acted on the organs is
called venous ; the latter is chiefly distinguished by its dark
colour.

CIRCULATION OF THE BLOOD.

§ 90. The circulation of the blood in man and mammals
was discovered by Harvey in 1619.

In order to nourish all the parts of the body, it is neces-
sary that the blocd should be conveyed to these parts by
means of vessels; and that, to circulate in these vessels, there
should be a power or organ equal to the production of such a
movement. But it is also necessary, in the higher animals,
that the blood should be passed through the respiratory
organs, in order to be exposed to the action of the air ; hence
the necessity of a circulation of the blood through the lungs,
as well as through the body, and hence both a pulmonary
and a systemic circulation.

§ 91. Apparatus of the Circulation. — In certain of the
lower animals, the air penetrates into the tissues through
pores situated on the surface of the body ; but in all the
higher animals, and in many of the lower, there exists a very
complex apparatus for the circulation of the blood : 1. A
system of tubes or canals, destined to convey the blood into
the various parts of the body. 2. An organ destined to put

CIBCULATION OF THE BLOOD.

51

this fluid in motion. In other words, bloodvessels and a
heart.

The heart is the centre of the circulatory apparatus : it is
a pouch or bag, more or less complex, into which the hlood is
returned by the veins, and from which it passes to the body,
thus constantly circulating. It is, in fact, a forcing-pump
placed at the centre of the circulatory system.

Most animals, from man to the spider, have a heart ; but
the arrangement differs in the various classes of animals.

The bloodvessels are of two kinds : 1. Arteries, which
convey the aerated blood into the various parts of the body.
2. Veins, which re-convey the blood to the heart from the
body. The arteries, proceeding from the heart, divide and
subdivide in their course as they proceed, until they become
exceedingly small : the veins follow a different course ; they
commence by extremely fine roots, and collect into large
branches and trunks as they proceed towards the heart, in
the arteries, the motion of the blood is from the heart ; and
in the' veins, towards the heart. The arteries terminate, and
the veins commence, in a fine network of vessels formed by
both; the vessels composing this net-
work are called capillary. The heart
being thus placed between the termina-
tion of the veins and the commencement
'of the arteries, the movement of the
blood in man and higher animals is a
complete circle, the blood always return-
ing to the point from which it started ;
hence it has been called the circulation
of the blood.

In all animals in which the respira-
tion is performed by a special organ, the
blood is sent to it from the heart, and
retires from it by a special system of
canals ; the circulation thus established
is called the respiratory or the lesser
circulation, whilst that through the
body is called the greater. We shall
consider, first, the circulation in man, Fig. 38.— Capillary Ves-
and this will serve as a standard of sels in the Foot of the
comparison with others.

* a, arteries,
culating fluids.

, veins. The arrows point out the direction of the cir-
E 2

52 ZOOLOGY.

Description of the Circulation of the Blood in the Higher
Animals.

§ 92. The Heart. — In man, and all animals similarly or-
ganized, the heart is lodged "between the lungs and in the
cavity of the chest called by anatomists the thorax (Figs. 5
and 58) : its lower extremity is directed somewhat obliquely
towards the left side and forwards ; and its upper extremity,
from which spring the great vessels, is fixed to the neigh-

vj ac i ac vj

T>. . T
Eight Lung.

od vc iid a vg

Fig. 39. — Lungs, Heart, and Principal Vessels in Man.*

bouring parts, nearly in the mesial plane of the body.
Throughout the rest of its extent the heart is free, but is
surrounded by a fibro- serous membrane, called the pericar-
dium, which not merely forms a shut sac for containing the
heart, but gives to its surface a smooth covering, by which it

* od, vd, right auricle and ventricle; — vg, left ventricle; — a, aorta;
— ac, carotid arteries ; — vc, vena cava inferior j— vj, jugular veins j —
t% trachea.

THE BLOODVESSELS.

53

is enabled to move freely in the cavity so formed; an aqueous
fluid, the liquor pericardii, lubricates it at all times.*

The general form of the heart is that of a cone or irregular
pyramid reversed ; it is almost wholly flesh, hollow, and in
man about the size of the closed hand or fist. In all the
mammalia and in birds the heart is composed of four cavi-
ties,— namely, a right auricle and ventricle, and a left auricle
and ventricle ; these are separated from each other by a ver-
tical septum (Fig. 40), cutting off all communication between
those of the right side and those of the left.

Each auricle communicates only with its corresponding
ventricle (Figs. 40 and 42).

The two ventricles occupy the lower part of the heart, and
do not communicate with each other, but with their cor-
responding auricles. The orifices are called the auriculo-

VenaCavaSup. Art.Pulm. Aorta. Art.Pulm.

Pulmonary Veins.
Eight Auricle.

Tricuspid Valve.
Inferior Vena Cava.

Eight Ventricle.

Pulmonary Veins.

Left Auricle.
Mitral Valve.

Left Ventricle.

Septum. Aorta.
Fig. 40.— Theoretical Section of the Heart in Man.

ventricular orifices, right and left. The left cavities of the
heart contain arterial blood ; the right, venous. The auricles,
having to propel the blood only into the ventricles, are not so

* The pericardium is a fibro-serous membrane. By investing the surface
of the organs, as well as the walls of the cavities containing them, the serous
membranes provide for the friction of such organs as are in constant motion,
as the brain, heart, lungs, and abdominal viscera : analogous membranes
are found in the articulations.

ZOOLOGY.

Temporal
Artery •

Art.
Pediosa.

Vertebral
Artery.
Subclavian
Artery.

Axillary
Artery.

Brachial
Artery.

Peroneal
Artery.

Fig. 41. — Arterial System in Man.

THE BLOODVESSELS. 55

fleshy in their walls as the ventricles ; and of these the left is
much the stronger, as it has to drive the hlood through the
whole hody excepting the lungs ; whilst the right ventricle
merely propels it through the lungs.

§ 93. The Bloodvessels. — These vessels are divided into
arteries and veins. The walls of these tubes are formed of
membranes or tissues. In the arteries there are three tissues :
the inner, continuous with the inner membrane of the heart,
resembles the serous membranes ; the middle tissue is
fibrous and elastic ; the outer tissue, cellular and also elastic.
The fibres of the middle tissue are disposed circularly. In
the veins, the middle tissue is not so distinct, being composed
merely of fibres, irregularly disposed ; these are soft, exten-
sible, and longitudinal. Thus the physical properties of the
veins and arteries differ widely. The veins have thin walls,
which collapse when the vessels are empty ; and they heal
easily when wounded. On the contrary, the arteries when
cut across, remain open, and when wounded do not heal so
perfectly ; in order to close, they must be obliterated, either
by pressure or by the use of the ligature.

§ 94. Arterial System. — From a single artery, called the
aorta, springing from the left ventricle of the heart, all the
arteries of the body arise. It must, however, be borne in
mind that the artery called the pulmonary springs from the
right ventricle, and carries the venous blood to the lungs.
The accompaning figure (41) explains perfectly the course of
this great artery (the aorta), from its commencement in the
heart to its termination ; also of all the great branches
which arise from it.

§ 95. Venous System. — The veins originating in the
capillary vessels, in which the arteries terminate, follow .
pretty nearly the course of the arteries ; but they are more
numerous and more superficial. Many are situated imme-
diately beneath the skin, imbedded in the superficial fascia of
the body. Others follow the course of the arteries, to termi-
nate however at length in two large trunks, which empty
themselves into the right auricle of the heart (Fig. 39). ^

The veins of the intestines present this remarkable anomaly
— that they unite into a single trunk, which, instead of joining
the venous system, directly proceeds towards the liver, and is
ramified through that organ after the manner of an artery ;

* A smaller vein, called coronary, returns the blood which has circulated
in the walls of the heart into the same cavity. — R. K.

56

3?ig. 42.— Vertical Section of the Human Heart.*

tnese tendons oemg attacnea oy tneir otner extremities to me nesny columns
and fleshy walls of the ventricle. 3. Cavity of the right auricle. 4. Fleshy
columns strengthening the walls of the cavity. 5. Orifice of the great

MECHANISM OF THE CIRCULATION. 57

but the veins which leave the liver unite with the vena cava
inferior before that vessel enters the right auricle.

§ 96. Lesser Circulation. — The venous blood conveyed
into the right auricle by the two cavae and by the coronary
vein, passes from this auricle into the right ventricle, and by
its action is driven along the pulmonary artery into the lungs
(Figs. 39 and 40). The latter vessel is called an artery,
although it carries only venous blood. In the right lung it
divides into three branches, and in the left into two ; thus
corresponding as it were with the number of the lobes of each
lung.

§ 97. The pulmonary veins, as they are called, carry back
from the lungs the whole of the blood which has been conveyed
to these organs by the pulmonary artery. In the capillary
system of these vessels, the blood has been in the mean time
aerated, revivified, and arterialized, and fitted once more to
perform its part in renovating the organs and maintaining
life. From the left auricle, in which the four pulmonary
veins terminate, the blood passes into the left ventricle, and
by its powerful action is driven through the aorta and its
branches into all parts of the body, to return once more by
the veins to the right auricle of the heart. Thus is completed
the double circulation in man, mammals, and birds.

Mechanism of the Circulation.

§ 98. Movements of the Heart. — The cavities of the
heart being muscular, contract and dilate : the dilatation is
called the diastole,* the contraction, systole.-^ As the auricles
of the heart dilate, they receive the blood, the right that of
the body, the left, that which is returning from the lungs ;
when full, they contract on their contents, forcing the blood
into the ventricles ; these in their turn suffer dilatation as
they fill, and, contracting suddenly, force the blood, the right
into the pulmonary artery, the left into the aorta. These
movements of the heart continue whilst life endures, and are
much influenced by various circumstances, such as exercise,
disease, &c. The number of these contractions, usually felt
in the radial artery at the wrist, varies with years ; they are
most frequent in the young, and average about seventy in
the adult, at noon. They are affected by every change in the
position of the body.

* From Siaore'AAco, I dilate, f From crvoreAAw, I enclose.

58

ZOOLOGY.

§ 99. Passage of the Blood into the Cavities of the
Heart. — This has been already de-
a scribed, but may be thus again briefly

adverted to. The blood having an
arterial character, returns from the
lungs into the left auricle. This
auricle communicates with the left
ventricle by an opening called the left
auriculo-ventricular aperture, through
which the blood flows from the auricle
into the ventricle. In this passage
is placed a valve, called mitral, permit-
ting the blood to pass, but not to re-
turn. The arterial blood now collected
in the ventricle is acted on by this fleshy cavity, and forced
into the aorta ; at the entrance of the aorta are three valves,

Fig. 43.— Section of the
Heart.*

Fig. 44. — Valvules of the Heart and Arteries.t

* Theoretic section of the heart, to show the mechanism of the play of the
valves : a, auricle receiving the veins e e ; — b, ventricle separated from the
auricle by the valvules c ; — d, fleshy bridles or stays of these valvules ;
— -f, artery springing from the ventricle j — g, valvules situated at the entrance
of the artery.

t Upper surface of the heart, the auricles having been removed. —
1, auriculo-ventricular orifice, obliterated by the tricuspid valve ; 2, fibrous
ring surrounding the orifice ; 3. left auriculo-ventricular orifice, surrounded
by a ring, and closed by the mitral valve ; 4, orifice leading into the aorta
from the left ventricle, closed by the semilunar valves ; 5, orifice leading
into the pulmonary artery from the right ventricle, also provided with three
semilunar valves.

MECHANISM OF THE CIECULATION. 59

the semilunar, permitting the blood to flow freely into the
artery but not to return into the ventricle ; distributed by
the aorta and its branches to every part of the body and to
the fleshy walls of the heart itself, the blood is taken up by
the venous capillaries, and returned to the right auricle by
the two venae cavse and coronary vein; collected in this
auricle it is strictly venous blood, but has already received
the product of digestion. From this auricle, and by its
action, the blood is driven through the right auriculo-ventri-
cular orifice into the right ventricle ; the tricuspid valve per-
mits it to pass into the ventricle, but not to return. By the
action of this ventricle the blood is forced into the pulmonary
artery, and by it to the lungs, thence to be returned (aerated)
to the left auricle by means of the pulmonary veins. At the
entrance of the pulmonary artery there are, as in the aorta,
three semilunar valves, permitting the blood to pass freely
into the artery, but not to return. From the mechanism
alone of the valves alluded to, the circulation of the blood
might easily have been foretold.

§ 100. Course of the Blood in the Arteries. — Contrary
to what might have been expected, the blood flows in the
arteries in a continued stream, and with considerable force.
This is due chiefly to the action of the heart itself, but partly
also to the elasticity of the arteries themselves. The influence
of the elasticity of the walls of the arteries on the passage of
the blood is proved by placing two ligatures, at a certain
distance from each other, on a large artery in a living animal,
and then puncturing the vessel at any point between the
ligatures. The blood contained in this insulated portion of
the vessel is thrown out of it with considerable force. Thus,
by means of the elasticity of the arteries, the jet of blood, or
the intermittent movement impressed on the blood by the
action of the heart, is transformed into a continuous' flow or
stream. In the capillaries, it is presumed that the blood
flows on by this means alone ; but some suppose them to be
muscular.

§ 101. Thus the left cavities of the heart perform the
function of a double forcing-pump (Fig. 45), so arranged,
that the two pistons alternate in their movements; thus
the liquid chased from the first body of the pump (a) is
introduced into the second (5), without being able to retrace
its steps, and is thrown by this second pump into the canal
(f) representing the arterial system.

60

ZOOLOGY.

Fig. 45.*

§ 102. When the finger is gently pressed against an

artery resting on a firm
surface, as a bone, an
impulse or jet is felt to
strike the finger regu-
larly. This is due to the
action of the left ven-
tricle on the fluid, and
is a phenomenon pro-
duced in a great measure
by the pressure exer-
cised by the finger. It
is called the pulse, and
is most usually felt at
the wrist (Fig. 41), the
radial artery being fa-
vourably placed in this
respect.

§ 103. The blood does not reach all the organs with the same
swiftness. Distance from the heart is one cause : but it is not
the only one. The arteries run mostly in a tortuous manner,
and this causes, as is well known, a retardation of the fluid
circulating. By a vast increase of minute branches, the blood
is spread into many channels ; hence arises another cause of
retardation as regards the arteries. Finally, Nature, all-fore-
seeing, provides, by numerous anastomoses or junctions of
the vessels, for any accidental stoppage or obliteration of the
larger or smaller trunks.

§ 104. Course of the Venous Blood. — The blood passes,
by means of the capillaries, from the arteries into the veins.
The impulsion it first receives from the heart determines
its course in the veins. This is proved experimentally, by
placing a ligature on the artery supplying certain veins, and
thus cutting off the action of the heart ; the hsemorrhage from
a punctured vein will cease, even although the vein be full of
blood, and will return when the action of the heart is allowed
to influence it, by removing the ligature from the artery.

* a, body of the pump representing the auricle, and receiving the liquid
by the canal c; b, body of the pump representing the ventricle ; d, canal of
communication, representing the auriculo-ventricular orifice, furnished with
a sucker permitting the fluid to pass from a to b, but opposing its return ;
ey the sucker or valve, situated at the opposite orifice of the pump b, repre-
senting the semilunar valves of the aorta, and having the same action as the
preceding valve or sucker ; /, canal, representing the aorta.

COURSE OF THE BLOOD IN ANIMALS.

61

But there are other circumstances influencing the motion
of the blood in the veins. These vessels, and more especially
those of the limbs, are provided with valves (b), permitting
the blood to flow towards the heart, but preventing its reflux
toward the capillaries. Every intermittent compression of
these vessels contributes to the return of the blood to the
heart.

§ 105. The dilatation of the «

chest caused by respiration faci-
litates the return of the blood
towards the heart. By expira-
tion the movement of the blood
in the veins is momentarily in-
terrupted ; and the double motion
observed in the brain, when a
portion of the skull-cap has been
removed, is due partly to respi-
ration, partly to the resistance
which the base of the brain
offers to the dilatation of the
arteries situated between the base
and the skull.

§ 106. The course of the
venous blood, and the mecha-
nism of the cavities through which it passes from the
veins to the lungs, by means of the right auricle, ventricle,
and pulmonary artery, has been already described. In the
capillaries of the pulmonary artery the blood is changed into
arterial, and so returns by means of the pulmonary veins to
the left auricle of the heart.

Course of the Blood in Different Animals.

§ 107. Mammals and Birds. — The circulation in these
two classes of animals is the same (47). It is what is called
a double circulation, the blood passing through two sets of
capillaries — one belonging to the body, the other to the lungs;
the former serving for the nutrition of the body, the latter
for the aeration of the blood. This kind of circulation has
also been called complete, which means that the whole of the
blood circulates through the lungs before being restored to
the body.

Before birth there exists an opening between the right and

Fig. 46. — Vein, laid open.

62

ZOOLOGY.

Smaller Circulation.

Pulmonary Artery.

Eight Auricle.
Heart.1

Venae Cavae.

Eight Ventricle. •'

Pulmonary Veins.
Left Auricle.

Left Ventricle.

Greater Circulation.
Fig. 47. — Mammals and Birds.

Smaller Circulation.

Vense Cavae.

Fig. 48.— Eeptiles.

Heart.

Aorta.

' Single Ventricle.
Greater Circulation.

COURSE OF THE BLOOD IN ANIMALS.

63

Smaller Circulation.
Ventricle. |

Auricle.

Veins.

Fig. 49.— Fishes.

- Heart.

-, Dorsal Artery.

Greater Circulation.

»
Smaller Circulation.

Fig. 50.— Crustacea.*

Branchio-Cardiac
Canals.

Heart.

Arteries.

Greater Circulation.

* In all these figures the shaded parts represent the veins ; the parts
simply traced represent the arteries ; the dotted circle represents the heart.
Finally, the arrows point out the direction of the sanguine current, which
is the same in all the figures.

64 ZOOLOGY.

left auricles, by which the blood conveyed to the heart by the
vena cava inferior passes directly into the left auricle. This
blood comes mostly from the placenta. The pulmonary
artery also, before birth, divides into three branches instead
of two, as in the adult ; the centre branch passes into the
aorta. This peculiar mechanism connected with foetal life dis-
appears soon after birth, leaving merely traces of its existence.

§ 108. Reptiles. — In this class the- circulation is not com-
plete. The heart has only three cavities instead of four, as in
mammals and birds — namely, two auricles and one ventricle
(Fig. 48) ; the venous blood coming from the various parts of
the body is poured by the right auricle into the single ven-
tricle, which receives also the arterial blood from the left
auricle — a portion of this mixed blood is returned to the
lungs, and the rest proceeds to nourish the body. The circu-
lation in reptiles resembles somewhat that of the foetus of the
higher classes of animals. From the heart (ventricle) there
proceed two arteries or aortce, which, after having each fur-
nished a cross or arch, one to the right the other to the left,
reunite to form a single trunk (51). In some reptiles, the
crocodile for example, the circulation is somewhat different.
We shall describe it when speaking of these animals.

§ 109. Fishes. — In Fishes the circulation may be said to
be still more simplified. The heart has only one ventricle
and one auricle. This auricle receives only venous blood
returned to it from all parts of the body. From this cavity it
passes into the ventricle, from which springs a single artery,
having at its origin a strong arterial bulb (Fig. 49). Through
this single artery it is conveyed first to the gills, and the
vessels returning from these unite to form a single dorsal
artery (the aorta), by whose branches the blood is conveyed to
all parts of the body, returning by the veins to the auricle
from which it started. Nevertheless, the circulation is here
complete, since all the blood is aerated before its employ-
ment in nourishing the body (Fig. 49, p. 63).

§ 110. Mollusca. In most of the mollusca the circulation
resembles that of fishes, but the heart is aortic and not pul-
monary— that is to say, it is placed in the course of the blood
proceeding from the respiratory apparatus to the body, and
the venous system is more or less incomplete. The heart in
these animals is composed usually of a ventricle (Fig. 53 h),
whence spring the arteries (i), and of one or two auricles in
communication with the vessels (o), which carry the arterial

MECHANISM OF THE CIECULATION. 65

blood from the respiratory apparatus (d), which this liquid
reaches by venous canals more or less complete (n). Thjs is the
case in snails, oysters, and all acephala, as well as the class
gasteropoda ; but sometimes there exist no auricles, and a kind
of venous hearts is found altogether distinct from the aortic
ventricle, and situated at the base of the respiratory organs ;
this takes place in the sepia, and other cephalopoda. How-
ever it may be, the arterial blood in all these animals tra-
verses the heart, then proceeds to all the parts of the body,
and is afterwards directed towards the respiratory organs.
But in this latter part of its course, the blood is not always
contained in vessels properly so called. Sometimes the veins
are altogether wanting, their place being supplied by lacunae,
or void spaces filling up the intervals of the organs ; at other
times veins exist in some parts of the body, whilst elsewhere
in the same animal their place is supplied by venous canals,
having no proper tunic, but consisting merely of the inter-
organic lacunae, or the large cavities of the body, as the
abdominal cavity (m, Fig. 53). Finally, the blood, after having
undergone the action of the air, returns to the heart to com-
mence its course anew.

§ 111. Crustacea. — In lobsters, crabs, and other animals
of this class, the blood follows the same course as in the mol-
lusca ; only the heart, destined to transmit the blood to all
parts of the body, consists of a single ventricle (Fig. 50), and
the veins are everywhere replaced by irregular cavities, which
have not the form of vessels, and which constitute, in the
neighbourhood of the branchiae, a sort of reservoirs, called
venous sinuses (Fig. 54). The venous blood thus bathes all
the organs ; but the nourishing fluid is once more collected
into vessels, whence it proceeds from the gills to the heart.
The circulation is, consequently, semi-vascular and semi-
lacunar.

§ 112. Insects. — In insects the blood is no longer con-
tained in any particular system of vessels ; there are neither
arteries nor veins, and the nourishing fluid is spread about
in the interstices of the organs ; still the circulation, such as
it is, is animated by the action of a vessel called dorsal, situ-
ated in the mesial plane of the body above the digestive tube
(Fig. 55). We shall consider, further on, the route followed
by the blood in the organism of those animals with a lacunar
circulatory apparatus.

§ 113. Worms. — In the worms of the class annelides (such

66

ZOOLOGY.

Carotid
/ Artery.

/ Arches of

x the Aorta.

>•-' Left
'•' Auricle.

Ventricle
of the
^. Heart.

Pulmonary
..~"""' Vein.
....-•- --" Brachial

Artery.

_^-- Pulmonary
Artery.

Lungs.
Stomach.

Kidneys.

Ventral
Aorta.

Fig. 51.— Circulatory Apparatus in the Lizard.

MECHANISM OF THE CIBCULATION.

67

as the leech and earth-worm) there exists, on the other hand,
a complete vascular apparatus ; but generally there is no
heart, properly so called, and the blood is set in motion by

Branchial Artery.

Arterial Bulb..,

Ventricle of the
Heart.

Auricle of the
Heart.

Venous Sinus.

Vena Portae,
Liver, &c.

Intestine.

Vena Cava. ~W''T~"~~\"

Branchial Vessels.

Dorsal Artery.

Kidneys.

Dorsal Artery or
Aorta.

Fig. 52.— Circulatory Apparatus in the Fish.
Jf 2

68

ZOOLOGY.

movements of the vessels themselves, by contractions of the
principal vessels. Thus the course of the blood is much less

Fig. 53.— Circulatory Apparatus in a Mollusk.*
/ i a d b

Fig. 54.— Circulatory Apparatus in the Lobster.f

* Anatomy of the Snail. — a, the mouth ; b b, the foot ; c, the anus ;
d d, the lung ; ey the stomach, covered above by the salivary glands ; ff, in-
testine; g, the liver; h, the heart; i, aorta;./, gastric artery; I, hepatic
artery ; k, artery of the foot ; m m, abdominal cavity, supplying the place of
a venous sinus ; n n, irregular canal in communication with the abdominal
cavity, and carrying the blood to the lung ; o o, vessel carrying the blood
from the lung to the heart.

t a, the heart ; 6, the ophthalmic artery ; c, the antennar artery ; d, the
hepatic artery ; e, superior abdominal artery ; ,/, sternal artery ; g y, venous
sinuses, receiving the blood coming from various parts of the body, and
transmitting it to the respiratory apparatus (the branchiae, h), from whence
it returns to the keart by the branchio -cardiac vessels, i.

OF THE RESPIRATION.

regular than in the various animals of which we have just
spoken, and frequently the direction is not constant.

§ 114 Zoophytes. — There exists even in some zoophytes,
as in polyps, a kind of circulation, produced hy the action of
the vibratile cilia with which the walls of the cavity, acting

Fig. 55. — Circulation in Insects.*

at once as stomach and intestine, are provided. By means
of these cilia the contained liquids are kept constantly in
motion. This cavity is sometimes single, but in some it
sends branches to various parts of the body.

§ 115. Such are the principal modifications hitherto ob-
served in the mode by which the circulation of the blood is
effected in various classes of animals. Let us now consider
the phenomena which happen whilst it passes through the
circulatory apparatus.

OF THE RESPIRATION.

§ 116. The arterial blood, by its action on the living
tissues, loses its vital properties, which can only be restored

* The arrows point out the direction of the currents : — a, dorsal vessel, in
which the blood moves from behind forwards ; b, principal lateral currents.

70 ZOOLOGY.

to it by being exposed to the action of the air whilst tra-
versing in vessels an organ adapted for this purpose. This
process of aeration is called respiration. The necessity for
this is proved by the simple experiment, if any such were
wanted, of placing an animal under the receiver of an air-
pump, and exhausting the air ; in a certain time the animal
dies asphyxiated. Wherever there is life, whether animal or
vegetable, air is essential. The term applies equally to aquatic
animals, which live by means of the air held in a kind of
solution or mixture by the waters in which they exist.

§ 117. The air we breathe, and which is essential to all
that lives, is a compound fluid. It is composed of, — 1. Watery
vapour, always present in greater or less quantities ; and 2.
In 100 parts of pure atmospheric air : there are 20 of oxygen,
79 of azote or nitrogen, with some traces of carbonic acid
gas. Oft-repeated chemical experiments have proved that it
is the oxygen alone which maintains life. The discovery of
this singular fact we owe (1777) to Lavoisier, a celebrated
French chemist, who was barbarously executed during the
French Eevolution.

§ 118. By the action of respiration the oxygen is with-
drawn from the atmosphere, and disappears ; in its place we
find carbonic acid gas; this gas is not respirable, i. e., if
breathed it destroys life. In the consumption of oxygen and
the production of carbonic acid gas, respiration essentially
consists.

§ 119. Although azote or nitrogen be not a vital gas, its
presence in the atmosphere seems necessary to dilute the
oxygen : and it has been observed that a certain quantity of
azote is absorbed and given out in the act of respiration.

§ 120. Finally, there escapes with the fluids expired a
certain amount of vapour, which becomes conspicuous in cold
weather ; this vapour is called pulmonary transpiration.

§ 121. It is whilst passing through the capillaries of the
lungs that the blood loses its dark venous hue, and becomes
of a bright vermilion arterial colour. Many experiments
have been made to prove that which seems obvious without
any.

§ 122. Theory of Respiration. — What becomes of the
oxygen which has disappeared, and what is the source of the
carbonic acid gas uniformly found as a product of respiration ?
The strong analogy existing between the phenomenon of
combustion, of a piece of charcoal for example, and respira-

OF THE BESPIBATION. 71

tion, induced Lavoisier to conjecture them to be almost
identical processes ; in both, the oxygen disappears, carbonic
acid gas is formed, and heat is disengaged.

But this theory must be abandoned, as opposed to subse-
quent experiments and facts ; carbonic acid gas exists already
formed in the blood, and is simply exhaled from the surface
of the vessels, whilst the oxygen is absorbed into the blood,
to be dissolved in it, and to bestow on its particles their living
qualities, characteristic of arterial blood.

§ 123. A simple experiment, made by William Edwards,
suffices to place this matter in a clear light. Place in a close
vase filled with nitrogen or azote, a frog ; in this gas the frog
can live for a considerable time. Now analyze it, and you
will find that, although deprived of oxygen, the animal con-
tinues to give out carbonic acid gas. There can then be no
combustion, as Lavoisier supposed.

§ 124. In fact, the blood always contains carbonic acid
gas dissolved in it ; and Magnus has shown that the blood
can dissolve a certain measure of any gas with which it may
be' brought in contact by giving out a portion of the gas
first absorbed when dissolving a portion of the second.
Thus, by agitating blood in hydrogen, a certain amount of gas
is absorbed, and a certain quantity of carbonic acid gas is set
free. The same happens when oxygen is used instead of
hydrogen, and the blood assumes an arterial character.

§ 125. It results, indeed, from numerous experiments,
that, as the changes observed to take place during respiration
equally happen to blood when contained in a bladder, oxygen
disappearing by being absorbed through the walls of the
bladder, and carbonic acid gas appearing, which must have
come from the blood and equally passed through the walls
of the bladder, the phenomena of respiration must in a great
measure be chemical, since they take place as well in bl'ood
withdrawn from the body as in the pulmonary vessels.

§ 126. What happens in the respiratory act seems to be as
follows : the venous blood coming from all parts of the body
reaches the lungs, holding in solution a considerable amount
of carbonic acid gas, a little azote, and some traces of oxygen.
As it passes through the lungs it comes as it were in contact
with the air, and dissolves a portion ; oxygen and a certain
amount of nitrogen are thus absorbed, and these gases by
being thus taken into the blood, expel a certain amount of
carbonic acid gas and of azote ; the carbonic acid gas exhaled

72 ZOOLOGY.

equals pretty nearly the amount of the oxygen absorbed ; the
azote exhaled and absorbed are nearly equal, and in addition
there is the vapour or pulmonary transpiration. Thus the
blood loses carbonic acid gas, azote, and water, whilst it
becomes charged with oxygen and azote ; and thus it may be
proved that arterial blood holds dissolved much more oxygen
than venous blood, and that it is to this gaseous fluid that
arterial blood owes its colour and qualities. Respiration
consists, then, in the phenomena of absorption and exhalation,
by means of which the venous blood, coming in contact with
the atmospheric air, parts with its carbonic acid, and becomes
charged with oxygen.*

As regards the source of the carbonic acid gas contained in
the blood, and thus exhaled during the respiratory act, there
is reason to believe that it originates in the union of the
oxygen absorbed with the carbon of the organic particles in
all parts of the body, whether contained in the blood or
removed from the living tissues. The essential act, then, of
respiration seems to be a combustion going on in the depth of
the tissues, and the exchanges effected in the lungs are only
the preliminaries to this work.

§ 127. Activity of Respiration. — Respiration, essential
to all life, varies in activity in different animals.

In birds it is the most active ; they consume more air in
a given time, proportionally, than any other class of animals,
and they soonest die asphyxiated when deprived of it.

Mammals have also a very active respiration, and many
experiments have been made to determine the quantity of
oxygen required by man in a given time. Now this -has
been found to vary with age and a variety of circumstances ;
about 500 quarts, or rather more, per day, may be assumed to
be the average. Now, oxygen forms only 21 per cent, of the
atmospheric air : hence about 2750 quarts of air are required
per hour for the support of this respiration.

Animals of the inferior classes generally, and especially
those living in water, have the respiration much less active.

To meet this enormous consumption of oxygen, which

* It is right to observe, that the quantity of carbonic acid gas contained in
the blood, though small, is sufficient to account for the volume of this gas set
free during respiration. Thus, in man the blood contains at least Ath of its
volume of gas, arid as the quantity of blood which traverses the lungs in a
minute may be valued at 250 cubic inches, about fifty cubic inches of this
gas must pass in the same time. Now the highest valuation of the gas given
off in respiration during a minute does not exceed twenty-seven cubic inches.

APPABATTJS OF BESPIBATION. 73

would surely end in the destruction of life on the globe if
not obviated, nature employs the respiration of plants.

Vegetables absorb the carbonic acid gas spread through
the atmosphere, and under the influence of the sun's rays
they extract the carbon, and set free the oxygen. Thus
animals supply carbon to vegetables, while the latter return
oxygen to animals.*

§ 128. There exists a kind of relation between the viva-
city of the movements of any animal and the activity of its
respiration, which may be estimated by comparing the move-
ments of a frog and butterfly.

§ 129. The activity of the movements varies also in the
same animal according to the circumstances in which it is
placed; and it may be established as a general rule, that
whatever diminishes the vital energies tends to diminish the
quantity of oxygen absorbed and of carbonic acid given out ;
and vice versa.

Thus in young animals during sleep and after fatigue, the
respiratory act is not so energetic as when the opposite
circumstances prevail. Let us now attend to the organs by
which this important function is carried on, and their various
modifications in different animals.

Apparatus of Respiration.

§ 130. In animals of very simple organization there
exists no special respiratory organ. They absorb the air by
the general envelope of the body. This happens also in the
higher animals, and even to man himself ; but in all the
higher animals a special organ is provided for this act ; its
vascularity and softness, and spongy character, contrasting
strongly with the external integuments of the body.

§ 132 . Again, these organs are modified according as the
animal is aquatic, properly so-called, or terrestrial and aerial.
In the former, the organs are called gills or branchiae ; in the
latter, lungs or tracheae.

§ 132. Organs of Aquatic Respiration. — Gills vary much
in their form. Sometimes they more resemble tufts or tuber-
cles, which have a texture softer than the rest of the skin,
and are better supplied with blood. In others, these organs

* It might be supposed that the air of cities must be less pure in respect
of the amount of oxygen than that of the country; but experiment shows
that this is not the case.

74

ZOOLOGY.

are composed of a number of branched filaments, and resemble
little trees or vascular branches (a a, Fig. 56).
Finally, in others, they are formed in small
membranous lamellae, disposed like the leaves
of a book, or like the teeth of a comb. The
first of these arrangements takes place in
many marine animals, as in the arenicola, so
common on the coasts. The second may be
observed, also, in several of the annelida and
in some of the Crustacea. Finally, the last
is common to most molluscan animals and
fishes.

It is also to be observed, that in the in-
ferior animals the branchiae are mostly situated
externally, so as to float freely in the sur-
rounding water; whilst in the more highly
organized, as the mollusks and fishes, the
branchiae or gills are enclosed in a cavity, into
which the water has free access, and may
easily be renewed.

§ 133. Organs of Aerial Respiration :
Respiration in Air. — The organs serving for
this form of respiration affect sometimes the
form of trachea, sometimes of lungs.

The tracheae (Fig. 56) are vessels which
communicate with the exterior by apertures
called stigmata, and ramify in the depth of
the organs. They convey the air to these
organs, and thus the function of respiration
is carried on in every part of the body. This
mode of breathing is peculiar to insects and
to some arachnidae (spiders).

§ 134. The lungs are pouches, more or less
divided into cells or cellules, which also re-
ceive air into their interior, and whose walls
are traversed by vessels containing blood, thus
exposed to the vivifying action of the air.

There exist lungs, but in a state of the
greatest simplicity, in most spiders; and in
. some mollusks, as in snails. Keptiles, birds,
Sea Worm— and mammals also have lungs.

LWorm ot?S § 135- In man' as in al1 mammals> the
Fishermen, lungs are lodged in a cavity, called the thorax,

F- Th

*

APPARATUS OF BESPIBATION.

75

occupying the upper part of the trunk (Fig. 5, p. 20). These
organs are, as it were, suspended in this cavity, and are en-

Fig. 57. — Respiratory Apparatus of the Insect Nepa;
Water Scorpion.*

veloped by a membrane or membranes (one for each lung in
most mammals) called the pleurae ; and these membranes, like

* a, the Mlad ; &, base of the feet of the first pair; c, first ring of the
thorax ; d, base of the wings ; e, base of the feet of the second pair ; ft stig-
mata; g, tracheae ; h, aerial vesicles.

7.6

ZOOLOGY.

all serous membranes, besides investing more or less com-
pletely the exterior of the organs, also line the walls of the
thorax, thus providing for the security and mobility of the
organs themselves.1* The lungs are two in number, com-
municating with the exterior by means of a single air-
tube, the trachea (b, Fig.
58), which ascends through
the fore part of the neck, and
opens into the pharynx.

This canal or tube is
formed of a series of small
cartilaginous bands, incom-
plete behind. It is lined by
a mucous membrane, which
is of the same nature as the
mucous membrane of the
mouth and nostrils, and is
continuous with it. f Finally,
inferiorly, the trachea sub-
divides into two branches
called bronchi, which ramify
in both lungs like the roots
of a tree in the soil (c e,
Fig. 58).

§ 136. The lungs show
internally a vast number of
small cells, into each of
which a branch of the cor-
responding bronchus opens.
A soft, delicate, and vas-
cular membrane lines the walls of these cells and air tubes,
and it is to these that the alternate branches of the pulmonary

Fig. 58.— Lungs and Trachea
in Man.J

* The pleurae are arranged, in fact, like other serous membranes.

t The surface of the membrane of the trachea is covered with a fine down,
each hair of which exhibits vibratile movements, called also ciliary. This
vibratile movement determines in the liquid in contact with their surface,
currents, which are often very rapid, and which persist even after a portion
of the membrane has been removed from the body. The cilia are micro-
scopic. The direction of the current seems to be from the exterior towards
the interior, and the same movements may be observed on the surface of
tho nasal fossae, but nothing of the kind is to be seen in the pharynx.

J One of the lungs (the left) is left in its natural condition (d) ; but in the
other the substance has been destroyed, in order to expose the right bron-
chus and its ramifications in the lung. $

a, larynx and superior extremity of the trachea ; b, trachea ; c, division
into bronchi ; d> one of the lungs ; e, bronchial ramusculee.

APPARATUS OF RESPIRATION.

77

artery are distributed, by means of which, now become capil-
laries, the venous blood is exposed to the action of the air.

The smaller the cells, the greater will be the extent of
the membrane, and the more extended the surface upon which
the blood is exposed to the action of the air. The smallness
of the cells and the activity of respiration are thus in a direct
ratio to each other ; and this is proved by contrasting the

Fig. 59.— Thorax of Man.*

large pulmonary cells in the lungs of the frog with the
microscopic cells which we find in the lungs of birds and
mammals.

§ 137. But air, as air, never penetrates beyond the little

* On the left side the muscles have been removed. The arch forming the
diaphragm towards the interior of the chest is seen on the left side, g, and on
the right side a dotted line marks the extent of the ascent of the same muscle
on the right side ; h, pillars of the diaphragm attached to the lumbar ver-
tebrae; i, elevator muscles of the ribs ; d, collar-bone.

78 ZOOLOGY.

cells, or cul de sacs, in which the air tubes terminate in mam-
mals. In birds, some of these air tubes open into large
membranous pouches, which proceed as far as the limbs, and
conduct the air even into the interior of the bones. Thus
respiration becomes more active in this class of animals.

§ 138. Mechanism of Respiration in Man. — By the
movements of inspiration and expiration performed by the
walls of the thorax or chest, the air is constantly renewed in,
and expelled from, the lungs. The walls of the chest are
moveable, and more especially one, which is not seen, the
diaphragmatic wall ; dilated by a muscular effort, the air
rushes into the cavity through the nostrils and trachea,
pressed on by the whole weight of the incumbent atmosphere.
To expel the air from the lungs, it is only necessary that this
muscular action should cease for an instant ; a forcible expira-
tion is effected by means of a voluntary effort, and is only used
occasionally. Respiration is wholly an instinctive action.

To understand its mechanism, so simple in its results, so
complex in the machinery, it is first necessary to examine the
structure of the thorax.

This cavity (Fig. 59), has the form of a conoid, with the
summit upwards and the base downwards, and its walls form
a kind of cage, with an osseous basis composed of the ribs,
the sternum, and a portion of the vertebral column. The
spaces left between the ribs are filled with the intercostal
(internal and external) muscles; the scaleni pass from the
cervical vertebrae to the first and second ribs ; powerful
muscles also proceed from the shoulder and arm-bones to the
ribs, thus contributing in every way to enable the animal to
act powerfully during inspiration, when the great muscular
efforts of the body are being made ; and in addition, and that
the most important of all, the abdominal wall of the thorax is
formed chiefly by the diaphragm, the great muscle of respira-
tion. ^

§ 139. The dilatation of the chest may be effected in two
ways — by the contraction of the diaphragm or by the eleva-
tion of the ribs.

In repose (expiration) the diaphragm forms an arch towards
the chest ; in action (inspiration) it contracts and descends
towards the abdomen, pushi ig the contents of the abdomen
before it. Thus the capacity of the chest is enlarged, and as
the vacuum thus formed in the lungs is gradually being
established, the external air rushes in to fill up the space.

APPARATUS OF RESPIRATION. 79

The play of the ribs is rather more complex. These osseous
arches, extending from the vertebral column to the sternum
(with the exception of the lower ones), and articulated with
both, are much lower anteriorly than posteriorly, and thus
admit of elevation and depression. As the ribs are raised,
they rotate on themselves, and thus the cavity of the chest
becomes enlarged in all directions. They raise the sternum
with them.

§ 140. In expiration, the diaphragm is relaxed; the
external air acts on the walls of the chest ; the elasticity of
the lungs assists, and thus the air is expelled from the lungs ;
the intercostal muscles also cease to play. But in forcible
expiration generally, partly a voluntary act, the muscles of the
abdomen and others assist in forcing the air from the lungs.

§ 141. Under ordinary circumstances, the amount of air
taken in at each inspiration does not exceed the seventh part
of what they can contain ; on an average it may be estimated
at about the third of a quart. The number of the respiratory
movements varies with age and a variety of circumstances.
They are most frequent in the young; in the adult the
average is sixteen per minute.

Thus, during ordinary circumstances, there enters into the
lungs of an adult male about 5^ quarts of air per minute, or
about 330 by the hour ; 7920 by the day.

§ 142. Sighing, yawning, hiccup, laughter, and sobbing,
are but modifications of the ordinary actions of respiration.

Sighing is a deep and prolonged inspiration, not always
caused by a moral sentiment, but occasionally by a feeling
that the respiratory act does not proceed with sufficient
energy and rapidity.

Yawning is an inspiration still deeper, accompanied with,
an almost involuntary and spasmodic contraction of the
muscles of the jaw and pendulous palate.

Laughing seems to depend on a series of rapid movements
of the diaphragm ; sobbing differs but little from laughing,
though expressing passions and feelings of so opposite a cha-
racter.

§ 143. Mechanism of Respiration in other Animals. —
The mechanism of respiration is essentially the same in all
mammals, birds, and reptiles ; in the two latter classes, how-
ever, the diaphragm is more or less completely absent, and in
consequence it is principally by the play of the ribs that the
air is drawn into the lungs ; in the chelonia (turtle and tor-

80 ZOOLOGY.

toise), and the batrackia (frogs, salamanders, &c.), the thorax
is not formed so as to act as a suction pump, and accordingly
these animals swallow the air by a sort of deglutition.

OF EXHALATION AND THE SECRETIONS.

§ 144. We have seen how the nutrient matter is distri-
buted to all parts of the body by means of the blood ; we
have now to examine how the matters contained in the
general mass escape from it, whether into the interior or
directly from the body.

§ 145. Nutrition we have seen to be effected in two ways;
either, 1st, by the simple absorption into the body of matters
requiring no modification : 2nd, by the more complex function
of digestion : the first is almost mechanical ; the second par-
takes more of a chemical character.

In like manner nature, in freeing the body of the useless
substances and the necessary results of vital actions, employs
two methods of expulsion, exhalation, and secretion. The
first of these processes is almost physical, and depends on the
permeability of the tissues; by the second, peculiar substances
are selected from the blood, and eliminated, as it were, in
order to be expelled the body ; to effect this, certain organs
are required, and these are called secreting organs. The
process bears to simple exhalation the relation which diges-
tion does to absorption.

.« EXHALATION.

§ 146. The walls of the bloodvessels are permeable to
liquids. By this means, water, gases, and the thinner parts
of the blood generally, may pass through these walls by
exhalation; but they do not admit of the passage in this
way of the globules, or denser parts of the blood. This is
proved by injecting prussiate of potass into the veins of a
living dog ; the salt injected may be soon after detected in
the thorax and abdomen, mingled with the fluids, which are
constantly exhaled on the surface of serous membranes.
Spirituous and other liquors are perceivable in the breath soon
after being taken.

§ 147. Mechanism of Exhalation. — Exhalation is purely
a physical phenomenon, however it may be modified by the
presence of life. Thus, if into the vascular system of an animal,

SECEETIONS. 81

recently dead, an injection be thrown, composed of gelatine,
mingled with vermilion finely powdered, the fluid part of the
injection will escape into the adjoining tissues, leaving the
vermilion particles in the vessels ; thus imitating what seems
to take place during life.

§ 148. In fact, inhalation, already explained, and exha-
lation are strictly analogous, and take place in the same
way ; and their activity depends on the spongy and vascular
character of the tissue. In another sense, these functions are
in the inverse ratio of each other. By pressure on the veins,
the exhalation into depending parts may be much increased.

§ 149. Seat of the Exhalation. — Exhalations are either
external, that is, on the surface of the body ; or internal,
that is, on the surface of the internal cavities.

§ 150. External exhalation must not be confounded
with perspiration, or production of sweat ; it takes place on
the surface of the lungs as well as on that of the body, and is
called insensible transpiration, because, being evaporated by
the air, it escapes our notice. Men and animals lose much
daily by insensible transpiration, which, of course, is as con-
stantly restored; according to Sanctorius, the loss by insensible
transpiration in man amounts to fths of the whole daily loss.
The evaporation from the surface of the body varies with
many circumstances, as climate, &c. ; the escape of carbonic
acid gMs from the lungs is by means of exhalation merely.

§ 151. The serous membranes found in the interior of the
large cavities of the body are the seat of internal exhalations,
consisting chiefly of water, and a few salts, mixed with a
small quantity of animal matter. The exhalation which
takes place on these surfaces has an exact counterpoise in the
absorption going on at the same time ; when this is disturbed
the fluid accumulates, and dropsies take place, which receive
names according to their localities : hydrocephalus, in the
head ;. ascites, in the abdomen ; hydrothorax, in the chest
and pleurae ; and hydrops pericardii when the accumulation
takes place within the cavity of the pericardium.

SECRETIONS.

§ 152. The secretions are special humours, formed at the
expense of the blood, in and by organs destined especially to
eliminate them from the blood.

§ 153. They may take place on the surface of membranes,

82 ZOOLOGY.

as on the skin and mucous membranes ; but they are chiefly
found in connexion with certain bodies termed glandular,
whose essential structure seems to consist in small cavities,
extremely minute, or pouches or canals of extreme tenuity ;
these receive bloodvessels and nerves, the latter no doubt
playing an important part in the phenomena of secretion.
The glands have been divided into perfect and imperfect,
according as they are provided or not with a tube or duct
intended to carry away the product of the secretion.

§ 154. Glands, properly so called, may all be arranged, as
regards their intimate structure, under two heads, or types ;
as being composed either of small sacs, with orifices more or
less contracted, or of tubes of extreme minuteness ; and the
differences they present have a reference mainly to the mode
in which these, as it were elementary, structures are grouped.

§155. The small secreting sacs are called follicles, when
ow they are called crypts, and many such may be seen
on the surface of mucous membranes. When each has a
separate or distinct oritice opening on the surface, they are

Fig. 60. — Intimate Structure of a Composite Gland
(the Parotid) ; a Salivary.

called simple follicles, and many such exist on the surface of
the mucous membranes ; if grouped close together, but still
maintaining distinct orifices, they are called aggregated;
such are the glands of Meibomius on the eyelids, certain
gastric glands in some animals, &c. ; when grouped, but
having their orifices leading into a small cavity common to

SECRETIONS.

83

all, and thus ultimately communicating with the surface by
one or more apertures only, as in the amygdalae or tonsils,
they are called agglomerated follicles. At other times little
sacs, which form the essential structure of the glandular
bodies we now speak of, communicate with the exterior by an
elongated neck, so as to resemble a tube, terminated by an
ampulla, and there they may either remain isolated or agglo-
merated in bunches, by means of common excretory tubes,
which, in their turn, reunite successively, to terminate by a
single duct (Fig. 60). The secreting organs, which may be
called ampullary follicles, are met with in the simplest form
under the skin of certain fishes, and
seem also to form the odoriferous
glands found in the human integu-
ments. When grouped around a com-
mon branched secreting canal (Fig.
60), they form the greater number
of the composite glands, such as the
liver and salivary glands of mammals,
and are named by anatomists, Con-
glomerate Glands.

§ 156. The tubular- formed, se-
creting organs present also differences
analogous to those just described.
These tubes vary infinitely in size,
but are all closed at one extremity,
and open at the other for the escape
of the excreted matter; their varied
arrangements are seen in the glands
under the integuments in fishes, and
in the bilious vessels of some of the
lower animals; in the pancreatic
coaca surrounding the duodenum in
fishes ; in the gastric glands of several
birds ; finally, these same tubes (Fig.
61) may acquire an extreme length
without change in their calibre, clustered or heaped on them-
selves, to terminate in an excretory tube, but little ramified at
its origin, in such a way as to form a conglomerate gland,

* A, vertical section of a kidney. — a, cortical substance j 5, tubular sub-
stance; c, calyx and pelvis ; d, canal of the ureter.

£, intimate structure of this gland. — a, terminal portion of the urinary
tubes ; b, medullary portion of these same tubes ; c, their termination in the
calvx.

G2

Fig. 61.— Structure of
the Kidneys.*

84 ZOOLOGY.

such as the kidneys and other glands of great importance :
some glands have a reservoir placed in the course of the
excretory duct, intended to permit of the accumulation of the
secretion, and its residence therein for a time. The gall-
bladder (Fig. 33) and the urinary-bladder (Pig. 62) are
pouches of this nature.

§ 157. The imperfect glands vary still more in their
mode of conformation. Some are composed of small closed
cells, isolated or agglomerated ; others, called vascular gan-
glias, are composed of bloodvessels or lymphatics solely,
which, after dividing and subdividing, again reunite. As
examples of the first may be cited the ovarian vesicles and
the adipose cellules; of the second, the thyroid,* the thymus,")"
the spleen (Fig. 32), and the mesenteric ganglias are the
examples (§ 75). Their functions are unknown. J

§ 158. Nature of Secretion. — The secreting organs are
always disposed in the form of membranes, one surface of
which is bathed by the nourishing fluid,§ the other being
free and forming the interior of the cavity ; this is the utri-
cular surface. This surface, then, performs, as it were, the
office of a filter, allowing only certain substances to pass from
the interior of the bloodvessels into the interior of the secre-
tory tube. 1 1

§ 159. The secretions differ from each other, and from
the blood, out of which they are formed, in containing sub-
stances in great abundance, of which but very small quantities
are to be detected in the blood : they may contain free acids,
whilst the blood from which they are drawn is alkaline ;

* The thyroid is a spongy, ovoid, vascular mass, of a glandular appearance,
placed in the neck, and attached to the front of the trachea. Its enlarge-
ment constitutes bronchocele, and when aggravated, goitres. It is not present
in birds, reptiles, and fishes, and in animals still lower.

f The thymus is a glandular-looking body, extremely developed in the
foetus, but which diminishes after birth, and generally altogether disappears.
It is situated in the fore and upper part of the ci^est, behind the sternum,
and between the mediastina. It lies partly on the "pericardium.

J The recent experiments of M. Bernard seem to show that the liver, in
addition to its other functions, secretes a sugary substance, called qlycose,
which it pours into the blood, but which disappears soon after, probably con-
sumed by the respiratory act.

§ The blood-vessels distributed to the walls of the tubes and cavities form-
ing the secreting organs never communicate directly with their internal
cavities.

|| Kecent observations seem to show that the essential secreting organs are
minute cellules or utricles, of which the inner wall of the secreting tubes are
formed ; these little cells empty themselves first, or are thrown off into the
interior of the tubes, and are as rapidly restored or renewed. They form the
layer called epithelium, forming the inner layer of all mucous membranes.

UBINAEY SECEETION. 85

sometimes they also are alkaline, but much more strongly
than the blood ; whilst some are characterized by the presence
of matters not to be found elsewhere, such as urea, casein,
butter, &c.

§ 160. It is probable that in all cases the secreted matter
exists in the blood already formed. It was thought, for
example, that the urea found in urine must be formed by
and in the kidneys, since it could not be detected by chemical
analysis in the blood; but if these organs be destroyed in a
living animal, or removed, urea will, after a certain time, be
formed in the blood, thus clearly proving that the kidneys do
not form it.

§ 161. Nature of the Secreted Liquids. — There is no
perceptible relation between the nature of the fluid and of the
gland secreting it ; and secretions, as pus, for example, are
formed by structures where no such secretion previously
existed; they alter also without any visible change in the
structure of the gland.

Nothing positive is known as to the nature of the secreting
function, but it is certain that the action of the nervous sys-
tem has a great influence over it. When the nerves of the
stomach have been divided in a living animal, the secretion
of the gastric juice ceases; and M. Bernard has shown that
when a certain portion of the spinal marrow is irritated, an
unusually abundant secretion of sugar takes place in the
liver, which sugar then appears in the urine.

This fact is remarkable, viewed in connexion with the
disease called diabetes.

Urinary Secretion.

§ 162. This function has its seat in the kidneys, two
large glands situated in the abdomen, on either side of the
vertebral column, and generally surrounded with much fat.
They are of a reddish-brown colour, and in shape resemble a
kidney-bean (Fig. 62). Their substance (Fig. 61) is com-
posed essentially of secreting tubes of extreme tenuity, and of
great length, which in mammals are turned on themselves in
every direction towards their free extremity, where they swell
into the form of an ampulla (a), and which afterwards proceed
in a straight line towards the middle of the inner edge of the
gland, so as to form a certain number of pyramidal fasciculi
(b), whose summit is partially enclosed by the membranous

86 ZOOLOGY.

cavity called calyx (c), and whose base, directed outwards, is,
as it were, encased in the cortical substance of the kidney,
formed out of the mass constituted by that portion of the
tubes which is massed into heaps rolled on each other ; the
other part is called tubular or medullary ; being the part formed
by the fasciculi themselves. In the
young, and in many animals throughout
life, such as the bear and otter, these
pyramids remain distinct, and each
kidney is then composed of several
separate lobes ; but generally they unite
together, and the calyces, which are but
excrementory tubes, unite to form a
pelvis or general reservoir, from which
proceeds the ureter (Fig. 61 d). A. great
number of bloodvessels creep between
these secreting tubes, and constitute, in
g. 2.-Urinary the cortical portion of the gland, a very
Apparatus.* close network, in the midst of which may
be seen certain spherical bodies, formed
also of bloodvessels collected into bunches in the interior of
the ampulla already mentioned.

The urine is formed in the cortical part of the kidneys.
It descends by the tubular part into the calyces, and thence
into the pelvis of the kidney; this terminates in the ureter
(Fig. 62 5), by which the urine descends to the bladder. This
latter organ is situated in the pelvis and behind the os pubis.
It is formed internally by a mucous membrane ; externally,
by a muscular and cellular layer. The peritoneum also par-
tially invests it, and gives it support. Inferiorly it terminates
in the canal of the urethra, by which the urine escapes from
the body.

§ 163. The urine is a yellowish acid liquid, which in
man, in the normal state, is composed of 93 parts water,
3 of a peculiar substance called urea ; a very small portion
of uric acid, lactic acid, various salts, as muriate of soda,
alkaline sulphates, phosphate of lime, &c., make up the 100
parts.

In carnivorous mammals the urine resembles that of man,
but the uric acid is wanting. In herbivorous mammals, the
urine is alkaline, and a peculiar substance is found, the hip-

* a, the kidneys ; 5, the ureter ; e, the bladder ; d, canal of the urethra.

NUTRITIVE DECOMPOSITION. 87

puric acid, as well as many earthy carbonates. In many
birds, and in most reptiles, the urine is composed mostly of
uric acid ; whilst in frogs and tortoises (turtles and tortoises)
it contains urea and albumen. Its composition in fishes
appears to be the same ; but in insects we again find uric acid.
Disease affects its composition in man.

§ 164. The extreme rapidity with which various drinks,
medicated or simple, pass from the stomach to the bladder,
and so escape externally by the urethra, is well known ; yet
it is certain that these fluids have first mingled with the blood
and been by it carried to the kidneys.

§ 165. A variety of circumstances, unnecessary to dwell
on, influence the activity of the secretion and modify its
character. The liquids, and especially water, taken into the
stomach escape either by pulmonary or cutaneous exhalation,
or by the kidneys as urine. With heat, the cutaneous exha-
lation is increased ; by cold, the urinary.

The amount of solid substances secreted by the kidneys
depends greatly on the abundance and nature of the food.
It is diminished during a prolonged fast ; and is rich in its
solid contents in proportion to the animalization of the food
employed.

§ 166. Various deposits are found in the urinary passages.
These are called gravel and urinary calculi, or concretions.
The former is almost always formed of uric acid. The depo-
sits commence usually, if not always, in the kidneys. Uri-
nary concretions also usually form in the kidneys, but
descending from these into the bladder, increase, by deposits
on their surface, to a size endangering life, and requiring for
their removal a surgical operation.

OF ASSIMILATION AND NUTEITIVE DECOMPOSITION.

§ 167. Assimilation. — The substances introduced into
the animal economy are there employed in two ways. They
serve for the formation of the different parts of the body
itself, or to support the respiratory combustion which con-
stantly exists in the interior of every animal so long as life
exists.

But neither animals nor plants can of themselves form any
of the simple substances of which their bodies are composed,
and therefore the foreign matters thus introduced must con-
tain all their elements.

88 ZOOLOGY.

The primary materials of the organism are carbon, nitrogen
or azote, hydrogen and oxygen ; but sulphur, phosphorus,
lime, and other simple bodies, are also required; it is essen-
tial, then, that such bodies should be introduced from with-
out. But animals do not possess the faculty of determining
the combination of these various chemical elements so as to
give rise to the various compound principles of which the
organism is formed ; or, in other words, these elements must
be already combined. Thus, it is not by introducing azote,
hydrogen, carbon, &c., into the body that an animal can
satisfy the wants of nutrition ; these substances must have
been already combined.

In a word, these principles must have been already com-
bined, so as to form organizable principles or viable matters.
Now, this only happens through the influence of life. It is
the vegetable kingdom, then, which directly or indirectly
furnishes to animal bodies the carbon and azote, and a certain
portion of hydrogen and oxygen ; water furnishes the greater
portion of the requisite hydrogen and oxygen ; the lime and
various other mineral bodies come directly from the mineral
kingdom.

From the atmosphere, animals derive the oxygen required
to consume the carbon and hydrogen ; and thus, in brief, to
meet the wants of the nutritive process, every animal requires
to convey into the interior of its organization, free oxygen,
organized matters rich in carbon, hydrogen, azote, water, and
various salts.

Before being adapted for nutrition, all substances must
assume a liquid or gaseous form; this is the object of diges-
tion. There exist three modes of ingress for the nutritive
matter — the skin, the respiratory mucous membrane, the
alimentary canal.

In man and animals which have an epidermis, absorption
by the skin is comparatively unimportant,-- by the lungs, some
liquid in the form of vapour is no doubt absorbed; but the
intestinal or alimentary canal, by means of its mucous mem-
brane, is the great route by which the matter destined to
assist in nutrition reaches the interior of the body.

§ 168. These nutritive elements are at first mingled with
the blood. This fluid, elaborated by processes not yet dis-
covered, becomes rich in all the compound principles of which
the tissues are in their turn formed; and it is out of this
fluid that all the organs of the body draw the materials fitted

NUTEITIVE DECOMPOSITION. 89

for their growth and support, each choosing the molecules
identical with its own nature.

It is this last act which constitutes assimilation.

§ 169. But nothing is known as to the real nature of this
act of assimilation, how brought about, how effected. Such
questions touch too nearly the very essence of the principle of
life, itself perfectly unknown in its nature. One thing is
certain, that in all animals possessing; a nervous system the
influence which this exercises over assimilation is distinct and
undeniable. Nor is the duration of life in the various organs
of the same animal the same ; the thymus gland, for example,
ceases to grow, and decays in the very young. The teeth
have their stated periods of existence ; the nails, the hair, and
generally the epithelial tissues, continue to grow in extreme
old age.

§ 170. The assimilating force possesses the property,
especially in the lower animals, of restoring parts which have
been destroyed; bones are reunited by bone after being
broken, and even large portions of them which have been lost
have been restored. The limb of the lizard when broken off
has grown again : a new foot been reproduced in crabs and
spiders ; in salamanders, a new eye and portion of the head
have been restored after the removal of the original parts by
amputation. Finally, earth-worms and many other annelides
can thus reproduce a great part of the body; and in the
hydra and fresh-water polyp (Fig. 4), a small fragment has
been found equal to the reproduction of the entire body.

§ 171. Moreover, various circumstances, which we have
not the leisure to examine here, may modify the progress of
the work of assimilation, render it active, retard it, or change
its direction. It is in this way that in certain diseases we see
nutrition to be almost entirely arrested, and that in others
certain tissues change their nature. It is also to be observed,
that this assimilative labour does not take place with the
same rapidity in all parts of the body ; to be assured of this,
we have only to observe the changes in form often brought
about by the progress of age ; for these changes depend
chiefly on this, that certain parts increase more rapidly than
others. Thus, from the moment of birth to the adult condi-
tion, the members of the body of man grow more rapidly than
the trunk ; whence it follows that, in general, this latter is a
portion the less considerable of the whole as the growth is
more prolonged.

90 ZOOLOGY.

§ 172. Excretion. — Whilst nutrition is going on, decom-
position proceeds pari passu, that is to say, the separation of
a portion of the molecules of the tissues, and their expulsion
from the body. The bones themselves are thus continually
decomposed and recomposed; the utricular tissue covering
the surface of the ligaments, mucous membranes, and
glandular cavities, is being continually renewed and de-
stroyed ; and the old epithelium gives way before new layers
formed beneath it in the substance of the tissues.

Some physiologists have thought that such a renewal of
the constituent parts of animal bodies affects every structure
and organ, and that an entire renewal of the body occurs in
every seven years. This opinion is not based on direct experi-
ment, and seems, indeed, contrary to the fact. Many organs
remain for long periods stationary, although it may be ad-
mitted that, under peculiar circumstances, the original tissues
themselves may be attacked, as after long fasting. Thus, the
curious experiments of M. Chossat show that when birds do
not find in their food a sufficient proportion of calcareous
matters, the phosphate of lime entering into the composition
of their bones is taken away, little by little.

Now, the blood furnishing, as we have seen, the materials
of the various humours which the animal economy constantly
rejects and expels from it by the route of the secretions,
becomes unceasingly impoverished, and might take away from
the organs the soluble principles they contain, if the repeated
introduction of foreign substances did not maintain this liquid
always saturated with the same principles. It results from
this, that this introduction of the alimentary matters into the
organism is necessary, not only to effect the increase of the
living parts, but to secure the conservation or preservation of
the tissues already existing, and to prevent the resorption or
re-absorption of their constituent materials. In brief, the
nutrient matter introduced continually into the blood is neces-
sary, no doubt, not only for the growth of the body, but
also to maintain all the organs in their integrity, and to pre-
vent their being acted on by absorption.

Finally, the slow combustion taking place in every part of
the body also destroys the combustible matters : and unless
this destruction be met by constant renewal, it would seem,
from the experiments of Dumas and others, that the oxygen
would act on and destroy the materials composing the organs
themselves. From the aliments there must come the com-

NUTEITIVE DECOMPOSITION. 91

bustible matters for the oxygen to act on, by means of which
they are transformed into carbonic acid gas and water, and in
that form eliminated from the body : from the same source
are derived the materials of growth and of secretion.

But whether the carbonated and hydrogenated matters
thus consumed come from the aliment directly or from the
tissues themselves, one thing is obvious, that the loss must
be supplied from without, under the form of aliments.

The alimentary matters, which contain only carbon, hy-
drogen, and oxygen in their ultimate composition, such as
fecuia or sugar, may be transformed into carbonic acid and
water, leaving no residue ; but the vital combustion of azotized
matters gives rise to other products ; and these compounds
by losing carbon become richer in azote, and constitute
peculiar organic principles, such as urea and uric acid.*

§ 173. Chemistry seems to prove that it is vegetables
which fabricate the combustible matters destined to be con-
sumed in animal bodies, plants alone having the power thus
to fix carbon under the forms of organic compounds.f

The carbonic acid gas and water escape by respiration ; the
more solid products, as the urea, by the urine. In the adult
animal it would thus seem that there may be found nearly
the whole of the elements introduced into the system by the
food or by respiratory absorption, in the products of the
respiration and urinary secretion, the alvine dejections being
composed almost wholly of the indigestible residue of the
food, mingled with various secretions.

Before the growth is completed, all the alimentary matter
is not burnt or consumed in this way ; a part is found in the
organism when the carbonaceous matters taken in exceed the
power of the oxygen to consume, the result being the deposi-
tion of fat, which may afterwards be consumed according to
the exigencies of the animal. J

* When the tartrate, malate, or citrate of potass has been absorbed or
injected into the veins, and, so absorbed, carbonate of potass is found in the
urine, thus proving the combustion of the vegetable acid entering into their
composition.

f According to the recent experiments of Dumas, Boussingault, and
Payen.

J The fat is not deposited indifferently in every part of the body. It is
composed of two substances, oleine and stearine, the proportions of which
vary in the fat of different animals. It is abundant in animals which hyber-
nate at the commencement of winter, but disappears towards the close of
that season. The fat is supposed to be useful as a cushion for certain organs,
as a reservoir to meet the consuming powers of the oxygen taken into the
body, and as a preservative of the heat of the body.

92 ZOOLOGY.

To complete this sketch of the phenomena of nutrition, all
that remains is to speak of the sources of animal heat.

OF ANIMAL HEAT.

§ 174 Animals vary so much in their different heat-pro-
ducing powers, that although all produce heat, some are
called cold-blooded animals with reference to others. The
difference may be shown by comparing the amount of heat
produced by a fish and a rabbit, placed in a vessel surrounded
with ice ; the quantities of ice dissolved will give the amount
of the difference, which is enormous ; for, after three hours,
the heat produced by the fish will scarcely have acted on the
ice, whilst that originating from the rabbit will have produced
more than a quart of water. Now the amount of heat
required to convert so much ice into water will be found
equal to that necessary to raise 'the temperature of three
quarts of water from the freezing to the boiling point.

Hence the distinction of animals into cold and hot blooded.
In man the heat of the skin varies from 97° to 100° Fahr. ;
that of the interior of the body is always 100°. It is the
same in most mammals. In birds the temperature rises to
108°. The blood in both is hotter.

Fig. 63.— The Marmot (Arctomys marmota).

§ 175. In general, birds and mammals maintain the
same temperature at all seasons of the year and in all climates;
but there are some in which the temperature lowers as winter
proceeds: these are the hybernating animals, such as the
marmot (Fig. 63), the bat, and hedgehog.

OF ANIMAL HEAT. 93

§ 176. In the young, the production of animal heat is not
equal to what it afterwards becomes, especially in those born
with the eyes closed. Thus kittens or puppies left exposed
to the air, even in summer, soon die. New-born children
also are extremely susceptible of cold.

§ 177. This production of animal heat is evidently con-
nected with the phenomenon of vital combustion, with the
absorption of oxygen by the blood, and the production of car-
bonic acid gas. It seems, in fact, to be proportional to the
amount of oxygen absorbed, and hence is greatest in birds
and mammals.

The production of carbonic acid gas takes place in the
capillary vessels, where, in fact, the arterial blood becomes
venous ; the production, then, of animal heat is not confined
to one spot, as the lungs, but is extended over the whole bod}'.
It depends on the arrival of fresh arterial blood, and when the
supply of this is cut off or diminished, the temperature is
immediately lowered.

There is a remarkable relation also between the richness of
the blood in solid parts and the production of animal heat.
It is richest in birds (14 or 15 : 100), in whom the animal
heat is greatest ; next in mammals (9 or 12 : 100) ; feeblest
in the cold-blooded, as in frogs and fishes, in whom the solid
parts of the blood, compared to the liquid or watery, is as 6
of globules to 94 of serum.

It bears a certain relation also to the distance from the
heart, and thus the limbs are most exposed to be frost-bitten.

Thus it is to respiration that is due the production of
animal heat, since it is in the lungs that the oxygen is ab-
sorbed. But in the higher animals this combustion itself is
evidently influenced by another physiological agent, of which
we have not }Tet spoken — the nervous system.

Numerous experiments have placed this fact beyond a
doubt. The late experiments of M. Bernard on the cervical
ganglions are in fact not opposed to this view. Toxic agents,
which lower the activity of the brain and nervous system,
obviously affect the production of animal heat.

§ 178. Hot-blooded animals have the faculty of resisting
external heat when raised above the natural temperature of
their bodies ; this is effected by evaporation from the surface
of the cutaneous transpiration, by which the temperature of
the body is maintained at nearly the same temperature at the
equator or within the polar circle.

94 ZOOLOGY.

II.— OF THE FUNCTIONS OF RELATION.

§ 179. Hitherto we have been occupied with those func-
tions which have for their object the preservation of the
individual ; let us now attend to those intended to make him
acquainted with surrounding objects.

§ 180. Observe carefully the movements of an animal,
and you will soon discover that some are obviously voluntary,
or directed according to the will of the animal. Another
class of movements may also be observed, over which the
animal does not seem to possess the same influence ; these
are the involuntary. These phenomena imply contractility
and volition ; but there is to be added another remarkable
faculty, sensibility, by which the animal perceives the pre-
sence of surrounding objects, and becomes conscious of their
presence.

These three faculties seem to be common to all animals ;
but there are others. Certain animals construct with the
most admirable art dwellings for their young and for them-
selves, and this they do independent of all instruction from
the parent. Others proceed on distant voyages and journeys,
traversing the air as certainly as if the point to be attained
were before their eyes. To this faculty the name of instinct
has been given ; it leads animals to perform certain acts
which are not the effects of imitation, and which are not the
result of reasoning. The phenomena are sometimes very
simple, and sometimes incomprehensibly complex.

To other beings are given the faculty of recalling previous
sensations, of comparing them with each other, analysing the
past and present, and drawing conclusions; these are the
intellectual faculties.

Finally, some animals can communicate to others a know-
ledge of the ideas they possess, by movements or sounds.

These varied phenomena, by which animals place them-
selves in relation with others, may be reduced to six principal
faculties, — namely, sensibility, contractility, will, instinct,
intelligence, and expression.

In the simplest animals, these various faculties of the life
of relation are not the appanage of any organ in particular ;
but in man and in the immense majority of animals, the
exercise of these faculties is dependent on the action of the
nervous system.

OF THE FUNCTIONS OF EELATION. 95

OF THE NEBVOTJS SYSTEM.

§ 181. This system is formed by a soft pulpy substance,
which is almost fluid in early life, but acquires more consis-
tence with years. The aspect of this tissue, called nervous,
varies much ; occasionally white, at other times grey or ash-
coloured ; in some parts it forms masses or ganglions, in
others elongated cords. The cords are called nerves; the
masses, ganglions or nervous centres.

§ 182. In man, and in those animals which approach him
in structure, the nervous apparatus is composed of two parts —
the cerebro-spinal or nervous system of animal life, the gan-
glionic or nervous system of organic life ; and each of these
systems is composed in its turn of two parts — a central, com-
posed of the nervous masses, and a peripheric, composed of
the nerves which proceed from these centres to all parts of
the body (Pig. 64.)

§ 183. Cerebro-spinal System in Man. — The central
portion of this system, also called the cerebro-spinal axis or
encephalon, is composed essentially of the cerebrum, cere-
bellum, and medulla spinalis, and is lodged in an osseous
cavity and canal, formed of the cranium and spinal column.

§ 184. Envelopes of the Encephalon. — Three membranes
enclose, support, and nourish the cerebro-spinal axis. The
first is the dura mater, a fibrous membrane of considerable
strength, adhering to several points of the osseous canal, and
forming a strong projecting covering for the encephalon. It
sends prolongations towards the interior of the cranium,
serving to protect various parts of the organ ; and in its sub-
stance are formed various venous canals or sinuses, in com-
munication with the general venous system of the body.
These sinuses are called sinuses of the dura mater.

Within the dura mater is a second membrane, called the
arachnoid. This is a serous membrane of extreme tenuity,
and transparent, but firm, and like all serous membranes, is
a sac without any opening into it. By one layer it invests
the inner surface of the dura mater, and by the other the
brain, thus providing for the movements of the organ.

Beneath the cerebral layer of the arachnoid is the pia
mater, immediately investing the nervous tissues itself. This
is a cellulo-vascular membrane, in which ramify the vessels
proceeding to and from the brain ; for the arteries especially
are, in general, minutely subdivided before they actually

Fig. 64.— Nervous System in Man, seen from behind, p. 97.*

OF THE NEBVOUS SYSTEM. 97

penetrate the nervous matter. These three membranes invest
the entire encephalon, and present thus a spinal as well as a
cranial portion.

§ 185. Though composed of several parts, the encephalon
may he viewed as one ; yet each division seems to perform
distinct functions, in a certain sense.

§ 186. The cranial portion is composed of the brain, cere-
bellum, and pons Varolii ; the spinal portion may be viewed
as composed of the medulla oblongata and spinal marrow,
properly so called.

The brain (Fig. 64 a, Figs. 65, 66 a b c) (cerebrum) is by
much the largest part ot the encephalon in man and mammals.
The form of the skull, in a general way, represents its shape,
more especially in man. The cerebrum proper is subdivided
into two hemispheres by a deep mesial fissure, extending quite
down to the corpus callosum in the middle, and anteriorly
and posteriorly separating the hemispheres completely from
each other. The corpus callosum unites the hemispheres, and
may be called a transverse commissure. In the fissure descends
the falx cerebri, a partition formed by the dura mater. On
the surface of these hemispheres may be seen the convolutions
and anfractuosites of the brain so distinct in man, and
which have given rise to so much speculation. They are of
little depth in very young children and in most animals.

By turning up the brain and examining its base, it is easy
to observe, without much dissection, that the brain admits of
being divided into three lobes on each side, an anterior,
middle, and posterior ; this last is not so distinct as the
others.

[In point of fact there is no very obvious distinction between
the middle and posterior lobes, and it would have been much
better had anatomists divided the inferior surface of each hemi-
sphere into two lobes only, an anterior and posterior. Thus
would have been avoided those silly disputes which have lately
occupied the attention of the public about the size and form of
the brain in apes as compared with the human brain. The great
distinction between the latter and other vertebrate animals is
that in man, the posterior lobe of the cerebrum overlaps the

* a, cerebrum ; b, cerebellum ; e, spinal marrow ; d , facial nerve ; e, brachial
plexus caused by the union of several nerves coming from the spinal mar-
row ; f, median nerve ; g, cubital nerve ; h, internal cutaneous nerve of the
arm; i, radial and musculo- cutaneous nerve of the arm; ^intercostal nerves ;
k, femoral plexus; I, sciatic plexus; mt tibial nerve; n, external peroneal
nerve ; o, external saphenous nerve.

H

98

ZOOLOGY.

cerebellum, whilst in other animals (with scarcely an exception)
it does not. But the brain in all mammals is formed on precisely
the same ^)lan ; no parts have been left out. — R. K.]

7 9 10 11 6 e

Fig. 65.— Section of the Brain, Cerebellum, Pons, and Medulla
Oblongata.*

* Vertical section of the cerebrum, cerebellum, pons Varolii, and medulla
oblongata ; a, anterior lobe of the brain ; b, middle lobe ; c, posterior lobe ;
d, cerebellum ; e, medulla spinalis ; f, section of the corpus callosum. The
lateral ventricles of the brain are situated on either side of the corpus callo-
sum, which assists in forming their upper wall, g, optic lobes : 1, olfactory
nerves ; 2, the eyeball, from which may be traced the optic nerve as far as the
optic thalami or lobes. Close to this is the nerve of the third pair. 4, the

proceeding to the abducentes muscle ; 7, facial nerve; — under the origin of
this nerve may be seen a portion of the acoustic ; 9, nerve called glosso-
pharyngeal ; 10, pneumogastric nerve ; close to it is, 12, the spinal acces-
sory ; these three nerves, the glosso-pharyngeal, pneumogastric, and spinal
accessory, are hy some reckoned as one pair ; 11, the ninth pair of some,
and the eleventh of others, called also hypoglossal ; 14 and 15, cervical nerves.

OF THE NEEVOUS STSTEM. 99

It is on this surface also that the cerebellum may be dis-
tinctly seen, the so-called pons, and the large masses of
fibres called crura uniting the pons to the hemispheres of the
brain; here also may be seen all the cerebral or cranial nerves,
as they proceed to or from the brain ; the large arteries like-
wise, which all reach the cerebral portion of the encephalon
by the base. The two little rounded eminences seen here are
called mammillary eminences.

The grey matter of the brain is found chiefly on the surface,
and the white, medullary or fibrous in the interior, but not
uniformly so. The ventricles of the brain (Fig. 65) all com-
municate with each other, directly or indirectly.

§ 187. The cerebellum is placed under the posterior part
of the brain, and is separated from it by the tentorium, a par-
tition formed by the dura mater. It also is composed of two
hemispheres, and a mesial portion connecting them together.
On the surface of the cerebellum there are no convolutions,
but the margins of laminae or plates, of which the cerebellum
is composed. It is connected with the medulla spinalis,
the pons, and cerebrum by peduncles of medullary fibres
called crura. In volume it is about one-third of the cere-
brum, and is larger comparatively in the child than in the
adult.

§ 188. Optic Lobes. — By removing the upper portion of
the hemispheres and the corpus callosum, the ventricles of the
brain are exposed ; also certain rounded masses, forming as it
were the base of the section. These masses, named in suc-
cession from before backwards, are the corpora striata, the
thalami nervorum opticorum, and the tubercula quadri-
gemina ; and on the back and somewhat lower part of the
thalami may be seen, by raising the thalami upward, certain
rounded elevations of a greyish colour ; these are the corpora
geniculata. On all these structures important experiments
have been made in living animals.

§ 189. Spinal Marrow ; Medulla Spinalis. — The
medulla spinalis (Fig. 64 <?; Fig. 66/1), may be viewed as a
continuation of the medulla oblongata and that of the brain
itself. A median fissure of no great depth divides it into
• two lateral portions, anteriorly and posteriorly. Its upper
extremity, which is enlarged, is usually called the bulb, by
others the medulla oblongata : here are to be seen various
swellings called olivary, pyramidal, and restiform bodies ; and
at the sides of this medulla oblongata and of the spinal

H2

100

ZOOLOGY.

10
11
13

9
25

marrow following it, may be seen
proceeding outwards the spinal
nerves. No nerves come from or go
to the cerebrum proper, unless it
be the olfactory. Where the nerves
leave the spinal marrow to proceed
to the pectoral extremities, the organ
is usually enlarged ; and the same
occurs, but not so distinctly, lower
down, where the nerves leave to
proceed to the pelvic extremities.
In man, the spinal marrow descends
only as low as the second lumbar
vertebra, terminating in a fine
thread-like body, by which it is
attached to the lower part of the
column. The inferior portion of the

* The cerebrospinal axis seen anteriorly :
the nerves have been cut through at a short
distance from their origin or central termi-
33 nation : — a, the cerebrum ; b, anterior lobe
of the left hemisphere of the brain ; c, middle
lobe ; d, posterior lobe, almost concealed by
the cerebellum ; e, the cerebellum ; ft the
medulla oblongata or bulb ; 1, first, or ol-
factory pair of nerves; 2, second pair, or
, optic ; 3, third pair, or motores oculorum ,
4, fourth pair, or pathetic ; 5, the facial, or
i fifth pair : 6, sixth pair, or abducentes ;
7, nerves of the seventh pair, or facial ; also
the acoustic or portio mollis, by some called
the auditory, and viewed as a division of the
k seventh; others call them the eighth pair;
9, the glosso-pharyngeal nerves, called the
ninth pair by some, by others the anterior
division of the eighth pair ; 10, tfce pneumo-
gastric, by some included in the eighth pair,
by others called the tenth pair; 11, nerves
of the eleventh and "twelfth pairs, the first
being viewed by some as a division of the
/ eighth pair, and called spinal accessory;

TV «/. n v, • i » • • t-ne latter, called by some the ninth, by
Fig. 66. Cerebro-spmalAxis.* others the twelfth, is the motor nerve of
the tongue ; 13, nerves of the thirteenth pair,

or sub-occipital; 14, 15, 16, the first, second, and third pairs of cervical
nerves; g, cervical nerves forming the brachial plexus; 25, one of the
pairs of nerves of the dorsal portion of the spinal marrow ; 33, one of the
pairs of lumbar nerves ; h, lumbar and sacral nerves forming the plexus
whence come the nerves of the lower extremities ; i andj, termination of the
spinal marrow, called cauda equina ; k, great sciatic nerve proceeding to the
lower extremities.

OF THE NERVOUS SYSTEM. 101

spinal canal, lumbar, sacral, and coccygeal (where it is quite
imperfect), is occupied with the membranes and by the nerves
proceeding from the spinal marrow. This assemblage of nerves
within the canal was called by the older anatomists the cauda
equina, in the centre of which will be found the terminating
filum or thread of the organ itself.

The spinal marrow is composed, like the brain and cere-
bellum, of a medullary and cineritious portion ; but here the
grey matter is central and the medullary external. A fluid,
clear and limpid, discovered by Cotunni, a distinguished
Neapolitan physician, fills up the space intervening between
the arachnoid membrane and the pia mater, by means of
which, no doubt, this extremely delicate organ is protected
from shocks and other injuries.

§ 190. Structure of the Encephalon. — The organ is
composed of two distinct substances, the cineritious and
medullary ; this latter is fibrous, and to the tracing its
fibres anatomists have in all ages given the greatest atten-
tion.

By commencing with the spinal marrow, and tracing its
fibres upwards, it will be found that it is composed of two
halves, united to each other by transverse medullary fibres.
These halves are each composed of six medullary bands or
columns, of which four occupy the anterior surface, two the
posterior. The four anterior ones may be traced upwards
into the corresponding pyramidal and olivary bodies, pro-
ceeding from thence into the brain itself; the two posterior
proceed, we shall find, to the cerebellum. To return to the
olivary and pyramidal fasciculi: we observe, first, that a
portion of those on the right side cross to the left, and those
from the left to the right column, thus decussating with each
other. After this decussation, they plunge into the annular
protuberance (pons Yarolii), and, continued forwards, con-
stitute the crura cerebri. The fibres from these ultimately
expand in the convolutions of the anterior and middle lobes
of the brain. The. longitudinal fibres of the olivary fasciculi
ascend like those of the pyramids, and passing through the
pons form the inner and posterior parts of the peduncles of
the brain ; during their course they traverse several masses
of the cineritious substance, increase in size, and finally pass
into or form various parts of the brain, as the thalami optici
and corpora striata; finally, they expand into the cerebral
convolutions. Several transverse commissures, as the corpus

102

Fig. 67. — Superior Portion of the Ganglionary System.*

* This wood engraving, copied from M. Sappey's Treatise on Human
Anatomy y represents the principal nerves of the neck, as well as the ganglions

OF THE NERVOUS SYSTEM.

103

callosum, and anterior and posterior commissures, connect
the two sides of the brain with each other.

The posterior columns of the medulla oblongata (restiform
bodies) unite with some fibres coming from the neighbouring
portions of the medulla spinalis, and thus constitute the
crura cerebelli, or crura ad medullam
oblongatam ; these fibres plunge into the
centre of the cerebellar hemispheres, and
assist in forming the central medullary
mass, which being invested with cineritious
matter, forms that remarkable assemblage
of laminae to which anatomists give the
name of arbor vitse, seen on making a
section of either hemisphere of the cere-
bellum. Thus the cerebellum receives
crura or peduncles from three sources,
viz., the pons, the medulla oblongata, and
the tubercula quadrigemina.

§ 191. Nerves. — The nerves originating, or as some view
it, terminating, in the encephalon, amount to forty-three pairs
(see Fig. 64 and Fig. 66) ; they are reckoned numerically
from before backwards. The first twelve pairs arise within
the cranium, and leave the cavity by apertures in the cranial
bones ; the thirty- one pairs which follow arise from the spinal
marrow, and leave the osseous canal by openings called
intervertebral, as being placed between the vertebrae.

Each of these pairs of nerves is formed of a great number
of filaments, enclosed in a neurilemma. These elementary
fibres are extremely fine ; they do not unite with each other,
but pass from the central extremity of the nerve to the peri-

of the neck and thorax belonging to the sympathetic system of nerves. —
1, pneumogastric nerve, the principal branches of which form plexuses with

10, 11, cardiac branches proceeding to the heart ; 13, pulmonary plexus ;
14, lingual nerve ; 15, terminal portion of the great hypoglossal ; 16, glosso-
pharyngeal nerve ; 17, spinal accessory of Willis ; 18, cervical nerve of the
second pair of spinal nerves ; 19, third cervical pair ; 23, 26, 27, 28, pairs of
cervical nerves, uniting with the first dorsal to form the brachial plexus ;
24, superior cervical ganglion of the great sympathetic ; 25, middle cervical
ganglion ; 26, inferior cervical ganglion ; 27 to 30, dorsal ganglions.

* A portion of the spinal marrow. — a, medulla spinalis ; b, posterior root
of one of the nerves ; c, ganglion situated on this root ; d, anterior root of
the same nerve, about to unite with the posterior root after this latter has
passed the ganglion ; e, common trunk formed by both roots ; f, small
branch proceeding to anastomose with the great sympathetic.

104 ZOOLOGY.

pheral. At their origin, the fibres composing the nerve are
called roots, and are grouped in the spinal nerves into anterior
and posterior roots.

On the posterior root is a ganglion through which the
filaments pass, and then unite with the anterior root. On
certain of the cranial nerves, some of the roots also have
ganglions. Experiment has shown that the posterior roots
are nerves of sensation ; the anterior, nerves of motion : when
nerves unite with each other by what is called anastomosis*
(although they do not really unite, but merely exchange
fibres), there results what is called a plexus.")" Finally, in
the various organs the nerves seem to terminate by forming
wide plexuses or loops.

§ 192. Ganylionary System. — This system — which has
also been called the nervous system of organic life, the sys-
tem of the great sympathetic, &c. — is composed of a certain
number of small masses of nervous matter, united to each
other by filaments of communication, and by the same means
to the nerves of the cerebro- spinal system. From these,
ganglions, nerves proceed to numerous vital organs, and are
supposed also to follow the course of all the great blood-
vessels.

The ganglions composing this system are arranged in a
double column on each side the spine, anteriorly, from the
first vertebra to the last; but many others are scattered
through the viscera. They are not found in the limbs. A
broad distinction which exists between the cerebro-spinal
nerves and the ganglionary is, that the former proceed to the
skin, organs of sense, muscles, &c. ; the latter to the vital
organs, as the heart, intestines, liver, kidneys, &c. : the
former are nerves of relation ; the latter have more a reference
to nutrition.

§ 193. Nervous System of other Animals. — In all ani-
mals, birds, fishes, and reptiles, the arrangements of the
nervous system are much as in man.

But in the invertebrata it is not so ; in these *the cerebro-
spinal axis seems wanting, and all the nerves of the body
seem to reunite in certain ganglions more or less apart from
each other (Fig. 68). Finally, in the great division of the
zoophytes, there remains only a vestige of a rudimentary

* It is not then a true anastomosis.

t Plexus, from plecto (I intermingle) is a term applied also to the blood-
vessels, and means merely a sort of network.

OF THE NERVOUS SYSTEM. 105

nervous system, and even this seems to be occasionally entirely
absent. In speaking of these various groups of animals, the
peculiarities here adverted to will be noticed.
Let us now consider the functions of the system.

§ 194. Sensibility is the faculty to receive impressions,
and to have a consciousness of
them. It belongs to all animals,
but in different degrees. As we
ascend in the zoological scale, the
sensations become more and more
varied, the knowledge acquired
through them greater, the nervous
system more complex.

§ 195. In the lowest class of
animals, the structure is at first
very simple, and their sensations
do not seem very distinct. In the
earth-worm, a knotted cord extends
throughout the whole length of
the body, and to and from these
knots or ganglions the nerves pro-
ceed; but each of these parts seems Fig 68._Nervous System of
equal to every other, and there is an Insect (Carabus of the
no specialization of any. This gardens). A Beetle,
simplicity of structure gives way
to a form more complex as we ascend in the animal scale.

§ 196. Functions of the Nerves. — All parts of the body
are not equally supplied with nerves, and there are parts
which seem to have none. Hence, no doubt, is the fact that
whilst some parts are extremely sensitive, others are but little
so, or wholly insensible. No experiments are required to
show that a part owes its sensibility to the contiguity of the
nerve which connects it with the central organs of the nervous
system. The nerves, then, are not the organs by which the
sensations are perceived ; they merely transmit them to the
central system, where all perception resides.5*

§ 197. Where, then, is the seat of the faculty of percep-
tion ? Which is the perceiving organ ?

§ 198. Influence of the Encephalon. — Does perception
reside in the spinal marrow, the cerebellum, or the cerebrum ?

* It is now certain that perceptions or impressions on the central organs of
the nervous system are of two kinds ; one attended with consciousness, the
other without. — R. K.

106

ZOOLOGY.

Experiments on living animals, surgical operations, and acci-
dents, have repeatedly proved that the seat of perception is
not in the spinal marrow. The cutting this across in a living

Fig. 69.— A, Brain of the Cod. B, Brain of the Shark.

animal merely destroys the sensibility, and paralyzes the
movements of all the parts supplied with nerves from it helow
the point divided.

With the brain it is quite otherwise. The surface of the
brain and its substance generally, may be cut or irritated in
a living animal without it being sensible of any injury or
pain; but remove it, and the whole body of the animal

Fig. 70.— Brain of the Sparrow.

instantly becomes insensible. The action of the brain is as
essential in the perception of sensations as for the acts of
volition.

§ 199. The insensibility of the brain when cut or rudely
touched is a remarkable circumstance, long known, however,
to surgeons. But the faculty of perceiving sensations caused

OF THE NERVOUS SYSTEM,

107

by impressions on the organs resides in it; and it would
seem, from Flourens' experiments, to reside more especially
in the hemispheres of the cerebrum, to which the sensations
are transmitted by the nerves.

§ 200. Neither ought it to be forgotten that each nervous
fibril is quite distinct from one extremity to another ; and to
this must be ascribed the distinctness in our sensations, and

Fig. 71. — Brain of the Korqual (Balsenoptera rorqual). Figure A
gives the upper surface j figure B the lower.

the referring them always to their peripheral extremities.
After amputation, the pains which occasionally continue are
constantly referred to the foot or hand which is no longer
present.

§ 201. Nerves of Sensibility or Sensation. — All nerves
have not the power of transmitting sensations to the brain ;
some, on the contrary, are clearly nerves of motion, whether
acted on by our will or excited by other means. Some nerves,
as the optic, transmit only the impressions received from
colours ; to other stimulants this nerve is insensible.

§ 202. Modifications of the Sensibility. — To these modi-
fications of the sensibility we owe the five senses ; 'the senses
of touch, taste, smell, hearing, seeing, are so many distinct
faculties putting us in relation with the various qualities of
the external world. To the first pair of nerves belongs the
sense of odours ; by the second pair we perceive coloured
bodies ; the portio mollis of the seventh pair, by some called

108 ZOOLOGY.

the eighth pair, is the instrument by which the sensation of
sounds is conveyed to the brain ; and by means of a branch
of the fifth pair we perceive the sapid qualities of objects ;
whilst the spinal nerves distributed to the fingers and toes,
endow their extremities with fine tactile powers.

§ 203. The roots of the spinal nerves being double, a
double function had been long suspected; this was put
beyond dispute by Bell and Magendie,* who showed that by
the posterior roots the sensations travel to the brain, whilst
by the anterior the power of motion travels to the muscles.
Some differences have been observed in various parts of the
spinal marrow ; the sensibility is acute in the dorsal aspect of
the organ, and much more feeble anteriorly.

[Some recent experiments performed by M. Brown-S^quard
raise doubts as to the correctness of this view when taken too
exclusively, but they do not affect the chief results. — R. K.]

§ 204. Ganglionary System. — This system is but little,
if at all, sensible to ordinary stimulants : neither cutting nor
pinching affects it. In the healthy state, the organs to which
the nerves of this system proceed are in like manner but little,
if at all, sensible; but when diseased, their sensibilities
become highly exalted.

§ 205. Special Organs of tlie Senses. — The apparatus of
the sensibility is not composed only of the different parts of
the nervous system whose uses we have already pointed out ;
the nerves furnished with the faculty of transmitting to the
brain the sensations reaching us from without, do not termi-
nate freely in the exterior, so as to receive directly the con-
tact of the producing agents of our sensations, but terminate
in positive instruments destined to collect, so to say, the exci-
tation, and to prepare it in such a way as to assure its action.
These instruments are the organs of the senses, and it is
essentially by the intermedium of these^rgans that the sen-
sations reach us; but they are not indispensable for the
exercise of all these faculties : the tactile sensibility may be
called into play everywhere where nerves exist adapted to
conduct the ordinary sensations, and it is only by the special
senses, that is to say, by the taste, smell, hearing, and sight,
that this intermediate organ between the nerve and the
external world is a necessary condition.

* First by Mr. A. Walker.— K. K.

OF THE SENSE OF TOUCH. 109

Having studied in a general way the phenomenon of the
sensibility, as well as the organs which are its seat, we ought
now to examine more in detail each of the forms under which
this property is manifested, or in other words, enter on the
particular history of each of the senses with which nature
has endowed animals.

OF THE SENSE OF TOUCH.

§ 206. All animals possess a tactile sensibility more or
less delicate, and it is especially by the intermedium of the
membrane with which the surface of their bodies is covered
that this faculty is exercised. To study it, it is, then,
above all necessary to examine what is the structure of the
skin.

In man, the external surface of the body, and that of the
cavities hollowed out in the interior, but communicating
externally, such as the digestive canal, &c., are clothed with
a tegumentary membrane more or less thick, and quite
distinct from the parts which it covers. This membrane is
everywhere continuous with itself, and in reality it forms but
a continuous whole; but its properties are not everywhere
the same, and it is called by different names when it is
reflected internally to line the interior cavities, or when it is
extended over the outer surface of the body. The internal
portion of the general tegumentary membrane is called
mucous membrane, and the external portion skin.

§ 207. Structure of the Skin. — Two principal layers
compose the skin : the dermis or true skin, and the epidermis
or scarf skin.

The dermis forms the deeper and thicker layer of the in-
teguments. It is a strong, supple, elastic membrane, whitish,
and very resistant. A great number of fibres may be seen
in it, crossing each other in all directions. Beneath it is a
dense layer of cellular substance connecting it to the subja-
cent parts, and in this sometimes fleshy fibres are found. On
its surface may be seen, especially in the palms of the hands
and extremities of the fingers, the elevations, called papillae,
arranged in regular rows. Of the dermis of animals leather
is made.

The epidermis is a kind of insensible varnish laid over the
sensitive skin beneath. It is a tissue composed of dried-up
utricles, which form on the surface of the dermis, and which

110 ZOOLOGY.

harden only by being exposed to the air. It is composed of
several layers, of which the lower or deepest layer, being soft
and containing the pigmentary matter giving the colour to
the skin, has been viewed and described by some physiologists
as a distinct membrane, under the name of retemucosum. In
man, and in many animals resembling him, the epidermis is
cast off in the form of small scales, which are constantly
renewed. In serpents, the entire epidermis is cast off as a
slough.

The pores of the skin correspond to the summits of the
papillse just described. They give passage to the perspiration
or sweat, an acid liquid formed by secretion, and which must
not be confounded with the insensible perspiration. These
pores, exceedingly minute, do not traverse the skin ; they are
merely the orifices of the excretory canals of so many small
ampullae lodged in the substance of the skin, and which are
the secreting organs of the sweat.

Other larger orifices are found on the surface of the skin ;
some for the passage of the hairs, and others for the escape of
a fatty matter secreted by follicles lodged in the substance of
the skin. These are called sebaceous glands or follicles.

§ 208. The principal use of the epidermis is to throw
obstacles in the way of evaporation, and to protect the sensi-
tive skin beneath. It deadens more or less all impressions,
and hence its thickness on the heel and sole of the foot
generally : it thickens whenever it is exposed to friction.
Finally, in some animals it becomes encrusted with calcareous
matters, becoming then altogether inflexible, and rendering
the surface of the body insensible.

§ 209. The sensibility of the skin resides in the dermis
and depends on the nerves of touch distributed to the
papillae.

§ 210. Special Organs of Touch. — Tactile sensibility is
spread over the whole body, but it is in the extremity of the
fingers alone that the true power of touch resides. The hand,
of course, is especially made for the exercise of this faculty.
The delicacy of the integuments, the length of the fingers,
and the opposing thumb, all contribute to this effect.

In most animals these organs are not so favourably
arranged : nevertheless, the proboscis of the elephant is a
wonderful tactile instrument. There are animals which em-
ploy the tongue for this purpose, and others are provided with
palpi, tentacula, &c. (Figs. 9, 10).

OF THE SENSE OF TASTE. Ill

§ 211. By touch we appreciate most of the physical pro-
perties of bodies, such as their dimensions, form, temperature,
consistence, polish or the opposite, weight, movements, <fcc.
Some philosophers have adopted exaggerated ideas of the
importance of this sense to human intelligence, for which
there is not the slightest occasion.

OF THE SENSE OF TASTE.

§ 212. By this sense we discover the savours of
bodies.

§ 213. Certain bodies are extremely sapid, others but
little, and some not at all. The cause of these differences is
quite unknown ; but, generally speaking, insoluble bodies are
not sapid, and when the tongue is dry and parched the taste
is not perceived.

§214. By taste most animals distinguish their food ; and
hence, no doubt, the reason why the instrument is placed at
the entrance of the digestive tube. The tongue is the prin-
cipal seat of taste ; but other parts of the mouth possess the
power of perceiving certain savours. The mucous membrane
which covers the tongue of man is sufficiently well supplied
with bloodvessels and nerves supplying papillae of various
forms — lenticular, fungiform, and conical. The tongue itself
is muscular, and receives branches of motor and sentient
nerves. A branch of the fifth pair is the gustatory ; it is
sometimes called lingual.

§ 215. If this nerve be cut in the living animal, the sense
of taste is destroyed, but the movements of the tongue
remain ; if divided within the cranium, the sense of taste is
destroyed all over the interior of the mouth.

The section of the hypoglossal nerves destroys the motion
of the tongue and of all other parts to which these nerves
proceed. The sense of taste remains unaffected. The
glossopharyngeal, distributed chiefly to the pharynx, and
which are sensitive nerves, have also some gustatory
powers.

§ 216. The tongue has nearly the same structure in all
animals ; but in birds it is generally cartilaginous, and without
nervous papillae; accordingly, their sense of taste is con-
sidered as obscure. It is much the same in fishes ; and in
the lower animals, the faculty seems to be exercised by all
the interior of the mouth.

112

ZOOLOGY.

OF THE SENSE OF SMELL.

§ 217. Odours are produced by particles of extreme
tenuity, which escape from odorous bodies, and spread
through the air like vapours. The quantity requisite of
some of these odorous matters powerfully to affect the smell
is extremely small : a morsel of musk, for example, will per-
fume the air of a room for a considerable time without losing
its weight. Some bodies imbibe vapours and become odorous

in their turn, such as clothes
and water ; but others resist
their passage altogether, such
as glass. Odours may be
perceived at a great distance,
but the odorous particles
must always come in contact
with the organs. For this,
the mechanism of smell is
analogous to that of taste
and touch, whilst in sight
and hearing it is quite other-
wise.

§ 218. As the air is the
ordinary vehicle of odours,
the organ perceiving them is placed at the entrance of the
respiratory tubes. In man, as well as in mammals, birds,
and reptiles, the nasal fossae are the seat of the sense of
smell.

§ 219. These fossae communicate with the exterior by the
nostrils, and open behind into the pharynx. They are separated
from each other by a vertical partition : their walls are
formed by various bones of the face, and by the cartilages of
the nose. On the external wall of each may be seen three
prominent laminae, curved on themselves ;•(" they are formed
by the turbinated bones ; and by being rolled on themselves
they thus extend considerably the pituitary membrane, which
invests them. Upon this membrane the olfactory nerves are

* Vertical section of the nasal fossae, representing the outer wall of the
left nasal fossa. — a, the mouth ; d, portion of the base of the cranium ;
e, forehead ; m, sphenoidal sinus ; n, opening of the Eustachian tube; o, pen-
dulous palate. The frontal sinuses do not exist in young persons, but with
age they often acquire considerable dimensions, as do the sphenoidal sinuses.
They are generally small in women.

t That is, twisted in a spiral manner, like a univalve shell.

Fig. 72.— Nasal Fossae in Man.*

OF THE SENSE OF HEARING. 113

distributed. Finally, between these turbinated bones there
are longitudinal grooves, called meatuses. These fossae com-
municate with cavities, called sinuses, hollowed out in
the thickness of the frontal bone, the superior maxillary, &c.
The pituitary membrane is thick, and has a velvety appear-
ance ; on its surface may be observed a vibratile movement,
produced by microscopic cilia ; finally, it is continually mois-
tened by a viscous liquid, called nasal mucus, and it receives
many nervous filaments from the olfactory and fifth pair of
nerves.

§ 220. The membrane must be moist, in order that odours
may be perceived ; and the sense is strongest in the upper
part of the nostril. The extent of membrane seems greatly
to influence the power of the organ ; and in this respect the
carnivora, the ruminants, and some pachydermata, are re-
markable for the development of the turbinated bones, and
consequently for the extent of mucous membrane covering
them. In reptiles the organ is extremely simple.

§ 221. In fishes, the nasal fossae do not communicate
with the pharynx, but are merely cavities shut in at the
back, and the pituitary membrane presents in them a num-
ber of folds, arranged like rays around a central point, or
in parallel rows like the teeth of a comb, on each side of a
median band.

But there are many animals which have a fine sense of
smell, as insects, Crustacea, and mollusca, and in which no
special organ of smell has ever been discovered.

OF THE SENSE OF HEARING.

§ 222. The apparatus of hearing is very complex, minute,
and difficult to describe, and its essential part is enclosed
within the petrous portion of the temporal bone (Fig. 73 e).

We divide the ear of man into three portions — the external
ear, the middle ear, and the internal ear. The external ear is
composed of the pavilion or figured part of the ear, and the
auditory canal.

The figured part of the ear is composed of a fibro- cartila-
ginous lamina, adhering to the edge of the auditory canal, and
covered with a very fine and thin skin, dry and tense, and is
so arranged as to form an acoustic tube. The lobe of the ear
is not supported by any cartilage. The auditory tube is
partly cartilaginous and partly osseous ; the integuments
I

114

ZOOLOGY.

pass into it, and terminate by a cul-de-sac over the drum of
the ear. It is in this tube or canal that we find the small
sebaceous follicles which secrete the cerumen — that is, the
wax of the ear.

Tc h g e" e" f e' b

Fig. 73. — Auditory Apparatus in Man.*

The middle ear is composed of the tympanum, of the cavity
of the tympanum, and parts connected with it.

The cavity of the tympanum is a cavity of an irregular form,
hollowed out in the substance of the petrous part of the tem-

* Vertical section of the auditory apparatus, somewhat magnified as respects
the deeper structures. — a, external ear ; I, lobe of the ear ; c, the eminence
called antitragus; d, concha, continuous with the external auditory canal (f) ;
ee, petrous part of the temporal bone ; e , mastoid process ; e", articular or
glenoid cavity for the condyle of the lower jaw; e", styloid process of the
temporal bone ; e'"f, extremity of the canal by which the internal carotid
artery passes into the interior'of the cranium ; f, auricular canal ; g, mem-
brana tympani ; h, cavity of the tympanum ; the ossicula auditus have been
removed ; i, opening in the wall of the tympanum leading to osseous cells ;
the fenestra ovalis and rotunda are close to this opening : Jc, Eustachian
tube; £, vestibule ; m, semicircular canals ; «, cochlea; o, acoustic nerve.

OF THE SENSE OF HEARING. 115

poral bone, and separated from the auditory canal by the mem-
brane of the tympanum. Opposite to this membrane are two

" f

'' \

lob

Fig. 74.— Tympanum and Ossicula Auditus.*

openings, called the fenestra ovalis and fenestra rotunda. In
the back wall of the cavity is an opening leading to the mastoid
cells ; and inferioiiy may be seen the opening of the Eusta-
chian tube, leading to the nasal fossaB, and thus admitting the
external air into the cavities of the middle ear. Finally, this
cavity is traversed by a chain of small bones, extending from
the drum of the ear to the bottom of the fenestra ovalis,
where it touches by the base of the stapes the membranous
vestibule.

The bones are four in number, and are called the malleus,
incus, lenticular bone, and stapes. A small stalk belonging to
the malleus rests on the drum of the ear. Finally, small
muscles attached to these bones augment or diminish the
tension of the chain.

The internal ear is also enclosed within the petrous part of the
temporal bone. It is composed of three parts : the vestibule,

* Kepresents the cavity of the tympanum, the ossicula auditus, and their
muscles, magnified. — a a, cavity of the tympanum; b, membrana tympani, or
rather the osseous circle to which it is attached; c, handle of the malleus,
resting on the middle of the membrana tympani ; d, head of the malleus
articulating with the incus ; e, long handle of the malleus, passing into the
glenoidal fissure ; the anterior muscle of the malleus is attached to it ; f, in-
ternal muscle of the malleus ; g, anvil ; h, lenticular bone ; i, stapes ;
k, musculus stapedius. •

i 2

116 ZOOLOGY.

the semicircular canals, and cochlea. The vestibule is in the
middle, and communicates with the tympanum by the fenestra
ovalis. The semicircular canals (m) are three in number, and
are rounded osseous and membranous tubes. Finally, the
cochlea (n) is a single organ, resembling the shell of the
whelk ; its cavity is divided into two parts
by a longitudinal partition, half osseous,
half membranous, and communicates with
the interior of the vestibule and with the
tympanum by the fenestra rotunda. The
internal ear is osseous and membranous,
containing a watery fluid, and, even in
man, some remains of a semi-solid body,
analogous to the vitrine of the eye. The
auditory nerve enters the petrous part of the
temporal by the internal auditory canal, and
terminates in the interior of the membranous
pouches of the vestibule, semicircular
canals, and cochlea. On its integrity depends the sense of
hearing.

§ 223. Mechanism of Hearing. — Sound is the result of
a very rapid vibratory movement which the particles of
sonorous bodies experience when struck. The undulations of
the sonorous body are communicated to the air which is in
contact with it, and are thus propagated to a distance. To
be audible, they must reach the fluid which immediately
bathes the acoustic nerve.

§ 224. The sonorous vibrations first strike the external
ear ; by it they are reflected and strengthened, and directed
towards the middle ear by the auditory passage ; but in man,
probably from the smallness of the external ear, the loss of it
does not greatly affect the hearing. The vibrations excited
in the external ear pass internally by the walls of the canal,
but chiefly through the air which fills tEe canal, and so reach
the middle ear.

§ 225. The membrane of the tympanum is the chief agent
in facilitating the transmission of the sonorous vibrations of
the external air towards the acoustic nerve ; this has been
proved by many experiments.

§ 226. The vibrations are transmitted from the membrane
of the tympanum to the small bones of the ear, to the walls

^ * a, the malleus ; 6, the incus; c, the lenticular bonej d} the stapes.

OF THE SENSE OF HEARING. 117

of the cavity, and to the air it contains, and thus they reach
membranes stretched over apertures leading to the internal
ear. Now the posterior surface of these membranes is in con-
tact with the aqueous liquid filling the internal ear, and in
this liquid are suspended the membranous pouches, which, in
their turn, are filled with another liquid, into which plunge
the terminating filaments of the acoustic nerve. Thus the
vibrations reach the nerve itself by which the sensation is
communicated to the brain.

§ 227. The air contained in the cavity of the tympanum
seems to play an important part in the phenomena of hear-
ing, for it has been observed that when the Eustachian tube
has been closed by disease, deafness is almost sure to follow.
But the integrity of the drum of the ear is not so essential
for the due performance of the function.

§ 228. However important the chain of small bones of
the tympanum may be in moderating the intensity of sounds
striking the drum of the ear, or by assisting in its tension so
as to enable us to perceive remote or feeble sounds, certain it
is that the loss of the hammer, the anvil, and lenticular bone
does not necessarily cause the loss of hearing, which however
is said to be sure to happen when the stapes has also been
lost.

§ 229. Admitting that all the parts just described serve
to perfect the ear of man, it must also be admitted that they
are not all essential to the organ as an instrument of sense.
They also gradually disappear as we descend the scale of
beings. Thus, in birds, we have no longer an external ear.
In reptiles the external auditory canal also disappears ; the
drum of the ear becomes external, and the cavity of the tym-
panum simplified; finally, in most fishes every vestige of
an external ear and a middle ear disappears, and the apparatus
of hearing is composed of a membranous vestibule, surmounted
by three semicircular canals, furnished below with a small
sac, which seems to represent the cochlea, the whole being
suspended in the lateral part of the great cavity of the cra-
nium.

In animals placed still lower in the scale, we find, also dis-
appearing, the cochlea and semicircular canals, the structures of
which we know not the use ;* but the membranous vestibule

* According to the experiments of M. Flourens, it would seem that the
destruction of the semicircular canals does not destroy the hearing, but ren-
ders it painful and confused.

118 ZOOLOGY.

is an organ which is never wanting in any ear. A membranous
sac filled with a fluid, into which penetrate the nerves of
hearing, is the essential of the organ. In this fluid are
suspended some solid corpuscles which oscillate incessantly,
and which may be compared to the otolites of the internal
ear in fishes.

In most insects there is no vestige to be found of the organ
of hearing, and yet those animals do not seem insensible to
sound. Finally, in zoophytes, and in animals still lower, the
faculty of hearing itself appears to be wanting.

OF THE SENSE OF SIGHT.

§ 230. The sense of sight enables us to discover the pre-
sence of objects by their colours. It takes cognizance also of
their form, size, and relative position to us. The optic nerve,
the eyeball and its appendages, constitute the apparatus.

§ 231. Structure of the Eye. — The globe of the eye is a
hollow sphere, composed of membranes, and humours more
or less fluid. When the globe of the eye is dissected from
without inwards, it is found to be composed of the tunic,
called sclerotic, white and fibrous, and of great strength.
In front, and continuous with this, is the translucent cornea,
by which the rays of light pass into the interior of the
eye. If the cornea be opened, the aqueous humour escapes.
By removing the cornea, or a large portion of it, we
expose the iris, a coloured circular membrane, placed like
a partition between the anterior and posterior chambers of
the aqueous humours. The iris floats in this humour, is con-
tractile, and by its contractility the aperture in its centre,
called the pupil, and which in man is circular, varies
perpetually with the amount of light to which the eye is
exposed. This circular membrane is muscular, or at least
fibrous and contractile, and is abundantly supplied with
nerves.

Continuous with the iris, and extending backwards beneath
the sclerotic, is the dark vascular membrane, called choroid,
connected with the pigment of the eye ; and within it the
retina, or membrane in which the optic nerve terminates.

The humours which these membranes contain and circum-
scribe are in succession, proceeding from before backwards,
the aqueous humour, the lens, and the vitreous humour.

The optic nerve enters the eyeball towards the back part,

OF THE SENSE OF SIGHT. 119

passing through the sclerotic and choroid, and terminates in
the retina, which is generally viewed as an expansion of this
nerve. But other nerves
enter the eyeball, such as
the ciliary, coming partly
from the fifth pair and
partly from a ganglion, the
ophthalmic, with which the
fifth and third communi-
cate. From this ganglion,
though small, most of the
ciliary nerves proceed into
the interior of the eye to
supply the ciliary circle and
the iris. »' r v pc b

m The ciliary ligament or rig> 76>_Globe of the Eye

circle is a peculiar ring con- Dissected.*

necting the choroid, iris,

and sclerotic to each other. Its nature and functions have
not yet been determined, but it is well supplied with nerves
in animals of strong vision, as in the eagle and vulture.

[An extended series of inquiries into the structure of the
ciliary ligament, or body, induced me, many years ago, to believe
it to be of the same structure as the iris, and to assign to it the
functions of the adaptation of the eye to various distances. See
"Trans. Roy. Soc. of Bdin.," 1827.— R. K.]

The humours are colourless and transparent, and the same
remark applies to all the parts situated between the exterior
and the retina in the axis of vision, or measured by the size
of the pupil. The cornea is everywhere absolutely trans-
parent, and so is the conjunctiva which covers it.

In the iris, some of the fibres proceed like radii from
the free edge of the pupil towards the base : others surround,
as it were, the pupil, and act like a sphincter in contracting
the orifice. The aqueous humour, though quite transparent,

* c, the transparent cornea; s, sclerotic ; s', portion of the sclerotic turned
back to display portions of the membranes situated beneath it ; ch, the cho-
roid ; vt the retina ; n, the optic nerve ; ca, anterior chamber of the eye,
situated between the cornea and the iris, and communicating with the pos-
terior chamber by the opening in the iris called the pupil ; these chambers
contain the aqueous humour ; *, the iris ; p, the pupil, an opening in the iris
by which the rays of light pass into the deeper chambers of the eye ; cr, the
crystalline humour or lens ; pc, ciliary processes ; v, vitreous humour ;
b b, & portion of the conjunctiva.

120 ZOOLOGY.

contains a little albumen and salts, such as are met with in
all animal secretions. When suffered to escape by a puncture
or section of the cornea, it is speedily replaced. The ciliary
processes seen surrounding the capsule of the lens, and which
are appendages of the choroid membrane, are extremely vas-
cular, and may be the source of the secretion of this humour
and of the vitrine.

The crystalline humour or lens is a body of considerable
density, composed of concentric layers. It is enveloped in a
distinct capsule, and when removed in young animals may be
replaced by another. The lens is more convex posteriorly
than anteriorly in man.

The vitrine (vitreous humour) is a semi-solid body, enclosed
in a capsule, intersected by membranous partitions, in which
the fluid is contained. Its membrane is called the hyaloid.

In albinos, the pigment, an appendage of the choroid and
iris, is wanting.

Under a high microscope, the filaments of the optic nerve
seem to terminate in numerous cylindrical papillae, resembling
mosaic.

§ 232. Mechanism of Vision. — The sun and bodies in a
state of ignition are visible in themselves ; but other bodies
are visible to us only by the reflection of light in such a way
as to reach us.

Light moves with extreme rapidity ; it affects us only
when it reaches the retina ; opaque bodies reflect or absorb
it ; transparent bodies, as air, offer it a free passage.

Whatever obstructs the free passage of the light through
the conjunctiva, cornea, and humours of the eye, in its way
to the retina, obstructs or destroys vision ; hence the effects
of opacity of any of these structures : the cataract which
destroys vision is merely an opaque lens, which being removed
out of the axis of vision by the surgeon, restores the function
of the eye.

But these diaphanous parts of the eye serve other purposes
besides the negative one of permitting the free passage of the
rays of light into the interior of the eyeball; they change
the direction of the rays of light. The eye is but a kind of
camera obscura, the image of objects being as it were painted
on the retina; this image we see, and not the object itself.

To understand this part of the history of vision, it is only
necessary to refer briefly to some of the laws of optics.

Light travels in straight diverging lines. When they fall

OF THE SENSE OF SIGHT.

121

perpendicularly on the surface of a transparent body, they
traverse it without any change in their direction ; but falling
obliquely, they are always affected more or less in their direc-
tion. If they are passing from

a rarer into a denser medium, a

as from air into water, they are
refracted towards the perpen-
dicular ; the opposite happens
in passing from a denser into
a rarer medium ; they are then
refracted from the perpendi-
cular. A straight rod, for
example, plunged into water,
appears bent at the point of
immersion; and by placing a
coin in an empty basin (Fig.

77 a), so that it shall be invisible to the eye of the observer,
it will become visible by merely filling the basin with water
(e), for then the rays of light from the ewer which formerly
took the direction of <?, and did not reach the eye of the
observer, will now pass in the direction of d b, and so the
coin will be seen.

The form of the surface of the body on which the light
falls modifies greatly the further direction of the ray. Thus,
let us suppose that three rays start from the same point, a
(Pig. 78), traverse the air, and fall on the surface of a convex
lens. The ray a c striking the surface of the lens perpendi-
cularly will pass directly through it, experiencing no deviation ;

Fig. 77.

- 9

Fig. 78.

122 ZOOLOGY.

but the ray a d will be refracted at e, and proceed towards
the perpendicular ef\ the same will happen to the ray a g,
which being refracted at f, will become a i. By this refrac-
tion, rays of light passing through the lens meet at last in a
focus.

When the surface on which the rays strike is concave instead
of convex, the opposite effect takes place, as may be understood
by figure 79, in which b b represents the concave surface, a
the point whence the three rays start, a c the perpendicular
ray passing directly through, and the rays a d and a i will
assume the direction of cz/and a g.

The deviation which the rays of light thus experience is
proportionate to the convexity of the lens ; and the degree of
refraction is also in the ratio of the density of the body and
its combustibility.

§ 233. Apply these principles to vision. When the rays
of light fall on the cornea, some are reflected, and this gives
to the eyes their brilliancy and the power of seeing objects
reflected by them, as in a looking-glass. The rays passing
through the dense cornea are refracted Cowards the perpen-
dicular; they now meet the aqueous humour, which being less
refrangible than the cornea, restores them somewhat to their
primitive direction. Thus a greater number of rays pass
through the pupil than could have happened by any other
arrangement. The rays which strike the iris are absorbed or
reflected ; those falling on the pupil pass directly through it,
which of course admits more or less light, according as it is
more or less contracted. Under a strong light the pupil
diminishes; with a feeble light it dilates. The rays now

OF THE SENSE OF SIGHT. 123

meet the surface of the lens enclosed in its capsule, and are
thus brought to a focus, which falls on the retina, the rays
having in the mean time passed through the vitrine or
vitreous humour of the eye.

§ 234. It has been proved by many simple experiments
that the image is represented on the retina, and that it is
reversed ; the following figure (Fig. 80) explains how this
happens. The rays of light proceeding from the point a fall
on the retina at b ; those from c impinge the retina at d ;
thus the object is precisely reversed as painted on the retina.

Fig. 80.

§ 235. The pigment covering the posterior surface of the
iris, and all the inner surface of the choroid, is necessary for
perfect vision, as may be seen by examining the eyes of
albinos : it is only at night that their vision becomes
distinct.

§ 236. The globe of the eye is the most perfect of all
optical instruments ; for whilst it is in general achromatic,
it presents no aberration of sphericity,* and its range is con-
siderable. It possesses the power of adaptation to various
distances in its normal condition, although it has not been
satisfactorily explained on what structure this depends.
Within a short range it is obviously connected with the
presence of two eyes.

In some the eyes have not this power. Presbyopia de-
pends apparently on a deficiency of convergence of the rays of
light whilst passing through the humours of the eye ; hence
persons so affected do not see distinctly objects near at hand.

* By achromatism is meant the power of causing the light to deviate from
its course without developing or decomposing its rays into their primitive
colours.

The aberration of the sphericity consists in the reunion of the rays of light
which fall on different parts of a lens with foci distinctly different, whence

perform this function of correction.

124 ZOOLOGY.

An opposite defect is myopia, by which distant objects are
rendered indistinct, or not visible. The habitual use of a
strong lens has been thought equal to the production of this
disease. The myops has the sight improved with age, and
he may in time fall into the opposite condition, namely,
become presbyopic. By glasses, man endeavours to remedy
both defects.

§ 237. Insensibility to the rays of light is called gutta
serena. All parts of the retina are equally susceptible of
impressions, but it is the centre or in the axis of vision that
this sensibility is most acute.* The various points of the
retina may be exhausted of their sensibility by too strong a
light or by gazing intensely for a long time at one object.
The impression also which every object makes on the retina,
continues for a certain time after the object has been re-
moved ; thus it is that a body moving in a circle with great
rapidity resembles a ring or hoop, and that a wheel turning
with great rapidity resembles a disc.

§ 238. The section of the optic nerve produces immediate
blindness. But injuries of the thalami nervorum opticorum,
or of the corpora quadrigemina, also effect the same; and thus
it is evident that these bodies have the most intimate relation
with the optic nerves and the function of vision.

When the cerebral hemisphere of one side has been de-
stroyed in a living animal, it is the opposite eye which loses
its power; and this is partly explained by the anatomical
fact of the decussation of the optic nerves ; by this decussa-
tion, the right retina derives most of its fibres from, the left
side of the brain, and vice versa.

§ 239. Motor Organs of the Eyeball. — The apparatus
of vision is composed of the eyeball and its appendages ; of
these, let us first examine the muscles.

§ 240. The muscles enabling us to direct the eyeballs, and
consequently the axis of vision, upon any point, are six in
number. They are attached posteriorly (with one exception)
to the osseous orbit, around or near to the entrance of the
optic nerve, and by their other extremities to the sclerotic or
fibrous tunic of the eyeball (Fig. 81). The globe of the eye
rests on a cushion of a fatty cellular substance, and thus these
muscles can readily move it in all directions. The nerves,

* It is a remarkable fact that at the point where vision is most distinct,
the pulpy retina is wanting in man and in the apes of the Old World. The
appearance is called the foramen centrale retinae.— K. K.

OF THE SENSE OF SIGHT.

125

k •

Fig. 81.*

besides the optic, are the third, fourth, a branch of the fifth,
and the sixth pairs.

§ 241. Protecting
parts of the Eye. — These
are, 1, the osseous orbits,
requiring no special de-
scription here.

§ 242. 2. The eye-
brows, the eyelids, and
the tears. The eyebrows
require no description :
their form is sometimes
characteristic of different
races of men.

§ 243. The eyelids
are two in number, and
are horizontal. A third, when present, is vertical ; they are
called upper and lower, and differ in their anatomical structure.
Externally they are formed of a delicate integument, sup-
ported each by a fibre-cartilage (cartilago tarsi) ; internally
they are lined by the membrane called conjunctiva, which,
besides forming a layer of the eyelids, invests the front of
the eyeball. On the edges of the eyelids are observed cilia
or eyelashes, and a little behind these the Meibomian glands
are seen; these secrete a peculiar matter, preventing the
adhesion of the eyelids during sleep. Further, in each eyelid
the orbicularis muscle, or sphincter, gives a layer, and in the
upper eyelid we find the termination of the muscle called
levator palpebrse superioris, which raises the eyelid from off
the surface of the eye.

The uses of the eyelids are obvious. The sub-mucous
character of the conjunctiva assists in enabling the eyelids and
eyeball to play freely on each other ; but this is not sufficient,
and accordingly, to secure to the surface of the eye the requi-
site degree of moisture, the tears have been provided.

§ 244. The lachrymal apparatus is composed of a glan-
dular body, placed within the orbit, but exterior to the eyeball.
From this so called lachrymal gland, a few ducts proceed
and penetrate through the conjunctiva towards the outer

* Vertical section of the orbit. — a, the cornea ; b, the sclerotic ; c, the
optic nerve ; d, inferior rectus muscle of the eye ; e, rectus superior ; fy rec-
tus externus : a portion has been removed to show the optic nerve ; g, ex-
tremity of the small oblique muscle ; h, the great oblique or trochleator ;
i, levator of the upper eyelid ; Tc, lachrymal gland.

126 ZOOLOGY.

angle of the eye ; by these the tears are conveyed to the
surface of the eyeball. Here they are spread over the surface
by the movements of the eyeball and eyelids, until they
collect towards the inner angle of the eye, where will be
found the openings of two small ducts (puncta lachrymalia)
ready to convey away the superfluous tears. The fluid
entering these two short ducts is conveyed by them into the
lachrymal sac, which again communicates with the inferior

Fig. 82.*

meatus of either nostril by the nasal duct. When this is
obstructed, the tears flow over the lower eyelid, constituting
the disease called fistula lachrymalis.

Towards the inner angle of the eye is a small body, called
the canmcula lachrymalis ; also a fold of the conjunctiva,
which is very small in man, being merely the vestige of a
structure which, in some other animals, as in birds, is carried
to its highest development.

[This fold is in fact the rudiment of the third or vertical eye-
lid in birds.— E. K.]

§ 245. The structure of this apparatus is pretty nearly
the same in all mammals, birds, reptiles, and fishes. The
eye in certain mollusca also resembles the eye of animals much
higher in the range ; but in most of this class the structure
is very different, and as we descend to insects, Crustacea,

* h, i, punctum lachrymale. The two canals, k and I, open into the
lachrymal sac n, which passes off into the lachrymal duct ; Ig, lachrymal
gland ; p, pupil ; ir, iris ; c, cornea ; cl, caruncula lachrymalis ; up, upper,
and un, under eyelid.

OF THE MOVEMENTS. ' 127

arachnides, &c., the difference in structure becomes more and
more striking. These peculiarities will be adverted to here-
after.

OF THE MOVEMENTS.

Muscular Contraction.

§ 246. By sensation, man and animals perceive the ex-
ternal world ; by motion, they react upon it. This latter series
of functions is dependent on the property of contractility.

In some very simply organized animals, every part of the
body seems susceptible of contracting and elongating itself,
as in the hydra (Fig. 4) ; but as we ascend in the scale of
animals we find that the property belongs exclusively to the
muscular fibre. Collected in masses these form the muscles,
which again constitute the flesh of animals. Their colour,
which varies from a deep red to whitish, depends on the pre-
sence of the blood, and is not inherent in their structure.

§ 247. Structure of the Muscles. — The muscles are com-
posed of fasciculi, or bundles of fibres united by cellular tissue,
and these again of bundles of fibres more and more delicate,
until an elementary fibre, or what may be considered so, is
reached, and this can only be seen by means of the most
powerful microscope. It seems as if it were composed of a
series of discs. After death the muscular fibre is soft, and
easily torn ; during life it is firm and elastic. It is composed
essentially of fibrin, to which are united albumen, osmazome,
and some salts.

§ 248. By means of certain stimulants, such as the will,
muscles contract ; that is, they swell, shorten themselves, and
become extremely hard; the phenomena may readily be ob-
served by bending the fore-arm upon the arm.

The mechanism by which this is effected has not yet been
discovered. One thing alone is certain, that the two extre-
mities of the fibre or muscle approach each other, and thus,
of necessity, act on whatever they may be attached to that is
moveable, displacing one or both, and of course the body
itself. Hence these organs have been called the active organs
of motion, in contradistinction to the bones, which are

§ 249. The muscles are attached to the bones by fibres of
great strength, insensible, and of a dead-white colour; they
are called tendinous or tendons ; when membraniform in their
arrangement they are called aponeuroses.

128 ZOOLOGY.

[The true aponeuroses envelope the muscles of the limbs, and
form, as it were, a system apart from the tendons. — R. K.]

§ 250. Influence of the Nervous System on Muscular
Contraction. — The muscles are the only parts of animals
which possess the faculty of contracting ; but this property is
displayed only through the influence of the nervous system.

§ 251. Influence of the Nerves. — Each muscular fasci-
culus receives several nervous filaments. These proceed
parallel with the fibres enclosed in a neurilemma : they also
pass transversely across the muscular fibres and form loops,
but how they terminate is not known. They seem to form a
continuous circle.

By cutting the nerve across which supplies a muscle in a
living animal, the muscle becomes paralysed. By compressing
the brain of a living animal, all power of motion is lost.

§ 252. The nature of this influence of the nerves over the
muscles has been much investigated ; and the inquiry led
Galvani and Volta to some brilliant discoveries. They proved
that electric currents, however produced, act on muscles in a
similar way to the will, producing contractions in them even
after death ; and so closely did the phenomena resemble each
other, that it was at first thought that electricity, produced in
the brain, arid flowing thence into the muscles, was the effi-
cient cause of muscular contraction — a hypothesis incompatible
with certain facts recently observed. The nervous system is,
no doubt, the determining cause of muscular contraction.

§ 253. Muscles present very important differences amongst
themselves : some obey the will ; others, in addition to this,
also act independently of it ; whilst there are others over
whose acts the will has no power. The muscles of the limbs
may be cited as instances of the first class ; those of respiration
belong to the second ; the heart and stomach to the third.

The muscles of voluntary motion, as they are called, differ
generally from the involuntary, in being marked with trans-
verse striae ; but the fibres of the heart have these striae,
although it is in no respect a voluntary muscle.

§ 254. The muscles obeying the will all derive their
nerves from the cerebro-spinal axis.

§ 255. Influence of the Encephalon. — A transverse sec-
tion of the spinal marrow in a living animal paralyses the
action of all the muscles supplied by nerves which leave the
spinal marrow below the section ; those above the section
remain uninfluenced. The destruction of the brain paralyses

APPABATUS OF MOTION IN GENERAL. 129

all the muscles. Injury done to the corpus striatum renders
the muscular movements confused and uncertain ; the power
of retiring is lost, the movements being always in advance :
an injury done to the cerebellum (in birds) seems, on the
contrary, to disable the animal from advancing ; its move-
ments are constantly backwards.

By dividing vertically in a living animal one hemisphere
of the cerebellum, or one side of the pons, the animal moves
incessantly round and round towards the injured side. The
vital point of the encephalon seems to be close to the origin
of the pneumogastric nerves. The cerebellum and the ad-
joining parts of the brain seem to regulate the movements of
locomotion.

The movements which, though obeying the will, yet take
place independently of its influence, seem to be derived, then,
from the influence of the spinal marrow. The respiratory
movements, for example, go on after the brain has lost its in-
fluence over the respiratory muscles.

§ 256. Influence of the Ganglionic System. — The mus-
cular fibres, which are completely independent of the will,
receive their nervous influence from this system.

§ 257. Thus it would seem that, whilst volition proceeds
from the brain, the regulation of the movements proceeds
from the cerebellum ; whilst, in respect of those muscular
actions which are independent of the brain, the principle of
action seems to reside in the spinal marrow and ganglionary
system.

§ 258. Duration and Force of the Muscular Con-
tractions.— The contraction of the muscular fibres is a phe-
nomenon essentially intermittent; they relax and contract
alternately. Even the heart does this ; but the voluntary
muscles require a much longer interval of repose ; a lassitude
comes on at last, rendering all further action impossible.

Muscular fatigue varies much in different individuals ; so
also does the strength of contraction displayed. In passion
and in a maniacal state it is prodigious. The development
of the muscular system is best seen in the athlete.

Of the Apparatus of Motion in General.

§ 259. The function we have now to consider is chiefly
mechanical; it respects the various movements of animal
bodies.

K

130 ZOOLOGY.

In the lowest animals the muscles are all connected with,
and dependencies of, the integument, which is soft and
flexible, and by acting on this, they move the body in whole
or in part ; but in animals of a more perfect structure, the
motor apparatus becomes more and more complex, and is
formed not only of muscles, but of a skeleton, itself com-
posed of solid parts calculated to augment the precision, the
extent, and the force of the movements, to protect the viscera
against external violence, and to determine the general form
of the body.

§ 260. This framework or skeleton, to which the muscles
are chiefly attached, is in man, and all animals called verte-
brate, situated internally, and is covered by the soft parts.

In some fishes (as in the skate) the skeleton is formed of a
white, opaline, compact, homogeneous substance, at once very
resisting and elastic. It is called cartilage. In all animals,
when very young, the skeleton is at first cartilaginous ; but
this condition, which is permanent in certain fishes, is only
transitory in the greater number of animals, and the carti-
laginous pieces soon become charged with calcareous salts, by
which they become firm, hard, comparatively brittle : in this
state they are called bones.

§ 261. Of the Bones. — To prove the presence of cartilage
as the basis of all bones, all that is required is to immerse a
bone in dilute muriatic acid, which, dissolving the calcareous
part, leaves a cartilage of the precise form and dimensions of
the bone itself. According to Berzelius, the bones of the
human skeleton are composed of cartilage, 32* 17; vessels, 11*3 ;
phosphate of lime, with a little of the fluorate of calcium,
53*04; carbonate of lime, 11*30; phosphate of magnesia,
1*16 ; soda, with a little of the chlorine of sodium, 1*20 — in
100*00 parts. The same chemist found the bones of the ox
to be similarly composed, but with much less carbonate of
lime. Thus bones by boiling afford much gelatine.

The ossification of the skeleton commences with various
osseous points in the cartilages; these are called nuclei or
germs. In youth they are numerous, but they gradually
coalesce; thus the femur, in a young person composed of
five distinct portions, is at last formed of one. In the lower
vertebrate animals many of those remain distinct which in
the higher coalesce or become fused.

The surface of bone is covered with a cellulo-fibrous and
vascular membrane, called periosteum. The bones themselves

APPARATUS OF MOTION IN GENEBAL. 131

are composed of a compact tissue externally, and a cellular
and reticulated or cancellous internally.

In the interior of the long bones are found cavities con-
taining marrow. The tissue itself, when examined under the
microscope, seems composed of tubes or cellules, surrounded
with concentric lamellae, between which may be seen opaque
ovoid corpuscles.

§ 262. The bones vary much in form, and anatomists
have divided them into long, short, and broad. Their sur-
faces present elevations (processes) and depressions, some of
which are for the attachment of muscles.

§ 263. Articulation of the Bones. — By articulation is
meant the union of two or more bones ; they are divided into
the immovable or fixed, and the moveable. The fixed may be
effected by juxtaposition, suture, and implantation; of the
first, certain bones of the face offer an example ; the bones of
the cranium unite chiefly by suture, and the teeth are fixed
into the alveoli by implantation ; this mode of articulation is
also called gomphosis.

§ 264. In the moveable articulations, the bones are held
in their place by ligaments maintaining them in juxtaposition.
This bond of union is sometimes a fibro-cartilage, which
permits the bones to move simply by reason of its elasticity ;
in other joints, the bones slide over each other, and are held
in their place by ligaments attached to both bones, and per-
mitting of motion only in certain directions ; this mode of
articulation is called articulation Ijy contiguity, and it
always exists where extensive motions take place. To meet
the friction caused by this, the extremities of the bones are
further provided with a cartilage of incrustation, and a syno-
vial membrane representing a serous membrane in minia-
ture, and is constantly bedewed with an unctuous fluid, called
synovia, serving the purpose of a joint-oil. By means of this
membrane the air is effectually excluded from the joints, so
that the relative position of the bones to each other is further
secured by the pressure of the external air on the exterior of
the limb.

§ 265. Action of the Muscles on the Bones. — All the
muscles destined to perform extensive movements are attached
to the bones by their two extremities, so that by contracting
they displace the more moveable bone in the direction of that
which is less moveable or fixed. Thus, generally speaking,
the muscles intended to move the fingers proceed from thet
E 2

132 ZOOLOGY.

fore-arms; those moving the fore-arms are attached to the
arms or shoulders ; and those acting on the arms have their
fixed points in the trunk. But they may of course move the
parts to which they are attached by either extremity, or both.
To a certain extent also, the direction of the movement deter-
mines the position of the muscles. Thus, the flexors of the
fingers are situated on the front of the arm ; the extensors on
the back of the limb. When different muscles act in producing
the same movement they are called congenerous; antagonistic
if they produce opposite movements. Finally, they are named,
from their uses, flexors, extensors, abductors, &c.

§ 266. The strength of a muscle depends no doubt,
cceteris paribus, on its size ; but the effect depends also, in a
great measure, on its mode of attachment to the bone.

Thus, all things being equal, the movement of a muscle
will be so much the more extensive the less obliquely it is
attached to a bone.

In fact, if the muscle, m (Fig. 83), whose force we shall
consider as equal to 10, be fixed perpendicularly to the bone
I, whose extremity a is moveable on the point of support r, it
will have to overcome only the weight of the bone, and will
carry it from the position a b in the direction of the line a c,
thus making it traverse, to the point to which it is inserted,
a space which we shall represent by 10. But if the muscle
acts obliquely on the bone, in the direction of the line n b, it
will then have a tendency to carry it in the direction of b n,
and consequently to cause it to approach the articular surface

r, on which it rests as a point
of support. But this being
an inflexible body, this dis-
placement cannot take place ;
r the bone can only turn on
the point r as on a pivot, and
the contraction of the muscle
n, without losing any of the
energy assigned to it, can
d b l only carry the bone in the

Fig. 83. direction of a d. Three-

fourths of its strength will

be lost, and it will only be equal to effect a displacement for
which one-fourth of the strength expended would have
sufficed had its attachment been perpendicular to the bone as
the muscle m.

APPAEATUS OP MOTION IN GENEEAL. 133

Now in animal bodies, muscles are generally inserted very
obliquely, and thus very unfavourably in respect of their in-
tensity of contraction. The enlargement of the extremities
of the bones, as compared with the
shafts, serves to counterbalance
this obliquity in a certain degree, m
giving to the joints at the same
time more security. The tendons
(i) of the muscles (m) situated <
above the articulations, are in-
serted generally immediately be-
neath the enlarged extremity of ris- 84«
the bone, and thus reach the
moveable bone (o) in a direction more approaching the per-
pendicular, as may readily be understood by comparing Figure
85 with 84.

§ 267. The distance which separates the point of attach-
ment of the muscle from the point of support on which the
bone moves, and of the opposite extremity of the lever which
this organ represents, influences also in the most powerful
manner the effects produced by its contraction.

The bones represent levers, which move on a fixed point,
called the point of support. The force which puts the lever
in action is the power ', and that which opposes its displace-
ment is the resistance. Finally, the name of arm of
the lever of the power, and arm of the lever of the resist-
ance, is given to the distance separating the point of
support from that to which is applied one or other of these
forces.

Now the length of these arms of the lever has a powerful
influence over the force required to produce an equilibrium
to a given resistance. Observe the mechanism of the balance
called steelyard (Fig. 86). The beam is divided into two
unequal parts by the point of sup-
port a. At the extremity of one
of the branches (r) which is very
short, is placed the resistance,
that is, the object to be weighed ; r j
and on the other (p) slides any
weight which produces the equili- O
brium to a weight or resistance, ^S« 86«

always the more considerable that
it is further removed from the point of support, and that we

134 ZOOLOGY.

elongate, in consequence, the arm of the lever of the power,
the lever of resistance remaining always the same.

On the same principle it is that we can raise a so much
greater weight with the arm flexed instead of extended. It
is a question (see the figure) of shortening or lengthening the
respective arms of the lever to or from the point of support.
By mechanics we learn that, in order to establish a perfect
equilibrium (or to weigh the body as in the figure) in any
lever, it is necessary that the resistance and the power (the
weight and the weighed body) be reciprocally proportional to
the length of the arms of the lever; that is to say, that
multiplied by these arms of the lever respectively, they both
give the same product.

Thus, to produce an equilibrium to a resistance (r) equal
to 10, applied to the extremity of a lever (a b) of a length
equal to 20, it is necessary that the power (p), if it be applied
to the same point (b) and consequently equally distant from
the point of support a, be also equal to 10 ; but if it were
applied to the point c, to produce the same effect it must be
equal to 20 ; for the resistance equal to 10 being multiplied
by the length of its arm of the lever 20, will give as a product

p

i 1

P

1

fl

* rf I

c

•

r

o

r
f

i/*

Fig. 87.

200 ; and on the other hand, the arm of the lever of the
power (c d) being only equal to 10, thia must be multiplied
by a force equal to 20 to give the same product, 200. Finally,
by placing the former still nearer to the point of support at d,
a force must be given, but equal to 100, for its arm of
the lever will no longer be more than 2, and 2 X 100 = 200.
The disposition of the levers has as much influence over
the rapidity of the movements produced as over their force ;
and if by employing a power comparatively feeble we may
thus overcome a much stronger resistance, we may also, by
employing moving force having a certain quickness, obtain,

OF THE MOTOEY APPARATUS IN MAN. 135

by means of these instruments, a movement slower or more
rapid.

Thus let us suppose that the power (p) acts on the lever
(a r) so as to cause it to pass to the point of insertion c, a
space of 5 in a second, it will displace at the same time the
extremity (r) of the lever, and will cause it to arrive at b with
a quickness equal to 25,

for the distance passed v ^ r m j

through in equal times hy

this point will be five times

greater than that passed

through by the point d.

With a force equal in

rapidity to 5 we produce,

by applying it to the point

c, the same result as if we

applied to the point r a

force having a quickness

equal to 25. But all that

is gained in rapidity is lost in power or force ; for it is chiefly

by extending the arm of the lever of resistance to a length

disproportionate to that of the force that we obtain these

results.

Now, in the animal economy almost all the levers are so
disposed as to favour rapidity of motion at the expense of
force. Thus, in lowering the extended arm, if the rapidity
with which the muscles contract be such that their point of
insertion be displaced three inches in a second, the extremity of
the limb will pass from its original position with a rapidity
of nearly three feet per second.

Description of the Motory Apparatus in Man.

§ 268. The motory apparatus — as we have already
mentioned — is composed in man and all the vertebrata of the
skeleton, the muscles, and the articular apparatus.

The skeleton is divided into the head, trunk, and extremities.

§ 269. The Head. — The skeleton of the head is composed
of two portions — the cranium and face. The cranium lodg-
ing the brain, cerebellum, and pons, with their membranes,
the vessels proceeding to and from them, and the roots of the
cranial nerves, is composed of eight bones ; the frontal or
coronal (Fig. 89 f) : the two parietal, p ; the two temporal,

136 ZOOLOGY.

t ; the occipital, o, behind ; and the sphenoid, s ; and the
ethmoid below. These bones are generally broad and flat,
of a compact tissue externally
and internally, and are immo-
vably united by sutures dove-
tailed into each other. This
adds greatly to the strength
of the cranium and of the arch
it forms : the interlocking of
the sphenoid also with all the
other bones of the cranium con-
tributes greatly to its general
strength.

Fig. 89.* At the base of the skull

will be seen a great number of

apertures for the egress of the cranial nerves, and of the
bloodvessels entering or leaving the cranium. In the occipital
bone, close to its condyles, is the foramen magnum, by which
the medulla spinalis, or " myelon," passes towards the brain ;
the vertebral arteries, also intended to supply the brain, enter
by this large aperture. The cranium is articulated by means
of these two condyles of the occipital bone with the atlas or
first cervical vertebra, on which it rests nearly, but not quite,
in equipoise, so that during sleep the head naturally falls
towards the chest. The powerful muscles moving the head
are chiefly placed on the back of the neck.

At the sides of the cranium may be seen the mastoid pro-
cesses (Pig. 91 a), to which are attached the sterno-cleido-
mastoid muscles, seen so conspicuously on the front and sides
of the neck ; by means of these the head is turned from side
to side. Anterior to these may be seen the orifice leading to
the middle ear, and to which the external ear is attached
(§ 222, Pig. 73, .).

§ 270. The following bones compose the skeleton of the
face : the superior maxillary, 2 ; palatine, 2 ; malar, 2 ; lower
turbinated, 2 ; lachrymal, 2 ; vomer, 1 ; inferior maxillary, 1.
To these some add the intermaxillary, of which the vestiges
remain in man, 2 ; the sphenoidal turbinated, 2 ; finally, the

* ft frontal or coronal; p, parietal; tt temporal; o, occipital; s, the
sphenoid; n, the nasal; mst superior maxillary; j, jugal or cheekbone; mit
inferior maxillary or lower jawbone ; na, anterior opening of the nostrils ;
ta, auditory canal or foramen ; azt zygomatic arch ; ab, cd, lines forming the
facial angle.

OF THE MOTOEY APPARATUS IN MAN. 137

ethmoid and sphenoid contribute also to the formation of the
face.

These bones assist in forming certain osseous cavities con-
nected with the face, as the orbits (§ 241), the nasal fossae,
and the mouth.

The skeleton of the nose is completed by cartilages, which
being removed in the skeleton, makes the anterior openings of
the nasal fossae appear so large. These cavities are very
large and complex, communicating with the anterior and
posterior ethmoid cells ; the sphenoidal and superior maxillary
and frontal sinuses, and also with the middle ear. They
are separated from each other by an osseous and cartilaginous
partition or septum, and from the mouth by the osseous
palate. It is in the cavities of the nostrils that we find the
so-called turbinated bones, of which two are distinct bones,
the other four being but processes of the ethmoidal. The
importance of these bones, as regards the sense of smell, has
been already adverted to.

ttn mo c

Fig. 90. -Head of the Horse.*

It is into the superior maxillary bone (speaking with refe-
rence to man) that are implanted all the teeth of the upper
jaw.J In youth it is, like most other bones, formed of

* oc, t, f, occipital, temporal, and frontal bones ; n, nasal bone ; my
superior maxillary; im, intermaxillary; mi, inferior maxillary; o, orbit;
t, incisive teeth ; c, canine ; mo, molar.

t Principal muscles of the face and head: — o, orbicular muscles of the eye-
lids, intended to close the eyelids and protect the eyes; bb, orbicular muscle
of the lips, intended to close them and to contribute greatly to speech, the
expression of the passions, &c. ; j, muscles of the cheeks ; m, masseter
muscle, intended to close the jaws by raising the lower maxillary bone ;
t , temporal muscle having the same function : z, zygomatic arch ; c, articu-
lation of the lower jaw ; a, auditory meatus and mastoid process.

J Anatomists now generally admit that mail has intermaxillary bones as

138 ZOOLOGY.

several distinct germs, nuclei, or portions, which, ultimately
coalesce.

These intermaxillary bones which fuse so early in man,
remain distinct throughout life in many mammals and others,
and form a distinctive feature of the face. They are also
called premaxillary (i m Fig. 90).

In man the germs of the lower jawbone become fused at
an early age; in many mammals it is formed of two pieces,
united by cartilage at the symphysis of the chin. A brief
inspection of the lower jawbone shows its more remarkable
points : its articular surface, by which it rests on the glenoid
cavity of the temporal; the coronoid process projecting
upwards in front of the condyle, and to which is attached the
powerful temporal muscle ; the alveolar edge of the jaw, form-
ing its dentar portion ; the symphysis or union of the chin,
and the base and angle. The masticating muscles are very
powerful, especially in the carnivora ; and in some animals
the disposition of the muscles rendering the arm of the lever
of resistance equal to, or even shorter than that of the power,
adds to their strength.

The hyoid or lingual bones (Fig. 31), placed in front of the
neck, representatives of another apparatus, of which in man,
mammals, birds, and most reptiles, we have only the rudi-
ments, and which only attain their full development in fishes,
give attachment to the muscles of the tongue and to others.
They are not considered as part of the skeleton, properly so
called.

§ 271. The Trunk, or Torso. — The most important part
of the skeleton of the trunk is the vertebral column, composed
of the bones called vertebrae. It supports the head, which
may be considered as a continuation of it ; but anatomists
still speak of the vertebral column as a part distinct from the
head. In this view it is composed of 33 vertebrae, namely,

well as other mammals, which early become fused with the maxillary, so that
nearly all traces of their early existence are lost. The incisive teeth always
appear in these bones in the upper jaw, and whatever be their shape, so long
as they belong to these bones are called incisive. Thus the enormous tusks
of the elephant are called incisors, notwithstanding their shape and size,
simply for this reason, that they grow in the intermaxillary bones. For the
same reason we call the gnawing or cutting teeth of the beaver, porcupine,
hare, rabbit, incisive teeth, and not merely from their functions. Notwith-
standing, it is right to observe that the upper incisors of the rabbit grow
from a pulp, the extremity of which is lodged in a small osseous cavity of
the upper maxillary bones. They merely pass through the intermaxillary
bones, which furnish them no doubt with their chief support, mechanically. —
It. X.

OF THE MOTOBY APPAEATUS IN MAN.

139

7 cervical (c) ; 12 dorsal (d) ; 5 lumbar (I)-, 5 sacral (s); and
4 coccygeal (or). It presents several curves when viewed in
profile, but is straight when seen from before
backwards, or from behind forwards. At first
all the vertebrae are distinct, but with years
certain of them become fused into one or more :
the 5 sacral vertebras generally unite so as to
form one mass ; and the coccygeal bones are also
disposed to fuse into one bone in the adult.

The essential character of a vertebra (with
certain exceptions, however) is to be formed or
composed of a body and processes, and to have
a foramen, or short canal, behind the body, in
which the spinal marrow and its membranes are
lodged. But the coccygeal vertebrae in man are
quite rudimentary, and cannot be included in
this definition. At the sides of the column are
openings for the passage of the nerves ; they are
called the foramina intervertebralia, and are
generally formed by the union of two vertebrae.

The body or centrum of a vertebra is a disc Kff' 92-
(a), with parallel surfaces, each united (with cer-
tain exceptions) to the adjoining vertebra by a substance
called inter vertebral ; this is a fibro-cartilage of great strength,
flexibility, and elasticity, on which the strength
and mobility of the column greatl}r depends.

Four articular processes also greatly contri-
bute to its strength, and limit its movements in
certain directions. The spinous process (neural
spine) 6, as well as the transverse processes or
parapophyses c, give attachments to numerous
muscles, and the latter support the ribs.

The mobility of the column varies in different
regions, being most extensive in the neck and loins. The
erector muscles of the spine, those intended merely to raise
the body upright, and to counterbalance the weight of all the
viscera situated in front, are placed on the dorsal side of the
column, filling up the grooves called vertebral, and which may
be seen extending on either side the spinous processes, from
the head quite to the extremity of the sacral vertebras. They
seek attachments also in the ribs and transverse processes of
the vertebrae.

The spinous processes (neural spines) are long and powerful

Fig. 93.

Frontal Bone (11).

Parietal Bone (7).

Orbit.

Temporal
Bone (27,

Lower Jaw
(29, 32).

Cervical
Vertebra

Shoulder
Blade (51).

Humeru
(53).

Lumbar
Vertebrae

Ilium

Ulna (54)
Kadius (55>

Carpus (56)

Metacarpus

(57).

Phalanges
(57).

Femur (65) -

Tibia (66).
Fibula (67).

Patella
(66').

Tarsus (68).

.Metatarsus

(69).

* Phalanges
(69).

Fig. 94.— Human Skeleton.

OF THE MOTOEY APPARATUS IN MAN.

141

in many quadrupeds (Fig. 95). The muscles, on the other
hand, situated on the flexor side of tRe body, are generally
small, as being but little required.

The first cervical vertebra is called the Atlas, and is much
more moveable than the others ; it resembles a ring, and
turns on its own centrum, which is immoveably connected
with the second vertebra or dentata (axis). The movement of
the head forwards and backwards takes place at the articula-

Fig. 95.— Skeleton of the Camel.*

tion of the occipital bone and atlas ; rotation of the head is
performed by the atlas and head moving as one around the
processus dentatus of the axis or second vertebra. There exist
check ligaments to prevent this movement going too far.
§ 272. To the dorsal vertebrse are articulated the ribs,

* The dark line represents the outline {silhouette) of the living animal ;
vc, cervical vertebrse; vd, dorsal vertebras; vl, lumbar vertebrae; vs, sacrum
or sacral vertebras; vq, vertebrse of the tail, or caudal ; c, the ribs ; o, scapula;
h, humerus ; cu, ulna, or cubitus ; ca, carpus ; me, metacarpus ; ph, pha-
langes ; fe, femur ; rot rotula ; ti, tibia • ta, tarsus; mt, metatarsus.

142 ZOOLOGY.

24 in man, — i.e., 12 on each side. The head of the rib rests
on the vertebral colurhn, and the tubercle on the transverse
process generally ; the anterior extremity of the rib is united
to a cartilage, by means of which it is prolonged to the
sternum, directly in the first seven ribs, and indirectly in the
remaining five. Hence the division of the ribs into true and
false, or sternal and asternal (Fig. 96).

§ 273. Limbs. — The skeleton of the limbs may be divided
into a basilar portion, and a lever or extended and moveable
part. In the pectoral extremity the basilar portion or
shoulder 'consists of two bones, the scapula and the collar-
bone or clavicle. With the scapula, a large and flat bone, is
articulated the humerus or arm-bone. The articular cavity
(glenoid) has but little depth. On the inner side of this
glenoid cavity is a strong process, called coracoid, and on the
dorsal side of the bone a strong spine, running from near its
base, and terminating in a process called acromion; sur-
mounting the shoulder-joints and attached to this process is
the clavicle, a cylindrical and slender bone, comparatively ; its
other extremity is articulated with the manubrium of the
sternum (Figs. 94 and 96).

The more obvious use of the clavicle is to maintain the
shoulders apart, and hence the frequency of its fracture when
forced towards the sternum. These clavicles are strong in
birds of powerful flight, and weak in those differently circum-
stanced : contrast, for example, the eagle and the turkey. In
animals like the horse, ox, &c., they are wholly wanting; the
scapula, as the essential bone of the shoulder, never.

Numerous powerful muscles fix the shoulder-bones to the
trunk ; of these may be mentioned the trapezius, rhomboids,
and levator of the angle of the scapula; a muscle of great
power, even in man, but much more so in the larger
quadruped mammals, as the horse, ox, &c., connects the
scapula with the ribs, viz., the serratus magnus.

§ 274. The arm is divided into arm, fore-arm, and hand.
In the skeleton of the arm there is one bone, the humerus;
in that of the fore-arm two bones, the radius and ulna ; the
skeleton of the hand is subdivided into three segments, the
carpus, metacarpus, and fingers; in the carpus there are
eight bones ; in the metacarpus five ; and in each finger there
are three bones, with the exception of the thumb, in which
only two are reckoned.

The humerus has a ball-and-socket motion upon the

OF THE MOTORY APPARATUS IN MAN. 143

scapula, and is moved by several powerful muscles, of which
some proceed from the scapula (sub-scapular, supra-spinal,
infra-spinal, teretes) ; others from the trunk, as the pectoralis
major, latissimus dorsi. By its lower or distal extremity,
it articulates with the radius and ulna.

§ 275. The radius and ulna form the skeleton of the
fore-arm. Of these, the radius is the more moveable, and
upon its rotation on the extremity of the humerus depends

i Vertebral Column. Kibs.

.--Clavicle.

Intercostal!
Muscles. \

Fig. 96.— Thorax of Man.*

the movement of rotation and supination of the hand. There
is no rotation at the elbow-joint, both bones moving on the
humerus merely in flexion and extension ; but it is close to
this that the radius rotates on the ulna, and slides over the
smaller head of the humerus, which movement determines
the rotation of the hand in supination and pronation. The
lower end of the ulna is styliform, and has interposed between
* See explanation of this figure at page 77.

144 ZOOLOGY.

it and the carpal bones a fibre-cartilage of a triangular shape,
which attaching the radius at its extremity to the ulna,
permits the former to rotate around the lower end of the
latter, which remains fixed.

These two bones at their carpal extremities also move
readily in flexion and extension.

The process called olecranon belongs to the ulna or cubit ;
to it are attached the extensor muscles of the fore-arm.

§ 276. In the hand we have the carpus, metacarpus, and
fingers, or digital portion.

The carpus is composed of eight bones, four in each row j
they are scarcely moveable, and the strength of the arch they
form is considerable. In the first row we find the scaphoid,
semilunar, pyramidal, and pisiform; in the second row the
trapezium, trapezoides, magnum, and unciform. On the
flexor side of the hand they form with the anterior annular
ligament of the carpus, a canal, in which are lodged and
protected most of the flexor tendons, and one of the great
nerves (median) proceeding to the palm of the hand.

The metacarpus is composed of a single row of small long
bones, corresponding to the number of the fingers, all diffe-
rent and readily distinguishable from each other. Four of
these move but little ; the first, which supports the thumb,
and which some view as the proximal phalanx of that finger,
is very moveable, corresponding to the greater mobility of
the thumb as compared with the other fingers.

Finally, the fingers have each three bones, called proximal,
middle, and distal phalanges ; in the thumb there are only
two. The distal phalanx supports the nail, and is sometimes
called the nail-bone, or ungual phalanx.

§ 277. When we consider the arm as a series of broken
levers, we observe that the arm is longer than the fore-arm,
and this longer than the hand : or, in other words, that the
mobility of the structures and their flexibility and power of
adaptation increase as we approach the extremity, properly so
called.

§ 278. The structure of the inferior or pelvic extremities
has the strongest analogy to that of the superior limbs, and
the principal differences to be observed have a necessary
relation to their functions ; to make of them, in fact, instru-
ments of locomotion rather than of prehension. Hence their
solidity, at the expense of their mobility. They also have a
basilar portion, the haunch, the representative of the shoulder,

OF THE MOTOEY APPARATUS IN MAN. 145

and an articulated lever, formed of three principal parts —
the thigh, the leg, and the foot — corresponding to the arm,
the fore-arm, and the hand.

§ 279. The haunch or basilar portion of the abdominal or
pelvic extremity is composed of one bone on either side, the
os innominatum or haunch-bone. In the young this bone
is composed of three large portions, called pubic, iliac, and
ischiatic portions. These have been considered analogous to
the scapula, coracoid process, and clavicle. These bones, the
ossa innorninata, are articulated in the most solid manner with
the sacrum by strong articulations, and with each other at
the pubis ; these joints are immovable in their normal state :
with the sacrum and coccyx, the innominata form the osseous
girdle, called the pelvis, surrounding the lower part of the
trunk. To this basin or pelvis are consequently attached the
powerful erectors of the spine, the muscles which are to
move the lower extremities, and those which shut in the
abdominal and pelvic cavities.

§ 280. In the thigh there is but one bone, the femur
(Pig. 94). The head of this bone, by which it articulates
with the pelvis, forms, with the cotyloid cavity of the haunch -
bone, a perfect ball-and-socket joint, protected by a capsular
ligament, permitting of circular movements, or nearly so.
A short neck (cervix) connects the spherical head of the
femur to a powerful cylindrical shaft, which enlarges towards
its lower extremity, by which it articulates with the tibia.
This is by much the longest and strongest bone of the body.
Powerful muscles surround and move it in all directions,
excepting backwards or in extension.

§ 281. The skeleton of the leg is composed of two
bones, the tibia and fibula. The rotula or patella, attached
to the tibia by a powerful ligament, or rather tendon, is a
sesamoid bone, developed in a fibro- cartilage connected with
the system of the tendons. The tibia carries the whole
weight of the body, transmitted to it through the femur,
which it transmits to the astragalus. There is no rotation at
the knee-joint in general, nor at the ankle. The malleoli
formed by the lower ends of the tibia and fibula assist in
forming a case for the head of the astragalus.

§ 282. The foot, like the hand, is divided into three

regions : the tarsus, metatarsus, and toes. In the tarsus

there are seven bones, the astragalus, os calcis, scaphoid,

cuboid, and three cuneiform bones ; in the metatarsus there

L

146

ZOOLOGY.

are five bones, reckoned numerically, from the inner to the
outer side of the foot ; and in the region of the toes, there
are for the great toe, two phalanges, and for the others three;
besides these, as in the hand, there are two sesamoid bones,
constant and regular, developed in the tendon of the short
flexor below the ball of the great toe.

In man the great toe cannot be opposed to the others ; the
second toe is the longest in all well-formed human feet. The
tarsal and metatarsai bones form a strong arch towards the
inner and lower surface of the feet, protecting the vessels,
nerves, and tendons passing from the foot to the leg, and the
opposite. The short flexors of the toes are placed in the sole
of the foot; the tendo-Achilles, the strong tendon through
which the extensor muscles act on the foot in walking, is
attached to the tuberosity of the calcarieum. The size of the
peroneal muscles is a peculiarity in the human leg. The
same remark applies to the gastrocnemii muscles.

Of the Attitudes and of Locomotion,

§ 283. All mammals, birds, reptiles, and fishes have a
skeleton formed on the same plan as in man. It gives to
the body its general form, regulates its development and
movements.

§ 284. Station or Standing. — With the exception of
serpents, most animals rest on the soil by means of limbs or

extremities. They

r stand by means of

the action of the ex-
tensor muscles : and
thus standing for
a long time erect
becomes more fa-
tiguing than walk-
ing, for in this the
— . flexorsand extensors
are used alternately.
§ 285. But the
body must also be
in equilibria, or
balanced on its base of sustentation ; and the point around
which all its movements are performed is called the centre of
gravity. Now, to support the centre of gravity, it is neces-

Fig. 97.

OF THE ATTITUDES AND OF LOCOMOTION.

147

sary that the base of sustentation he situated vertically below
the centre of gravity. The wider, then, the base of sustenta-
tion is, the more secure the position : thus we stand safer
on two feet than one ; on the sole of the foot than on the toes
or heel, &c. ; for in proportion to the extent of the base of
sustentation, so may the centre of gravity be displaced with-
out risk of its falling beyond that base. The law holds good
in all heavy bodies ; thus, the table (a) represented in Fig. 97

c*.' 3' **

Fig. 98.

must fall, because the vertical (c), let fall from its centre
of gravity (e), would fall beyond the limits of its base of
sustentation (a), or in other words, the foot of the table. or the
space occupied by it; whereas the table (b) would not fall, for
the base of sustentation is sufficiently large to allow the
vertical from the centre of gravity to fall within its limits.

On these simple principles may readily be explained the
safety of the position of the quadruped as he stands on four
limbs ; how it becomes less safe on three, still less on two ;
and how readily the bird secures itself on one leg in conse-
quence of the breadth of the foot which is the base of susten-
tation. Man stands readily on one limb, and with little
fatigue, especially if he use the other to secure his equilibrium ;
for the centre of gravity being in him towards the middle of

* To show the varying centre of gravity in man.
L 2

148

ZOOLOGY.

the pelvis, all that is required is to recline the body a little
to one side, so that the centre of gravity may fall on the sole
of the foot which receives the weight.*

Most quadrupeds can neither
stand on one foot nor even on
the two hinder limbs; it is im-
possible for them to maintain,
excepting for a few seconds,
such a position; the base of
sustentation is too narrow;
their centre of gravity is to-
wards the chest, and the
muscles are not strong enough
to maintain the attitude. But
in man this position is easy,
natural, and belongs to him by
the character of his organiza-
tion.

§ 286. In the vertical posi-
tion it is chiefly the extensor
muscles which are called into
play; the limbs forming broken
levers become fixed ; the knee

Fig. lOO.t

Fig. 101.

and ankle become immovable.

§ 287. Sitting is less fa-
tiguing than standing; but the horizontal position is that
alone which gives absolute rest to the body.

§ 288. Walking. — When we walk, one of our feet is
carried forwards, whilst the other is extepded on the limb ;
and as this forcibly extended foot rests or presses against a
resisting soil, its elongation displaces the pelvis, and thus

* Standing on one foot, using but little muscular effort, requires the
centre of gravity to be thrown forwards so as to fall towards the fore part of
the base of sustentation ; the knee tends then to bend backward, but is fixed
and rendered immovable by the- posterior ligament of Winslpw. Thus the
knee becomes fixed by a mechanical artifice requiring but little muscular
effort. But if we shift the centre of gravity so as to make it pass directly
through the joint, a strong muscular effort is required to fix the knee-joint ;
the extensor muscles are called into play in order to fix the patella, and the
position cannot in consequence be long maintained. — E. K.

t Fig. 100, hind foot of the horse. Fig. 101 , foot of the stag ; t, the tibia,
ta, first row of the bones of the tarsus ; ta, second row ; c, metatarsus or
cawowbone ; s, styloid bone formed by the skeleton of a rudimentary finger ; —
there are two such ; p, proximal phalanx, called the great pastern ; pi,
middle phalanx (little pastern) ; pt, distal phalanx, or coffin-bone of veteri-
narians.

OF THE ATTITUDES AND OF LOCOMOTION.

149

projects the whole body forwards ; at the
same instant, the pelvis turns a little on
the femur of the opposite side, and the leg
which at first remained behind, bends, is
carried forward, and in its turn is placed
on the soil, to carry forward the whole
body by the extension of the foot. By the
aid of these alternate movements of flexion
and extension, each limb carries in its turn
the weight of the body, and at each step
the centre of gravity is pushed forwards.
For an instant the body is carried alter-
nately on one foot, and the centre of
gravity is carried flexuously from side to
side at each step, and this in proportion
to the width of the pelvis.

§ 289. As the functions of every appa-
ratus are always in relation with the
structures, so the limbs of various animals
show great variety in their disposition.
Thus, amongst mammals, some are des-
tined to move in water or on land — that
is, to swim or walk, as suits them, or to
swim only ; others have the limbs formed
for speed ; others, as bats, fly like birds ;
some use their fore limbs only as instru-
ments of prehension or touch ; and yet the
limbs in all these animals are formed pre-
cisely on one plan. In the swimming
limbs of the seal, the wing of the bat, the
fore limbs of the squirrel or mole, we find

* Skeleton of the right fore leg of the Asiatic
Elephant. In the construction of the legs of the
elephant, Nature seems to have done her utmost to
combine enormous strength with a remarkable de-
gree of agility. The ulna, which in other animals
falls off as it approaches the wrist, and is articulated
only indirectly with the carpal bones, in the ele-
phant, on the contrary, enlarges to a size even
greater than the radius, and is articulated directly
with the carpus. The other exception to the almost
universal law of the falling off of the ulna, I dis-
covered in the dugong, and pointed it out as one of Fig. 102."*
the characters separating the dugong from the

Cetacea, in which I had placed it. Long afterwards, the illustrious De
Blainville accepted of my arrangement as the only correct one, and restored
the dugong to the elephant, to which it more nearly belongs.

150 ZOOLOGY.

the same number and arrangement of the bones (Fig. 94) as
in the human arm.

§ 290. In mammals organized for speed, the limbs are
slender and the feet small ; we see this in the horse, stag, and
camel, in which the toes are but little divided (Fig. 95), and
the number of the toes is reduced to its minimum ; in the
horse, for example, there is but one toe or finger perfect, two
others being imperfect and concealed (Fig. 101) ; in others
there are two, either alone or with vestiges of one or two
others, and these always short and not very moveable.

In those also remarkable for speed of foot, the limbs are
long ; and this is a necessary result of the mechanical prin-
ciples already explained.

Fig. 103.— Skeleton of the Kangaroo.

§ 291. Leaping. — In walking, the weight of the body is
sustained by a portion of the locomotory apparatus, whilst its
centre of gravity is being pushed forward by the other part
of the apparatus, so that man never ceases to touch the soil.
In leaping it is otherwise ; the body is thrown into the air,
and becomes, as it were, a projectile. To effect this, the
articulations are strongly flexed, so that, by a strong and
forcible and sudden extension, the body may be forced up-
wards from the resisting soil. Between the body and the
soil there is, in fact, an apparatus representing an elastic
spring — the joints; on these extending violently and sud-
denly one of two things must happen, if the spring be suffi-
ciently strong — either the soil must yield or the body, and
this being generally the only moveable, gives way and becomes

OF THE ATTITUDES AND OF LOCOMOTION. 151

the projectile. Were the soil to yield under the feet, it is
obvious that no leap could take place. With quadrupeds, it
is principally the hinder extremities which act as the spring
or force ; and hence, in animals of great speed, as the ante-
lope, horse, &c., these limbs are long, and flexed, and slender.
In some, as in the jerboa and kangaroo, the anterior limbs
are but little, if at all, used in progression.

§ 292. Swimming or Flying. — These movements are
analogous to leaping, the only difference being in fact in the
medium in which they take place. The points to be con-
sidered are, first, the medium, which in the case of flying is
the air, and this, by reason of its rarity and the facility of its
displacement, requires being struck with much greater force
and rapidity than if it were water, or the still more resisting
soil. Hence the great force required by birds in the muscular
apparatus by which flight is effected. Second, diminution
of the surface of the motory organs during the advance
of the body, so as to offer less resistance to the passage of the
body through the air. Now, these two conditions we shall

Fig. 104.*

find uniformly take place in animals which fly or swim
naturally ; the expanded foot of the seal . diminishes during
the moment of advance, and the wing of the bird approaches
the sides ; the flanges attached to the archimedean screw are
but poor imitations of the tail-fin of the whale.

§ 293. The palmated feet of the otter and seal, of the
swan and duck, represent and explain the mechanism by which
nature provides for the wants of an animal requiring at

* Skeleton of the foetus of the Greenland whale. The specimen was re-
moved for me from the uterus of its mother, a full-sized Mysticetus or
Greenland whale, by Mr. Robert Auld, one of my students. The skeleton
was long in the museum in Old Surgeons' Hall, and is now in that of the
University of Edinburgh.

152

ZOOLOGY.

times to swim at others to walk on the soil ; the otter also
furnishes a good example of this mechanism. But nature does
not for all this depart from her great plan in the construction

Fig. 105.— Skeleton of the Seal.*

of animals ; the skeleton of the hand and foot of the seal
resembles ours (Fig. 105), admitting that in some, as in the
whale, the number of phalanges appears to exceed that of
mammals generally, and that the fingers themselves seem to
be replaced by a number of osseous pieces, reunited under
a common integument, as is seen in the fins of fishes.

Fig. 106.— The Flying Fish (the Dactylopterus) .

§ 294. The structure of the organs which enable an
animal to fly, has much analogy with the fins generally ;
thus there are fishes (Fig. 106) which use indifferently for
progression in air or water their pectoral fins.

* The bones are lettered as in Fig. 95.

OF THE ATTITUDES AND OF LOCOMOTION.

153

Some squirrels, and the Galeopitheci, have a wide ex-
pansion of the common integuments extending on either
side, from the neck to the tail
and hinder extremities; and by
this they can support themselves
in the air for a short time; it
answers, in fact, the purpose of
a parachute.

In the vertebrata, the wings
are always formed by the pectoral
extremities, without requiring on
the part of the limb any very ex-
traordinary metamorphosis. The
figure (108) representing the
skeleton of the bat explains this
sufficiently; the phalanges of the
fingers are much extended, and
with them the integuments.

The wings of birds, which at
first sight seem to differ essentially
from the arm of man, the foot of
the horse, and the swimming
paw of the whale, in point of
fact do not differ as regards
the basis of the instrument, the skeleton. To the bones
representing the fore-arm and hand, analogous to those
of man, are attached the powerful feathers of the wing; the
hand is small, and the digital portion merely rudimentary ;
but the basilar portion of the limb is always powerful, and
perfectly adapted for flight.

The wings of insects are constructed pretty nearly on the
same plan as those of birds, but the tegumentary part is
supported on horny stalks, instead of osseous, as in the
vertebrata.

§ 295. Organs of Prehension. — By slight modifications
in the form of the bones, and in the disposition of the articu-
lations, the limbs become instruments of prehension, instead
of mere locomotion and support. To be satisfied of this, it is
only necessary to compare the pectoral and abdominal
extremities in man, section by section, and bone by bone ;
the rotation of the radius, and the con sequent movements of
pronation and supination, together with an opposing thumb,
constitute in reality the chief differences between the arms

Fig. 107.— Galeopithecus.
Flying Lemur.

The

154 ZOOLOGY.

and limbs. Many apes of the New Continent (America)

Sf*

Fig. 108.— Skeleton of the Bat.*

opossums, &c., have prehensile tails ; amongst reptiles, the
chameleon offers the same peculiarity.

OF THE VOICE.

§ 296. In certain of the lower animals there exists no
trace of this faculty; in insects, the sound produced by the
friction of their wings, or of some other tegumentary parts,
is a necessary result of their movements, — as of flight, for
example, — and can scarcely be viewed as a phenomenon of
expression. But in the higher animals the voice acquires
another importance : it is under the direction of the will ; it
is more varied, and depends on a totally "different cause ; for
in all these, it is caused by the passage of the air through a
determinate point of the respiratory canal, disposed in such a
way as to cause the air to vibrate.

§ 297. The larynx (Fig. 31), surmounting the trachea
and communicating directly with the pharynx, and by its
means with the nostrils and mouth, is the organ of the voice
in man and in mammals. It may be felt on the surface of the

* The bones have the same letters as in Figure 95 : cl, the clavicle; op,
the thumb.

THE LARYNX.

155

neck, a little below the hyoid bones. Experiments on
living animals, and observations made on those who have
undergone the operation of tracheotomy, that is, of having an
aperture made into the windpipe between the lungs and the
larynx, prove that the voice is formed in that organ.

§ 298. The Larynx. — The larynx is a short and wide
tube, suspended to the lingual bones, and continuous with
the trachea or windpipe inferiorly (A, Fig. 111). Its walls are
formed of cartilages called thyroid (t), cricoid (c), arytsenoid
(a r, Fig. 112). The salient angle of the thyroid felt
on the surface of the neck in man, still retains the vulgar

Fig. 109.— Skeleton of the Vulture.*

name of pomum Adami (a) ; a mucous membrane, con-
tinuous with that covering the tongue, mouth, nostrils, and
pharynx, lines its interior, and, extending downwards into
the trachea, becomes the mucous membrane of the lungs

* The different bones are ipdicated by the same letters as in the preceding
Figures.

156

ZOOLOGY.

themselves. In the interior of the organ, this mucous
membrane forms four folds, two superior!}7', called the false
vocal cords, and two inferiorly, called the true vocal cords.

Fig. 110. — White-throated Sapajou, or Sajou, Cebus hypoleucos.

It is here, upon the edge of these folds, by the air impinging
and causing them to vibrate, that the voice is formed.
(Figs. 112 and 113.)

These folds are in consequence called the vocal cords or
ligaments of the glottis, the space between the true ligaments
being called the glottis or rima glottidis } the true vocal cords
are formed interiorly of folds of mucous membrane, and ex-
teriorly of elastic ligaments, which stretch from the interior
of the salient angle of the thyroid cartilage to the arytsenoid
cartilages. By the muscular apparatus attached to the larynx,
not only the entire larynx can be moved up and down in the
neck, but these ligaments or true vocal cords can be made
tense or relaxed, so as to diminish, enlarge, or all but close
the aperture called rima glottidis, through which the air must
pass and repass in its way to and from the lungs. Between

MECHANISM: OF THE VOICE.

157

the true and false ligaments of the glottis or vocal cords, on
either side there is a cavity, called the ventricle of the larynx.
Lastly, superiorly, the upper aperture of the larynx (which
must not be confounded with the rima glottidis) is protected
by a fibre-cartilage, of a triangular shape, called epiglottis,
by means of which, during deglutition, the larynx is still

further protected from the accidental passage of food or drink
into the air-tubes, the effect of which accident, unless in-
stantly relieved, is suffocation.

§ 299. Mechanism of the Voice. — In the ordinary state
the air passes and repasses the larynx, and no sound is heard ;
but when the muscles of the larynx contract so as to modify
the vocal cords as to tension, and to affect the diameter of the
rima glottidis, sounds are immediately produced. The cele-
brated Galen divided in a living animal the nerves proceeding
to the larynx, and first showed the phenomenon to depend on
muscular action influenced by the nerves. By cutting the
true vocal cords the voice is destroyed altogether.

* Fig. 111. The male larynx viewed in profile : h, hyoid bone ; I, body of
the hyoid, giving attachment to the base of the tongue ; t, thyroid cartilage ;
a, salient angle of the thyroid cartilage, which may be felt on the surface of
the neck (pomum Adami) ; a membraniform ligament unites the thyroid
cartilage to the hyoid bones ; c, cricoid cartilage ; tr, trachea or windpipe ;
o, posterior wail of the larynx in relation with the gullet.

Fig. 112. Vertical section of the larynx; k, hyoid bones ; t, thyroid car-
tilage ; c, cricoid cartilage ; ar, arytsenoid cartilages ; v, ventricle of the
glottis and of the larynx, formed as described in the text ; e, epiglottis ; tr,
trachea.

Fig. 113. Larynx, front view ; the contour of the inner wall is indicated by
the dotted lines aa, bb : li, true vocal cords, or inferior ; Is, false ditto, or
superior. The other parts are indicated by the same letters as in the pre-
ceding figures.

158

ZOOLOGY.

Fig. 114.*

§ 300. Most physiologists are disposed to think that the
voice is solely produced by the vibrations of the true vocal
cords acting in the manner of the reed of the hautboy ; this
would make of the human organ of voice a wind instrument.

Others speak of it as if it more
resembled the violin, or was
a stringed instrument. The
human voice, which surpasses
all musical instruments, par-
takes seemingly of the quali-
ties of both kinds of instru-
ments. It has been proved
experimentally on the living
and dead larynx, that the
elastic cords (true ligaments
of the glottis) vibrate strongly
whilst the voice is being pro-
duced, and that the aperture
between them becomes much
contracted during the execu-
tion of acute or shrill sounds ;
they may even be made to touch for a large part of their
course. They differ also in length in man and woman, and
in children.

§ 301. The intensity of the voice depends partly on the
force with which the air is expelled from the lungs, partly on
the size of various parts of the larynx, partly on the facility
with which its various parts vibrate. In some mammals,
large cells exist, communicating with the larynx, and it is to
these cells that the strength of the voice is attributed. This
structure is met with in the ass, and more especially in the
apes of America, called howlers.

§ 302. The timbre (quality) of the voice seems to depend
partly on the physical properties of the ligaments of the
glottis and walls of the larynx, partly on those of the air-tube
following the larynx. The quality, for example, of musical
instruments is known to vary much, according as they are
constructed of wood, metal, or of other substances ; and cer-
tain modifications of the voice seem to be referable to a
hardening of the tissues composing the larynx, and especially

* To show the rima of the glottis and the true vocal cords : — d, epiglottis ;
c c, the two ary taenoid cartilages ; e et true vocal cords ; between them is
the rima glottidis.

OF THE INTELLIGENCE AND OF INSTINCT. 159

the cartilages. In women and children these cartilages are
soft and flexible ; whilst in men, and in women with a mascu-
line voice, these cartilages have become ossified.

The form and direction of the passages through which the
air passes after having escaped beyond the rima glottidis,
affect also the character of the voice. Thus, in passing
strongly through the nostrils it becomes nasal and unplea-
sant ; the form of the mouth, palate, and velum palati affect,
no doubt, the quality of the voice.

§ 303. In birds, as will be afterwards more fully explained,
the voice is formed in a supplementary larynx formed much
lower down, or in the trachea ; in singing birds this organ is
very complex.

'§ 304. Modification of the Voice. — The sounds produced
by the yocal apparatus may be divided into the cry, the song,
and the ordinary or acquired voice.

The cry is the only sound which most animals can pro-
duce. It is not modulated, and is generally sharp and dis-
agreeable. The cry of man is instinctive, and not generally a
voluntary act. It is quite peculiar when it expresses agony
or distress. The child can only cry, and it is by imitation of
his fellows as he grows up that he learns the art of modu-
lating his voice so as to produce articulate sounds. This
acquired voice differs from the instinctive cry, but is essen-
tially formed in the same way, that is, by sounds whose
intervals and harmonic relations are imperceptible to the ear,
at least clearly and distinctly. Singing, on the contrary, is
composed of appreciable or musical sounds, of which the
oscillations are regular, and may, as it were, be reckoned by
the ear.

§ 305. Man also possesses the remarkable power of articu-
lating the sounds of his voice, and this act is called pro-
nunciation.

The organs of pronunciation are the pharynx, the nasal
fossae, and the various parts of the mouth. But man is not the
only animal which has this power, although he is the only one
who knows how to attach meaning to the words he pro-
nounces, and to the arrangement he gives them ; he alone is
gifted with the power of speech.

OF THE INTELLIGENCE AND OF INSTINCT.

§ 306. Having examined the organs by which man and

160 ZOOLOGY.

other animals acquire their knowledge, there remains the
study of the power which determines their actions and the
phenomena of the understanding. This hranch of physiology
having been more cultivated by philosophers than naturalists,
we shall confine our remarks thereon to a brief space.

It is man alone who possesses the faculties we allude to in
a high order, and it is man who naturally has been most
observed in this respect; our comparisons have reference
constantly to man ; by him we judge of other animals.

§ 307. Faculties of the Human Understanding. — Im-
pressions made on the external senses by the external world
are transmitted to the brain by the nerves : they are then
called sensations. Sensation, then, is quite distinct from an
impression ; it is an impression perceived ; it implies con-
sciousness ; what is not perceived has no existence, for us.
The perceiving faculty is usually spoken of as the mind, the
spirit (esprit), the soul ; the thinking, perceiving, and reflect-
ing power, conscious of its own independent existence.

§ 308. Over this consciousness we have no power during
sleep, but when awake we can direct it to one object to the
exclusion of others. When thus forcibly and strongly called
on by one impression, pain ceases to be felt, and the external
world is no longer observed. This faculty is called the power
of attention, which varies almost in every individual.

§ 309. The constant relation of certain sensations to cer-
tain impressions leads to the inference that the one causes
the other ; that the one is the effect, the other the cause. We
arrive at this conclusion by the natural powers of induction.
We thus acquire a knowledge of the external world, and we
learn to judge by comparison of the different qualities of
objects.

Soon the mind does not stop at this point, but proceeds to
weigh more and more carefully the impressions and sensations
thus received; the faculty of judging and, (comparing becomes
rapid and surer ; it is not the senses which are exercised, it
is the judgment ; the organs of sense require no education.
And here man's faculties would stop, were it not for another
faculty, by which sensations long since received can be re-
called, and compared with each other and with those then and
there present.

§ 310. This faculty is the memory ; by its means we
recal the sensations, more or less vividly, more or less ac-
curately, according to our natural powers of perception. The

OF THE INTELLIGENCE AND OF INSTINCT. 161

power varies almost in every person. It may be destroyed
by disease or strengthened (?) by exercise : active in youth, it
becomes dull with age, especially as regards the events of
yesterday, whilst the sensations of youth are readily recalled,
even in extreme old age. Youth, then, is the age for acquiring
knowledge.

Nothing is more capricious than this faculty called memory;
it would seem as if there were so many distinct memories,
which different men possess in various degrees. Some have
a memory for words, others for dates, others for language, in
its largest sense ; and by disease one of these memories may
be destroyed and not the others. But there exist no good
grounds for supposing that there really exist more memories
than one.

§ 311. By the faculty of * judgment we compare the sensa-
tions derived from all sources with each other, study their
relations and draw from them certain conclusions or opinions.;
and it is this faculty which especially characterizes man from
all that lives. By reflection he studies his own faculties,
and, when it is sound, measures them accurately with others.

§ 312. The imagination is a faculty which plays an im-
portant part in the phenomena of the human intelligence ; it
is connected with the power we have of creating signs to
represent our ideas.

§ 313. Finally, the will, without which our other faculties
were given to no purpose ; the will, by which we seek plea-
sure and safety, and avoid pain and danger. With this,
however, there is joined a tendency to induction, and, super-
added as it were, the sentiment of justice, of the beautiful,
of pity ; in a word, all the moral sentiments so peculiarly
human, and which, though general, men possess in such varied
degrees.

§ 314. These faculties have strong affinities with others,
which may be named affective, such as parental and filial
affection for our fellow-creatures, &c.; and these, on the other
hand, have strong affinities with our natural instincts. In
man, these instincts are but little developed, compared with
what we find in other animals, in whom they play a most
important part.

§ 315. Principles of Actions. — The various faculties we
have just enumerated are the determining cause of most of
our actions.

§ 316. Certain actions, as those of the heart and intes-
M

162 ZOOLOGY.

tines, called peristaltic, are automatic, that is, they are alto-
gether independent of our will. Other movements are semi-
automatic, as the respiratory, and the force which determines
these seems to reside in the spinal marrow (§ 255).

The effects of hahit and of the association of ideas form an
interesting subject of psychological inquiry ; but for this we
have no space, but must remain content with merely pointing
out the analogy between the acts resulting from these and
the operations of instinct.

§ 317. Faculties of Animals. — Contrary to what might
have heen expected, the study of animal instinct is more diffi-
cult than that of the human understanding ; we have, in fact,
no means of knowing how they think and feel ; we can judge
only by the results, that is, their actions.

§ 318. All animals feel ; but in the lowest it is not easy
to perceive that the sensations they experience lead to any
act of judgment or reflection : they move to avoid an
obstacle, and that is all. The faculties of relation seem
limited to this in the infusoria and in zoophytes. But as we
ascend in the scale, acts appear in the history of animals, so
complex and so appropriate, as to force us to admit an ad-
mirable instinct to preside over these, and even a degree of
intelligence resembling, however distantly, our own. The
natural history of the beaver, the bee, and the ant, are singu-
larly instructive on this point ; whilst the intelligence of the
dog, the elephant, and the ape, has at all times attracted the
notice of man.

§ 319. Instincts of Animals. — The character which espe-
cially distinguishes instinct from reason, is, that instinctive
actions are not the result of experience or of previously acquired
knowledge through the senses, whilst those of reason can be
readily traced to that source. In man, the reason takes
almost wholly the place of instinct ; in animals it is the re-
verse. As one of the simplest examples q£ instinct, we may
cite the case of ducklings hatched and brought up by a hen.
In spite of every effort made by the supposed parent, the
duckling at once seeks the water, and boldly plunges into a
medium of which it has no experience, and into which its
adopted parent dare not follow.

As examples of instinctive acts of extreme complication, we
may cite the labours of the bee. Now bees require neither
models, nor instruction, nor experience ; they are self-taught,
and from generation to generation they labour in the same

OF THE INTELLIGENCE AND OF INSTINCT. 163

way ; but they continue also to labour (and this is why we
say "blind instinct") when their labours can be of no avail.
Such labours cannot be ascribed to any acts of intelligence,
but resemble rather those which lead the infant to the breast
of its parent.

So varied are the instincts of animals, that we could only
venture in a brief manual such as this to speak of a few —
these we shall select from amongst the more remarkable.

§ 320. The principal instinctive actions may be arranged
in three classes, according as they refer to the preservation of
the species, to that of the individual, or to its relations with
other animals.

§ 321. Of the instincts bestowed on animals by nature,
none is more remarkable than that inciting them to live ex-
clusively on certain substances. Some of the simplest ani-
mals are without instinct, and swallow whatever comes near
them : such is the case with various zoophytes ; but it is
quite otherwise with most, which refuse obstinately all sorts
of food but one. Some live exclusively on animal food, others
on vegetable ; others only on certain plants, or the leaves and
fruit of but one plant, showing an indifference for all others ;

Fig. 115. — Ant-lion.

and what is most remarkable is, that at a certain stage of
their growth they will abandon this kind of food for another,
with the use of which they were previously wholly unac-
quainted. Thus certain insects carnivorous in the larva
state, become phytivorous when perfect : and frogs, which
when tadpoles are vegetarians, become carnivorous as frogs.

§ 322. With the instinct, nature of course gives the ability
to gratify it.

M 2

164

Thus the larva of the ant-lion (Fig. 116), a small insect re-
sembling an ephemera, preys on ants and other insects, of
which it sucks the juices; but being slow of foot, it is
forced to spread traps for the capture of its prey. It digs in
the sand a small pit, in the form of a funnel (Fig. 117), in the
bottom of which it conceals itself, watching the moment
when its prey may fall unawares into it. Should the fall not
be effectual, it stuns its victim by throwing grains of sand
at it, by means of its mandibles. Its mode of procedure in
digging the pitfall is equally curious. After having examined
the ground, it traces a circle ; placing itself within this circle,
it commences digging, throwing out the sand from the
excavation as it is being formed ; this is done by means of
• the head. Thus it continues turning itself round within
the circle traced, until it returns to the point from which it
started, where, changing sides, it repeats its labour until the
pitfall be complete. Should it meet with a stone difficult to
move, it leaves it for awhile, to return to it when the rest of
its work has been accomplished ; its whole efforts are now
directed to remove the stone, but should these fail, it abandons
the entire enterprise, proceeding elsewhere to break up fresh
ground. Lastly, it repairs carefully any damage done to the
walls of the pitfall by accident.

Fig. 116.— Larva.

Fig. 117.— Pitfall of the Ant-lion.

Certain spiders, as is well known, spread nets still more
curious, to catch flies and small insects. The disposition of
the thread of the web in some is without regularity ; in
others, as in the web of the Epeira Diadema,* it presents the
utmost elegance of arrangement. Some enclose their victim,

* Aranen Diadema, Lin.

OF THE INTELLIGENCE AND OF INSTINCT.

165

in addition, with, threads of the web, so as to afford them time
to pierce it with their venomous claws.

The Archer of the Ganges, a fish living on insects, spirts
water on those he sees on aquatic herhs, and is said seldom
to miss his prey, even at the distance of several feet.

Finally, to instinct must be ascribed most of the wiles prac-
tised by quadrupeds during the chase of their prey.

Fig. 118.— Common Squirrel.

§ 323. To the same class of instincts must be referred the
cumulative or store-forming habits of certain animals. The
common squirrel furnishes us with an example of this pro-
pensity to lay up a store of provisions against a scarcity, to
be dreaded or expected in winter ; but the propensity exists
where no change of season indicates the reasonableness of
such an event. The young commence laying up store of
provisions during summer in hollows of trees, which they
readily find in winter, even though concealed with snow.
The Lagomys pika, a Siberian rodent, not only lays up a
store for the winter, but turns the grass into hay, exactly
as our farmers do, before it stores it. Under each magazine
of hay, prepared in fine weather with the greatest care
and foresight, he digs a passage to his burrow, that he

166 ZOOLOGY.

may visit each in turn, under shelter and under ground,
protected from accidents and sheltered from the inclemency
of the weather. The bee, of which we shall presently speak,
labours in this direction, laying up ample store of provisions
for winter.

§ 324. Amongst the preservative instincts, as they may
be called, is the art of constructing dwellings without either
model or instruction. The silkworm spins a cocoon, in which
it remains as a larva, until ready to become a butterfly. The
rabbit forms its warren, and the beaver its well-known habi-
tation. The hamster (Fig. 119), a small rodent analogous
to the rat, met with in the plains from Alsace to Siberia, and
which is so injurious to agriculture, constructs a dwelling
with two issues or exits ; the one oblique, by which it throws

Fig. 119.— The Hamster.

out the loose earth produced by its excavations ; the other,
perpendicular, is the way by which it enters and leaves its
dwelling. These galleries lead to a certain number of cir-
cular excavations communicating with each other by hori-
zontal passages ; one of these cells, furnished with dried grass,
is the dwelling of the hamster ; the others are intended to
serve as magazines of provisions, which it collects in consi-
derable quantities.

Some spiders (my gale) construct works like those of the
hamster, but more complicated ; for they not only construct
a vast and commodious dwelling, but know how to shut it in
by means of a covering or doorway, furnished with a hinge.
On the side opposite to the hinge are a number of small
openings, into which the animal, introducing its claws, holds
the covering secure when an enemy attempts to open it. The
exterior of the doorway of this den, as it may be called, is left

OF THE INTELLIGENCE AND OF INSTINCT.

167

Fig. 120.— Nest of the Mygale, or
Bird Spider.

rough, like the neighbouring soil, so as to elude observation ;
the pit forming the den is dug in argillaceous earth, and
lined interiorly with a kind
of extremely consistent mor-
tar, and a lid or covering
is worked with alternating
layers of miry earth and
threads reunited into a tissue,
made to fit exactly and to
open only outwards. The
hinge supporting this cover-
ing is formed by a continua-
tion of the filamentous layers
proceeding from a point of
its contour upon the walls of
the tube situated beneath it,
forming there a pad or hood,
performing the office of a
mantle-tree.

Among insects also may be observed many remarkable
instances of singular instincts in the construction of dwellings.
The larva of a small nocturnal butterfly, the tortrix viridis-
sima, is one of these ; it
lives on the oak, rolling-
up its leaves and connect-
ing them together with
threads. Others, as the
cloth moth, a small grey
and silvery papillon or
moth, which, when in the
larva state, rapidly breaks
up woollen stuffs, forming
galleries in the thickness
of the web or cloth. With
the hairs or wool thus
detached it forms long
tubes as a dwelling ; and
what is singular is, that when this becomes too small to
contain it, it breaks it open and adds to its length.

Hybernating animals show singular instincts tending to
their preservation : they prepare a winter dwelling, and shut
it in, as if conscious or aware that they would not require to
leave it for a long period ; also to protect them from the access

Fig. 121.— Nest of the Tortrix; Oak-leaf
rolling Caterpillar.

168 ZOOLOGY.

of cold and enemies. This is the case with the marmot
exhibited in the streets by Savoyard boys.

§ 325. A third class of instinctive faculties, which, like
the preceding, have a reference to the preservation of the
individual, but which at other times seem combined with the
faculty of securing to the young conditions favourable to
their existence, is exhibited by those animals which undertake
distant journeys : sometimes even to change their climate
periodically ; occasionally they merely leave the district when
they have exhausted the provisions it furnishes to them ;
sometimes it is the cold of winter which urges them towards
the south, or the heats of summer which drive them to the
north. But these journeys are always undertaken before any
atmospheric change appreciable by us happens, to warn
them of a necessity for such a change ; or, in other words,
their instinct leads them to perceive the coming event, and
directs them at once to the object sought, the region they aim
at, without the least hesitation or error. They unite in
bands, and thus proceed on their journey.

The apes of the New World change their habitat irregu-
larly ; they exhaust the resources of a district, and proceed in
search of another with loud cries, carrying their young on
their backs.

The lemmings also undertake distant journeys, seemingly
in an irregular manner, and for reasons which man cannot
discover. They inhabit the shores of the Icy Sea, and descend
occasionally from the mountains in innumerable bands. These
migrations, fortunately for the inhabitants of Sweden and
Norway, happen only about once in ten years ; for the lem-
mings travelling in straight lines, and thus crossing rivers,
rocks, and mountains, destroy all vegetation, even to the
roots and grains. Nothing diverts them from their course
but smooth walls, which they cannot cling to.

In general such journeys are periodic. A small rodent,
resembling the lemming, annually leaves I^amtschatka for the
west; they march in straight lines, and are so numerous that
when they reach the banks of the Ocholsk and of the Jou-
doma, after having traversed 25 degrees of longitude, a single
column will occupy two hours in defiling. In October, they
return to Kamtschatka, and their return is a jour defete for
the inhabitants, for the number of the carnivora which follow
them is so great as to furnish an abundance of valuable furs.
At the Cape of Good Hope and in North America are also

OF THE INTELLIGENCE AND OF INSTINCT. 169

met with, in spring time and autumn, vas't herds of antelopes
and deer, migrating to great distances.* But it is chiefly in
the class Birds that the more remarkable instances of this
migratory habit are found. A great number of these animals
pass and repass from Europe to Africa so regularly that one
may almost name the day of their probable arrival. The
swallow comes in spring and departs in autumn. At this
season they unite in troops, and may be seen collected on
some prominence of the Mediterranean shores, watching, as it
were, the favourable moment for the commencement of their
journey. They proceed sometimes as far as Senegal. The
quail also seeks in the milder regions of Africa and Asia Minor
«i winter residence ; and many northern birds migrate an-
nually towards the South, to pass the rigorous season in
milder climates, returning towards the polar regions with
early spring. The same instinct exists in fishes ; the salmon,
herring, tunny, &c., offer examples sufficiently well known.

§ 326. No less curious are the instincts which lead insects
and other animals to provide for the preservation of 'the
young. The tedious process of incubation or hatching the
eggs ; the care bestowed by the parent on the young so soon
as they appear ; the selection of the
locale ; the construction of the nest ;
the kind of education which some
give their young; the forethought
which provides for the young food .in
abundance the moment they require
it, added to the love of offspring so
strongly shown in many animals,
must always excite in every reflecting
mind the utmost admiration of the
boundless power and knowledge and
wisdom of the great Author of nature.
These instincts extend to woman
herself, and develop in her at once
all the fondness of a parent and the sagacity of womanhood.

§ 327. As many insects never see their young, these won-
derful acts arise only from instinct : many place by the side
of the larva, food adapted for its nourishment, not such as
they themselves use. The necrophore (Fig. 122), Sexton
Beetle, often met with in the fields, buries the carcase of a

* These migrations of the Antelope in Southern Africa appeared to me to
b^ chiefly regulated by the condition of the pasture. — R. K.

170

ZOOLOGY.

mole or some other 'animal near the place where it deposits
its eggs, that the young when they appear may have an
abundant supply of provisions. They live on putrid meat like
the parent ; but the pompiles, insects allied to the wasp, live,
when adult ; on vegetable food, as larvse on animal substances.
They thus provide for the young a food they do not themselves
use ; they place near the nest the body of a spider or of some
caterpillar, which they have pierced with their sting. The
xylocopa or carpenter bee (Fig. 123) has similar habits, and

Fig. 123.— Xylocopa (Carpenter Bee). Fig. 124.— Nest of the Xylocopa.

hollows out in timber a series of cells, serving at once as nests
and storehouses for its larvse.

§ 328. The adult bird seldom provides any nest or
dwelling for itself; it is for its feeble and tender young that
it labours with such skill and perseverance in the construction
of a dwelling for them when they most require it. These
nests, which vary with the species, are yet as it were identical
as regards any species, and are uniformly constructed in the
way best befitting the young of that species. They vary in
their position, in forms, and composition, but most have
a hemispheric form, the exterior formed of stalks and grass
and herbs, the interior of soft downy substances, as moss
(Fig. 125) ; but at times they are more complex. A well-
known instance is that of the baya of India, a bird of the
nature of our bullfinch ; the nest it forms resembles a bottle,
and is suspended to the branch of a tree, so that neither apes,
serpents, nor even squirrels can reach it ; the entrance to the

OF THE INTELLIGENCE AND OF INSTINCT.

171

nest, moreover, looks downwards, so that the bird can only
enter from below, and flying. It has two chambers, one for
the male, the other for the female. Another nest equally
curious is that of the Sylvia sutoria (Tailor Bird), which con-
verts the cotton of the cotton-tree into threads, and with these
sews together the leaves so as to form a nest.

Even some fishes construct a kind of coarse nest, in which
they deposit their ova ; but it is amongst insects that the
constructive power is the most remarkable ; and to this we
shall return in describing the nests of bees and wasps, and
we shall therefore conclude this brief sketch by a single
example taken from the class of solitary insects.

The Xylocopa violacea (Violet Carpenter Bee) is allied to
the family of bees. This animal (Fig. 123) hollows out
in the timber of the hedge-rows, of fruit-trees, and of vine
poles, oval holes, which at first advance obliquely, then curve

Fig. 125,— ^est of the Goldfinch.

downwards, and descend vertically for a foot or more : in
thus tunnelling the wood, the xylocopa takes care to preserve
and collect together the debris, with which it afterwards
constructs partitions, thus forming cells for lodging the larvae

172

ZOOLOGY.

and their food ; in each cell is deposited an egg, and a quan-
tity of vegetable fodder as food for the young so soon as it
may be hatched.

Fig. 126.— Nest of the Baya.

Fig. 127.— Nest of the Sylvia
Sutoria, or Tailor Bird.

§ 329. By instinct, animals lead a solitary life or live in
groups ; and these groups unite for mutual defence. Each
species has its own habits and its own relations with other
animals, with which it consorts or avoids or pursues. These
associations are sometimes permanent, v£t others only tem-
porary. The hysena and wolf unite in groups only when
pressed by hunger. Swallows also assemble for the purpose
of travelling. Still more remarkable is the so-called pigeon
of America. They collect in almost countless millions. The
celebrated American ornithologist, Wilson, calculated at
2,000,000 a single band which he saw in Indiana; and
Audubon relates that one autumn day he left his house at
Henderson, on the banks of the Ohio, and whilst traversing

OF THE INTELLIGENCE AND OF INSTINCT. 173

the uncultivated plains near Harden sburgh, he saw these wild
pigeons in considerable numbers, flying from north-west to
south-east ; as he journeyed on to Louisville the flock of birds
became more and more numerous, until the light of midday
was obscured as in an eclipse ; the droppings fell like snow ;
before sunset he arrived at Louisville, a distance of fifty-five
miles, but the flight of the migratory pigeons still went on ;
this phenomenon continued for three days ; the droppings
from the birds formed a distinct layer on the soil ; forests
were stripped of their leaves, and sometimes destroyed, and
the traces of their passage will remain for years.

Fishes and insects are also gregarious, the herring for
example, and locust ; the former assembling in vast shoals,
and the latter in such numbers as to devastate a country.

§ 330. The Psittacus infucatus is described by Levaillant
as assembing in numbers towards evening to bathe and sport
in some limpid stream, returning to the woods so soon as the
evening pastime is finished. It is this instinct of sociability
which brings together the warren rabbit and the prairie
dog of America, a small rodent, with habits resembling gene-
rally this class of animals. But it is chiefly in the beaver, the
wasp, bee, the ant, that this sociable instinct shows itself in
its utmost development ; that is, instinct directing all towards
some common labour.

§ 331. The Canadian beaver is of all animals the most
remarkable for its sociability and instinctive industry. During
summer it leads a solitary life in burrows dug by the banks
of some lake or river ; but, when winter approaches, it quits
its burrow to assemble with its fellows to construct in common
with them its winter dwelling. In a spot remarkable for its
solitude, a group of two or three hundred assemble, and dis-
play all their architectural industry. Here they select a
stream of sufficient depth as not to freeze throughout during
the winter. They begin by forming with branches of trees,
interlaced, the intervals being filled up with stones and mud,
a sloping dyke, with the convexity towards the stream ; this
dyke they crisp entirely with a thick and solid covering. The
dyke is generally eleven or twelve feet at the base. It is
strengthened annually by new works, and ultimately becomes
covered with a thick vegetation. Thus is provided a pool of
stagnant waters, or at least waters but little disturbed, in
proximity with their dwellings.

When the dyke is finished, or when the waters are smooth,

174 ZOOLOGY.

such a preliminary work is not required. The beavers
separate into a certain number of families, and commence
constructing their huts, or repairing those already built.

Fig. 128.— The Beaver.

These cabins are raised against the dyke or on the edge
of the waters, and are of an oval form ; they are constructed
in the same way as the dyke itself, of branches of trees,
strongly cemented together by a kind of puddle- work. For
this purpose they use the earth dug from under the wall or
the banks, and work it with their feet ; it does not appear
that the tail is employed for this purpose. The branches of
the trees, no matter what be their size, are readily cut through
with their sharp rodent teeth ; and when a larger trunk is
required so as to intercept the stream, they, working in
groups, divide it so that it shall fall int the most favourable
manner to be floated to its destined resting-place. Their
cabins have two floors, one under water, the other above ; the
entrance and exit are by the chamber which is under water.
Finally, all these works are carried on at night, and with
extreme rapidity. When the proximity of man hinders the
beaver from uniting in numbers sufficient to carry on those
works requiring the association of many, they no longer
build huts ; but the instinct of construction remains even in
captivity, as has been seen in beavers confined in the Garden

OF THE INTELLIGENCE AND OF INSTINCT.

175

of Plants, in Paris, as shown by their collecting bits of wood
for a work which was not to be carried through.

Perfect societies, like the one just described, are rare amongst
birds ; yet we have in the Loxia soda, a kind of sparrow of
the Cape of Good Hope, a specimen of the sociable instinct.
These birds construct their nests under a roof-work common
to the whole colony (Pig. 129).

Fig. 129. — Nest of the Republican, or Sociable Grosbeak.

The nests of wasps surprise us by the regularity and per-
fection of their construction. Wasps detach, by means of
their mandibles, parcels of old wood, which they convert into
a kind of paste resembling pasteboard, with which they con-
struct rows of hexagonal qells ; these rows are placed parallel
to each other, and at certain distances supported by pillars,
which serve also to suspend them ; finally, the whole is placed
sometimes in the air, at others in the hollow of a tree, or
even underground, according to the species, exposed or en-
closed in a common covering (Fig. 130).
**/ § 332. Community of labour is the great feature in the
history of the bee ; but the bee, in its relations to the work-

176

ZOOLOGY.

ing bee and the queen, bee, shows other instincts not less re-
markable.

The domestic bees, originally from Greece, but since spread
all over the world, live in colonies composed of ten to thirty
thousand neutral or working bees, of from six to eight hun-

Fig. 130.— Vertical Section of the gasp's Nest.

dred males called drones, and of a, single female, which seems
to reign as queen. They establish their dwellings in the
trunk of some ancient tree, or in the hive which man prepares
for them ; and to the working bees belong the labours to
which the society owes its existence. Of these, some are the
wax-gatherers, which go abroad to collect the food and the
materials for the construction of the comb ; to others, called
nurses, is assigned the task of watching over the young.

OF THE INTELLIGENCE AND OF INSTINCT. 177

The working bee for collecting the wax enters a flower, the
stamens of which are loaded with pollen. This dust attaches
itself to the brush-like hairs covering the body of the bee,
when, by rubbing itself with the brushes with which the
tarsi are furnished (Fig. 131), the insect collects it into little
parcels, which it places on small palettes, hollowed out on
the surface of its hind limbs (Fig. 132). By the aid of
mandibles the working bees also detach from the surface of
plants a resinous matter called propolis, and with it they
also charge their little baskets. Thus loaded the bees return
to deposit in the interior of the hive the materials they have
collected, to set out again in quest of more. The labour in
the interior of the hive is more complex. They begin by
closing with the propolis every fissure in the habitation, leav-
ing but one opening, of no great dimensions. They next pro-
ceed to the formation of the comb intended to lodge the
young, and to serve as store-cells for the provisions of the
community. The comb is made of wax, found in various
plants, but which is also secreted by the bees themselves in
organs situated under the abdominal rings. These combs,

Fig. 131.— Working Bee. Fig. 132.— Hinder Foot and

Leg of the Bee.

or rows, are composed of two layers of hexagonal cells, with
a pyramidal base, and suspended perpendicularly by one of
their sides. Empty spaces are left between them, to permit
of the bees reaching every part. The cells are arranged hori-
zontally, and are open at one of their extremities ; they are
all of nearly the same dimensions, but some few are called
royal, being much larger than the others, almost cylindrical,
and are destined to contain the female larvae.

Bees enclose with a covering of wax the cells containing the

178 ZOOLOGY.

honey, and they take means to strengthen the combs when
any accident threatens their safety. The males or drones do
not share in these labours, and when they are no longer of
any use to the community, the working bees sting them to
death. This carnage takes place between June and August,
and it extends even to the larvae and nymphae of the males.

The female does no work ; she is always pampered and
attended to with the utmost care by the rest of the hive.
From the time she begins to lay eggs, she becomes for the
whole colony an object of the utmost respect, and she per-
mits no rival in the hive. Should one accidentally appear,
a mortal combat ensues, which terminates fatally for one, the
other remaining sovereign of the hive. So long as she is
shut up in her habitation she lays no eggs ; but should fine
weather appear, she leaves the cell and the hive a few days
after her birth, and ascends in the air out of sight with the
males. But she soon returns to the hive, and commences
laying eggs forty-six hours afterwards. These eggs she de-
posits in cells already prepared for their use. During the
first summer these eggs are not numerous, and they become
merely working bees. During winter she ceases to lay eggs,
but so soon as spring-time returns her fecundity becomes
extreme, and in three weeks she lays more than twelve thou-
sand eggs. Towards the eleventh month of her existence she
begins to lay eggs which produce the bourdons, or males,
along with others which belong to the working class ; those
of the female come a little later. In three or four days after
the laying, the eggs are fully hatched, and there comes forth
a little larva of a whitish colour, which, having no feet, is
quite helpless ; but the working bees provide amply for it,
and furnish it with a sort of bouillie, of which the qualities
vary with the age and sex of the individual for which it is
intended ; and at the moment of the transformation of the
larva into a nymph, they shut it into its cell, closing it in
with a covering of wax. Five days after the birth of the
larva of a working bee, its nurses enclose it thus in its cell.
It now spins around its body a web of silk, and at the end of
three days changes into a nymph. Finally, after having
remained under this form during seven days and a half, it
undergoes its last metamorphosis. The males do not attain
their perfect state before the twenty-first day from the birth
of the larva, whilst the females undergo their last metamor-
phosis on the thirteenth day. By varying the food given to

OF THE INTELLIGENCE AND OF INSTINCT. 179

the larvae, the working bees, or nurses, can change them from
working bees or neutrals into females or queens. Should the
queen bee be lost, the working bees immediately set to work
and break down several ordinary cells to convert them into a
royal celL The larva of one of these cells is now fed so as to
become a queen bee. When a young queen bee has finished
its metamorphosis, and gnawed through the covering of the
cell, a great agitation may be observed in the hive. On one
side may be seen working bees, which strive, as it were, to
retain her in the royal cell by shutting up all access to it ; on
the other hand may be seen the old queen bee approaching to
endeavour to destroy her, in which attempt she is obstructed
by hosts of working bees, which endeavour to obstruct her
progress, but make no attack on her. At last, as if in a
passion, she quits the hive, and with her the greater part of
the working bees and males over whom she presided. The
young bees, too feeble to leave, remain with the young queen
bee, which now becomes the sovereign of a new colony, occu-
pying the seat of the original one. The hive which has left
with the old queen remains together, and forms a new society,
which, recommencing again all the labours we have just de-
scribed, furnishes, after a certain time, a second swarm, whose
emigration is determined by the same causes as those which
gave rise to the first. A hive gives off several swarms during
a season, but the last are always feeble. The colony some-
times breaks up on the death of the queen bee, the attacks of
enemies, or the weakness of the swarm ; but the bees thus
dispersed seek shelter in other hives, where they are uniformly
destroyed by the proprietors of the hive, for no strange bee is*
admitted into a hive in which it was not born. Sometimes,
also, a whole colony attacks another, and robs it of its stores
of provisions.

§ 333. This pillaging instinct on the part of bees resembles
what we find takes place in some other insects, but which is
manifested in a different manner. Animals of a different
species are captured and reduced to slavery. The natural
history of ants gives us the example.

These interesting insects live in colonies, composed of males,
females, and labourers. These latter are steriles, or neutrals :
they do all the necessary work, and are provided with strong
mandibles, a large head, but are without wings. Thus they
may be known from the other ants. Each species has its
own mode of procedure. Some build their houses in earth ;

N2

180 ZOOLOGY.

others in wood. The first dig in the soil a number of gal-
leries, disposed in floors. The debris rejected forms a hillock,
in which the indefatigable ants construct other dwellings, also
in floors or stages ; but sometimes, with the earth thus thrown
out, they construct galleries along branches of trees. The
ants which establish their dwellings in trees, attach them-
selves to one going to decay, and already attacked by other
insects. With their mandibles they vigorously assail the
timber, forming it into galleries and dwellings, and support-
ing these galleries with columns wherever they may be re-
quired. Should any accident happen by the falling of these
beams, the working ants hasten to repair the damage, to
drag their comrades from under the ruins, and to place them
in a secure quarter. The males and females take no part in
these labours. The first remain but a short time in the hil-
lock, and perish shortly after leaving. The females, which
have left with the males, after losing their wings, are brought
back to the ant-hillock by the working ants, placed in retired
cells, where they remain prisoners, being all the time carefully
fed and attended to by the labourers. So soon as they have
laid an egg, it is laid hold of, and removed to a separate
apartment or cell, each to its own ; — the egg which is to give
origin to a female to its own cell, and that which in time will
produce a labourer, to its particular dwelling-place. The
larvse are attended and fed with the greatest care with their
appropriate food, and carried out in fine weather to bask in
the sun. Whilst so exposed they are defended from their
enemies, and carried back in the evening to their cells, which
are kept in the very best order. Ants lay in no stock of pro-
visions, but seek day by day what they require. Whilst some
are occupied with the care of the buildings, others proceed in
quest of food. They attack the puceronS (grubs), which on
being pressed by the feet of the ant, give out a drop of sweet
liquid, which the ant carries off. But some are not content
with this, but carry with them the insects (pucerons, or grubs)
to the hillock, and retain them there, as farmers do milch-
cows. Two neighbouring or rival hillocks have been seen to
fight for the possession of these pucerons, and the conquerors
have been seen to carry off their prisoners with the same care
that they bestow on their own larvse. Finally, that which is
most singular in the history of the ant, is still to be told.
These industrious labourers seem occasionally to get tired of
their labours, as if they wished to enjoy a little repose. In

OF THE INTELLIGENCE AND OF INSTINCT.

181

this case they make war on feebler species, to procure the
larvae and the nymphs, transport them to their hillock, and
charge the slaves they have thus procured with all the labours
of the community.

§ 334. The instinct of society is in some animals united
to another natural tendency, less striking, but perhaps of
more importance to man; we allude to the disposition to
obedience in a whole flock to obey a chief, and which seems
connected with the instinct of imitation. This instinct is
remarkable in the horse and in apes.

§ 335. Faculties of the Understanding in Animals. —
Instinct, no doubt, is the determining cause of most of the
actions of animals, properly
so called ; but some of them
seem to possess a certain
amount of memory, judg-
ment, and even the faculty of
establishing certain reason-
ings but little complicated.

The faculty of memory is
obviously possessed by many
animals : the horse, the dog,
the elephant, remember kind-
nesses, and are not forgetful
of ill-treatment. Even fishes
seem to have this faculty, for
eels have been taught to re-
cognise the voice of their
keeper.

§ 336. It is even im-
possible to deny reasoning
powers to some animals.
Thus, the dog confined in a
wooden cage will continue to
attack the bars, evidently
hoping to destroy them ; but
he speedily ceases to attack
them if made of iron. When
the dog sees his master take K*. 133,-Chimpanze.

his hat, he prepares himself

for the journey, evidently anticipating what will, or may,
happen ; nor can we ascribe to any other faculty but that of
reason the conduct of the watch-dog, which every night freed

182

himself of his collar, and making for the fields, attacked and
slaughtered the sheep ; returning after the butchery, he
washed from his mouth and throat the proofs of his guilt,
and reached his home, replacing the collar, and lying down on
the straw, reposing as if nothing had happened.

A still higher development of this faculty appears to exist
in the oran and chimpanze. A young one of each of these
species (Fig. 133) attached itself to the keeper, and assumed
on a variety of occasions all the habits of a child. It reached
by means of a chair the lock which secured it in its cage ;
on this being removed by the keeper, the chimpanze put
another chair in its place. In this action we see not only
the power of acquiring knowledge by experience, but also
the ability to generalize.

§ 337. In this approach
to human intelligence in the
lower animals, the quad-
rum ana and carnivora are
foremost ;* after these come
the pachydermata, as the
elephant and horse; next,
the ruminants ; last of all
mammals, the rodents, .as
the beaver, squirrel, &c.
The squirrel cannot be
taught to recognise its own
master; the ruminant re-
cognises its master, but a
change of clothes is suffi-
cient to make it mistake
him for a stranger. Thus,
a bison, in "the Garden,"
obeyed perfectly its master,
until he happened to change
his clothes, when it attacked him impetuously; on as-

* No animal lower .than man seems to me to possess the faculty of gene-
ralization.— K. K. *

t First described by M. Isidore Geoffrey (St. Hilaire) in such a way as
to leave nothing to be desired. A controversy was raised some time ago
in this country respecting the resemblance of the brain of the gorilla to
the human brain. It was a controversy about words. They strictly re-
semble each other in all material points. The oran outan and chimpanz6
seem to me to stand higher in the scale of being than the gorilla, which is
a West African species, and dangerous to meet. Properly speaking,
there are no four-handed animals. — It. K.

Fig. 134.— The Gorilla. t

OF THE INTELLIGENCE AND OF INSTINCT. 183

suming his former dress, the bison again recognised him as
its master. Two rams living together in harmony, will, on
being shorn, attack each other as if they were perfect
strangers. The sagacity of the dog and elephant is well
known ; so also is that of the ape, but this is confined as
regards it to youth, for with age it progresses not, but often
becomes morose and savage.

§ 338. Some animals possess the power of intercommu-
nication, by means of which they express what they feel, and
make their feelings known to their comrades. Thus, certain
mammals and birds, which live in groups, sometimes place
a sentinel, which by peculiar cries warns the troop of the
approach of danger : the marmots and the flamingo do this ;
swallows seem also to have the power, by a peculiar cry, of
collecting together for mutual defence all the neighbouring
swallows, more especially when there is danger to their
young; and the observations made on bees by Huber, La-
treille, and other naturalists, leave little doubt that these
insects have the power of intercommunication. This is
seemingly not effected by any sound, but by touching each
other with their heads and antennae, and on this being
done, thousands will crowd to the point of danger. In the
obstinate wars which one colony of ants will sometimes carry
on against another, individual ants have been seen thus to
give such signals as to change the route of a whole army;
and observers worthy of every credit assure us, that indi-
vidual ants have been seen to quit the main body, and repair-
ing to the hillock, return with strong reinforcements.

§ 339. But if the faculties we have spoken of explain more
or less satisfactorily the actions of man and animals, there
are others which, in the existing state of our knowledge,
admit of no explanation, and which lead us to suppose that
such animals possess organs of sense of a kind unknown to
us. Neither instinct nor intelligence can explain the course
of the swallow and carrier-pigeon, transported hundreds of
miles from their locality, towards which they fly, when let
loose, in a line as straight as if it lay before their eyes. The
dog and horse seem to retrace their course, when lost,
by the ordinary senses ; but this cannot be the case with the
carrier-pigeon flying in a straight line from Bordeaux to
Brussels. •

§ 340. Relations between the Intellect and the Brain. —
We know nothing of the cause why certain intellectual and

184 ZOOLOGY.

instinctive faculties are present or absent in certain animals,
nor of the mechanism by means of which the faculties are exer-
cised; all we know is, that it is by means of the nervous system
that all these faculties are exercised. When the action of the
brain is suspended, we lose the consciousness of our existence,
and with it all the intellectual faculties : the organic life then
alone remains: thus the brain is proved to be the organ
of all intellectuality, and the centre of " the life of relation."
Since nothing is known as to the nature of thought, we are
of necessity compelled to refer it to an immortal principle in
man called the soul ; in other animals, the vital principle seems
to take its place.

§ 341. The brain being admitted to be the instrument by
which the intellectual faculties are exercised, it is natural
to suppose that its structure, or at least its structural arrange-
ments, will be modified in different animals ; and this is what
we find takes place.

§ 342. Generally speaking, the power of an organ, all
things being equal, is in the direct ratio of its bulk ; and to
a certain extent this holds true, when we compare the brain
of man with the quadrumana, carnivora, and rodents; in
fishes, animals low in the intellectual scale, the brain is com-
paratively very small and simple.

This led to the idea, that the amount of intelligence in
man and animals might be measured by the size of the brain,
and the facial angle, invented by Camper, was used with this
view.*

A horizontal line (c d, Fig. 135) is represented as passing
by the auditory canal and floor
of the nasal fossae ; a second
line, b a, is let fall on the first
so as to intersect it ; the angle
formed at the point where these
lines intersect each other will
d be found to measure, by its
approach to a right or an
obtuse angle, the development
of the cranium anteriorly, as
compared with the size and
protrusion of the face. The
angle is called the facial angle of Camper.

* It is calculated to show the relative size of the cranium as compared
with the face ; but Camper did not employ it with this view.— E. K.

OF THE INTELLIGENCE AND OF INSTINCT.

185

In the antique busts, and in some living heads, this angle
amounts to a right angle ; but in most European crania, it
does not exceed 80° (Fig. 135) ; in negroes, about 70° (Fig.
136) ; in various kinds of apes, a

from 65° to 30° (Fig. 137);
in the lower mammals it be-
comes still more acute, as may
be seen by referring to Fig.
138 ; finally, in birds, reptiles,
and fishes, it becomes still more
acute than in mammals.

This coincidence between the
inclination of the facial angle Fig. 136.

and the intellectual faculties,

did not escape the ancient sculptors ; and they even exagge-
rated the angle in some of their busts.

Fig. 137.— Cranium of the
Barbary Ape.

Fig. 138.— Cranium of the Wild
Boar.

[But it is not safe, in a scientific point of view, to attach much
importance to such measurements, for the presence of the frontal
sinuses, so large in many animals, as in the owl and elephant,
and even in man himself, may lead to grave errors in respect
of that which is really aimed at, — namely, to discover the ratio
of the area of the cerebral cavity to that of the face ; and by
inference, the relative size of the brain, or of all the central
organs situated within the head, to the capacity of the cavities
for containing the organs of sense. — R. ~K. ]

[§ 343. Daily observation shows how variously the intel-
lectual faculties of individuals are modified : to some are given
a brilliant imagination ; to others, great powers of calculation :
with some, generalization is easy ; with others, difficult or impos-
sible. The senses also are quite distinct in these respects ; and
hence, in all ages, attempts have been made to discover in the
form of the head, physical characters by which these various

186

ZOOLOGY.

modifications might be detected and foretold. This led to the
theory, that the brain is not exactly one organ, but an assemblage
of many, to each of which was assigned its own functions, its
own share in the phenomena of the intellectual and social life of
man. On this doctrine was founded the celebrated phrenological
doctrine of Gall, who endeavoured, by the inspection of the
cranium, to decide on human character. Certain singular facts
and coincidences appeared to favour this doctrine of the locali-

Fig. 139.— Kespective Dimensions of the Cranium and Face.*

zation of the human intellectual faculties, but others equally
remarkable are quite opposed to it.

With regard to the instinctive faculties, which are so remark-
able in some of the lowest animals, no relation can be discovered

* Vertical section of the cranium and upper jaw, left side, seen from
within. Besides showing the anatomical details of these extensive and com-
plex osseous surf aces, the section is a valuable one, physiologically : it enables
the student to compare the area of the cerebral and cerebellar cavities with
the area of the face, or at least of the upper jaw ; the relation therefore which
the encephalon has to the organs of sense. It displays also the position of
the brain to the face, pharynx, and vertebral column, although these last are
not present in the figure. — d, the osseous palate ; et inferior meatus of the
nostrils ; m, middle meatus ; I, a portion of the perpendicular lamina of the
ethmoid ; a, points to the frontal sinuses ; c, crista galli ; k, grooves for the
branches of the middle meningeal artery ; J, posterior clinoid processes ;
h, foramen ovale ; i, groove for the left lateral sinus ; s, is placed near the
section of the foramen magnum ; f, styloid process of the temporal bone. —
From the Manual of Anatomy, by R. Knox.

OF THE INTELLIGENCE AND OF INSTINCT.

187

between these faculties and the conformation of their nervous
systems, calculated in any way to explain the phenomena ; nor
is it possible to admit, that were such relations traced to certain
structures in vertebrate animals, as the swallow, the beaver, &c.
(which has not been done), the same would apply to the inver-
tebrate kingdom, equally, if not more singularly provided with
instinctive faculties, and in which the central organs of the
nervous system, the brain and spinal marrow, are represented
by a chain of ganglions.]

[The following observations, taken from my Manual of Human
Anatomy, will explain, though very briefly, to the student, what
has been done subsequently to the time of Camper on this difficult
question. I have not alluded to the memoir of my most distin-
guished friend Tiedemann, who endeavoured to decide the same
question by filling the interior of the skull with fine sand, and
comparing the results derived from the admeasurements of
different races of men. — R. K.

"This is a psychological question not as yet decided. Attempts
have been made in various ways to arrive at some approximation
as to the mere facts, independent of all theory, but even these
have not been very successful. The first proposal was the
method of Camper, hence called Camper's facial angle ; a mere

Fig. 140.— Profile of Negro, European, and Oran Outan.

artistic view, leading to no important results. Next followed
the vertical view of Blumenbach ; then the basial ; lastly, the
vertical, proposed by Cuvier, in which the cranium and face are

188 ZOOLOGY.

divided vertically with a saw into two equal parts. Gerdy has
shown that Camper's views have been wholly mistaken by nearly
all subsequent writers. These are physiological questions, con-
nected more with philosophic and transcendental anatomy than
with the descriptive anatomy of adult man, the main object of
this work." — From the Manual of Human Anatomy, by Dr.
Knox. London : 1843.]

[Many later systems of cranial admeasurement have been
proposed since the time of Camper. The line proposed by the
Abbs' Frere, drawn from the junction of the coronal and sagittal
sutures to the meatus, is often used as the perpendicular line.
Another perhaps more convenient method, adopted in this work,
is the horizontal line which is drawn from the glabella to the
occipital protuberance. The true axis of the skull, however, is
the longitudo racheos of Von Baer, a line drawn through the
centres of the various cranial vertebrae. Professor Huxley con-
siders the basicranial axis to be the line drawn from the anterior
margin of the foramen magnum to the anterior extremity of the
presphenoid bone. — C. C. B.]

END OF PART I.

ON THE

CONFORMATION, CLASSIFICATION, AND GEOGRAPHICAL
DISTRIBUTION OF ANIMALS,

CONSIDERATION OF THE GENERAL PLAN FOLLOWED BY
NATURE IN THE ORGANIZATION OF ANIMALS.

§ 844. THE object of the present Part is to examine the
plan agreeable to which each animal is formed, and to observe
how life is modified in the various classes of these beings.

§ 345. Nothing is more varied than the conformation of
the various animals which people the surface of the earth ;
and there exists no less diversity in the various acts by which
life is manifested in these animal machines. In some the
functions are few, and the sphere of their physiological
activity very restricted ; in others the faculties are extremely
varied, and their actions multiplied in the highest degree;
and to express this difference in the nature of animals, it is
usual to say that some are more elevated, more perfect, than
others. In this way and in this view we say that a fish is
more elevated in the animal scale than an oyster ; a dog more
than a fish ; a man more so than the dog.

§ 346. Tendency to the Localization of Functions, and
to the Division of the Physiological Phenomena. — The prin-
ciple which nature seems to have adopted in the perfecting
of animals, is one which has been found to exercise the most
beneficial influence over human progress ; it is, the division
of labour. Thus, when we compare animals with each other,
differing in the number and extent of their faculties, we shall
find that the perfecting of these beings coincides with a
localization more and more marked in their functions : when
the same instrument serves for the production of several
phenomena, the physiological result is, as it were, gross and
imperfect ; and an organ always performs its part better as it
is more specialized. Now the mode of action of an organ or
instrument, in the sense we allude to, depends always on its
intimate nature, or its structure, and other qualities; and

190

ZOOLOGY.

consequently, the more organs there are endowed with
peculiar or specific kinds of activity, differing from each
other, the more numerous will be the number of dissimilar
parts in the animal economy ; and the complication more
or less great in the acts and faculties of animals must
proceed, pari passu, with the natural complication of their
organization.

§ 347. Thus in those animals in which the faculties are the
most limited, and in which life exhibits itself in its simplest
form, the body presents everywhere the same structure.
There is in fact a seeming identity of organization throughout.
Every part of the body performs the same functions as the

neighbouring parts. If di-
vided into segments, "each
part lives, and becomes an
independent animal as com-
plete as that from which it
was violently separated.

The fresh -water polyp or
hydra is an animal of this
kind. By mutilation it is
multiplied instead of being
destroyed. We owe the dis-
covery of these curious facts
to Trembley, a Swiss natu-
ralist of the last century.

The simplicity of the orga-
nization of these animals can
only be demonstrated by the
microscope, under which the
substance of their body ap-

Fig.Ml.-Hydra; Fresh-Water Pe?rs thljpughout identical;
Polyp.* it is composed of a gelatinous

mass, enclosing fibrils and

globules extremely minute. Now identity of structure would
imply identity of function, and the experiments of Trembley
proved the correctness of the inference.

* In Figure 141 several polyps are represented as attached to water-
lentils, a; they consist of a single gelatinous tube, open at one of its
extremities, and furnished with a circle of filaments called tentacula, by
means of which they introduce into their bodies the food they require. One
of these polyps, b, carries on the sides of its body two small ones which spring
from it, and will soon be detached. In Fig. 4 (p. 19) may be seen one of these
animals magnified still more than the above, to show its internal confor-
mation.

OBGANIZATION OF ANIMALS. 191

§ 348. But as we ascend in the scale, we find that this
simplicity of structure is confined to a very few species, and
that the functions become more and more localized and
specialized ; and, with this specialization, more and more
varied and perfect.

A first degree in this localization of physiological phe-
nomena, is found in the earth-worm (lumbricus terrestris),
whose body offers a series of segments of identical parts ; that
is, in each segment we find a portion of the alimentary canal,
nervous system, and circulation; but these segments are
identical, or repetitions of each other, presenting no special
organ on which life in a peculiar way depends ; and thus, if
divided into five, ten, or twenty segments, each segment will
continue to live and become an independent being.

But, for obvious reasons, this cannot be done with an
animal in which the organs have become so specialized
that on the integrity of some localized distinct segment,
not common to all, the general vitality of the being
depends.

§ 349. Already in insects we distinguish a more conside-
rable division of labour in respect of the organs ; the faculty
of perceiving certain sensations and of producing voluntary
motions, comes to be concentrated in certain nervous ganglions
lodged in the head; this concentration of functions goes on
increasing as we ascend, and embraces nearly the whole range
of the animal economy, ascending through the various
animals to man himself. Now it must be obvious that the-
destruction of one of these specialized organs, located in a
single segment of the body, and all-important to life, must
entail the destruction of the animal.

§ 350. Organic Transformations and Tendency to Uni-
formity of Composition. — The complication in structure as
we ascend in the scale of being, takes place in some instances
by the creation of organs completely new, which are thus
superadded to those already existing in the lower animals ;
but more frequently the complication is effected in another,
and, as it would seem, a much more economic way. Thus,
in a great number of instances, the localization of the func-
tions is determined by a simple modification in the disposition
of parts already existing in the lower animals, — a modification
by which these materials are adapted to the special purpose or
use, and not to a general one. In the Molucca crab (Limulus,
Fig. 142), the limbs of the cephalic and thoracic portions of the

192

ZOOLOGY.

body immediately surround the mouth, and are so constructed
as to form instruments of locomotion, instruments of pre-
hension by their free extremities, and of jaws by their base ;
but, as might be anticipated, this very cumulation of func-
tions renders them less appropriate for the advantageous
performance of any special function. But in animals of the
same class with faculties more perfect, these different func-

•'1 'V

Fig. 142. — Limulus.* (Molucca Grab.)

tions are no longer performed by one and the same organ or
instrument ; each function belongs to a distinct organ, and
yet these organs are still the same limbs or members, of
which some are exclusively destined to mastication, others to
prehension, and others to locomotion. In the craw-fish (ecre-
visse), or lobster, for example (Fig. 143), the limbs sur-
rounding the mouth are exclusively arranged for mastication;

* The animal is represented as seen from below : — J, the mouth ; />, feet
whose base performs the office of jaws j a, abdominal appendages carrying
branches ; qy caudal stylet.

ORGANIZATION OF ANIMALS. 193

another pair, unfitted for such a function, here become the
special organs of prehension ; a third series of members or
limbs is devoted to locomotion only, and of these, some are
used only in swimming, others in walking on the firm
ground.

This tendency on the part of nature to appropriate the
same part of the animal economy to different functions,
according to the wants of the animal, rather than to create
for each species parts entirely new, reveals itself also when
we compare with each other species destined to live differently.
Already in the vertebrata we have seen how, out of the same
elements, nature constructs a limb or arm, an instrument of
prehension or one of mere locomotion and support, a fin or
wing (§ 200, &c.). Such adaptations are no less curious in
insects, to which we shall return ; we limit ourselves here to
the remark, that anatomists give the name of analogues, or
analogous parts, to the organs which, however varied may be
their uses in the economy, are yet obviously composed of the
same anatomical elements.

§ 351. It is in general by means of such transformations
that nature varies most the structure of animals. She seems
to have been desirous of producing the greatest variety pos-
sible with the smallest elementary means essentially dif-
ferent : and to have had recourse to the creation of parts
entirely new only after having exhausted the combinations to
which parts already existing in other organisms could lend
themselves. This disposition is connected with another ten-
dency,— namely, the tendency to uniformity of the organic
composition. It would be absurd to assert that all beings
are formed upon one plan, and constructed out of the same
materials ; but if we examine the structure of one of the
more complex organisms, we shall find that the lower are
characterized by a modification of the larger features of the
former, by an omission of some parts, or by the existence of
organs of which the former have been deprived. A frog, for
example, differs greatly from man, and yet in its general
outline may easily be traced the indications of the plan
upon which man has been constructed. When the entire
animal kingdom is contemplated, it becomes impossible to
perceive this unity of plan and of organization ; but, by restrict-
ing the field of view, it becomes evident that, notwithstanding
the immense number of animals, all have been constructed
upon a few primitive types. Now, it is by the consideration
o

194

ZOOLOGY..

of these primitive types that the leading divisions of the
animal kingdom are established.

§ 352. Natura nonfacii saltum, was the ancient adage:
its truth is exemplified by the history of the animal kingdom.

Fig. 143.— Crawfish.*

Fig. 144. — Masticatory Apparatus.

The change from one form of organization to another is never
sudden, but, on the contrary, takes place gradually, and as it
were by shades of difference.

* Fig. 143. The lobster, or crawfish, seen from below :— a, antennae of the
first pair; b, antennae of the second pair; c, the eyes; d, the auditory
tubercle ; e, mandible feet, external ; f, thoracic feet of the first pair ; g,
thoracic feet of the fifth pair ; h, false abdominal feet; i, caudal fin ; j, anus.

Fig. 144. The six pairs of limbs which compose the masticatory apparatus
of the lobster or craw-fish ; a, mandibles ; b, c, first and second pairs of
jaws ; d, e,f, the three pairs of auxiliary jaws or foot-mandibles.

OBGANIZATION OF ANIMALS. 195

It were easy to give many illustrations of this fact: two
distinct plans of organization are obvious in the lizard and
the carp ; they differ in the general conformation of the body,
their kind of life, their mode of respiration and circulation ;
but the salamanders, the axolotls (Fig. 145), the lepidosirens

Fig. 145. The Axolotl, of Mexico. (Siren pisciforme.)

(Fig. 146), and some other animals, present us with modes
of organization intermediate to these two types, and establish
transitions so gradual from one to the other as to make it
difficult to determine whether the animal in question be a
batrachian or a fish. These transitions from one animal to

Fig. 146.— The Lepidosiren. (Potnpterus.)

another are not limited to the comparing of two distinct
adult animals ; they may be observed in comparing the same
animal at different stages of its growth or development.
Frogs, for example, present at birth nearly all the characte-
o 2

196

ZOOLOGY.

ristics of a fish, acquiring only, as they grow up, those of the
reptile (Figs. 147 to 151).

Now these transitory states of the same individual present
frequently a remarkable resemblance to the permanent condi-
tion of other species ; and hence it results that the study of
these zoological transitions conducts us not only to a know-
ledge of a sort of parentage or relationship between animals
with forms often extremely unlike, but presents us with a philo-
sophic interest of a higher order, for it seems to give us some
ideas of the course followed by the Creator of all things in the
formation of the so varied products of the animal kingdom.

§ 353. Out of this tendency to fill up all links in the
animal kingdom, there arises the notion of a series or chain
of animal life, each form graduating as it were into that

Fig. 147.

Fig. 148.

Fig. 149. Fig. 150.

Figs. 147 to 151. — Metamorphoses of the Frog.

Fig. 151.

preceding and that to follow. Sometimes, however, the link
seems broken, and there is an interruption between two types,
as if a part of the chain were lost or not filled in. Birds, for
example, seem isolated; but, generally, the deficient link or
hiatus may be found in the fossil remains with which the
globe abounds — remains of animals, species, and genera which
have now ceased to exist.

Some naturalists have thought that the series or line has
always been one uninterrupted series in the same direction,
from the monad up to man : they have attempted to establish
a zoological scale with these views; but this effort has failed,
for the series of animals is not single. Animals appear
rather to form a great number of series, which seem some-
times to proceed in parallel lines, sometimes to diverge and
rise to different elevations. It is even impossible to arrange

ORGANIZATION OF ANIMALS. 197

them in a single line according to the relative degrees of
complication and of perfection introduced by nature into their
structure, for these perfections have reference sometimes to
one organ sometimes to another ; and a species which, in
respect of the functions of nutrition for example, might be
much superior to another, may yet be greatly inferior to that
species in the organs of locomotion. As we ascend, it is true,
in the animal scale, from the monad to man, we remark, no
doubt, a progressive complication ; and it is easy to see that
the mollusks are superior to the zoophytes, fishes to the mol-
lusks, reptiles to fishes, and birds to reptiles : above all come
mammals. But a closer observation shows that this gradation
exists only between the animals which may be considered as
the types of each of these groups ; and it often happens that
certain species of an inferior group possess a structure and
faculties more perfect than the lowest species of a group of
which the chief representatives possess an organization much
more complex than that of all the former. Thus there are fishes,
as certain lampreys^ for example, which are in many respects
much inferior to mollusks such as the sepia, but these in
some measure are exceptions ; and when we trace with a bold
outline the grand picture of nature, it is allowable to neglect
these, as we overlook or neglect to observe the lesser in-
equalities of the soil when we desire to perceive at once the
general configuration of a chain of mountains. More serious
obstacles arise to the linear arrangement of animals, from
the diversity of routes followed by nature in her ascending
march, and from her tendency to perfect gradually each of
the types she has produced. Thus insects can neither be
placed before nor after the mollusks without violating some
of the most evident zoological relations ; and if we really
desire to express by a figure the relationship of animals, it
cannot be to a scale or ladder to which the animal kingdom
is to be compared, but to a river, which, weak at its source,
increases little by little as it approaches the sea, rolling not
all its waters in the same bed, but dividing often into branches
more or less numerous, which, sometimes reuniting after a
longer or shorter course, sometimes remaining from that
time forward distinct, or which at other times are lost in the
sands, and disappear for ever, or surging up once more, re-
appear at some distance, to continue their route towards the
common goal.

* [Amphioxus, the Lancelet; Myxine, the Hag-fish. C. C. B.I.

198

ZOOLOGY.

§ 354. Natural Affinities and Analogies of Structure.
-This tendency of nature to observe one general plan in the

Fig. 152.— The Human Vertebra— the Type of all Skeletons. The
references are explained below, Fig. 153.*

construction of her works leads to another sort of relation-
ship, which naturalists have called natural affinities. These
affinities are always the stronger
that they bear on organs of se-
condary physiological importance,
and necessitate less change in the
general plan of the organization.
Thus it is obvious that the lion,
cat, and tiger have strong natural
affinities; between the lion and
the dog there still exist natural
affinities, though obviously less
marked ; but between the lion
and the shark they are extremely
feeble, excepting in so far as they
both belong to the vertebrata ;
finally, between a fish and an
oyster there are none, inasmuch
as these two beings are formed on
plans essentially distinct.

§ 355. Between natural affi-
nity and analogy there is this
essential distinction, — affinities are

lis

Fig. 153.— The Ideal Vertebra,
as viewed by Oken, Spix, and
St. Hilaire as the Type of ail
Osseous Structures. f

* From the Eaces of Men, by E. Knox,

t [Copied from Owen.— c, centrum ; ns, neural spine; ks, haemal spine;
d, diapophyses ; pi, pleurapophyses ; n, neurapophyses ; ht haemapophyses ;
p, parapophyses ; z, zygapophyses.]

ORGANIZATION OF ANIMALS. 199

based on the identity, more or less complete, of the type ;
analogies, on a resemblance in the details. Thus the bat
(Fig. 108), a mammal, pterodactyle, a reptile, and the Dac-
tylopterus (106), or flying-fish, have no zoological affinity,
properly so called, excepting that they are vertebrate animals;
but they have remarkable analogies, being all organized for
flight, by having expansions of the integuments extended on
fingers prolonged for this purpose. Indeed, in contemptlating
and comparing with each other different zoological groups,
it would seem as if nature's tendency was to cause each
type to pass through a series of analogous modifications.
Thus amongst insects, spiders, and Crustacea we observe the
general plan of the organization modified in the same way,
according as the animal is intended to live on solid food, or as
a parasite by sucking the juices of another being.

§ 356. Organic Harmonies. — In the midst of the innu-
merable variety in form and structure which the animal world
presents, may be observed a certain general harmony which
$eems to regulate all the parts of this vast creation ; and this
principle of co-ordination is all the more remarkable if we
restrict our observation to the entire of the structures com-
posing a single animal. Between every part there reigns the
strictest mutual dependence, so as to forbid all idea of chance
in its construction ; all are in the strictest accord. Some of
these harmonies are so obvious and striking that the natu-
ralist may, from the observation of a single organ — a tooth
for example, deduce nearly the whole natural history of the
animal. From the subjoined figure (Fig. 154) may readily
be inferred that the animal had a skeleton,
a cerebro-spinal axis, nerves, &c. ; in short,
that it was a hot-blooded mammal, and that
it lived on flesh. In fact, from this single
organ may be deduced nearly the whole
structure of this carnivorous mammal, a
priori, or without having ever seen it. Pro-
ceeding on these principles of organic har-
monies, the true nature of the fossil organic
world was first discovered by Cuvier ; he it
was who first applied these laws to fossils, sso

and by these means effected the restoration the Lion,
of an organic world long since extinct.

[The law of organic harmonies must be applied with the
greatest caution. Cuvier seldom trusted to it ; it cannot be

200 ZOOLOGY.

made with safety the basis of a priori reasoning. — K. K. See
"Trans. Boy. Soc. of Edin.," 1829.]

§ 357. In studying this law of organic harmony, we
soon discover another, the subordination of characters. It
becomes evident that all parts of the animal economy have
not the same importance ; that certain organs may undergo
important modifications without affecting others, whilst there
are others which, when modified strongly, affect the character
of the rest. These may be called dominating organs. By
these organs the anatomist, and in some measure the natu-
ralist, must be regulated in his determinations. By the
fixity or mobility of an organ he determines its importance
in the economy.

§ 358. There are other principles regulating the great
work of creation, on which want of space forbids us to dwell.
The tendency, for example, to repetition, which leads to the
formation of homologous parts ;* the principle of connexion of
organs regulating the place occupied by each ; a tendency to
an organic balancement, equipoise, or compensation, when the
development of an organ acts as it were injuriously upon
others, as if the amount of vital force were restricted and
limited. All these subjects merit consideration, but space is
wanting to do them justice. Sufficient has been said to show
that nature proceeds always by rule and measure ; and that
the animal kingdom, so far from being a confused assemblage
of ill-assorted beings, unfolds itself to the eyes of the observer
as a vast picture, where all harmonizes and is linked together ;
finally, that the zoological laws are as simple as they are
general.f

ZOOLOGICAL CLASSIFICATIONS.

§ 359. Object and Nature of Zoological Classifications.
— Man naturally groups the various objects around him, and
he gives to these groups a different name. This tendency to
classification is one of the most remarkable of our faculties,
and powerfully aids in facilitating the operations of the mind ;
by its means we rise from the individual to the general, and
thus form generalizations and abstract ideas. It is seen in
infancy, for the child gives instinctively the same name to all

* The term homologne is with some reserved exclusively for parts
strictly representing each other in different animals. — E. K.

f See on this subject a work I have published, under the title of Introduc-
tion a la Zoologie Generate, or, Considerations on the Tendencies of Nature
in the Constitution of the Animal Kingdom.

ZOOLOGICAL CLASSIFICATIONS. 201

men that he gives to his parent, yet he does not confound the
individuals ; and, in a word, it may be said that this tendency
to classify extends throughout the whole range of our intel-
lectuality.

This necessity to reunite in our minds similar objects, and
to give to each of the groups thus formed an ideal repre-
sentative, is in fact the basis of all classification, and its
necessity is in the direct ratio of the number of objects
observed. An abstract type must represent every group.
Thus we speak of man in general, the horse, the oak, mean-
ing no man in particular, no horse, no oak; and to this
ideal representative we give the name of man, horse, oak.
But we do not stop here. Generalizing still higher, we re-
present by the word bird a vast group of living beings ; and
the terms animal or plant embrace a still higher range of
generalization ; and thus, from the remotest antiquity, men
have divided all natural bodies into three kingdoms, namely,
minerals, vegetables, and animals ; have spoken in a general
way of fishes, reptiles, &c. ; and have given to each species a
proper name.

§ 360. As science grew in its dimensions, the language of
naturalists of necessity became more precise ; for without a
precise definition there could be no science. To write the
natural history of animals, it became necessary not only to
form a great catalogue, in which each being should be desig-
nated by its proper name, but also to indicate for each of them
the characters by which they could be recognised and distin-
guished from all others. Now it was evident that, from the
conformation alone of these beings could such characters bo
drawn, those alone being constant. But there is no animal
which can be recognised by a single character, but by a re-
union of several — a reunion not to be found in any other. But
the number of animals being immense, the definition soon
degenerated into a description of the animals, to which no
memory was equal; and if we possess not the means of
arriving at this end by an easier route, the study of natural
history would for ever remain in its infancy. By establishing
among animals divisions and successive subdivisions, which
themselves are named and characterized, a great part of this
difficulty is overcome. With the assistance of a small num-
ber of characters and names, we so circumscribe the field of
comparison, that to distinguish the object before us we have
only to observe its differences from those most allied to it.

202 ZOOLOGY.

And this, in fact, is what naturalists have done. They
have divided the animal kingdom into a certain number of
groups of the first degree, each characterized by certain pecu-
liarities of structure. They next divide each of these groups,
and characterize the secondary groups thus formed in the
same manner. These secondary groups are in their turn
divided, and the sections multiplied as required, until at last
nothing is left in the same group but the different individuals
of the same species.

Classification, then, is a sort of catalogue raisonne, in
which all beings are arranged according to a certain order,
and reunited into groups, recognisable by determinate cha-
racters, which in their turn are reunited into other groups of
a still more elevated place.

§ 361. The practical utility of such classifications is easily
seen by comparing it with the address of a letter. So it is
with the naturalist, who, by his zoological classifications,
arrives speedily to the groups to which the animal belongs.
If, for example, he was desirous to define a hare, without
resorting to such means he would be forced to compare his
description to that of more than one hundred thousand ctif-
ferent animals. But if he says that the hare is a Vertebrate
animal of the class Mammalia, of the order Rodentia, of the
genus Lepus, — by the first he excludes all invertebrates from
his comparison; by the second, he excludes all reptiles, fishes,
and birds; by the third, he distinguishes the hare from nine-
tenths of these mammals ; and having thus arrived at the
genus to which it belongs, a very few distinguishing cha-
racters in addition will enable him to characterize the species
for certainty.

§ 362. Artificial and Natural Classifications. — Zoolo-
gical classifications are of two kinds, artificial and natural.
In the artificial classification of animals, the divisions are
based on modifications which certain parts of the bodies
present, and which are chosen arbitrarily ; in the natural
classification, on the contrary, the whole of the organization
of each being is taken into consideration, and then arranged
accordingly.

§ 363. An artificial system is generally of easy applica^
tion, but it often gives us no important information but the
name of the object. Suppose we take the number of the
limbs as a base for classification, we should place in the divi-
sion quadrupeds the ox, the frog, the lizard, &c., thus

ZOOLOGICAL CLASSIFICATIONS. 203

violently separating animals from their natural affinities, and
grouping together those which have none.

§ 364. Hy the natural method, the divisions and subdi-
visions of the animal kingdom are founded on the whole of
the characters furnished by each animal, arranged according
to their degree of respective importance ; thus, in knowing
the place which the animal occupies, we also know the re-
markable traits of its organization, and the manner in which
its principal functions are exercised.

§ 365. The rules to be observed in arriving at a natural
classification of the animal kingdom are of extreme simplicity,
but often there is much difficulty in the application. They
may be reduced to two, for the object of the zoologist in
establishing such a classification is, —

1st. To arrange animals into natural series, according to
the degree of respective affinities, — that is to say, to distribute
them in such a manner that the distance from, or proxi-
mity to, a species, is the measure of the resemblance or
dissemblance.

2nd. To divide and subdivide this series according to the
principle of subordination of characters, — that is to say, by
reason of the importance of the differences which these animals
present between them.

§ 366. To be satisfied, for example, of the affinity which
exists between the cat and the tiger, it is not necessary to
study the anatomy of these animals, for the external forms
translate, as it were, the character of the internal. But in a
great number of instances the examination of the internal
structure becomes necessary, in order to avoid important
errors. Thus, for a long time, the relations which exist
between the Iernsea3, parasitical animals with strange forms
(Fig. 155), which live on fishes, and the smaller Crustacea of
fresh waters, known to zoologists by the name of Cyclopes
(Fig. 157), were not understood ; because in their adult state
these two animals do not resemble each other, — but since
naturalists have studied their development they have become
convinced of their relationship, for when young they differ so
little from each other that it would be often difficult to dis-
tinguish them. (Figs. 156 and 158). Finally, to fulfil the
first of the two conditions pointed out above, it becomes neces-
sary to overcome other difficulties depending on the multi-
plicity of the relations of each animal with those surrounding
it, and of the diversity of the transitions by which nature

204

ZOOLOGY.

passes from one type to another. By reason of these circum-
stances, it is also impossible to arrange animals in a single
linear series, without violating at every instant their respective

Fig. 157.— Cyclops, one of the
Entomostraca.

Fig. 155.— Lernsea.

Fig. 158. — Larvse of the Cyclops.

affinities, and we are obliged to disperse them into several
parallel lines, or lines branching out from each other.

[Such relations being based on embryology, which again rests
on the transcendental, must be used with great caution, and
must not be mistaken for any natural generic or specific consan-
guinite between the animals forming the subject of observation.
The young of the Balanus, or acorn- shell, whilst in the larva state,
also closely resembles the Entomostraca (microscopic shell-fish)
as well as that of the Lerncece. In a philosophic sense, however,
such observations are, notwithstanding, exceedingly interesting ;
and they tend to show that animals which we have hitherto con-
sidered as adult, specific, and fully developed, may after all be
merely "arrested forms" of others passing through various
metamorphoses. — B. K.]

§ 367. The second condition in the establishment of a
natural classification is an exact relation between the suc-
cessive divisions of the animal kingdom and the importance
of the modification of structure serving as the basis to these
sections.

ZOOLOGICAL CLASSIFICATIONS. 205

The characters which distinguish animals from each other
are far from having the same value : some are of seemingly
little or no physiological importance, seeing that their varia-
tions do not draw after them differences in the rest of their
economy; others never vary without coinciding with pro-
found modifications in the whole of their organization ; hence
they are called dominating, since they seem in some measure
to regulate these modifications. It is evident, then, that divi-
sions of an inferior rank can alone he based on subordinate
characters, while those of a higher rank ought to be founded
on those called dominating. To arrive, then, at a natural
classification of animals, it is above all necessary to know the
structure, functions, and mode of development of these beings ;
next, to inquire into the dominating characters of the organi-
zation of each. This we arrive at sometimes by physiological
considerations, at other times by anatomy only. Fixity is an
index of an organic domination, whilst the characters which
vary from one small group to another, are generally but of
little* interest. The nature and the degree of development of
the faculties, of which the organ thus modified is the instru-
ment, enables us also to judge, to a certain point, of the
zoological value of a modification of structure. But in other
cases, the determination of dominating characters presents
considerable difficulties, and analogy is not always a safe
guide, for the importance of an organ may vary considerably
in passing from one animal to another, and a part which
dominates in some sort the whole economy in some species
may in others be found fallen from its rank, and reduced
to play a secondary part.

§ 368. Zoologists are far from knowing the anatomy and
physiology of all animals ; neither are they agreed on the
relative importance of a great number of modifications of
structure which animals present. It is evident, then, that in
the existing state of science there can be no natural classifica-
tion ; hence also the variety of methods adopted by different
authors, and the modifications these methods daily undergo.
But this mode of classification must of necessity become more
perfect as our knowledge extends, and its instability, far
from being a defect, is the necessary consequence of its
perfectibility.

§ 369. The introduction of natural methods of classifica-
tion of living beings is one of the greatest services rendered
to natural history ; it has changed the aspect of the science,

206 ZOOLOGY.

and given a powerful interest to that part of botany and
zoology which heretofore was the most arid.

The distinguished men to whom we owe this innovation
began with plants, which before their time were arranged
arbitrarily by the number of their stamens and pistils, or
after some other character chosen without regard to their
analogies. Towards the middle of the last age, a French
botanist, Bernard de Jussieu, conceived the happy idea of
distributing them in groups according to the whole of their
organization ; and his nephew, Antoine -Laurent de Jussieu,
applied this idea to the entire of the vegetable kingdom, and
assuming as a basis of his classification the consideration of
the dominating characters (see § 357), created the natural
method at present adopted by all naturalists.

§ 370. Mode of Division of the Animal Kingdom.—
The animal kingdom is composed only of individuals ; but
among these there is a certain number which have an
extreme resemblance to each other, and which are reproduced
with the same essential characters ; these reunions of indi-
viduals formed after the same type, constitute what naturalists
call species. Thus man, dogs, horses, form for the zoologist
so many distinct species.

Sometimes the species differs considerably from all others ;
but in general there exists a number more or less considerable
which strongly resemble each other, and which are only
distinguished by differences of little importance ; such as the
horse and the ass, the dog and the wolf. For natural
classifications, these closely allied species are reunited into
groups called genera, and to their specific name a generic
name is also added, common to them all ; thus we say the
grey, the spotted, the ocellated lizard, &c., to designate diffe-
rent species of the genus lizard ; and brown bear, white bear,
&c., for the different animals of the genus bear. Genera
which resemble each other are grouped together by the name
of tribe, or natural family.

If we afterwards consider the structure of animals in a
more general way, we cannot fail to recognise in several
families the same dominating characters, thus giving to them
in spite of their differences, a certain common character. In
this way the naturalist forms divisions of a more elevated
rank, which he calls orders, and reunites in turn these
orders into groups still more numerous, called classes.
But the classes themselves admit of being divided by the

PKIMAEY DIVISIONS AND CLASSES. 207

same principles into embr (incitements, or primary divisions of
the animal kingdom.

§ 371. Thus the animal kingdom is divided into primary
divisions, these divisions into classes, the classes into orders,
the orders into families, the families into genera, and the genera
into species; sometimes we are even obliged to multiply these
sections, but the principles are always the same : the differ-
ences which exist between two classes ought to be more
important than those existing between two families, as the
characters of families ought to have a greater value than the
characters of the genera out of which these families are com-
posed. Thus it is the more important differences which
serve for the establishment of the primary division, those of
less importance which constitute the basis for the subdivision
of these into classes, and so on, until we arrive at species or
groups, formed, as we have already said, by the assemblage of
all the individuals closely resembling each other, and which
may unite to perpetuate their race.

It is evident then, in order to class any animal in the pri-
mary division, the class, order, family, genus, and species to
which it belongs must first be determined, and that by this
determination alone we obtain precise ideas respecting all
which its organization offers of most importance, since it is
in fact these very peculiarities which serve to characterize
these successive divisions. Now, we repeat, the functions and
manners of an animal are always dependent on the mode of
conformation of its organs, or at least in harmony with its
structure, and that consequently we may deduce from this
knowledge all the most important points in the history of the
species submitted to our investigations.

Such are the bases on which rest the zoological classifi-
cations called natural. Let us now see what have been the
results of the application of these principles to the methodical
distribution of animals, and let us study the principal groups
formed by these beings.

BASES OF THE DIVISION OF THE ANIMAL KINGDOM INTO
PEIMAKY DIVISIONS (SUB-KINGDOMS) AND CLASSES.

§ 372. Primary Divisions. — Four general plans of struc-
ture, modified in a thousand ways, seem to have served as
guides for the creation of the animal kingdom. These four
principal forms may be understood by a reference to four

208

ZOOLOGY,

Fig. 159.— Asterias, or Sea Star.
*/

* This theoretical figure is intended to indicate the relative position of the
great organic apparatuses in the class mammals : — b, buccal cavity forming
the entrance of the alimentary tube, — the exit is at the posterior extremity
of the body ; i, the intestine ; ./, the liver ; t, trachea • p, lungs ; c, the
heart j e, encephalon (brain, &c.) ; m, spinal marrow.

PEIMARY DIVISIONS AND CLASSES.

209

well-known animals — the dog, the crawfish or lobster, the
snail, the asterias or sea-star (Fig. 159.)

In order that the zoological classification be a faithful
representation of the more or less important modifications
introduced into the structure of animals, it was necessary to
distribute these beings into four principal groups or divisions
and this is, in fact, what Cuvier did.

Fig. 161.— Skeleton of the African Ostrich.

The animal kingdom is divided into vertebrate animals,
articulated or annulated animals, molluscs, and zoophytes.

§ 373. The fundamental differences distinguishing these
four primary divisions depend cbiefly on the mode of arrange-
ment of the different parts of the body and on the conformation
of the nervous system. It is easy to understand the im-
portance of these two dominant characters : to feel and to

210

ZOOLOGY.

move is the especial character of animal life, and these two
functions belong to the nervous system. It might readily,
then, be anticipated that the mode of conformation of this
system would exert a powerful influence over the nature of
animals, and would furnish characters of primary importance
in classification.

The general disposition or mode of reunion of the different
parts of the body exercises an equally important influence, as
modifying the localization of the functions and the division
of the physiological result.

Although it is easy lor the zoologist to distinguish the
four groups just mentioned, and to refer to one or the other
of them an animal under examination, yet there are some
beings which seem connected with two different types, like
border lands whose rights of possession have not yet been
determined.

It sometimes also happens that it is difficult to define rigo-
rously these four groups; but, to give an exact idea, it will
be sufficient to indicate the more prominent characters pecu-
liar to each type, and to remark,
that the reunion of all these cha-
racters is not always to be met
with, sometimes one and sometimes
another being effaced as we descend
to the limits of the division.

§ 374. The vertebrate animals
resemble man in the more impor-
tant points of their structure;
almost all the parts of their bodies
are in pairs, and disposed symme-
trically on the two sides of a median
longitudinakplane ; their nervous
system is highly developed, and is
composed of nerves and ganglions,
and of a brain and spinal marrow.
To these we may add, that the
principal muscles are attached to
an internal skeleton (Fig. 161),
composed of separate pieces, con-
nected together, and disposed so as to protect the more impor-.
tant organs, and to form the passive instruments of locomotion ;
that the more important part of this skeleton forms a sheath for
the brain and spinal marrow, and results from the reunion of

Fig. 162.— Nervous System
of an Insect (Carabus, a
Beetle).

PRIMABY DIVISIONS AND CLASSES.

211

annular portions, called vertebrae; that the apparatus for the
circulation is very complete, and that the heart offers at least
two distinct reser-
voirs; thatthehlood
is red; that the limbs
are almost always
four in number, and
never more; finally,
that there exist dis-
tinct organs lodged
in the head for sight,
hearing, smell, and
taste. We have
instanced man and
thedogas specimens

of this type, but we may also include the bird, the reptile,
and the fish.

§ 375. Annulated Animals, or Entomozoaria. — In the
second primary division of the animal kingdom we find a
general mode of conformation quite different from the pre-
ceding. The body is still symmetrical and binary, as in the
vertebrate animals, but it is composed of a series of parts
which repeat each other, so that it may be divided into a
considerable number of segments, homologous [or at least

Fig. 163.— Ideal Section of the body of a
Lobster or Crawfish.*

Fig. 164. — Centipede Scolopendra.

analogous, K. K.], and more or less like each other (Fig. 164).
The nervous system is moderately developed, and is com-
posed of a double series of small medullary centres, called gan-
glions, reunited in a longitudinal chain, so as to occupy the
greater part of the length of the body (Fig. 162).

* Ideal section of the body of a lobster or crawfish :— e, the stomach,
underneath which may be seen the gullet and the mouth ; ?, intestine ; f,
the liver ; », the heart ; c, cephalic nervous ganglions situated before and
above the gullet ; g, thoracic and abdominal ganglions situated below the
alimentary canal.

p 2

212

ZOOLOGY.

The small mass formed by the first ganglions of this con-
nected chain is lodged in the head, and for this reason has
been compared to the brain of the vertebrata ; but we find
nothing resembling the spinal mar-
row, for the rest of the chain of
ganglions is situated on the ventral
surface of the body under the di-
gestive tube (Fig. 163), and the
nervous cords uniting them to the
ganglions of the head surround the
gullet like a collar. All the muscles
are attached to the skin, and there
is no internal skeleton; but the
integuments, by their hardness,
form a sort of external skeleton,
being arranged in rings more or less
moveable on each other. Thus, the
annulated or articulated character
of these animals may be seen exter-
nally; the limbs, in general, are
very numerous ; the organs of the
senses less numerous and less
perfect than in the vertebrata ; the blood is almost always
white, and the circulation very incomplete : finally a number

Fig. 165.— Section of a
Cuttlefish.*

Fig. 166. — Limnaea Stagnalis; Pond Snail.

* Ideal section of the body of a'cephalopodous mollusc (a Cuttlefish) :—
t, arms or tentacula surrounding the head ; b, the mouth ; i, the alimentary
canal ; a, the anus ; y, the liver ; c and g, nervous ganglions ; p, branchiae ;
s, the heart j v, ink-bag or vesicle ; y, the eyes.

PBIMABY DIVISIONS AND CLASSES. 213

of other peculiarities are found in the structure of these
animals, to which we shall afterwards return ; — the scolo-
pendra or centipede (Fig. 164), the lobster or crawfish, crabs,
insects, &c., are specimens of this primary division of the
animal kingdom.

§ 376. Molluscous Animals. — The molluscs have, like
the preceding, the principal organs in pairs, and symme-
trical; but the body has a tendency to assume a spiral or
curved form, so that the mouth and anus, instead of occu-
pying the two extremities of the trunk of the animal, are
more or less contiguous. The nervous system is composed
essentially of ganglions, as in the annulata ; and here also a
portion of this system occupies the dorsal aspect, and another
portion the ventral aspect, of the digestive tube ; but these
ganglions do not form a long median chain, as in the pre-
ceding division.

e d pi

Fig. 167. — Anatomy of the Snail.*

They have no skeleton internally or externally ; their body
is soft, and their skin constitutes a flexible and contractile
envelope or mantle ; it is often covered with horny or cal-

* pi, the foot ; t, tentacle, half contracted ; d, a sort of diaphragm sepa-
rating the respiratory cavity from the other viscera; e, portion of the
stomach ; f, the liver; o, the ovary; i, intestines; r, rectum; a, anus; e,
the heart, — the pericardium has been opened ; ap, pulmonary artery, rami-
fying on the walls of the pulmonary cavity p ; ar, aorta ; v, gland secreting
the viscosity; c et its excretory canal opening near the anus.

214

ZOOLOGY.

Fig. 168.— Actinia; Sea-
Anemone.

careous plates, called shells (Fig. 166), and this is sometimes
developed in its interior. In this primary division the organs
of the senses are almost always
very incomplete ; there seems to
be no special organism for smell,
and in a great number the eyes
are wanting : they have hardly
ever limbs for locomotion; and
finally, the blood is white as in
most of the annelides, but the
circulation is often much more
complete.

§ 377. Zoophytes. — Finally,
in the fourth and last primary
division, the different parts of
the body, in place of being
grouped symmetrically with reference to a median plane,
tend rather to arrange themselves around a central point or
vertical line, so as to affect a radiated disposition more or
less complete. With regard to a nervous s}^stem, no trace is
generally to be observed, and where it exists, it is reduced to
a rudimentary state; the organs of the senses are also

almost completely wanting ;
finally, all the parts of the
economy become of an ex-
treme simplicity. For a
long time they were mis-
taken for vegetables, and
hence theirnameof zoophyte
or animal-plants, and they
have been called radiated
animals, by reason of the
obvious radiated disposi-
tion of their organs. The

Fig.l69.-Talitrus; Sand-hopper. polyps, of which we have

already spoken (§ 347), the

actinise or sea-anemones (Fig. 168), and the asterias or sea-
star (Fig. 159), are specimens of this division.1*

§ 378. Subdivisions of the Primary Division into
Classes. — The animals thus arranged under a primary division

* Some zoologists admit a fifth primary division of the animal kingdom,
comprising sponges, and characterized by the absence of all regular form.
But it seems to us that this classification ought not to be adopted, for these

PEIHARY DIVISIONS AND CLASSES,

215

resemble each other sufficiently to admit of that arrangement,
but they differ in many important circumstances, and hence
their subdivision into classes.

§ 379. Thus, amongst vertebrate animals, some are born
alive, and are provided with mammae for the nourishment of

Fig. 170. — lulus ; Millipede.

their 3Toung ; others spring from an egg, in which they find
all the nutriment necessary for their constitution, and hence
are without organs of lactation ; some respire in the air,
others in the water ; in some the circulation is complete, in
others incomplete ; some have the blood hot, in others it is .

Fig. 171. — Agrion ; Dragonfly.

\

Fig. 172.— Bethylus.

called cold, comparatively : finally, some are formed to rise
into the air, others to live on the ground, and others to swim
in the depths of the waters. The differences are of a high
physiological importance, and coincide, so as to characterize
in this division five secondary types ; and hence, to class

strange animals (amorphozoaria) present when young the same characters as
polyps, only their organic development is arrested at a transitory state, and
they become deformed as they grow older. Thus by keeping in view their
mode of development, they may be referred to the class zoophytes.

216

Fig. 173.— Thelphusa. A Land-crab ; but some live in fresh water.

vertebrate animals according to the principles of the
natural method, they must be divided into five classes

Fig. 174.— The Domestic Spider.

PBIMABY DIVISIONS AND CLASSES. 217

— namely, mammals, birds, reptiles, batrackia, and

Fig. 175.— The Leech.

§ 380. In the primary division of the entomozoaria, or
annulated animals, we observe modifications of structure no

Fig. 176. — Nereis ; called b£ the Dover fishermen " the Mud-worm."

less remarkable. Sometimes, as in the talitrus, there exist
articulated limbs serving as levers in the apparatus of loco-

Fig. 177. — Kotifera ; Wheel-bearing animals.

motion ; and the cephalic portion of the ganglionary nervous
system acquires considerable importance. Sometimes, on the

«-**^^

Fig. 178. — Ascaris ; an intestinal worm.

* In the early editions of this work, the vertebrata were divided into four
classes, following Cuvier's arrangement ; the batrachia for good reasons have
since been separated from the reptilia.

218

ZOOLOGY.

contrary, as in the leech, there are no articulated limbs, the
nervous ganglions are but little developed, and present a
remarkable uniformity in structure and functions. We may
thus subdivide this primary division into two secondary
groups — namely, the articulated animals, properly so called,

Fig. 179.*

* Nervous system of the aplysia, a gasteropodous mollusc:— c, cerebroid
ganglions ; gt thoracic ganglions, or sub-cesophageal ; e, nervous collar sur-
rounding the gullet; I, labial ganglions ; v, visceral ganglion.

PRIMARY DIVISIONS AND CLASSES.

219

and the vermes or worms ; but this classification is not suf-
ficient to represent all the great differences in the nature of
these beings.

In fact, amongst the articulated animals, properly so called,
we find insects (Figs. 171 and 172) which receive the air into

Fig. 180.— Social Ascidiae.*

all parts of the economy by means of tracheae, which have the
body subdivided into three dissimilar parts — the head, the
thorax, and the abdomen, which have always three pairs of

Fig. 181.— Cypraea ; Cowry.

Fig. 182.— Shell
of the Palu-
dina ; Marsh
Snail.

feet, and which are almost always provided with wings : the
myriapoda (Fig. 170), which resemble insects by their mode
of respiration, and which have also a distinct head, but have

* Ascidise of the genus Porophora : — &, mouth ; &, stomach ; i, intestine ;
<7, anus ; t , common stalk. The arrows indicate the direction of the current
of water serving for respiration.

220

not the trunk divided into thorax and abdomen ; which have
from twenty-four to sixty pairs of feet, and even more, but
which never have wings : the spiders (Fig. 174), which have
not the head distinct from the thorax, which have always

Shell.Mantle.Tentacula. Mouth. Nerves. Muscles

Foot.

Intestine.

Stomach.

Branchite. —

Mantle.

Anterior
Ganglions.

Respiratory Tubes.
Fig. 183.— Anatomy of an Acephalous Mollusc (Mactra).

only four pairs of limbs or feet, and which respire the air like
all the preceding, but which have no tracheae, and receive the
fluid into pulmonary pouches : the Crustacea (Fig. 173), which

PBIMABY DIVISIONS AND CLASSES. 221

have, on the contrary, an aquatic and branchial respiration,
and which have always from five to seven pairs of limbs
adapted for locomotion.*

The division of vermes or worms ought to comprise also
several very distinct types. There is first the annelides
(Pig. 175), whose ganglionary system is quite distinct through-
out its whole length, with red blood generally circulating in
a very complex vascular system, in which the respiration almost
always takes place in a well- developed branchial apparatus,
and in which the movements are performed in general by
means of moveable bristles (Fig. 176) ; with these also we
arrange the rotifera, microscopic animals, which seem to
have no special organs for the circulation, and which have no
branchiae, but which have in general vibratile organs very
singular in their arrangement (Fig. 177). Finally, it is
also to this primary division that we must refer the tur-
bellaria, whose body is without limbs, and whose nervous
system is composed essentially of two lateral cords springing
from two cephalic ganglions. The intestinal worms, or
helminthise, belong also to this division ; their structure is
very simple ; they present only vestiges of a nervous sys-
tem, and yet are intimately allied to the annelides, which
often seem to be in some measure the degraded representatives
of the same zoological type.f

To place the classification of annul ated animals in harmony
with the differences which we have pointed out in the nature
of these beings, they must be divided into eight distinct
classes, the names of which we have already pointed out in
the preceding considerations.

§ 381. The primary division of the molluscous animals
presents organic modifications necessitating a similar subdivi-
sion. In the molluscs, properly so called, there is a nervous
system, composed of two or more pairs of nervous ganglions,
reunited by medullary cords (Fig. 179) ; and reproduction is
accomplished only by means of eggs. In others, which I
shall call mollusco'ides, the nervous system, reduced to a rudi-
mentary state, seems to consist of only a single ganglion, and
in most cases the multiplication of individuals takes place
by the development of granulations (bourgeons) as well as

* It has been known for some years that the cirrhipedes, which had been
formed into a particular class, ought to be restored to the class Crustacea.

f Naturalists are not agreed in respect of the classification of the entozoa,
or intestinal worms. Cuyier arranged them amongst the radiata or zoophytes ;
but they more resemble the annelides in the conformation of their bodies.

222

ZOOLOGY.

by oviparous generation; it happens therefore frequently
that individuals springing from each other remain united
together, constituting animated masses, phytoid, in fact
(Pig. 180).

The molluscoides are subdivided into two classes, according
as they have the respiratory apparatus enclosed in the mouth,
or formed by a corona or circle of long labial tentacula.
The first are called tunicata (Fig. 180) ; the second forms the
class bryozoa or polyzoa.

The mollusca, properly so called, differ amongst themselves
by characters whose importance is still very considerable.
Thus, in some the cephalic ganglions are very distant from
the abdominal ; there is no distinct head, nor trace of the
special organs of the senses ; the organs of movement are ex-
tremely imperfect, and the body is
wrapped up by cutaneous folds, pro-
tected exteriorly by a bivalve shell
(Fig. 183). Muscles, oysters, &c.,
present this mode of organization.
Other mollusca, as the snail, limnseus
(Fig. 166), and the cowry (Fig.
181), have a distinct head : their
nervous ganglions are generally close
to each other, and grouped around
the gullet ; they have eyes ; the
lower surface of the body is occu-
pied by a fleshy organ, serving for
locomotion; finally, the back is
generally protected by a shell, and
this is never bivalve, but represents
almost always a cone turned into a spiral (Fig. 182) ; others
have a distinct head like the preceding^ and on each side of
the neck a kind of membranous wing, which serves as an oar
(Fig. 184).

Finally, there are some which have the head furnished
with long contractile and prehensile appendages, performing
the functions of feet and arms (Fig. 185).

These have the nervous system more developed than in
other animals of the same primary division, and which gene-
rally have the body supported by a sort of interior shell.
Such are the various modes of conformation serving as a
basis of the division of the mollusca, properly so called, into
four classes, called acephala, gasteropoda, pteropoda, and

Fig. 184.— Hyalsea.

PRIMARY DIVISIONS AND CLASSES. 223

cephalopoda. The oyster may represent the type of the first,
that is, of the acephala ; the snail that of the gasteropoda ;
the hyalsea (Fig. 184) that of the pteropoda ; and the sepia
(Fig. 185) the group of the cephalopoda.

§ 382. Finally, the fourth and last primary division of
the animal kingdom, the zoophytes, comprises also very
varied animals, and is divided into several classes. In one of
these groups, called the class echinodermata, the body is
formed to creep on the sand or rocks at the bottom of the
sea, and for this purpose the surface is provided with a
number of small prehensile appendages; the integuments
also are of considerable consistence, and even sometimes of a
stony hardness.

The sea-stars, the holothurw, sea-cucumber (Fig. 186), and
the sea-urchins, are types of this class.

fet

Fig. 185.— The Common Sepia, or Cuttlefish.

In the second group, formed by the acalepha, the body is,
on the contrary, entirely gelatinous, and formed only for
swimming. The medusae (Fig. 188), which float in the sea
and are frequently stranded on the sandy shores of the coast,
are examples of this class of zoophytes.

In a third class, that of corallines or polyps, properly so

224

ZOOLOGY.

called (Fig. 187), there exists no longer any organ of locomo-
tion : the destiny of the animal is to live fixed to the soil, and
its mouth is surrounded with moveable tubercles (Fig. 189),

Fig. 186.— Holothuria ; Sea Cucumber.

by means of which it gathers in the surrounding waters the
corpuscles necessary to its nutrition ; in general, a portion of

Fig. 187.— The Coral Polyp.

Fig. 188. — Ehizostoma; Medusa,
or Sea Jelly.

the integuments becomes ossified, so as to form for it a kind
of calcareous or horny dwelling (Fig. 190); and in most cases
also the young spring from granulations arising on the surface

PRIMARY DIVISIONS AND CLASSES.

225

of the bodies of their parents, and as they do not become de-
tached, constitute animated masses of varied forms, resembling
a branching plant loaded with flowers.

The actiniae or sea-anemones (Fig. 168) belong to this
class ; so also does the coral polyp (Figs. 187, 189), the cary-
ophyllia (Fig. 190), &c.

Sponges (spongiarise) offer a fourth type ; these are sin-
gular animals, which, when young, have an ovoid form,
swim freely by means of the vibratile cilia with which their
bodies are provided, and resemble at this stage of their

Fig. 190.— Polyp of Ihe Genus
Caryophyllia. A Coral Polyp.

Fig. 189.— Stalk of the Coral. Fig. 191.— The Sponge.

growth the larvse of the acalephae and of the polyps : but they
soon become fixed (Fig. 191), and then lose not only their
sensibility and power of motion, but become so degraded as
to resemble nothing in the animal kingdom.

Finally, most naturalists also arrange in the division

226

ZOOLOGY.

zoophytes a fifth group, composed of an infinite number of
beings, extremely small (Fig. 192), which live in stagnant
waters, and are called infusorial animalcules. They move by
means of their vibratile cilia, and strongly resemble in
general the larvae of sponges (spongiariae), of polyps, and of
the acalepha ; but they do not change as they grow up, and
they are remarkable for their fissiparous reproduction, and
for the considerable number of stomachs hollowed out in the
interior of their bodies for the reception of food. These
beings until very lately were confounded with the systolides,
under the common name of microscopic animalcules or in-
fusoria, and in order to distinguish them they were often
called polygastric infusoria. The place they ought to
occupy in our zoological classifications has not as yet been
well determined.

Fig. 192.— Infusoria,*

Such are the more prominent characters of the principal
organic types of the animal kingdom. The sketch just given
will suffice to give the reader a general idea of the modi-
fications introduced by nature into the structure of animated
beings ; but to limit our view to this would lead to extremely
imperfect ideas of the true nature of zoology. It becomes
necessary, therefore, to examine more carefully each of the
great divisions corresponding to these fundamental differ-
ences. The subjoined tabular view, representing a synoptic
table, will assist the reader in comprising at a glance the
basis of the classification adopted in this work.

* Various polygastric infusoria, seen under the microscope : — I, monads ;
n, trachelia anas ; in, enchelis, represented at the moment when rejecting
the residue of ..the food ; iv, paramecia j v, kolpoda j vi, trachelia fasciolata,
inarching on microscopic vegetables.

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IDEAS

ON THE ORGANIZATION OF ANIMALS BELONGING

TO THE DIFFERENT CLASSES OF

THE ANIMAL KINGDOM.

DIVISION FIRST.

VERTEBRATE ANIMALS.

§ 383. The vertebrate animals,* so named by reason of
the presence of a vertebral column forming the essential part
of the skeleton, are of all animals the most perfect ; and, as
was to be expected, those also (§ 346) in whom the organs
are the most numerous and the most complex.

They possess an internal skeleton, by which means (?)
they attain a size never reached by the articulata, mollusca,
and zoophytes ; and to this skeleton may be ascribed, no
doubt, in part at least, the vigour and precision of their
movements.

This internal skeleton, to which there is nothing analogous
in the other great sections of the animal kingdom, is generally
composed of bones, and is arranged nearly as in man ; never-
theless, as in the skate, the skeleton may remain cartilaginous,
and there are fishes in which it is all but membranous. We
have already studied the skeleton carefully (§ 259 to 282).
The part which is never absent is the vertebral column and
cranium; other parts may be, and often are, deficient: the ribs
are wanting in frogs ; the sternum in serpents, &c. But it
is especially in the limbs that varieties of formation are
observable ; these are sometimes wholly absent, as in the
coluber or common snake ; sometimes they are merely dimi-

232 ZOOLOGY.

nished in number, and in aquatic animals this is observed
chiefly in respect of the posterior limbs, whilst in land animals
it is the opposite. As regards the modifications the limbs
undergo, the reader is referred to § 289 to 295, in which
sections these matters are fully treated of. The caudal por-
tion of the body being especially of use in swimming, is more
fully developed in fishes than in other animals ; important in
the action of flight, it presents a structure sufficiently con-
stant ; whilst in terrestrial animals it loses much of its im-
portance, and is not unfrequently wholly absent.

In animals low in the scale of the vertebrata, it frequently
happens that the various germs or distinct nuclei of which
the bones are originally formed do not coalesce, but remaining
distinct, cause it to appear as if the skeleton, and especially
the cranium, were formed on a more complex plan than in
the higher order of mammals. This however is not the
case, since they are all formed on one plan, the difference,
which is only seeming, not real, depending on the non-union
of the separate germs or nuclei composing the bones in every
young animal. It is in fishes and reptiles that we find this
most to prevail, and hence the difficulty of reducing the
separate pieces to their analogues in the higher animals, and
especially in man.

§ 384. It is the nervous system, and especially its central
portion, which is most highly developed in mammals ; they
surpass, probably for this reason, in sensibility and intelli-
gence all other animals.

The cerebro- spinal axis has in all the same general form
and relations as in man. Situated on the dorsal aspect of the
body, and above the digestive tube, protected by the cranium
and vertebral column, it consists uniformly of a brain, com-
posed of two hemispheres, two optic lob$s, a cerebellum, and
a spinal marrow ; these structures seem to become smaller
and more simple as we descend from man to fishes. The
nerves of relation are generally arranged as in man ; arising
or connected centrally with the cerebro-spinal axis from a
double root, on the posterior of which is a ganglion, they
form the nerves of sensation and motion, with consciousness.
The nerves of the viscera are, on the other hand, connected
with the sympathetic or ganglionary system, but this system
establishes relations with the cerebro-spinal axis by means of
numerous filaments of communication with the nerves of
sensation and motion.

OF THE CLASS MAMMALIA. 233

Finally, the organs of sense are always five in number, and
their arrangement is much as in man.

§ 385. The digestive apparatus presents hut few im-
portant differences in this great division of the animal king-
dom : the orifices of the digestive tube are always remote
from each other; the jaws move vertically or in the axis of
the body, and not laterally, as in the annulata ; the intestine
is secured in the abdomen by a mesentery (§ 45) : and the
chyle, the product of digestion, is absorbed by peculiar ves-
sels, which convey it into the veins, and thus into the mass
of blood.

§ 386. The blood, much richer in globules and redder
than in other animals, reaches the heart by the veins. It
enters an auricle, then passes into a ventricle, and by its
means is wholly or in part transmitted to the organs of res-
piration, the lungs. In general, the blood returns to the
heart before its transmission to other parts of the body ; but
sometimes it proceeds directly to these, and its circulatory
movement is determined in some cases by an auricle and
ventricle only ; in others, by two auricles assisted by one
ventricle ; and in others, by a heart composed of two auricles
and two ventricles (§ 107, 108, 109). The respiration in this
class of animals takes place in a cavity of the body internally,
but it is not always aerian,sis in man, being performed some-
times by lungs, sometimes by gills.

Of the secreting organs found in man, there are two which
are always present in the class vertebrata : these are the liver
and kidneys. The presence of a pancreas and spleen is also
very uniform.

§ 387. Nature thus seems to have followed one plan in the
construction of the vertebrata, yet they differ much from each
other, and hence the necessity for subdividing this great
primary division into five classes : namely, mammals ; birds ;
reptiles ; batrachia ; fishes.

OF THE CLASS MAMMALIA.

§ 388. This class is composed of man, and of all the ani-
mals which most nearly resemble him in the most important
points of their organization. By their proximity and utility
to man, their higher intelligence and organization, they natu-
rally place themselves at the head of all that lives.

234 ZOOLOGY.

For the most part, a mammal may readily be distinguished
from every other animal by its external characters, even by
the uneducated ; but not always, for to this day such persons
mistake a porpoise or a whale for a fish, than which there
cannot be a greater error in point of fact.

Fig. 193. — Porpoise ; Phocaena Communis.

§ 389. Development of the Function of Lactation. — That
which perhaps is the most remarkable in the history of the
mammals is their mode of lactation, by which is meant the
mode of nourishment of the young. They are viviparous,
and the young from birth depend immediately on the
nourishment they receive from the mother ; unlike the ovi-
para, which are at birth all but wholly independent of their
parent, in respect at least of nourishment.

The milk intended for the nourishment of the young is
formed of water holding in solution sugar of milk, casein,
some salts, with a little free lactic acid, holding in suspen-
sion globules of butter. Its qualities vary in different ani-
mals, and may be modified by the food of the mother. By
evaporation it leaves from ten to twelve solid parts of one
hundred.

The secreting glands of this alimentary fluid are the
mammae, of which, in the male, there exist only the rudi-
ments. They are peculiar to the class mammals, and hence
their name. Their number is in relation to that of the young.
In apes, the elephant, goat, hare, there are two ; in the cow,
horses, doe, there are lour ; in the cat, eight ; in the pig and
rabbit, ten ; in the rat, ten or twelve ; in the agouti, twelve to
fourteen. They vary also in their position : in the apes and
bats they are placed on the chest, as in woman ; in most
carnivora, they are situated on the abdomen as well as on the
thorax ; and in the mare, cow, ewe, &c., they are placed
still further back, close to the articulations of the hinder
extremities.

OF THE CLASS MAMMALIA. 235

In some the young are born with the eyes open, and are
ready at once to seek their nourishment ; but a great number
are born with the eyes closed, and in a state of great feeble-
ness, so that they can scarcely move ; and some being born as
it were before their term, could not live, were they not to
attach themselves to the tit of the mother, to which they
remain as it were suspended. In such animals generally,
thus imperfectly developed at birth, the integuments of the
lower part of the belly form a pouch in front of the mammae,
in which the young are lodged for a time. This structure

Tig. 194.— The Opossum.

characterizes the opossums of the New World, and the kan-
garoo and other marsupial animals of Australia. The young,
placed in this pouch by the mother, attach themselves each
to a nipple, and remain suspended there until sufficiently
strong to leave the pouch, to which, however, they return
as to a place of safety, until sufficiently grown to act for
themselves.

236

ZOOLOGY.

§ 390. Integuments. — In a certain number of mammals
the skin is naked — that is, it is not secured from harm by any
protecting organs, — but in the greater number we find hairs;
and so constant is this fact, that M. de Blainville proposed to
name them pilifera, in contradistinction to pennifera and
squammifera — that is, birds and fishes.

The^ hairs are formed by small secreting organs lodged in
the skin, or ^immediately beneath it. Each hair is formed in
a small ovoid pouch, with white resisting walls, communi-
cating externally by a small opening ; this pouch is termed

Fig. 195.— The Porcupine.

the capsule. The interior of this cavity is lined by a mem"
brane, sometimes reddish, sometimes diversely coloured, and
considered to be a continuation of the rete mucosum of the
^kin ; and at the lower part of this capsule is a conical papilla
or bourgeon, which receives the nerves and bloodvessels, and
which forms the hair. The substance forming the hair has
the greatest analogy to dried mucus. Under the microscope
the hairs seem to be formed of small cones or cornets, jointed
into each other j but generally they resemble a simple horny

OF THE CLASS MAMMALIA. 237

tube, filled with a pulpy matter. They vary in form, being
in most animals cylindrical, and .larger at their base than at
their summit ; in others more or less flattened or lamellated,
like sprigs of grass; sometimes their surface is smooth,
sometimes roughened with asperities, or having a moniliform
aspect ; finally, they differ in form and elasticity, not only in
different animals, but even in different parts of the same
animal.

From these circumstances, the names given the hairs differ,
being called barbs, or quills, or bristles, or simply hair. Wool
is a sort of hair, very long and tortuous ; fur is a still finer
form of hair concealed beneath a covering of ordinary hair.

The colour of the hair, which varies so much, may yet be
referred to modifications of white, black, brown-red, and
yellowish ; it seems to depend on the presence of a coloured
fat, soluble in boiling spirits of wine ; when this is extracted
by the action of the above solvent, the hair becomes of a
greyish yellow colour. In white hair a white-coloured oil
is found, and in red hair, oil of a reddish colour ; in black
hair a blackish oil, somewhat blue, from the presence of sul-
phuret of iron.* Sometimes the hairs have the same colour
throughout their whole length ; sometimes they are darker at
their base than towards their summits, and sometimes they
present a series of white and coloured rings. Moreover, their
colour varies much in different parts of the body, and the
general disposition of these tints constitutes what is nominally
called the fur (pelage). Generally the colours are much
darker towards the back, and when there are spots, these are
almost always disposed symmetrically on the sides — that is,
so long as domestication does not exercise its influence, for
then the colouring of the robe presents often the greatest
irregularity.

The fur is generally the same in both sexes, and generally
varies but little at different ages. Yet in some, the young
have spots and a variety of shades, which disappear in the
adult, and it not unfrequently happens that the colour of the
mammal changes with the seasons.

Generally the hairs fall annually, in spring time or in
autumn, to be replaced by others. This kind of moulting

* There exists also in different kinds of hair, sulphur, which may readily
combine with lead to form coloured sulphurets. It is in this way that the
hair may be dyed by the use of leaden combs, or by the application of salts
of lead, mercury, &c., the sulphuret which is then formed being of this
colour.

238 ZOOLOGY.

occasionally occurs independent of any great change in the
colour or character of the hair ; in other animals it is diffe-
rent. The common squirrel, for example (Fig. 118), whose
fur is of a deep red in summer, becomes of a fine greyish-
blue tint in winter. It is at this season that the hair of
mammals becomes much thicker, having underneath the fur
in much larger quantity. Climate also plays its part in

Fig. 196.— The Pangolin (Scaly Ant-eater), or Manis.

modifying the fur or hairy covering of the skin ; hence we
seek in cold climates chiefly for the skins of animals supply-
ing the valuable furs of commerce: Siberia and North
America are the true fur countries.

When the hairs grow extremely close together, they seem
to become matted, and to form those horny plates covering
the bodies of some mammals, as the pangolins (Fig 196) and'
the cuirass of the armadillo. Anatomists also consider nails
and horn as having the same origin.

§ 391. The Skeleton. — The general form of the body is
determined by the skeleton, but this must not be extended to
the outline in every instance ; the hump of^the camel, and the
dorsal fins of whales, are not supported internally by any por-
tion of the skeleton (Fig. 197). The skeleton presents always
the greatest analogy with the human, which we have already
studied (§ 269, &c.) The differences may be reduced, 1st.
To the absence of the abdominal limbs in the fish -shaped
mammals called cetacea (Fig 193). 2nd. In the diminution
of the number of the fingers and toes, and the absence of collar
bones in those in whom the limbs serve merely as instruments
of progression and support. 3rd. To some varieties in the
number of the vertebrae, especially of the caudal. 4th, In-
equalities in the relative size of various bones.

OF THE CLASS MAMMALIA.

239

§ 392. Conformation of the Head. — In the form of the
osseous head, the size of the cranial capacity, compared with
the area of the face, is supposed to be in the ratio of the in*
telligence, with certain exceptions ; as we recede from man,
the face becomes comparatively larger, and the cerebral cavity
smaller, proportionally to the face ; the orbits are directed
more outwards, and cease to be distinct from the temporal
fossae ; and the occipital condyles, which in man are found at
the base of the cranium, and which form the plane by which
the head rests on the vertebral column, recede more and more,
until they come to be placed almost on a line with the axis of
the body. The same happens with the jaws. Still, we find

Fig. 197.— Skeleton of the Camel. (See page 141 .)

always the same bones, the same form of articulation of the
lower jaw ; between its condyles and the temporal bone there
is no intermediate bone, as in birds, reptiles, batrachia, and
fishes.

§ 393. Various mammals are provided with horns. These

240

ZOOLOGY.

are sometimes mere appendages of the skin, and seem to be
formed of the hair matted together ; this is the case as
regards the horn or horns of the rhinoceros ; but generally it
is otherwise, and it is a prolongation of the frontal bones,
which forms the axis of these horns. All mammals provided
with such horns are ruminants. Sometimes the osseous pro-
tuberance remains covered with the common integument, and
continues so; this happens in the giraife (Fig. 271). In some,
the skin which covers the osseous core or axis disappears,
and leaves the bone exposed ; which, after being so for a time,
falls or is thrown off, to be replaced annually by another
growth : such are called antlers, and are found only in the
deer kind (Fig. 203) ; finally, in others the osseous axis is
never shed, but continues to grow during the life of the

Fig. 198. — lihmoceros of India ; a single-horned Khinoceros.

animal, covered with a kind of sheath composed of an elastic
substance, especially called horn, which grows by layers, and
is analogous to nail and hair. The term hollow horns is
given to horns thus covered with a horny sheath, formed
seemingly of agglomerated hairs, and found in different
species of the goat (Fig. 202), ox, sheep, and antelope. It
ought further to be remarked, that in all these animals, with
the exception of the antelope, the osseous axis of the horn is
hollowed out into cells communicating with the frontal

OF THE CLASS MAMMALJA. 241

sinuses, and thus receiving into their interior the external
air.

[The double-horned rhinoceros, a South African species, dis-
covered by Burchell. The
double-horned rhinoce-
ros was re- discovered by
Sparrman, after its me-
mory had been lost to
Europe since the days
of Trajan and Severus.
It was known to the
poet Martialis, who de- _.

scribed its double-horn.
But having been lost to
Europe for so many cen-
turies, commentators on
Martialis suggested that
the poet's text had been
corrupted, and upon this FiS- 199.- Double-horned Khinoceros.

they introduced many
ingenious alterations, not one of which was true. — R. K.]

Fig. 200.— Klip-das.

[The Cape Dassar, or
hyrax. Cuvier had the
merit of transferring
this curious little animal
(not larger than a rab-
bit) from the erroneous
position in which all
preceding zoologists had
placed it, to the order
pachydermata. — R. K.]

The mode of forma-
tion of the horns called antlers is as follows : — At a cer-

Fig. 201.— The Cape Dassar, or Hyrax,

242 ZOOLOGY.

tain age there appears a growth of bone on the frontal bone,
resembling what medical men call an exostosis, or .the
callus of fractured bones. These protuberances, which are
very compact, grow rapidly, and carry the integuments
with them ; they are also very vascular. After a time, a
series of osseous tubercles begin to form around the base
of the osseous horn, which increasing, obliterates the blood-
vessels, thus cutting off the supply of blood to the integu-
ments covering the antlers. The integuments drop off con-
sequently, and disappear, leaving the antler itself exposed.
And now the antler itself dies, as it were necrosed, and ends
by being detached from the cranium. In twenty-four hours
after this, a thin pellicle covers the surface from which the
antler had been detached, and soon a new prolongation begins
to grow in the place of the one which has been shed. Gene-
rally, the new antler is greater than that to which it succeeds,
and its branches are larger and more numerous ; but it is of
no longer duration than the first, and it undergoes the same
changes.

With one exception, the reindeer antlers grow only in

Fig. 202.— Head of the Goat. Fig. 20^— Head of the Elan, or

'Northern Elk.*

the male. The phenomenon has obvious S37mpathies with
the organs of reproduction, for they persist for more than
a year in those animals in which the rut does not corne to
a crisis and is limited. It is periodic, and occurs in the
spring.

§ 394. The extension of the nose in the elephant into a

* This must not be confounded with the Eland of South Africa, which is
an antelope.

OF THE. CLASS MAMMALIA.

243

flexible' and ^ dexterous proboscis is a modification of the organ
well deserving notice. The proboscis of the elephant is, in
fact, an extension of .the nostrils, forming a double tube, and
fitted to perform the office of a hand and a nose. By it water
and food are conveyed to the mouth, and air to the lungs ;
a fibro-tendinous membrane lines it throughout, and to this
and to the forehead and integuments are attached thousands
of small muscles [or as some view the structure, of two layers of

Fig. 204. -Elephant of Indii
K 2

244

ZOOLOGY.

muscles only — R. K.], so arranged as to elongate and shorten
the instrument in every conceivable manner. A cartilaginous
and elastic valvule exists superiorly, so as to cut off, at the will

Fig. 205.— Section of the proboscis of the Elephant.

Fig. 206.— Molars of the Elephant :— A, Asiatic; B, African.

of the animal, all communication between the proboscis and the
true nostrils superiorly; a finger-like appendage terminates
this remarkable instrument inferiorly. The enormous weight
of the head renders a proboscis necessary to the existence of
the animal, without which it could neither feed nor drink.

The elephants are the only animals which have a proboscis,
but there are others in which the nasal organs are prolonged

OF THE CLASS MAMMALIA.

245

into something analogous. Such are the tapirs (Fig. 208).
The desmans (Fig. 209), small insectivorous animals, allied to
the musaraignes, shrew mice, but adapted for swimming
with ease, and searching for their food at the bottom of
burrows dug in beaches, present a similar elongation of the
nostrils.

Fig. 207.— South African Elephant.

[South African Elephant, characterized by the great size of its
ears and by the configuration of the trituratory surface of the
molar teeth (Fig. 206). There are some grounds for suspicion
that the elephants of Central and Northern Africa differ specifically
from those of South Africa. — R. K.]

Fig. 208.— Head of the Tapir

Fig. 209.— The Desman.*

§ 395. The Trunk. — The vertebral column presents but
slight modifications in the vertebrata, and these are chiefly
confined to a difference in the number of the vertebrae.

* Musk Shrew, Sorex Moschatus, also called My ogale. The Desman of the
Pyrenees is the type. There is a Russian or Muscovite species — the Russian
Musk Rat.

246 ZOOLOGY.

Again, this difference is chiefly remarkable in the caudal or
coccygeal part of the column ; in some, as in bats of the
genus Pteropus, there exist no coccygeal vertebrae whatever ;
in other mammals, they number forty, fifty, and even sixty;
and in these we also find this distinction, — that the vertebral
canal for lodging the spinal marrow and a portion of its
nerves still exists in some of these bones, whilst in the ter-
minating ones it is wholly absent. In most mammals the
caudal part of the column is but little used for locomotion :
in the kangaroo, jerboa, &c., it becomes, with the hinder
limbs, a sort of tripod, from which the animal springs with
great force (Fig. 103) ; many American apes use the tail as
a prehensile organ of great power, as a fifth hand in fact, by
which they dexterously cling to branches of trees (Fig. 110) ;
finally, in the cetacea (whales) it becomes enormous, and
serves as their great moving agent in swimming. It is
beneath the bodies of these caudal vertebrse that we find the
bones shaped like the letter V, which seem to serve as ribs to
strengthen the flexor muscles of the tail (Fig. 210). The
length of the neck varies also in mammals, although the

Fig. 210. — Skeleton of a Cetaceous Animal (the Dugong).*

number of cervical vertebraa is, with few exceptions, the same
in all. The exceptions are the ai, which has nine, and the
lamantin, which has six. The giraffe and whale, opposed as
they are in respect of length of neck, have precisely the same
number of cervical vertebrse.

§ 396. The conformation of the thorax or chest varies
little ; the number of ribs is generally from twelve to fourteen

* I regret that my friend has placed this figure here, for, in point of fact,
the Dugong is not a cetaceous animal, as I proved long ago. See Trans.
R. S. of Edin. for 1830.— R. K.

OF THE CLASS MAMMALIA.

247

pairs ; in the horse, however, there are eighteen, and in the
elephant, twenty pairs. The sternum, which in general is
flat and smooth, is raised into a crest in the bats, as if to
accommodate the greatly increased depressor muscles of the
wings, thus adapting the animal for flight, an arrangement
we find carried to its highest extent in "birds. In all this
class (class mammals) a muscular diaphragm separates the
cavity of the chest from the abdomen.

§ 397. Limbs. — In all mammals, with the exception of
the cetacea, there are four limbs ; two thoracic, and two abdo-
minal or pelvic. In the cetacea there are only two, the
thoracic. They are uniformly composed of a basilar portion or
base, followed by three principal segments or portions respec-
tively, thus : the arm and thigh, the fore-arm and leg, the
hand and foot. The basilar portion of the anterior or pectoral
extremity is the shoulder blade, or bone called scapula, whose
form varies much according to the character of the movements
of the animal. In animals which use their pectoral extremi-
ties as instruments of prehension as well as support, the
scapulae are secured in their place by two bones which rest on
the sternum ; these are the collar bones (Fig. 81) ; but in
such animals as the horse, using its anterior limbs wholly for

Fig. 211.

Fig. 212.

progression and not prehension, the collar bones are either
altogether wanting or reduced to mere vestiges. Some very
singular and anomalous animals, also mammals, no doubt,

248 ZOOLOGY.

differ widely in many respects from the ordinary organiza-
tion, and in none more than what concerns the structure of
the shoulder ; we allude to the ornithorhynchus paradoxus
and echidna setosa, of New Holland. In these the skeleton
of the shoulder more resembles what we find in lizards and
in birds than in mammals.*

Fig. 213.— The Roe, or Roebuck ; .Chevreuil.

The function of the basilar portion of the skeleton of the
abdominal or hinder limbs varies less thau does that of the
pectoral. In the cetacea, also in the dugbng and lamantin,
the pelvis is reduced to a mere fragment; in other mammals,

* The arrangement of the bones of the shoulder in these singular animals
will be best understood by a reference to Fig. 211, in which d points to two
bones on each side (of which one is not represented here) corresponding to
the usual collar bones of mammals; a points to the scapula ; h to the cavity
for the articulation of the head of the humerus; o the prolongation of the
scapula to the sternum, analogous to the coracoid clavicle of birds ; co an
osseous piece, the analogue of which has not been determined ; s and c point
to the ribs. The meaning of this complexity of the shoulder in this class of
animals has never yet been explained. — R. K.

OF THE CLASS MAMMALIA.

249

the bones of the haunches (i) articulate in an immovable
manner with the sacrum (sa), and reuniting inferiorly, form
a girdle or pelvis, thus surrounding the lower portion of the
trunk. The form and dimensions of this girdle vary much,

Fig. 214.— The Mole.

and ccs fen's paribus, the erect position on the lower limb is
easier as the pelvis is larger. It must also be remarked, that
in the opossums and other marsupial animals, the muscles of
the abdomen assisting in the formation of the pouch of these
animals, are attached to two peculiar bones articulated to the
anterior parts of the pelvis, and called by anatomists the
marsupial bones* (Fig. 212 m).

Humerus of the
Mole.

Anterior Limb and Hand of the Mole.
Fig. 215.

In the arm and thigh in all mammals there is but one
bone, the humerus and the femur; in the fore-arm and leg,
two bones — the radius and ulna in the fore-arm, the tibia and
perone or fibula in the leg. In bats there is a rotula in the

* These bones are present whether the pouch be there or not. — R. K.

250 ZOOLOGY.

arm as well as in the leg. Generally, these leg and arm bones
are short and strong, or long and slender, according to the
habits of the animal. The mole and chamois may serve as
the examples of this modification : strength characterizes the
actions of the mole, and swiftness those of the chamois.
When the hand no longer serves for prehension, but merely
for support, the radius loses its power of rotation on the ulna,
and ends by uniting with it so intimately as to be no longer
distinguished from it. In the solidungulous animals, the same
happens with the fibula and tibia.

The foot and hand vary in mammals according as they are
used for prehension, swimming, flight, or walking on ground
more or less firm. These circumstances have been already
alluded to. The fingers or toes are never more than five, and
their number diminishes according as the extremity is more
exclusively used for simple progression.

§ 398. Organs of the Senses. — The perfection of the
fingers and toes as instruments of touch seems to depend on
the fineness of the integuments, the form of the nail, and the
flexibility of the instrument. In this respect man stands pre-
eminent, in accordance, no doubt, with his higher intelligence
(Fig. 98).

§ 399. The organs of the other senses are also analogous
in all the mammals to those of man. In those remarkable for
the fineness of their powers of smell, — the dog:, for example,
— the nasal fossse and frontal sinuses are much enlarged, and
the turbinated bones of the nostrils are greatly developed,
thus extending the surface of the pituitary membrane, on
which the nerves of smell are distributed.

§ 400. In nocturnal animals, the eyes are generally larger
than in the diurnal ; and in the former the pupil of the eye,
when contracting, assumes the form of a fissure, losing its
circular character. In moles, whose residence is underground,
the eyes become extremely small, and seem in some to be
mere vestiges or rudimentary organs ; in the aquatic mam-
mals, the lens is, for an obvious reason, spherical. In many
mammals there exists a coloured part of the choroid tunic of the
eye called tapetum, the uses of which are unknown.* Many
have a third eyelid placed vertically at the inner angle of the
horizontal eyelids. Finally, the direction of the eyes varies
much : in man they are directed forwards ; but, as we descend

* The glaring of the eyes in the dark depends on the presence of this
tapetum; its colour varies in different animals. — R. K.

OF THE CLASS MAMMALIA. 251

in the scale, the direction becomes more and more lateral,
and the animal can no longer see directly before him : the
sphere of vision for each eye must therefore be distinct.

§ 401. The organs of hearing offer some modifications in
relation to the habits of the animal. In aquatic mammals
the external ear is small, or rudimentary, or absent ; in the
herbivora it assumes the form of an ear-trumpet, becoming
more and more detached from the head, and fitted thereby to
perform the functions of an acoustic tube. In the nocturnal,
the membrana tympani occupies more space, and is nearer
the surface.

§ 402. Nervous System. — As regards the nervous system,
in mammals it differs only in respect of the more or less
development of its various parts. In all, the encephalic part
is very considerable, whether viewed proportionally as regards
the nerves or the bulk of the body of the animal; but all the
organs composing it do not contribute to this development :
thus the cerebral hemispheres are very large, whilst the
optic thalami may be very small, or even rudimentary ; the
reverse of what happens in birds, reptiles, and fishes. The
cerebellum is also generally large in mammals, and is com-
posed of a median portion (processus vermiformis superior))
of two hemispheres, and of a commissure, surrounding the me-
dulla spinalis superiorly, the annular protuberance. More-
over, many differences exist among mammals in respect of
these organs, as well as regards the depressions and circum-
volutions on the surface of the brain. As we descend from
man to apes, from these to the carnivora, and from the car-
nivora to rodents, the brain generally becomes smaller and
smaller, and smoother. The face also is developed in an
inverse ratio to that of the brain, and the measure of the
intellectual faculties may be guessed at by observing this
increasing size of the face as compared with the brain.

In the marsupialia and monotremes, the brain seems still
further degraded by the absence of, or at least the rudimen-
tary state of, the corpus callosum, which in all other mam-
mals unites the hemispheres of the brain to each other.

§ 403. Functions of Nutrition.— The functions of nutri-
tion resemble each other throughout nearly the whole of the
class ; the digestive tube is the organ which shows the most
remarkable variety in its arrangements.

Nearly all have teeth (§ 53), which vary in number and
form, in accordance with the kind of food they live on. But

252

ZOOLCGY.

they may be replaced by whalebone, as in certain of the
cetacea (Figs. 15 and 16), or by a horny bill, as in the orni-
thorhynchus paradoxus ; hence the name.

Gullet.

(Esophageal
Groove.

Maniplus.

"Duodenum.

Pylorus. The Kennet. 2nd Stomach. Paunch.
Fig. 216.— Stomach of the Sheep.

§ 404. The stomach is usually simple, as in man (Fig. 24)
and'the ape (Fig. 5) ; but in others, as in ruminants, the organ
is subdivided into a number of compartments, from the first

Gullet. - —
(Esophageal Groove.

Maniplus, or Third
Stomach.

Rennet, or Fourth
Stomach.

Duodenum.

Pylorus. Second Stomach. Paunch.

Fig. 217.— Interior of Stomach of the Sheep.

of which the food, after remaining a certain time there, re-
turns to the mouth by the gullet, to be remasticated (rumi-

OF THE CLASS MAMMALIA.

253

nation), and thence transmitted into the following compart-
ments, without again passing into the first.

These stomachs, or stomachal compartments, in ruminants
are four in number. The first, which is the largest, is called
the paunch (Fig. 216) ; its surface is furnished with papillae
and an epidermic covering (Fig. 217) ; it fills a large part of
the left side of the abdominal cavity. The second stomach,
called the king's hood, is small, and looks like an appendage
of the paunch. But it differs internally (Fig. 217), being
composed of a number of folds disposed so as to form polygonal
cells or cellules, like honeycomb. The third stomach, not so
small as the second, is called maniplus, from the number of
longitudinal folds seen in its interior : finally, the fourth is
called the rennet : its property of curdling milk renders it
remarkable. The first, second, and third stomachs commu-
nicate directly with the gullet, which indeed seems to open
equally into the first and second. After being ruminated,
the food descends from the gullet into the third stomach by
means of a semi-canal, which no doubt becomes complete at
the time, thus directing the food in one course only, diverting
it from the paunch and second stomach; from the maniplus,
it passes into the rennet or fourth stomach, in which cavity
digestion is finally completed.

The act by which the food passes when first swallowed
into the paunch and thence to the second stomach, but which
on being ruminated or remasticated descends only to the
third by means of the cesophageal canal, is not an act of intel-
ligence, but one purely instinctive, and perhaps even mecha-
nical, due to the anatomical disposition of the structures.
Food of the size it is when first swallowed, opens mechanically
the semi-canal, by which the gullet communicates with the first
and second stomachs; but fluids and the remasticated food being
much finer, do not effect this, and thus pass on by the canal
into the maniplus or third stomach. Rumination is generally
ascribed to the second stomach, but it appears more probably
due to a combined action of the first and second, which, by
contracting, forces the bolus again into the gullet, by whicn
it remounts to the mouth.

The paunch is of very great size in the adult animal;
in the young, whilst living on the milk of the mother,
it is smaller than the rennet, thus showing (?) the in-
fluence the food exercises in enlarging the capacity of the
organ.

254 ZOOLOGY.

§ 405. The capacity and length of the intestines are much
less in the carnivora than in the herhivora, being in many of
the former only three or four times the length of the body ;
whilst in the sheep, for example, it is nearly eight times that
length. Generally it terminates by a distinct opening ; in
the ornithorhynchus, however, the anus opens into a cloaca,
or cavity, in which terminate also the urinary organs, resem-
bling birds in this respect. The salivary glands, the liver,
pancreas, peritoneum, and its appendages, resemble the same
organs in man.

§ 406. The more essential differences exist in the apparatus
of respiration and circulation; the heart has always two auricles
and two ventricles (§ 92, Figs. 39, 40) ; the lunajs are always
composed of cellules, which do not allow the air to escape into
the other organs of the body, as in birds. The blood is rich
in organized matters, and the form of the globules circular
(§ 81, Fig. 36).

§ 407. We have already shown that the mammals differ
widely from each other in respect of intelligence (§ 337) ;
and the various instincts bestowed on them by nature to
supply the deficiency of a higher intelligence have been
already alluded to. It is the class which most interests man,
including within it, as it does, so many of our domestic ani-
mals ; the horse, ox, sheep, &c. So complete, indeed, have
been the effects of domesticity over some of these races of
animals, that the primitive race seems altogether to have
disappeared. The moral as well as the physical characters of
the domesticated races are thus affected and altered. The
dog, for example, so varied by domestication, may yet have
sprung from a single race, neither a wolf nor a jackal, but a
dog analogous to the common shepherd's dog, or wolf-dog, as
it is sometimes called.

The power by which this complete sutfjugation of a race of
animals is effected seems to be the inspiring them with con-
fidence by kind acts and uniformly good treatment. We
must show them that the supply of food depends on us ; and
if to that we add food of a choice character, artificial wants
are thus created, which the animal feels man alone can
gratify. Hence his attachment to him ;* finall}r, some are
extremely fond of being noticed and made much of.

Confidence and dependence on man being once established,

* It is chiefly by means of sugar and other delicacies that horses and deer
are fanght those extraordinary tricks exhibited in the circus.

OF THE CLASS MAMMALIA. 255

fear may afterwards be superadded ; but this must be done
with great caution, lest it excite terror and disgust.

But all mammals do not thus readily lay aside their savage
disposition, being either less confiding or less sensible to acts
of kindness, or it may be that their intellect is lower ; but
be this as it may, it is evident that any animal, to become
completely domesticated, must be disposed to it by the instinct
of sociability. No solitary mammal ever becomes completely
domesticated, however readily he may be tamed.* Sociability
is an essential of complete domesticity, man becoming, as it
were, the head of the troupe. A disposition to domesticity
may be considered as the extreme development of the instinct
of sociability, f

§ 408. Let us now consider the moral and physical influ-
ences which domesticity exercises over the domestic races of
animals ; how, in fact, it produces new varieties.

The physiological law of hereditary resemblances holds
true in all animals, man included ; the young resemble their
parents in conformation, physical and mental qualities, and
even in respect of disease itself. But all the individuals of a
race do not possess in the same degree the same qualities,
moral and physical; and hence arises the possibility of giving
to certain qualities a higher and more constant development.
Within certain limits, then, man may modify races, by regu-
lating the succession of generations, selecting a type or
standard for the new variety he is desirous of creating. J By
endeavouring thus to develop from generation to generation
a certain physical or mental quality, we render such qualities
hereditary, at least for a time.

* The cat may seem an exception to this view, but, in fact, the cat is never
completely domesticated.

t The theory of domestication is one of extreme difficulty. — E. K.

j The bloodhounds transplanted into America by the Spaniards, employed
at first to pursue only men and deer, furnish a remarkable instance of the
power of transmitting certain newly-created mental quali ties, hereditarily.
In different parts of America, as on the central table-land of Santa-Fe, these
animals have preserved their original instincts and physical qualities, but
amongst the poor inhabitants of the banks of the Magdalena they have become
degraded, partly by a mixture with other dogs, partly by a scarcity of food,
and in this degenerate race of the bloodhound a new instinct has been
developed. The chase in which they have been long emj loyed is that of the
white-muzzled Peccari. The skill of the dog consists in moderating its
courage or ardour, so as not to attack any individual of the troop or herd of
peccaris, but to keep the whole in check. IS'ow it has been observed that
these dogs act thus on the very first occasion they hunt the peccari, whereas
any strange dog throws himself on them at once, and is devoured in an
instant, whatever be its strength.

256 ZOOLOGY.

Even in our own times, guided by interest, men have thus
formed new varieties of sheep, oxen, and horses. To Bake-
well, for example, we owe the variety of sheep called New
Leicester, remarkable for their fattening qualities. The fore-
quarters of the large Wurtemburg variety of sheep, as a
valuable sort for the market butcher, weigh from 52 to 55
per 100 of the whole weight ; in the New Leicester or Dishley
breed, the weight amounts to 70 or even 75. It must be
known to all how the quality of the wool is improved by
crossing with the merinos of Spain.*

Finally, the various breeds of horses prove these facts
respecting the influence of man over the domestic races of
animals. Our agricultural breeds of horses owe in part their
stature, their forms, and qualities to the race from which
they have sprung : but the circumstances in which they are
placed when young exert an influence over them no less great.
The young resembles the mother more than the father in
respect of the size and height ; whilst it resembles the father
more as regards the feet, speed, courage, (fec-
it is essential therefore, in breeding, to select those indi-
viduals only which possess the requisite qualities, rejecting
their opposites ; or, in other words, to breed from those having
opposite qualities : in time the new forms become hereditary
and general. To attention to these matters the Arab horses
owe their grand qualities. The noble breed they call kochlani
has its purity secured by authentic legal attestations, during
a series of four ages, and the known genealogy of several
of these fine animals extends to two thousand years. The
English race-horse owes its qualities to a mixture of the Arab
stallion with the indigenous mares of England; hence its
stature and astonishing rapidity. The abundance and quality
of the food, the nature of the climate, the daily cares bestowed
on the horse, influence the race much more than is generally
supposed : as a proof of this, we may notice the rapidity with
which the finest English horses degenerate in certain locali-
ties, as in the studs of Kopschan on the borders of Moravia.
But the same fact may be observed nearer home. If two
colts of the same breed, of Lorraine for example, be placed,
one in Flanders the other in Normandy, instead of retaining

* It was in 1776 that the superintendent of finances, Daniel Trudiane,
attempted first the introduction of the merino into France, aiid it is to
Daubenton, the collaborates of Buffon, that is due the success of the enter-
prise.

OF THE .CLASS MAMMALIA. 257

their resemblance to each other, they will at five years resem-
ble horses of different breeds : the one will grow up a coach-
horse, light and elegant ; the other an enormous animal,
hardly able to trot, but equal to the draught of the heaviest
loads. Where nourishment abounds, there the size and
weight of the horse increase ; opposite circumstances are
attended with other results. Fed on strong humid pastures,
the horse becomes heavy, and his form and hair coarse ; on
light soils, and especially if grain be added to his ordinary
food, his form becomes light and elegant : finally, the careful
grooming bestowed on the English horse contributes to
improve his form, and especially the fineness of his limbs.
Thus it happens, as in the dog, that varieties may be so
multiplied as to make it appear that they must have sprung
from more than one species : nevertheless, all these modifica-
tions have their limits, beyond which nature will not or
cannot go : they never destroy the distinctive characters of
zoological species.*

§ 409. Classification of the Mammalia. — There exist,
as we have seen, considerable differences amongst the mam-
malia, and these modifications of structure serve as the basis
for the division of the class into groups of an inferior rank,
called orders. Most of these groups are so distinct as to
admit of no doubt in respect of their limits : they constitute,
in fact, natural divisions ; but in others the line of demarca-
tion is by no means so distinct. Thus a mammal may have
points of resemblance so close to two groups as to render it
almost indifferent to which it be referred. To some natu-
ralists, differences appear important which are disregarded by
others, and hence a want of agreement on the subject of
classification has always prevailed.

The method followed here is nearly that proposed by
Cuvier. It rests mainly on the differences mammals show
in respect of their extremities and teeth, differences which
always imply a crowd of others in structure, habits, and
even intelligence.

§ 410. Keeping in view the ensemble of these characters,
the class mammalia may be divided into two groups, — the
monodelphic and didelphic.

The monodelphic or monodelphian are the more numerous,

* Experiments made in this country have led to entirely different results.
The various breeds of horses, cattle, and sheep remain unaltered, on what-
ever pastures they may be fed. — R. K.

S

258 ZOOLOGY.

and are distinguished chiefly by their mode of development.
At birth they are already provided with all their organs, and
before birth they derive their nourishment from the mother
by means of a placenta. Their brain is more perfect than

Fig. 218. — Caucasian Kace.

the didelphian, by the presence of a corpus callosum uniting
the two cerebral hemispheres (§ 186). Finally, the walls of
the abdomen have no osseous supports attached to the margins
of the pelvis, as we find in the second great class of mam-
mals. The mammals thus organized have been subdivided
into two groups,— namely, ordinary mamjnals and pisciform
mammals.

§ 411. The ordinary mammals are organized principally
to live on solid ground ; the skin is provided with hairs.
These animals are further subdivided into ten orders : the
bimana, quadrumana, cheiroptera, insectivora, rodentia, eden-
tata, carnivora, amphibia, pachydermata, and ruminaritia.
The first eight of these orders have flexible fingers and toes,
with nails covering only the dorsal aspect of the toe or finger,
and comparatively small; hence they have been called ungui-
culata ; the last two, — namely, the pachydermata and rumi-

OF THE CLASS MAMMALIA.

259

nantia, have the extremity of the finger and toe entirely
enclosed in a hoof; they are thus called ungulata.

§ 412. The order bimana includes only man : in him alone
the arms are destined for prehension, the limbs for progression
and support in the erect attitude. Thus, the natural position
on the soil is unmistakeably vertical. The teeth are of three
kinds (§ 52), and have their edges on the same plane ; they
are frugivorous : finally, the brain is more perfect, more
highly developed, than in any other animal.

Though man represents but a single species, yet in his
varieties he offers many remarkable differences, especially as
to colour, features, and proportions ; of these varieties, the
more remarkable are the white or Caucasian, the yellow or
Mongolian, the black or Ethiopian.

Fig. 219.— Mongol Kace.

The Caucasian variety of man occupies all Europe and
Western Asia as far as the Ganges, likewise Northern Africa.
To it belong the more highly civilized nations. The region of
the Caucasus has been supposed to have been the cradle of the
race, hence its name. A fair skin, elevated forehead, small
s 2

260

ZOOLOGY.

cheek-bones, hair varying in colour, but always smooth, to-
gether with high intellectual qualities, characterize the race.
The Mongolian variety differs in many respects from the

Fig. 220.— The Young Memnon, representing the Coptic Eace (from the
celebrated bust in the British Museum); copied from my work on the
Races of Men.— R. K.

OF THE CLASS MAMMALIA.

261

Caucasian. The brow is low and square, the eyes small and
oblique : cheek-bones prominent, nose flat, little or no beard,
hair black and smooth, colour yellow. Their language is
monosyllabic. Their original country is Central Asia, ex-

Fig. 221.— Mongol (From
Clark's Travels.)

Fig. 222. — Bosjesman, or Yellow
African Kace.

Fig. 223.— Bosjesman playing on the Gourah (from BurchelFs South Africa).

262

ZOOLOGY.

tending to and including China and the Chinese, the earliest,
seemingly, of civilized men. Siberia and Mongolia, the
Crimea, Thibet, Japan, the Aleoutian Isles, and even the
western shores of Northern America, are all occupied by this
race of men.

Fig. 224. — The Aboriginal Dative of Australia, from Peron.

Some naturalists view the Malays as a distinct race of
men ; but most view them as a mixture of two races.
Lastly, the degraded races known as Laps, Samoides, Es-
quimaux &c., seem to be related to the Mongol race. A third
distinct variety of mankind is the Ethiopic, confined to
Africa, south of Mount Atlas, seemingly composed of several

OF THE CLASS MAMMALIA.

263

distinct races of men, such as the Negro, Bosjesman, Hot-
tentot, Mozambique, &c. It is characterized by the dark
colour of the skin, frizzly hair, low and compressed forehead,
projecting jaws, large lips, and muzzle-shaped mouth, with

Fig. 225.— The Skull of the Tasmanian.

Fig. 226.— Negro Cranium.

other peculiarities, which need not be mentioned here. The
primitive population of Australia and of the numerous isles
of the oceanic Archipelago, have been viewed by some natu-

264

ZOOLOGY.

ralists as constituting a distinct variety ; the Alfourons are
but little known.

Finally, the indigenous inhabitants of America have been
viewed by many naturalists as a distinct race of men. They
are copper coloured, have long, black, straight hair, and but

Fig. 227.— Caffre Skull.

Fig. 228.— The Cherokee Head.

little beard. But some of them have strong analogies with
the Mongolian race of Asia, whilst ;others approach somewhat
the form of Europeans. The nose is as prominent as in the
European, and their eyes are large and open.

OF THE CLASS MAMMALIA. 265

[The cranium of the American race is remarkable for the
depression of the forehead, and this character seems to have
belonged to the aboriginal races first peopling America. This is
proved by the remains of Mexican antiquities and by the drawings
of the Aztec race, a race now seemingly extinct. To such an ex-
tent was the forehead depressed in that race, that were it not for
these drawings and the existence of the same malformation in the
Cherooks and other tribes still existing, it might have been
inferred that no such race of men could ever have existed.

Hippocrates mentions a race of men with similarly formed heads
as inhabiting, in his days, the shores of the Euxine, and recently
crania of a similar character have been said to have been found
in Gennany, in situations implying a high antiquity. A notion
has been thrown out by some popular writers that man, at first
rude and savage, small brained, and deficient consequently in
intellectual powers, has been gradually improved by education
and civilization, and that by the culture of his intellectual powers

Fig. 229.— Ethiopian Kace.

his brain has become enlarged, and with it the cranium. Like all
medical theorists (for they are medical men who advocate such
hypotheses) they catch at any statement which may seem favour-
able to their latest hypothesis, wholly regardless not only of its
incompatibility with other facts but with their own theories. Such
a notion is moreover refuted by all human history, and is abso-
lutely antagonistic with the chronological system which to a man
they have adopted. — R.K.]

["The term Caucasian was devised by Blumenbach to charac-
terize a certain number of the higher races of man, but he did

266 ZOOLOGY.

not attach any theory to it ; that has been done by later writers.
His arrangement of the races of men was geographical ; and
although it has certain facts favourable to it, the view is now
very generally abandoned.

"Each race seems to have a civilization peculiar to itself;
thus the ancient Greek, seemingly now extinct, carried the arts,
literature, and even science, or at least philosophy, to a point
they have never reached since their epoch ; the Coptic race had
its own form of civilization, as exhibited in their architecture,
sculpture, and painting ; the same may be said of the Persian
and Mongol. The Western European races are chiefly deficient
in imagination and genius. The Negro race has never invented
anything.

" Of all the races of man, the most remarkable is the Saabs, or
yellow race of Africa : it includes the Hottentot and Bosjesman,
properly so called ; but travellers affirm that the Australian or
Tasmanian stands lowest in the scale of humanity. However
this may be, certain it is that most of the coloured races of man
become rapidly extinct in presence of the white or European
races ; and were it not for climate, it is probable that many of
the races of man would have been long ago extinct, or nearly
so ; but nature seems to oppose the transfer of a race from the
continent on which it first appeared to another. Thus the
English make no progress in reality in India, and from northern
Africa all the immigrant races of Phoenician, Greek, Roman,
Vandal, &c., have disappeared. The Spanish blood will ere
long become extinct in America.

"The anatomical structure of the races of man differs con-
siderably, so that there is not the slightest difficulty in distin-
guishing their various crania, although popular writers are fond
of denying this fact ; they are misled by the affiliations which
naturally exist amongst the races of man as amongst all other
animals ; these affiliations show that the races of man now on
the globe form one family." — ft. K., Races of Men.']

§ 413. The order of the quadrumana is" composed of those
animals which have the great toe so constructed as to perform
the functions of a thumb, and which use the four limbs as
well for prehension as for locomotion. Like the bimana, they
are frugivorous, and their teeth are similar to ours. In this
group are arranged the apes (Fig. 110, 133), the ouistiti
(Fig. 6), and the makis (Fig. 230).

The apes are animals of small or moderate stature, the
muzzle moderately prominent, the neck short, the body
slender, and the extremities thin and long. They are covered
with long and silky hair, closely set; nevertheless, their re-

OF THE CLASS' MAMMALIA.

267

semblance to man is sometimes extreme, and there are some
which, when young, have the facial line not more oblique
than in the negro ; but with age, in some the face projects,
becoming a muzzle, resembling that of the dog (Pig. 231).
The gestures and tricks of these animals have often a strong

Fig. 230. — White-fronted Mains or Lemur, with its Young.

resemblance to our own. With the aid of a stick some hold
themselves upright, and even walk as we do, but nev-er steady
nor assured in their step, so that in the vertical position they
always seem constrained and ill at ease. On the other hand,
in the forest they display the utmost agility, and this seems
indeed to be their natural locality. To arms of great length,

268 ZOOLOGY.

and feet; organized as hands, with an opposing thumb, in some
we find in addition along prehensile tail, so that their activity
amongst trees becomes almost incredible.

Apes inhabit only warm countries ; a single species* dwells
on the rock of Gibraltar ; the apes of the New World are all
distinct from those of the Old.

Fig. 231.— Dog-faced Baboon.

§ 414. The order of carnivora is composed of ordinary
unguiculated mammals ; the form of their dentition is com-
plete, but they have no opposing thumb. According to the
mode of life of these animals, their intestinal canal is short ;
their jaws and their muscles strong, in order to seize and
devour their prey ; their head from this circumstance seems
large. The jaws are short, thus favouring their strength,
and the form of the temporo-maxillary articulation proves
that the teeth are made for tearing and cutting, but not for
grinding or masticating. The canine teeth are large, long,
and very powerful ; the incisives, six in number in each jaw,
small ; the molar, sometimes entirely adapted for cutting, in
others surmounted with rounded tubercles, presenting no
conical points, arranged as in the insectivora. One of these
molar teeth is usually much longer and more cutting than
the others, and has therefore been called the carnivorous
molar tooth ; behind these (on each side) are one or two
molars, almost flat, and between the carnivorous molar and
the canine a variable number of false molars. The food of
the animal, whether exclusively carnivorous or mixed with

* [Now (1863) reduced to three individuals. -C. C. B.]

OF THE CLASS MAMMALIA.

269

other matters, may be judged of by the varying proportions
of these cutting or tuberculated parts of the molar teeth>

Animals of this order have generally the toes armed with
claws adapted to hold and to tear their prey ; usually also
they have no collar bones. This kind of organization is met
with in the genera cat, hysena, viverra, martin, otter, dog,
badger, bear, &c.

The genus cat (Fig. 232), which may be viewed as the
type of the carnivora, comprises not only the common cat, but
also the tiger, lion, panther, lynx, &c. ; their jays are short,
and are acted on by muscles of extraordinary strength ; their
retractile nails, concealed between the toes in a state of repose

Fig. 232.— The Panther.

by means of elastic ligaments, are never blunted. Their toes
are five in number on the anterior limbs, and four on those
behind. Their hearing is exceedingly fine, and the best deve-
loped of all their senses. They see well by day and night,
but they are not farsighted ; in some the pupil is elongated
vertically, in others it is round. They make great use of the
organ of smell; they consult it before eating, and often when
anything disturbs them. Their tongue is covered with horny
and very rough points. Their coat is in general soft and fine,

270 ZOOLOGY.

and the surface of the body very sensible to the touch ; their
moustaches especially seem to be instruments of great sensi-
bility. Though of prodigious vigour, they generally do not
attack animals openly, but emploj1" cunning arid artifice.
They never push their prey to flight, but watching by the
margins of rivers and pools in covert, they spring at once on
their victim.

At the head of this genus stands the lion, measuring fre-
quently twelve feet in length, or over six feet to the setting
on of the tail; about three feet in height, and characterized
by the square head, the tuft of hair terminating the tail, and
in the male by the main which flows from the head and neck.
The lion is the most powerful of the carnivora ; with a single
blow of his fore paw he can break the back of a horse, and a
stroke of the tail will strike down the strongest man. For-
merly spread over the three great divisions of the Old World,
he seems now limited to Africa and Asia.

The animal which some call the American lion belongs to
a different species ; it is called couguar, and is peculiar to the
New World.

The royal or Eastern tiger is an animal more dangerous
than the lion, which it nearly equals in strength, but exceeds
in ferocity. The hair in the tiger is short and smooth, and
yellowish above, with black transverse bands or stripes ; it
inhabits India, where it does much damage.

The jaguar, not much less than the Eastern tiger, and
almost as dangerous, is a native of America, and is found only
there. It inhabits the great forests. Furriers call it the
great panther, for it is spotted like that animal ; the fur being
yellow, with four rows of dark spots like eyes ranged along
the flanks, with white and black stripes beneath.

The panther (Fig. 232), so remarkable for the beauty of its
fur, is found all over Africa and Asia^ together with the
leopard, which it much resembles; the I'ur is yellow, with
numerous dark spots.

The lynx, also, or cat, is distinguished by a pencil or tuft of
hairs surmounting the external ears ; the coat or fur is red
coloured, spotted with a reddish brown. It is indigenous to
temperate Europe, but it has nearly disappeared from popu-
lous countries ; it is still found amongst the Pyrenean moun-
tains, in the kingdom of Naples, and in Africa. It ascends
trees ; and, having excellent sight, does much mischief by
destroying hares and deer. The ancients ascribed to it a

OF THE CLASS MAMMALIA.

271

power of vision equal to the seeing through a stone wall —
hence the phrase, lynx-eyed.

The common cat comes originally from the forest. In a
wild state it is of a brown colour, somewhat greyish, with
deeper coloured transverse waves. The tail is annulated with
dark rings; the inner side of the thighs and feet, yellowish.

The hyaena is distinguished from the genus cat by the
number of toes, which is four for all the limbs, as well as by
the enormous strength of the teeth and jaws, and by the
claws or nails, which are not retractile during walking. The
tail is short and pendant, and underneath the anus is a pouch
which secretes a disagree-
ably-smelling viscous mat-
ter. Their gait is odd,
and they carry their hind
quarters much lower than
the fore. They are noc-
turnal animals, preying
on whatever they can ven-
ture to attack ; cowardly ;
they disinter the dead, and
despise no kind of food.
They resort to caverns du-
ring the day-time. Their
reputation lor ferocity is

not oorne out by the fact. The common hyaena belonged
originally to Asiatic Turkey, Syria, and to some countries
of Africa.

The carnivora called putorius or polecat, mustela or common

Fig. 233.— The Spotted Hyama.

Fig. 234.— The Weasel.

marten, otter or lutra, and some others, are remarkable for
the length of their bodies and shortness of their limbs. They
are all small, but extremely sanguinary.

272 ZOOLOGY.

The genus putorius comprises the common polecat, the
ferret, marten, the ermine, and several other species, which
all have the head rounded, the fur brilliant and soft, the tail
long, and anal glands which secrete a foetid matter.

The martens differ but little from the polecats, and are
equally sought after for their fur. The polecat, which does
such damage to the poultry, belongs to this genus.

The otter (lutra) has the head depressed and the feet pal mated.
Otters are aquatic nocturnal animals, inhabiting the margins
of rivers and lakes, and subsisting mostly on fishes.

The genus dog comprises the dog, properly so called, the
wolf, and the fox. All these animals are characterized by a
peculiar dentition, great strength and agility, senses of hearing
and smell acute, claws adapted for digging; they show a
partiality (some at least) for putrid flesh as food. Their sight
is excellent.

Fig. 235.— The Otter.

The domestic dog is distinguished from the other species by
the curved tail. This animal is born with the eyelids closed,
and they open only after ten or twelve days ; the female has six
or seven at a birth, and sometimes even^twelve. The dura-
tion of life is from twelve to fourteen years ; they have been
known, however, to live to twenty, and their age is determined
by their teeth, which in the young are white, pointed,
and cutting, but in the aged blunted, dark coloured, and
irregular.

The dog is the most complete conquest which man has
made in respect of any animal. The entire species has be-
come domesticated, so that the primitive condition is lost.
The wild dogs found in some countries are merely domestic
dogs which, being abandoned, have run wild, and recovered

OF THE CLASS MAMMALIA.

273

some of their primitive savage habits. Some naturalists
are disposed to think that originally there may have been
several species of the dog, and others imagine the wolf or
jackal to be the origin of the domestic dog ; but when aban-
doned on desert isles, the dog never assumes the character of
either of these animals. The dogs of people but little civilized
have the ears erect, and hence it has been supposed that the
shepherd's dog, or wolf dog, is the origin of the domestic dog
of all varieties.

The common wolf is readily distinguished from the dog by
the tail, which in the wolf is straight. The wolf has much
the air of the house dog (matin) ; but, unlike that animal, the
wolf leads a rather solitary life in the great forests, reuniting
in troops only when pressed with hunger. The wolf is agile,
adroit, strong, and well adapted for the pursuit, attack, and
conquest of his prey; nevertheless he is naturally slow and
cowardly, unless pressed by hunger ; he then attacks the
domestic animals under man's protection ; women and children,
and man himself, do not then escape his ferocity.

The Chacal, the Loup dore, inhabiting the warm coun-
tries of Asia and Africa, more resemble in its habits the
domestic dog than the wolf: it may be tamed.

Fig. 236.— The Fox.

The fox differs from the domestic dog by the form and

greater length of the tail, which is tufted ; by the vertical

form of the pupil during the day-time, and by the greater

comparative size of the head. They are nocturnal, dig bur-

T

274 ZOOLOGY.

rows under ground, have a foetid odour, and attack only small
animals. Species of the fox are to be found in all parts of
the world. Those of cold countries give a fur which is much
sought after.

[Notwithstanding the general resemblance of the fox and
domestic dog, a resemblance extending even to the structure of
the interior and the skeleton, they are yet so distinct from each
other as to entitle them to be placed in different genera. Recent
experiments seem to prove that they do not breed with each
other, so that they have in reality no consanguinity. The know-
ledge of this unexpected fact we owe to direct experiment, and
it is doubtful if science could ever have enabled the naturalist
or anatomist to have made the discovery. The bearing of this
fact on future palaeontological discoveries is extremely important.
A fossil skeleton might be found strictly resembling that of the
fox, the hasty theorist would declare it to have been a fox, and
that therefore the present geological era must have been of vast
duration ; another would pronounce it to have been a dog, whereas
in all probability it was neither one nor the other, but the remains
of an animal having no place in the present order of things. All
these errors originate in the unhappy attempts of modern
geologists to restore, as they call it, the extinct animals. — K. K.]

All the carnivora of which we have spoken, as well as many
others — the genette and civet, for example — walk on the ball of
the toes, the tarsus being raised. Hence the name of digiti-
grades ; and to this they owe their upright walk and rapidity.
Bears and badgers, in walking, place the entire sole of the
foot on the ground : hence they are called plantigrades.
Their movements are slow, and they lead a nocturnal life.

Bears are large, heavy animals, thick and short. The tail
is short, the limbs thick ; but they are animals of great
strength and sagacity. The form of their extremities enables
them to climb trees very readily, and t<$ sit erect on their
hind quarters. Some swim well, a quality they perhaps owe
to the fat with which their bodies abound. Of all the carni-
vora, they are those least restricted to an animal diet ; in fact,
they are omnivorous, for which, indeed, the character of their
teeth, almost all tuberculated, evidently adapts them ; such
teeth being more fitted to bruise roots and grains than to tear
the flesh of animals. Vegetable food is their regular diet,
and they prefer honey, of which they rob the bees, being well
protected from their stings by the roughness of their hides.
The greater number of the bears live in the forests, but one

OF THE CLASS MAMMALIA. 275

species frequents the shores of the Polar seas. The former
live in caverns or burrows dug by themselves, their strong
claws enabling them to do this. In extremely cold weather
they pass the time in a profound lethargy.

§ 415. The order called amphibia is formed of two genera,
the seal and walrus. In these animals, also carnivorous, the
feet are not adapted for walking, but for swimming: they pass
the greater part of their lives in the water.

[If my memory serve, my esteemed friend, De Blainville,
placed in a distinct class certain animals truly amphibious, as the
siren, proteus, axolotl, &c. Seals, otters, &c., are not strictly
amphibious. — R. K.I

Fig. 237.— The Seal.

§ 416. The order of cheiroptera is closely united to the
quadrumana, but have the pectoral extremities organized for
flight by means of a large fold of integument, extending from
the flank and tail to the extremity of the fingers (Fig. 238, 239).
The brain also is much less developed than in the preceding
groups. The dental system is still composed of incisives,
canine and molar teeth. Of the class some are frugivorous,
with molars resembling the quadrumana ; others insectivorous,
and in these the teeth are formed as in the following class.
The bats are the principal representatives of the group.

§ 417. The insectivora do not differ from the other ungui-
culated mammals, expecting in this, that the molar teeth are
evidently constructed for the crushing of insects, on which
they live. They are in fact rough, with conical points (Fig.
22), which adapts them for this purpose. Their brain rather
resembles that of the cheiroptera in having no convolutions,
than what we find in the bimana, quadrumana, carnivora, and
amphibia. The greater number make use of burrows, and
hybernate. We cite, as examples of the group, the mole
T 2

276

ZOOLOGY.

(Fig. 214), the hedgehog, the desman (Fig. 209), and the
shrew mouse, or musaraigne (Fig. 240).

Fig. 238.— Chauve-Souris Oreillard ; Large-eared Bat.

The hedgehog has the hody covered with spines or quills
instead of hair, and the skin of the back is provided with a
large oval muscle, so that the animal can roll itself into a ball,
thus presenting nothing but spines for the enemy to attack.
They live in the woods, and lie concealed during the day be-
tween the roots of old trees. They are common in France.

The shrew mouse is
a small animal, at first
sight resembling a
mouse. The body is
covered with hairs,
and on each flank is
a small band of stiff
hairs, between which
is secreted and exudes
an odorous humour.
They burrow under

Fig. 239.-Oreillard; Large-eared Bat FOUnd> a"d liv6 On

(walking on the ground). insects and Worms.

Tt is a popular error

to accuse them of giving rise to a disease in horses and mules
by their bite.

Moles are animals essentially subterranean and burrowing.
The body is thick and short ; their muzzle is elongated, and
terminated by a moveable snout, adapted to burrow ; and their
anterior limbs, though short, are extremely strong and broad,
turned outwards, and terminated by strong claws admirably
adapted to dig (Fig. 214). By means of these instruments,
moles dig, with great rapidity and admirable instinct, long

OF THE CLASS MAMMALIA.

277

galleries under ground, in which they dwell. Molehills are
formed of the product of these excavations. They seldom
quit their excavations, and live on insects and worms. De-
stined to live in profound dark-
ness, their eyes are scarcely
perceptible, and there is a
species of the mole which is
completely blind. The mole
has twenty-two teeth in each
jaw, or forty-four in all. The
common mole of the fields, of
a fine black colour, is common
throughout the fertile coun-
tries of Europe.

§ 418. The order rodentia comprises the ordinary ungui-
culated mammals which have no canine teeth, but have strong
chisel-shaped teeth in front, or incisive, and molar teeth behind.
This arrangement of the teeth (Fig. 243) adapts them for
gnawing very hard vegetable substances, as the bark and
roots of trees, and these in fact form their principal nourish-
ment. The brain of rodents resembles greatly that of the
insectivora, and their intelligence is very confined ; neverthe-

Fig. 240.— Shrew Mouse
(Musaraigne).

less, some are gifted with extraordinary instincts. Squirrels
(Fig. 118), marmots, rats, hamsters (Fig. 119), the campagnol
(Fig. 242), the porcupine (Fig. 195), and several other animals
similarly organized, belong to the order rodentia.

Kodents of the genus Mus are characterized by some pecu-

278

ZOOLOGY.

liarities in the disposition of the teeth, and by their long and
scaly tail. They are small animals, and live especially on
fruits and roots, but, pressed by hunger, they take to animal
food, and will even attack and devour each other. Three
species have become common in our houses : the domestic rat,
the surmulot, and the mouse.

Fig. 242. — The Field Vole ; Arvicola Agrestis ; Campagnol.

The rat was not known to the ancients, and seems to have
been imported into the Old World from America. The epoch
of its introduction is unknown, but it existed in great num-
bers where the surmulot now abounds. This latter seems to
have almost extirpated the common rat. It is now very rare
in Paris, and is to be found chiefly in barns, where it lives on
grains and vegetables of all sorts it finds there ; but it has
a decided taste for animal food, and it pursues young animals.
In country-houses it is a destructive plague, by the damage
it does to linen, harness, lard, and, in short, to everything
eatable which falls in its way.

The surmulot is the largest of the rats : it is of a reddish-
^s^=;_______.__ brown colour. Introduced into

fcrx^l Europe in the eighteenth century,
it has multiplied exceedingly.
Brought from India to England
by sea, it spread into France, and
thence into Europe, America, and
all the colonies. In the neigh-
bourhood of Paris they abound
in the common sewers, and dig

burrows just sufficient to hold the
F,g.243.-HeadofaEodent. ^^ •>

The mouse is the smallest of the species of rats which

OF- THE CLASS MAMMALIA.

279

infest our houses ; it was known to the ancients. It forms
galleries for itself in the timbers of houses in which it lives,
and feeds on whatever animal or vegetable substance it meets
with, but prefers suet, lard, and generally fatty bodies.
When inhabiting the woods in a wild state, it lives on acorns,
roots, and fruits.

Fig. 244. — The Lerot; Mus Nitela; the Dormouse.

[The Loirs (dormice) are pretty little animals, with soft hair,
velvety tail, ever tufted, with a lively look, which have a strong
analogy with rats, live in or frequent (se tiennent sur les arbres)
trees, supporting themselves on fruits. Like the marmots, they
pass the cold season rolled up into a ball, and in a very profound
lethargic sleep. They may be recognised by the number of their
molar teeth, which is four in each jaw and on each side. — Tn the
Dictionary of Fleming and Tibbins, 1841, these terms, Loir and
Lerot are thus defined : — " Loir, (Lwar) ou Liron, s. m. (sorte de
petit animal qui dort, a ce qu'on pretend, tout Phiver). Dormouse.
Loir volant (potatouche ou ecureuil volant), flying squirrel. Lerat
s. m. (espece de loir) musavellanarum, the smaller dormouse.

In the Decline and Fall of the Roman Empire, there is a note
at p. 265, vol. v. (Milman's edition), to the following effect :
"The want of an English name obliges me to refer to the common
name of squirrels,* the Latin glis, the French loir, a little
animal who inhabits the woods and remains torpid in cold
weather. (See Plin. Hist. Natural, viii. 82 ; Buffon, Hist.
Naturdle, torn. viii. p. 158 ; Pennant's Synopsis of Quadrupeds,
p. 289). The art of rearing and fattening great numbers of
glires was practised in Roman villa? as a profitable article of
rural economy (Varro, De Re Rustica, iii. 15). The excessive
demand of them for luxuiious tables was increased by the foolish
prohibitions of the censors ; and it is reported that they are still

* la it not the Dormouse ?— Milman.

280 ZOOLOGY.

esteemed in modern Rome, and are frequently sent as presents by
the Colonna princes (see Brotier, the last edition of Pliny, tome
ii. p. 458, apud Burbon. 1779)."— R. K.]

The jerboas (Fig. 245) are small rodents, remarkable for
the development of their hinder limbs, and this enables them
to leap with great agility.

The squirrel (Fig. 118) is also a rodent, and is known by
the length of the tail, furnished with hairs like a large quill
or feather. They live amongst trees, on fruits and nuts, and
are remarkable for their agility. There are many species
in the Old and New Worlds. In France the common squirrel
abounds, and retains throughout the year the colour by
which it is known ; but in the North it becomes, during
winter, of a fine ashy-blue colour, and the fur is much sought
after. In this state the fur is called petit gris.

Fig. 245 .—The Jerboa. '*

The beaver is distinguished from all other rodents by its
large tail, flattened horizontally ; it is of an oval form, and
covered with scales. The beaver is of a good size, aquatic in
its habits ; their feet and tail aid them in swimming, and
with their powerful cutting teeth they easily cut down all
sorts of trees. They live on bark and other hard vegetable
substances.

The Canadian beaver is, of all quadrupeds, that which
exhibits most industry in the construction of its dwelling,

OF THE CLASS MAMMALIA.

281

at which it works in society, in the most solitary parts of
North America (§ 331, p. 174).

The neighbourhood of man seems to prevent the beaver
from working in society, as we find that the beavers of the
Rhine are solitary, and never construct habitations like those
of Canada, although they seem to belong to the same species.
The beaver was formerly indigenous to many European
countries, and even to Britain.

§ 419. The order of edentata (toothless animals) seems
to fill up the link between the unguiculata and the ungulata,
for the nails acquire a great development, and cover a large

Fig. 246.— Head of the Armadillo.

portion of the extremity of the fingers and toes ; but that
which characterizes them is the absence of teeth in the front
of the mouth (Fig. 246).

The dentition is composed of canine and molar teeth only,
and even these are also sometimes absent (Fig. 29) ; the
edentata live, in fact, on soft insects, or leaves easy to gather.
As examples of this group, we cite the armadillos (Fig. 247),
the pangolins (Fig. 196), and the ant-eaters.

Fig. 247.— The Armadillo Cabassou ; the Tatou, or Tatouay of D'Azzara.

§ 420. The order of pachydermata belongs to the division
of mammals having hoofs, and is composed of all the ungu-
lata in which the stomach is formed in the usual way, and

282 ZOOLOGY,

not intended for rumination. They are remarkable for the
thickness of their skins ; they are all more or less herbi-
vorous ; and their brains have convolutions, as in the carni-
vora. Some have the nose prolonged into a proboscis, and
are for this reason called proboscidians : the elephants (204)
have this feature. Others are recognised by the feet ter-
minating in a single toe, covered with a hoof; the horse, ass,
and zebra offer this character, and hence the name of solipeda.
Finally, the ordinary pachydermata have the feet terminated
by fingers or toes, varying from two to four ; the wild boar,
the tapir (Fig. 208), the rhinoceros (Fig. 198), the hippo-
potamus (Fig. 251), belong to this class or group.

Fig. 248.— The Zebra.

The genus elephant (Fig. 204), the largest of all land
animals, is of a mild and gentle nature, and hence the ease
with which it may be domesticated. The great size of the
head and weight of the tusks necessitate a proboscis to enable
the animal to feed (page 243). By means of this singular
instrument the elephant uproots trees, unties the knots of a
cord, picks a lock, or uses a pen. Their sight is tolerably
good, their hearing fine, and their sense of smell acute.
Their caution is extreme, and their intelligence remarkable.
They remember injuries, and are not forgetful of favours.
Though of heavy gait, their speed is considerable, owing to
the length of their pace. Although the elephant is the most
powerful of quadrupeds, he is naturally neither cruel nor for-

OF THE CLASS MAMMALIA. 283

rnidable. Courageous in defence, he seldom attacks. By
nature he is gregarious, living in troops, varying from fifty
to one hundred, and is seldom seen solitary. The oldest
leads the troop, and the next in age brings up the rear.

Taken when young, they are readily trained to carry enor-
mous weights ; 2000 pounds weight is the load of the adult,
and they will perform with this a march of fifteen or twenty
leagues. They swim well, and live to nearly two hundred
years.

Fig. 249.*

Two species of elephants have been described, — 1, the
Asiatic ; and 2, the African. The first is known by its elon-
gated head, concave forehead, and comparatively small ears ;
four nails on the hinder toes ; the molar teeth also present
parallel ridges, nearly equidistant. The tusks often remain
short. 2. The African species (Fig. 207), remarkable for the

* Equus Burchellii — a species of Zebra discovered by Mr. Burchell;
attempts are now being made to domesticate the Daauw.

284 ZOOLOGY.

size of the tusks, development of the external ears, three
loose nails on the hinder toes, shorter head, and convex fore-
head. The surface of the molar teeth (Fig. 206) when in use
presents rhomboidal figures, hy which it may be at once dis-
tinguished from the Indian species. The female has tusks

Fig. 250.*

nearly as large as the male. It is a more active and ferocious
animal than the Asiatic, and is found from Senegal to the
Cape of Good Hope.

[There is abundant evidence in history to show that- the African
species of elephant extended at one time from the northern slopes
of the Atlas to the Cape of Good Hope. They were employed by
the Carthaginians as an instrument of war in their conflicts with
the Komans. — K. K.]

Ivory, properly so called, is furnished by the tusks of the
elephant, recent and extinct. When cut and polished, it
may be recognised by its numerous lozenge-formed curved
lines.

The hippopotami have an enormous body, with very short
limbs, four equal toes to each foot (the elephant has five) ;
tail of moderate length, nostrils dilated, skin almost hairless.

* Hemione, or Dziggetai; Equus Hemionus Pall; Native of Indostan
and Upper Asia. It has been acclimatized in France.

OF THE CLASS MAMMALIA. 285

They live on vegetables, and their habitat is the rivers of
Central Africa.* Their colour is a brownish black, and they
attain an enormous weight. Three or four may be seen in a
line in the river, near some cataract or stream, darting at the
fishes which the rapidity of the current brings near them.

Fig. 251.— The Hippopotamus; the River Horse ; Sea Cow of the Dutch.

They swim well and rapidly, and can remain a long time
under water. During the night they quit the rivers, and
feed on the herbage of the banks, or make their way to the
fields of rice or millet, which they rapidly consume. Their
march is so impetuous that they overthrow every obstacle,
especially when alarmed. Their character is ferocious.

Fig. 252. — Hippopotamus.

The pig has also four toes on all the feet, but two are large
and two shorter.' The incisive teeth vary in number, and
the tusks protrude from the mouth, curling upwards. The

* Southern and Northern as well.— E. K.

286 ZOOLOGY.

muzzle terminates in a truncated snout, adapted for digging
up roots, on which they live, in troops, in the forests ; but
they show no repugnance to animal food.

The rhinoceros (Fig. 198) is a very large animal, with a
short thick body and short limbs, remarkable for the great
thickness of its hide, and for the horn or horns it carries on
the nose. The horns are solid, composed of matted hairs,
and supported on strong nasal bones, arched and thick ; but
these horns have no osseous core, and they move with the
integuments. It inhabits the hottest parts of Asia and
Africa, and is generally found in the elephant countries. It
is ferocious and untameable, and is fond of wallowing in miry
places, like the pig (Fig. 199).*

Fig. 253. — Head of a Young Hippopotamus of Southern Africa;
from a drawing by Burchell.

The genus horse, comprising the horse, properly so called,
the ass, zebra, and several other species, is characterized by
the conformation of the feet, single toed, and covered with a
hoof; by six incisives in either jaw, hollowed when young,
which hollow disappears with age ; by^ix molars on either
side of each jaw, and by a space or bar between the small
canine teeth found in the male and the molars, which receives
the bit. These canine teeth are small, and peculiar to the
male. The eyes of the horse are prominent, his hearing good,
upper lip so large as to be used as an instrument of prehen-
sion ; nostrils not much dilated ; the body is covered all over
with hair, and the neck provided with a mane. The tail is
of moderate length, but has long hairs, especially in the

* The double-horned rhinoceros is peculiar to Africa, and was known to
the Romans. After all traces of it were lost to the civilized world, and its
very existence doubted by naturalists, it was rediscovered a few years ago
by Sparrman, in Southern Africa.— R. K.

OF THE CLASS MAMMALIA. 287

domestic horse. Though strictly herbivorous, their stomach
is simple, and of moderate size. His mode of life in a
domestic state is so well known as to require no description.

The horse, properly so called, is distinguished from the
other species by the uniform colour of the coat ; by the tail,
furnished with hairs from its basis ; by his height and more
elegant form. He exists nowhere now in a wild state, for the
so-called wild horses of America are merely the domestic
horse abandoned by man ; and although their introduction
into the New World is of no earlier a date than three hun-
dred years, they are said to be found in troops mustering ten
thousand.

The. horse lives to about thirty years ; he ought not to be
employed for saddle or draught before four or five. When
aged he loses most of his valuable qualities ; and hence the
importance attached to the age. He is called aged when the
little cavities found in the incisives have disappeared by tri-
turation : this happens at eight years ; after that he is said,
to have lost the mark.

Fig. 254.— The Bison.

The ass is recognised by its height, tufted tail, dark cross
on the shoulders, and long ears. More temperate and patient
than the horse, he is not so strong, but still very useful as a
beast of burthen. Comparatively he is both stronger and
more hardy. He is choice in the water he drinks, but in
nothing else, and he sleeps less than the horse. His stupid
and obstinate nature seems mainly due to the bad treatment
he receives; in the duration of life the ass resembles the
horse.

288

ZOOLOGY.

§ 421. The order ruminants is distinguished from all the
preceding groups by their complex stomachs. These animals
are essentially herbivorous ; they have no incisives in the
upper jaw ; in them the foot is divided or cloven, and it is

Fig. 255.— Skeleton of the White or Wild Ox of Scotland.*

amongst this species especially that the forehead is armed with
horns. The ox, sheep (Fig. 263), goat, and stag (Fig. 264)
chiefly represent the class; but the antelope, giraffe (Fig.
271), camel, lama, &c., are included in the group.

The genus ox differs from
other ruminants by the form
of the body and the direction
of the horns.

The principal species are
the common ox ; the aurochs,
originally both European; the
buffalo, the yack, peculiar to
Asia ; the bison and the musk
ox, peculiar to Northern
America.

The common ox, when
young, is called a calf, the
male a bull, the female a cow ;
its forehead is flat, longer than

Fig. 256.— Head of Young Scotch
Bull.f

* From the drove belonging to the Duke of Hamilton. — R. K.
t Head of the Ox called Urus Scoticus, or Wild Ox of Caledon, drawn
from a specimen of the breed preserved in the Forest of Cadzow, and belong-
ing to the Duke of Hamilton. They are of a dun white colour, with black
ears and hoofs. I ascertained many years ago that the purity of the breed
is preserved by destroying all calves which are differently coloured.— R. K.

OF THE CLASS MAMMALIA.

289

broad; the horns are rounded and project from the extremities
of the prominent line separating the frontal from the occipital
bone. There exists scarcely an animal so. useful to man as the

Fig. 257-*
White Ox of Scotland.

Fig. 257a.f
Common Ox of Scotland.

Mg. 258. — Alpaca.

* Skull of the Urus Scoticus; it is much shorter and broader across the
forehead than the common domestic ox, and the nasal bones also are much
shorter and somewhat differently arranged. — R. K

f Cranium of the common ox, to contrast with the above. — B. K.
U

290

ZOOLOGY.

ox : on this we need not dwell. The flesh is excellent ; he
can be made to labour like a horse ; the bones, skin, horns
hair, all are of use. The fat is fine and delicate, and the,
blood is used as a fertilizer, and also in the manufacture of
Prussian blue ; it is in use moreover as a refiner of sugar and
fish oil. The intestinal membrane is employed in the arts of
the gold-beater and to cover air balloons. From the milk of the
cow we obtain butter, cheese, and cream; with the stomach
called rennet we curdle milk. The ox is now found in every
part of the world, but no doubt it belonged originally to
Europe and Asia.

Fig. 259.— Llama.

The aurochs is the largest of European quadrupeds. It is
distinguished from the domestic ox by its convex forehead,
broader than long ; by the point of attachment of the horns,
lower than the occipital crest ; by a kind of woolly hair cover-
ing the head and neck of the male ; by a short beard under
the throat ; and finally, by having an additional pair of ribs.
It is not the origin of our domestic cattle. Formerly abound-
ing all over Europe, the race is nearly extinct, being confined

OF THE CLASS MAMMALIA,

291

to the marshy forests of Lithuania, of the Krapacks, and the
Caucasus.

The buffalo, of Indian origin, but now naturalized in Italy
and Greece, has the horns marked anteriorly by a longitudinal
crest. The buffalo is less docile than the ox, but he is
stronger and easier supported. He swims well (as does the
ox), and likes to wallow in muddy waters ; and he will dive
ten or twelve feet, tearing up with his horns aquatic plants,
which he eats while swimming.

Fig. 260.— Buffalo.

[The buffalo, presumed to be of Asiatic origin (like the ox),
has been long domesticated in Africa a ad in Italy, into which
country it was introduced in 595 or 596. — R. K.

Fig. 261.— Male Yak.*
* From Thibet : now being domesticated in France.— R. K.

u2

292

ZOOLOGY.

The yak, also called the buffalo with a horse's tail, the
grunting cow of Tartary, is a small species originally from
Thibet. It has a long mane, and a tail with long hairs like
the horse. It is with this tail that the standards are made
which, with the Turks, serve to distinguish the superior
officers.

The musk ox is an inhabitant of
the more northern parts of North
America. It climbs over rocks like
a goat. Its odour is peculiar ; hence
the name ; and its horns are united
in the middle of the forehead.

The American bison strongly
resembles the aurochs, but has the
limbs shorter, and differs in some
other respects, as in having the
hair longer.

The genus sheep (ovis) differs

but little from the goat. Their horns are disposed to
become spiral ; they have no beard, and have the forehead
convex.

A wild species, called argali, with very large horns, seems
to be the original of the domestic sheep. They are found in

Fig. 262— Musk Ox.

Fig. 262a.— Angora Goat.*

great numbers in Kamtschatka ; in all the lofty mountainous
regions of Asia ; in the higher ranges of those of Barbary,

* It is being now domesticated in France.— R. K.

OF THE CLASS MAMMALIA. 293

Corsica, and Greece. It grows to a large size, and is very
agile.

The mouflon (Fig. 263), found in Europe and Africa, differs
from the argali in this, that it never attains the same size.

Fig. 263.— The Mouflon ; Ovis Musimon. The Wild Sheep of Sardinia.

Fig. 264.— The Stag.

The female rarely has horns, and when present they are small.
Varieties of the mouflon exist. Some are white, others more
or less black. They live in troops.

294

ZOOLOGY.

The domestic sheep when young is called a lamb : the
female is called an ewe : the male, a ram ; it is too well known
to require any zoological description. The variety called
merino, remarkable for the fineness of its
fleece, and at one time limited to Spain,
has been extensively introduced into
France and Germany, both as a pure
breed and as crossed with others. Five
hundred thousand of the pure breed exist
in France. The clip takes place in the
month of May.

The goat resembles the sheep as re-
gards the horns ; but it differs in the
direction they take. Its chanfrein, or
face and head, is concave, and it has a
beard. All the species of this genus
belong to Europe and Asia; they live in
small troops amongst the rocks, and dis-
play astonishing agility.

The segagre, or wild goat, seemingly the origin of all the
domestic species, lives in troops in the mountains of Persia,
and perhaps even amongst the Alps.

Fig. 265.— Head of
Antelope Canna.*

Fig. 266.— Gnu or Wildebeest of the Dutch Colonists.!

The bouquetin is another wild species inhabiting the sum-
mits of the lofty mountains of the Old World.

The domestic goat prefers rocky ground as a habitat : its
milk is less apt to curdle in the stomach than that of the cow,

* Hartebeest of the Dutch Colonists of the Cape of Good Hope; an Antelope,
t I saw them in -vast droves on the Great Bonlebok Plain, to the North of
the Wenterbergen, Cape of Good Hope. — R. K.

OF THE CLASS MAMMALIA.

295

and is thus esteemed to be of easier digestion. It is a fearless
animal, dreading neither heat nor cold, storms nor rain.

Deer are ruminants, characterized distinctly by the shed-
ding of their antlers. The species abound, — such as the

Fig. 267.— African Antelope.

Fig. 268.— Eland of the Cape ; the largest of the South
African Antelopes.

common or fallow-deer, the red-deer, the roebuck, the rein-
deer, &c. They all inhabit the forests, and are remarkable for
their speed and for the elegance of their forms. The antlers,
generally peculiar to the male, are cast in spring.

The antelopes resemble deer in many respects, but are

296 ZOOLOGY.

readily distinguished from them by having persistent horns,
like goats and sheep. The chamois belongs to this group.
The gira i ? distinguished from all other ruminants by

Fig. 269.— Striped Eland <

Fig. 270.— The Kern- Deer.

* Striped Eland, discovered by Dr. Livingstone within the tropics, to the
north of the Cape Colony. What is remarkable in the history of these two
species or variety of the Eland is that the young of the Cape Eland is striped
like the northern species, but the stripes disappear as the animal becomes
adult.

OF THE CLASS MAMMALIA.

297

the form of the body and the nature of its horns, which are
conical, osseous, and always covered with the integuments.
It measures from fifteen to seventeen feet in height, and the
single species as yet known is peculiar to Africa.*

Fig. 271.— The Giraffe.

* In Southern Africa it is never seen to the south of the Great Orange
River.— K. K.

298 ZOOLOGY.

The camel is remarkable for the enormous mass of fat
found on the shoulders and back, single or double. Of the
camel there are two species — the Bactrian with two humps,
and the Arabian or dromedary with one. Their feet are

Fig. 272.— Tongue of the Camel Leopard.

Fig. 273.— Cells of Llama's Stomach.*

peculiar, the two toes being reunited nearly to the points by
a strong sole, admirably fitted for traversing sandy deserts.
Without the camel, man could with difficulty have traversed

* Peculiar cells or pouches in the stomach of the Llama ; they strictly re-
semble those which were supposed to be peculiar to the Camel. — E. K.

OF THE CLASS MAMMALIA. 299

the deserts of Asia and Africa. It is exceedingly temperate
as to the use of water, a quality which has been ascribed to
the peculiar form of its stomachs ; in two of these large cells
exist, which either serve as reservoirs or which have the
power of secreting water. In Arabia it is held to be the
most valuable of animals. Of the long hair which it casts
annually, the Arabs make tents and clothing ; they use the
milk ; and as a beast of burden and of sudden flight it is
invaluable.

Finally, the llama, of which there are several species, is
peculiar to South America. It resembles the camel in many
respects, and especially in the structure of its stomach ; but
it has no hump.

Fig. 274.— Sperm Whale.

§ 422. The fish-formed mammals comprise only a single
order — that called cetacea. They are strictly aquatic, and
resemble fish somewhat in their forms. In these the pelvic
limbs are wanting, and the pectoral are converted into

Fig. 275.— Skeleton of the Korqual Giganteus.*

swimming paws or fins ; the tail is terminated by a broad
horizontal flipper composed of two flanges. The marsouins
(porpoises) (Fig. 193), the dolphins, the cachalots, (sperm

* This specimen was dissected by myself and brother ; it measured eighty
feet in length. The upper jaw and cranium weighed a ton and a half; the
lower jaw-bones two tons.— R. K.

300 ZOOLOGY.

whales,) and the balsense, (whalebone whales — balaenae and
rorqual,) or whales properly so called, belong to this group.

The whales are enormous cetaceans, whose head forms
about a third of the length of the whole body. In the mouth
there are no teeth, but numerous plates of whalebone depend
at the sides from the mucous surface of the upper jaw. They

Fig. 276.— Head and Tail of Balaenoptera rostrata.*

are so arranged as to form towards the mouth a sieve,
calculated to retain very small animals, on which indeed
these huge cetaceans live. The volume of water they take into
the mouth is expelled through the nostrils ; hence the name
of blowers and blow-holes given to their anterior or superior
nostril s.f Contrary to what might be imagined, these enor-

Fig. 2774

* Sketches made by Mr. E. Forbes, who at that time acted as my.
assistant.

t It has been shown by Scoresby, myself, Beale, and a number of other
observers, that the pretended jet d'eau is merely the vapour from its lungs.

t Head of the Eorqual of Fabricius; a whalebone whale. Drawn by
Edward Forbes.

OF THE CLASS MAMMALIA. 301

mous animals live generally not on fishes, but on small mol-
lusca, Crustacea, zoophytes, and generally the lowest marine
animals. They swim rapidly, and are timid and fearful ;
hence they are easily destroyed by the whalers.

There are several species of whalebone whales, but that
which is most sought after, by reason of the length of whale-
bone and the abundance of blubber it possesses, is the Green-
land whale, or whale of commerce ; formerly perhaps abun-
dant in the European seas, but now driven by persecution to
take refuge in the Northern and Polar Seas. It has no dorsal
fins.

Fig. 278.— The Whale of Commerce ; Balaena Mysticetus, or Greenland
Whale.

The cachalot or sperm whale has teeth only in the lower
jaw, and no whalebone. The enormous size and singular form
of the head of the cachalot is owing to a vast collection of oil,
which, when cold, becomes fixed, and forms the substance called
spermaceti. It is situated in cavities occupying the upper
part of the face and head. These cavities are supported late-
rally by largely developed upper jaw-bones, which give to the
skeleton of the head a very peculiar appearance.

The whale fishing, an important branch of commerce, and
in which the boldest sailors are trained, was at one time in
the hands of the Basques, but now almost exclusively belongs
to the English and Americans. The vessels proceed either
north or south. The northern fishery has for its object the
capture of the mysticetus, or Greenland whale. In the stormy
seas of the North, the whaler attacks the whale with the
harpoon. The blubber is found immediately beneath the

302 ZOOLOGY.

integuments, and indeed may be considered as forming a
portion of them. No fat exists in the interior of the whale,
but the bones, especially those of the head, afford much oil.

Fig. 279.— Foetus of Greenland Whale.*

The South Sea Fishery has for its object the capture of the
cachalot or sperm whale, and is carried on mostly in the
Pacific and Japan Seas. The spermaceti is the object sought
for.

The dolphins and the marsouins (porpoises) have the head
much smaller than the true whales, and they have teeth in
both jaws ; they are extremely carnivorous. Lastly, there
are cetacea which are herbivorous ; these are the lamantins
and dugong.f

[Tabular view of the number of vertebrae in the class
Cetacea.

Balsena Mysticetus Australis .... 59, Cuvier.

Balsena Mysticetus Borealis (adult) . . Unknown.

Balsena Mysticetus Borealis (foetus) . . 48, Knox.

Rorqual Giganteus 65, Knox.

^rqualofFabricius V j f^ l^nter.

Rorqual of the Cape 52, Cuvier.

Rorqual of Rudolphi 54, Rudolphi.

Cachalot 60, Cuvier.

o I Dueroner

56, Knox.
48, Home.

1

"o 1 Manatee of America

52, Cuvier.
46, Cuvier.

fc V

48, Home.

* Drawing of the foetus of the Mysticetus Borealis, abdominal surface,
from a specimen brought from the North Seas at my request by Mr. B.
Auld. It was removed from the uterus after the death of the parent. — E. K.

•f The Lamantins and Dugong are certainly not Cetaceans, as I proved
long ago. See Tr. R. Soc. Edin. 1830.— R. K.

OF THE CLASS MAMMALIA.

303

Manatee of Senegal Unknown.

Delphinus Delphis 67, Cuvier.

Delphinis Grisens 61, Cuvier.

Dolphin in our Museum 81, Knox.

Dolphin in Dr. Hunter's Museum, Glasgow 90, Knox.
Dolphin dissected by Mr. John Hunter, \

and considered by him as the D. Delphis, J 60, Hunter.

but by M. Cuvier as the D. Tursio .

Phocaena.

N.B. — This discrepancy in the number of
Phocaena may be specific ; but this is not likely.

66, Cuvier.
65, Knox.
51, Hunter,
vertebrae in the
— E. K.]

§ 423. The division of the mammalia called didelphian,
is characterized by physiological distinctions of great impor-
tance. In general the young are born prematurely, as it
were, and exceedingly imperfect, and they seem, whilst in the
womb, not to be nourished by a placenta, as is the case with

Fig. 280.— Kangaroo.

all the monodelphs. The brain is comparatively smooth,
and without a corpus callosum ; and marsupial bones attached
to the pelvis (Fig. 212), give a peculiar character to the
skeleton.

This group is composed of two orders — the marsupial and
monotremes.

304

ZOOLOGY.

§ 424. The order marsupialia is chiefly characterized by
the presence of a sort of pouch, destined to hold the young
whilst attached to the nipple, and during the early period of
their growth. A description of this pouch, with a drawing
of the form of the marsupial bones, will be found in Fig. 194.
The food of the marsupialia is various, some being insectivo-
rous, others herbivorous, others carnivorous, whilst some
strongly resemble the class rodents. They nearly all belong to
Australia and Tasmania. The opossums (Fig. 194), the
phalangers, and the kangaroos (Fig. 280), chiefly represent
the group.

--^rrsit /

Fig. 281.— The Oniithorynchus.

§ 425. Finally, the order called monotremes seems to
connect the mammal with the oviparous vertebrata. The
intestine terminates, as in birds, in a cloaca, and the repro-
ductive organs present many anomalies. The dental system
is rudimentary, and in some a horny covering of the jaws
gives to them the appearance of a duck's bill. As yet only
two genera of this singular class is known ; the ornitho-
rynchus (Platypus, or duck-billed animal) (Fig. 281), and
the echidna.

THE CLASS BIEDS. 305

[There is in the ornithorynchus, on each side a femoral gland and
duct leading to the spur on its heel. The secretions of this gland

Fig. 281a.

were at one time supposed to be poisonous. The apparatus is of
the most singular character, and was first described by me in the
Tr. Wern. Soc.— R. K.]

THE CLASS BIRDS.

§ 426. The class birds is one of the best defined and most
distinct, whether viewed with reference to the exterior or
interior. Birds are oviparous vertebrate animals, with a
double and complete circulation ; to which may be added, that
the respiration is aerien and double; which means, that instead
of being confined to the lungs, as in mammals, the air pene-
trates throughout the body, and even into the interior of the
bones ; their blood is hot, as in mammals. Finally, they are
covered with feathers, and their pectoral extremities have the
form and character of wings.

Birds seldom attain a great size, and their bodies are light
in consequence of the penetration of the air into their interior.
They do not vary much in their internal structure.

§ 427. Feathers are analogous to hair, but are more com-
plex in structure. A horny tube is first observed, pierced at
its extremity, a stalk surmounting this tube. Finally, barbs,
growing from the sides of the stalk ; these are fringed with
barbules ; and these again are sometimes fringed with others
still smaller.

The secreting organ of the feather is called the capsule. It

306

ZOOLOGY.

would seem that so long as the feather grows, or is being
developed, the capsule increases in length, and that in pro-
portion as its base elongates, the extremity dies, and dries up
so soon as it has formed the corresponding portion of this
appendage. Each of these small apparatuses is composed of a
cylindrical sheath, covered internally by two tunics, united by
oblique septa, and of a central bulb. The substance of the
feather is formed on the surface of the bulb, and to form the

Fig. 282.— Galeated Cassowary.

barbs it is moulded, as it were, into the spaces which the
small septa leave between them. In the corresponding por-
tion of the stalk, the bulb is in relation with its inferior
surface, and dies; but where the stalk of the feather is
tubular, the lamina of borny matter which the bulb pro-
duces turns entirely round it, and envelopes it completely.
Nevertheless, the bulb, as it fulfils these functions, still
dries up and dies, and thus withering successively it forms
a series of membranous cones set into each other, which

THE CLASS BIRDS. 307

fill the interior of the tube, and are called the soul of the
feather.

The young feather is at first enclosed within the sheath of
the capsule, which often projects several inches beyond the
integuments, and is gradually destroyed. The feather then
appears uncovered, and its barbs, at first rolled up, spread out
laterally. The extremity of the quill remains embedded in
the dermis, but generally may be readily detached, and at a
certain period falls, to be replaced by a new feather. This
renewal of the feathers is called moulting, and takes place
annually, soon after the season for laying the eggs ; but
sometimes it occurs twice in the year. At that period the
bird loses its voice, and is ill at ease.

The form of these integumentary appendages varies much;
some resemble the spines of the porcupine. In the wing of
the cassowary are four or five such ; in others, as in the eagle
and raven, the barbs are stiff, and provided with barbules,
which being interlocked with those of the adjoining feather,
prevents the passage of the air through them. In others, as
in the tail and wings of the ostrich, the barbs and barbules are
long, soft, silky, and apart. Finally, in others they resemble
a kind of down, and this may be seen in certain storks, which
are known by the name of marabouts, or pouched adjutants.
Their colours vary infinitely, and often surpass in beauty the
finest flowers or precious stories. The plumage of the male
is generally more brilliant than that of the female ; and it
seldom happens that the young bird preserves the same
character of plumage throughout life. They often change,
for two or three years consecutively, and sometimes the adult
has a summer and winter plumage quite distinct. Finally,
aquatic birds have their plumage besmeared with an oily fluid,
rendering them impenetrable to water, and thus preserving
the skin underneath.

§ 428. The skeleton is composed of nearly the same ele-
ments as in mammals, but the form and disposition of many
of the bones are different, and, cceteris paribus, their bones
are much lighter than those of mammals, being more or less
filled with air.

The head of birds (Fig. 284) is generally small ; in the
young bird the cranium is composed of the same number of
bones as in mammals, but they unite very early together, and
the sutures disappear. The face is in a great measure formed
of the jaws, which are much elongated, and being chiefly em-
x 2

308

ZOOLOGY.

ployed by the bird as instruments of prehension, vary exceed-
ingly in their character, according to the nature of the bird, the
food it lives on, and the prey it attacks. The superior man-
dible is so articulated with the cranium as to admit of motion in
the cranium, independent of the lower jaw, which never occurs
in mammals ; and the inferior, instead of being articulated
directly with the cranium by means of condyles, is connected

Sacrum. Scapula. Humerus.

Coccyx

wain vw^ // m A'^Bii MI i/ m M/O^LMT/^A m

ClaTicle.

^ _.r~=-_ «_,.„=—« Sternum.

Tibia.

Tarsus

Fig. 283.— Skeleton of the Goeland. Black-headed Gull.

therewith through the intermedium of a distinct bone, called
tympanic or os quadratum, generally considered to be a
portion of the temporal bone (the osseous meatus), and remain-
ing distinct throughout life. Moreover, each branch of the
lower jaw is composed of two segments, and it is by a fossette
that it articulates with the tympanic bone.

THE CLASS BIEDS. 309

The mode of articulation of the head with the vertebral
column admits of much more extended movements in birds
than in mammals ; the articulation is formed of a single con-
dyle, a sort of semi- spherical pivot placed in the mesial line
of the body, and received into a corresponding articular cavity
in the atlas.

Orbit. Inter-Orbitar Septum,
i /

Lachrymal Bone.

^^^^ J^— Cranium.

Sup. Maxil.

" '"Exoccipital.

Os Quadratum,

_ or Tympanic.

IS asal Fossae. JugalBone. Infer. Maxil.

Fig. 284.— Skeleton of the head of the Eagle.

§ 429. The neck in birds is generally much longer than
in mammals. The higher they are elevated on their limbs,
the longer must the neck become, the jaws being the principal
organs of prehension (Fig. 283) ; in the swan, the neck ex«
ceeds the height of the body, thus enabling it to seek its
prey at considerable depths while swimming. Thus the
number of cervical vertebrae varies greatly, according to the
species ; from twelve to fifteen is the usual number, but there
may be fewer, and occasionally there are as many, or more,
than twenty; they are extremely moveable on each other,
and this they owe to the forms of their articular surfaces.*
This arrangement is remarkable in wading birds, as in storks ;
numerous processes for the insertion of muscles assist in these
motions.

On the other hand, in almost all birds the vertebrse of the
back are nearly fixed or immovable, and this, no doubt, is to
enable the wings to find in this part of the trunk a point of
support. In general, they are consolidated or united into
one, but in birds which do not fly, as the ostrich and cassowary

* These articular surfaces are concave on one aspect and convex on the
other (ball-and-socket). In the upper part of the neck they permit of free
flexion forwards, but about the middle of the neck they admit only of
flexion backwards ; whilst again, towards the base of the neck, they admit
only of flexion forwards.

310

ZOOLOGY.

(Fig. 161), they remain distinct, and preserve their mobility.
The lumbar and sacral vertebrae unite into one ; the coccygeal
are small and moveable, the last generally larger than the

Fig. 285.--Breastbone of Swan.

Fig. 286.— Merrythought of
the Turkey.*

others, and is raised into a crest. It
supports the large feathers of the
tail (Fig, 283).

§ 430. The ribs of birds show
some peculiarities tending to give
solidity to the chest or thorax. The
cartilage uniting the rib to the
sternum is osseous in the bird, and
each rib has a process, which running
backwards over the other rib, so
overlaps them that all the ribs sup-
port each other.

But the most remarkable part of
the skeleton of the thorax is the
sternum (Fig. 287), which, giving
attachment to the muscles used in
flight, assumes ..an extraordinary
development, enclosing not only the
thorax, but a large part of the
abdomen. In the cassowary and
ostrich (Fig. 161) which do not fly,
the sternum has no external crest,
and the wings are rudimentary ; but
this crest exists in other birds, and

* A very prevalent vulgar error is that the turkey has no merrythought,
this being the common name given to the clavicles which rest on the
sternum. Subjoined is a drawing of the furculum, or "merrythought" of
the turkey, and of the clavicles supposed to be wanting. — E. K.

THE CLASS BIRDS. 311

is called the keel or brecJiet (b, Fig. 287) ; by multiplying the
muscular attachments favourably, it gives more force to the
depressor muscles of the wings.

§ 431. The bones of the shoulder are in like manner
favourable for the action of the wings. The scapula (o) is
narrow and elongated, and placed in the axis of the spine ; it
rests on the sternum not only by the clavicles called four-
chette or merrythought (/), but also by the clavicles called
coracoid (c), so termed because they seem to be prolongations
of the coracoid process in man. The clavicles called fourchette
unite generally below with each other, and are attached to the
crest of the sternum, and, together with the powerful coracoid

Fig. 287.— Bones of the Shoulder and Sternum, in the Bird.*

clavicles offer a strong point d'appui for the wings to acton,
and these structures are proportioned to the power of flight of
the bird. Thus in some of the terrestrial parroquets of Aus-
tralia these bones are reduced to an almost rudimentary state,-
in the cassowary and American ostrich the fourchette is repre-
sented by two small stylets ; in the African ostrich and
the tiican they nearly reach the sternum, but do not unite
inferiorly ; finally, in some owls they are united inferiorly by
cartilage, whilst in the greater number of birds their bony
union is complete. In many instances they form a crest at
this point of union, and seek a direct support from the
sternum.

The anterior extremities of birds are employed only as

* s, the sternum ; e, notch of the sternum ; co, origin of the sternal ribs ;
b, crest ; f, fourchette ; c, coracoid clavicle ; o, scapula j t, fibrous mem-
brane extending from the fourchette to the sternum.

312 ZOOLOGY.

wings ; they must not be confounded with the so-called wings
of bats, which we have already seen to be of an entirely dif-
ferent nature : they are formed of stiff feathers or quills,
which require to be fixed only at their base, and the hand in
consequence ceases to present any appearance of fingers.

§ 432. The large quills of the wings are called remiges,
and it is more on their length and strength than on the extent
of the bones, that the power of flight depends. Each time
the bird prepares for flight he raises the arm and its plumage
unfolded ; then he enfolds it by extending the arm, at the
same time suddenly depressing it : the air which is struck
forms the point of support and resistance to a downward
movement ; upon it he rises like a projectile, and the impul-
sion once given to the body is maintained and directed by the
same instruments and movements : the bird would soon fall
to the earth by the force of gravity, but before the speed
acquired by the first effort is exhausted, a second and a third
take place, continuing the living projectile in its course.

b

Fig. 288.— Wing of the Falcon.*

Whilst the bird is being thus suspended in the air, it
becomes necessary for it to maintain its equilibrium in this
position ; and in order to secure this, its centre of gravity
(§ 285) must be placed under the shoulders, and as low as
possible ; for this reason, during flight the bird carries the
head well forward, the neck being on the stretch, and the
body heaped together, as it were, into an oval form.

It is obvious, on the plainest mechanical principles, that, all
things being equal, the faculty and power of flight will be in
the ratio of the extent of the wings, these being the moving
force ; and in fact all birds remarkable for their power of
sustaining a long and rapid flight have large wings, the oppo-
site being the case with birds of low, slow, and short flight ;

* a, remiges, or primary quills of the hand ; b, secondary quills, or those
of the fore-arm ; dy bastard quills, or those of the thumb.

THE CLASS BIBBS.

313

the condor (American vulture, Yulture of the Andes) and the
sea bird called frigate, are good examples of such powers of
flight. The dwelling of the condor is on the lofty peaks of
the Cordilleras, from whence he descends to the ocean at a
sweep, regardless of the effect of rapid changes in the tem-
perature and in the pressure of the atmosphere. They are
said to be strong enough to carry off in their talons sheep
and llamas, and when united in numbers, to attack and kill an
ox.* The birds called frigates have the wings proportionally
longer, and are met with in tropical seas at the distance of
four hundred leagues from land.

Fig. 289.— The Frigate Bird j Pelicanus Aquilus.

To rise vertically, the wings of the bird must be carried
horizontally; but this is seldom the case, and from the
obliquity of their position they impress on the motions of
the bird an oblique ascensional movement : occasionally this
obliquity is so great that, in order to rise vertically through
the air the bird is obliged to fly against the wind. The
relative length of the remiges influences the facility with
which the bird rises in calm air. Birds which have the ante-
rior remiges the long-est and most resistant, have a more

* The South African Vultures, which I have seen in vast numbers in
Southern Africa, have the same habits ; they are a cowardly bird, not-
withstanding their strength and size. — R. K.

314

ZOOLOGY.

oblique flight than those which have the wings truncated at
the extremities.

Thus the falcons (Fig. 288), which have the wings pointed,
rise only in zigzag, like a vessel tacking : whilst the hawk,
eagle, and other birds of prey, called base or ignoble, whose
wings are truncated at the extremities, can rise vertically
through the air.

Fig. 290.— Wing of the Sparrow Hawk.*

In rising from the soil, the bird first springs or leaps from
the ground by means of his feet ;
if these (the limbs) be too short,
as in the case of the martinets,
they find it difficult to make the
first bound, and seek a declivity
to enable them to have room for
the expansion and action of their
wings.

Birds in their flight are assisted
by the tail feathers, which seem
to act as a rudder in directing
their course.

§ 433. When resting on the
soil, the bird is strictly a biped,
and hence the necessity for a
broad and large pelvis, firmly

Fig. 29i.-Pied Woodpecker ; £xed *? &* vertebral column The
Picus. haunch bones are, in fact, ex-

* a a, primary quills; J, secondaries.

THE CLASS BIKDS. 315

tremely developed in birds, and they form, with the lumbar
and sacral vertebrae, a single osseous mass (Fig. 283). In
general this osseous girdle is incomplete anteriorly; the
bones of the pubis do not unite with each other in front,
whilst the ischiatic portions unite with the sacrum, so that
the so-called notch in mammals becomes in birds a foramen
or hole. The thigh-bone is short and straight, and the leg
is composed, as in mammals, of a tibia, fibula, and rotula ;
but the fibula is united to the tibia before reaching the lower
part of the leg. A single bone represents the tarsus and
metatarsus ; this supports or carries the toes, never more

Fig. 292.— Apteryx of New Zealand.

than four in number ; sometimes the great toe disappears,
and occasionally the one next it, thus leaving three or only
two (Fig. 282). The number of the phalanges increases pro-
gressively from within outwards, from the great toe to the
external or fourth, from two to five. Finally, of these four
toes, three in general are directed forward, the thumb or
great toe being turned backwards ; but sometimes the
external toe is also turned backwards, as especially in
climbing birds, the parroquets, tucans, and woodpeckers, &c.
(Fig. 291).

Whilst the bird rests upon its feet on the soil, it is neces-
sary that the centre of gravity fall within the base of susten-
tation ; hence the utility of the extremely flexed thigh and
the obliquity of the tarsus on the leg. When the foot is
large and broad, and the neck is so flexible as to carry the

316

ZOOLOGY.

head well backwards, the equilibrium may be thus maintained
without abandoning the horizontal position (Fig. 293) ; but
when the neck is short, the head large, and the toes of mode-
rate length, the bird is forced to maintain an almost vertical
position (Fig. 294). To maintain their equilibrium, birds
place the head under the wing whilst they sleep perched on
one foot (Fig. 306). The mechanism by which they stand
with such ease and for such a length of time on one foot, is
this : the lower extremity of the femur presents a hollow, in
which is lodged, during the extension of the limb, the top of
the tibia, which cannot quit this cavity but by a muscular
effort. The foot once spread out, remains so, requiring no
further muscular effort, and consequently giving rise to no
fatigue.

Fig. 293.— The Ibis.

Fig. 293a.— Egyptian Ibis.

[Sacred Ibis of the Egyptians, as we find it represented on the
walls of a temple in Upper Egypt, thus proving, according to M.
Cuvier, that the Ibis we now find by the banks of the Nile is
precisely the same as existed at least 4000 years ago. Together
with this outline by the Coptic artist, M. Cuvier, in his great
work (Ossemens Fossiles) gives a drawing of the Numenian Ibis of
modern zoologists which he considers as the identical sacred Ibis
of the Egyptians. The Ibis represented in Fig. 293 I take to
be a drawing of the Numenian Ibis. I met with various species
of the Ibis in Southern Africa by the banks of the Great Fish
River, Bosjieman River, &c. They frequented the kraals of

THE CLASS BIEDS.

deserted farm steadings, on which they sought their food,
coloured natives called them "Hadada." — R. K.]

317

The

Fig. 293i.— Head of the Ibis; taken from a mummy, by M. Olivier.

Most birds perch, and it is easier for them to spread their
wings and take flight when perched on a branch of a tree or
rocky edge than when resting on the level ground. In order
to perch with safety, they embrace the bough closely with
their toes ; and if this required an incessant muscular effort, it
could not be supported for any length of time. A mechanical
contrivance enables the bird to dispense with this even whilst

Fig. 294.— Common Penguin, also called Eazor-billed Auk;
Aptenodytes.

asleep. The flexor muscles of the toes pass over the articula-
tions of the knee and heel in such a way that, whilst they are
flexed they act on the tendons of these muscles, and so flex
the toes. The weight of the body assists in this movement,
which enables the bird to perch without fatigue.

The differences which exist in the form of the feet of birds

318

ZOOLOGY.

Fig. 295.— The Royal Eagle.

Fig. 296.— African Ostrich.

Fig. 297.— Echasse d'Europe ; Stilt, or
European Courser.

THE CLASS BIEDS. 319

have a reference to the mode of life and habits of the animal.
In the cassowary (Fig. 282) and ostrich (Fig. 296), birds as
rapid in running as the horse, the paws are not only robust,
but long, and the feet comparatively small.* In the messenger
(the falco serpentarius, or secretary bird), which pursues
serpents as his food, following them with long strides, this
conformation of the foot is also observed. In the eagle (Fig.
295), falcon, vulture, &c., these organs are not merely robust,
but strong, and the toes are armed with talons, large, hooked,
and sharp, with which they seize, tear, destroy, and carry off

Fig. 298.— Cassowary of New Holland; the Emeu.

their prey. Birds destined to live by the margins of rivers,
and to hunt for worms and fishes in shallow waters, or by
wading, have the limbs (pattes) slender, of great length, and
naked, or without feathers as far as the knee (Fig. 297) ; hence
their name of echassiers, or waders. Finally, in some species
the feet (pattes, digital part of the foot) are palmated, and
thus converted, by an expansion of the integuments, into a
kind of oar. The laxity of this membrane permits of the
full expansion of the foot, as may be seen in ducks (Fig. 300),
swans, and in a great number of aquatic birds.

* In the original it is, " Les pattes sont non seulement robustes, mais
tres-longues, et le pied comparativement petit." But in the word foot
(pied), anatomists include always and in every animal the three regions of
the toes, tarsus, and metatarsus. — K. K.

320

ZOOLOGY.

[Osseous remains of the Moa, or Dinornis. — It is now no longer
doubtful that such remains, which abound in New Zealand, be-
longed to a gigantic bird called Moa by the natives, and Dinornis
by zoologists. It is even conjectured that living specimens existed
in New Zealand not long ago. In this case the bird forms, as it
were, a link between the now living world and the past.

I

Fig. 299.— Skeleton of Dinornis.

Fig. 299a.

In respect of the bones (Fig. 299a) represented in the engrav-
ing, they were discovered by my esteemed Mend, John Stevenson,
Esq., formerly of Auckland, in a marsh or swamp in the
Middle Island, not far from Canterbury, at a depth of three
or four feet from the surface. On being brought to this
country, they were presented to the Geological Museum, in
Jermyn-street, by the publisher of this work. Mr. Stevenson
informs us that numerous similar specimens lay around.

On a careful examination of these remains I found them to be
the right femur and the left tibia of a gigantic moa, whose height
I have endeavoured to estimate, and to compare with that in
the Museum of the College of Surgeons, with the same bones in
the ostrich and emeu. The specimens are incomplete, being
mutilated at their extremities.

THE CLASS BIEDS. 321

Moa, right femur. Inch. Inch.

(Fig. 299a) measures. . . 18^; when complete . 19
Length of the shaft ... 9|

Around the condyles . . . 20f-
Around the upper part of

the bone 28f

Moa, left tibia.

Length of the fragment . . 36
Probable actual length when

entire 40

Circumference around the

condyles 21

Circumference of the shaft 7J

Comparative measurements, showing that this is probably the
tallest bird ever brought to Europe.

/Emu 9

- Ostrich U

) Dinornis giganteus of the museum . . 16

\ Stevenson specimen 19

„.,. /Emu 16

T^. Ostrich 18

length in < Dinornig of the museum 35

I Stevenson moa 40

Metatar- /Emu . . 15

sus, 1 Ostrich 16

length of, j Dinornis of the museum 18f

in the \ Stevenson moa 21*2

The height of the Dinornis of the museum 10ft. 6in.
Height of the Stevenson moa .... 12 0

It is conjectured that birds of a still greater height once existed
in Madagascar. — K. K.]

§ 434. The tactile sensibility is but little developed in
birds, and the form of their wings and feet is also unfavour-
able for its exercise. The taste is more or less obtuse, and
their cartilaginous tongue, without nervous papillae, seems
ill-adapted for taste (Fig. 313). They seem to swallow their
food without tasting it. The sense of smell appears stronger,
but yet not much developed. The nasal fossae are hollowed
out of the base of the upper mandible (Fig. 284), without
communicating with, the sinuses. They have a very vascular
pituitary membrane, and three cartilaginous laminae (cornets)
rolled on themselves, resembling the turbinated bones of
mammals. These laminae seem to be better developed in birds

Y

322

ZOOLOGY.

of prey than in others, leading one to suppose that the sense of
smell is acute in this class of birds; and this has been asserted,
hut experiments and observations of recent zoologists tend to
prove that even in these the prey is detected by the sight, and
not by the smell.* The apparatus of hearing is simpler than
in mammals. The external ear (figured part of the ear) is
wanting, and the apparatus is reduced to an external tube,
a tympanic cavity, and internal ear.f But the organ of sight

Fig. 300.— Scoter Duck ; Black Duck.

seems to be more perfect than in mammals. The eyes are
larger proportionally, and new parts exist. The retina is
thick, and connected by means of a fold passing from the
choroid to the capsule of the lens. It has been called pecten,
and by some is thought to be a dependence ~ of the retina.
The pupil is always round, the cornea large, and the sclerotic

* As early as 1817, I ascertained, by direct observation, that the South
African vulture is solely guided by sight in discovering his prey. — K. K.

t The osfticula auditus are also reduced in number, and much modified. —
R. K.

THE CLASS BIRDS. 323

furnished with osseous plates anteriorly, whose form varies
with the genus and species. Lachrymal glands always exist,
and besides the horizontal eyelids, they have a third, vertical,
moveable, and elastic, which can be drawn completely over the
surface of the eye.

Birds are well known to have a piercing and most distinct
vision at all distances, that is to say, the most complete
adaptation of sight. On what this depends is not clearly
known, some ascribing it to the mobility of the osseous plates
and to the varying form of the lens in this class of animals.*

The nervous system presents the following peculiarities.
The encephalon is less developed than in mammals, but the
cerebral hemispheres (Fig. 301) still
maintain their superiority over the other
parts. The great commissure, called
corpus callosum, is wanting, and there
are no cerebral convolutions. The optic
lobes, or thalami (o), which in mammals
are small, and concealed by the over-
lapping of the hemispheres, are here
exposed and visible without dissection.
They are proportionally much larger, and
instead of being solid, are hollow, like
the cerebral lobes. The cerebellum (v) Fi 301 _Brajn Of
is grooved transversely by parallel and the Ostrich,

converging lines ; it is almost wholly
formed by the median portion ; this in mammals is small
compared with the hemispheres or lateral portions, which
remain rudimentary, as it were, in birds, especially in bad
flyers. The annular protuberance, or pons of Yarolius, is
wanting in birds, as well as in reptiles and fishes. Finally,
the medulla spinalis (e) is generally very long, and has two
swellings in its course, corresponding to the going off of the
nerves of the wings and limbs or feet. The former is the
stronger in birds of powerful flight, and vice versa.

§ 435. The food of birds is very varied : grains, insects,
fishes, flesh, fresh or putrid. They use the feet sometimes as
instruments of prehension, but the bill is always the prin-
cipal organ employed for this purpose ; thus its nature varies
with the food, and it becomes an important character in clas-
sification. A horny covering, solid, and more or less hard,

* The highly-developed anmilus albus seems connected with this adaptive
power.— See Trans. R. S. ofEdin., 1827.— K. K.
Y2

324

ZOOLOGY.

covers the osseous bill externally, converting it into a sort of
cutting and tearing instrument ; but the bird never has any
true teeth : hence there is no mastication, properly so called.
In birds which live on flesh and tear their prey — the falcons
(Fig. 303), the eagles (Fig. 295), and the vultures (Fig. 305)
— the upper mandible is short, strong, hooked, and terminated
by a sharp point ; it is occasionally serrated, and the more
or less sanguinary character of the bird may be judged of by

Fig. 302— The Kite.

Fig. 303.— The Falcon.

these structures. Thus the falcon (Fig. 303), which has all
these characters of the bill in the highest perfection, is the
boldest of all birds of prey ; whilst the kite and vulture, in
which the bill is softer, less hooked, and not serrated, are
cowardly ; the vulture chiefly living on dead or dying animals.
Sea birds which live on fish have the
bill long and hooked (Fig. 304), but
much longer and softer than in the
true birds of prey already spoken of.
In others, which search for small fishes
and reptiles which may be easily swal-
lowed, the bill becomes still more
elongated, resembling a pair of pincers.
Such we find in the kingfishers (Fig.
310) and the cigogne a sac (adjutant),
(Fig. 306). Birds which live on insects
(insectivorous), worms, grains, and
fruits, have nothing of the kind. In
the first, the bill is very slender, and but
slightly curved, or even straight, and much elongated (Fig.
307) ; but if they take small insects on the wing, then their
bill is short and broad and widely cleft, as in swallows, goat-
suckers (Fig. 308), &c. The granivorous have the bill short,

Fig. 304.— The Fulmar
Petrel.

THE CLASS BIRDS.

325

thick, arched above, or conical, and generally straight (Fig.
309). The pelicans present a remarkable modification of the
bill; between the two branches of the lower jaw there is a

Fig. 305.— The Griffon Vulture.
(Vultur fulvus).

Fig. 306.— Pouched Crane, or
Adjutant-bird.

wide cutaneous expansion or bag, in which they store their
food (fishes), to disgorge it afterwards, and to feed on it at
their leisure.

Fig. 307.— Bee-Catcher;
Merops.

Fig. 308.— Goat-sucker.
(Caprhnulgus.)

But some birds present singularities in the form of the bill,
the uses of which are not understood. Such for example is
the bill of the rhinoceros hornbill, or calao (Fig. 312).

326

§ 436. The tongue in some birds becomes an instrument
of prehension, and is modified accordingly. The lingual bones
(h, Fig». 313) are prolonged backwards behind the head, and

Fig. 309.— The Sparrow.

Fig. 310.— Kingfisher.

these prolongations give attachment to muscles (m), found
anteriorly to the lower jaw. When these muscles contract,
they pull forward the hyoid or lingual bones, and these push

Fig. 311.— The Pelican.

the tongue out of the mouth to a considerable distance. This
structure is most remarkable in the woodpecker, arid in others
which dart the tongue rapidly at insects (Fig. 314). In the

THE CLASS BIEDS.

327

parrot, which to a certain degree masticates its food, the
tongue is thick and fleshy ; in birds of prey it is still some-

rig. 312.— Ehinoceros Hornbill.

what large and soft; in most of the granivora (Fig. 313), it
is dry, triangular, and rough towards its base, with small

Fig. 313.*

cartilaginous points ; finally, in certain insectivora its extre-
mity is armed with hooks, and serrated or notched.

* Tongue, glottis, &c. ; I, the tongue ; h, hyoid bones ; m, muscles of the
hyoid; p, pharynx j g, glottis ; t, trachea; e, gullet.

328 ZOOLOGY.

The salivary glands are placed under the tongue, and con-
sist of small masses of little rounded follicles. The saliva is
generally thick and sometimes gluish.

§ 437. There is no velum palati between the mouth and
the pharynx. The gullet (Fig. 315), towards the lower part
of the neck, communicates with an enlarged pouch called the
crop, the walls of which are membranous. In this cavity,
which varies much in different birds, the food remains for a,
time. The crop is most developed in granivorous birds ; it is
also found in birds of prey, but it is wanting in the ostrich
and in most piscivorous birds. Below this enlargement the
gullet contracts, but soon enlarges to form a second dilatation,
called the ventriculus succenturiatus, on the inner surface of
which numerous pores may be seen, leading to the follicles
which secrete a gastric juice. This second stomach is gene-
rally small, but it is larger when the crop is wanting. Finally,
this second stomach leads inferiorly into a third, called the

Tongue.

Fig. 314.— Head of the Woodpecker.

gizzard, in which the chymification seems to be finished.
This varies in capacity and structure. In flesh-eating birds,
the gizzard is thin and membranous ; but in the granivora it
is powerfully muscular, and its inner surface is protected by
an epidermis almost cartilaginous. Its strength is immense.
In the ostrich, the hardest substances are acted on by it, and
it seems to perform the office of a masticatory apparatus.

The intestine following these stomachs is much shorter
than in mammals, but is composed also of two portions. The
first, after forming the first turn, winds in various directions ;
the second differs but little from the first, and is smooth ex-
ternally, but is in general easily distinguished from the first
by two cceca, or elongated cul de sacs, which exist at its com-
mencement. These appendages are very small or absent in
birds of prey, but are large in granivorous birds.

The liver is very large, and fills a great part of the thorax as

THE CLASS BIEDS.

329

well as of the abdomen; these two cavities not being distinct
as in mammals, the diaphragm is rudimentary. This gland,

Gullet.

Ventriculus
Succenturiatus,

Gizzard,

Pancreas
Duodenum

Caecum.

Large Intestine.

Ureter.

Oviduct.

Cloaca.
Anus.

. — Crop.

"" Liver.

— Biliary Vesicle,
r- Biliary Canals.

Fig. 315. — Digestive Apparatus of the Common Fowl.

the liver, is divided into two lobes, nearly equal, and gives
origin to two hepatic canals, which, after uniting, enter the

330 ZOOLOGY.

intestine. Finally, a gall-bladder is almost always present,
which receives from the liver a portion of bile, and pours it
into the intestine by a distinct canal. The pancreas is en-
closed in the first loop of the small intestine ; it is long,
narrow, and more or less divided.

The spleen is small ; the kidneys are large and irregular in
form. They are lodged behind the peritoneum, in little hol-
lows along the upper wall of the pelvis, and, unlike the organ
in mammals, they have no distinct cortical substance. The
ureters, as well as the oviducts, terminate near the anus, in a
dilated part of the intestine called cloaca (Fig. 315) ; there
exists no urinary bladder, and the urine is voided with the
excrements. The urine is composed almost wholly of uric
acid, which is not very soluble, and when dried forms a
whitish mass.

§ 438. The nutrient products of digestion leave the intes-
tine by lymphatic vessels, which terminate in two thoracic
ducts ; these ducts open into the jugular veins an each side of
the base of the neck.

§ 439. The blood of birds is richer in globules than that
of mammals, and these corpuscles, instead of being globular,
are elliptic (Fig. 37). The circulation in birds is complete, as
in mammals, and the anatomical arrangements are the same
(Fig. 47). But the walls of the left ventricle are much
thicker, the auricles have no well marked appendages, and the
right ventricle does not extend to the apex of the heart.
These latter differences are unimportant physiologically. The
aorta at its commencement divides into three large branches
(Fig. 316), of which the first two convey the blood to the
head and neck, wings, and muscles of the chest ; whilst the
third, curving downwards around the right bronchus, becomes
the descending aorta. There exist also some other pecu-
liarities in the mode of distribution of the arteries, such as
the formation of plexuses in various parts of the body. The
venous system terminates in the right auricle by three large
trunks, of which one represents the inferior cava, and the two
others the subclavian veins of mammals, which in birds enter
the auricle without uniting to form a common trunk.

§ 440. The respiratory apparatus presents modifications
more remarkable than those of the circulation. The lungs
communicate with large membranous cells spread throughout
the body, and extending even to the skeleton. Thus the venous
blood in the walls of many organs becomes exposed to the

THE CLASS BIRDS.

331

al

Fig. 316.— Arterial System of a Bird.* The Grebe, Colymbus— a Diver.

* Arteries of the Grebe : a, aorta ; am, one of its large branches : it gives
off the carotid (ac) and subclavian, is ultimately distributed to the muscles
of the chest, and corresponds to the mammary arteries of mammals ; av, one
of the branches of the vertebral artery supplying the muscles of the shoulder;
ee, arterial loops formed by the branches of the external carotid ; al, lingual
artery; t, trachea or windpipe j; ar, renal arteries ; az, ischiatic artery, pro-
ceeding to the lower extremities ; as, sacral artery, forming a c o ntinuation
of the aorta, and giving origin to the inferior mesenteric artery, &c. j cl, the
cloaca.

332

ZOOLOGY.

action of the oxygen contained in these cells, as well as whilst
traversing the pulmonary capillaries.

Trachea.

Pulmonary
Vessels.

Bronchus
"laid open.

Bronchus
" laid open.

Fig. 317.— Lungs of a Bird.

The lungs are not divided into lobes, neither do they fill
the cavity of the thorax. They are, as it were, fixed to the
rihs, and present on their inferior surface several orifices
(Fig. 317) belonging to the bronchial tubes, which traverse
them through and through, and thus convey the air into the
various air cells spread throughout the body. These mem-
branous cavities communicate with each other.

The extension of these cells, and consequently of the air
they contain, bears a ratio to the powers of flight of the bird :
in the eagle they are found in all the bones ; in the penguins
the air is excluded from all, or from nearly'all, the bones. The
air js generally found to extend most into the bones chiefly
used for locomotion, as the femur of the ostrich.

We have already alluded to the power which birds have of
resisting cold, due to the development of the respiratory
function, and to a higher temperature than is found in other
animals.

§ 441. As in mammals, the organ of voice is a dependence
of the respiratory system. The upper larynx is of a very

THE CLASS BIEDS.

333

simple structure, and has but little to do with the formation
of sounds. Its orifice has the form of a fissure (#, Fig. 313) ;
but towards the lower extremity of the trachea is the true
larynx, most remarkable, as might be expected, in singing
birds. This complex apparatus will be best understood by a
reference to Figs. 318 and 319. It may be compared to a
kind of osseous drum, the interior of which is divided inferiorly
by a traversing beam of the same nature, surmounted by a
thin semilunar membrane (<?, Fig. 319). This drum commu-
nicates inferiorly with two apertures of the glottis (rimcp
glottidis), formed by the termination of the bronchi, and

Fig. 318.*

Fig. 319.t

each provided with two lips, or vocal cords ; finally, muscles
whose numbers vary with the species, extend between the
different rings of which these parts are composed, and move
them so as to stretch more or less strongly the membranes
they support. In birds which do not modulate the sounds in
a complex way, the membranous septum is wanting ; in birds
which do not sing, there are no muscles proper to the inferior

* Inferior larynx of the rook : t, trachea ; t', drum formed by the lower
end of the trachea ; I, middle ossiculum of the trachea ; b', first ring of the
bronchi, separated from the third ossiculum of the larynx by a membranous
space ; b, bronchi ; m, proper muscles of the larynx ; these muscles have
been removed on the opposite side ; m', depressor muscles of the trachea.

f Vertical section of the larynx :— t, inferior portion of the trachea divided
as regards the half ; c, semilunar membrane, situated above the point of
reunion of the two glottides, and fixed to the osseous cross-beam (o) j a, little
rim formed by the internal lip of the right glottis ; me, inner surface of the
right bronchus, formed by a tympaniform membrane ; b, portion of the
cavity of the right bronchus, exposed by a section of a part of this membrane.

334 ZOOLOGY.

larynx, and the condition of the glottis (glottides) can only
be modified by those which raise or depress the trachea.

[Note on the tracheal dilatation of the cassowary of New Holland.
— I discovered this remarkable dilatation, or pouch, connected
with the trachea of the cassowary in 1824, and described it in the
Edinburgh Philosophical Journal, 1. x. It appears from what I
learn from Meckel, that Fremery* had, in 1819, seen the opening
in the trachea, but was entirely ignorant of the pouch, or bag,
which he had no doubt cut away unskilfully whilst dissecting
the neck. When in Paris, in 1825, M. Cuvier expressed a wish
to see the trachea and pouch, and his assistant soon found for us
the trachea, but, as in the case of Fremery, the pouch had been
cut away and lost. From the same authority (Meckel) I learn
that this singular structure had been afterwards described by
Hausmann and Wedemeyer.

Fig. 320.— Trachea of the Emu, or Cassowary of New Holland.

The deficiency in the tracheal rings commenced at the 52°,
and extended to the 62°; by this large opening the interior of
the trachea communicated with a pouch not much smaller than
the human head. I at first supposed it to be in part muscular,
but I could not verify this on the dried preparation. The dia-
meter of the opening was about 2^ inches. I believe it is found
in both sexes. The purposes it serves in the economy of the
cassowary have not been discovered ; at the time I made the dis-
covery, I fancied that it might serve as a swimming bladder to
the bird if suddenly placed in difficulty by the inundations for
which Australia was remarkable. But this was, of course, a mere
conjecture. The pouch is situated at the lower part of the neck,
immediately above the sternum, and is thus well placed for a
swimming bladder. It can be filled with air or emptied at the
will of the bird. Meckel examined the bird during life, and
observed that the pouch did not swell when the bird was made
to run, but, on the contrary, evidently became dilated when at
rest.— R. K.]

§ 442. Birds are oviparous, and the young require no

* Spec. Zool. Sistens Obs. Pr. Osteol de Casuaris. Nov. Holl. Tras. ad Ep.
1819.

THE CLASS BIRDS. 335

nourishment from a breast. The period of incubation of the
young in the egg varies with the species, but is nearly the
same in the individuals of a species. For the humming-bird,

Fig. 321.— The Eider (Goose) Duck.

the smallest of the class, the period is twelve days ; for the
canary, it varies from fifteen to eighteen days ; for the domes-
tic fowl, twenty-one days ; twenty-five for the duck ; arid

Fig. 322.— Carolina Duck.

from forty to forty-five for the swan. The heat of the sun
suffices for the incubation of some tropical birds, but in
general it is quite otherwise, and the eggs require to be

336

ZOOLOGY.

placed in a nest, and carefully and sedulously hatched by the
mother.

It is in the construction of the nest that "birds display that

Fig. 323.— China Duck.

wonderful hereditary instinct of which we have already
spoken at considerable length ; a few merely scrape a hole in

Fig. 324. — Egyptian Goose.

THE CLASS BIEDS. 337

the soil, and deposit therein the egg or eggs to be hatched,
but with the greater number it is quite otherwise, and the
species may often be known by the form of the nest (§ 328).
The warm and light substance, called eiderdown, used in
domestic economy, is the soft down which the bird pulls from
its breast to line the nest.

The lay of eggs (ponte) takes place generally once a year,
sometimes twice ; but in a domestic state, the fecundity is
still greater. In the smaller species, the number of eggs
exceeds that of the larger ; the eagle lays but one or two ; the
tomtit and the raven, from fifteen to twenty.

Fig. 325. — Gypaetos, or the Lamb-slaying Vulture ; Bearded Vulture ;
Laemmergeyer.

The constancy with which the parents — sometimes the
female only, sometimes also the male — hatch their eggs ; the
care they take of their young when they appear ; the courage
and intelligence shown by the parent bird in defending the
young, are facts within the observation of all. Nevertheless,
there are some birds, as the cuckoo, which deposit their egg
or eggs in the nests of other birds ; the young cuckoo gra-
dually dislodges his companions from the nest, and occupies
the whole. It afterwards rejoins its parents, which seem to
remain in the neighbourhood for that purpose. Instinct leads
the cuckoo to deposit its eggs in the nest of some insectivorous
bird (that being the food on which its own young requires to
be fed), such as the nests of the linnet, yellow-hammer, black-
bird, &c.

Notwithstanding the strength of the instinct which leads
birds to hatch their eggs, it seems certain that it may be
z

338

ZOOLOGY.

modified by certain circumstances, Ostriches, for example,
sit carefully on their eggs in temperate climates, but leave
them in tropical regions to be incubated by the sun.* It
would seem, also, that several of these large birds unite to lay
their eggs in one nest, taking charge of them alternately.

Fig. 326.— The Owl (Scops Vulgaris) .

Fig. 327.— Bird of Paradise.

§ 443. We have already (§^325) described at length the
migratory instinct of birds, which induces them to migrate
from one region to another at fixed seasons. The cause of
this is explicable in some instances,
but not in others ; for certain
species, it may be affirmed that the
causes of these migrations are
wholly unknown. In some experi-
ments made oil the young of mi-
gratory birds, it appears that the
anxiety to leave comes on when
these are detained in captivity and
plentifully supplied with food.
Upon the whole, atmospheric changes would seem most to
influence migratory birds, and that such changes also modify

* Extremely doubtful.— K. K.

1

Fig. 328.— Sitta; Nut-hatch.

THE CLASS BIEDS.

339

the time of arrival and departure. In each species, however,
the period is fixed, and may he calculated on. Occasionally,
age modifies the time of flight or departure, the old leaving
before the young.

Fig. 329. -The Lark.

§ 444. It is also a remarkable circumstance in the history
of birds, that they can leave their nests for so great distances,

Fig. 331.— Colibri, or Humming Bird.

and yet return without the smallest difficulty or chance of

mistake. Swallows, for example, year after year (for eighteen

years, as proved by Spallanzani) return, young and old, suc-

z 2

340

ZOOLOGY

cessively to the place where they were produced, the young
building their nests in the vicinity of those of their parents.
Spallanzani removed a couple of swallows in a cage from the
nest where they were hatching from Pavia to Milan; on
being let loose they returned in thirteen minutes to their

Fig. 332.— The Parroquet (Ara).

§ 445. The instinct of sociability has also been alluded
to (§ 329, 330, 339), an instinct, however, which prevails
mostly with insectivorous or granivorous birds. Birds of
prey are generally solitary, or live only in pairs.

§ 446. Birds differ also in the manner in which they pro-
cure their food : some search for it by day, others by night,

THE CLASS BIEDS.

341

and some by twilight ; and of these latter, it is sufficiently
remarkable that they are of a sombre colour, with downy
pinions, so that they strike the air without any noise. To

Fig. 333.— Pallas ; Land Grouse of China.

this class belong the owl and goat-suckers, &c ; their habits
and structure are strictly in unison.

Fig. 334.— The Ptarmigan (Lagopus), White Grouse.

§ 447. The species known to naturalists amount to seven
thousand, and their classification is difficult by reason of the
great uniformity of their structure. Their distinguishing
characters, as being in relation with their regime, have been
taken chiefly from the conformation of the bill and legs.

342

ZOOLOGY.

Cuvier, whom we follow, divided them into six orders, —
namely, rapacious birds, passerines, climbers, gallinaceous
birds, waders, and palmipeds.

Fig. 335. — Common Hocco; Curassow; Crax Alector.

§ 448. The rapacious birds, or birds of prey, are recog-
nised by their claws, their robust, short, and powerful bills,
and the strength of their legs. Their aspect denotes their

Fig. 336.— Crowned Pigeon.

fierceness. Of these, some are diurnal, and may be known
by their close plumage, and the lateral direction of their eyes.

THE CLASS BIEDS. 343

These are, the vultures (Fig. 305), the Isemmergeyers (Pig.
325), the falcons, the eagles (Fig. 295), the sparrowhawks,
the Idtes (Fig. 302), the buzzards, &c. The others are noc-
turnal, and constitute the family of the owls, known by their
downy plumage and the anterior direction of their eyes.

§ 449. The order passerine have their legs slender, feeble,
and formed in the usual way, neither armed with claws nor
elongated like stilts, and with a single toe, directed back-
wards. The bill is feeble (Fig. 328), straight, or but little
curved (Figs. 329, 330) ; their wings are sufficiently large ;
and they are all small or of moderate size, and have slight
and light forms.

Some live on insects, others on grain, and others are
omnivorous, and to this order belong all singing birds and
most birds of passage.

Fig. 337.— Apteryx of New Zealand.

The number of the passeres is immense : as specimens we
may mention the blackbird, linnet, swallow, goat-suckers
(Fig. 308), lark (Fig. 329), sparrows, crow, bird of paradise
(Fig. 327), the colibri or humming-bird (Fig. 331), the wren
(Fig. 330), kingfisher (Fig. 310), and the calao (Fig. 312).

§ 450. The climbing birds have, with the regime and the
ordinary organization of the passeres, two toes directed for-
wards and two backwards ; hence the facility with which
they climb in all directions. In this division are arranged the
tucans — remarkable for their enormous bills, the parroquet
(Fig. 332), the cuckoo, the woodpecker (Fig. 291), &c.

344 ZOOLOGY.

§ 451. Gallinaceous birds have the bill moderately en-
larged above, and adapted only for a granivorous regime ;
the wings are short, the body heavy, the legs moderate, and
the toes feeble, but united generally at their base by a small
cutaneous fold. The majority of these birds fly badly ; they
do not build their nests in trees, and they seek for their food
on the soil. This order is composed of two distinct fami-
lies; that of pigeons and that of the gallinaceous birds,
properly so called, comprising the cock, the pheasant, the
peacock, the turkey, the pintado or guinea-fowl, the hocco
(Fig. 335), the partridge, the quail, the ptarmigan (Fig.
334), the grouse, &c.

Fig. 338.— The Dodo (Didus Ineptus).

[In 1598, when the island of Mauritus was first discovered,
this bird, which is now in all probability extinct, abounded
there ; it seems to have been extirpated by the European sailors
who frequented the island. A few specimens were brought to
Europe, and one found its way to Oxford. ;~To the east of the
Mauritius and Bourbon is the little island of Rodriguez (where the
dodo also abounded), on which three species of wingless birds once
existed ; they seem, to have belonged to the same natural family
as the dodo, now extinct. Leguat* was also suppo?ed to have
described the dodo ; also Frangois Coache ; there thus arose the
utmost confusion in respect of the true nature of these birds.
The latest researches on this subject, by Messrs. Strickland and
Melvill, arrange the extinct dodo with the columbidae, or pigeons.
— K. K.]

* A French voyager.

THE CLASS BIEDS.

345

§ 452. The waders (echassiers) are known by their elevated
tarsi, and their legs without feathers inferiorly, a structure
which gives them the appearance of walking on stilts, favour-
able at once to rapid movement and to wading in fordable
waters. Their height is in general elevated, and the length
of their neck is such that, however elevated their legs, they
can collect their food on the ground without stooping. Some
live on herbs, others on aquatic reptiles, others on small

Fig. 339.— The Crane. Fig. 340.— The Common Bittern

of Europe.

fishes. The birds called oiseaux de rivage, frequenting the
banks of lakes and rivers, belong to this division, — such as
the heron, the crane (Fig. 339), the stork (Fig. 306), the
bittern (Fig. 340), the woodcock, the ibis (Fig. 292), the
courser (Fig. 297), the water hen, the flamingo (Fig. 342),
and some other genera which live not near the waters, but
resemble the preceding in their conformation, — such as
the ostrich (Fig. 296), the cassowary (Fig. 282), and the
bustard.

§ 453. Finally, the palmipeds or swimming birds are

346 ZOOLOGY.

characterized by their legs, of moderate length, terminated by
large webbed feet. These serving the purpose of oars, are
formed by the toes being united to each other by an inter-
digifcal membrane of the common integument ; the legs are
placed far back, which is favourable for swimming, but ill
adapted for walking : as examples of this group we may men-
tion the auks (Fig. 294), the penguins, which have the wings

Fig. 341.— The Trumpeter Bird.*

so short that they cannot fly ; the petrels, the albatrosses,
the gulls, and the terns (Fig. 343), which have, on the
contrary, long wings, and a powerful flight ; the pelicans
(Fig. 311), the frigate birds, and the boobies, which are
as well organized for flight as the preceding, and the first still
more completely webbed ; finally, the swans, the geese, and
the ducks (Fig. 300), whose bills are covered with a soft skin
instead of a horny envelope.

* Attempts are now being made to acclimatize this South American bird
in the South of France.

THE CLASS BIEDS.

347

Fig. 342.— The Flamingo.

Fig. 343.— Tern.

348

CLASS OF EEPTILES.

§ 454. The class Reptiles comprises all vertebrate animals
whose respiration is from birth aerienne and incomplete.
They have lungs, like mammals and birds ; but their circula-
tory apparatus is always so arranged that a portion of the
dark blood mingles with the arterial, without having tra-
versed the respiratory organs ; and generally this admixture
takes place in the heart, which has in that case but a single
ventricle communicating with two auricles (§ 108). Finally,
the skin of reptiles is generally or almost always covered with
scales. In their general form they resemble mammals more
than birds; but in this respect they vary. The tortoise (Fig.
345), lizard (Fig. 844), and serpent (Fig. 346), have very
different forms.

Fig. 344. — The Green Lizard ; Lacerta viridis.

Their head is almost always small, and their body very
elongated ; some, as serpents, are entirely without limbs, or
have only vestiges of them (Fig. 272) ; but most of these
animals, the lizard for example, have four limbs, constructed
so as to serve for walking or swimming. Nevertheless, their
limbs, when present, are so short as to allow the body to
touch the soil, and in place of being directed parallel with the
axis of the body, and consequently to move in this direction,
move perpendicularly to their axis, and from side to side.
Hence the name reptile.

§ 455. Their skeleton presents in its structure variations
much greater than what occurs in hot-blooded vertebrate
animals. All its component parts may in their turn be want-
ing, excepting the head and vertebral column ; but the bones
composing it preserve great analogies and homologies with

CLASS OF EEPTILES.

349

the hot-blooded vertebrata, and exhibit analogies with the
other classes.

§ 456. The cranium is always small, and the face elon-
gated. As in birds, the lower jaw is composed of several
distinct pieces, and is articulated as in them with the os
quadratum or tympanic bone. Even this bone is sometimes
suspended to a moveable lever, as in serpent?, by which the
dilatability of the mouth is greatly increased. The upper
jaw is in general immovable, but is so articulated in serpents
as to perform some movements. In several, as in lizards and
tortoises, the bones of the cranium are extended over the tem-
poral spaces like a buckler, thus causing the head to appear
large. Finally, the head is generally not very moveable, and
is articulated with the column by a single condyle with
several faeettes.

Fig. 345. — Common Land Tortoise.

Fig. 346.— Egyptian Aspic.

§ 457. In lizards and crocodiles, and other reptiles formed
after the same way, there are in general but few anomalies ;
the ribs are more numerous than in birds and mammals, and
protect the abdomen as well as the chest. Serpents have
neither sternum nor limbs, and the free extremities of the
ribs seem to be used as organs of locomotion. In the cou-

350 ZOOLOGY.

leuvre (adder or snake) there are more than three hundred
pairs of ribs. The vertebrae also, by their mode of articula-
tion with each other (a kind of ball-and-socket), permit of ex-
tensive movements. But the most remarkable
modification of the skeleton is in the tortoise
and turtle ; the bones form a buckler, within
which the animal may withdraw itself on the
approach of danger. The dorsal osseous plate
is called the carapace ; the ventral, plastron
(Fig. 348). United at the sides, they leave
in front and behind openings for the head and
limbs. This kind of cuirass is only covered
by the skin, which in its turn is protected by
large horny plates : all the muscles and other
soft parts are contained within the cavity thus
/ formed.

§ 458. Notwithstanding the profound
' modifications which the skeleton undergoes

to meet such an organization, we find the same
elements or pieces which constitute the skele-
ton in the other vertebrata merely changed in
form and volume.

When we examine the carapace (dorsal
plate) superiorly, we find it composed of a
i great number of osseous plates, united by

sutures, of which eight occupy the median
line ; sixteen others form on each side a longi-
tudinal row; and twenty-five or twenty-six
surround the whole. We have only to look
at the inner side of the carapace (Fig. 349)
to see that these median pieces are simply
dependencies of the dorsal vertebrae (vd). The
body of each of these bones and the canal for
the spinal marrow may fee seen, with their
ordinary shape, but the upper portion of
the osseous ring has been spread out like a
disc, uniting with the same parts belonging
Fig. 347.— Chal- ^o foe preceding and following vertebrae.

cis : an elon- __, , r , . &, , . , p .

gated Lizard. The dorsal vertebrae become thus immov-
able : each carries a pair of ribs as in
man, but these (c) spread out so as to touch each other
throughout almost their whole length, and to articulate with
each other by means of sutures ; finally, the marginal pieces

CLASS OF BEPTILES,

351

(cs) which articulate with the extremity of the ribs, and
which form in some measure the border of the carapace,
evidently represent the sternal portion of these ribs, which in
mammalia remain cartilaginous, but which in birds are com-
pletely ossified. In some tortoises they remain cartilaginous,
and in almost all these animals several of them are sup-
ported laterally on the edges of the plastron or ventral
plate.

The plastron is formed by the
sternum, which presents an extraor-
dinary development, and extends
from the base of the neck to the
commencement of the tail. The bon es
composing it are nine in number,
arranged in pairs, and so articulated
with each other as to form a great
oval plate. The plastron is some-
times entire and solid throughout its
whole extent, sometimes divided into
three portions, of which the anterior
and posterior are a little moveable ;
at other times it is hollowed out in
the centre like a picture-frame.
Finally, it is fixed on each side to
the carapace by bone or by cartilage.
All the muscles and soft parts, as
well as the organs, are contained within these two plates.

The bones of the shoulder (o, cl, co) articulate with the
vertebral column on the one hand and the sternal on the other.
One of these bones (o) suspending it to the vertebral column is
evidently the scapula ; a second, directed backwards (<?o), cor-
responds to the coracoid bone of birds ; and the third (cl)
represents the clavicle, or at least the acromial process of
the scapula, with which it generally articulates.

The pelvis (b) greatly resembles the osseous girdle formed
by the bones of the shoulder ; it is also composed of three dis-
tinct pairs of bones : the iliac bone, attached to the transverse
processes of the posterior vertebrse of the carapace, a pubis,
and ischium directed towards the plastron, and united to the
corresponding bones of the other side.

§ 459. In other reptiles, the bones of the shoulder more
resemble those of birds. The limbs generally have nothing
remarkable ; sometimes they are truncated at the extremity,

Fig. 348.— The Common
Land Tortoise (Testudo
Grseca), as seen from
below.

352 ZOOLOGY.

as • in the land tortoise ; sometimes they terminate in
slender fingers, as in the lizard ; and at other times the ex-
tremities of the fingers and toes are broadened out, as in the

F g. 349.— Skeleton of the Tortoise.*

gecko (Fig. 350) and being provided with short cutaneous
folds performing the office of suckers, they enable this hideous

* Skeleton of the Tortoise ; the plastron has been removed : vc, cervical
vertebrae ; vd, dorsal vertebrae ; c, ribs ; cs, sternal ribs, — the marginal
bones of the carapace; o, scapula; cl, collar-bone ; co, coracoid bone; b,
pelvis ; ft the femur ; t> tibia ; pt fibula.

CLASS OF EEPTILES.

353

animal to creep along the smoothest walls, and even along the
ceiling.

There are also reptiles which have the fingers capable of
being opposed to each other as in the hand of man : in the

Fig. 350.— The Gecko of the Walls.

chameleon (Fig. 351) they are arranged into two packets, en-
abling them to hold on to the branch ; they have also a pre-
hensile tail, and thus they are in fact climbing animals.
Finally, in other reptiles more formed for an aquatic life,

Fig. 351. — The Common Chameleon.

the feet and hands are formed like oars : the turtle (Fig. 52)
is the only reptile which at present offers us this kind of
structure : but in remote epochs of the geological history of
the globe, our seas were peopled with large animals with

354 ZOOLOGY.

swimming paws resembling oars, and having many points of
resemblance with the reptiles and serpents of the present day.
Modern anatomists have called them ichthyosauri (Fig. 353)
and plesiosauri (Fig. 354) ; and their fossil skeletons have
been found entire.

Fig. 352.— The Turtle (Testudo Caretta). Loggerhead Turtle.

Winged reptiles also exist. The dragons (Fig. 355), ani-
mals resembling lizards, have a large fold of skin placed along
the flanks, resembling the wings of the bat, but are supported
only by the first six false ribs extended horizontally in a

Fig. 353.— Ichthyosaurus ; a fossil animal.

straight line. It uses this merely as a parachute in dropping
from branch to branch ; it inhabits India : thus realizing to
a certain point the flying lizards or serpents of which some
writers have spoken. But the dragons of naturalists attack
only insects.

During the epochs of the great saurians on the earth, there

CLASS OF EEPTILES.

355

existed a flying reptile still more singular than the dragon.
It has been called the pterodactyle ; it was a saurian, made
somewhat like a bat; it could walk or fly, but the little
finger of the hand was thrice as long as the trunk, and
no doubt supported folds of integuments resembling wings
(Pig. 356).

Fig. 354. — Plesiosaurus j a fossil animal.

§ 460. Beptiles are less quick in their movements than
birds or mammals, nor can they sustain their movements so
well, probably owing to a less energetic respiration. The
muscles receive less blood, and are paler; but they may be ex-
cited long after death by a variety of stimulants. The tail of
a lizard detached from the body, has been seen to move for

Fig. 355.— The Dragon.

several hours ; and the turtle, dead in appearance for several
days, may still be made to move its limbs. The mutual de-
pendence between the nervous and muscular systems seems
not to be so intimate as in mammals.

§ 461. The brain is small, smooth, and without circum-
volutions (Fig. 357). The hemispheres are hollow, and there
A A 2

356 ZOOLOGY.

is no striated body. Olfactory globules of considerable size are
situated at the origin of the first pair of nerves. The optic
lobes are in general large, situated behind, and on the same
plane as the hemispheres ; but the little brain (cerebellum) is
small, and it sends no prolongations across the medulla, so as

Fig. 356.— Pterodactyle ; a fossil or extinct animal.*

to form a sort of ring, as in mammals. The spinal marrow,
compared to the brain, is large ; so also the nerves, as com-
pared to the cerebro-spinal axis, are larger than in the superior
classes of animals.

§ 462. The tactile sensibility is but little de-
veloped, the skin being generally protected by
horny scales ; what we call tortoisesheli is merely
the horny plates covering the carapace of the turtle
(Fig. 352), the testudo caretta. The epidermis is
frequently renewed, falling sometimes in portions or
plates, and sometimes cast off entire, as in serpents.
Fig 357 Serpents throw off the epidermic covering several

' times a year.

There is but little remarkable in the eyes of reptiles, but
upon the whole they resemble the eyes of birds; &pecten

* The black part indicates the presumed contour of the skin.

CLASS OF REPTILES.

357

Fig. 358.

is but rarely found. Some have three eyelids, in others
they are wholly wanting, as in the serpent ; to this may be
ascribed its fixed look.

The auditory apparatus is much less complete than in
mammals, or even in birds. The external ear is almost always
completely wanting; there is no
auditory canal, and the drum of the
ear is on a level with the outer
surface of the head; the tympanic
cavity is imperfectly formed, and
seems to be a sort of dependence of
the pharynx. The bones of the
ear most frequently are wanting, and the cochlea is often
rudimentary ; the organs of smell are but little developed ;
the tongue is sometimes thick and fleshy, but generally thin,
dry, and protractile ; in serpents (Fig. 358) and lizards it is
bifid : in the chameleon the tongue becomes an instrument of
prehension, for it can be darted from the mouth to the distance
of several inches, and thus flies and other small insects are
caught by means of a viscous ball which terminates it.

§ 463. Few reptiles live entirely on vegetable food ; they
are almost all carnivorous, and pursue a living prey, which
they swallow entire. The mouth is almost always large in

Fig. 359. — Head of the Crotalus, or American
Eattlesnake.

the cleft, and is so dilatable in serpents as to enable them to
swallow animals having a larger diameter than themselves.
The two branches of the lower jaw (mi, Fig. 359) are united
only by ligament, and the tympanic bone (t), and the
mastoid bone (ma), by means of which the lower jaw is
articulated to the cranium, are both moveable, and thus the

358 ZOOLOGY.

jaws admit of very great dilatation ; moreover, the branches
of the upper jaw (m) are attached to the intermaxillary bones
also by ligaments, and even the palatine arches partake of
the movement. Their teeth are intended only to seize their
prey, and after swallowing it they remain long in a state of
torpidity.

§ 464. Many serpents, such as the viper, the cobra, the
rattlesnake, and the trigonocephalus or brown viper of Caro-
lina, possess a dangerous venomous apparatus of an alarming
character. Certain glands, analogous to the salivary, secrete
this poison (Fig. 360) ; they are placed under the temporal
muscles, so as to be compressed by them when in action. They
communicate by a canal with a fang or poisoned tooth on either
side ; this is either grooved or perforated by a canal, the exit
of which is not at the point, but a little higher up, so as not
to interfere with the action of the point of the tooth. When

Fig. 360.*

the animal bites, the venom is by this means transfused into
the bottom of the wound. These teeth are fixed, but the
bones to which they are attached are moveable ; when not in
use they lie horizontally, with the palate,, encased in a sort of
sheath of mucous membrane. The poisonltself is neither acrid
nor burning to the taste, and it is harmless when swallowed ;
its terrible effects are felt only when mingled with the blood
in a wound, and they vary with the condition of the animal.
On some animals the poison of the viper has no effect, as on
leeches, slugs, the common snake, and the civet ; whilst it

* Poison apparatus in the Kattlesnake : — v, poison gland, with its duct
leading to the large poison fang (c) ; m, elevator muscles of the jaw, which
partly cover the gland, and may compress it; s, salivary glands on the edge
of the jaws ; n, the nostril, under which is the little cavity distinguishing
these serpents and the trigonocephali from vipers.

CLASS OF REPTILES. 359

kills with the greatest rapidity all hot-blooded animals, the
lizard, and the viper itself. A grain of the poison of the viper
will kill a sparrow, but it will require six times as much to
kill a pigeon. As the poison acts through the circulation,
the most rapid means must be adopted to prevent absorption,
such as washing with water and strong spirits, a ligature
round the part bitten, and, if possible, its excision. Ammonia
has been much celebrated as an antidote, but it cannot be
depended on. The Indians of South America consider as a
powerful antidote a plant called guaco, or micania guaco;
they assert not only that the application of the leaves of this
plant to the wound prevents all dangerous effects, but that
the inoculation of the juice of the plant will prevent such
bites having any bad effects. Humboldt thinks that there
may be something in the odour of the plant which may pre-
vent the serpent from biting the person. The serpents with
fangs called moveable are the most dangerous; the fangs are not
in fact moveable, but attached to very small maxillary bones,
which are so. In general you find one fang fixed in either
side, with several others of different stages of growth, ready
to replace them when lost, which probably happens at regular
periods. The poisoned fangs are shed by a process analogous
to what takes place in the teeth of fishes. In the viper,
rattlesnake, cobra, and several others, the upper maxillary
bones carry poison fangs only ; and thus between them and the
common snake there is this marked difference, that the maxil-
lary and palatine bones in the upper jaw carry each a row of
teeth, giving an appearance of four rows to them, whilst in
the true poisonous serpents just mentioned we find only two
rows, the palatine only ; but in the venomous water snakes,
and in many others, the superior maxillary bones carry
simple teeth as well as the poisonous fangs. Some reptiles
have no teeth, such as the tortoise and turtle, a horny layer
like the bills of birds supplying- their place.

§ 465. There is never any pendulous palate, and in most
the pharynx is not distinct from the mouth, nor the gullet
from the stomach. The intestines are short, and have no
caecum ; the large intestine differs but little from the small,
and terminates in a cloaca, as in birds ; they have lymphatic
and lacteal vessels.

§ 466. We have already remarked that their blood is not
rich in globules, and that these are large and elliptic. The
disposition of the circulatory apparatus varies (§ 108), but,

360

ZOOLOGY.

as we have said, there is always a direct communication
between the vascular system carrying red blood and that
carrying dark blood, and thus the organs receive a fluid im-
perfectly acted on by respiration. The heart is almost always
composed of two auricles (Fig. 361), opening into a single
ventricle. The arterial blood coming from the lungs, re-
ceived into the left auricle, and the venous blood coming from
different parts of the body and collected in the right auricle,
are both poured into the single ventricle ; in this they are
mingled together. A portion of this mixture returns by
the aorta into the different organs it is intended to nourish,
whilst another part proceeds to the lungs by vessels which
spring immediately from the common ventricle or from the
aorta itself. In crocodiles, the heart (Fig. 362) more resem-

Pulmonary Artery. ,^

Pulmonary Vein,
Eight Auricle

Vena Cava,
Left Arch of the Aorta...

Eight Aorta.

»* Pulmonary Artery.
^Pulmonary Vein.

Left Auricle.
Single Ventricle.

Ventral Aorta.

Fig. 361.— Heart of the Turtle.

bles that of birds and mammals, having a septum separating
the right ventricle from the left ; but a peculiar disposition of
the arteries causes the mixture of the dark and red blood to
take place at some, distance from the heart, and thus the pos-
terior half of the body receives blood imperfectly arterialized.
In fact the right ventricle, instead of sending off one artery,
the pulmonary, sends off two, one of which winding behind the
heart, unites with the descending aorta, but not until all the
vessels have been given off which go to the head and fore-
part of the body. With regard to the distribution of the
arteries in reptiles, we shall limit ourselves to the remark,
that there exist two or more aortic arches, bending to the
right and left, and reuniting to form a single trunk (Fig. 5 1).

CLASS OF EEPTILES.

361

§ 467. Respiration is not active in reptiles ; they consume
but little oxygen, and can remain alive for a long time without
air ; but this activity differs according to the temperature of
the season. The lungs are composed of large cells, and in
consequence are not very vascular. The tortoise and turtle
swallow the air, as it were, the ribs
being immovable; there is no ao c c a

natural division between the chest
and the abdomen, and respiration
is not regular ; in serpents one lung
is rudimentary (Fig. 363).

§ 468. All reptiles are cold-
blooded animals, and the tem-
perature of their bodies rises and
falls with that of the surrounding
medium . A heat of from 40° to 50°
(Centigrade scale) is quickly fatal
to most of them, and the effects of
cold are well known, for during
winter most reptiles eat no food, and
do not even digest what happens
to be in their stomachs ; the respiration becomes slower, and
their whole state resembles hybernation.

§ 469. Like birds, they lay eggs, and their young do not
suckle ; they have no mamma? ; but there is this peculiarity,
which also happens in some fishes, that in some the young are
hatched before being born, as in the viper ; and such animals
are called ovoviviparous.

The young reptile, on quitting the egg presents nothing
anormal ; it resembles its parent in its mode of respiration,
general structure of the body, and external form.

§ 470. Reptiles generally abandon their eggs when laid,
and the young are developed by the heat of the external
atmosphere; but there is one remarkable exception in the
great Indian serpent, called python, which hatches its eggs,
during which period its own temperature will rise to 40°.

Fig. 362.*

* Heart and large vessels of the Crocodile :— -v, v, veins which bring back
blood from different parts of the body to the right auricle (od) ; vt, the two
ventricles, internally separated by a partition ; ap, the two pulmonary
arteries proceeding from the right ventricle to the lungs ; a, a vessel pro-
ceeding from the same ventricle to the descending aorta ; vp, pulmonary
veins carrying the arterial blood from the lungs to the left auricle (og), from
whence it passes into the left ventricle, and tnus enters the aorta (ao) and
into the two arteries (c c) which proceed to the head, &c.

362

ZOOLOGY.

Fig. 363.— Anatomy of the Coluber (Common Snake) .*•

* I, tongue and glottis; oe, gullet, cut across at OB to show the heart,
&c., in aitu; i, the stomach; i', the intestine; cl, cloaca; an, anus;./, the
liver; o, the ovarium; o', the ova or eggs; t, windpipe; p, principal lung,
p't little lung ; vt, ventricle ; c, left auricle ; <?', right auricle ; a, left aorta ;
ad, Tight aorta ; a', ventral aorta ; ac, carotid arteries ; v, superior cava ;
vc, inferior cava ; vp, pulmonary vein.

CLASS OF EEPTILES.

363

Eeptiles are divided into three orders : chelonian, saurian,
and ophidian.

The chelonian (tortoise and turtle) have four limbs ; the
skin covered with large scales ; the mouth without teeth ;

Fig. 364.— The Agama ; a kind of Lizard.

the jaws provided with a horny bill or covering ; the ribs
immovable, and in them we find the horny dorsal and ven-
tral plates called carapace and plastron, already described.

Fig. 365.— Crotalus, or Eattlesnake.

The saurian or lizard-shaped reptiles, and the ophidians or
serpents, have the ribs and dorsal vertebrae moveable ; a scaly
skin ; and teeth. The two orders run into each other, but
it is generally agreed on to call those with limbs saurian, and

364 ZOOLOGY.

those without, ophidian: as ophidian may be cited the viper,
rattlesnake (Fig. 365), cobra (Fig. 346), as venomous; and
as harmless snakes, the common snake or coluber, the boa,*

Fig. 366.— The Crocodile.

and python. The order saurians comprises crocodiles (Fig.
366), lizards, chameleons (Fig. 351), geckos (Fig. 350), the
agama (Fig. 364), the iguana, &c.

CLASS OF BATRACHIANS.

§ 471. The batrachia or amphibia were long confounded
with the reptilia ; when young they breathe by branchiae or
gills, and resemble fishes in the general conformation of the
body ; but they change their forms and acquire lungs before
becoming adult.

Like fishes and reptiles, they are cold-blooded animals,
their circulation is incomplete, and their respiration com-
paratively inactive. The skin is naked or unarmed, the
skeleton very incomplete, and the heart is composed of a
single ventricle and two auricles.

In their external form they vary considerably, some resem-
bling lizards, and even serpents, but generally the body is
flat, short, and thick, without a tail, with well-developed
limbs.

§ 472. In their mode of development they resemble
fishes ; whilst in the egg, the young animal is not surrounded
by the membrane called amnion, and which is always present
in the three preceding classes; neither have they an allantois,
which plays an important part in the economy of tbe chick

* Travellers are cautioned not to be misled by the names given to serpents
by naturalists. The boa fasciata of Schneider is a most venomous and
dangerous snake.-— K. K.

CLASS OF BATBACHIANS.

365

and of the young of reptiles during incubation ; at birth, they
strongly resemble fishes.

Fig. 367.— The Toad.

The young batrachia are known by the name of tadpoles
(tetards), and are formed for an aquatic life: at birth they have

Fig 368.— Tadpole of the Frog.

a tail, but no feet ; gills projecting externally (b b, Fig. 368),
and their skeleton is cartilaginous.

366

ZOOLOGY.

These projecting gills or branchiae in some continue through-
out life, as in the proteus, axolotl (Fig. 369), and siren.
But in most batrachia these branchiae soon wither away and
disappear, although the aquatic life continues, for the tadpole
has internal branchiae, like fishes, as well as external (Fig.
370) ; these fixed or internal branchiae in the tadpole are

Fig. 369.— The Axolotl j a Mexican Lizard.

attached under the neck to cartilaginous arches belonging to
the hjoid bones, and are protected by the skin ; the water
reaches them by the cavity of the mouth, and escapes by one
or two orifices situated under the neck. In the tadpole of the
frog, the hind feet appear first, and they become of some
length before the fore feet are visible; these appear later

Fig. 370.

Fig. 371.

Fig. 372. Fig. 373. Fig. 374.

Figs. 370— 374.— Metamorphoses of the Tadpole of the Frog.

(Fig. 372). In the salamanders it is the opposite ; finally,
in the siren the hind legs never appear. The tail of the
tadpole continues to grow in the salamander and proteus
with the rest of the body ; but in frogs and in many others

CLASS OF BATBACHIANS.

367

the tail wastes away and disappears (Figs. 373, 374). About
the same time the lungs appear, and begin to perform their,
functions, so that at this period the tadpole is strictly an
amphibious animal ; but although this strictly amphibious
state continues in some, in general it does not; the gills
disappear, and in the adult there remain no traces of such an
apparatus.

3 a ap av c ab 2 vb

Fig. 375.— Bloodvessels of the Tadpole of the Frog.*

The circulatory apparatus also undergoes important meta-
morphoses. The heart of the adult batrachian is composed
of two auricles and a ventricle, whence springs a large artery,
bulbous (like that of fishes) at its commencement, and which
soon divides to form the two arches of the aorta; but when
the young animal breathes by branchiae only, the blood ex-
pelled from the ventricle is distributed to the gills (as in
fishes), whence it proceeds, for the greater part, to the dorsal

* o, artery arising from the single ventricle, and dividing into six
branches (ab), which go to the three pairs of branchiae, and ramify there —
they are called branchial arteries ; br, the branchiae, showing the distribu-
tion of the branchial arteries upon them, and carrying the blood to them and
the branchial veins (vb) , bringing back the blood from them after it has been
exposed to the oxygen of the atmosphere contained in the water sent across
the gills : those of the two last pairs of branchiae unite to form on each side a
vessel (c) which, anastomosing in its turn with that of the opposite side, forms
the ventral aorta or dorsal artery (av), which, proceeding backwards, dis-
tributes the blood to the greater part of the body. The branchial veins of
the first pair of branchiae curve forwards, and carry the blood towards the
head (t, t) ; 1, a very fine and anastomotic branch unites the branchial artery
and vein together at the base of the first pair of branchiae, and this enlarging
afterwards, allows the blood to pass between those two vessels without pass-
ing across the gill ; 2, a small anastomotic branch, uniting in the same way
the artery and vein of the second pair of branchiae ; 3, a vessel which, by
uniting with a small branch situated more inwards, connects the artery and
vein of the posterior branchiae ; o, orbitar artery; ap, rudimentary pulmonary
arteries.

ZOOLOGY.

artery, whose branches ramify in the different organs (Fig.
375). We have already seen, that in fishes the blood follows

op

Fig. 376.*

the same course (§ 109), but when the lungs are developed,
the disposition of the vascular apparatus changes ; a direct

brl

* Fig. 376. The same parts as in Fig. 375 in a tadpole, in which the
branchiae begin to lose their importance, and in which a part of the blood
proceeds from the heart to different parts of the body without traversing
these organs. The same letters indicate the same vessels as in the pre-
ceding figure, and it will be remarked that the anastomotic branches (1, 2,

CLASS OF BATKACHIANS.

369

communication is established between the arteries which
carry the blood to the gills and those which receive it from
those organs, so that the blood is no longer obliged to

Fig. 378.— Skeleton of the Frog.

traverse the gills in order to reach the dorsal artery, and
thence to be distributed to the various parts of the body.
The artery (a) which springs from the ventricle, and which

Fig. 379.— Rainette ; Tree Frog.

may at this time be called a branchial artery, becomes then
the origin of the dorsal vessel, and constitutes with it a true
aorta, certain branches of which proceeding to the lungs, thus

3), which in the preceding tadpole were merely capillary, are now large,
and that it is with them rather than with the branchial vessels that the
arteries coming from the heart seem to be continued. The pulmonary
arteries are also much developed. — Fig. 377. The same parts in the perfect
animal, indicated by the same letters ; the vessels which in the tadpole went
to the two branchiae of the second pair, are continued now with the aorta by
the intermedium of the anastomotic branches (2), and thus constitute the
two aortic arches.

B B

370 ZOOLOGY.

develop and establish a pulmonary circulation. Finally, the
branchial vessels are obliterated, and then the circulation takes
place nearly as in other reptiles. The venous blood returning
from all parts of the body, is poured into the ventricle by one
of the auricles, and is therein mingled with the arterial blood
arriving from the lungs, and poured into the ventricle by the
other auricle. This mixture penetrates into the aorta, and
through it proceeds in small quantities to the lungs, and
hence to the other organs of the body.

The lungs of the adult batrachia have but a few incomplete
cells ; they receive the blood from two small branches of the
aorta, these performing the office of a pulmonary artery.
Thus the pulmonary respiration is feeble, but the cutaneous
makes up for it by its activity. When the temperature is low
it is sufficient to maintain lii'e. Frogs breathe by the action

Fig. 380.— Aquatic Salamander (Newt, Eft, or Evvet).

of deglutition, so that to suffocate the frog it is only necessary
to hold its mouth open for a time. This mode of breathing
is necessitated by the incomplete state of the skeleton of
the adult frog; the ribs are wanting, and thus the thorax can
uu longer be dilated, as in mammals, birds, and ordinary rep-
tiles. Finally, the nervous system in the^e animals is but
little developed ; the brain is small, and the cerebellum is
scarcely visible. '•*

§ 473. Though the class batrachia be not numerous, it
has, notwithstanding, been divided into four orders.

The Arioures, which undergo complete metamorphoses, and
which in the adult state have no tail ; these are the frogs,
toads, rainettes, tree frogs, pipas, Surinam toad, &c.

The Urodeles, which preserve the tail, but which in the
adult state have four limbs, but no branchiae : the aquatic
salamanders or tritons, are examples of this order (Fig. 380).

The Perenniata, which preserve the branchiae throughout
life, and which also have lungs : these are the proteus, the

CLASS OF FISHES. 371

axolotl (Pig. 869), the menobranchus, and the siren. Finally,
the Ceciliae, which have no limbs, and strongly resemble
serpents.

Some very singular animals have been lately discovered,
which have branchiae and lungs like the siren, but which
have in place of feet only cylindrical fins, and which so re-
semble fishes in the whole of their organization, that most
zoologists have arranged them in the following class : — these
are the lepidosirens (Fig. 146).

CLASS OF FISHES.

§ 474. The fifth and last class of the primary division of
vertebrate animals comprises the class fishes. The circum-
stance of their being destined to live under water strongly
affects their whole organization, as is most seen in what
regards the apparatus of respiration and circulation ; they
breathe by gills, and never have lungs* at any period of their
lives. Their heart is composed of two cavities, the Auricle
and ventricle, containing only dark blood ; this blood is sent
to the gills, and returns from these after 'being exposed to
the oxygen, to be distributed to the various parts of the
body, no heart being interposed between the gills and the
other organs of the body ; their blood is cold, and their skin
naked, covered only with scales ; they lay eggs, that being
their mode of reproduction ; and finally, their limbs have the
form of fins.

§ 475. They differ considerably in the form of their
bodies, but the outline is generally simple : there is no neck,
properly so called, and the head is large ; their tail is not
distinguishable from the rest of the body. Some have no
fins, but generally we find them present, arranged in pairs
symmetrically at the sides or singly on the back and abdomen
(Fig. 381). Those in pairs represent the limbs of vertebrate
animals. The anterior are called pectoral fins; the inferior,
which vary much ir* position, are called ventral ; the asym-
metrical fins are the dorsal (d), and (a), and caudal (c),

* The swimming bladder seems evidently to form a rudimentary lung. —
E. K.

B B 2

372

ZOOLOGY.

according as they -are placed on the back, under the tail, or at
its extremity. They resemble each other in structure, and
consist almost always of a fold of skin, supported by osseous
or cartilaginous rays, pretty much in the wa}' that the wings
of bats and dragons are supported by the fingers and ribs.

The large openings leading to the gills are placed behind
the head; in breathing, the water passing into the mouth is
driven across the gills and escapes by these openings. Gene-
rally there is but one on each side, and it has a moveable
protecting covering ; finally, there is throughout the whole
length of the body on either side a series of pores, called the
lateral line. The skin is sometimes almost naked, but in
general is covered with scales ; these have occasionally the

form of rude grains, sometimes of very large tubercles or
plates ; but generally they resemble very thin lamella, over-
lapping each other like the tiles of a house, and encased in
folds of the skin. They may be compared to our nails, but
generally they include much more of the calcareous salts.
The colours of fishes astonish by their variety and brilliancy,
resembling gold and silver : these depend on a number of
small polished plates secreted by the skirR

§ 476. The skeleton of fishes is either osseous or cartila-
ginous : in the lamprey it remains almost membranous, and
thus establishes a link between the vertebrata and inverte-
brata.

§ 477. Their bones have no medullary canal, and when
boiled in water they give out no gelatjne. The skeleton is

* The Barbed Mullet (Mullus Barbatus), to show the different fins, &c. :
— p, pectoral fin; v, ventral fin; dl, first dorsal; d2, second dorsal; <?,
caudal; a, anal; o, opening leading to the gills; b, feelers, or barbs of the
lower jaw.

CLASS OF FISHES.

373

composed of a head, trunk, and limbs, with a hyoid apparatus
largely developed, and assisting in respiration.

§ 478. The structure of the head is very complex, and
composed of many bones ; its median portion (Fig. 383)
presents behind a cranial
cavity (c), lodging the
organ of hearing as well
as the brain. About the
middle are the orbital
cavities (or), and ante-
riorly, the cavities belong-
ing to the olfactory appa-
ratus (ri) and a kind of
large prominence formed
by the vomer, and support-
ing the upper jaw (Fig.
384 v). The analogues of
the occipital, temporal,
sphenoidal, parietal , frontal ,
ethmoidal, and vomer may
readily be recognised, but
most of these parts are
composed of several pieces,
the original germs of these
bones, which never unite
in fishes.

Anteriorly, is found the
upper jaw, which is some-
times fixed, but more
usually very moveable ; on
each side are an intermaxil-
lary bone (im) and a maxil-
lary bone (m), which is
moveable on the first.

A chain of small bones
extends on each side from
the anterior angle of the
orbit to the posterior, and
thus completes the orbital
circle. Deeper may be seen on each side a kind of vertical
partition suspended to the cranium, and separating the orbits
and cheeks from the mouth. It is formed by the analogues
of the palatine, pterygoids, tympanics, &c., and articulates

Fig. 382.— Skeleton of the Perch.

374 ZOOLOGY,

with the cranium by two points (on the vomer and temples).
Inferiorly it gives attachment to the lower jaw, posteriorly
it is prolonged so as to form a moveable covering, called the
gill cover. Three bones on each side form the lower jaw,
which articulates by a concave surface with the jugal ap-
paratus, just described; finally, an assemblage of bones is
found at the bottom of the mouth supporting the gills,
and seemingly analogous to the hyoid apparatus (Fig. 384),
extremely developed.

t p io
Fig. 383.— Bones of the Head of the Pike.*

The bone of the tongue (I) is continued backward with a
series of pieces, and articulates on each side with a very long
and very large lateral branch (£), and this by its opposite
extremity is suspended to the lateral partition of the head,
already described. These lateral branches, formed of several
bones, support inferiorly a series of flattened curved rays (r),
which assist with the circular to complete the walls of the
branchial cavities ; these are the radii branchiostegi. Behind
these branches there descend from the median portion of the
hyoid apparatus four pairs of osseous arches (a), which ulti-
mately are attached to the basis of the cranium by means of
some small bones, called superior pharyngeal bones (ph) ;
these arches carry the gills, and for this reason are called
branchial arches. Still further back, at the entrance of the
gullet, are the two inferior pharyngeal bones, so disposed as
to be applied against the superior.

* c, cranium or orbit ; n, nasal fossae ; im, intermaxillary bone ; m, supe-
rior maxillary bone ; t, a kind of lateral partition separating the cheek from
the mouth, and which articulates forward with the vomer by means of the
palatine arches, above with the cranium (c), below with the lower jaw, behind
with the pre-operculum (p), which, in its turn, supports the operculum (op) ;
io, the pre-operculum bone, followed by the sub-operculum.

CLASS OF FISHES.

375

Such generally is the complicated structure of the head of
fishes : anomalies exist, as in the sword-fish and in some
species allied to the tunny; in these the upper jaw is pro-
longed into a powerful weapon, with which they attack the
largest sea animals. Any further comparison with the osseous
head of mammals need not detain us here, for much uncer-
tainty prevails.

ph ar

co ca ab h r b I

Fig. 384.— Head and Eespiratory Apparatus of a Fish.*

§ 479. In the vertebrate column there are hut two distinct
portions, a dorsal and a caudal (Fig. 382). The body of each
vertebra is formed like an hour-glass, with the two extremi-
ties hollowed out into conical cavities which sometimes unite

* Fig. 384. Osseous head of the Perch, partially dissected, so as to show
the interior of the mouth and the hyoid apparatus : — c, cranium ; or, orbit ;
v, vomer, armed Avith teeth; im, upper jaw ; dp, teeth fixed inro the pala-
tine arch; m, lower maxillary; £, lingual bone; b, lateral branches of the
hyoid apparatus ; s, stylet serving to suspend these branches to the inner
surface of the jugal partitions ; r, radii branchiostegi ; a, branchial arches;
ph, superior pbaryngeal bones ; ar, articular surface of the partition already
mentioned ; o to h, osseous girdle supporting the pectoral fin (p) • o and o ,
scapula, formed of two pieces; h, humerus; ab, bones of the fore-arm ; ca,
carpal bones ; co, coracoid bone.

376 ZOOLOGY.

by an opening : the double cavities resulting from the juxta-
position of the two vertebrae are filled with a soft elastic sub-
stance. The osseous ring formed by the processes of the dorsal
part of the column for the protection of the spinal marrow, is
repeated beneath the column in its caudal portion ; it lodges
the great artery of the trunk.

In some the ribs are wanting, in others they are very com-
plete, and surround the trunk ; and in some they are con-
nected anteriorly with a chain of bones representing the
sternum. The ribs, moreover, often carry one or two small
spines, which are directed outwards, and penetrate the flesh.
Similar stylets also sometimes proceed from the bodies of the
vertebrae ; and these are in some very numerous, as in the
herring. Finally, in the median line of the body are found
the interspinal bones (Fig. 386, i) ; these rest on the spinous
processes of the vertebraa, and articulate by the other extre-

Fig. 385. — Common Swordfish (Xiphias Gladius).

mities with the radii of the median fins (r) ; these radii vary
much in different fishes : sometimes they are only ossified at
the base, formed afterwards of a number of small articula-
tions. These last are called soft or articulated radii ; they
always form the caudal fin (Fig. 382), and sometimes there
are no others.

§ 480. The lateral fins, representing the limbs, are ter-
minated by radii similar to the dorsal, and analogous to the
fingers; in the pectoral fin, four or five small flat bones (Fig.
384 ca) represent the carpus, and these are supported by two
flat bones (ab), the radius and the ulna. The osseous girdle
supporting these is composed of a series of three bones, of
which one (h) represents the humerus, a second (o) the sca-
pula, and a third, composed of two pieces, may be called the
coracoid (co). The posterior limb (Fig. 382) is less com-
plex ; the radii of the ventral fin are supported only on a
single bone.

§ 481. In cartilaginous fishes, such as the skate and the
shark, the skeleton somewhat resembles that of the tadpole.

CLASS OF FISHES.

377

The cranium is without sutures, and is composed of a single
piece, but modelled and pierced like the cranium of a common
fish. The upper jaw is formed of pieces analogous to the
palatine bones and to the vomer ; the maxillary and inter-
maxillary bones either do not exist or are merely rudimentary.
The lower jaw is also formed of a single piece on each side,
and the opercular apparatus is wanting. The vertebral column
is often formed of a single tube, pierced on each side for the
passage of the nerves, but not divided into distinct vertebrae ;
and the gelatinous-looking substance acting as a ligament to
connect the vertebrae to each other, often forms a continuous
cord. The arrangement of the bones of the shoulder, pelvis,
and fins, varies. Finally, the hyoid apparatus supporting
the gills is arranged pretty much as in other, fishes, but in
the last of the series, the lampreys, the branchial arches are
wanting. •

Fig. 386.— Dorsal Fin.

§ 482. Most fish swim with great agility, and it is said
that the salmon goes at the rate of twenty-four feet in a
second. They swim by alternate flexions of the tail and
trunk, and the muscles intended to move these form the
greater part of the mass of the body. The lateral fins are
not much used in progression, and seem merely intended to
maintain the equilibrium of the body, or slightly to modify
the direction of its course.

§ 483. A remarkable feature in the organization of some
fish is the swimming bladder, placed in the abdomen under
the dorsal spine, communicating often with the gullet or
stomach by a canal, permitting of the escape of air from its
interior ; but sometimes no such passage exists, and then it
is evident that the air contained in the swimming bladder is
a secretion from a gland situated on its walls. By the move-

378 ZOOLOGY.

ment of the ribs, this air bladder is acted on, so that by the
quantity of air being diminished, the specific gravity of the
fish alters according to circumstances ; but fish swimming
near the bottom have no air bladder — such as the skate, sole,
turbot, and eel; and sometimes this bladder is membranous
and vascular, so as to resemble a lung.

In a small number of fishes, as the flying fish, the pectoral
fins are much extended, so as to permit the animal to leave
the waters and to fly to a considerable distance; and some
by the same means travel on the land, and even climb up
trees.

Whilst speaking of the organs of motion in fishes, we
cannot omit mentioning a singular apparatus which some of
these animals have, by means of which they adhere strongly
to a foreign body : it is a flattened disc covering the top of
the head, composed of cartilaginous plates, moveable, and
directed obliquely backwards (Fig. 387). Fishes of the
genus echeneis are the only ones which have this kind of
organization, and the species found in the Mediterranean
has been long celebrated under the name of remora (Fig.
388). Its natural history has been overloaded with fables,
and the power of suddenly arresting a ship in its course was
ascribed to it. A species closely resembling the preceding is
very common in the waters around the Isle of France, and it
is said that on the coast of Caffraria it is employed in fishing
for other fishes. A line being attached to its tail it is launched
in pursuit of others ; so soon as it becomes attached to them
the fisherman, by means of the string, gains possession of
both.

§ 484. The life of a fish is occupied almost wholly in pro-
viding for its subsistence and escaping its enemies ; its senses
and faculties seem obtuse and limited ; it exercises no known
industry, and seems to be without any remarkable instinct ;
its brain is small, and the organs of sense imperfect. The
brain does not fill the cavity of the cranium, there being
found within it a spongy fatty mass, particularly in the adult
specimen. The lobes composing the brain are placed in a
file, one pair behind another, — namely, the olfactory lobes,
the hemispheres, the optic lobes, and the little brain, and
behind that the lobes belonging to the medulla oblongata.
The sense of touch seems to be exercised only by their lips
and by the feelers surrounding the mouth (Fig. 381 b) ; their
taste must be imperfect, considering the structure of the

CLASS OF FISHES. 379

tongue ; and as the nasal fossae consist of cavities which are
traversed neither by air nor water mixed with air, the power
of smell cannot be acute. The organ of hearing is enclosed
within the cavity of the cranium, and is composed of a ves-
tibule and three semicircular canals, which sounds can only
reach by vibrations of the common integuments and bones of
the cranium. The eyes, it is true, are large, but not very
moveable, the iris is not contractile, and the lens is spherical ;
they have neither eyelids nor lachrymal apparatus. In some
flat fishes — as the sole, plaice, turbot — both eyes are placed on
one side of the head, and this want of symmetry extends to
other parts of the body.

§ 485. Fishes are very voracious : a very few only live
chiefly on vegetables ; and they are indiscriminate as to their
food. Some species have no teeth ; but in most there exist
several rows, as in the shark (Fig. 390) ; we find them,
indeed, attached to several bones with which they unite, for

Fig. 387.— Dorsal fin of Fig. 388.— Kemora ; Sucking Fish,

the Remora.

they have no roots ; they are shed at regular intervals and
replaced by new teeth, and being generally all of one kind
they receive their names from the bones which carry them,
as palatine, vomerine, maxillary, &c. But in different species
they vary very much in form, being sometimes so fine and
thickly set as to resemble the pile of velvet, in others they
are strong robust hooks, rounded tubercles, or sharp cutting
plates.

§ 486. Some, as the lamprey, live by suction, nevertheless
they also have teeth. There is no salivary apparatus, and the
gullet is short, the liver large and soft, and the pancreas is
replaced by the pancreatic caeca surrounding the pylorus;
finally, the position of the extremity of the gut varies much ;
the kidneys are extremely large, extending on both sides of
the vertebral column, and nearly throughout its whole length.

380 ZOOLOGY.

Their excretory ducts terminate in a kind of bladder, the
external orifice of which is situated immediately behind the
anus and the orifice of the reproductory organs.

Digestion seems to be performed rapidly, and the chyle is
absorbed by numerous lymphatic vessels which terminate by
several trunks in the venous system near the heart.

Fig. 389.— The Turbot.

§ 487. The blood of fishes is red, and the globules are
elliptic, and of considerable size (§ 81, Fig. 37 c). The heart
(Fig. 52) is placed under the throat, in a cavity separated
from the abdomen by a kind of diaphragm protected by the
pharyngeal bones, the branchial arches, and the humeral
girdle. It is composed of an auricle and ventricle, from which

Fig. 390— Head of the Shark.

springs the pulmonary artery. This vessel is enlarged into a
contractile bulb at its commencement ; it soon divides into
branches, which proceed to the gills ; and the blood, after
having traversed these organs, returns towards the heart by
another vessel, also passing along the edge of the branchial

CLASS OF FISHES. 381

arches. There these canals send some branches to the neigh-
bouring parts, and reunite to form a large dorsal artery, which
proceeds backwards under the vertebral column, and gives
branches to all parts of the body (Fig. 52). Finally, all the
venous blood does not pass directly to the sinus (auricle)
already mentioned ; that from the intestines and from some
other parts, before returning to the heart, circulates in the
liver by the vena portse.*

Thus it is that the heart of fishes corresponds to the right
or anterior heart of hot-blooded animals, and the blood passes
only once through the heart. The circulation must be slower
than in them ; nevertheless, the pulmonary (branchial) circu-
lation is complete (Fig. 49).

§ 488. Respiration is performed in fishes by means of the
air dissolved in the water, which entering by the mouth is
passed across the gills or branchiae. These are vascular
laminae, supported by the osseous branchial arches already
described. Four branchiae generally exist on each side. In
most cartilaginous fishes there are five, and in the lamprey
seven. In nearly all the osseous fishes these lamellae are
simple, and are fixed only by the base ; but in a small

Fig. 391. — Hippocampus or Sea Horse.

number, such as the hippocampi, commonly called sea-horses
(Fig. 391), they are, on the contrary, ramified, and have the
form of bunches of feathers ; finally, in most cartilaginous
fishes, as in the skate and shark, they are attached by their
external edge to the skin, as well as by their internal to the
branchial arches.

The mechanism of breathing is best observed in the living
fish : the mouth and gill-covers open alternately ; the water
entering by the mouth escapes by the openings of the gills,
the gills themselves having in the meantime been bathed in
it ; whilst this happens, the oxygen is extracted from the
water. In osseous fishes there is generally but one aperture

* As in mammals, birds, &c.— K. K.

382 ZOOLOGY.

of the gills on either side : in those with fixed gills, there are
as many apertures as branchiae. Thus, in the shark (Fig. 392)
there are five pairs of openings, and in the lamprey (Fig. 409)
seven. Hence the nature of the respiratory apparatus may be
known by an inspection of the exterior. Finally, in some fishes
(the lamprey), the water entering by the mouth reaches the
gills through a kind of canal placed under the gullet, and
interposed between the cavity of the mouth and that for the
gills; the arrangement resembles in some measure the trachea
of the higher organized animals.

Fishes do not consume much oxygen ; nevertheless, some
come to the surface from time to time to breathe air, as if
that absorbed by the gills was not sufficient. Some even
swallow it, and convert the oxygen into carbonic acid whilst
passing through the intestines ; the loach of still waters
presents this singular phenomenon. When removed from

Fig. 392.-The Shark.

water into the air, most fishes speedily become asphyxiated,
not from the absence of oxygen, but because the branchial
laminae, no longer floating in water, collapse, and exclude the
access of air ; they also dry up, and become unfit for the
exercise of their functions. The larger the external aperture
of the gills, the speedier does death ensued

The family with labyrinthiform pharyngeals* have recep-
tacles in which they can preserve water, as in reservoirs, to
moisten the branchiae : these receptacles are ^ater-collecting
cells placed above the branchiae ; hence the name of the
family.

These cells (Fig. 393), enclosed under the gill-cover, and
formed by the lamellae of the pharyngeal bones, retain a cer-

* Examples : andbas scandens, climbing fish ; osphromenus olfax, the
gourami.— E. K.

CLASS OF FISHES. 383

tain quantity of water, and thus allow the animal to live a
long time in the air. They leave the rivers and stagnant
waters in which they live to traverse tracts of land, and some
even are enabled to climb trees, as the anabas. They are
natives of the Indies, China, and the Moluccas; and one spe-
cies, the gourami, much esteemed, has been acclimated in the
ponds of the Isle of France and Cayenne.

Fig. 393. — Respiratory Apparatus of the Anabas,
or Climbing Fish.

§ 489. A remarkable production of fishes is that of elec-
tricity, and the power it gives them of killing their prey by
an electric shock. The torpedo, the silurus or malapterurus,
and a species of gymnotus have this power ; and what is very
remarkable is, that the electric organ presents a different
conformation in each.

The gymnotus, or electric eel of Surinam (Fig. 394), pos-
sesses the power in the highest degree; it resembles an eel,
but it has no fins towards the extremity of the tail, and it
has no distinctly visible scales. It attains sometimes six feet
in length, and the skin is covered with a gluey matter. It
is met with in vast numbers in the rivulets and stagnant
waters of the immense plains of South America. The elec-
tric shocks, which it discharges at will, are sufficiently strong
to kill men and horses ; and being transmissible through
water, the gymnotus does not require to touch its prey. At
first the electric discharges are feeble, but when roused they
become terrible; but by this effort it becomes exhausted,
and requires repose before it can renew the attack ; this is
the moment its captors avail themselves of to seize it.

384

ZOOLOGY.

Wild horses are driven into the waters inhabited by these
fishes, and on these the gyranoti expend the first shocks;
being thus exhausted, they are easily taken by the net or
harpoon. The electric organs of the gymnotus are arranged

Fig. 394.— The Gymnotus Electricus ; Electric Eel of Surinam.

along the back and tail in four longitudinal fasciculi, com-
posed of a great number of parallel membraniform plates,
which are nearly horizontal, and united by an infinity of other
still smaller plates,* placed vertically
across; these small prismatic and trans-
verse cells formed by the reunion of these
laminae are filled with a gelatinous matter,
and the apparatus receives numerous very
large nerves.

The torpedo (Fig. 395), is a cartilaginous
fish, resembling the skate. Its body is
smooth, arid represents a disc nearly cir-
cular, the anterior e4ge of which is formed
by two prolongations of the muzzle, which
on each side proceed to unite with the pec-
toral fins, and leave between these organs,
the head, and the branchiae, an oval space,
in which is lodged the electric apparatus of
the fish. This apparatus (Fig. 396) is com-
posed of a number of vertical membranous
tubes closely packed like honeycomb, and subdivided by hori-
zontal partitions filled with mucositien, and animated by several

* I have counted 240 of these plates in the inch.— K. K.

Fig. 395.— The Com-
mon Torpedo.

CLASS OF FISHES.

385

very large branches of the pneumogastric nerve. In these
singular organs is produced the electricity, which has now been
proved to resemble in every respect common electricity. These
animals are less powerful than the gymnotus. By experiment,
it has been ascertained that this property depends on the
posterior lobe of the encephalon, and that by destroying this
lobe, or cutting the nerves proceeding from it, the faculty is
lost. They are found in the seas on the coast of La Vendee
and Provence.*

Fig. 396.— Electric Apparatus of the Torpedo.f

* The Romans were well acquainted with the electric properties of the
Torpedo, and used them for the cure of paralysis. — R. K.
f o, the brain ; me, spinal marrow ; o, eye and optic nerve ; e, electric
C C

386 ZOOLOGY.

Finally, the silurus electricus or malapterarus (Fig. 397), is
a native of the Nile and the Senegal : its length varies from
a foot to fifteen inches, and its electric properties seem to
reside in a particular space, situated between the skin of the
flanks and the muscles, resembling a leafed cellular tissue.
The Arabs call it the raasch, which signifies thunder.

§ 490. Fishes multiply by means of eggs, and a single
spawning in some produces hundreds of thousands. In
general they have only a mucilaginous protecting envelope,
and they are hatched after spawning without any care on the
part of the parent. But some are ovoviviparous. However this
may be, they are all abandoned by their parents, and many
perish. It is probably owing to the circumstances connected
with the birth, that fishes are found in vast troops, called by
the fishermen banes. These reunions can scarcely be called
societies, and they probably follow each other from a tendency
to imitation.

Fig. 397. — Electric Malapterurus of Africa.

§ 491. However this may be, these animals unite in vast
troops to ascend rivers or to change their habitat. Some
lead a sedentary life, remaining always in the same locality ;
others are constantly wandering, and some perform distant
voyages. At fixed periods of the year they assemble in vast
numbers from regions which, if not distant, are at least un-
known. This is the case with the herring, and the same may
be said of the salmon. The herrings deposit their eggs near
the coast, and the young retire, in all probability, merely into
deeper waters. The idea of their travelling to and from the
Arctic Seas seems quite a fable. They appear on the coast in
winter and in early spring, and again at midsummer and
during the autumn. Their numbers when they first appear
seem incredible ; but they are capricious, and will abandon

organs ; np, pneumogastric nerves proceeding to the electric organs ; nl, a
branch of the preceding forming the lateral nerve; n, spinal nerves.

CLASS OF FISHES. 387

certain waters for a long period. From the middle of October
to the end of the year they abound in the part of the sea called
La Manche (the English Channel), and principally in the
Straits of Dover, as far as the mouth of the Seine. In July
and August they are generally found in the open sea, at a
distance from the coast, and the spawn has been found at
every season of the year. After spawning, they are poor and
of little value. Sixty thousand eggs have been found in a
single female of a medium size. In conclusion, but little is
known of the natural history of the young of these fishes.^

§ 492. The sardine, mackerel, herring, and anchovy are
fish of passage, or migratory, which periodically visit our
shores and give rise to important fisheries. The salmon is
also equally remarkable for its journeys or voyages. It in-
habits all the Arctic Seas, and each spring it enters the rivers
in vast troops, to ascend them even to their sources. In
these emigrations the salmon follow a regular order, forming
two long files, reunited in front, conducted by the largest
female, which precedes, whilst the small males form the rear-
guard. These troops swim in general with much noise,
in the middle of rivers, and near the surface of the water if
the temperature be mild, but nearer the bottom if the heat be
great. In. general, salmon advance slowly, sporting as they
proceed : but if danger appears to threaten them, the rapidity
of their course becomes such that the eye can scarcely follow
them. If a dyke or cascade opposes their progress, they make
the greatest efforts to overcome it. Resting on some rock,
and extending the body suddenly and with violence, after
being curved, they spring out of the water, leaping occa-

* The herring fishery was formerly, especially with the Dutch, a branch of
industry of great national importance ; and in the two provinces of Holland
Proper and West Friesland, two thousand vessels and more than eight
hundred thousand people were engaged in this fishery. Although much
diminished in importance everywhere, the various ports between Dunkirk
and the mouth of the Seine still employ from three to four hundred vessels
and about five thousand seamen in this fishery, and the products have been
valued at nearly four millions of francs.

It is a net fishery, the nets being suspended in the sea like a wall : into
the meshes, which must be of a legal size, the herring enters head foremost
beyond the gill covers, and is thus caught between the gill covers and the
pectoral fin. If intended for salting, it should be done as soon as possible.
By the old Dutch laws, no herring was allowed to be salted after sunset.
The Dutch still maintain their superiority in the curing of herrings.f

t The pilchard, still caught in great numbers on the coast of Cornwall, is a
fish analogous iu its habits to the herring. — K. K,

c c 2

388 ZOOLOGY.

sionally to the height of four or five metres (fifteen feet) in
the air, and so as to fall beyond the obstacle which stops them.
Salmon ascend rivers even to their source, and search in the
small streams and tranquil places a bottom of sand and
gravel adapted for the deposition of their eggs. Then, feeble
and thin by such fatigue, they descend in autumn towards
the mouth of the rivers, in order to pass their winter in the
sea. The eggs are deposited in a trough dug by the female
in the sand; they are afterwards fecundated by the male.
The young salmon grow very rapidly ; and when they are
about a foot long, they leave the rivers to repair to the sea,
which they quit in its turn to again enter the rivers, when
they are about four or five decimetres in length (from sixteen
to twenty inches), that is to say, towards the middle of the
summer that followed their birth. We have already seen
that the swallows, which at the approach of the cold season
emigrate to the south, return annually to the same places.
It appears that salmon have the same instinct. To be assured
of it a naturalist of the name of Deslandes put a copper ring
in the tail of twelve of these fishes, and restored them to
liberty in the river Auzou, in Brittany. Soon afterwards they
all disappeared, but the year following they caught in the
same place five of these salmon ; in the second year three, and
in the year following still three.

[The history of the Scottish salmon, which I have investigated
with much care, differs in many essential points from that given
in the text by my friend, the author. The precise habitat of the
salmon whilst in the ocean is unknown ; but at stated periods it
ascends the rivers even to their sources, in general during the
autumn and early winter months. Under the gravel of these
fresh-water streams it deposits its eggs, which in early spring,
usually about the beginning of May, leave the gravel to pass
into the stream. The period intervening* between their escape
through the gravel to their descent to the ocean as smolts (that
is, young fish covered with silvery scales), has not yet been fully
determined, some viewing it as a year, others only a few weeks.
One thing is certain ; when the ova or eggs of the salmon have
been removed from the salmon artificially and deposited under
the gravel of an artificial pond in October or November, the
young are found to ascend through the gravel in the waters of
the pond in April of the following year, and at that time are
about an inch in length. If detained in the pond they grow but
little ; nevertheless, in the month of May of the year following
their ascent through the gravel they undergo the metamorphosis

CLASS OF FISHES, 389

into smolts, that is, they lose most of their generic characters,
and becoming covered with silvery scales, descend the fresh-
water streams to the ocean. It has been proved, experimentally,
that these smolts, which measure when they leave the pond for
the ocean only four or five inches, return to the rivers, in five or
six weeks, well grown fishes of five or even six pounds weight.
Such is the effect of their residence in the sea even for a few
weeks. But what is remarkable is that all the fry do not leave
the pond at the same time, though of the same size and age. A
full half remain, from causes unknown, and only descend to the
sea the following year. The cause of these anomalies, and even
the residence of the fry for a year in the fresh- water ponds, I am
inclined to ascribe to their being placed in an unnatural position ;
confined and cribbed, and so stunted in their growth and develop-
ment. Thus certain interesting questions in the history of the
salmon still remain unsolved : the first of these is the period
passed in the running stream, its natural habitat for the time
from the moment when it passes through the gravel (in April) to
its descent to the ocean as asmolt : experiments made in artificial
ponds cannot decide a question of this kind. Second, when young
salmon are detained in ponds, a certain number only leave the
ponds after the second year of their residence in such waters ;
what becomes of these ? Third, what is the true nature of the
smolt, first called par, which frequents at all seasons the rivers
from near their sources to the estuaries in which they terminate ;
which so closely resembles the young of the salmon before it
assumes its silvery scales ; which is male and female in nearly
equal numbers, but in which the ova of the female are never
developed, whilst the milt of the male is found developed nearly
at every season of the year. — R. K.]

§ 493. The habits of fishes do not offer many curious
particulars ; nevertheless, reflecting on their importance but
a few years ago in the history of the maritime nations of
Europe, and that in France there are from thirty to forty
thousand seafaring men still engaged in this branch of in-
dustry, extending their voyages to the coasts of Iceland and
Newfoundland in quest of the cod (Fig. 398), a large and
excellent fish abounding on these coasts, though not on ours,
the subject cannot be said to be without interest.

§ 494. Classification. — Fishes form one of the most
numerous classes of the animal kingdom, and are usually
divided into two series, according to the nature of their
skeleton.

The group or sub-class of osseous fishes is by far the most
numerous in genera and species. It is composed of all the

390 ZOOLOGY.

ordinary fishes, and is subdivided into six orders by cha-
racters in general not very important. These orders are —
Acanthopterygii, Malacopterygii abdominales, Malacopterygii
sub-branchiales, JVJalacopterygii apodes, Lophobranchii, and
Plectognathi.

Fig. 398.— Common Cod.

§ 495. The plectognathi differ from all other fishes in the
conformation of their mouth, for in them the upper jaw-bone
is united to the cranium. This family comprises the coffres
(Fig. 399), which have the body covered with a kind of cuirass
with osseous compartments ; the diodon or globe-fish, and
the tetrodon, which by swallowing the air become inflated
like a ball, are examples of this class.

§ 496. The lophobranchii are characterized by the struc-
ture of the gills. These, instead of resembling the teeth of a
comb, divide into little rounded tufts, fixed in pairs along the
branchial arches. The syngnathus and the hippocampus
belong to this family.

Fig. 399.— Trunk Fish (Ostracion).

§ 497. The acanthopterygii comprise all osseous fishes
with the upper jaw moveable and comb-formed branchiae, and
in whom the first fin is supported by osseous and spiniform
rings (Fig. 386). The perch, the mackerel, the tunny (Fig.
400), the sword-fish, and nearly three-fourths of all known
fishes belong to this family.

CLASS OF FISHES.

391

§ 498. The abdominal malacopterygii are distinguished
from the preceding by having the rays of the first dorsal fin
cartilaginous, articulated towards the extremity, and generally
divided into several branches (Fig. 301). This character is
common to it with the two remaining groups of osseous
fishes, and to distinguish them it is necessary to add, that
the ventral fins are situated under the abdomen, behind the
pectoral fins, and not attached to the bones of the shoulder.
To this order belong the carp, the pike (Fig. 402), the
silurus (Fig. 397), the salmon, the herring, the sardine, and
the anchovy.

Fig. 400.— Tunny.

§ 499. The sub-branchiated malacopterygii have the fins
formed in the same manner as in the last ; but their abdominal
fins are placed under the pectorals. This division comprises
the cod (Fig. 398), the whiting, the remora (Fig. 388), and the
family of the pleuronectidse, or flat fish, as the plaice (Fig. 404),
the turbot (Fig. 389), the sole, &c.

Fig. 401.

Fig. 402.— Pike.

§ 500. Finally, the malacopterygii apodes are characterized
by the absence of ventral fins, and of spinous rays in the
dorsal fin. To this family belong the eels, the gymnotus
(Fig. 394), &c.

§ 501. The cartilaginous fishes, or chondropterygii, have
the skeleton cartilaginous, and sometimes almost membranous,
never osseous, the calcareous matter hardening its surface
being deposited in little grains. There is even a resemblance
between it and that of the tadpole. The superior maxil-

392

ZOOLOGY.

lary and intermaxillary bones are rudimentary, and the upper
jaw is formed essentially by the palatine bones. Sometimes
the gills are free at their edge, and sometimes fixed, and this
difference serves as a basis for their division into two groups,
— namely, the chondropterygii with free branchiae, and those
with fixed branchiae ; and these latter are subdivided into two
others, the selaciens and the cyclostomes.

Fig. 403.— The Anchovy.

§ 502. The order of chondropterygii with free gills are
also called sturiones, because they have for their type the
sturgeon (sturio). It is composed of fishes in whose figure
there is nothing irregular (Fig. 405), and which have for the
most part the skin provided with large osseous plates dis-
posed in rows,* and the mouth toothless.

Fig. 404.— The Plaice.

§ 503. The chondropterygii with fix«d gills have a re-
markable common character, which has already been de-
scribed. The gills are fixed at both edges, and instead of
having one opening by which the water escapes, there are
several, — as many openings, in fact, as there are intervals
between the gills. The openings are almost always external,
nevertheless they terminate sometimes in a common canal,

* In other words, a dermoid skeleton. — E. K.

CLASS OF FISHES.

393

by which they transmit the water externally ; finally, car-
tilaginous arches suspended in the flesh are often found op-
posite the external edges of the branchiae. Lastly, these
fishes differ much from each other, and constitute two orders
— the selacian (plagiostomi) and the cyclostomi.

Fig. 405.— The Sturgeon.

§ 504. The first, including the family of the squali, com-
posed of the sharks properly so called, the requin (Fig. 392),
the hammer-headed shark (Fig. 407), the saw-fish, &c. ; and
the family of the skate, in which the torpedo (Fig. 395)
as well as the skate properly so called have a place (Fig. 406).
All these fishes have five branchial openings on each side of
the neck, resembling fissures ; and several have on the upper
part of the head two openings, called blow-holes, by which
the water reaches the gills when the throat is temporarily
filled with their prey. They are most voracious animals,
especially the requin or blue shark (Fig. 392). Some are
oviparous, whilst others lay eggs covered with a hard and
horny case.

Fig. 406.— Skate.

Fig. 407.— Hammer -headed Shark.

§ 505. The order of cyclostomes is characterized by the
singular conformation of the mouth, adapted only for suc-
tion (Fig. 408) ; they are the most imperfect of all the
ordinary vertebrata. Their skeleton is sometimes mem-
branous, as in the ammoccetes or river lampreys, and is always
less complex than in other fishes ; their nervous system is
but little developed, and the gills have the form of small bags.

394

ZOOLOGY.

The lampreys (Fig. 409) constitute the principal type of this

group.

§ 506. A very singular animal, evidently belonging to the
vertebrata, but deficient in many of
their characters, has lately attracted
some attention. It is called the
amphioxus, and is a small marine
animal, sufficiently like a fish, but
which has neither vertebrae properly
so called, nor heart, nor red blood,
nor a distinct brain. Its skeleton is
represented by a cartilaginous stalk,
resembling the cartilaginous cord
preceding the formation of the
vertebral column in the embryo

of the ordinary vertebrata ; the cerebro- spinal axis occupies

its usual place, but presents anteriorly no enlargement which

Fig. 408.— Mouth of the
Lamprey.

Fig. 409.— The Lamprey.

may be compared to a brain ; the circulation is accomplished
by means of vessels whose walls are contractile, and the walls

Fig. 410.— The Gourami.*

* A valuable fish, now being acclimatized in France ; it comes originally
from China and some Asiatic rivers. It was first introduced into the Isle of
France.— E. K.

CLASS OF FISHES.

395

of the pharyngeal cavity take the place of a respiratory appa-
ratus. Most zoologist arrange this degraded vertebral animal

Fig. 411.— The Binny.*

in the class fishes ; but it seems evident to us, that in a natural
classification the amphioxus ought to occupy a particular
division.

Fig. 412.— The Flathead.f

[It formed no part of the plan of the author's excellent work
to follow out any of the great views which the introduction of
the transcendental anatomy into science has forced on the consi-
deration of all observers, and I have therefore not deemed it
necessary to add largely to the few hints given by the author
himself. As in a passage or two of the preceding portions of
the work the author has glanced at a subject of great interest,
namely, the distinctness of species, and even of genera, yet strongly
resembling each other in different regions of the globe, I have
thought that the following brief sketch of the relation of species
to genus might interest the reader : —

"Zoology, to be esteemed a science, must be based on philo-,

* Barbus Binny : Cyprinus Binny. It is extremely common in the Nile,
and very good to eat. Its qualities as an article of food have given rise to the
following Egyptian proverb — " If you know of any better than I am, do not
eat me." — K. K.

t Flathead : from a drawing by Mr. Burchell. It inhabits the waters of
the Great Orange Itiver in South Africa. — E. K.

396 ZOOLOGY.

sophical principles. True, it is a science of observation, and not
of calculation ; it has to deal with living bodies, arid with the
mysterious and hitherto undiscovered principle of life, whose
laws are not to be explained by numbers, however multiplied,
nor by a geometry, however refined. Fluxions avail not here,
nor the integral calculus. Nevertheless, some great minds have
shown that Zoology has its laws, which, despite difficulties almost
innumerable, may be so inquired into as to evolve some truths
of more import to man than at first appears.

"The observation of nature is no doubt the first duty of every
candid observer ; next conies the duty of the inquirer into her
laws, for the mere observance of a fact is of no value whatever,
unless that fact be placed in its relations with all others. Men
had observed, and no doubt observed carefully, long before the
age of Aristotle, but he alone was equal to the production of the
Historia Animalium. He was followed, at a long interval, by
Buffon and Linne' ; last came the immortal Cuvier. The dis-
covery of the true signification of the fossil remains of the organic
world by this illustrious and justly celebrated man was unques-
tionably the most remarkable step ever made for the advance-
ment of the human mind. The element of research he employed
was the descriptive anatomy of the adult or fully-developed indi-
vidual of all, or at least of most, of the species of animals now
occupying the globe. The minute descriptive anatomy of the
species, with a view to the rigorous determination of its true
nature and position in a natural-history arrangement, seemed to
be the ultimatum of all his inquiries ; and if he spoke of genera
or natural families, it was more as a naturalist, or as one by
whom generic distinctions were viewed rather as expressions of
philosophic arrangement than as realities based in Nature. It
was whilst pursuing this inquiry into the existing and living
fauna of the present world, that the thought struck him of
applying the element of research he then wielded with such
dexterity to the fossil remains of a former world : never since
man studied science had a thought so fruitful in great results
entered the human mind. By it he dissected, as it were, the
globe itself, giving to the lovers of truth in science a key where-
with to read those vestiges of successive animal forms which we,
for want of a more correct term, call Vestiges of Creation, and
removed from the mental vision of men that dark veil of igno-
rance which had certainly endured for some thousand years.

"As Cuvier pursued his anatomical investigations, for they
were strictly so, he classified and arranged the individual animals
examined by him into distinct species, according to their anato-
mical differences ; still, adhering to the anatomical method, he
only viewed the distinctions as generic when they were wider,
larger, and quite apparent. Not that he despised external

TRANSCENDENTAL ANATOMY. 397

characters, or neglected them ; but as an anatomist he felt him-
self bound to view them as secondary, and of infinitely less
importance than the anatomical. Moreover, they were wholly
inapplicable, or nearly so, to the fossil world, at least to that
class, the Vertebrata, in which man is most interested.

" If the theory I am about to propose be true, that the young,
namely, of every species, represents a generic animal, embracing
in its structure and natural history characters the possible of all
the species, past, present, and to come, belonging to the natural
family of which it forms a portion, then the natural history of
the fossil world might be guessed at, might be restored, but not
otherwise. The fossil horse was only a horse generically ; but
whether a horse properly so called, an ass, a zebra, a quagga, or
none of these, none can now for certain say : the fossil tiger was
no tiger, in all probability ; nor the bear a bear, appertaining to,
or to be classed with, any species now living. The exterior of
the fossil world is lost for ever ; all that is left of it being merely
the fabulous traditions of rude ages, peopling the world with
monsters,. which the discoveries of Cuvier in some measure corro-
borated.

"When the anatomical method failed in Cuvier' s hands, as it
often did, the illustrious discoverer was thrown upoi^ the field of
hypothesis. The seeming fixity of species was the first stumbling-
block he encountered ; this led to his theory of successive crea-
tions, if that can be called a theory which removes the inquiry
at once from all further investigation. By anatomy it was not
easy, occasionally impossible, to distinguish species from each
other, which, when viewed as clothed with their external attri-
butes, are obviously and notoriously distinct. In this predica-
ment stood the lion and tiger, panther and leopard, horse, zebra,
ass, dog, wolf, fox, jackal, pig, ox, man. The theory of variety,
to a certain extent permanent, was next brought to bear on
these difficult questions ; the influence of domesticity was also
invoked, and even the fruitfulness of hybrid races was asserted ;
so that Natural History fast retrograded towards the silly hypo-
thesis ascribed to Aristotle, who is supposed to have conjectured
that the vast variety of animal forms with which Africa abounds
is due to the arid nature of the country, and its paucity of rivers
and springs, thus bringing together animals of many species and
genera ; hence the varied character of Afric's fauna.

" The inadequacy of anatomy to distinguish species in every
case was fully admitted by Cuvier himself. I also admit this
practically, but with this reservation, that the minute anatomy
of even the osteology of every species differs in a certain degree,
however slight, from every other ; but such minute differences
are not of much importance in the establishment of important
principles, nor can they always be depended on. The nasal

398 ZOOLOGY.

bones of the horse arid ass differ in form from each other, more
perhaps than any part of their respective osteology ; but how
insignificant is this difference, in a natural- history point of view,
when compared with those external characters which mark the
zebra, the horse, the ass, and quagga ! The same remarks apply
to the lion and tiger, in respect of these very bones, the nasal,
and their relations to the superior maxillary bones, to the white
ox of Scotland, and to the common domestic ox. The nasal
bones, the skeleton of the head, the character of the teeth, do
not differ more regularly or constantly, nor to the same extent,
in the horse, zebra, and ass, than they do in the races of man.
The skeleton of the head of the negro and Bosjesman differs
much more widely from the white races of man than those of the
horse and lion differ from the corresponding structures in the
tiger and zebra. I do not, therefore, admit, to the full extent,
that anatomical characters ever fail to discriminate species : but
I freely admit their occasional inadequacy to characterize or to
lead to the determination of species in a practical sense. On the
other hand, the facility with which this may be done, by a con-
sideration of the external characters, is known to all the world.
Science admits of no exaggeration ; Anatomy has done much for
Natural History; much for Philosophy; still more for humanity,
by purging the human rnind of deep-rooted errors, of a gross
and scandalous character, of forty centuries' growth. But Ana-
tomy has its limits, notwithstanding, and these limits were
admitted and defined by the Great Master himself.

" It was not to be expected that a mine of knowledge such as
was discovered and first worked by the great Cuvier, should
continue to be explored by so many vigorous hands, and that all
should go smoothly with the labourers : difficulties soon appeared,
and they increased so rapidly in number and in strength, as to
cloud with anxiety for the fate of his great discovery the mind
of the immortal author of the Ossemens Fossiles. It seemed as if
he were about to survive his own vast reputation. So seem-
ingly unimportant a question as the influence of domestication
over animal life embarrassed the great anatomist. The anato-
mical element of inquiry having failed in establishing specific
distinctions in the various oxen which ornament the cultivated
earth, Cuvier was forced to imagine them fee be like the dog, of
one species ; Goethe, the transceudentalist, starting from a higher
point of view, had arrived at the same conclusion. 'The infinite
varieties of the domestic ox,' observed the sublime author of
Fount) ' are simply the gift to man of domesticity acting through
millions of years/ Sueh also was Cuvier's opinion, omitting the
' millions of years.' What his real opinions were on the influence
of time and circumstances lie never, so far as I know, communi-
cated to any one. The monumental records of Egypt, depicting

TKANSCENDENTAL ANATOMY. 399

man then as he is now, after the lapse of at least four thousand
years, were perfectly well known to him. Still greater difficulties
he prudently passed by, without a passing notice. And yet his
great discovery laid the foundation of Geology, Palaeontology,
and a true history of life on the globe. Before him these sciences
could not be said to exist.

" Prior to this eventful scientific era, the German school of
philosophic anatomists had made an advance towards the same
object, but from a different point of view. Anatomy was still
the element of research which they employed, but it was the
anatomy of the embryo. A.t the head of this school was the
justly-celebrated Goethe, — poet, philosopher, naturalist, mathe-
matician ; his genius seemed universal. He it was who first
distinctly formuled the law of unity of the organization in all
that lives or has lived. The doctrine of 'arrest of development'
came soon after into vogue, chiefly through Meckel and the
German schools of anatomists, — a doctrine based on a superficial
and a somewhat incorrect application of facts, curious and im-
portant in themselves ; to this at last were added tne Teratologie of
Etienne Geoffrey St. Hilaire and the serial unity of De Blainville.

" Believing the transcendental in Anatomy to be the only
instrument of research at present known by which a correct basis
can be laid for the philosophy of Zoology, I have never ceased to
study and teach it since the period (1811) when it first became
known to me. To the writings of Vicq. d'Azyr I am indebted
for the first hints of its existence. Biassed in favour of descrip-
tive anatomy, I have ever objected to the too hasty adoption of
extreme transcendental views, holding it to be a true maxim in
science, as well as in social life, that the change in step or advance,
in order to be certain and trustworthy, must ever be made with
caution, and, if possible, supported by the demonstration of
physical materials ; or, in other words, the thought which genius
submits to the world as an idea must become a physical demon-
stration before the world can fairly be called on to admit its
truth. This is the view I take in the following Memoirs,* in
some of which it is my intention to apply the transcendental to
Natural History, as a preliminary to my inquiry into the natural
history of man. The true relation of species or race to genus or
natural family seemed to me to present a favourable mode of
testing the value of the transcendental, not with any idea of
testing its truth, — that has been settled long ago, — but of ascer-
taining its practical value as an instrument of research. The
true relation of race to natural family being first discovered, it
will then be time enough to apply the transcendental to the rela-
tion presumed to subsist between natural families, and, lastly,

* Published in the Zoologist. Van Voorst. London.

400 ZOOLOGY.

between these and the universal primaeval life of the organic
world of this globe.

" In selecting the natural family of the Salmonidae as a subject
of research, I have been guided by several considerations : I had
already made them the subject of extended research, and their
external characters offered favourable points of view for such an
inquiry. It is chiefly to the exterior that I give my attention in
the present Memoirs ; the interior will follow. I commenced
with the dentition, that natural -history character to which all,
whether naturalists or anatomists, ascribe such importance ; next
followed a brief inquiry into the systems of coloration and propor-
tion. To all these the transcendental applies, or ought to apply,
if true. That it is true as a theory I have not a doubt myself,
however I may fail in proving it to the satisfaction of others.
My immediate object is to prove the existence of a generic animal,
the product, no doubt, of hereditary descent from a species, but
in itself including the characteristics of all the species belonging
to that natural family ; or, in other terms, proving hereditary
descent to have a relation primarily to genus or natural family.
By this term I endeavour to explain family likenesses commingling
with the generic ; the greater or less resemblance, for example,
of an individual with other affiliated races, to none of which it
belongs by strict hereditary descent. My ultimate aim is to offer
a scientific explanation of the appearance, from time to time, of
seemingly new species on the earth, and of the extinction of
others, thus restoring to legitimate science that branch of philo-
sophy which the theory of successive creations, invented by
Cuvier and still maintained by his followers, had clearly removed
from it. To prove the unity of the organization, the unity of
creation, and the serial unity of all that lives or has ever lived,
forms the aim of the first part of this inquiry.

"Probably no class of animals presents so many subjects for
deep contemplation to the philosophic naturalist as the class
fishes. They have furnished the chief materials for the transcen-
dental anatomy of the skeleton ; in the history of the branchial
arches we have the refutation of the * arrest of development'
theory ; in the external characters of the young salmon we have
the proofs that in the young of any of the family of the salmonidae
we may find the types of all the adult speeies of the family, thus
rendering doubtful the theory of the transmutation of species,
and offering the only probable solution of the most difficult of all
questions — the appearance of new species and even genera on
the surface of the globe. Lastly, it is in the same class, fishes,
that we find most distinctly, specialisations recalling the antique
forms of animals which have long ceased to be. In the meta-
morphosis of the young salmon, the fins have at first forms which
belong to extinct species ; next a dentition, so perfect, so com-

THE ANNELIDES OE ENTOMOZOARIA. 401

plete, as to embrace the adult formulas of all existing species of
the family, so that to convert the dentition of one species into
another, nothing is ever added, but merely a something left out.
Contrary, then, to the theories of those who maintain that the
adult alone is perfect, we find that it is the young which, typify-
ing the genus, is entitled to that character. Lastly, it is in them
that a portion of the nervous system acquires a development
equal to the production of electricity ; and in certain of the class
it is that we find the remains of a skeleton, the tegumentary,
which in the extinct world prevailed to an extent of which we
now can scarcely form an idea.

" In the ganoid or mailed extinct fishes, the skeleton which,
from its connexion with the skin, may be called tegumentary or
dermoid (but to which probably the more appropriate name of
neuro-skeleton, as protecting the extremities of the nervous
papillae, might be better applied), reached its highest development
as regards the class fishes ; in the present or living zoology, only
two genera of fishes exhibit a similar arrangement of the tegu-
mentary skeleton, namely, the lepidosteus of the Ohio, and the
polypterus of the Nile. In the sturgeon we find a very complete
tegumentary skeleton, but not arranged in the admirable mecha-
nical manner of the extinct ganoid fishes." — E. K.]

SECOND PRIMARY DIVISION.
THE ANNELIDES OR ENTOMOZOARIA.

§ 507. The animals composing this division are so distinct
from the preceding as to be recognised at a glance. Their
bodies, in fact, are composed of segment-like rings, placed in
a file behind each other. In some, this cumulated appearance
is confined to the existence of a certain number of transverse
folds grooving the skin and engirdling the body, but in most
the animal is enclosed in a sort of solid armour, composed of
a series of rings united to each other, or so articulated as to
admit of motion. This armour serves the purpose in some
measure of a skeleton, for it determines the general form of
the body, protects the soft parts, offers points of attachment
for the muscles, and performs the office of levers ; thus, it is
often called an external skeleton. But it must not be for-
gotten that it is merely the skin hardened and become rigid,
D D

402

ZOOLOGY.

or even encrusted with a calcareous epidermis, and thus is,
at most, a tegumentary skeleton.

§ 508. In certain of the articulata or annelides, as in the
scolopendra (Fig. 164), the rings strictly resemble each other ;
and this tendency to repetition is worthy of observation.
Each ring may carry two pairs of appendages or limbs, one
belonging to its dorsal arch or upper portion (Fig. 413), the
other to the lower or ventral ; and when these appendages
happen to be but little developed, all the rings are, in fact,
provided with limbs. But in general the appendages of cer-
tain rings acquire a large development, as if at the expense
of the others, which in this case remain rudimentary. It
almost always happens that it is the lower appendages which
are thus developed, and which assume varied forms, accord-
ing as the animal is higher or lower in the scale. Differently

Dorsal Arch. Dorsal Oar, or Swimming Paw.

Feet

Ventral Arch. Ventral Oar or Paw.

Fig. 413.— Vertical Section of a Bing or Segment of the Body
of an Ann elide of the genus Amphinome.

modified, they form the antennae, the various organs of mas-
tication, the feet, fins, &c. (Figs. 143, 144). Sometimes the
upper appendages remain and perform, like those of the
inferior arch, the office of feet : various annelides offer
examples of this; but generally they exist merely on the
rings situated towards the middle of the body, and they
constitute the wings, or organs held as analogous to them.
The feet are generally three, four, five, or seven pairs in
number, but occasionally they are in hundreds, and sometimes
altogether absent ; in that case, they seem to be represented
by coarse hair in bundles, as may be seen in earth-worms.

THE ANNELIDES OR ENTOMOZOARIA.

403

§509. The tendency to repetition,
so remarkable in the tegumentary
skeleton of the annelides, extends to
the muscles, nervous system, and
others. In general each segment has
a pair of nervous ganglions ; all these
are united to each other by a double
chain of communicating filaments
occupying the median line of the body
near its ventral aspect (Fig. 162).
In most of the inferior articulated
animals, and in the more elevated,
but whose development is not finished,
these ganglions are almost all equal,
and form, thus connected together,
two chains resembling knotted cords
from one end of the body to the other
(Fig. 414) ; but, as we ascend in the
scale, we find a disposition in these
ganglions to a fusion, in the lateral
and longitudinal sense (Fig. 415), so
as to form a mass. In crabs, this
centralization is carried so far as to
form but two nervous masses for all
the rings or segments of the body, —
one situated in the head, the other
in the thorax ; but even in this case
the nervous collar encircling the
gullet is always found, so that two
such masses seem the maximum of
nervous fusion. In the mollusca we
also find the nervous collar; but
the ventral or post-oasophagal gan-

Fig. 414. — Anatomy of
the Sphinx.*

their course encircling the gullet; c, first pair of post-cesophagal ganglions

mity of the abdomen in the larva.

D D 2

404 ZOOLOGY.

glionary portion is composed in them of only one or two
pairs of ganglions situated on the median line of the body ;
whilst in the annelides we find a long series of ventral gan-
glions ; and when we find in this part of the body merely a
single nervous mass, we know well that it is the result of a
fusion of several ganglions.

Anatomists find in the cephalic ganglions the analogues of
the brain, and in the knotted cord of insects the spinal mar-
row of the vertebrata ; but such views are questionable, and
if any analogy existed, it would rather be found in the gan-
glions situated on the posterior roots of the spinal nerves.

§ 510. In respect of the nervous and locomotive systems,
the annelides stand higher than the mollusca ; but, as regards
the functions of vegetative life, their circulatory system is
less complete, and is occasionally altogether absent. In gene-
ral their blood is white, but not in all, and this difference
seems not much to affect them. Their mode of respiration
varies ; their digestive tube extends from one extremity of the

n I q q p o

Fig. 415.— Anatomy of the Butterfly Sphinx.*

body to the other ; the mouth is placed in the head, and the
anus at the other extremity. Finally, there exist almost
always jaws, or at least particular instruments for the pre-
hension of the food, and these organs are always disposed late-
rally, in pairs, instead of vertically, and before each other, as
in the vertebrata.

This primary division is subdivided into two groups : first,
articulated animals, properly so called; second, verities or
worms. In these there are no limbs, or at least they are
represented merely by tubercles furnished with hairs (seti-
gerous), and the organs of generation are so degraded as to
become at last extremely imperfect.

* The different parts are indicated by the same letters as in the preceding
figure.

CLASS INSECTS.

405

SuB-DlVISION.

ANTHROPODARIA OR ARTICULATED ANIMALS,

PROPERLY SO CALLED.

§ 511. Articulated animals owe their superiority to the
class vermes to the superior development of their nervous and
locomotive systems, and to the more complete localization of
their organs. Some of these characteristic differences have
been already pointed out (§ 380). The following synoptic
table may therefore suffice to recal certain of the characters
peculiar to the various groups.

AETICULATED ANIMALS, properly so called.

Body composed of \
three distinct por-
tions, head, thorax, I
and abdomen ; three { Insecta.
pairs of feet; gene-
rally wings. j

No distinction be-^
tween the thorax and I
abdomen ; twenty- [- Myriapoda.
four pairs of feet or I
Vmore ; no wings. J

Head not distinct from the thorax ; no ") A , . •,
antennae, j Arac Licla'

tio^by^brlnS" } In Seneral five or 8even ?airs of feet' Crustacea.

A head distinct

from the thorax,*

furnished with an-

Aerial respira-
tion by tracheae, or

tennae.

pulmonary sacs.

Head not distinct

CLASS INSECTS.

§ 512. To the definition given of this class of animals in
the annexed synoptic table, we have only to add, that they
have no vascular system properly so called, and that nearly
always they undergo metamorphoses when young. They are
the only invertebrate animals organized for flight.

§ 513. The tegumentary skeleton of insects, that is, the
hardened integuments, preserves sometimes a certain flexi-

406

ZOOLOGY.

bility, but has generally a consistence resembling horn. It
is not horny, however. A substance called chiline forms the
base. It is composed of several pieces, so united as to admit
of motion.

The body, as already described, is composed of rings or
segments placed in a pile; and in this series of segments
three portions are distinguished, — the head, thorax, and
abdomen.

Head.

Tarsus.

Fig. 416. — Anatomy of the Tegumentary Skeleton of a Grasshopper.

The members or appendages connected with these different
rings have a structure analogous to the trunk of the animal ;
they are composed in fact of solid tubes or horny plates, en-
closing in their interior muscles and nerves intended to move
them. -

CLASS INSECTS.

407

The head is formed of a single segment, and carries the
eyes, antennae, and appendages of the mouth. The antennae
constitute the first pair of the members or appendages of
insects, and are composed of a number of joints placed one
before the other. They arise from the anterior or superior

Fig. 417.— Capricorn of the Alps.

Fig. 418.— Horny Paussus.

part of the head, and affect in general the form of flexible
slender horns (# , Fig. 417) ; but their conformation varies,
especially in the males. In some they resemble feathers
(Fig. 419) ; sometimes saws and little clubs (Fig. 418); and
occasionally they are formed of little lamellae, like the leaves

Fig. 419.— Small Bombyx (Paon de Nuit} ; Emperor Moth.

of a book (Fig. 421). Their length is sometimes very con-
siderable. Of their use nothing is known for certain ; but
they may serve for feeling or even hearing.

Three pairs of other appendages arise from the lower part

408

ZOOLOGY.

of the head, constituting organs of mastication or suction.
We shall return to these when speaking of digestion (§ 421
and 522).

§ 514. The thorax of insects occupies the middle portion
of the body, and carries limbs and wings. It is always com-
posed of three circles or rings, named protkorax, meso-
thorax, and metathorax (a I c, Pig. 416) ; and it is to the
ventral arch of each of these rings that one of the pairs of
limbs are fixed. The wings, on the contrary, spring from
the dorsal arch of the thoracic rings ; but the prothorax (a)
never carries any, and there never exists more than a pair of
these appendages on each of the two following rings, so that
there are never more than two pairs.

Fig. 420. — Notonectes.
Boat Fly.

Fig. 421.— Cricket,

§ 515. In the limbs of insects we distinguish a hnunch
composed of two joints, a thigh, and leg, and a sort of foot
called tarsus, divided into several joints, the numher of which
varies from two to five. They terminate in nails. It m<«y
be readily imagined that their forms vary in unison
with the habits of the animals. Thus, insects
which have the hinder limbs long (Fig. 421), leap
rather than walk. In insects which swim, such as
the dystica3, the notonectes^Pig. 420), and the
gyrini, commonly called whirlygigs (Pig. 422), the
tarsi are generally flattened, ciliated, and disposed
like oars ; and in those which can walk on smooth
Gyrinus,or surfaces with the body suspended, we find on the
Whirlygig. terminal joint a sucker, by which they adhere
to the body they touch. Sometimes, also, the
anterior limbs are enlarged, as in moles, to enable them
to dig into the soil. The mole-cricket (Pig. 423), which does

Fig. 422 —

CLASS INSECTS.

409

such mischief by cutting the roots in its course, is an example
of this arrangement.

There are also species in which these same limbs form
organs of prehension, the leg being flexible and disposed like
a claw, the edge being armed with spines. The mantis reli-
giosa (Fig. 424), a large insect of the south of France, is
armed in this way.

Fig. 423.— Mole-cricket.

Finally, there are insects (several diurnal butterflies, Fig.
425) in which the anterior limbs are so small or rudimentary
as to escape notice, as if they had only four pair of limbs.

§ 516. The wings of insects are laminated appendages,
composed of a double membrane, supported internally by
more solid " nervures." When scarcely developed, they are
soft and flexible ; but they soon dry, and become stiff and

Fig. 424. — Mantis Keligiosa ; Keligious or Praying Mantis.

elastic. There are never more than two pairs, sometimes
only one, and they vary in form ; they always spring from
the last two rings of the thorax. When they really serve for
flight they are thin, translucent, and covered with microscopic
scales like dust, as is seen in butterflies ; but the anterior
wings often become hard and opaque, and becoming useless,

410

ZOOLOGT.

as wings form elytra, i. e., protecting sheaths for the others
(a, Fig. 426). At other times these same wings, still mem-
branous towards their extremities, become hard and opaque at
their base, and are then called semi-elytra.

Fig. 425.— Morphe.

Fig. 426. — Capricorne Charpentier.

There are insects in which the wings, instead of being
laminated, are cleft into a number of membranes, barbed on
the edges like feathers, disposed like a fan. This may he
seen in the genus pterophore and orneode (Fig. 427).
Finally, when the posterior wings are wanting, they are

V^ V/^/l

Fig. 427.— Orneode ; Plumed Moth.

usually replaced by two small moveable filaments, terminated
like a club, and named balances (Fig. 428).

§ 517. The abdomen of insects is composed of a consider-
able number of rings, moveable on each other. As many as

CLASS INSECTS,

411

nine may be counted, and when there are fewer it seems as if
some had become fused. In the perfect insect, these rings or
segments have neither wings nor limbs ; but those occupying
the posterior extremity of the body give origin to appendages
varying both in form and size. Sometimes they are simple

Fig. 428.— Conops.

hairs or stylets, whose functions are not well known, as in
the ephemera, for example (Fig. 458). Sometimes these
organs affect the forms of hooks, and constitute more or less
powerful forceps, as in the forficula or earwig (Fig. 429).

Fig. 429.— Forficula ;
Earwig.

Fig. 430.— Podurella ;
Skiptail.

Sometimes they answer the purpose of a spring, to enable the
animal to move forward, as in the podurella (Fig. 430),
small insects, which in our climate conceal themselves under
the stones, or float to the surface of stagnant waters, and
which are sometimes found under the snow in the coldest

412 ZOOLOGY.

regions of the globe. Finally, these abdominal appendages
have at other times a more complex structure, and form an
offensive weapon, as in bees and wasps, or an apparatus
destined to secure a depot for the eggs of the insect in a
place adapted for the development of the young. The sting
of the wasp and bee is formed of two sharp stylets, lodged in
a horny stalk or sheath, having each a furrow, along which
flows the poison secreted in a small gland situated close to it.
In the state of repose, the whole apparatus is drawn within
the body of the animal ; but when the insect wishes to use
it, the sheath is protruded, and along with the sting is driven
into the skin of its enemy. Sometimes it is imposible to
withdraw it, and the whole sting separates then from the
body, remaining implanted in the wound, causing the speedy
death of the insect. The male is always stingless, and thus
can be handled without danger ; but the female and the

Fig. 431.— The Foenus ; Ichneumon or Cuckoo Fly.

working bee are provided with it, and its sting produces a
very painful inflammation. The auger of the fcenus (Fig. 431),
of the ichneumons, and of many other insects, has a somewhat
analogous arrangement ; and we remark also, in general, a
serrated edge, by which the ichneumon divides the entrails,
of the animal or the tissue of the vegetable in which it pur-
poses depositing its eggs. It is by piercing in this manner
an oak of the Levant that a small insect called cynips gives
rise to the formation of the gall-nut, of which so much use

CLASS INSECTS. 413

is made in the fabrication of ink and in the preparation of
dark dyes. The small fissure produced by the auger of the
insect gives rise to an effusion of vegetable juices, and this
produces an excrescence, in the centre of which may be
found the eggs of the cynips.

§ 518. Insects have the organs of sense highly developed ;
they possess sight, smell, as well as tact, taste, and hearing ;
but hitherto the organs of olfaction and audition have not
been discovered : but little is known of the organ of taste.
The structure of the eyes differs very much from that of the
higher order of animals. In general, the organ which at
first sight appears to be a single eye, is in reality formed by
the agglomeration of a number of small eyes, having each a
cornea, vitreous humour of a conical form, -a layer of colour-
ing matter, and a nervous filament. In the may-bug, for
example, we find nine thousand such in a single compound
eye, and there are insects which have more than twenty-five
thousand. All these small cornese are hexagonal, and unite
together so as to form a kind of common cornea, whose sur-
face presents a vast number of facettes. Moreover, each of
these small constituent parts of these multiple or compound
organs is quite distinct from those around it, and forms
with them a bundle of tubes, each terminating in a nervous
filament, proceeding from the terminal enlargement of the
same optic nerve. Almost all insects have a pair of these
compound eyes ; but they are sometimes replaced by simple
eyes, and at other times both sorts are present. The simple
eyes, also called stemmata, have the greatest analogy with
the structure of each of the elements of the compound eyes.
In general, these simple eyes form a group of three on the
summit of the head. Nothing precise is known respecting
the manner in which these eyes act on the light, nor of the
mechanism of vision in insects.

§ 519. Several insects have the power of producing
sounds, which they do by friction of certain parts of their
body on each other, or they may depend on the movements
impressed on the special instruments for the contraction of
the muscles. The monotonous and deafening sounds of the
balm cricket, or chirping grasshopper, result from alternate
tension and relaxation of an elastic membrane, disposed like
the skin -of a drum, over the base of the abdomen ; in crickets,
the sounds are caused by certain parts of the wings, which,
rubbing against each other, vibrate intensely, and the struc-

414

ZOOLOGY.

ture producing this is very singular ; but the buzzing of flies
appears to depend on the rapid escape of the air through the
thoracic stigmata during the violent movements of flight.
Finally, there are other insects which produce sounds by a
mode as yet unknown, such as the nocturnal butterfly or
death's-head sphinx.

§ 520. The nervous system of insects has
been already in a great measure described
(§ 509). It is composed principally of a double
series of ganglions, reunited by longitudinal
cords (Fig. 432) ; the number of the ganglions
corresponds to the number of rings ; sometimes
equidistant and extending from one end of the
body to the other, at other times they approach
each other, and become confused into a nervous
mass. The cephalic ganglions are large, and
give origin to the nerves of the eyes and
antennae, &c. The first pair of ganglions
behind the gullet give off* the nerves of the
mouth, and the longitudinal filaments con-
necting them with the cephalic ganglions
from the nervous collar surrounding the gullet.
Finally, the brain gives off on each side a
nerve, which, ascending on the stomach and
uniting with that of the opposite side, con-
stitutes a median nerve, situated above the
digestive canal, and having in its course two
ganglions. The three pairs of ganglions
following behind the gullet belong to the
three rings of the thorax, and give off the
Fig, 432. nerve of the limbs and wings ; generally
speaking, they are very near each other, and
much larger than the following pairs, which belong to the
abdomen.

§ 521. Insects vary much in their mode of nourishment,
some living on the juice of plants, whilst others feed on solid
aliments, and are either carnivorous or phytophagous; and
these differences correspond to a remarkable modification in
the structure of the mouth. In the grinding insects, such as
the scarabei, the may-bug, the blatta (Fig. 433), the grass-
Jioppers, the opening of the mouth is furnished anteriorly
with a median piece called labium, or upper lip (a, Fig.
434), and presents on each side a kind of large moveable

CLASS INSECTS.

415

tooth, very hard, and called mandible (5, Fig. 434), which
serves to divide the food. Immediately behind these are the

Fig. 433.— Head of the Blatta,
(Cockroach) viewed before.*

Fig. 434. — Buccal Appendages
of the Carabus ; Beetle.

Fig. 435.— Lucanus Metallicus ; Heron Beetle.

* cr, antennae; J, compound eyes; c, single eyes; dt labium; e, man-
dibles ; /, jaws j g, little tongue ; h, labial palpi.

416

ZOOLOGY.

more complex jaws (<?, Fig. 434). Each of these last organs
offers besides a plate or a cylinder, more or less hard, armed
with small teeth or hairs, and carries on its outer side one or
two small stalks composed of several joints, called maxillary
palpi. Finally, behind the jaws is a second pair of appen-
dages, whose base is supported by a median horny piece,
called the chin (d) ; these appendages constitute the languette
or little tongue. They are applied against the jaws as those
are themselves applied against the mandibles ; there exists
besides a pair of articulated and moveable filaments called
labial palpi, because the name of lower lip is usually given to
the chin reunited to the languette. These different parts vary
according to the nature and consistence of the food. The

Labial Feeler. „

Lateral Lobes of the
Little Tongue.

Little Tongue.

Fig. 436.— Head of the Anthophora Eetosa, or Wild Bee.

palpi serve principally to seize the food and to hold it between
the mandibles whilst they divide it. Sometimes the jaws
assume an enormous development, forming a sort of forceps
in front of the head ; this arrangement is very remarkable in
the heron beetle (Fig. 435), and in the other species of the
genus lucanus.

§ 522. For sucking instruments the jaws and the labium
become elongated, so as to form a kind of tubular proboscis,
in the interior of which there are often delicate filaments,

CLASS INSECTS.

417

performing the functions of little lancets, and formed of the
mandible and jaws, extremely modified.

In bees, in the anthophora, wild bee, the bourdon or
solitary bee, and other insects,
called by zoologists hymenoptera,
the buccal apparatus presents a
disposition in some measure in-
termediate between these two ex-
tremes. The upper lip (a, Fig. 437)
and the mandibles (b) greatly
resemble those of the grinding in-
sects ; but the jaws (c) and the
languette (d) are extremely elon-
gated, and the first assume a
tubular form longitudinally, en-
casing the sides of the languette,
so that these organs, reunited
into bundles, form a proboscis,
serving to conduct the food,
always soft and liquid, on which
these insects live. This proboscis
is moveable at its base, and
flexible throughout the rest of its extent, but it is never
rolled up, as we see in the butterfly. With regard to the

Fig. 437.

Fig. 438.— The Wood-Bug.

Fig. 439.— Buccal Apparatus of a
Hemipterous Insect.

ET7I
JS

418

ZOOLOGY.

\

mandibles, they serve chiefly to cut the materials with which
the hymenoptera make their nest, or to seize and put to
death the prey of which these insects suck the juices: It
has been remarked also, that there exist in the interior of

the mouth other solid pieces
which are absent in the
grinding insects, and which
constitute valvules intended
to close the pharynx every
time that deglutition does
not take place.

§ 523. In the wood-
bug, the chirping grass-
hopper, the vine-fretter, and
other hemipterous insects,
the apparatus of suction is
composed of the same ele-
ments, but a little diffe-
rently arranged. The mouth
is armed with a tubular
and cylindrical bill or beak,
directed downwards and
backwards (Fig. 438), and
composed of a sheath en-
closing four stylets ; the
sheath (a, Fig. 439) is in its
turn formed of four joints,
placed end to end, and re-
presents the lower lip;
finally, the stylets (b c),
which have the form of
slender filaments, stiff and
serrated at their summit,
to enable them to pierce the
skin of animals or the tissues
of plants, are the represen-
Fig. 440.-Nemestrina longirostris. tatives of the mandibles and

jaws, extremely elongated.

In the hemiptera, which live at the expense of animals, the bill
is in general very strong, and folded into a semicircle under
the head. In those which are nourished on the juices of
vegetables, it is, on the contrary, almost always slender, and
applied in repose against the inferior surface of the thorax

CLASS INSECTS.

419

between the limbs. Its length is sometimes so considerable
that it passes backwards beyond the posterior extremity of
the abdomen.

In the flies the proboscis, sometimes soft and retractile,
sometimes horny and elongated, represents also the lower lip,
and often carries feelers on its basis ; a longitudinal groove
occupies the superior surface and lodges the stylets, whose
number varies from two to six, and whose analogues in the
bruising or grinding insects are the mandibles, the jaws,
and the languette or little tongue. Sometimes this proboscis
acquires an enormous length (Fig. 440), sometimes, on the
contrary, it is scarcely visible.

Fig. 441 .—Proboscis
of a Butterfly.*

Fig. 442.— Morpha Helenor
( Vampa) .

§ 524. Finally, in the butterflies (Fig. 424), which are
also nourished on liquid substances, but which are found at
the bottom of flowers, and which have no occasion for
cutting or piercing instruments to obtain them, there no
longer exist stylets performing the functions of lancets, as in
the preceding, and the mouth is furnished with a long pro-
boscis (c d, Fig. 441), rolled into a spiral, and composed of
two filaments, hollowed into a groove on their inner surface,
which are nothing but jaws extremely elongated and modi-

* a, head j &, base of the antennae or feelers ; c, the eye ; d, the pro'/oscis j
et palpi.

E E 2

420

ZOOLOGY.

fied in their shape. At the base of this proboscis we distin-
guish anteriorly a small membranous piece, which is the re-
presentative of the labium
or lip, and on each side a
small tubercle, the last
vestige of the mandibles.
We observe also here the
rudiments of the maxillary
palpi, and behind is found
a small triangular lip
carrying two very large
labial palpi, composed of
three joints, and almost
always velvety and covered
with scales (e).

§ 525. The alimentary
canal presents in general a
sufficiently complex struc-
ture ; sometimes it is
straight, and offers pretty
nearly the same diameter
throughout its whole
length; but in general
it is more or less flexuous,
and has several successive
enlargements and contrac-
tions. We distinguish,
then (Fig. 443), a pharynx,
a gullet, a first stomach
or crop, a second stomach
or gizzard, whose walls
are muscular, and often
provided with horny parts
adapted to triturate the
food ; a third stomach,
called the cliylifying
stomach, whose texture is
soft and delicate ; a small
intestine, a ca3cum, and
Fig. 443.— Digestive Apparatus.* a rectum. As ill the

* a, head carrying the antennae, mandibles, &c. ; b, crop and gizzard, fol-
lowed by the chyle-forming stomach; c, biliary vessels; d, intestine; e,
s ecreting organs ; ft anus.

CLASS INSECTS. 421

superior animals, we observe a relation between the nature
of the food and the development the canal requires ; in car-
nivorous insects it is in general very short, whilst in
insects which are nourished on vegetable substances it
is in general very long. The food which reaches it is im-
bibed with saliva ; the apparatus which secretes this liquid
consists in a certain number of floating tubes, terminat-
ing sometimes by kinds of utricles, and communicating with
the pharynx by excretory canals. A multitude of villo-
sities with which the chyle-forming stomach is usually
furnished, seem to serve for the secretion of a gastric juice,
and it is also in this cavity that the bile is poured. There
exists no liver, properly speaking, in insects ; but this organ
is replaced by long and delicate tubes, which float in the
interior of the abdomen, and open superiorly into the chyle-
forming stomach (c, Fig. 443). These biliary vessels also
take the place of urinary glands, for it is here that the uric
acid is formed. By one of their extremities they always
open into the chyle-forming stomach, and the other extremity
is sometimes free, sometimes fixed to the intestine, whether
near the first opening or in the neighbourhood of the rectum.
Finally, we still find, towards the posterior extremity of the
intestinal canal, other secreting organs (e) serving to elabo-
rate particular fluids (such as the venom of the bee) which
several insects eject from the extremity of the abdomen when
they are disturbed.

§ 526. It would appear that it is by simple imbibition
that the chyle traverses the walls of the digestive tube, and
mingles with the blood. This last liquid is watery and
colourless ; it is not enclosed in vessels, arid is found spread
about in the interstices which the organs have between them,
or present in the substance of their tissue. Insects also have
no regular circulation. We perceive, indeed, in certain parts
of their bodies, currents even sufficiently rapid, but the
nourishing liquid does not describe a circle so as to return
constantly to its point of departure. There exists, in fact, in
these animals only the vestiges of the circulating apparatus
(§ 112). We observe near the dorsal surface of the body a
longitudinal tube (Figs. 414 and 415), which performs alter-
nate movements of contraction and of dilatation, analogous to
those of the heart in the superior animals. But this dorsal
vessel seems to give off no branch. The nourishing liquid
penetrates into it by lateral openings, furnished with valvules

422 ZOOLOGY.

to prevent its repulse, and escapes from it by its cephalic
extremity. Moreover, the motion of the blood does not
depend altogether on this organ, for there have been dis-
covered in several insects moveable valvules, whose pulsations
determine in this liquid rapid currents, and strange to say, it
is in the limbs that this apparatus is lodged.

§ 527. The blood become venous by its action on the
different tissues of the economy, is thus unable to reach, a
determinate part of the body, to place itself in contact with
the oxygen, and thus to recover its vivifying qualities. If
the respiration were accomplished in the ordinary way, by
the aid of lungs or by the external surface of the body, it
would have been consequently extremely incomplete ; but the
disadvantage which would seem necessarily to have resulted
from this great imperfection in the so important function of
the circulation does not in reality exist. Nature has made
amends for the rapid and regular transport of the blood by
conducting the air itself into all parts of the body by means
of a multitude of canals which communicate with the exterior,
and are infinitely ramified in the substance of these organs
(Fig. 57).

Fig. 444. — Male Lampyris Fig. 445. — Female Lampyris.
(Glow-worm)

These air-bearing tubes, designated, ^s we have already
said (§ 133), under the name of trachea, present a complex
structure ; they are composed generally of three tunics, of
which the middle one is formed of a cartilaginous filament
rolled into a spiral, like the elastic of a strap (bretelle].
Sometimes they are simple, but at other times they present a
certain number of large swellings, in the form of soft vesicles,
which perform the functions of a reservoir of air (Fig. 57).
The apertures by which the air penetrates into the trachea are
called stigmata; they resemble in general a small button-
hole, but these often have valves which open and shut like

CLASS INSECTS. 423

the folding or clapper of a door. A pair may generally be
seen on the lateral and upper parts of each ring ; but they
are often absent in the last two segments of the thorax.

With regard to the mechanism by which the air is renewed
in the interior of this respiratory apparatus, it would seem
to consist generally in the movements of contraction and
dilatation of the abdomen. Thus, as we have already said
elsewhere, the respiration is very active in these animals.
They consume a considerable quantity of air, compared with
their bulk, and speedily asphyxiate when deprived of oxygen ;
but when they are in this condition of apparent death, they
can continue so for a great length of time without losing the
faculty of returning to life.

§ 528. Most insects produce but very little heat ; but
some of these animals disengage, under certain circumstances,
a sufficiency notably to raise their temperature. Bees offer
an example of this, especially when they are much agitated
in their hive ; and it is to be observed that the respiration
becomes then very active.

§ 529. Another and a more remarkable phenomenon, and
of which the cause is still unknown, is the production of
light observed in some insects. The lampyris or glow-ivorm
is an example of this, well known to all who frequent the
fields : the male (Fig. 444), which has wings, is but little
luminous ; the female (Fig. 445), which has no wings, and
which is often found during the warm nights of summer on
the thickets, spreads around a very lively phosphorescent
light. In another species of lampyris inhabiting Italy, the
individuals of both sexes are at the same time winged and
luminous ; but this singular property is especially remarkable
in certain taupins inhabiting the hot regions of America, and
which produce, whilst they vault in the obscurity, a natural
illumination of the happiest effect; the women frequently
place them in their hair as ornaments, and it is asserted that
the Indians make use of them to point out the way during
the night. In one lampyris, the light comes from certain
spots situated over the two or three last rings of the abdo-
men ; whilst in the taupins it comes from analogous spots
over the prothorax or corslet. It appears that the insect can
vary at will the intensity of the phosphoric light, and that it
is connected with the action of the oxygen upon a fatty
matter secreted by the phosphorescent organs.

§ 530. The sexes are distinct in these animals, and there

424 ZOOLOGY.

exist often great differences between the male and the female :
the common lampyris has already offered us an example
(Figs. 444, 445). Almost all insects lay eggs : nevertheless,
some are viviparous. There often exists at the extremity
of the abdomen of the female a dart, a wimble, or some other
organ, destined to form holes adapted to receive the eggs ; and
by an admirable instinct the mother uniformly deposits these
in a place where the young will find themselves in proximity
with the food they require, even although it be in most cases
not the kind which the parent lives on.

In youth, insects change their skin several times, and pre-
sent almost always a phenomenon of the most remarkable
kind, of which, however, we have already seen an example in
the batrachia. Most of them, on quitting the egg, neither
resemble their parents nor what they will themselves after-
wards become, and undergo, before arriving at the perfect
state, changes so considerable as to constitute a true meta~
morpkosis.

Fig. 446.— Swallow-tailed Butterfly (Larva of the Butterfly Machaon).

In general, insects pass through three conditions, quite
distinct, which have been named the larva state or condition
(Fig. 446), the nymph state (Fig. 447), and the perfect state
(Fig. 448); but the changes they undergo are not always
equally great. Sometimes these changes render the animal
altogether unrecognisable, at other times they consist only
in the development of wings ; and these various degrees of
transformation are known by the names of complete meta*
morphoses or of semi-metamorphoses.

§ 531. Insects which undergo a complete metamorphosis
are always more or less vermiform when they leave the egg
and when they are in a state of larva (Fig. 446). Their body
is elongated, almost entirely soft, and divided into moveable
rings, of which the regular number is thirteen. Sometimes
they are altogether without limbs : at other times they have

CLASS INSECTS. 425

a variable number of these organs, but whose conformation
in no shape resembles that of the same parts in the adult
animal. Almost always they" have merely simple eyes, and
they are sometimes completely without any. Finally, their
mouth is almost always armed with mandibles and jaws,
whatever be the conformation which they assume in the end ;
and we often see the first of these organs serve for locomotion
as well as for the prehension of the food. These larvse vary,
moreover, in their form, and are known sometimes under the
name of cheville (caterpillars) ; sometimes, but erroneously,
under the name of worms.

Fig. 447.— Chrysalis of the Machaon ; Swallow-tailed Butterfly.

After having remained in this condition during a longer or
shorter period, and after having experienced several moultinqt,
their wings form under the skin, and they change into nymphs
(cliry solids]. During the whole duration of this second
period of their existence, these singular animals cease to take
food, and remain immovable. Sometimes the skin which
they have just shed dries up, and forms a sort of oviform case,
in the interior of which they remain enclosed ; sometimes they
are only covered with a thin pellicle, which, applied closely
over their external organs, follows all their contours, and
resembles linen, in which the insect is encased or bandaged.
This last arrangement, which is seen in the nymphs of butter-
flies or chry solids (Fig. 447), has obtained for them the
name of pupa or of maillot*

Before undergoing this metamorphosis, the larva often pre-
pares a refuge, and shuts itself up in a case, which it makes
with silk, secreted by glands analogous to the salivary glands,
and prepared by means of winders -hollowed out in its lips.
At other times it suspends itself by means of filaments (Fig.
447), or conceals itself in some hole. It is while the insect
is in this state of apparent repose that there takes place in

* Literally, swaddling-clothes.

426 ZOOLOGY.

the interior of its body an active labour, the result of which
is the complete development of all its organization. Its in-
ternal parts soften, and by little and little assume the form
which they are afterwards to maintain. The various organs
with which the adult animal is to be provided become developed
under the envelope concealing them, and when this evolution
is finished, it frees itself of this kind of mask, unfolds its
wings, which soon acquire consistence, and becomes a perfect
insect.

Fig. 448.— Papillon Machaon ; Swallow-tailed Butterfly.

§ 532. As an example of these metamorphoses, we could
not choose a better than that of the bombyx of the mulberry ;
for this insect, in the state of a larva, is for us of immense
interest. It is the silkworm, the rearing of which contributes?
so powerfully to the agricultural prosperity of our southern
provinces, and whose products support so many wealth-pro-
ducing employments. This insect, originally from the northern
provinces of China, was introduced into* Europe only in the
sixth era. Some Greek missionaries brought the eggs to
Constantinople during the reign of Justinian, and at the
epoch of the first Crusades its culture spread into Sicily and
Italy ; but it was only in the time of Henry the Fourth that
this branch of agricultural industry acquired some importance
in our southern provinces, of which it forms, at the present
day, one of the principal sources of wealth.

The eggs of the mulberry bombyx are known to agricul-
turists by the name of seed of the silkworm. When they
have been exposed to the air they have an ashy-grey tint,

CLASS INSECTS. 427

and with some care they may be thus preserved for a suffi-
ciently long time without becoming deteriorated. In order
that incubation commence, and that the larvae appear or un-
fold themselves, it is necessary that the eggs be placed for
some time under the influence of a temperature of at least
15° or 16° Cent. (59° Fahr.). After having experienced eight
or ten days of increasing heat they become whitish, and soon
after the larvae begin to come forth. These small animals
at the moment of their birth are only about a line and a
quarter in length. Their body (Fig. 449) is elongated, cylin-
drical, annulated, smooth, and generally of a greyish colour.
At its anterior extremity may be distinguished a head, formed
by two kinds of hard scaly caps, on which may be remarked

Fig. 449.— Silkworm.

black points, which are the eyes. The mouth occupies the
anterior part of this head, and is armed with strong jaws.
The three following rings have each a pair of small scaly
limbs, and represent the thorax. Finally, the abdomen is
very large, and has no limbs on the first two segments, but
is furnished posteriorly with five pairs of fleshy tubercles,
which resemble stumps, and which constitute so many limbs.
In the south of France silkworms are called magnans, and
hence the name of magnanerie given to the establishments
in which they are reared. The first care they require after
their birth is to separate them from their cocoons, and to

428 ZOOLOGY.

place them on hurdles, where they find nourishment appro-
priate to their wants. For this purpose it is usual to
cover the eggs with a sheet of perforated paper, through
the holes made in which the worms ascend to reach the leaves
of the mulberry placed above ; and it is when they are on the
branches furnished with these leaves that they are trans-
ported on the hurdles prepared to serve as their dwellings.
The nourishment of the silkworm consists in the leaves of
the mulberry (Fig. 449), and it is consequently on the cul-
ture of this plant that the possibility of rearing these insects
depends. The white mulberry is the species most generally
employed for this purpose ; it is a tree which grows to the
height of forty or fifty feet, and which gives four or five
quintals'* of leaves, sometimes even ten or twelve. It accom-
modates itself sufficiently well in most localities, and it has
been cultivated with success even in the north of Europe, but
it grows nowhere wild. In fact, this mulberry-tree is origi-
nally from China. Two Greek monks introduced it into
Europe towards the middle of the sixth era, and the silk-
worm with it.f Its culture soon spread throughout the

* Quintal, — one hundred pounds weight.

t " I need not explain that silk is originally spun from the bowels of a
caterpillar, and that it composes the golden tomb from whence a worm
emerges in the form of a butterfly. Till the reign of Justinian, the silk-
worms, who feed on the leaves of the white mulberry tree, were confined to
China ; those of the pine, the oak, and the ash were common in the forests
both of Asia and Europe, but as their education is more difficult, and their
produce more uncertain, they were generally neglected, except in the little
island of Leos, near the coast of Africa. A thin gauze was procured from
their webs ; and this Leon manufacture, the invention of a woman, for female
use, was long admired both in the East and at Rome. Whatever suspicions
may be raised by the garments of the Medes and Assyrians, Virgil is the
most ancient writer who expressly mentions the soft wool which was combed
from the trees of the Seres or Chinese ; and this natural error, less mar-
vellous than the truth, was slowly corrected by the knowledge of a valuable
insect, the first artificer of the luxury of nations. That rare and elegant
luxury was censured in the age of Tiberius by this gravest of the Komans.
Two hundred years after the age of Pliny, the use of pure, or even of
mixed silks was confined to the female sex, and all the opulent citizens of
Rome and the provinces were insensibly familiarized with the example of
Heliogabalus, the first who, by this effeminate habit, had sullied the dignity
of an emperor and a man. Aurelian complained that a pound of silk was
sold at Rome for twelve ounces of gold ; but the supply increased with the
demand, and the price diminished with the supply.

" As silk became of indispensable use, the Emperor Justinian saw with
concern that the Persians had occupied by land and sea the monopoly of this
important supply, and that the wealth of his subjects was continually drained
by a nation of enemies and idolaters. An active government would have
restored the trade of Egypt and the navigation of the Red Sea, which had
decayed with the prosperity of the Empire ; and the Roman vessels might
have sailed, for the purchase of silk, to the ports of Ceylon, of Malacca, or

CLASS INSECTS. 429

Peloponnesus, and it gave to this part of Greece the modern
name of Morea. From thence the mulberry and the silk-
worm passed into Sicily, by the care of King Eoger, and
acquired in Calabria a rapid extension. Some gentlemen who
had accompanied Charles the Eighth into Italy during the
war of 1494, having discovered all the advantages which
that country drew from this branch of agriculture, were

even of China. Justinian embraced a more humble expedient, and solicited
the aid of his Christian allies, Ethiopians of Abyssinia, who had recently
acquired the arts of navigation, the spirit of trade, and the seaport of
Adulis, still decorated with the trophies of a Grecian conqueror. Along the
African coast, they penetrated to the Equator in search of gold, emeralds,
and aromatics ; but they wisely declined an unequal competition, in which
they must be always prevented by the vicinity of the Persians to the markets
of India ; and the Emperor submitted to the disappointment, till his wishes
were gratified by an unexpected event. The gospel had been preached to the
Indians ; a bishop already governed the Christians of St. Thomas, on the
pepper coast of Malabar ; a church was planted in Ceylon, and the mission-
aries pursued the footsteps of commerce to the extremities of Asia. Two
Persian monks had long resided in China, perhaps in the royal city of
Nankin, the seat of a monarch addicted to foreign superstitions, and who
actually received an embassy from the isle of Ceylon. Amidst their pious
occupations, they viewed with a curious eye the common dress of the Chinese,
the manufactures of silk, and the myriads of silkworms, whose education,
either on trees or in houses, had ouce been considered as the labour of
queens. They soon discovered that it was impracticable to transport the
short-lived insect, but that in the eggs a numerous progeny might be pre-
served and multiplied in a distant climate. Eeligipn or interest had more
power over the Persian monks than the love of their country. After a long
journey they arrived at Constantinople, imparted their project to the Em-
peror, and were liberally encouraged by the gifts and promises of Justinian.
To the historians of that prince, a campaign at the foot of Mount Caucasus
has seemed more deserving of a minute relation than the labours of these
missionaries of commerce, who again entered China, deceived a jealous
people by concealing the eggs of the silkworm in a hollow cane, and returned
in triumph with the spoils of the East. Under their direction, the eggs were
hatched at the proper season by the artificial heat of dung ; the worms were
fed with mulberry leaves ; they lived and laboured in a foreign climate j a
sufficient number of butterflies was saved to propagate the race, and trees
were planted to supply the nourishment of the rising generations. Expe-
rience and reflection corrected the errors of a new attempt, and the Sogdoite
ambassadors acknowledged, in the succeeding reign, that the Romans were
not inferior to the natives of China in the education of these insects and the
manufactures of silk, in which both China and Constantinople have been
surpassed by the industry of modern Europe. I am not insensible of the
benefits of elegant luxury ; yet I reflect with some pain, that if the importers
of silk had introduced the art of printing, already practised by the Chinese,
the comedies of Menander and the entire decades of Livy would have been
perpetuated in the editions of the sixth century. A larger view of the globe
might at least have promoted the improvement of speculative science, but
the Christian geography was forcibly extracted from texts of Scripture, and
the study of nature was the surest symptom of an unbelieving mind. The
orthodox faith confined the habitable world to one temperate zone, and
represented the earth as an oblong surface, four hundred days' journey in
length, two hundred in breadth, encompassed by the ocean, and covered by
the solid crystal of the firmament." — Decline and Fall, vol. vi.

430 ZOOLOGY.

desirous of conferring the gift on their native country, and
so caused the mulberry to be transplanted from Naples inta
Provence and Dauphine. It is but thirty years ago when
might be seen still at Allan, near Montelimart, the first of
these trees which was planted in France. It was brought
there by Guy Pope of St. Auban, lord of Auban. At present,
the mulberry covers a great part of the south of France, and
is cultivated even in the north.

Fig. 450.— China Silkworm.

[The caterpillar of this silk moth or butterfly lives on the
leaves of the oak, and on this account attempts are now being
made to introduce the species into France and Europe generally.
— R. K.]

Silkworms live in the state of a larva about thirty-four
days, and during this time change their skin four times ;

CLASS INSECTS. 431

the time comprised between these successive moultings con-
stitutes what the agriculturalists call the various ages of
these little animals. At the approach of each moulting they
become as if dormant, and cease to eat; but after having
changed their skins their hunger redoubles. They call petite
freze the moment of the great appetite which precedes each
of the first four moultings, and grande freze that which is
observed during the fifth age of the worm. The quantity of
nourishment which they consume increases rapidly. It is
reckoned that for the larvae springing from an ounce of seed,
seven pounds of leaves are required during the first age, the
duration of which is five days ; twenty-one pounds during
the second age, which continues only four days; seventy
pounds for the third age, which lasts seven days; two hundred
and ten pounds during the fourth age, which continues seven
days ; and from twelve to thirteen hundred pounds during
the fifth age. It is on the sixth day of the last age that the
grande freze takes place. The worms devour then from two
to three hundred pounds of leaves, and cause, whilst eating, a
noise like a heavy shower of rain. The second day they
cease to eat, and prepare themselves to undergo the first
metamorphosis. They may be seen then to climb the branches
of small faggots placed intentionally and carefully above the
hurdles in which they had hitherto remained. Their bodies
become soft, and there springs from their mouth a thread of
silk which they draw after them. Soon they fix themselves,
throwing around them a multitude of threads of extreme
fineness, called bane or banne, and, suspended in the middle
of this network, spin their cocoon, which they construct by
continually turning on themselves in different ways, and thus
rolling around their body the thread which leaves the winder
with which their lip is pierced. The thread thus formed is
produced by glands which have much analogy with the
salivary glands of other animals, and the matter of which
it is composed is soft and viscous at the moment of its leaving
the mouth, but soon hardens in the air. From this it results
that the different turns of this single thread become agglu-
tinated together, and form an envelope whose tissue is firm,
and whose shape is ovoid. The colour of this silk varies ;
sometimes it is yellow, sometimes pure white, according to
the variety of the worm which has produced it, and the
length of each thread often exceeds six hundred metres,
(somewhat more than six hundred yards), but it varies much,

432 ZOOLOGY.

as well as the weight of the cocoons. The worms produced
from a single ounce of seed may produce as much as one

Fig. 451.— Abraxas gross ulanata.

Fig. 452.*

* Silkworm of the Castor-oil plant, represents the butterfly, the cater-
pillar, and the cocoon or pod; also the leaves of the plant. Quoted from
the work on aeclimatation. by the late Isidore Geoffrey St. Hilaire. —
E.K.

CLASS INSECTS.

433

hundred and thirty pounds, hut such a harvest is rare, and
often they obtain only from seventy to eighty pounds from the
cocoons.

In general, from three days and a half to four days suffice
for the larvae to finish their cocoon, and if we afterwards open
this kind of cellule we may see that the animal (Fig. 455)
no longer offers the same appearance as before its seclusion ;
it has acquired a brown colour, its skin resembles old leather,
and its form is ovoid, a little pointed at its posterior extre-

Fig. 453.— Silkworm of the Ailantus.*

mity. Neither head nor jaws are to be any longer distin-
guished, but its posterior portion is occupied by moveable
rings, whilst anteriorly an oblique band may be observed,
disposed like a scarf, and representing the future rings of the

* Silkworm of the Ailantus from India and the extreme East. All these
various kinds of silks have their peculiar qualities or properties.— R< K.
F F

434

ZOOLOGY.

perfect animal. The time during which the bombyces re-
main thus shut up in a state of chrysalis, varies according to
the temperature. If the heat be from 15° to 18° (from 59°
to 65° Fahrenheit), they come out in the perfect state from
the eighteenth to the twentieth day. To pierce their cocoon,
they moisten one extremity with a particular liquid which
they disgorge, and afterwards they strike their heads violently
against the point thus softened. When the bombyx has in
this manner finished its metamorphoses, it appears under the
form of a butterfly with whitish wings (Fig. 454) ; its mouth
is no longer armed with jaws as when young, but is pro-
longed into a proboscis rolled into a spiral; its limbs are
slender and elongated, and its internal conformation differs
as much from that of the larva as its external form. Soon
after their birth the papillons seek each other ; afterwards
the females lay their eggs, the number of which amounts to
more than five hundred for each of these insects; finally,
after having lived in the perfect state from ten to twenty
days, they die.

Fig. 454— Bombyx, or Moth of the Mulberry. Fig. 455.— Chrysalis

of this moth.

§ 533. The bees, of which we have already had occasion
to speak (§ 332), experience changes still greater, since in
the larva state they have no limbs, and resemble little
worms. It is the same with flies, gnats, and a great number
of other insects ; thus the vermiform animals which swarm
in putrid flesh, and which are known by the common name
of maggots, are nothing else but the larvaB of the golden fly.
Gnats, which at night vault in the air in numerous groups,

CLASS INSECTS.

435

and which are so harassing to man by their envenomed
sting, live in water whilst in.x their larva state. They are
then vermiform, without limbs, and have the abdomen ter-
minated by bristles and appendages disposed in rays (Fig.
456) ; finally, the last ring but one gives origin to a tube
sufficiently long (t), by means of which the animal draws
from the atmosphere the air it requires. To breathe in this
way, it suspends itself as it were to the surface of the water,
with the head downwards, and we see it at short intervals
renew its arrangement. The nymph continues to live in
water and to move in it, but instead of breathing like the
larva, it obtains the air which it requires through the medium
of two tubes placed under the thorax. It floats on the surface

Fig. 456.— Larva of the
Gnat.

Fig. 457.— Gnat, magnified.

of the liquid, and after having accomplished its metamor-
phoses, the perfect insect (Fig. 457) employs its cast-off
covering whilst a nymph as a barge or boat, until its long
limbs and wings have acquired sufficient solidity to permit it
to walk on the surface of the water or to fly away ; for if its
body happened to be submerged, as occurs often when the
wind upsets its frail embarkation, it would infallibly be
drowned.

§ 534. The insects which undergo a semi-metamorphosis,
also pass through the state of larva and nymph before arriving
IFF 2

436

ZOOLOGY.

at their perfect state ; but here the larva differs only from the
perfect insect by the absence of wings, and the state of nymph
is only characterized by the growth of these organs, which, at
first folded and concealed under the skin, become then free,
but acquire all their development only at the epoch of their
last moulting.

Fig. 458.— Ephemera; Day-fly.

We may cite as examples of insects presenting this kind of
metamorphoses the grasshopper and the ephemera (Fig. 458).
These last present even a remarkable peculiarity ; for in
general insects change their skin for the last time when they
pass from the stage of nymph to their perfect state, whilst
the ephemera experiences another moulting before
becoming completely adult, although in this state
it lives but a few hours. The larva of this
ephemera lives in water, and differs but little from
the adult, excepting in the shortness of its limbs,
the absence of wings, and by the row of Iamina3
or plates which it has on each side of the abdomen,
and which it employs as organs of respiration and
of swimming. The nymph (Pig. 459) only
differs from the larva by the presence of sheaths
enclosing the wings. At the moment when these
organs are to be developed,~lthe insect quits the
water, and after having vaulted in the air for some
minutes, proceeds to rest upon an elevated object,
when it abandons itself to violent movements, by
Fig. 459. means of which it throws off its tegumentary
membrane ; it is then only that its limbs ac-
quire all their length, and its body the colours it is after-
wards to preserve.

§ 535. Some insects, although they undergo considerable
changes when young, do not pass through the complete series
of transformations of which we have just spoken; they seem,

CLASS INSECTS. 437

as it were, to stop en route, and never come to possess wings.
Fleas are in this case, and, leaving the egg, they have no
feet, and have the form of small worms, of a whitish colour.
These larvae are very lively, and roll themselves into a circle
or spiral. Soon they become reddish, and after having lived
in this state a dozen days, they shut themselves up in a small
silky cocoon of extreme fineness, to be transformed into a
nymph; then, at the end of about twelve days of seclusion,
if the time be warm, they leave the envelope in the perfect
state.

§ 536. Finally, there are also insects which do not undergo
a metamorphosis, and which are born with all the organs
they are ultimately to possess ; but it is always the apterous
insects which offer us this mode of development. The podu-
rella (Fig. 430), already spoken of, and the louse (Fig. 491)
offer examples of this.

§ 537. Insects, so remarkable by their organization, are
still more so by their habits, and by the admirable instinct
which nature has bestowed on so many of them. The arti-
fices they employ to procure their food, or to withdraw them-
selves from their enemies, and the industry they display in
their labours, astonish all who have witnessed them ; and'
when we see them unite into numerous societies, to make up
for their individual feebleness, assist each other, divide
amongst them the works necessary to the prosperity of their
community, provide for their future wants, and frequently
even regulate their actions according to the accidental circum-
stances in which they may be placed, one remains confounded
to find, in these beings, so small and apparently so imper-
fect, instinct so varied and so powerful, and intellectual com-
binations which so strongly resemble reasoning or judgment.
The subject would not become exhausted if we felt inclined
to relate here examples of these curious phenomena, but the
narrow limits of these lectures do not permit us to consecrate
at this moment more time to this subject ; and we can only
refer our readers to what we have already said whilst
treating in a general way of the actions of animals (§ 317
to 339).

§ 538. Classification of In sects. — If we now endeavour
in a few words to sum up the more important differences
which insects present, we shall find that these differences
depend especially on the structure of the mouth, which regu-
lates the regime of these animals ; in the disposition of the

438

ZOOLOGY.

organs serving for aerial locomotion, a function which gives
to the entire class one of its most prominent characters ;
finally, on the kind of metamorphoses which these beings
undergo when young. Now, after what we have said else-
where respecting the essence of natural classification, it is
evident that it ought in consequence to be
in the modifications of the buccal apparatus,
of the wings, and of their mode of develop-
ment, that the zoologist should look for the
basis of a methodical distribution of these
animals. In fact, it is in this way that they
have come to divide them into a certain
number of orders, to which have been given
the names of coleoptera, ortkoptera, neu-
roptera, hymenoptera, lepidoptera, hemip-
tera, diptera, rhipiptera, anoptura, and thysanura.

§ 539. The coleoptera as well as the orthoptera and the
neuroptera, are formed to be. nourished on solid substances,
whether animal or vegetable, and are furnished for this pur-
pose with mandibles and jaws adapted for the division of this
kind of food (Fig. 434). They have two pairs of wings, but
those of the first pair are not adapted for flight, and consti-
tute a sort tf hard and horny bucklers called elytra (a, Fig.
426).

Fig. 460.- Wimble
(Ptinus).

Fig. 461. — Scarabasns (or Alescus),
Sacred Beetle of the Egyptians.

Fig. 462.— Dermeste
du Lard ; Lard Insect.

The wings of the second pair are, on the contrary, mem-
branous, transparent, and too long to be concealed under the
elytra without being folded across j sometimes they are alto-

CLASS INSECTS.

439

ig;, 463.— Larva of the
May-bug, or Cockchafer.

gether wanting, and then the insect cannot fly ; this is the
case with the charancon (the weevil) which destroys our
granaries, and is remarkable for its head, prolonged into the
form of a beak.

The coleoptera undergo complete
metamorphoses. The larva resembles
a worm with a horny head, whilst the
rest of the body is almost always soft
(Fig. 463); its mouth is formed in
the same way as that of the perfect
insect ; the three rings which follow
the head have each of them almost
always a pair of limbs, generally very
short ; finally, there exists in a great
number of these animals a pair of

false limbs attached to the last segment of the abdomen. The
nymph is inactive, and takes no nourishment; it is covered
with a membranous skin, applied exactly over the subjacent
parts, and permits their being seen.

Most of these insects are remarkable for the hardness of
their integuments and the brilliancy of their colours. Some
are carnivorous, — the gilded carabus (beetle) or gardener
(Fig. 9), so common in the sandy walks, for example; others,
as the may-bug, live on vegetables.
Their number is immense, and already
thirty thousand species are known;
but we shall limit ourselves here to
mentioning only the scarabsei, of which
one species (Fig. 461) is celebrated,
by reason of the respect with which it
was viewed by the ancient Egyptians ;
the cantharides, or Spanish flies (Fig.
464), which, in the south of France
and of Spain, live on the ash-tree and
the lilac, and furnish to medicine a
very energetic blistering substance ;
the weevils, which live on grain ; the
wimble (Fig. 460) (Ptinus), and the
wood piercers, which in the state of
larva perforate the wood of old fur-
niture and timber- work ; the dermestes (Fig. 462), whose
larvae live on the cast-off skins of other animals ; and
often in this way destroy furriery and zoological collections ;

Fig. 464.— Cantharis,
or Spanish Fly.

440 ZOOLOGY.

finally, the coccinella or ladybird, the cicindela, the carabus,
(Fig. 9), &c.

§ 540. The orthoptera resemble the preceding by the
general disposition of the organs of mastication, as well as by
the number and consistence of their wings, but are distin-
guished by the manner in which their posterior wings are
folded, and by the nature of their metamorphoses. The elytra
are less hard than in the coleoptera, and the membranous
wings (Fig. 465) when they are at rest are not folded trans-
versely, but merely longitudinally, in the manner of a fan.
They undergo only a semi-metamorphosis, and the larva as
well as the nymph resembles a perfect insect, excepting as
regards the wings. Finally, all are terrestrial, and most of
them are remarkable for the elongation of their body and for
the extreme development of their posterior limbs, which
makes them leaping animals.

Fig. 465.— Locust.

The locusts and crickets (Fig. 421) are the principal repre-
sentatives of this group ; but in it are also arranged the
mantis (Fig. ;424), the leaf-insect (Fig. 468), the cricket
(Fig. 467), the mole cricket (Fig. 423), the cockroach (Fig.
466), and the forficula (Fig. 429),

CLASS INSECTS.

441

§ 541. The neuroptera are distinguished from other mas-
ticating insects by the structure of their wings, four in
number ; these are all membranous, transparent, of extreme
delicacy, and of equal utility for flight. The body of such

Fig. 466.— Cockroach.

insects is generally soft, and very elongated. Finally, some
undergo a complete metamorphosis, others only a semi-meta-
morphosis. This order comprises the libellube (Fig. 469),

Fig. 467.— House Cricket.

the agrions (Fig. 171), the ephemera (Fig. 458), the ant-
lion (Fig. 115), the phryganidse, the termites, &c.

These last insects, known also by the name of white ants,

442

ZOOLOGY.

are very destructive ; they are met with chiefly in warm
countries, but they cause considerable destruction in some
parts of France, as at Roehelleand at Kochefort, for example :
they destroy the timber of carpenters* work, and live in
numerous societies, composed of winged males and females,
of wingless neutral individuals, and of the young.

Fig. 468.— Leaf Insect (Phyllium Succifolium) .

§ 542. The h}7menoptera establish in some measure the
passage between masticating and sucking insects : they have
in front mandibles very like the first, but which do not serve
for mastication, and they are nourished with soft or liquid
matters, which they suck up by means of a moveable and
flexible proboscis, composed of gums and of the languette
extremely elongated (Fig. 436). They have, like the neu-
roptera, four membranous and transparent wings; but these

CLASS' INSECTS.

443

wings, instead of being reticulated like lace, are divided into
a certain number of tolerably large cellules by horny nervures,
and they cross each other horizontally on the body during
repose. These integuments are not very hard, and the
abdomen of the female is terminated by a wimble or dart.

These insects undergo a complete metamorphosis. The
larva, sometimes deprived of wings, resembles a worm ; at
other times, having six feet, with hooks, and often also from
twelve to sixteen membranous feet, it more resembles a cater-
pillar. In both cases it has a scaly head, with mandibles,
jaws, and a lip, at the extremity of which is a winder for the
passage of the silky matter of which the cocoon is to be con-
structed. The regime of these larvae varies much. Several

Fig. 469.— Dragon Fly (Libellula depressa).

require foreign aid, and are brought up in common by sterile
individuals, reunited into a society, as we have seen in speak-
ing of bees (§ 332). The nymph remains without nourish-
ment, and in complete repose. Finally, in their perfect state,
the hymenoptera live almost all on flowers, and they die at
the end of the first year of their existence.

This order comprises most of the insects more remarkable
for their instincts, such as ants, bees (Fig. 131), and wasps ; to
it also belong the humble bee (Fig. 131), the xylocopes (Fig.

444

ZOOLOGY.

124), the tenthredes, the sirex (Fig. 474), the ichneumon,
the cynips, &c.

§ 543. The order of lepidoptera is composed of insects
whose mouth (Fig. 441) is so formed as to be adapted only

Fig. 470.— Termites (White Ants).

for the drawing up of juices deposited on the surface of
plants; whose wings are four in number, membranous, as in
the two preceding groups, opaque, and variously coloured by

Fig. 471.— Ant.

the presence of a sort of scaly dust fixed to the surface.
The mouth, as we have already said, has the form of a pro-
boscis rolled into a spiral. Finally, these insects undergo a

CLASS INSECTS. 445

complete metamorphosis, and their larvae (Figs. 446, 449,
479, 45), known by the name of caterpillars, are provided
with feet towards the two extremities of their body, and live
generally on leaves ; some envelope themselves in a silky
cocoon in order to complete their transformation ; others roll
themselves into leaves, or suspend themselves to some foreign
body by means of a silken thread.

Fig. 472.— -The Bashikouay Ant.

[This ant, also called NcJtounou by the Mpongwe, is very
abundant in the whole region I travelled over in Africa, and is
the most voracious creature I ever met. It is the dread of all
living animals, from the leopard to the smallest insect. I do not
think that they build a nest or home of any kind. At any rate,
they carry nothing away, but eat all their prey on the spot. It
is their habit t® march through the forests in a long, regular line
— a line about two inches broad, and often several miles in
length. The bashikouay have the sense of smell finely developed.
They are longer than any American ant, being at least half an
inch long, and are armed with very powerful fore-legs and sharp
jaws, with which they bite. They are red or dark brown in
colour. — R. K.]

Amongst the lepidoptera, some fly during the day, others
show themselves only at dusk, and others remain as it were
benumbed during the day, and appear only at night. The
diurnal are known by their wings being elevated vertically
during repose (Fig. 476), and are remarkable for the variety
and brilliancy of their colours. They are generally termed pa-
Dillons (butterflies), but zoologists divide them into vanessae
(Fig. 475), butterflies, properly so called (Fig. 442), danaides
(Fig. 476), &c. The twilight and the nocturnal have the wings

446

ZOOLOGY.

horizontal during repose, and have in general more sombre
colours than the preceding. These are the sphinx (Fig. 477),
the silkworm moths (Figs. 454 and 478), the phalsense, the

Fig. 473. — Bombus, or Humble Bee (Apis muscorum).

tineite, &c. The pyralis (Fig. 479), which occasions also
such destruction to the vineries, "belongs to this group.

Fig. 474. — Gigantic Sirex (Sires gigantea).

§ 544. The hemiptera also have the mouth formed for
suction, not consisting in a single proboscis, but with the

CLASS INSECTS.

447

form of a bill or beak, in the interior of which are sharp
stylets, adapted to perforate animal or vegetable tissues, in
which the animal finds the liquids by which it is nourished

Fig. 475. — Peacock Butterfly (Vanessa io).

, like all the

(§ 523). These insects have generally four wings, like a
preceding, but usually those of the first pair are only :
branous towards the extremity, and constitute semi-elytra.

Fig. 476. — Danais Plexippa ; a species of Butterfly.

Finally, the metamorphoses are incomplete, and the insect as
it grows changes neither its form nor its habits ; only it in
general acquires wings, which it had not at first ; sometimes,

448 ,! ZOOLOGY.

however, they retnain without these organs. This is the
case with the bed bugs, for example. We arrange in this
order the pentatoma, the halys pr wood bug (Fig. 480 and

Tig. 477,— Sphinx of the Vine.

481) &c., the nepas or water flea (Fig. 484), the cigale or
balm cricket (Fig. 482), the pucerons, the cochineal, &c.
We may also bring near to this group the flea (Fig. 483), for

Fig. 478.— Oak-Leaf Moth,

CLASS INSECTS.

449

example, which is always apterous, like the bug, and which
has been considered by most naturalists entitled to form a
particular order, called suckers.

§ 545. The order of diptera is characterized by the exist-
ence of a single pair of membranous wings, not unlike those
of the hymenoptera, and by the structure of the mouth,

Fig. 479.— Pyrales of the Vine; Caterpillar of the Vine Moth.*

arranged for suction only ; we observe in it in general a pro-
boscis, sometimes horny and elongated, sometimes soft and
retractile, and inclosing stiff and sharp bristles.

A sufficiently correct idea of the general form of dipterous
insects may be derived from one of them known to all the
world — the common fly; and we shall only add, that all un-
dergo a complete metamorphosis. The larvsB (Fig. 486, a)
have no limbs ; their head is soft, and the mouth is generally
provided with hooks. Sometimes they change the skiii
several times, and spin a cocoon, to transform themselves in
it into a nymph j at other times they do not moult, and their

* Leaf of the vine attacked by the pyrales : — 4, the male ; 4a, the female
46, the caterpillar ; 4>c, the eggs ; 4d and 4<e, the chrysalides.
G G

150

ZOOLOGY.

skin, hardened and horny, becomes for the nymph a solid
cocoon, having the appearance of a seed (Fig. 486, a).

In this division we place, in addition to the flies, properly
so called, the gnats, the gad-fly (Fig. 487), the oestrus (Fig.
486), &c.

Pig. 480.— Peutatoraa (Cimex ornatus). Fig. 481.— Halys, or Wood Bug.

§ 546. The rhipiptera are insects having also but two
wings, but in which the organs are folded longitudinally, like
a fan ; two genera only are known, the stylops (Fig. 490) and
the xenos, which in their state of larva live as parasites on
the abdomen of wasps and other hymenoptera.

Fig. 482.— The Balm Cricket.

§ 547. The order anoplures or parasites is not numerous,
and is composed of insects which are always without wings,
which have the mouth arranged for suction, and which do

CLASS INSECTS,

451

not undergo a metamorphosis. As indicated by their name,
they live on the bodies of other animals, whose veins they
suck. They form two genera, the pediculus (Fig. 49J ), and

Fig. 4S3.— The Flea. Fig. 484.— The Nepa. Fig. 485.— The Bug.
Water Scorpion.

Fig. 486.— (Estrus, or
Bat-fly.

Fig. 487.— The Ox-fly, or Gad-fly.

Fig. 488.*

* 1. The Ligurian Bee (apis ligustrica) ; 2. the Banded Bee (apis fas-
ciata) ; described by M. Isidore Geoffroy St. Hilaire.— K. K.
G G 2

452 ZOOLOGY.

the riccinus ; these last attach themselves to the dog and to
various birds.

Natural size.
Fig. 439.— The Tsetse-fly.

[The tsetse fly ;• copied from Dr. Livingstone's work on South
Africa, p. 571. The following interesting account of this remark-
ably destructive fly is taken from the work of the celebrated
traveller alluded to.

<l The tsetse is not much larger than the common house-fly,
and is nearly of the same brown colour as the common honey-bee;
the after part of the body has three or four yellow bars across it ;
the wings project beyond this part considerably, and it is remark-
ably alert, avoiding most dexterously all attempts to capture it
with the hand at common temperatures ; in the cool of the
morning and evening it is less agile. Its peculiar buzz, when
once heard, can never be forgotten by the traveller whose means
of locomotion are domestic animals ; for it is well known that
the bite of this poisonous insect is certain death to the ox, horse,
und dog. In this journey, though we were not aware of any
great number having at any time lighted on our cattle, we lost
forty-three fine oxen by its bite. We watched the animals care-
fully, and believe that not a score of flies ^were ever upon them.
A most remarkable feature in the bite of the tsetse is its perfect
harmlessness in man and wild animals, and even calves, so long
as they continue to suck the cows. We never experienced the
slightest injury from them ourselves, personally, although we lived
two months in their habitat, which was in this case as sharply
defined as in many others, for the south bank of the Chobe was
infested by them, and the northern bank, where our cattle were
placed, only fifty yards distant, contained not a single specimen.
This was the more remarkable, as we often saw natives carrying
over raw meat to the opposite bank with many tsetse settled
upon it."

CLASS INSECTS.

453

The history of this singular and most destructive insect cannot
fail to excite deep reflections in the mind of the reader, as show-
ing by what apparently insignificant means, entire races of
valuable animals may be destroyed. Many wild species of the
equine family and of the buffalo exist in Southern Africa, and
live with impunity, unscathed by the tsetse, the attacks of which
prove so fatal to certain domestic animals. The ass, though
domestic in a senee, is not injured by the tsetse ; so also with the
buffalo, and seemingly. all the species of antelope. Sheep also
are safe from its attacks. — K. K.]

Fig. 490.— Stylops.

Fig. 491. — Pediculus humanus,
or Louse.

Fig. 492.— Machilis.

§ 548. Finally, the insects of the order thysanura com-
mence equally with the form which they preserve through
life, and are always without wings ; but they are distinguished
from the preceding by their masticatory apparatus, and by

454 ZOOLOGY.

the appendages with which their abdomen is provided. These
are the podurellse (Fig. 430), the lepisma, machilis
592), &c.

CLASS OF THE MYKIAPODA.

§ 549. The myriapoda (many feet) respire air by means
of tracheae, like insects, but they differ considerably from these
animals, as well as from the arachnides (spiders), by their
general conformation. Not only they never have wings, but
their body, much elongated and divided into a great number
of rings, carries on each of these segments at least a pair of
limbs, besides the number of these organs, always twenty-four
at least, or more ; nor is there any line of demarcation between
the thorax and the abdomen. They somewhat resemble ser-
pents, or worms with feet ; but their internal organization
brings them nearer to ordinary insects, excepting that their
circulatory system is much less incomplete.

Fig. 493.— lulus ; Millipede.

The head of the myriapoda is provided with two small
antennse, and with two eyes, generally farmed by the reunion
of ocelli. Their mouth is formed for mastication, and is pro-
vided with a pair of bi-articulated mandibles, followed by a
sort of lip with four divisions, and with two pairs of appen-
dages resembling little feet. The number of the rings of their
bodies varies, and sometimes these segments appear re-united,
two and two, in such a way that each moveable segment carries
two pairs of limbs (Fig. 493). These last organs terminate
only in a single hook. Finally, there exists on either side of
the body a series of stigmata, in communication with trachea?,
formed in the same way as those of ordinary insects. The
myriapoda experience metamorphoses in youth, but these

OF THE CLASS ARACHNIDA. 455

changes are not analogous to those we have seen take place
in insects properly so called, and consist only in the forma-
tion of new rings, and in a corresponding augmentation in the
number of the limbs.

§ .550. Two natural groups, easily distinguished by the
form of the antennae, compose this latter class — namely, the
chilognathus or iulus, and the chilopodes or scolopendra.

Fig. 494. — Poly desmus, Lat. lulus complanatus, Fab.
Flattened millipede.

The chilognathi have a cylindrical body, and feed on organic
matters more or less decomposed ; their pace is slow, and they
often roll themselves into a spiral or ball. They are known
by the names of iulus (Fig. 493), polydesmus (Fig. 494), and
of glomeris.

The chilopoda have the body flattened and more membra-
nous than the preceding ; they are carnivorous, and run very
fast. Three principal genera compose this group : the scolo-
pendra (Fig. 164), the lithobius, and the scutigera.

OF THE CLASS ARACHNIDA.

§ 551. The class of the arachnida is composed of articu-
lated animals, having a strong analogy with insects, and, like
them, organized to live in air, but which maybe distinguished
at once by the general form of the body, and by the number
of their limbs ; they differ also from those animals in several
important particulars as regards their internal structure. In
fact, all the arachnida have the head confounded with the
thorax, and have no antennae ; they have four pairs of limbs,
and never wings ; and they breathe in general by means of
pulmonary cavities, and have all a tolerably complete circu-
latory apparatus.

§ 552. The tegumentary skeleton of these animals is in

456

ZOOLOGY.

general less solid than that of insects, and their body is com-
posed of two principal parts, almost always distinct ; the one
called cephalothorax, because it is formed by the head and
thorax confounded into a single segment ; the other named
abdomen, and composed sometimes of a series of distinct

Fig. 495. — Mygale, Cuv. Aranea avicularia, Lin. ; Crab Spider.

rings, as may be seen in scorpions (Fig. 499) ; sometimes of a
soft mass, globular, and without divisions, as, for example, in
spiders (Fig. 495).*

•* The arachnides are divided into two orders, the pulmonaria and the
trachearia. The first includes such genera as the aranea, the tarantula,
scorpio, &c. The second order includes the phalangida, with its various
orders of siro, trogulus, &c., and the acarus, of which there are many sub-
genera and species. — B. K.

OF THE CLASS AEACHNIDA. 457

The organs of locomotion are all fixed to the cephalo-
thorax, and consist of eight pairs, strongly resembling those
of insects, and almost always terminated by two hooks ; their
length is in general considerable, and they easily break ; but,
as in the Crustacea, the stump, after having cicatrised, repro-
duces a new limb, which increases by little and little, and
ends by becoming similar to that of which the animal had
been deprived. The arachnida never present even the ves-
tiges of wings, and their abdomen is always completely de-
prived of locomotive appendages.

§ 553. It is in the anterior part of the cepha-
lothorax that we find the mouth and the eyes.
These latter organs are always simple, and in
considerable number ; we generally find eight of F. 496
them (Fig. 496), and we observe in each of them
a transparent cornea, behind which is a crystalline humour
or lens, and a vitreous humour, then a retina, formed by the
termination of an optic nerve, and an envelope of colouring
matter. We find nothing in respect of the instruments by
which the arachnida ascertain the presence of sounds, but we
have many proofs of the existence of this sense in these
animals, and it would even appear that some of them are
sensible to the charms of music. Touch is exercised chiefly
by the extremity of the limbs, and by the appendages with
which the mouth is provided.

§ 554. The nervous system of the arachnida presents
differences sufficiently remarkable; sometimes, as in the
scorpions for example, it is composed of a series of nine
ganglionary masses, reunited together by double cords of
communication, and forming a chain extending from one
extremity of the body to the other, and in an almost uniform
manner ; at other times, as in spiders, &c., we find all the
ganglions of the thorax united into a single mass (t, Figs.
497 and 500), whence proceed backwards two cords (c), which
proceed to terminate in a single abdominal ganglion (a, Fig,
500). Further, the general disposition of these parts is
always the same ; the anterior ganglions (c), situated in
front of and above the gullet, and considered most generally
as representing the brain of these animals, give origin to the
optic nerves anteriorly, and are continuous behind with the
cesophagal collar ; the other ganglions are situated under
the alimentary tube, and send nerves to the limbs, abdo-
men, &c.

458

ZOOLOGY.

§ 555. The arachnida are carnivorous, but confine them-
selves generally to suck the humours contained in the dead
body of their victim ; and in order to render easy the capture
of animals whose strength they might dread, nature has pro-
vided a great many of them with a venomous apparatus.
Most of them feed on insects, which they seize alive ; some,
however, are parasites. In the first, the mouth (Fig. 498)
is furnished with a pair of mandibles, armed with move-
able hooks, or formed like forceps of a pair of lamellated
jaws, having each a large feeler more or less pediforin, and
some of a lower lip ; in the parasite arachnida, the mouth has
the form of a small proboscis, whence springs a kind of lancet
formed by the jaws.

ca t ce b ma m y

Fig. 497.— Nervous System, &c.*

The moveable hook or claw of the mandibles has near its
extremity a small opening, which is the orifice of the excre-
tory canal of the venomous gland already spoken of, and the
liquid which it pours into the bottom of the wound causes
immediately the benumbing of the insects which these ani-
mals pursue, but is too feeble to injure man, and it is without
any reason that the common people often ascribe to the bite
of spiders the pimples and red spots which sometimes appear
on the skin.

* Section of the cephalothorax of the Mygale (crab spider) , showing the
disposition of the nervous system : — ct , cephalothorax ; m, mandible ; g, claw
or moveable hook terminating it ; 6, mouth; ce, the gullet ; e, the stomach;
ab, origin of the abdomen ; c, brain or cephalic ganglion ; t, ganglionary
mass of the thorax ; ca, cords uniting the abdominal ganglions ; no, optic
nerve ; y, the eyes.

OF THE CLASS ARACHNIDA. 459

Certain arachnida are provided with another venomous
apparatus destined for the same purpose, and also serving as
defensive weapons, — such as the hook or claw which ter-
minates the ahdomen of scorpions (Fig. 499). This sting
presents underneath the point several openings which com*
municate with the venomous glands, and the sting of these
arachnida is often mortal, even to animals of considerable
size, as the dog. The great scorpions of hot countries are
also much dreaded hy man, but
the sting of the species inhabiting
Europe would seem never to be j
mortal; there generally arises a
local inflammation, more or less
acute, accompanied with fever and
stupor, sometimes vomitings and mt
tremblings, as the result of such
a wound. To overcome these
symptoms, medical men recom- ris- 498-*

mend the use of volatile alkali,

given internally as well as applied externally to the wound ;
emollient substances are also applied to the wound.f

The intestinal canal is in general very simple, but is some-
times complicated, with csecal appendages which penetrate
even into the interior of the limbs.

In general, tubes analogous to the biliary vessels of insects
open into the intestines near the anus ; but in some arach-
nida, such as scorpions, there exists also a liver, composed of
four glandular branches.^

It is also around the anal opening that we find the secret-
ing glands of the silky matter, and the winders by the aid
of which several arachnida construct webs, which are often of
great extent and of extreme fineness (Fig. 500).

§ 556. The respiration of the arachnida is aerian, and
takes place sometimes by means of tracheae ; but in most of

* Buccal apparatus of a spider: — s, the sternum; I, the lip; ma, jaws;
p, palpi of the jaws ; m, mandibles ; g, hooks or claws of the mandibles,
t In Southern Africa, and on the banks of the Great Fish River, I ob-

. they pro
strong spirits. — R. K.

% These animals are numerous beyond imagination in Southern Africa, on
the banks of the Great Fish River. I remember a large plain covered with
small flat loose stones, underneath each of which there seemed to reside a
scorpion ; for of the hundreds turned over, we never failed to find one. They
were also always solitary. This was at the post of Wenzel Koosters.— R. K.

460 ZOOLOGY.

these animals, especially in spiders and scorpions, it is con-
centrated in pouches lodged in the ahdomen, and called
lungs. These latter organs present internally a number of
membranous lamellae (I, Fig. 500), arranged like 'the leaves
of a book ; thus, they more resemble branchia3 than true
lungs. Each lung receives the air by an opening situated in
the lower aspect of the abdomen (s), and sometimes two such
may be counted, sometimes four, and sometimes eight.

Certain spiders possess at the same time lungs and tracheae,
such as the segestries ;* and others, as the faucheur and
the mites, have tracheae only. These tubes have the same
structure as in insects, and the air enters them by two very
small stigmata situated at the lower part of the abdomen.

Fig. 499.— The Scorpion.

The blood is white in all animals of this class. The pul-
monary arachnida have a circulatory apparatus sufficiently
complete. Their heart (Fig. 501), situated in the back, has
the form of an elongated vessel, and^ gives origin to various
arteries ; the blood, after having traversed the organs, pro-
ceeds to the lungs, and from thence reaches the heart,
following a course similar to that which we have already
seen takes place in the Crustacea (§ 111). In the arachnida
which breathe only by tracheae, the apparatus of the circula-
tion is rudimentary. There appears to be merely a simple
dorsal vessel without arteries or veins.

§ 557. The arachnida lay eggs like insects, and the male
differs generally from the female in the form of the maxillary

* Sub-genus segeatria. Lat. Example of species : Aranea florentina,
Koss.-R?K.

OF THE CLASS ABACHNIDA.

461

feelers, the uses of which appear to be very important. A
great number of these animals envelope their eggs in a
cocoon of silk, and sometimes the mother remains near her
young family to protect it, and even carries the little ones on
her back when they are too feeble to walk alone. All these
animals undergo several moultings before reaching the adult

pa -

Fig. 500.— Anatomy of a Mygale.*

age, and some experience a sort of metamorphosis ; for there
are of them whose limbs at first are only three pairs in num-
ber, but which acquire a fourth at a more advanced age.

* [Aranea avicularia : Crab Spiders. I have seen them very large in South
Africa. — R. K.] ct, cephalothorax open below, and giving attachment to the
limbs, the base of which is in place ; pa, limb of the first pair ; p, feeler ; mt
mandibles ; al, abdomen ; t, thoracic ganglionary mass ; a, abdominal gan-
glions ; po, pulmonary pouches ; s, stigmata; I, respiratory lamellae of one
of its cavities, laid open ; o, the ovaries ; or, orifice of the oviducts ; ma,
muscles of the abdomen ; an, anus ; f, spinnerets.

462

ZOOLOGY.

§ 558, The arachnida have varied instincts no less remark-
able than those of insects ; and one feels inclined to accord to
them still higher faculties, for animals of this class have
been seen capable of a kind of education, and to give signs of
a sort of intelligence. Many amongst them have recourse to
particular tricks to secure their prey, and others display in
the construction of their dwelling a singular industry. We
have already had occasion to speak of the remarkable nest of
the mygale (Fig. 120) ; the webs which the garden spiders
stretch with an admirable regularity are equally curious.
The silk with which these animals
thus construct their retreats, stretch
snares for their prey, and form cocoons
for their eggs, is secreted by an ap-
paratus lodged in the posterior part
of the abdomen. This apparatus
consists in several packets of vessels,
turned on themselves, and terminat-
ing in pieces pierced at the summit
of four or six conical or cylindrical
mamelons called winders, and situated
under the anus (Fig. 500). The gluey
matter expelled through these pores
acquires consistence by the contact
of the air, and forms threads of ex-
treme tenuity, and of a very great
length. By the aid of its limbs the
animal reunites into a single cord a

multitude of these threads, and each time that, in balancing
itself, these winders come to touch the body on which it
rests, they attach to it the extremity of one of these threads,
the opposite end of which is still eselosed in the secretory
apparatus, and the length of which it may consequently
augment at pleasure. The colour and the diameter of the
thread, varies much : a spider of Mexico constructs a web
composed of red, yellow, and black threads, interlaced with
remarkable art ; and it has been calculated that ten thousand
threads, as they come from the pores of one of the winders of
some of our common spiders, do not equal in thickness one
of our hairs ; whilst other species, peculiar to hot countries,
form nets so strong that they suffice to arrest the progress

* Abdomen and Heart of a Spider : — a, abdomen ; c, heart ; ar, cephalic
artery ; v, venous canals.

OF THE CLASS ARACHNIDA. 463

of small birds, and even man himself is obliged to make an
effort to break through them. The manner in which spiders
arrange their silk is no less varied : some confine themselves
to stretch irregular threads, and others weave a web the
messes of which are of extreme regularity. Sometimes we,
see them immovable in the middle of their web, watching
their prey ; at other times, they conceal themselves in a
retreat which they construct at hand, and which sometimes
has the appearance of a silky tube, sometimes that of a small
cup or cupola.

§ 559. The araclmida are divided into two orders, accord-
ing to the structure of the organs of respiration and of circu-
lation.

The arachnida pulmonaria are chiefly characterized by the
presence of pulmonary pouches and of a well developed vas-
cular apparatus ; but they may also be recognised by other
peculiarities of structure. Thus, their
eyes are six, eight, or even more in
number, and under the abdomen may
be seen two, four, or eight stigmata.
Moreover, the general form of these
animals varies. Sometimes they have
the abdomen globular, winders at its ex-
tremity, and small mandibular feelers ;
at other times the abdomen is elongated
and composed of several rings ; their
mandibular feelers advance like arms,
and terminate like forceps ; or finally,
there exist no winders at the extremity
of the body, but in general a venomous
apparatus. Spiders properly so called
(Fig. 174), that is to say, the mygale
(Fig. 495), the epeira, the lycosse or tarantulse, the theridions
(Fig. 502), present us with the first of these two modes of
conformation ; the scorpion (Fig. 499), the second.

§ 560. The arachnida trachearia have no pulmonary
pouches, but respire by tracheae, like insects, and have
only a rudimentary vascular apparatus for the circulation of
the blood. Some are without eyes, and in those which have
them, we never find more than two or four. Some of these
animals, known by the name of faucheurs, greatly resemble
spiders, and are remarkable for the length of their limbs ;
others have the mouth formed for suction, and constitute the

464 ZOOLOGY.

family acari or mites ; they are very small, and several live
as parasites on other animals. One species, the ixodes of
Brazil, fixes itself on dogs, oxen, &c., and so deeply plunges
its suckers into the flesh of these animals, that they cannot
be detached without raising up the portion of the skin to
which they adhere. It is asserted that the multiplication of
these parasites is sometimes so considerable as to cause the
death of the oxen and horses to which they have fixed them-
selves, by exhaustion.* Another kind of mite, called leptus
autumnalis, or rouget, is very common in the autumn in our
fields, and, insinuating itself under the skin of the legs,
causes insupportable itchings. Finally, it is a small animal

Fig. 503.— Sarcopt of the Psora (magnified) ; Itch Insect.

of this family which, by multiplying in winding burrows
under the skin, occasions one of the most disgusting diseases,
the Psora, or Itch. The sarcopt of the Psora (Fig. 503) is
scarcely visible to the naked eye ; but when examined with a
microscope, its body is seen to be oblong, and its mouth to

* Parasitical animals of this class abound in Southern Africa, and I am
aware that they attach themselves indiscriminately to oxen, horses, dogs,
&c., but it seemed to me that they had a predilection for the diseased or
enfeebled animal ; for if by chance an exhausted horse was left on the field
for some days, he became covered with these vermin, whilst they seldom
attached themselves to the healthy, well-fed animal.— K. K.

CLASS OF CRUSTACEA. 465

have the form of a conical papilla armed with several bristles,
and its feet, eight in number, differ very much from each
other, the four posterior feet being terminated only by
bristles, whilst the four anterior feet are furnished at their
extremity with small suckers, by means of which they can
adhere to the most polished bodies.

CLASS OF CRUSTACEA.

§ 561. The Crustacea are articulated animals properly
so called, having the respiration branchial or only cutaneous,
and a circulatory apparatus semi-vascular and semi-lacunar.
The crabs, craw-fish, and lobsters (Fig. 504), form the type
of this group, but naturalists arrange in it also a great
number of animals whose structure is much less complex,
and whose external form is different ; for in proportion as we
descend in the natural series of these animals, we find the
general plan of organization to be successively modified and
simplified more and more. The lowest of the Crustacea are
even so imperfect, that they can only live when fixed as
parasites on other animals, and most naturalists have
arranged them with the intestinal worms.

§ 562. The tegumentary skeleton of the Crustacea presents
in general a very considerable consistence. It has almost
alwajrs a stony hardness, and encloses, in fact, a considerable
portion of the carbonate of lime. One may view this solid
envelope as being a kind of epidermis, for beneath it we find
a membrane (t, Fig. 513) resembling the dermis of superior
animals ; and at certain points the hard calcareous envelope
is detached and thrown off', as we have already seen the
epidermis of reptiles separate itself from the body, and
the tegumentary membrane of the larvae of insects moulting
or renewing itself several times. It is easy to understand
the necessity of these moultings in animals whose whole
body is enclosed in a solid case, which, as it cannot grow
proportionately with the interior structures, would present
insurmountable obstacles to their development if it did not
'fall or was thrown off at the moment when it became too
small to lodge the body conveniently; thus the Crustacea
change their external covering during the entire period of

H H

466

ZOOLOGY.

their growth, and it would appear that most of these animals
increase in size during the whole of their lives. The manner

Fig. 504.— Ihe Lobster.

in which they throw off their old covering is very singular ;
in general they contrive to leave it without causing the

CLASS OF CRUSTACEA. 467

slightest deformation, and when they quit it the whole sur-
face of their body is already covered with a new sheath ; hut
this is still soft, and only acquires its necessary solidity at
the end of some days.

The bodies of Crustacea are composed of a series of rings
more or less distinct. Sometimes the most of these segments
are simply articulated with each other, and have a tolerably
wide range of mobility. Sometimes they are all united to-
gether, and can be distinguished only by grooves at the points
of junction. Finally, at other times, their union is still
more complete, and it is only by analogy that the zoologist
is induced to consider the segment resulting from their fusion
as composed of several rings rather than one. There results,
as might he expected, very wide differences in the general
form of these animals ; and if we

compare together a cloportes (Fig. ^^-^ /

505) or wood louse, a talitrus
(Fig. 169),* and a crab (Fig. c
506), for example, one might be tl
led at first sight to believe them
to be constructed on wholly diffe-
rent types; but a deeper study
of their structure shows that the
composition of their tegumentary *'
skeleton is essentially the same,
and that the differences depend on
this, that the greater number of
the rings, completely distinct and Fi£- 505'^^le^0niscus)>
moveable in the oniscus, are

united to each other in the crabs, and that certain analogous
parts do not present in these two genera the same proportions.
Thus, in the oniscus (Fig. 505) or in the talitrus (Fig. 169)
we find a distinct head (c), followed by a thorax composed of
seven rings, resembling each other (tl, t7), and carrying each
a pair of limbs (p, pp) ; finally, at the posterior part of the
body we find an abdomen (ab), formed also of seven segments,
whose size diminishes rapidly, but whose form is nearly the
same as in the thorax. In a crab, on the contrary (Fig. 506),
the head is not distinct from the thorax, and forms with all
this section of the body a single segment covered with a large
solid buckler, named shell, or carapace ; finally, the abdomen

* Oniscus locustra; talitrus: Lat. Of the genus Grammarina; family
Gammarus ; band-hopper.— K. K.

H H 2

468

ZOOLOGY.

at first escapes the sight, because it is folded under the thorax,
and is but small. Nevertheless, it is easy to demonstrate
that in the crab, as in the oniscus, there exist behind the
head seven easily recognisable thoracic rings, and that the
carapace is not a new organ created for the former, but
merely the dorsal portion of one of the rings of the head
which has acquired an extreme development, and encroached
on the neighbouring rings, In other animals of the same
class, the general form of the body is removed still further
from those of which we have just spoken. Thus the lim-
nadise are enclosed between two oval bucklers, united to-
gether after the manner of the valves of the oyster; and it is
after having removed this moveable cuirass, that the true
annulated structure of their bodies is observed (Fig. 519) ;

Fig. 506.— The Crab (Maia) • Sea Spider.

the cypris, abounding in stagnant waters, presents an analo-
gous disposition, only the rings of which their bodies are
composed are still more difficult to be recognised. Finally,
we may cite the lernsea, which at the adult age presents the
strangest forms (Fig. 155, 156), but which when young has

BASIS OF THE TEANSCENDENTAL. 469

a distinctly annulated structure (§ 366). This comparative
study of the tegumentary skeleton of the Crustacea presents
a great interest, in respect of physiological anatomy, of which
one of the most important branches is to investigate the
modifications which nature causes the same organic elements
to undergo, to adapt them to various uses, and to create with
analogous or homologous materials dissimilar instruments ;
but the limits we have assigned to these lectures do not
admit of our touching at greater length on this subject.

[The question here mooted by my friend M. Milne Edwards em-
braces nearly the whole question of the transcendental anatomy,
the only view in which anatomy and zoology become a science.
The following observations, reprinted from my work on the
Races of Men, will sufficiently explain this to the reader : — *

*' By dissection the dead are analysed or reduced to certain
assemblages of organs, holding relations, often mechanical, to
each other. They all perform certain functions, some of which
have been imperfectly guessed at ; made out in a coarse way :
organs of locomotion exist — bones, ligaments, joints, muscles, or
flesh ; organs of sensation, and thought, and will ; the brain and
spinal marrow ; the nerves ; organs of digestion and assimilation,
the stomach and digestive tube, and their appendages ; lastly,
organs of breathing, essential to life ; the lungs, by which we
draw from the air the breath of life. Bloodvessels acted on by a
heart carry the blood through the frame. Out of this vital fluid the
body is constructed, repaired, and formed. Now if we select any
one of these organs, or sets of organs, we shall find that, in one
shape or another, it extends through the whole range of vertebrate
animals, most probably through the entire range of animal life,
but under a shape or form no longer recognisable by our senses.
A few instances will suffice to explain this. There is no occasion
for any minute or technical exposition of facts, which are, as it
were, on the surface. Let us first turn our attention to the
skeleton. Not that this assemblage of levers proves better than
any other set of organs the unity of structure, the unity of orga-
nization sought 'to be superadded by the German and Sclavonian
philosophy, to the unity of plan laid down by Newton ; I do not
even think so well ; but it presents materials easier to be handled,
easier to be inspected, obtained, and understood.

"The basis of the skeleton, whether mere animal or man, is a
series of bones jointed or articulated with each other. In common
language it is called the back bone. You see how violently in-

* See the Races of Men ; a Fragment. By K. Knox. Henry Eenshaw,
London. This work was originally delivered in the form of Lectures. —
It. K.

470 ZOOLOGY.

accurate such a term is, when applied to a series of bones per-
fectly distinct from each other, possessing most of them a distinct
mobility. These bones we call vertebrce ; here is one of them.
When studied by the surgeon or medical man, it is viewed by
him merely as a portion of the skeleton : to the philosophic
anatomist it becomes the type of all vertebrate animals, of the
entire skeleton, limbs and head included ; ©f the organic world,
vertebrate and invertebrate. Carried further, it possesses the
form of the primitive cell ; of the sphere ; of the universe.

"Now look at this bone in man — it appears simple, but it is
not so. Originally, that is, in the young, composed of many
distinct portions, which afterwards unite with each other, but
which remaining distinct in many animals, as in fishes, proves
to us, that throughout the whole range of animals so formed, the
vertebrae do not really differ so much from each other as might
at first appear : that, in fact, the elements forming them seem
the same almost numerically, giving rise to the well-grounded
belief, that, in the embryo, the elements of the skeleton may be,
after all, the same in every animal. From man to the whale, all
is alike; one theory explains all; one idea or plan pervades all.

" Let us trace this chain of bones upwards and downwards ;
see how downwards (coccygeal vertebrae) certain elements cease
to be developed, or do not grow : still the plan is the same ;
identical ; analogous, as regards the individual, that is, repeated ;
homologous or identical, as regards one animal compared with
another. Look to this section of the skeleton, called the head ;
the bones seem widely different from the vertebrae ; but it is not
so. They are merely vertebrae, repeated, upon a larger scale as
may be required : a chain of vertebra form, then, the head or
cranium. These great truths we owe exclusively to the illus-
trious South German and Sclavonian schools of transcendental
anatomy ; to Oken and Spix, Autenrieth, Frank, Goethe, and a
host of others. * * *

"A vertebra must have a type; thaj. is, a plan sufficiently
comprehensive to include all forms of vertebrae. Now where is
this to be found ? Is it an ideal type not yet discovered ? Or is
it to be found in any extinct or living animal ? I apprehend that
it may or it may riot have been found, but this in no way inter-
feres with the principle that there must be a type laid down by
nature ; eternal ; equal to all manifestations of form, extinct or
living, or to come.

" But the discovery of such a type could only be made were
the anatomy of all animals that ever lived known to us ; perhaps
not even then, for the future must be wrapt up in the past : and
what seems to us now a mere speck of bone, a nucleus, a point,
unimportant, nay, scarcely discernible, may, in a future order of
things, become an all-important element. As thus : —

BASIS OF THE TRANSCENDENTAL. 471

"If birds did not exist, we could scarcely conceive the high
organization to which the third eyelid, in man a mere rudiment,
attains in them. Not wanted in man, the organ sinks to its
rudimentary and scarcely perceptible condition. Of essential
service in birds, it suddenly acquires its seemingly highest deve-
lopment. Yet the organ was always present, rudimentary in
one, developed in the other. Let us take another instance.

' ' The adult, or grown-up man, has, as you all no doubt know,
three bones to each toe, with the exception of the first ; these
three bones are connected to each other, and to the metatarsal
bone, their supporters, by three joints. In the feet of birds you
meet with four or five bones in certain of the toes ; and it might
seem to you that the feet of birds were formed on a different
numerical plan at least ; but it is not so : for in man, as in
birds, each digital bone is formed of two elements, or distinct
bones, at first, that is, in the young of each : as the bird grows
up, they remain distinct — in man, on the contrary, they unite —
that is all. The arrangement is not only analogous, but homo-
logous or identical, in the strictest sense of the terms.

** Again, remember that a thousand similar instances might
be given : I merely select a few of the easiest understood.

1 ' In man there is a little cartilage, scarcely perceptible, con-
nected to one of those bones occupying the nostrils, called turbi-
nated bones. It may or it may not in him serve any purpose ;
that is a matter of pure indifference. It is a rudimentary and a
useless organ seemingly. Now, mark the extension and develop-
ment of this cartilage or organ in the horse — still more in the
whale ; in the horse, where it most admirably serves to shut off
the great cavities of the nostrils from the vestibular cavitiis in
front — thus protecting them from foreign bodies : in the whale,
acquiring their presumed highest development, these cartilages,
now grown to the size of bolsters, return after breathing, into
the vast nostrils of the whale from which they had been momen-
tarily withdrawn, filling them up, sealing them hermetically
against the pressure of a thousand fathoms deep of water, which
they sustain with ease, when, plunging into the vast abyss of the
ocean, the giant of nature seeks to avoid his enemies.

" Let us now briefly review the progress we have made in this
the highest of all analyses : deepest of all theories : most im-
portant to man. Man, we have seen, stands not alone, he is one
of many ; a part and parcel of the organic world, from all eternity.
That organic world is the product of secondary causes. During
his growth he undergoes numerous metamorphoses, too numerous
even for the human imagination. These have a relation to the
organic world. They embrace the entire range of organic life,
from the beginning to the end of time. Nature can have no
double systems ; no amendments or second thoughts ; no excep-

472 ZOOLOGY.

tional laws. Eternal and unchanging, the orbs move in their
spheres precisely as they did millions of years ago. Proceeding,
as it were, from an invisible point endowed with life, he passes,
rapidly at first, through many forms, all resembling, more or
less, either different races of men from his own, or animals lower
in the scale of being ; or beings which do not now exist, though
they probably once did, or may at some future time. When his
development is imperfect, it represents then some form, resembling
the inferior races of men, or animals still lower in the scale of
being. Moreover, what is irregular in him is the regular struc-
ture in some other class of animals. Take, for example, the
webbed hand or foot occasionally found in man, constant in
certain animals — as in the otter and beaver ; constant also in
the human foetus, that is, the child before birth. Take, for
example, the cuticular fold at the inner angle of the eye, so
common with the Esquimaux and Bosjesman or Hottentot (the
corresponding yellow races of the northern and southern hemi-
spheres), so rare in the European, but existing in every fcetus of
every race. Nor let it be forgotten that forms exist in the human
fcetus which have nothing human in them in the strictest sense
of the term ; that the fcetus of the Negro does not, as has been
stated, resemble the foetus of the European, but that the latter
resembles the former, all the more resembling the nearer they
are to the embryonic condition. Unity of structure, unity of
organization, unity of life, at the commencement of time, whether
measured by the organic world or by the duration of individual
life." This is the law.

The relation of species to genus also merits our deepest atten-
tion.*

"My first observations were made on animals low in the scale
of the vertebrata, — on fishes, in fact. I selected, as I shall
presently more fully explain, the natural family of the Salmonidse,
as the one to which I had given most attention. In the young
of the true salmon I found the specific characters of all the sub-
families of the genus present ; that is, reel spots, dark spots of
several kinds, silvery scales, proportions, and a dentition iden-
tical. The young fish before me was, in fact, a generic animal,
including within it the specific characters of all the species com-
posing the natural family. To connect this generic animal with
any species, you have but to imagine the disappearance of certain
characters then and there present. Nothing requires to be added.
Take, for example, the dentition — the dentition of the vomer, to
which M. Valenciennes attaches so much importance, and in
which he has endeavoured to discover the true distinguishing

* See " Memoirs on the Philosophy of Zoology," in The Zoologist.
Voorst, London; and in the Lancet, 1855. — E. K.

J. Van

EELATION OF SPECIES TO GENUS. 473

characters of the three sub-families into which that distinguished
naturalist subdivides the Salmonidse. Look at these vomerine
teeth in the young of any of the species— that is, as I view it, in
the generic animal, and in the adult of all the species, that is, in
the animal specialized — and we shall find that the generic animal
possesses a dentition embracing all the characters by which the
fully-developed individuals are afterwards to be recognised. But
it is the young alone which comprises all, combines with the
anterior group of teeth (teeth of the chevron) a double row on
the body of the vomer, which row, becoming in due time single,
characterizes, according to M. Valenciennes, the adult of the
sub-family Forelle, or, disappearing altogether, marks the true
salmon when adult, the common trout growing up with the den-
tition of the generic animal. The primitive type, then, is not
lost, as M. Valenciennes seems to have supposed, but is retained
in one species at least of the natural family. As with the denti-
tion, so with the colorations and proportions : and thus the law
of generation being generic, and not specific, marks the extent of
the natural family, its unity in time and space, the fixity of its
species, the destruction of some and the appearance of others
being but the history, not of successive creations, but of one
development, extending through millions of years, countless as
the stars of the firmament.

Fig. 506a.— The Colt.

" Look now at the colt a few months old as it gambols through
the fields, and say, does it resemble the domestic animal from
which it is sprung, in colour, proportions, movements, attitudes ?
Not in the least. Its colour is a rich deep fawn, to be found
only amongst the wildej in its proportions it resembles the
quagga or zebra, and as it canters along, its rocking-horse motion
and short frisking tail recal to the mind scenes only to be seen

474 ZOOLOGY,

in Southern Africa, on the plains of the Koonap or the slopes of
the Winterbergen, where roams the wild horse, to which this
young of a domestic horse bears the strongest resemblance. The
obvious inference is, that even in animals so high in the scale of
mammals as the solidungula, the young is a generic animal,
including in it the colour, proportions, movements, and habits
of the genus, or natural family, of all its species, wherever placed,
and representing, more especially in this instance, a wild species
of that family, never domesticated nor subdued by man. Even
here, where we should expect specific and other influences to
have told strongly on the product — that is, the young, we find
the generic law to be in full force, and that the young of the
domestic horse resembles a species peculiar to another region of
the earth. The natural family, then, of the solidungula embraces
in the young of each species all the forms which it, the genus,
can or has assumed on the earth. The quagga and the zebra
may become extinct ; but their forms remain in the generic
young t)f whatever species still lives. The fossil horse belonged,
no doubt, to the same family ; as the exterior is lost, the precise
species cannot now be determined. That he belonged to any
species now living I do not believe ; but he was of the family,
and may appear again. Thus the successive appearance of new
forms or species is no new creation, but merely the development
of forms already existing in every natural family. The extinc-
tion of species which has gone on through millions of years has
led some to the belief that nature hastens onwards to the extinc-
tion of life on the globe. It is possible ; but I lean to the oppo-
site opinion, believing that living nature will have no end. That
which has been may be again, the potentiality existing in every
species of every natural family ; and to this creed point the
infinite affiliations of germs, not confined to natural families, but
extending to all that lives. These are speculations on which I
do not enter. Primordial forms are visible in all germs ; the
germs themselves must be eternal.

"If we inquire into the law of generic forms lower in the
scale, as in fishes, to which I have just alluded, we find still
stronger confirmation of the point I now seek to determine. The
natural family of the Salmonidae, as the one with which I am
best acquainted, was that fixed on for the inquiry. Look at the
young salmon when but a few inches in length, and you will find
that in its dentition, colouring, and proportions, it is not & specific
but a generic animal — i.e. it possesses (and is therefore perfect)
all the natural history characteristics of the three sub-families
into which the Salmonidse have been divided. At first, for
example, its dentition is the type of the common trout : as it
grows it assumes the character which we find to prevail in some
of the Forelle, or sea trout. Lastly, it assumes the true s:ilmon

CLASS OF CRUSTACEA.

475

dentition ; but that which especially merits attention is, that the
original type of the generic being is of a character so ample as to
embrace all possible forms which the dentition can assume in
any species of that natural family. Nothing is wanting ; nothing
new appears ; nothing lias to be supplied ; all is foreseen ; all
provided for. To institute a species, all that is required is to
omit, or cause to disappear, or cease to grow, some parts of the
organ or apparatus already existing in the generic being. In
every natural family there is a species which bears, to the generic
animal, that is, to the young, a stronger resemblance than any
other. In the Salnioniflge it is the common trout of fresh-water
rivers, but there may be others. In the Solipeda it seems to be
the quagga of Southern Africa." — E. K.]

pm p* p" fp n

Fig. 507.— Palsemon (Fab.) ; Prawn.*

§ 563. The lateral appendages of the various rings con-
stituting the body are in general very numerous, and present
also considerable differences in their conformation and their
uses, whether we consider them in the various parts of the
same individual, or compare them in distinct species. Those
of the first rings, in general, have relations to the functions
of animal life, and carry eyes or form antennae ; the follow-
ing surround the mouth, and serve for the prehension or the

* a, antennae of the first pair ; ai, antennae of the second pair, or inferior
antennae; I, lamellated appendix covering the base; r, rostrum, or frontal
prolongation of the carapace; y, eyes ; pm, external limb-jaw : p', thoracic
limb of the first pair ; p", thoracic limb of the second pair; fp, false swim-
ming limbs of the abdomen ; «, caudal fin.

476

ZOOLOGY.

division of the food (g, 143, 144) ; those of the middle por-
tion of the body constitute limbs for locomotion, and those
placed still further back have very variable uses, but serve in
general for respiration or reproduction : finally, this long
series terminates generally by one or more pairs of limbs,
arranged to serve as fins.

The head, or rather the cephalic
portion of the body, carries the
eyes, the antennae, and the buccal
appendages < sometimes it is di-
vided into several distinct rings,
as in the squilli or shrimps, for
example (Fig. 515) : although
generally it presents no such sepa-
ration, being formed only of a
single segment, which seems to
represent seven rings, confounded
together. Sometimes it is move-
able, and distinct from the thorax
(Fig. 505) ; at other times, on the
contrary, it is united to this second
portion of the body, which in its
turn is composed in certain species
of rings articulated together, but
distinct ; in others, united into a
single mass.

The antennae are almost always
composed of two pairs, and con-
stitute in general very elongated filiform horns, or what
at least resembles them. The limbs are connected in pairs
with the different thoracic rings; there are frequently
seven pairs: in the cloportes (Fig; 505), the prawns of
rivulets, and the talitri, or sand-hoppers, for example ; but
at other times, as may be seen in the crabs (Fig. 506) and
the craw-fish and lobsters (Fig. 143), their number is re-
duced to five pairs only ; for the appendages, which in the
first case formed the four anterior limbs, are then turned to
other uses, and transformed into organs of mastication. There
exist also very great differences in their structure ; in some
Crustacea they are wholly foliaceous, membranous, and exclu-
sively adapted for swimming- (Fig. 518) ; in others they have
the form of small flexed (like elbows) columns, articulated,
and disposed only for walking ; in others still, besides re-

Fig. 508.— Hippa.

CLASS OF CRUSTACEA.

477

maining adapted for this kind of locomotion, they become
suited to act as so many small spades wherewith to dig the
ei'rth, and in that case they are enlarged and lamellated
towards the extremity (Fig. 508) ; and still, finally, in others,
they terminate in forceps, and become instruments of prehen-
sion, fulfilling at the same time their ordinary functions of
instruments of locomotion (Fig. 143). In the swimming
Crustacea, such as the craw-fish and the lobster (Fig. 504),
the palsemon (Fig. 507), &c., the abdomen presents in general
a considerable development, and terminates by a large fin, so
as to become the principal organ of locomotion ; but in those
intended to walk more than they swim, it is in general very
small, and folded under the thorax : in the crabs, for example,
this portion of the body is reduced almost to nothing, and
constitutes then a moveable apron placed on the lower surface
of the body between the limbs.

Fig. 509. — Nervous System of a Crab : the Maia; Sea Spider.*

§ 564. The nervous system is composed of a double series
of ganglions, situated on the ventral aspect of the body near
the median line. Their number corresponds in general to

* Carapace, laid open : — a, exterior antennae ; ;/, eyes ; e, stomach ; c,
brain ; no, optic nerves ; co, oasophagal collar ; ms, stomato-gastric nerves ;
t, thoracic gangliouary mass ; np, nerves of the limbs ; no., abdominal nerve.

478 ZOOLOGY.

that of the distinct segments of which the body is composed,
and those of the first pair are always lodged in the head or in
front of the gullet, where they constitute a sort of brain
(Fig. 509, c) : but the arrangement of the^ ganglions of the
thorax and abdomen varies much; sometimes they are at
equal distances from each other, and form, with their cords of
communication, a chain extending from one extremity of the
body to the other ; sometimes they approach each other more
or less, and sometimes they are altogether reunited into a
mass situated towards the middle of the thorax (Pig. 509, t).
It oiio-nt also to be observed, that the centralization of the

1 )

Fig. 510.— Podophthalmus ; Stalk-eyed Crab.

nervous system becomes more and more complete in propor-
tion as the animal rises in the scale of being or acquires a
more elevated organization. Moreover, ail the Crustacea
have very limited faculties, and none amongst them present
much interest in respect of their habits. The eyes are formed
pretty nearly as in insects. Sometimes they are simple ; but
generally they are compound or composite, and in all the
more perfect Crustacea they are carried on moveable peduncles
(Fig. 510), an arrangement not found in any of the other
divisions of this great class of articulated animals.

In many Crustacea there exists also an organ of hearing,
situated at the base of the external antennae (Fig. 511), com-
posed of a small membrane resembling a membrana tym-
pani, above which is found a kind of vestibule filled with
liquid, and enclosing the termination of a special nerve.
Nothing is for certain known respecting the faculties of smell
and taste in these animals.

CLASS OF CRUSTACEA. 479

§ 565. Most Crustacea live on animal substances ; but
they offer great differences in their regime ; some live only
on liquid matters, others on solid food, and differences are
observable in the construction of the mouth, corresponding
to their varied circumstances. In the masticating Crustacea
there is before the mouth a short transverse lip, followed by
a pair of mandibles, a lower lip, one or two pairs of jaws pro-
perly so called, and in general one or three pairs of auxiliaries
or lirnb-jaws, serving chiefly for the prehension of the food
(Fig. 144). In the Crustacea which live by suction, we find,
on the contrary, the mouth prolonged into a kind of beak or
proboscis, resembling those insects whose habits are analogous.
In the interior of this tube are slender pointed appendages,
performing the functions of small lancets, and on either side
we find generally organs analogous to the auxiliary jaws of
the grinding Crustacea, but which are formed to enable the
animal to fix on its prey.

Fig. 511.*

§ 566. The digestive canal extends from the head to the
posterior extremity of the abdomen, and is composed of a very
short gullet, a large stomach (e, Fig. 513), armed in general
internally with powerful teeth, a slender intestine, and a
rectum. In some Crustacea, the bile is secreted by biliary
vessels sufficiently resembling those of insects ; but in general
there exists a very voluminous liver (/o), divided into several
lobes, and composed of a number of small tubes, terminating
in a cul de sac, and grouped around a ramified excretory

480 ZOOLOGY.

canal, the extremity of which terminates on each side in the
intestine near the pylorus.

§ 567. Nothing is known of the manner in which the
chyle passes from the intestine into the circulatory apparatus.
The blood is colourless, or slightly bluish or lilac, and
coagulates readily. This liquid is set in motion by a heart
placed on the median line of the back (c. Fig. 427), and
composed of a single cavity. Its form varies, and its con-
tractions drive the blood into the arteries, by which it is dis-
tributed to all parts of the body. The veins are replaced by
the lacunae which the various organs leave between them,
and which are lined b}^ a thin layer of cellular tissue; they
terminate in vast sinuses, situated near the base of the limbs
(s, Fig. 512), and from these cavities the blood proceeds to
the respiratory organs, then returns to the heart by dis-
tinct canals named branchio-cardiac (c b, Fig. 512).

Fig. 512. — Circulatory Apparatus of a Crab.*

§ 568. The Crustacea are almost^all essentially aquatic
animals : thus their respiration takes place almost always by
means of branchiae, and when these organs are wanting,
it is the skin of certain parts of the body (most generally of
the limbs) which takes their place. Thus in the crabs,
lobsters, and all Crustacea of analogous organization, the
branchiae consist of a considerable number of small cylinders,

* Vertical section of the thorax of a crustaceous animal, showing the
course followed by the blood ; c, the heart ; s, venous sinuses ; b, branchiae ;
va, vessel carrying the venous blood to the branchiae ; ve, vessel receiving
the blood after its passage through the capillary network of the branchiae ;
vb, branchio-cardiac vessels ; /, arch of the flancs : &t, sternum ; ce, cellule
of the flancs ; p, base of the limbs.

CLASS OF CKUSTACEA.

481

disposed like the bristles of a brush, or of small lamellse,
piled on each other like the leaves of a book. These organs
are fixed by their extremity to the inferior margin of the
arch of the flancs (Figs. 512 and 514), and are enclosed in

\
/' /

Fig. 513. — Anatomy of the Crab (Tourteau) ; Common edible Crab.*

* The greater part of the carapace has been removed : — t, portion of the
cutaneous membrane lining the carapace ; c, the heart ; ao, ophthalmic
artery; aa, abdominal artery; b, branchiae in their natural position; b',
branchiae, reversed externally, to show their afferent vessels ; Ji, arch of the
flancs ;f, flabelliform appendix, or epignathus of the limb-jaws ; f, stomach ;
m, muscles of the stomach ; fo, the liver.
I I

482 ZOOLOGY.

two large cavities situated on the sides of the thorax, and
comprised between the carapace and the arch of which we
have just spoken, an arrangement which does not occur in any
other animal of this class. The respiratory cavity communi-
cates externally by two openings ; the one serving for the
entrance of the water, almost always situated between the
base of the limbs and the edge of the carapace (r, Fig. 511),
the other, destined for the escape of this liquid, is placed at the
sides of the mouth. Finally, the renewal of the water on
the surface of the branchiae is caused b}' the movements of a

Fig. 514. — Respiratory Apparatus of a Palsemon, or Prawn.*

large valvule situated near this latter,,opening, and formed by
a lamellated appendix of the jaws of the second pair (c, Fig.
144; i, Fig. 514). In other Crustacea, the squillse (shrimps)
for example (Fig. 515), the branchiae have the form of
bunches of feathers, and in place of being enclosed within the
thorax, float freely, externally, and are attached to the abdo-
minal limbs ; in others still, as in the prawns of rivulets and
the talitri, they are formed of membranous vesicles fixed to

* a, rostrum ; b, carapace ; c, base of the antennae; d, base of the abdomen;
e, base of the limbs ;./, branchiae ; g, dotted line, pointing out the inferior edge
of that portion of the carapace which covers the branchiae, and which has
been remored in this preparation ; h, efferent canal of the respiration j i>
valvule ; .;, extremity of the efferent, or expiratory canal.

CLASS OF CRUSTACEA.

483

the base of the limbs, under the thorax ; and these perform
the functions of branchiae. Finally, in the Crustacea isopoda,
respiration is accomplished by means of false abdominal
limbs, which are foliaceous and membranous.

§ 569. There exists a very small number of these animals
which live in air ; but they form an exception to what we
have already said relative to the differences of structure of
the respiratory apparatus in aquatic and terrestrial animals :
for in place of being furnished with lungs or tracheae, they
breathe by branchiae, like the first ; only these organs are dis-
posed in such a way as to maintain themselves in a moist
state required for the exercise of their functions. The ge-
carcini or land crabs (Fig. 516), met with in various regions

p ' p"' b pa pa. <)

Fig. 515.— Squilla (Shrimp).*

of the globe, but abounding especially in the Antilles, where
they are known by the name of tourlourous, present a
remarkable example of this anomaly. In place of living in
water as the ordinary Crustacea, they are terrestrial, and
although they have gills, some of them become asphyxiated
rapidly by submersion. Their respiration is, in fact, too
active for the small quantity of oxygen dissolved in water
sufficing for their wants ; whilst in the air, they of course find
this material in abundance ; and a disposition analogous to
that which we have already met with in fishes (Fig. 393), per-
mits them to remain out of the water without their branchiae
drying up so as to become unfit for the performance of their

* y, eyes ; a, antennae ; p', limbs of the first pair ; p", limbs of the three
following pairs ; p'", thoracic limbs of the three last pairs ; pa-, false abdo-
minal limbs ; b, branchiae ; g, caudal fin.

i i 2

484 ZOOLOGY.

functions. Sometimes there exists at the bottom of the respi-
ratory cavity a sort of trough, destined to act as a reservoir
for the water required to maintain their branchiae in a moist
state ; at other times, we find on the arch of this cavity a
spongy membrane, which seems to serve the same purpose.
Most of these land crabs live in moist woods, concealing them-
selves in holes which they dig in the soil, but the localities
they prefer vary according to the species; some live in
low marshy grounds near the sea; others prefer wooded
hills far from the seashore, and at certain epochs these last
quit their usual place of abode to reach the sea.^

The cloportes (Fig. 505) are also terrestrial Crustacea,
whose aerial respiration is accomplished by means of folia-
ceous laminse situated under the abdomen, and which, in other
animals formed in the same way, perform the functions of
branchiae.

Fig. 516.— Gecarcius, or Land Crab.

§ 570. The Crustacea are all oviparous, and the sexes
almost always distinct ; but some are hermaphrodite. The
female may in general be distinguished from the male by the
greater size of the abdomen, and after having laid her eggs,
she carries them during a certain time suspended under that
part of the body, or even enclosed in a sort of pouch formed
of appendages belonging to the limbs ; sometimes the young
are produced in this pouch, and remain there until they have
passed through their first moulting. The young in general
do not undergo true metamorphoses. Sometimes, however,

* Such are the circumstances which render difficult all minute application
of the laws regulating the structure and functions of the now existing living
world to the remains we find in past geological epochs. That which seems
aquatic may have been terrestrial, and vice versa. Not that anatomy is at
all doubtful when fully known, but the soft structure being destroyed, we
want a valuable element in the inquiry. — E. K.

CLASS OF CRUSTACEA. 485

they acquire by the progress of age a greater number of limbs,
and there are some which completely change their form
during the early periods of life ; the lernsese offer us an
example of this transformation (Fig. 155).

§ 571. The class Crustacea, amongst which we must
arrange the cirrhipeda, placed by many naturalists, but erro-
neously, amongst the mollusca, is divided into five principal
groups, namely, —

The podophthalmaria, which have the eyes carried on
moveable peduncles, the anterior portion of the body fur-
nished with a carapace, ambulatory limbs, the mouth armed
with jaws disposed for mastication, and the organs of respi-
ration formed of branchiae properly so called.

The edriophthalmia, whose eyes are not pedunculated, the
thorax exposed, the ambulatory limbs, the masticatory buccal
apparatus and the branchiae replaced by a portion of the
series of the limbs.

The branchiopoda, in which the limbs are all foliaceous,
and perform at the same time the functions of fins and
branchiae.

The entomostraca, in which the limbs are natatory but
not branchial, and in which the mouth is usually organized
for suction. Finally, the Xiphosuri, in whom the mouth has
no appendages which especially belong to it, but is sur-
rounded with limbs, the base of which performs the functions
of jaws.

[When I first made the discovery that the vendace, the her-
ring, and many fine species of the salmonidae, live almost exclu-
sively on various kinds of the entomostraca, the view was
violently contested by naturalists ; and although the facts sub-
mitted to them admitted of no sort of doubt, to this day I have
not overcome their prejudices. The history of my inquiry was
afterwards taken up by my former student and assistant, Mr.
Henry Goodsir ; and his remarks, as those of an honest and
careful observer, may be found agreeable to the reader, more
especially as this most amiable and talented young man perished
in his youth. He was one of the companions of Sir John Franklin
in his last expedition.

*' Hearing our fishermen often speak of 'something' which
abounded in great quantities in the Firth of Forth during the
summer months, which they called Maidre, and of which they
never could give me a clear description, I determined to examine
it for myself.

"It was stated to me that this maidre was generally found

486 ZOOLOGY.

in greatest quantity round the Island of May, only during the
summer months, and especially during the time of the herring-
fishing.

"I find, however, that maidre must abound during the spring
months also, as the stomachs of the herrings caught at present
are in most cases filled with it.

" In frequent excursions to the Isle of May, during last year,
I found that the maidre consisted of one immense continuous
body of minute animals.

" The animals composing this immense body were those
belonging to the cirrhipeds, crustaceans, and acalepha.

"Of these the crustaceans existed in the greatest numbers, or
rather masses, for it gives a faint idea to speak of numbers. The
Crustacea were amphipoda and entomostraca, the former of
which were very abundant, but the latter (entomostraca) formed
the greatest proportion of this innumerable body of animals.

"The acalepha also abounded, of which the different species
of beroce were seen in greatest numbers.

" I remarked that the masses of maidre abounded most at the
sheltered sides of the island. On looking into the water, it was
found to be quite obscured by the moving masses of entomo-
straca, which rendered it impossible to see anything, even a few
inches below the surface.

"But if by chance a clear spot is obtained, so as to allow the
observer to get a view of the bottom, immense shoals of coal-fish
are seen swimming lazily about, and devouring their minute
prey in great quantities. Occasionally small shoals of herrings
are seen pursuing them with greater agility. It is in the deep
caverns, however, in the sides of the island, where the maidre is
found in greatest abundance ; and accordingly, we find that all
those animals pursuing them are found there in greater abun-
dance also.

"The fishermen, during the earlier periods of the fishery, take
advantage of this, and, shooting their nets across the mouths of
the caves, alarm the herrings in them, either by throwing large
stones from their boats or from the tops of the rocks, and in this
way sometimes succeed in taking great shots.

" These, however, are not the only animals which prey on the
immense bodies of maidre,

"Great numbers jof cetacea often frequent the neighbourhood
of the island at this time ; droves of dolphins and porpoises,
swimming about with great activity ; arid occasionally an im-
mense rorqual may be seen raising his enormous back at intervals
from the water, and is to be observed coursing round and round
the island.

" I have examined great numbers of these cetaceous animals
(dolphins and porpoises) within the last few years, and never

CLASS OF CRUSTACEA. 487

have seen anything resembling the remains of herrings, or fish
of any other kind, in the stomach, although the former fish was
very abundant at the same time in the Firth. I make no doubt,
therefore, that the cetacea only accompany the herring in pursuit
of their common food, viz., entomostraca and acalepha.'

"I. have already stated that it was entomostracous animals
which formed the great mass of the maidre. Among these I
obtained a great number of nondescript species, one of which I
shall now describe.

" On one of my occasional visits to the Isle of May, I observed
that at a considerable distance from the island the sea had a
slightly red colour, that this became deeper and deeper as we
neared the island ; and also that the surface of the water pre-
sented a very curious appearance, as if a quantity of fine sand
were constantly falling on it. I thought at first that this last
circumstance proceeded from rain, but presently I found that
both phenomena were caused by a great number of small red
entomostraca, which I had never before observed in such abun-
dance. On further observation, I found that it belonged to the
genus Cetochilus of M. Rousel de Vauzeme, who has given a
detailed description of his species (C. Australis), the only one
hitherto known, in the first vol. of the Annales des Sciences
Naturelles. This author states that it is found in the Pacific
Ocean, and in the middle of the Atlantic Ocean, about 40° south
latitude. It forms, he says, very extensive banks, which impart
a red colour to the water, and which furnish a plentiful supply
of food to the whales frequenting those seas." — R. K.]

§ 572. The division of podophthalmaria comprises the
greater number of Crustacea, and is composed of all those
whose organization is the most complex and the most perfect.
It is subdivided into two orders, the decapoda and the
stomapoda.

§ 573. The order of the decapoda comprises the crabs,
lobsters, and all the other Crustacea in whom the branchiae
are internal, and in whom the limbs are five pairs in number.
The head and the thorax of these animals are confounded
into a mass covered by a large carapace or case (Fig. 517) ;
this dorsal buckler advances in general more or less in front,
descends on each side to the base of the limbs, and backwards
as far as the origin of the abdomen (Figs. 504, 507). It results
from this arrangement that we can no longer recognise
throughout all this part of the body any trace of an annular
division ; but beneath, most of the rings, although united
together, are still recognisable, and leave at their points of
junction the lines of suture, more or less distinct. The eyes

488 ZOOLOGY.

are always carried on the extremities of a pair of moveable
appendages which spring from the first segment of the head ;
sometimes the length of their peduncle is very considerable
(Fig. 510), and in general they may be folded or withdrawn
into the cavities performing the office of orbits, and which are
formed by the anterior margin of the carapace, shell, or case.
The organs of locomotion are also very well developed in these
Crustacea: several can run with extreme rapidity, others
swim still more swiftly. Their limbs, as we have already
said, are five pairs in number, fixed to the five last rings of
the thorax ; but in general those of the four last pairs alone
serve for locomotion, and those of the first pair terminating
in a forceps more or less perfect, become instruments of
prehension (Fig, 517). In the decapoda the best adapted
for swimming (such as the cray-fish, the lobster, and the
pabemons), the body is elongated, and the abdomen ter-
minated by a large transverse fin (Fig. 504) ; whilst in
those which are formed for running, the crabs, for example,
the abdomen is very short, has no terminal fin, and is curved
under the thorax.

Fig. 517.— Common edible Crab ; C. Pagurus.

§ 574. The stomapoda have also the eyes carried on move-
able peduncles, the thorax covered entirely or partly by a
carapace, and the limbs cylindrical ; but their branchiae are
not enclosed in the cavities of the thorax, but float nnder the
abdomen, or are altogether wanting. The squilla (Fig. 515),
of which we have already spoken, belongs to this order.

§ 575. In the division edriophthalmia, the head is distinct

CLASS OF CRUSTACEA.

489

from the thorax, and this last part of the body is composed
of a series of seven rings, each carrying a pair of limbs.
Thus, as we have already said, there is not any carapace, the
eyes are not pedunculated, there are no branchiae properly so
called, but the respiration is performed by means of various
appendages borrowed from the locomotory apparatus. Na-
turalists arrange under this group,

1. The amphipoda, which have the abdomen well developed,
and carry under the thorax a double series of respiratory
vesicles, formed by the internal branchiae of the limbs. The
prawns of rivulets and the talitri (Fig. 169) offer us these
characters.

2. The loemodipoda, which resemble the preceding in the
disposition of the organs of respiration, but which have only
a rudimentary abdomen.

Fig. 518.— Anilocra.

Fig. 519.— Limnadia.*

3. The isopoda, in whom the abdomen is, on the contrary,
well developed, and carries beneath a series of false branchial
limbs. The anilocra (Fig. 518), the sphaeroma, and the class
woodlouse, cloportus (oniscus) belong to this order.

§ 576. The branchiopoda, as we have already said, are
small crustacea, whose limbs no longer serve for walking, but
assume the form of foliaceous plates, constituting at one and
the same time organs of natation and respiration. Such are the
limnadiae, which have been already mentioned (Fig. 519), the

* One of the valves of the carapace has been amoved.

490 ZOOLOGY.

apis, the branchipes, the daphnise. It is to this group that
the trilobites seem to have belonged : marine animals, whose
fossil remains are found in the most ancient strata of the
globe, but of which there exists not at present any living
representative in the seas.

§ 577. The entomostraca are also formed only for
swimming, and in youth they all possess a certain number of
rigid double-oared limbs ; but in the adult state they are
mostly sedentary, and then the body becomes deformed in a
very singular manner ; in general they have but a single eye,
placed in the middle of the forehead, and their respiration
seems to take place over the whole surface of the body.

Fig. 520. — Cyclops ; one of the Entomostraca.

§ 578. tSome, called copepoda, are always very active, and
possess large antennae and a masticatory apparatus ; these are
the cyclops, or monocules (Fig. 520).*

§ 579. Others live as parasites on fishes, Crustacea, &c.,
and have the mouth elongated in the form of a proboscis or
beak, armed with style-formed appendages adapted to pierce
the integuments of the animals whose juices they suck. They
have been divided into the siphonostoma and the lernsea; the
first have always swimming limbs, ahd attach themselves by
means of limb-jaws Having the form of hooks ; the second, on
reaching the adult age, present no longer any traces of loco-
motory organ's, and have often been confounded with the
intestinal worms.f

§ 580. It is also in this division of the entomostraca that

* The Entomostraca play an important part in the great economy of
nature. They form the especial food of many valuable fishes of the family
salmonidae, clupeidae, and coregoni; and it is evident, from the remains in
the limestone strata, that they abounded, and were perhaps of a larger size
generally, in the seas and fresh waters of the ancient world. — E. K.

t A species of lernaea attacks the gills of the salmon during its residence in
fresh waters, but seems to perish when the fish return to the sea.— B. K.

CLASS OF CRUSTACEA. 491

we must arrange the cirrhipeda, which at first sight seem to
have many analogies with the mollusca, more so indeed than
with animals of the class we now describe ; but in fact they
are only Crustacea with the hody deformed after they have
ceased to lead a wandering life. When young, these small
beings, which are all marine, swim freely, and resemble
extremely certain ordinary entomostraca, such as the young
cyclops (Fig. 158) ; but soon afterwards they become fixed,
so long as their life endures, to some submarine body, and

Fig. 521.— Anatifae; Barnacles.

completely change their form. It is by the back that they
thus adhere, and their body, more or less pyriform and
curved on itself, is enclosed, in whole or in the greater part,
in a kind of shell, composed of several pieces (Fig. 521).
They have no eyes, and their mouth is furnished with man-
dibles and jaws having the strongest resemblance with those
of certain Crustacea ; the abdominal aspect of their body is
occupied by two rows of fleshy lobes, having each long horny

492 ZOOLOGY.

appendages, furnished with cilia, and composed of a great
number of joints. These kinds of arms or cirrhi, numbering
twelve pairs, are curved on themselves, and the animal con-
stantly protrudes and withdraws them by the opening of its
sheath or case. At the extremity of this series of organs is
found a kind of tail, having the form of a long fleshy tentacle,
at the base of which is the anus. Their nervous system is
composed of a double chain of ganglions, disposed exactly as
in the other articulated animals. They have a heart, lodged
in the dorsal part of their body, and they breathe by branchiaa
whose form varies.

The cirrhipeda are divided into two families — the anatifse
and the balani.

The Anatifas (Fig. 521) — called also lepas anatifera and
Barnacle — are enclosed in a kind of compressed mantle, open
on one side, and suspended by a long fleshy peduncle ; some-
times this mantle is almost entirely cartilaginous : at other
times it is covered by five testaceous plates, of which the two
principal ones bear some resemblance to those of a mussel.
The common anatifa dwells in our seas, and is frequently
found attached to rocks, to the keels of ships, and to pieces of
floating timber. It has been the subject
of most absurd fables ; some coarse resem-
blance of its shell to a bird gave origin to
the silly tale that from these animals came
the goose called barnacle.

The Balani or sea acorns (Fig. 522) abound
on the rocks of our seas, and are contained

Fig. 522. Balanus, wh.oll7 in a, ki?d of shell generally conical,
or Acorn Shell, and very snort, nxecl by its base, and com-
posed of several lappets articulated with
each other : the opening of this tube is occupied by two or four
moveable valves, between which is found a fissure destined to
give passage to the cirrhi.

§ 581. Finally, the division of Crustacea called xipho-
sura is composed only of a single genus, that of the limulus,
whose structure is most anomalous. These are large crus-
tacea, whose bodies are divided into two parts; the first,
covered by a semicircular buckler, has eyes, antennae, and six
pairs of feet surrounding the mouth, which serve at the same
time for walking and for mastication (Fig. 142) ; the second
portion of the body, covered by another buckler, almost
triangular, carries beneath, five pairs of swimming limbs,

CLASS OF CRUSTACEA. 493

whose posterior aspect is covered with branchiae ; and it ter-
minates with a long styliform. tail. These singular animals
inhabit the Indian Ocean and the coasts of America ; they
are known by tHe common name of Molucca crabs.

Fig. 523.— Lhnulus, or Molucca Crab. King Crab.

[" As there is scarcely a subject more interesting in natural
history than that part of it which treats of the various meta-
morphoses which all animals undergo in their progressive growth
from the embryonic to the adult condition, I have ventured to
subjoin the observations made on this subject by a former most
esteemed student of mine, and a careful observer.* They refer,
no doubt, especially to the class cirrhipeds, but mutatis mutandis
apply to all. In my late inquiries into the dentition of the
salmon, other singular facts have come out, plainly disproving
the opinion of M. Valenciennes, that * Naturalists have only to
do with the adult forms.' For all these adult forms or species
are included in the history of the young, as I have proved with
regard to the salmonidae ; whilst all transcendentalists since the
time of Goethe and Oken have known that the larva conditions

* Mr. Henry Goodsir, in the Edinburgh Philosophical Journal.

494 ZOOLOGY.

of many living species typify, or are types of, adult forms or
species now extinct ; that is, of the adult forms of the fossil
world. Thus it is that the history of the organo-genesis, of the
metamorphoses of the young, elucidates the history of the or-
ganic world, past and present, connecting them together into one
great whole, the accomplishment of one vast design. The laws
of deformation, even in man, are as yet but little understood.
One thing is certain ; namely, that for the future zoology cannot
be based on any exclusive method or mode of research, but must
seek for its illustrations and views in the entire range of descrip-
tive and philosophical anatomy, to which must be superadded
the careful observation of external characters. Here are Mr.
Goodsir's remarks : —

' There is no set of animals which has caused greater annoyance
to systematists than the cirrhipeda.

'They were first arranged by Linnaeus along with the testa-
ceous mollusca. Cuvier at first followed this arrangement, but
latterly placed them in a distinct class by themselves, between
the mollusca and articulata. Lamarck, Latreille, M'Leay, and
other authors, followed this latter arrangement ; the two last
authors acknowledging, at the same time, their closer connexion
with the articulata.

'The decision of this important question, however, was left to
our countryman, Mr. J. V. Thompson. This gentleman having
obtained some minute mussel- like animals, at first considered
them to be nondescripts belonging to the crustaceans, but on a
further examination, and by keeping a few of them alive in glass
vessels of sea-water, he was soon enabled to make out their
nature and relations satisfactorily. To use Mr. Thompson's own
words — ' They were taken on the 1st of May, and on the night
of the eighth the author had the satisfaction to find that two of
them had thrown off their exuvia, and wonderful to say, were
firmly adhering to the bottom of the vessel, a^d changed into
young barnacles.' The above-mentioned statements set at rest,
in a great measure, the previous discussions as to the position of
the cirrhipeds in the animal kingdom.

' In the beginning of March of the present year (1843), while
Professor Reid* of St. Andrews and myself were watching the
movements of some very large balani (Balanus Tintinnabidum),
we observed a few of them ejecting with considerable force a
great quantity of small granules every time the cirrhi were re-
tracted. No great attention was paid to this at the time. Next
day, however, we were astonished to find the basin in which the
balani were confined swarming with an innumerable number of

* Dr. Keid was my student and assistant for several years ; he was a dili-
gent anatomist. — E. K.

CLASS OF CKUSTACEA. 495

extremely minute but very active animals, when it immediately
struck us that these must have been the young which the balani
were throwing off the day before. On placing one of these animals
under the microscope, we expected to find one of those mussel-
like animals described by Thompson ; but instead of that, it 1 ad
an almost exact resemblance to the young of the genus cyclops.
To make sure that there had been no mistake, one of the adult
balani was opened, when the large cavity of the mantle was found
to be filled with the granules which we had formerly seen ejected.
A few were placed in a watch-glassful of sea-water under the
microscope. They were quite motionless, of an ovoid shape,
sharper at one extremity than the other. The eye, or rather
what was considered to be the eye, was observed a little before
the middle line, and near to the superior edge. In the course of
a short time, a few began to make some efforts to escape. After
they had done so, they were found to resemble, in their external
appearance, the young cyclop ides alluded to above. At first, the
efforts to escape were feeble, but latterly they became more
violent ; and by means of the tail, which was suddenly and for-
cibly jerked upwards and downwards, the membranes which
contained them were burst on the abdominal surface, upon which
the young animal escaped. It was some time, however, before
the extremit;es were completely freed. In the course of ten or
fifteen minutes after they had been taken from the body of the
mother, these young animals were all free, and the empty sacs
were lying amongst them. They have a striking "resemblance, in
their external appearance, to the larvae of the cyclops ; and if we
had not had the certain evidence of having seen them taken from
the body of the mother, we would have pronounced them young
cyclopides.

* After many fruitless endeavours, we found it impossible to
preserve them alive for any length of time, and were, therefore,
disappointed in our expectations of seeing them undergo their
metamorphoses. We were, therefore, uncertain whether they
underwent a first and second metamorphosis, and changed first
into the mussel- like form described by Thompson, and then into
the parent form, or were simply metamorphosed into the parent
form. Seeing that this is a distinct species from that described
by Mr. Thompson, it is impossible to decide this question until
farther observations have been made. Having been fortunate
enough, however, in making a series of observations of the same
nature on the young of the balanus balanoides, which are recorded
above, it will now be seen that this question is already decided,
viz., that the balani must undergo two changes of form, or per-
haps more, before arriving at a state of maturitv.

' We will now proceed to give a short description of the larva
of this species.

496 ZOOLOGY.

' When viewed from above, the body of the animal is found to
be pyriform, with the anterior edge rounded, and the posterior
extremity ending by means of a point. The whole body consists
of three segments : the first forms the greater part of the body ;
the two last are minute. Two long unarticulated extremities
project from the anterior edge on either side of the mesial line,
arising, apparently, from the abdominal surface of the body. Two
short antennae arise also from this edge, immediately on each side
of the above- described extremities.

' The eye is situated a little behind the anterior edge, and in
the mesial line of the body.

' Two very strong thick legs arise from each side of this first
segment of the body. These are bipartite, each division arising
from a pedicle common to both, which consists of three segments.
The divisions themselves are apparently unarticulated, but are
armed with a number of very strong spines.

' The second segment of the body is minute. The third and
last is also minute and pointed, and is armed with three strong
spines, which are bent to one side (the left side), that nearest
the right side being the shortest.

' All of these larvae swim after the manner of the monoculi, by
short and sudden jerks. They propel themselves by means of
the two pairs of spined extremities. The tail is also in constant
motion.' — H. G., in E. P. Journal.

"By the minute and prolonged study of the metamorphoses of
animals, we thus prove that these so-called imperfect forms, or
forms in transitu, are the permanent forms of adult extinct and
recent animal beings. Thus we upset the theory of the transmu-
tation of species, and creation of new forms ; for these forms are
embraced in the embryonic, and require but time and circum-
stances for their full development : nevertheless, I willingly
concede to my esteemed friend, M. Valenciennes, that the natu-
ralist is only interested in adult forms, these being the highest
specializations to which animals attain: it holds even in man
himself."*— R. K.]

* See my Manual of Artistic Anatomy. Renshaw, London.

OF THE ANNELIDES. 497

THE SECOND SUB-DIVISION.
OF THE ANNELIDES, OR ANNULATED ANIMALS.

THE YEBMES, OR WORMS.

§ 582. In these animals the annulated division of the
body becomes less and less marked ; every structure becomes
as it were degraded in proportion as we leave those most re-
sembling the articulated to those approaching the zoophytes ;
the limbs disappear, and the nervous system becomes less and
less distinct, or loses its importance, and the structures sim-
plify more and more. Their most remarkable feature is the
elongation of their bodies, and they form five distinct classes ;
namely, the annelides, rotatoria, turbellaria, helminthides or
intestinal worms,* and cestoids.

OF THE ANNELIDES.

§ 583. The class is composed of worms having a multi-
gangular nervous system, and a vascular apparatus for the
circulation of the blood.

Fig. 524.— Nereis ; Mudworm.*

Their bodies are always elongated, soft, and divided by cir-
cular folds into a great number of rings ; sometimes the head
is distinct, sometimes it is wanting ; and generally along the

* Entozoa.

t Called mudworm by the fishermen of Dover, who use them as bait for
the white mullet, numbers of which are taken by angling at the mouth of the
harbour.— E. K.

K K

498

sides of the body they have a long series of hairs in bundles,
supported on fleshy tubercles, taking the place of feet (Fig.
524). Frequently we find two of these organs placed one
above the other, on either side the different rings of the
body (Fig. 413) ; at other times these
bristle-carrying tubercles are reunited,
and there is found at the base of each
a long, soft cylindrical appendix called
cirrhus (c, Fig. 525) ; sometimes the
place of the feet is marked by merely
a few stiff hairs, whilst in others all
traces of limbs have disappeared.
These hairs or bristles serve as instru-
ments of defence and of locomotion;
they are in general sharp, and calcu-
lated to attach the animals to any soft
body with which they come in contact. In the annelides,
which have no bristles, there exist at the extremities of the
body, suckers which answer the purpose.

§ 584. Their nervous system consists of a chain, single or
double, of very small ganglions, extending from one extremity
of the body to the other. Most have a few dark spots, which

Fig. 525.*

Fig. 526.— Head and Proboscis
of a Glycera.f

Fig. 527.— Head, &c.,
of a Nereis.

seem to be the eyes, and the head is usually provided with a
number of filaments analogous to the cirrhi of the feet, and
called antenna? and tentacular cirrhi (Fig. 527), which seem to
be organs of touch. The mouth is on the inferior aspect of

* Feet of an Annelid of the genus Eunice : — t, setigerous tubercle ; e,
dorsal cirrhus ; ci, inferior or ventral cirrhus ; b, branchia.

t e, anterior part of the body j t, the head ; tr, proboscis ; b, buccal
opening ; m, jaws.

OF THE ANNELIDES. 499

the bead, or the anterior extremity of the body, when there
is no distinct head ; it is often armed with a protractile pro-
boscis (Fig. 526), and with jaws having the form of horny
hooks. The intestine is straight, simple, or furnished with
caeca, placed on either side ; the anus is at the extremity of
the body.

The blood is almost always red ; sometimes it is green, and
at others scarcely coloured ; it circulates in a complex system
of vessels, varying in different species ; of these vessels some
are contractile, and perform the function of a heart; others
those of arteries and veins.

Fig. 628.— A Group of Serpulse.

The respiration of these animals is generally ae'rian, but
sometimes aquatic, and in this case it is performed by means
of external branchise, whose form and arrangement vary
much ; sometimes they resemble little trees or leaves, and are
fixed above the feet on each side of the back, as in the areni-
cola (Fig. 56) ; at other times they resemble bunches of
feathers, and unite in a corona around the extremity of the
body, an arrangement of which we have an example in the
serpula (Fig. 528).

§ 585. Most of the annelides live in the sea, and several
K K. 2

500

ZOOLOGY.

construct as dwellings a long tube, formed either of calcareous
matters secreted by the skin (Fig. 528), or consisting of
sand and fragments of shells, agglutinated by means of a
gelatinous substance ; several, as the arenicola, plunge deeply
in the sand (Fig. 56); others conceal themselves under stones ;
finally, there are annelides, as the leech, which live in fresh
waters : so also does the nais, which more resembles the earth-
worm ; and these last, called by zoologists lumbrici, are land
animaLs.

CLASS OF THE KOTIFERA.

§ 586. These beings, which have been often confounded with
the infusoria, are nevertheless quite distinct. Their structure
is very complex, and we owe the discovery of this fact to the
microscope, and to the profound researches of M. Ehrenberg,
of Berlin. Before his time they were thought to be animals

Fig. 529.— The Hydatina.*

* Anatomy of the Hydatina, a microscopic animalcule next the Botifera :
a, vibratile cilia ; b, fleshy mass surrounding the mouth and moving the
j aws ; c, the stomach ; d, the cloaca ; e, the anus ; f, salivary glands ; g,
ovaria ; h, the muscles.

CLASS OF THE EOTIFERA.

501

composed of animated jelly, nourished by imbibition ; now it
is no longer the simplicity of their structure which surprises
us, but the complication of their organization, wholly micro-
scopic.

These animalcules are met with in stagnant waters. Their
body is semi-transparent, and presents traces sufficiently dis-
tinct of annular divisions. The mouth occupies the anterior
extremity, and on each side, or even all around the orifice,
may generally be seen vibratile cilia, the rotatory movements
of which are extremely remarkable. Almost always the

Fig. 530.— Fluke Worm ; Fasciola Hepatica.

pharynx (arriere boucke) is furnished with powerful muscles,
and armed with lateral jaws. The digestive canal is straight ;
it extends from one extremity of the body to another, and has
generally towards the middle an enlargement representing
the stomach of these small beings ; often may be seen, on
either side of this tube, bodies apparently glandular, and at
its posterior extremity a sort of cloaca, in which terminate
the oviducts. A great number of muscles have also been dis-

502 ZOOLOGY.

covered in these animalcules, and even a ganglionary nervous
system.

§ 587. The rotifera — wheel bearing animals — (Fig. 177),
one species of which has become celebrated by the experiments
of Spallanzani on the suspension of life which follows its drying
up, may be taken as a type of the class. Their body is elon-
gated, and is terminated anteriorly by two small coronse of
cilia, which at the will of the animal are withdrawn into the
interior or expanded externally, and which by their vibrations
produce the image of two small wheels turning rapidly on
their axes. They terminate in a bifurcated and articulated
tail, by which they attach themselves to bodies on which they
wish to rest ; finally, two small red points seem to represent
the eyes. These animalcules swim with the greatest vivacity,
and lay oval eggs.

§ 588. Other animalcules, called branchions, resemble the
rotifera in the general mode of their organization, but merit
notice by reason of a sort of carapace, or shell, with which
their body is covered. In several of these small beings the
shell or covering is even bivalve, and recals very much that
of certain Crustacea, such as the cypris and daphnia.

CLASS OF TUEBELLAEIA.

§ 589. This class ought to comprise a certain number of
vermes, whose body, more or less compressed, presents
scarcely any traces of annulation, and is covered with ex-
tremely fine vibratile cilia. In general they have no anus,
and their digestive apparatus is ramified, and terminates in a
cul-de-sac ; their nervous system is composed of two lateral
cords, terminating anteriorly in a pair of cerebroid gan-
glions, and they have distinctly-formed bloodvessels. Some,
as the nemertes and the planaria, live in water. Others, as
the fluke (Fasciola Hepatica, Fig. 530), are parasites, and
live in the interior of other animals.

CLASS OF HELMINTHES, OE NEMATOlDS.

§ 590. This division is composed of a part of those animals
sometimes called intestinal worms, by reason of their living
generally as parasites in the intestinal canal of man and of

CLASS OF CESTOIDS OE T^NOIDS.

503

most other vertebrata.* The nematoids (helminthes) have the
body cylindrical, and attenuated
at the two extremities ; ex-
teriorly they greatly resemble
earth-worms, and also, as in the
annelides, their intestinal canal
is simple, and extended from
one extremity of the body to the
other ; but their nervous system
is rudimentary, and their blood
is colourless.

The principal genera of this
class are, the ascarides (Fig.
178), the strongyli, and the
filaria.

CLASS OF CESTOIDS OK
T^NOIDS.

§ 591. The cestoids are also
intestinal worms, but they
differ from the nematoids (hel-
minthes) greatly in their form
and mode of organization, and
more resemble the turbellaria.
They have the body flattened,
much elongated, and divided in-
to a great number of segments,
which gives them the appear-
ance of a long ribbon folded
transversely. Their nervous
system is rudimentary, and
their intestinal canal appears to
be replaced by two longitudinal
vessels occupying the sides of
the body. They are hermaphro-
dite, and each ring (segment)
of their body possesses a com-
plete reproductory apparatus,
belongs to this division (Fig. 531).

* It would seem from the researches of Van Beneden and others, that
these parasitical animals are introduced into the bodies of others from with-
out, in the condition of ova in fact, and that their future development
depends on their reaching the habitat suited to them. — R. K.

Fig. 531.— Tape Worm, Taenia.
The tcenia, or solitary worm,

504 ZOOLOGY.

DIVISION OF THE MOLLUSCA, OR MALACOZOARIA.

§ 592. The division of the mollusca is composed, as we
have already said, of a considerable number of animals which
have neither a cerebro- spinal system nor an internal skeleton,
and which resemble in these respects the articulated animals,
but not having, as these have, the body divided into rings,
nor the ganglions (nervous) reunited into a long median chain
placed on the ventral aspect of the body. They are distin-
guished also from zoophytes by the disposition of the organs
of relation being arranged in pairs, and in general they have
the mouth and anus more or less close to each other. More*
over, they differ much from each other, and are divided into
two principal series, — namely, the mollusca properly so called,
and the molluscoides or tunicata.

SUB- DIVISION OF THE MOLLUSCA
PROPERLY SO CALLED.

§ 593. Iii this group the nervous system is -always com-
posed of several ganglions, reunited by medullary cords, so as
to form a sort of double collar, more or less closely around
the gullet, but not prolonged posteriorly like a sub-intestinal
chain, as in the annulated animals.

The general form of these mollusca is extremely variable.
Their body is always soft, and in a small number only (the
sepia, for example) there exist in the interior some solid
non-articulated pieces, serving rat-hereto protect the viscera
than to furnish to the locomotory apparatus levers and points
of support. The muscles are fixed directly into the integu-
ments, and seem to act only on the point into which they are
inserted ; and thus the movements of the animal are slow
and ill directed. In a small number of these beings (the
sepia, for example) there are flexible and elongated appen-
dages (Fig. 185), intended for locomotion, but in most
instances the animal cannot displace itself but by successive
contractions of various points of the lower surface of its
body; and even when there exist limbs, these organs are
reunited in a group at one extremity of the body, and never

SUB-DIVISION OF THE MOLLUSCA. 505

disposed in a symmetrical series, as in the vertebrate and
articulate animals.

The skin of the mollusca, always soft and viscous, often
forms folds which envelope more or less completely the body ;
and this disposition has induced zoologists to give the name
of mantle to that portion of the integument generally fur-
nishing these expansions. This mantle is often entirely free,
forming two large veils or coverings concealing all the rest
of the animal, or these two laminse unite so as to form a
tube ; but at other times it consists only of a kind of dorsal
disc, of which the edges alone are free or surround the body
more exactly under the form of a sac.

§ 594. In general the soft skin is protected by a kind of
stony or hard cuirass, called shell. It is a tissue which has
some analogy with that of the epidermis, which constitutes
this envelope. The follicles lodged generally in the edges of
the mantle, deposit on its surface a half-horny matter, mixed
with carbonate of lime in greater or less proportions, and is
moulded over the subjacent parts, and next solidifies. The
lamina thus formed thickens and grows by the successive
deposit of new matter. Its surface is not stony, but resembles
a kind of epidermis, and is known by the name of drap marin,
or sea- cloth ; sometimes it preserves a horny consistence
throughout its whole thickness, but in general the proportion
of carbonate of lime which it encloses gives to it a stony
hardness. Its inner surface is frequently more dense than
the rest, and presents a peculiar structure rendering it glassy,
lustrous, and pearly. Sometimes the shell remains always
enclosed in the thickness of the skin of the animal; but
generally it is external, and even passes beyond the edges of
the mantle, so as to furnish to the animal perfect shelter. The
name of naked mollusca has been given to those which are
without shells, or which have only an interior one, and the
name of conchifera to those in which the shell is visible
externally.

The manner in which this shell grows may be readily un-
derstood. If we examine the shell of an oyster, for example,
it will be found to be composed of a number of superimposed
laminae, which can be separated by means of heat. These
plates have been formed successively by the mantle of the
animal, which they cover, and consequently the most external
is the oldest, or first formed, and the smallest; each new
plate deposited passes beyond the plate situated above it,

506 ZOOLOGY.

so that the shell as it grows in thickness also enlarges rapidly.
In general, the distinction of laminae whilst forming is
less marked, and the new matters are often deposited only on
the edge of the shell, and in such a way that their molecules
correspond exactly to the molecules of the part already con-
solidated ; this gives to the whole a fibrous structure. Colours
the most varied and most agreeably disposed ornament these
shells, and often vary with age. Very generally they are
altogether superficial, and seem to depend on a sort of dyeing
process produced by the skin of the animal, which is painted
in a manner corresponding to its envelope. The colouring
matter appears to be deposited on the shell at the moment of
its formation ; it is also more lively as the shell is younger ;
it is produced by the edge of the mantle. In fact, if a shell
be broken, and the animal happens to repair this accident, the
part newly formed is always white where it has not been in
contact with the edge of the mantle ; and if it corresponds
with this edge, it assumes the colour which this presents at
the point of contact. Thus when the edge is spotted, corre-
sponding spots are found upon the edge of the shell ; and as
this elongates, these spots become confounded with those
already formed, and produce lines perpendicular to the striae
of increase, or do not unite with them, and remain insulated,
according as the mantle remains immovable, preserving with
the margin of the shell the same relations.; or, on the other
hand, that by the movements of the animal it often changes
its position. Sometimes the secretion of colouring matter also
varies with age, and accidental circumstances may equally
modify it. Light, for example, exercises over the phenome-
non a very remarkable influence, and not only the shells which
are the most exposed to the action of this physical agent are
generally the most brilliantly coloured,^but when the mollusc
lives fixed on a rock, or partly concealed under a sponge or
some other opaque body, the portion of the shell thus placed
in obscurity is always paler and duller than that exposed to
the contact of the sun's rays.

§ 595. The digestive apparatus of these animals is strongly
developed. There exists always a large liver, and often we
find salivary glands and organs of mastication ; but the intes-
tines are never supported by a mesentery. Their blood is
colourless, or slightly bluish, and circulates in a very complex
apparatus, composed partly of arteries and of veins, and partly
only of lacunaB. A heart, formed of a ventricle, and of one or

CLASS OF THE CEPHALOPODA. 507

of two auricles, is found in the course of the arterial blood,
transmitting this liquid into all parts of the body, from whence
it returns to the organ of respiration by canals more or less
incomplete. We sometimes also meet with, at the base of the
vessels entering the organ of respiration, contractile venous
reservoirs called pulmonary hearts.

With regard to the arrangement of the organs of respira-
tion, it varies too much to allow of us describing it in this
place. We shall therefore only say that they have sometimes
the form of lungs, at others that of branchiae or gills.

§ 596. In like manner we cannot say anything generally
of the structure of the organs of sense, which, however, are
always less complete than in vertebrate animals. Certain
mollusca seem to be gifted only with the senses of touch and
taste ; but a great number have eyes, whose structure varies,
and in many of them there even exists an apparatus for- hear-
ing ; but none have yet been found possessing a special organ
for smell.

The mollusca spring from eggs, and never multiply by
granulations, as happens in most of the molluscoides, but
sometimes these eggs are hatched externally, sometimes in
the interior of the body of their parent, which may then be
said to be ovoviviparous.

§ 597. The sub-division of the molluscs properly so called,
is composed of four principal groups or classes, called the
cephalopoda, gastropoda, pteropoda, and acephala. We shall
now make known their more prominent characters.

CLASS OF THE CEPHALOPODA.

§ 598. This class is composed of mollusca of an extremely
odd form, for their head is placed between the trunk and the
feet, or tentacula, serving for locomotion ; and when they
walk, it is with the body upwards and the head downwards
that they draw themselves along the soil (Fig. 185) ; in fact,
it is on the head, around the mouth, that their feet are in-
serted; and hence their name of cephalopoda. The trunk of
these animals is covered by the mantle, which has the form of
a sac, sometimes almost spherical, at others elongated, open
in front onl}r, and enclosing all the viscera (Fig. 533, o). The
head projects through this opening; it is round, and is gene-
rally furnished with two large eyes (Fig. 10), of a structure
very analogous to that of the eyes of vertebrate animals. The

508

ZOOLOGY.

mouth occupies the middle, and is armed with two jaws.
Finally, around this opening is a corona of flexible fleshy
appendages (Fig. 532), named, indifferently, arms or feet, and

Fig. 532. — Common Calmar (the Loligo Sagittarius) ;
a Cuttle Fish.

which merit equally both names, for they are at once the
instruments of prehension and of locomotion.

Fig. 533.— Gills of the Poulpe (Octopus) ;
Sepia, or Cuttle Fish.*

§ 599. The cephalopoda are essentially aquatic animals,
and they in consequence breathe by gills. These organs are

* The body of an Octopus, as seen on its inferior surface (the mantle is
laid open in the median line and on one side, and is turned outwards to show
the interior of the respiratory cavity) : — a, base of the head ; i, the tube by
which the water leaves the respiratory cavity ; o, one of the two lateral
openings by which the water penetrates into this cavity ; b, one of the bran-
chiae, or gills.

CLASS OF THE CEPHALOPODA.

509

found concealed in the mantle, under a particular cavity (Fig.
533), whose walls dilate and contract alternately, and whose
interior communicates with the exterior by two openings,
The one (o) in the form of a fissure serving for the entrance
of the water; the other, prolonged into a tube or funnel (t},
serving for the escape of the water and of the residue of the

a vc as b

vv av a cs vv

Fig. 534— Organs of Respiration and Circulation in the Cuttle Fish.*

food. Each gill (b) has the shape of an elongated pyramid,
and is composed of a great number of membranous lamellae,
placed transversely, and fixed on either side of the median

* c, the aortic heart, the superior extremity of which is continuous with
the superior aorta (as), distributing the blood to the head, &c. ; b, the
branches of this vessel ; a, the inferior aorta, presenting a bulb at its origin,
and soon dividing into two branches (vv) ; vc, vena cava, whose walls are
covered by the spongy bodies (e,«?) ; vv, veins of the viscera proceeding to
open into the two branches of the vena cava ; cp, venous sinuses or branchial
hearts; s, enlargement of the base of the branchial arteries; br, gills, ab,
branchial artery ; vb, branchial vein ; bu, bulb of the branchial veins situated
near the termination of the vessels in the heart, and constituting the
auricles.

/

510 ZOOLOGY.

stalk. The number of gills varies, and this difference is
characteristic of the two great natural divisions of which the
class is composed. In the octopus, the sepia, and the loligo,
there exists only a single pair ; but in the nautili there are
two pairs.

§ 600. The heart is situated between the gills, in the
median line of the body, and is formed of a single ventricle
(Fig. 534, c). The blood reaches it from the branchiae by the
branchial veins (vb), whose openings are provided with val-
vules, and tlius penetrates into the arteries which spring from
the organ, and are distributed to the body. This liquid
passes afterwards into a venous system composed partly of
vessels properly so called, and partly into cavities without
proper walls, hollowed out between the organs ; thus the space
comprised around the anterior portion of the digestive appa-
ratus performs the office of a venous sinus, and the principal
nervous ganglions, as well as various glands, are bathed in
the blood.

Finally, the nourishing fluid which thus returns from the
different parts of the body, traversing the visceral cavity, or
passing in veins properly so called, reaches at last a large
median trunk, whose branches proceed to the organs of respi-
ration, but generally penetrate first into a contractile reser-
voir situated at the base of each of these organs. These
reservoirs push the blood into the branchial vessels, and con-
sequently there are in these animals two pulmonary hearts as
well as an arterial ; but this arrangement, which exists in all
the cephalopoda with two gills, is wanting in the tetra-bran-
chial cephalopoda.

§ 601. The digestive apparatus is very complex. The
mouth is surrounded with a circular lip and with two man-
dibles, placed vertically one over the*other. They resemble
strongly the bill of the paroquet, and are moved by powerful
muscles. There are salivary glands, highly developed, several
stomachs, and a large liver. The intestine terminates in the
branchial cavity at the base of the funnel, by which the water
is expired, and communicates with a very singular secreting
organ, which in the cephalopods with two gills produces an
abundance of a black liquid, to which the name of ink has
been given. The excretory canal of this gland opens near
the anus ; and when the animal is in danger, it ejects by
the funnel a sufficiency of the dark fluid to colour the sur-
rounding water, and thus escapes from the sight of its

CLASS OF THE CEPHALOPODA.

511

enemies. It is the ink of one of those cephalopods, the
sepia, which is employed in painting under the name of sepia ;
and several authors think that China ink is an analogous

Fig. 535.— The Argonaut (Argonauta), in its shell. The Paper Nautilus.

512

ZOOLOGY,

substance.* The tetrabranchiate cephalopoda have no such
organ.

§ 602. We have said above that the mollusca have no
solid articulated framework comparable to the skeleton of the
vertebrata. Nevertheless, in the cephalopoda we still find
vestiges of something analogous ; for there is in the head a
cartilage which not only protects the brain, but also spreads

Fig. 536.— Nautilus ; the Pearly Nautilus.f

out in different directions, furnishing points of insertion to
the different muscles of the animal. It is also to be ob-
served that the abdomen of these animals is in general sup-
ported by a sort of internal shell, which in the loligo is horny,
but in the sepia is of a calcareous nature, and is called the
bone of the sepia.

* It would seem, however, that the colouring matter employed in the
fabrication of China ink is nothing but carbon, minutely divided.

t In this figure the shell is represented open :— tt the tentacula ; <?, the
funnel j p, the foot ; m, a portion of the mantle ; o, the eye ; », the syphon.

CLASS OF THE CEPHALOPODA.

513

§ 603. The disposition of the organs of locomotion and
prehension, fixed around the mouth, varies in these mollusca.

Fig. 537,— Nervous System of the Cuttle Fish (Sepia).*

* a, the nervous collar surrounding the gullet, the course of which is indi-
cated by a bristle (s] ; c, the nervous mass situated before the gullet, and
generally called brain : its superior surface is surmounted with a very large
cordiform tubercle, and there proceed from its anterior part nerves, which
soon terminate in a circular ganglion, which in its turn gives origin to
L L

514 ZOOLOGY.

In the dibranchiate cephalopodes there is a corona of large
fleshy tentacula, whose internal surface is provided with
suckers, by means of which they attach themselves with
much force to the bodies they lay hold of (Fig. 185). In the
poulpe (octopus) there are eight of these appendages, and in
the sepia ten ; sometimes two of these enlarge like oars or
membranous veils, as in the argonaut (Pig. 535), or elongate
so as to become filiform, as in the calmar (Fig. 532), and
especially in the calmaret (Fig. 10). In the tetrabranchiate
cephalopodes these appendages are all slender, without suckers,
and extremely numerous (Fig. 536).

§ 604. Most of the mollusca of this class are remarkable
for the development and perfection of their eyes, which
greatly resemble those of vertebrata. Several have also an
auditory apparatus, but this organ is reduced to a small
membranous sac, receiving a nerve.

Finally, the nervous system of these animals is more com-
plex than in the other mollusca, and the various ganglions
grouped around the gullet have a tendency to coalesce into a
single mass. The medullary collar so formed is composed of
a pair of cephalic ganglions, whence arise the optic nerves,
&c. ; of a pair of ganglions, situated more forward, but under
the gullet, and furnishing the nerves of the tentacula (Fig.
537) ; finally, of a pair of thoracic ganglions, giving origin
to the nerves of the mantle, and to two cords which, proceed-
ing backwards, form on each side of the abdomen a ganglion,
from whence arise the branches destined for the heart, gills,
&c.

§ 605. All the cephalopodes are marine ; they are very
voracious, and live chiefly on Crustacea and fishes, which
they seize with their supple and vigorous arms, and whose
flesh they easily devour by means of -their sharp mandibles.
Some of these animals are lodged in shells turned on them-
selves : such are the argonaut and the nautilus ; but some
naturalists think that the first does not itself form the cal-

another pair of nerves which descend under the mouth so as to embrace
the gullet anew, and to form there a small anterior ganglion, whence arise
the labial nerves ; b, tentacular ganglions, whence arise the nerves of the
arms ; o, optic nerves, arising from the lateral pnrts of the brain, and soon
swelling into a large ganglion ; t, small venous tubercles, situated on the
origin of the optic nerves; g, cesophageal or ventral ganglion; v, great
visceral nerve, one of the branches of which has on it an elongated ganglion
(r), and penetrates into the gills ; m, nerves which arise also i'rom the post-
cesophageal ganglions, and which have on their passage a large star-shaped
ganglion (e), whose branches proceed to the mantle.

CLASS OF THE GASTEBOPODA.

515

careous covering, but lives as a parasite in the shell of another
mollusc.

This class comprises the octopus (Fig. 185), the argonaut
(Fig. 535), the sepia, the calmar (Fig. 532), the calmaret

Fig. 538. — The Ammonite j an extinct mollusk.

(Fig. 10), the nautilus (Fig. 536), &c. With these are arranged
the ammonite shells, which have some analogy with those of
the nautilus, but are found only in a fossil state.

CLASS OF THE GASTEROPODA.

§ 606. The gasteropoda are molluscs which have a head,
and move by means of a fleshy disc or foot placed under the
belly (Fig. 539), or of a fin formed by the same part of the
body (Fig. 543) : this class, which has as its type the snail,
is very numerous, and is composed chiefly of animals lodged

Fig. 539.— Helmet shell (Cassis).

in a single shell, having generally the form of a cone, or
rolled into a spiral ; some species are, on the contrary, en-
tirely naked, as the slug. The body is elongated, and ter-
L L 2

516

ZOOLOGY.

initiated anteriorly by a head more or less developed, in which
is the mouth, provided with fleshy tentacles, varying in num-
ber from two to six ; the back is covered with a mantle pro-
longed more or less backwards, under the form of a mem-
branous sac, and which secretes the shell ; finally, the belly
is covered underneath by the fleshy mass of the foot. The

vb ab ob ov

Fig. 540. — Anatomy of a Pectinibranchiate Gasteropodous Mollusc.*

viscera, lodged on the back, occupy the upper part of the
buckler or cone formed by the shell, "and remain always en-
closed in it ; but the head and foot project externally when
the animal unfolds itself for progression, and re-enter into
the last turn of the spire when they contract themselves ;

* Anatomy of the Turbo Pica, to show the arrangement of the respiratory
cavity : — p, the foot of the animal ; o, operculum ; t, the proboscis ; in, the
tentacles ; y, the eyes ; m, the mantle, cleft longitudinally, so as to open the
respiratory cavity ; f, anterior edge of the mantle, which, in the natural
position, covers the back, and leaves an opening or large fissure by which the
water reaches the gills ; b, the gills ; vb, the branchial vein proceeding to the
heart (c) ; ab, the branchial artery ; a, the anus ; i, the intestine ; c, sto-
mach and liver ; ov, the oviduct. Above the nucha is the cephalic nervous
ganglion and the salivary glands : — d, fringed membrane bordering under-
neath the left side of the opening of the respiratory cavity.

CLASS OF THE GASTEROPODA. 517

thus, the size of this last part of the shell and the form of the
opening are in relation with the size of the foot. In most
aquatic gasteropodous mollusca in which the shell is spiral,
there exists a horny or calcareous disc, named operculum
(Fig. 540, 0), which is fixed to the posterior part of the foot,
and which closes the entrance of the shell when the animal
retires within it.

§ 607. The heart is always aortic, and is composed of a
ventricle and an auricle; it is found near the back of the
animal, on the opposite side to that occupied by the repro-
ductive organs. The arterial system is in general well de-
veloped (Fig. 53) ; but the venous system is always more or
less incomplete, and sometimes is altogther wanting, so that
the blood returns from the different parts of the body towards
the respiratory organs only by traversing the lacunaB or
spaces existing between the organs. It is also to be observed,
that the abdominal cavity, in which are lodged all the viscera,
is always thus traversed by the venous blood.

•- 1

p

Fig. 541.— The Pleurobranchus.*

The organs of respiration are formed sometimes for an
aerian respiration, sometimes for an aquatic life. In the first
case, they consist in a cavity, on the walls of which the blood-
vessels form a complicated network, into the interior of
which the air penetrates from without by an opening under
the external edge of the mantle. This kind of lung (Fig. 167)
is situated on the back of the animal, and is lodged in the last
turn of the spire of the shell when the mollusc is provided
with such a covering. In the gasteropoda destined to breathe
in water, the disposition of the gill varies ; these organs are
often enclosed in a cavity analogous to that constituting the
lung in the preceding (Fig. 540) ; but at other times they are

* m, the mantle raised up to show the gill (br) ; a, anus; J, mouth and
proboscis ; v, the veil; t, the tentacles ; p, the foot.

518

ZOOLOGY.

lodged between the mantle and the foot, or even on the back
of the animal, so as to float freely in the surrounding liquid;
as an example of the pulmonary gasteropodes, we may men-
tion the slug and snail, which live on the land ; the lymnseus
or helix (Fig. 166), the planorbis (helix vortex), and the

Fig. 542.— Eolis.

physa (the helix fontiualis), which live in stagnant waters, and
ascend to the surface to breathe the requisite air. Amongst
the gasteropodes provided with gills enclosed in a dorsal
cavity may be observed the volutes, the buccinures, the por-
celaines (Fig. 181), the heliotides, &c. The patellae and the

Fig. 543.— Carinaria.*

pleurobranchiaB (Fig. 541) carry these organs in the furrow
separating the foot from the mantle; and in the doris and the
eolis (Fig. 542), &c., they consist in bunches and in straps or
leashes fixed on the dorsal aspect of the body.

* b, mouth ; t, tentacles ; y, the eyes ; e> stomach ; ft liver ; a, anus ; c,
shell; br, gills; p, the foot; v, ventouse (cupping-glass-cavity air hole)
situated under the edge of the foot.

CLASS. OF THE PTEROPODA. 519

§ 608. The mouth of the gasteropodes is surrounded by con-
tractile lips, and sometimes armed with horny teeth occupying
the palate. In several other animals of this class the anterior
part of the gullet is very fleshy, and may be carried outwards
so as to form a proboscis. Sometimes the stomach is also
furnished with cartilaginous or osseous instruments adapted
to divide the food ; the intestine is turned on itself, and is
lodged between the liver and the ovary ; finally, the anus
(a, Fig. 540) is almost always situated on the right side of
the body, and is often found close to the head.

§ 609. In this class the organs of sensibility are less
developed than in the cephalopodes ; the tentacles which most
gasteropodes carry on their forehead serve only for touch,
and perhaps for smell. Their auditory organs consist only in
a pair of small membranous vesicles, and the eyes, which are
sometimes wanting, are very small, and of a very simple
structure ; they are sometimes adherent to the head, some-
times carried on the base, the side, or the point of the
tentacles. Finally, the nervous system is less developed than
in the preceding class, and is composed principally of a
cephalic ganglion, and of a thoracic ganglion re-united like a
collar around the gullet. Amongst these animals, some are
terrestrial, others live in fresh water, but most are marine.
In general they are formed to creep, as the slug, the limneus
(Fig. 166), the cowry (Fig. 181), &c. ; but sometimes
they are intended only to swim, as for example the carinaria
(Fig. 543).

CLASS OF THE PTEROPODA.

§ 610. The pteropoda are small molluscs having a dis-
tinct head, formed for floating and swimming by means of
two fins placed like wings on either side of the neck (Fig.
184). Some are naked, and others have a shell, but their
history is not of sufficient interest to induce us to dwell
longer on it.

CLASS OF THE ACEPHALA.

§ 611. The molluscs which we have hitherto been consi-
dering have all a distinct head; those which remain to be
spoken of are without it, arid show a greater simplicity in
their whole organization. Their body is entirely enveloped
by the mantle, like a book in its cover ; the skin of the back,
in fact, is adherent only in the middle, and forms on each

520

ZOOLOGY.

side a large fold, covering all the other part of the animal
(Pig. 544), and sometimes even is so united to its fellow of
the other side, as to leave openings only behind and before,
and to form two long tubes for the water necessary for respi-

m' a i f v

Fig. 544.— Anatomy of the Oyster.*

ration. A shell, composed of two valves, covers this mantle
in whole or in part, presenting superiorly a hinge, provided
with an elastic ligament, by the play of which the valves are
opened whenever the muscles, extending from one to the other,

Fig. 545.— Tellina.

cease to act. The viscera are collected into a small mass,
under the dorsal part of the mantle, and the ventral portion of

* v, one of the valves of the shell ; v', the hinge; m, one of the lobes of the
mantle; m, portion of the other lobe, laid upwards; c, muscles of the shell;
br, the gills ; b, the mouth ; I, labial tentacles; f, the liver ; it the intestine ;
a, the anus ; co, the heart.

CLASS OF THE ACEPHALA.

521

the body is generally prolonged so as to form a fleshy foot,
having some analogy with the gasteropodes, but not so well
formed for locomotion. Sometimes it is the inner surface of
the mantle, as in the terebratulse, which takes the place of
the respiratory organ, and for this purpose shows a highly
developed vascular network; but in general there exists a
very well developed branchial apparatus, composed of two
pairs of large membranous plates, finely striated, and floating

Fig. 546.— Pearl oyster.

Fig. 547. — Buccardium.

Fig. 548— Shell of the
Terebratula.

Fig. 549.— The Animal of the
Terebratula.

between the foot and the mantle (Fig. 544). The mouth is
also concealed between the folds of the mantle, and is found at
one of the extremities at the base of the abdomen ; it has
never any teeth, but is furnished laterally with two pairs of
labial prolongations, constituting laminated tentacles. The
stomach is sufficiently developed, and the intestine forms
around the liver circumvolutions before reaching the posterior

522 ZOOLOGY.

edge of the base of the abdomen, where it terminates. The
heart is generally situated above the visceral mass thus formed
(Fig. 183), and is composed of an aortic ventricle, and of one
or two auricles, destined to receive the blood from the gills,
In general this ventricle is fusiform, and presents a remark'
able peculiarity, its cavity being traversed by the rectum.
Finally, the nervous system consists chiefly of two pairs of
small ganglions, re-united by cords, but very distant from
each other, and placed the one above the mouth, the other
under the extremity of the intestine. The functions of rela-
tion are extremely limited, and most of these molluscs can
with difficulty displace themselves by pushing with the foot,
or rapidly shutting their shell to eject the water enclosed
between the valves, which gives to their body the returning
shock ; in general they live at the bottom of the waters, or
buried in the sand, and some fix themselves to rocks by
means of a bundle of horny or silky filaments, which spring
from the foot, and is called the byssus.

§ 612. This class is divided, according to the presence or
absence of lamellated branchise, into two orders. The lamelli-
branchiata, which comprise oysters, muscles, pearl oysters
(Fig. 546), the pectens (clams), the mactrse (Fig. 183), the
bucardia (Fig. 547), the solens or knil'e handles, the teredo,
&c. The brachiopoda owe their names to two kinds of fleshy
arms, which replace the foot ; the terebratulae (Figs 548 and
549) present this kind of structure.

SUB-DlVISION

^
OF THE MOLLUSC01DES, OR TUNICATA.

§ 613. The animals which we re-unite here are considered
by most zoologists as entitled to be arranged, some amongst
the molluscs, others amongst the zoophytes ; but this opinion
seems to depend on the imperfection of the knowledge pre-
viously had of the structure of these beings, but now that
anatomy and physiology are better known, and have been
better studied, it may be seen that they are all formed on the
same general plan, and that they establish in some measure
the passage between the mollusca properly so called, and the

OF THE MOLLUSC01DES, OR TUNICATA.

523

zoophytes. They all have a distinct digestive tube, turned on
itself, and open at both extremities, and have a very well
developed branchial apparatus (Fig. 551) ; most of them also
present vestiges of a nervous system, but have no ganglionary
ring like the mollusca, properly so called ; finally, almost all
multiply by granul ttions as well as by ova, and thus form
aggregations of* individuals more or less completely confounded
with each other.

These animals are all aquatic, and are formed on two prin-
cipal types — the tunicata, properly so called, and the bryozo-
aria or ciliated polypi.

Fig. 550.— Plumatella.*

§ 614. The tunicata, properly so called, are provided with
a very large mantle, in the form of a sac (Fig. 551), which
constitutes in front of the abdomen or visceral mass a respi-
ratory cavity, enclosing branchia?, variously arranged. They
have a heart, and bloodvessels, in which the nourishing liquid
circulates in a very singular manner, for the current changes

* a, group of the plumatellae of the natural size ; b, others magnified, and
seen in different positions ; c, termination of the intestine.

524

ZOOLOGY.

its direction periodically, so that in the space of some minutes
the same canal performs the function of an artery and a vein.

Fig. 551.— Biphore (Biphora.)*

In this class are arranged the biphores (Fig. 551), the pyro-
soma, and the ascidise (Fig. 180), distinguished into simple

* 5, mouth ; a, anus ; m, muscular bands surrounding 'the great pharyn-
geal or respiratory cavity; br, gills ; et visceral mass, including the stomach,
fiver, &c.; c, the heart.

THE ZOOPHYTES. 525

and aggregated. These last have often a phytoid appear-
ance.

The history of the biphores presents a very remarkable
peculiarity. Successive generations do not resemble each
other, but are composed alternately of aggregated and solitary
individuals. The first are hermaphrodite, and produce each
a younger one, which lives isolated, but which has no repro-
ductive organs, and gives birth, by granulation, to a sort of
chain of aggregated individuals. These singular animals are
sufficiently common in the Mediterranean.

§ 615. The bryozoaria, which even very lately have been
confounded with the more simple polypi, have the mantle less
developed, and the gills exposed. The organs consist in a
crown of tentacles, which surround the mouth, and which have
laterally vibratile cilia (Fig. 550). The anus is near the
mantle, and the blood arrives between the viscera and the
mouth, as well as in the interior of the tentacles, but is not
set in motion by a heart. Finally, the inferior portion of the
mantle is generally hardened, so as to form a tube or cellule,
sometimes horny, sometimes calcareous, into which the animals
may retire altogether. In general these beings, so small as
to be almost microscopic, live reunited in masses more or less
considerable. Most of them dwell in the sea, but some live
in fresh waters. Amongst these last we may mention the
alcyonellse, the plumatella (Fig. 550), common enough in our
stagnant waters, and amongst the first, the flustra, the
retepora and the vesicularia.

PKIMAKY DIVISION.
THE ZOOPHYTES.

§ 616. In this, the fourth and last primary division of the
animal kingdom, the organization is much less complete than
in most other animals ; and the different parts of the economy,
instead of being disposed in pairs on each side of a longitudinal
plane, are grouped around an axis or central point, so as to
give to the whole of the body a radiated or spherical form.
The nervous system is either rudimentary or wanting ; and
there are no special organs of sense, unless it be certain small
coloured spots, bearing some analogy to the eyes of the

526 ZOOLOGY.

mollusca. In structure, these animals differ widely from each
other; and, externally, some more resemble plants than

Fig. 552. — The Echinus, or Sea Hedgehog.*

animals. They have been divided into five classes — the
echinodermata, the acalepha, the polyps^ the infusoria
polygastria, and the sponges.

CLASS OF THE ECHINODERMATA.

§ 617. The echinodermata (Figs. 159 arid 186) are radiated
animals whose skin is thick, and often supported by a solid
skeleton (Fig. 552), with a very complex internal structure.
They are formed to creep along the bottom of the waters,
and are in general provided with a number of small retractile
tentacula, which pass through pores in the integuments, and
act by their extremities like suckers. In most zoophytes,
the sea urchin and holothuria for example, the digestive
cavity has the form of a tube, open at its two extremities ; and
in others (the sea stars) it consists only of a sac, furnished
all around with a number of appendages, more or less branched,
with a single aperture communicating externally. Theechino-

* On the left side the spines have been removed to show the shell.

CLASS OF THE ECHINODERMATA. 527

dermata have a circulatory apparatus sufficiently developed ;
and of all the zoophytes are those whose organization is most
complex and most perfect. They live in the sea, and when
young undergo some remarkable metamorphoses. The echino-

Fig. 553. — Encrinus ; Sea Lily.

dermata form three principal groups — the holothuria (Fig.
554), the echinus (Fig. 552), and the asterias or sea star (Fig.
159). Some species of this last family attach themselves by
a sort of stalk. Such are, or rather were, the encrinidae

528 ZOOLOGY.

(Fig. 553), now rarely met with, but which once existed in
great numbers in the seas of various geological epochs. The
holothuria are remarkable for the disposition of their respira-

Fig. 554— Holothuria; Sea Cucumber,

tory apparatus, composed of membranous tubes ramified like
a tree, and receiving water into the interior through the
intermedium of a cloaca or anus.

CLASS OF THE ACALEPH^.

§ 618. The acalephse are soft animals, of a gelatinous
consistence, always floating in the sea, and formed essentially
for swimming. Their organization is very simple ; the skin
is not distinct from the subjacent parts, and their internal
organs are reduced to a cavity or stomach, communicating
with the exterior by a single opening, and giving rise to
canals extending into the different parts of the body, and
there ramifying, so as to give a resemblance to a vascular
system.

The family of this class which is best known is that of the
medusae, amongst which are the rhizostomes (rhizostomatidse),
which abound on the coast, and which are remarkable for the
singular disposition of the digestive apparatus, the stomach
communicating externally by a great number of small canals,
terminated by pores at the free extremity of the tentacles.
In this class are included the heroes (of the class ciliograda)

CLASS OF THE ECHINODEBMATA. 529

which resemble small balloons ; the cestidse, which have the
form of a long gelatinous ribbon ; and the phj'sophoridse,
which have the appearance of a garland of flowers and
fruits *

The medusa produce eggs like most animated beings, but
the young which spring from, these in no shape resemble the
mother; they are small ovoid bodies, having their surface
provided with vibratile cilia, and which soon are fixed, and

Fig. 555.— Sea Blubber (Medusa Pelagica) ;
JeUy Fish.

as they become developed form zoophytes, already known to
naturalists by the name of hydroid polypi (sertularidse, for
example) ; these multiply by granulations, so as to constitute
colonies of aggregated animals ; and the different individuals
of the new generation thus produced become free as the}T are

* In this family, including the physalidse, the body is floated by air cells,
and locomotion performed by parts exposed to the wind. — R. K.
M M

530 ZOOLOGY.

developed, and metamorphosed into medusae. This succession
of individuals of two kinds, which alternately succeed each
other and present the same forms only at the second
generation, has been called metagenesis, or alternating gene-
ration.

CLASS OF THE COEALS, OK POLYPI PEOPEELY SO CALLED.

§ 619. Some confound under the name of polypi the
bryozoaria, of which we have already spoken in treating of the
molluscoids (§ 615), and the corals, or polyps properly so
called, which have a structure entirely different and much

Fig. 556. — Polyp of the genus Astroides; a Coral.

less complete. These are animals with a cylindrical body,
soft, and pierced at one extremity by a central mouth, sur-
rounded with tentacles, and without vibratile cilia (as Fig.
556).

This orifice holds the place of anus, and leads directly, or
by the intermedium of a membranous tube, into a large
cavity occupying all the body, extending superiorly into the
tentacles, and lodging the ovaria suspended to its walls. The
inferior extremity of the polyp is contracted, so as to adhere
to foreign bodies, on which the animal is destined to live
fixed to them ; its skin generally hardens to a large extent,
so as to form a horny or calcareous envelope, analogous to

CLASS OF THE COBALS, OB POLYPI.

531

the cellules of which we have already spoken in describing
the bryozoaria. The polyps properly so called, resemble also
the molluscoids by their mode of multiplication ; for most of
them not only reproduce by means of eggs, but also by means
of granulations, which spring from different parts of the sur-
face of their bodies and never become detached ; so that
different generations remain engrafted as it were on each
other, and form larger or smaller masses, in which all the
individuals of the same race are included, and live, up to a
certain point, a common life.

Fig. 557 *

Fig. 558.— Corallines.*

The portion, in some measure ossified, of the tegumentary
tunic of these polyps, presents varied forms, and constitutes
sometimes tubes, sometimes cellules. For a long period this
was considered merely as the dwelling of the polyps which
form it, and it is to it that the name of polypier has been
given. Sometimes each polyp has a distinct polypier, but
in general it is the common portion of a mass of aggregated
polypi which presents the characters peculiar to these bodies,
and thus these form aggregated polypier 8, the volume of
which may become very considerable, although each of its
constituent parts has dimensions which are very small.

§ 620. It is in this way that polyps with bodies only
some lines long raise, in seas adjoining the tropics, reefs and

* Figures not especially referred to in the text.
M M 2

532

islands. When they are placed in circumstances favourable
for their development, certain animals of this class multiply
so as to cover chains of rocks or immense submarine banks,
and to form, with the rocky masses of their polypiers heaped
together one above the other,
masses of which the extent in-
creases unceasingly by the birth
of new individuals, above those
already existing. The solid cover-
ing of each colony of polyps re-
mains untouched after its frail
architects have perished, and
serves as a base for the develop-
ment of other polypiers, until
the living reef reaches the surface
of the waters ; for then these
animals can no longer live, and
the soil formed by their debris
ceases to rise. But soon the
surface of these masses of poly-
piers, exposed to the action of
the atmosphere, becomes the seat
of a new series of phenomena;
grains deposited by the winds,
or floated thither by the waves,
germinate, and cover the mass
with a rich vegetation, until at
last these vast charnel-houses of
zoophytes almost microscopic, be-
come habitable islands. In the
Pacific Ocgan a number of reefs
and island's have no other origin.
In general they seem to have for
their base some crater of an ex-
tinct volcano, for they have almost
always a circular form, and pre-
sent in the centre a lagoon com-
municating externally by a single
channel : some are known to be
more than ten leagues in diameter.
§ 621. Almost all coral animals inhabit the sea; never-
theless some are found in fresh waters. Those which have
the coral case simply fleshy or horny, are spread over all

Fig. 559.— Polyps (Yeretilli);
Star-shaped Polyps, or Sea
Fans ; Asteroid Polyps.

OF THE CLASS INFUSORIA. 533

climates ; but it is only in the seas of hot climates, or nearly
so, that we find an abundance of the coral polyp with a rocky
covering or coral case.

Sometimes these aggregated polyps deposit in the interior
of the common tissue by which they are united, a horny or
calcareous matter, constituting a sort of interior stalk, which
branches out like a tree, in proportion as the animated mass
sends forth new branches. It is in this way that the coral
of commerce is formed (Fig. 189), of which such use is made
in the fabrication of ornaments : there is an active fishery for
this substance on the coast of Algeria.

The actiniae belong to this division of the animal kingdom ;
they are also called sea anemones (Fig. 168) ; they have a
fleshy body, and are found in great numbers on the rocks of
our coast; the caryophylli and the astreae, which, more than
all others, assist in the formation of coral reefs (Fig. 190) ;
the coral animal itself (Fig. 189) ; the veretilli (Fig. 559),
which do not adhere to the soil, but are simply buried in
the sand by one of the extremities of the common stalk,
belong to this division. Most zoologists also class with
them the hydra, of which we have already spoken (§ 347).

OF THE CLASS INFUSOEIA PROPERLY SO CALLED.*

§ 622. Those animalcules which can only be detected by
the microscope, or which, even to a late period, have been
confounded with the rotifera (§ 586), but whose structure is
very different, are developed in abundance in water containing
the remains of organized bodies. Their body, sometimes
rounded, sometimes elongated, is often covered with small
cilia, and offers in its interior a number, generally very con-
siderable, of small cavities, which seem to perform the func-
tions of stomachs. In some, these little enlargements seem
to be grouped around a canal which opens externally by
two extremities (Fig. 192) ; but at other times they seem to
be altogether isolated ; and persons who have made these
little beings the object of a special study, are not agreed as to
the existence of a direct communication between this cavity

* Many of the small beings which zoologists place in this group appear
rather to belong to the division mollusca than to that of ?oophytes; but
their natural affinities have not as yet been so clearly established as to enable
us to discuss this question here.

534 ZOOLOGY.

and the exterior. The mode of propagation of the infusoria
has been the object of ranch research, and a great many
naturalists think that they may be formed directly by the
disintegration of the matters of which leaves, flesh, and other
organized bodies are composed ; but this spontaneous genera-
tion is far from being sufficiently demonstrated, and it is
known that, in certain cases at least, they spring from each
other. Moreover, their mode of propagation is quite in
accordance with the simplicity of their structure : it is by the
spontaneous division of their body into two or more frag-
ments, each of which continues to live, and soon becomes a
new individual, resembling the first; thus it is that these
singular beings in general multiply.

Their forms are very varied, and they have been divided
into several genera, amongst which we may mention the
enchelides (in. Fig. 192), which have an oblong body ; the
volvoces, which are globular, and continually turn on them-
selves ; and the monads (i. Fig. 192), which resemble small
points whirling in the water in which they swim. It is owing
to the presence of myriads of a particular species of these small
monads, whose bodies are coloured red, that salt stagnant
waters or ditches acquire a sanguinolent colour.

CLASS OF THE SPONGIAKIA.

§ 623. The sponges (Fig. 191) and the other bodies of an
analogous structure, only present the more prominent cha-
racters of animality during the early period of their life, and
resemble later rather unformed vegetables than ordinary
animals. At the time of birth, these singular beings suffi-
ciently resemble certain infusoria; their body is oval, and
provided all over with vibratile cilia, by means of which they
swim in the waters ; in this respect the}1" bear a resemblance
to the larvse of different polyps at the moment when they
leave the egg ; but soon the young sponges attach themselves
to some foreign body, become almost immovable, give no
longer any signs of sensibility or of contractility, and as they
grow, become completely deformed. The gelatinous substance
of their bodies becomes pierced with holes and canals, tra-
versed unceasingly by the waters, and there is developed in
their interior a number of horny filaments and spiculse, some-
times calcareous, sometimes siliceous, which, disposed in cross
bundles .constitute a kind of solid framework. Finally, at

GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 535

certain epochs of the year there are developed in the sub-
stance of these shapeless masses, ovoid or spherical corpuscles,
which fall into the canals already mentioned, and which,
drawn outwards by the current by which the sponge is
constantly traversed, constitute species of larvae or reproduc-
tive bodies, endowed with the locomotive faculty mentioned
above.

A great number of these sponges, or spongiaria, are known
to naturalists ; most of them belong to the seas of warm
regions, but several live on the rocks of our coast. Those
used so abundantly in domestic economy are distinguished by
the purely horny nature and by the elasticity of the filaments
of which their solid framework is composed ; one of the
species, the common sponge, is found in great abundance in
the Mediterranean ; another, called usual, belongs to the
American seas. These bodies are the object of an important
commerce, and to prepare them for the uses to which they are
destined it is sufficient to wash them well, so as to detach from
their horny skeleton the animal matter with which it is
naturally covered.

OF THE GEOGRAPHICAL DISTRIBUTION
OF ANIMALS.

§ 624. To form a general idea of the animal kingdom, it
is not sufficient merely to know the principal phenomena by
which life manifests itself in animated beings, and to have
studied the structure of their bodies and the mechanism of
their functions ; it is also necessary to take a comprehensive
and general view of the manner in which animals are spread
over the surface of the globe, and to endeavour to appreciate
the influence exercised, or which may be exercised, over them
by the various circumstances in the midst of which they are
destined to live.

§ 625. When we direct our attention to the manner in
which animals are distributed around us on the globe, we are
at first struck with the difference of the media in which they
live. Some, as every one knows, live always under the
waters, and die speedily when they are removed from this
liquid ; others can live only in air, and perish so soon as they
are immerged. Some, in fact, are destined to people the
waters, others to live on land ; and when we compare, physio-

536 ZOOLOGY.

logically and anatomically, these aquatic and terrestrial
animals, we discover, at least in part, the causes of these
differences in their mode of existence.

In studying respiration, we have pointed out a constant
relation between the intensity of this function and the vital
energy. Animals, we have said, consume in a given time an
amount or quantity of oxygen always the more considerable
that their movements are more lively and their nutrition more
rapid. Now, they can only obtain this oxygen in the fluids
with which their bodies are bathed, and in a litre of air
(1760773 pints) there exist 208 cubic centimetres (eighty
cubic inches, nearly) of this vivifying principle ; whilst in a
litre of water there exist dissolved merely about thirteen cen-
timetres (five cubic inches). It is evident, then, that the
degree of activity in the respiratory function, indispensable to
the exercise of the faculties peculiar to the superior animals,
ought to be much more easily attained in air than in water,
and that by reason of this difference^alone a stay or residence
in this latter fluid must be and is interdicted to all the more
elevated beings in the animal scale. It is readily compre-
hended, in fact, that an animal which, in order to live, requires
to appropriate to itself at every instant a considerable quan-
tity of oxygen, cannot find it in sufficient proportion when
plunged under water, and that then it must perish asphyxiated.
But, at first view, it seems less easy to explain the causes by
which an aquatic animal cannot continue to live when with-
drawn i'rom the water and placed in air, for it is then furnished
with a liquid richer in oxygen than was the liquid, the vivify-
ing action of which sufficed for all its wants. There are, how-
ever, various circumstances which, to a certain point, explain
chis phenomenon. Thus we learn by physics (natural philo-
sophy), that a body weighed successively in air and water, is
lighter in this latter than in the former, and that to maintain,
it in equilibrium, a weight equivalent to that which repre-
sented its weight in air, less that of the mass of water it has
displaced, is then sufficient. From this it results that ani-
mals whose tissues are too soft to support themselves in the
air, and which collapse to such a degree as to become unfit to
perform their functions in the organism, may yet live well in
the bosom of the waters where these same tissues, being
scarcely denser than the surrounding fluid, have occasion to
offer merely a feeble resistance to preserve their forms, and to
preserve the different parts of the body from collapsing on

GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 537

themselves. This single consideration suffices to explain
why gelatinous animals, such as the infusoria and medusae,
are necessarily confined to the waters ; for when we observe
one of these delicate beings still plunged in this liquid, we.
see that all its parts, even the most slender or delicate, sup-
port themselves in their normal position, and float with ease
in the surrounding medium ; but, so soon as we withdraw
them from it, their whole body collapses, and presents to the
eye merely a shapeless and confused mass. The influence of
the density of the surrounding medium on the mechanical
play of the instruments of life makes itself also felt on
animals whose structure is more perfect, but in which, how-
ever, respiration is performed by ramified membranous appen-
dages, like little brushes or bunches of feathers. Thus in the
aimelides, or even in fishes, the branchiae or gills are composed
of flexible filaments, which support themselves easily in the
midst of water, and in this way permit the respirable fluid to
reach, and to 'be renewed at all points of their surface ; but in
the air these same membranous filaments collapse by the
effect of their own weight, fall on each other, and by that
alone exclude the oxygen from the greater part of the respi-
ratory apparatus. From this it results that this function is
then shackled, and that the animal may die asphyxiated in
the air, whilst he found in water that which, he required to
breathe freely. To be convinced of the importance of these
variations in the physical condition of organs placed in air or
in water, it is sufficient to recal what takes place in our prac-
tical or dissecting-rooms. An anatomist desirous of study-
ing the structure of a delicate part, would attain his object
with difficulty, if he made his dissection with the part exposed
simply to the air ; but by placing under water the object of
his study, he is thereby enabled to distinguish much more
readily all its parts ; for these parts, supported in some mea-
sure by the liquid, preserve then their natural relations as if
they had a rigid and consistent tissue. Another circum-
stance which has an equal influence over the possibility of
life in air or in water, is the evaporation which always takes
place from the surface of the organized bodies when placed in
air, but which does not happen in water. A certain degree
of desiccation causes all organic tissues to lose their distin-
guishing physical properties, and we constantly observe that
losses by evaporation cause the death of animals when it goes
beyond certain limits. It results from this, that beings

538 ZOOLOGY.

whose organization is not calculated so as to preserve them
from the injurious effects of such an evaporation, can live
only in water, and perish promptly in the air. Now the
animal economy can only meet this exigency by means of a
great complication in its structure. In fact, if the respira-
tion must be active, it becomes necessary that the respiratory
surface be then lodged profoundly in some internal cavity
where the air can only be renewed in the quantities necessary
for the support of life. To secure this renewal, it is essential
that the respiratory apparatus be complicated with motor
organs proper to secure it ; to prevent the desiccation of any
portion of the surface of the body, it becomes necessary also
that the distribution of the liquids in the various parts of the
body be accomplished easily, and that there exist an active
circulation, or otherwise that this surface be clothed with a
tunic scarcely permeable. This is so true, that even in fishes,
in which the circulation is so complete, but takes place
slowly, and in which the capillary network is not very close,
death takes place rapidly, as a necessary consequence of
the desiccation of a part of the body — of the posterior por-
tion, for example — even when this portion alone is exposed
to the air, all the rest of the animal remaining plunged under
water.

We might also add, that in water, alimentation is possible
with instruments of prehension and of motion less perfect
than in air, in which the transport of foreign matters re-
quired by the animal is more difficult to accomplish. Thus,
under all its more essential relations, life is, in some measure,
easier to sustain in the bosom of the waters than on the sur-
face of the dry land ; it necessitates in the atmosphere phy-
siological instruments more complex and more perfect;
therefore the waters are the natural element of the animals
placed lower in the scale of the zoological series ; and if the
productions of the creation have succeeded each other in the
same order of the transitory conditions through which each
animal passes during the period of its development, we may-
conclude that it was in the middle of the waters that ani-
mated beings appeared first, a result which accords with the
observations of geologists and the assertions of Scripture. The
physiologist may in this manner give an account of the actual
mode of distribution of animals between the two geological
elements which divide the surface of the globe, land and
water: but these fundamental differences are not the only

GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 539

ones which we observe in the geographical distribution of
animated beings. If a naturalist familiar with the fauna of
this country, visit distant regions, he sees, in proportion as he
advances, the earth peopled with animals new to him, and
these species next disappear in their turn to make room for
other species equally unknown to him. If, quitting France,
he lands in South Africa, he will find but a very small num-
ber of animals similar to those he had seen in Europe, and he
will observe, especially, the large-eared elephant, the hippopo-
tamus, the double-horned rhinoceros, the giraffe, innumerable
flocks of antelopes, the zebra ; the Cape buffalo, whose horns
cover by their large base all the forehead ; the black-maned
lion ; the chimpanzee, which, of all animals, most resembles
man ; the cynocephalus, or dog-faced ape ; peculiar species of
vultures ; a number of bright-plumaged birds, strangers to
Europe ; insects equally different from those of the north, the
fatal termites, for example, which live in numerous societies,
and build of the soil habitations of considerable elevation
and most singular construction.

§ 626. If our zoologist quits the Cape of Good Hope and
penetrates into the large island of Madagascar, he will there
find a still different fauna. There he will no longer observe
the large quadrupeds he found in Africa, and the family of
the apes will be replaced by other mammals, equally well
formed to climb trees, but more resembling the carnivora,
and called by naturalists the Makis : he will meet with the
Aye-aye, an animal of the most singular nature, which seems
to be the object of a sort of veneration on the part of the in-
habitants, and which is essentially a true Quadrumanous
animal ; the tenrecs, small insectivorous mammals, which
have the back protected with spines or quills, like our hedge-
hogs, but which yet do not roll themselves up into a ball ;
the cleft-nosed chameleon, and several curious reptiles not
found elsewhere, as well as insects no less characteristic of
this region.

§ 627. Still travelling onwards and arriving in India, our
traveller will find an elephant distinct from that of Africa ;
oxen, bears, rhinoceroses, antelopes ; stags, equally different
from those of Europe and of Africa ; the oran-outan, and
a number of other apes peculiar to these countries ; the royal
tiger, the argus, the peacock, the pheasant, and an almost
innumerable multitude of birds, reptiles, and insects unknown
elsewhere.

540 ZOOLOGY.

§ 628. Should he afterwards visit New Holland, still
everything will be new to him, and the aspect of this fauna
will appear to him still more strange than that of the various
zoological populations he had already passed in review. He
will then no longer find animals analogous to our oxen,
horses, hears, and to a great number of our large carnivora :
the quadrupeds of great stature will be found totally wanting,
and he will discover the kangaroo, the flying phalanger, and
the ornithorhynchus.

§ 629. Finally, if our traveller, in order to return to his
native country, should traverse the vast continent of America ;
he will discover there a fauna analogous to that of the Old
World, but composed almost entirely of different species : he
will there find apes with prehensile tails ; large carnivora,
sufficiently resembling our lions and tigers, bisons, lamas,
tatous ; finally, birds, reptiles, and insects, equally remark-
able, and equally new to him.

§ 630. Differences no less striking in the species of ani-
mals peculiar to different regions of the globe, are observable,
when, instead of confining our observation to the inhabitants
of the land, we examine the myriads of living beings which
live in the midst of the waters. In passing from the coast of
Europe into the Indian Ocean, and from this last into the
seas of America, we meet with fishes, molluscs, Crustacea, and
zoophytes peculiar to each of these parts of the sea. This
localization of species, whether aquatic or terrestrial, is so well
marked that a naturalist a little experienced cannot mistake
at the very first sight the origin of zoological collections made
in one or other of the great geographical divisions of the
globe which may be submitted to his examination. The fauna
of each of these divisions presents a peculiar aspect, and may
be easily characterized by the presence of certain species, more
or less remarkable.

§ 631. Naturalists have imagined several hypotheses to
explain this mode of distribution of animals on the surface of
the globe ; but in the actual state of science it is impossible
to give a satisfactory explanation, unless we admit that from
the beginning of the actual geological period the various
species have been distributed in the different regions, and that
by degrees they have afterwards spread to a distance, so as to
occupy a more or less considerable portion of the surface of
the globe. In the actual condition of the globe, it is impos-
sible for us to discover all the zoological focuses ; for one may

GEOGEAPHICAL DISTEIBUTION OF ANIMALS. 541

imagine the possibility of exchange so multiplied between
two regions, the faunae of which were primitively distinct,
that they can only now offer at the present moment species
common to both, and thus nothing can reveal to the eyes of
the naturalist their original separation : but when a country
is found to be peopled with a considerable number of species
not to be found elsewhere, even where the local circumstances
most resemble, we shall be authorized to think that such a
portion of the globe has always been a distinct zoological
region.

[Buffon was the original author of the great practical thought
or theory included in the preceding paragraph ; he it was who
discovered and first spoke of " centres of creation." It has been
ascribed by some English writers to a former student of mine,
Mr. E. Forbes, who assuredly never claimed it in his own name.
But he ought to have disavowed it when ascribed to him by
.others, whose motives for doing so may very readily be guessed
at.

M. Schlegel, in his admirable work on the Physiognomy of
Serpents, has written a memoir on this subject, which I should
with much pleasure have added to this work, were it not that the
subject in reality belongs to the philosophy of zoology, a matter
which the author does not profess to treat of in this valuable
elementary work ; from it, however, I give the following passage,
reminding the reader that the work was written at least twenty
years ago.

" By cultivation the earth loses its primitive aspect. Serpents
are peculiar in many respects, and their natural history is emi-
nently calculated to elucidate the great questions of foci or centres
of creation, and the immutability of species." (p. 197.) The
ophidians of Japan are distinct from all others ; so also are those
of Madagascar. " SCHLEGEL. — E. K.]

What the naturalist ought to inquire into is, not how it
happens that the various points of the globe are inhabited at
the present day by different species, but rather how these
animals have been able to spread themselves to a distance
over the surface of the globe, and how nature has set to this
diffusion variable limits, according to the species. This last
question especially presents itself to the mind, when we
observe how unequal is the extent of the domain occupied by
different animals. The oran-outan, for example, confined
to the Island of Borneo and the neighbouring territories ; the
musk-ox, limited to the most northern parts of America,
and the llama, to the elevated regions of Peru and of Chili ;

542 ZOOLOGY.

whilst the wild duck is found everywhere, from Lapland to
the Cape of Good Hope, and from the United States of
America to China and Japan.

The circumstances which favour the dissemination of spe-
cies are of two kinds. The first is connected or dependent on
the nature of the animal itself; the second, with causes foreign
to it. In the number of the first, the development of the
locomotive power holds an important place. All things being
equal, the species which live fixed to the soil, or which possess
but imperfect instruments for locomotion, occupy but a re-
stricted portion of the surface of the globe, compared with
species whose movements of translation are rapid and ener-
getic. Thus, amongst terrestrial animals, birds offer us most
examples of cosmopolitan species ; and amongst the aquatic
animals, cetacea and fishes. Reptiles, on the contrary, are
generally cantoned on narrow limits ; and the same may be
said of most of the molluscs and of the Crustacea. The in-
stinct which leads certain animals periodically to change their
climate, contributes also to cause the dissemination of species ;
and this instinct, as we have already seen, exists in a great
number of these beings. Amongst the circumstances foreign
to the animal, and in some measure accidental, concurring to
bring about the same result, the influence of man may be
placed foremost ; and to give of this an exact idea, it will be
sufficient to mention a few species. The horse originally
belonged to the steppes of Central Asia ; and at the epoch of
the discovery of America, there did not exist in the New
World an individual of the species. The Spaniards trans-
ported the horse with them at an epoch which does not
ascend beyond three ages ; and in our day, not only the in-
habitants of this vast continent, from Hudson's Bay to Terra
del Fuego, possess horses in abundance, but these animals
have even recovered their wild condition, and are found in
troops almost innumerable. It is the same with our domestic
ox. Carried from the Old to the New World, they have in-
creased to such an extent, that in some parts of South America
they are hunted solely with a view to obtain the hides for the
manufacture of leather. The dog also has been everywhere
the companion of man ; and we may add to the number of
animals become cosmopolitan in our time, the rat, which
seems originally to have been American, which entered
Europe in the Middle Ages, and may now be found even in
the isles of Oceanica.

GEOGRAPHICAL DISTEIBUTION OF ANIMALS. 543

In some instances animals have been able to burst natural
barriers seemingly insurmountable, and to spread themselves
over a more or less considerable portion of the surface of the
globe by means of circumstances which at first sight seem
extremely unimportant, — such as the movement of a fragment
of ice, or of a morsel of wood swept along by currents to dis-
tances often very considerable : thus nothing is more common
than to meet at sea, at a distance of hundreds of leagues from
all land, fuci floating on the surface of the water, supporting
small Crustacea incapable by themselves of removing by
swimming to any great distance from the coasts where they
were produced. The great maritime current which, leaving
the Gulf of Mexico, coasts along North America as high as
Newfoundland, then directs itself towards Iceland and Ireland,
and redescends towards the Azores, often carries with it, even
to the coasts of Europe, trunks of trees, which the Mississippi
has torn away from parts the most remote of the New World,
and carried to the sea. Now these timbers are often bored
by the larvse of insects, and may give attachment to the eggs
of mollusca, insects, &c. Finally, even birds contribute to
the dispersion of living beings over the surface of the globe,
and that in a most singular manner ; these animals often do
not digest the eggs they swallow, and, discharging them at
considerable distances from the place where they had found
them, transport to a distance the germs of a race unknown
to that time in the countries where they have been deposited.
Notwithstanding these means of transport, and of other cir-
cumstances equally calculated to favour the dissemination of
species, there are really very few animals cosmopolitan, and
most of these beings are cantoned in regions sufficiently limited.
Moreover, we comprehend why it should be so in studying
the circumstances which may oppose their progress. But
this study is far from furnishing us with a sufficient explana-
tion of the limited circumscription of a species, and it is often
impossible for us to divine why certain animals remain con-
fined to a locality when there seems to be nothing opposed to
their propagation in neighbouring districts.

§ 632. However this may be, the obstacles to the geo-
graphical dissemination of species are sometimes altogether
mechanical, at other times physiological; and amongst the
first we may mention seas and high chains of mountains.
For terrestrial animals, in fact, seas of a certain extent form in
general an insurmountable barrier ; and we see that, all things

544 ZOOLOGY.

being equal in other respects, the mixture of two distinct
faunae is always the more intimate that the regions to which
they belong are more geographically approximated, or are
placed in communication by intermediate lands. Thus the
Atlantic Ocean prevents the species proper to Tropical Ame-
rica from spreading into Africa, Europe, and Asia ; and the
fauna of the New World is completely distinct from that of
the Old, unless it be in the more elevated latitudes towards
the northern pole ; but there the lands approach : America is
only separated from Asia by the straits of Behring, and holds
relations with the north of Europe through Greenland and
Iceland; thus zoological exchanges could take place much
more easily, and it is there, in fact, that we find the species
common to the two worlds, — such as the white bear, the rein-
deer, the beaver, the ermine, the pelerine falcon, the white-
headed eagle, &c. Lofty chains of mountains constitute also
natural barriers which often arrest the dispersion of species,
and prevent the fusion of faunae peculiar to neighbouring
zoological regions. Thus the two slopes of the Cordilleras of
the Andes are inhabited by species generally distinct ; and
the insects of Brazil, for example, are almost all distinct from
those we meet with in Peru or in New Granada. The dis-
persion of marine animals living near the coast is shackled
in the same way by the geographical configuration of the
globe ; but here it is sometimes a long contiguity of land,
sometimes a vast extent of the deep sea, which opposes itself
to the dissemination of species. Thus most of the animals
of the Mediterranean are also found in the European portion
of the Atlantic, but have not been able to reach the Indian
seas, from which the Mediterranean is separated by the isthmus
of Suez ; nor to traverse the Atlantic Ocean, to spread them-
selves on the coasts of the New WorM.

§ 633. The physiological circumstances which tend to
limit the different faunae are more numerous; but that which
presents itself in the first place is unquestionably the unequal
temperature of the different regions of the globe. There are
species which can support equally well an intense cold and
tropical heat ; man and the dog, for example ; but there
are others which in this respect are less favoured by nature,
and which do not prosper, or even cannot exist, but under the
influence of a fixed temperature « Thus the apes which crowd
the tropical regions almost always die of phthisis (pulmo-
naiy consumption) when they are exposed to the cold and

GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 545

humidity of our climate; whilst the reindeer, formed to support
the rigours of a long and rude Lapland winter, suffers from
heat at St. Petersburg, and in general sinks quickly under
the influence of a temperate climate. From this it results
that, in a great number of cases, differences in climate alone
are found to be sufficient to arrest the march of species from
high latitudes towards the equator, or from equatorial regions
towards the poles. The influence of temperature on the ani-
mal economy explains to us also why certain species remain
cantoned in a chain of mountains without being able to spread
abroad into analogous localities. We know, in fact, that the
temperature decreases by reason of the elevation of the soil,
and that in consequence animals which live at considerable
elevations could not descend into the low plains to reach
other mountains, without traversing countries where the tem-
perature is much superior to that of their ordinary habita-
tion. The genus llama, for example, abounds in the grassy
countries of Peru and of Chile, situated at an elevation of four
or five thousand metres (from four to five thousand yards)
above the level of the sea, and extending to the south as far
as the extremity of Patagonia ; but they are to be found neither
in Brazil nor Mexico, because they could not arrive there with-
out descending into regions too hot for their constitution.

The nature of the vegetation and of the pre-existing fauna
in a region of the globe equally influences its appropriation
by exotic species. Thus the dispersion of the silkworm is
limited by the disappearance of the mulberry above a certain
degree of latitude ; the cochineal cannot spread itself beyond
a region where grows the cactus ; and the large carnivora,
unless they live on fish, cannot exist in the polar regions,
where the vegetable productions are too scant to support a
considerable number of herbivorous quadrupeds.

§ 634. It were easy for us to multiply examples of these
necessary relations between the existence of an animal species
in a given locality, and the existence of certain climatic,
phytological, or zoological conditions ; but we want space for
such details, and the considerations we have just givsn appear
to us sufficient to give an idea of the manner by which nature
has accomplished the repartition of animal species over dif-
ferent points of the surface of the globe ; and to attain the
end we proposed in touching on this subject, it only remains
for us to take a view (coup d'ceil) of the results brought
about by the different circumstances of which we have just

N N

546 ZOOLOGY.

spoken, that is to say, of the actual condition of the geo-
graphic distribution of animated beings. When we compare
the various regions of the globe with each other in the rela-
tion of their zoological population, one is struck at first with
the extreme inequality observable in the number of species.
In a certain country, for example, we meet with an extreme
diversity in the forms and the structure of the animals com-
posing its fauna, whilst elsewhere there reigns in this respect
a great uniformity ; and it is easy to observe a certain relation
between the different degrees of zoological richness and the
elevation, more or less considerable, of the temperature. In
fact, the number of species, as well marine as terrestrial, aug-
ments in general in proportion as we descend from the poles
towards the equator. The more remote polar regions offer to
the traveller only a few insects, and in its icy seas the fishes
and the mollusca themselves are but little varied ; in tem-
perate climates the fauna becomes more numerous in species ;
but it is in the tropical regions that nature shows herself
most prodigal in this respect, and the zoologist cannot see
without astonishment the endless diversity of animals which
are accumulated there.

It is remarkable also that there exists a singular coin-
cidence between the elevation of the temperature in different
zoological regions, and the degree of organic perfection of the
animals inhabiting them. It is in the hottest climates that
we find the animals which mosfc approach man, and those
which in each great zoological division possess the orga-
nization the most complex, and the faculties most developed ;
whilst in the polar regions we meet only with beings occupy-
ing a rank but little elevated in the zoological series. The
apes, for example, are limited to the hottest parts of the two
continents; it is the same with the -parrots amongst birds;
the crocodiles, the turtles, and tortoises amongst reptiles, and
land- crabs amongst the Crustacea, — all animals the most
perfect in their respective classes.

It is also in hot countries that we find the terrestrial the
most remarkable for the beauty of their colours, the size of
their bodies, and the singularity of their forms.

Finally, there seems to exist a certain relation between the
climate and the tendency of nature to produce such or such
an animal form. Thus we observe a great resemblance be-
tween most of the animals inhabiting the Boreal and Austral
regions ; the faunae of the temperate regions of Europe, Asia,

GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 547

and North America offer a great analogy in their general
aspect ; and in the tropical countries of the two worlds we
see predominating similar forms. It is not that we find
identical species in regions distinct and nearly isothermal,
but species more or less neighbouring, and which seem to be
the representatives of one and the same type. Thus, the apes
of India and of Central Africa are represented in tropical
America by other apes, easily distinguished from the first ; to
the lion, the tiger, and the panther of the Old Continent,
correspond in the New World the puma, the jaguar, and
the ocelot. The mountains of Europe, of Asia, and of
Northern America nourish bears of different species, but still
presenting but slight differences. Seals abound especially in
the neighbourhood of the two polar circles ; and if we wish
to look for proofs of this tendency, not in the more elevated
classes of the animal kingdom, but amongst the inferior
beings, we shall find them no less evident ; the craw-fishes
and lobsters, &c., for example, appear to be confined to
the temperate regions of the globe, and are found spread
abroad throughout the greatest part of Europe, by the species
so common in our rivulets, in the south of Russia by a dif-
ferent species, in Northern America by two other species
equally distinct from the preceding, in Chile by a fourth
species, to the south of New Holland by a fifth, in Mada-
gascar by a sixth, and at the Cape of Good Hope by a
seventh.

The comparison of the faunae peculiar to the different zoo-
logical regions of the globe conducts to other results, of which
it is more difficult to give an explanation. Thus, when we
examine successively the whole of the species inhabiting
Asia, Africa, and America, there may be observed in the
fauna of the New World a character of inferiority which did
not escape the celebrated Buffon. In fact, there do not exist
in the New World mammals so large as in the old continents ;
we find indeed in Northern America a considerable number
of apes, but amongst these animals there are none equal to
the ourang and chimpanzee ; and it is rather the rodents and
the edentata which abound the most, that is to say, of all
ordinary mammals the least intelligent. Finally, it is in
America that we meet with the sarigues (opossums), animals
which belong to an inferior type of ordinary mammals, and
which have no representatives in Europe, Asia, or Africa. If
we pass afterwards from the New World to Australia, a still

NN2

548 ZOOLOGY.

newer region, we find a fauna the inferiority of which is still
more evident, for the class of mammals is there scarcely re-
presented by the marsupialia and the monotremes.

With regard to the delimitation of the different zoological
regions which divide the globe, and to the composition of the
fauna peculiar to each of them, we cannot treat of it here
without passing beyond the limits prescribed by this course of
instruction, and we the less regret this necessity seeing that
in the actual state of the science these questions are far from
being solved.

We shall even close here our zoological studies, for the
object we had proposed to ourselves was not the particular
description of each animal, nor the enumeration of the charac-
ters by which they might be known or grouped methodically ;
we only wish to give in this course ideas on the nature and
properties of these beings, to sketch rapidly the principal
traits of their history, and to furnish to our young readers
the general knowledge the most useful to all, and indispen-
sable to those who wish to study more deeply this branch of
the sciences of observation.

[The following tables of the Classification of the Animal
Kingdom are appended for the convenience of the student.
The first is that used in my Lectures at the London Institu-
tion in 1863 ; the second is founded on the classification of
Owen.— C. C. B.]

1. CLASSIFICATION OF THE ANIMAL KINGDOM.

Sub-kingdom VERTEBRATA.
Hamatotherma \
Hamatocrya

Sub-kingdom MOLLUSCA.

Sub- kingdom ARTICULATA.

Cephalopoda.
Gasteropoda.
Pteropoda.
Brachiopoda.
Conckifera.
Tunicata.

Insect a.
Arachnida.
Crustacea.
Cirripedia.
Annelida.
Entozoa.

Sub-kingdom EADTATA.

Bryozoa. AcalepJice. EcJdnodermata.

Anthozoa.
Hydrozoa.

Kingdom ACRITA, or PROTOZOA.

Infusoria.
Foraminifera .
AmorpJwzoa.

550

ZOOLOGY.

2. TABLE OF THE ORDERS OF VERTEBRATA.

Class MAMMALIA.
Sub-class ABCHENCEPHALA.

Order 1,
Sub-class

Order 2.
3.

4.
5.

6.

7,
8.
9.

Sub-class

Order 10.
„ 11,
„ 12.
, 13.

Bimana
GYKENCEPHALA.

Quadrumana
, Carnivora .
, Artiddactyla
Perissodactyla
Proboscidea
Toxodontia
Sirenia
Cetacea

LlSSENCEPHALA.

Brut a
Cheiroptera
Insectivora
Rodentia .

Sub-class LTENCEPHALA.

Order 14.
, 15,

Marsupialia
Monotremata

Class BIRDS.

Order 1. Raptor es .

2. Scansores .

3. Volitores .

4. Insessores .

5. It a sores

6. Cur sores

7. Grallatores

8. Natatores .

EXAMPLE.
Man.

Ape.

Lion.

Ox, Hog.

Tapir.

Elephant.

Toxodon (fossil).

Dugong.

Whale.

Armadillo.
Bat.
Mole.
Rat.

Opossum.
Platypus.

Eagle.

Parrot.

Swift.

Sparrow.

Turkey.

Ostrich.

Stork.

Duck.

TABLE OF THE OEDEES OF VEETEBEATA.

551

Class HJEMATOCRYA.

Sub-class EEPTILES.
Order 1. Batrachia
„ 2. Chelonia
,, 3. OpJiidia
„ 4. Lacertilia

5. Crocodilia.

6. Dinosauria

7. Pterosauria

8. Anomodontia

9. Sauropterygia

10. Ichthyopterygia

11. Thecodontia

12. Ldbyrinthodontia

13. Ganocephala

Sub-class FISHES.

Order 14. Plagiostomi .

„ 15. Holocephali

16. Protopteri

17. Placoganoidei

18. G-anoidei

19. LopJiobrancJiii

20. Plectognathi .

21. Acanthopteri .

22. Anacanthini .

23. Pharyngognathi

24. Malacvpteri .

25. Dermopteri

^

Tortoise.
Snake.
Lizard.
Crocodile.

Fossil forms.

Shark.

Chimaera.

Mudfish.

Coccosteus(fossil).

Bony pike.

Pipe fish.

File fish.

Perch.

Cod.

Parrot fish.

Herring.

Lamprey.

GLOSSARIAL INDEX.

PAGE

ABRAXAS Gr.t proper name 432

Absorption ... ... ... ... ... 11

Acalephae Gr., a nettle 528

Acephala Gr., headless 220,519

Actinia Gr., a ray 214

Agama ... 363

Aliments 18

Alpaca Quichua, proper name 289

Ammonite Egyptian, Amoun, the deity ... 515

Amphinome Gr., two houses 402

Amphioxus Gr., acute at both ends 231

Anabas Gr., climbing 383

Anatifa Gr., duck-bearing 491

Anchovy 392

Angora goat Angora, in Asia Minor 292

Anilocera ... ... Lot., the woodlouse ... ... ... 489

Animals, their general characters 6

heat 92

„ geographical distribution 535

Animal kingdom, classification of 227,544

Annelides Lat., annulus, a ring ... ... 401,497

Anteater 31

Anthropodaria Gr., man-footed 405

Anthropology ... ... Gr., science of man ... ... ... 259

Antilope canna Gr., antilope, and proper name ... 294

A. g-nu do. do. ... 294

A. African "• ... 295

Antlion 163

Ants, white 444

Ape, Barbary 185

Apis Lat., a bee 446

Aplysia ... GV., a marine animal 218

Aptenodytes Gr., unable to fly, and diving- ... 317

Apteryx ... ... ... Gr., without wings ... ... ... 315

Arctomys ... ... Gr., bear- mouse ... ... ... 92

554 GLOSSARIAL INDEX.

PAGE

Arachnida Gr., a spider 455

Aranea Lot., a spider 456

Arenicola Lat., sand inhabiting 74

Argonauta Gr., Argonauta 511

Armadillo ..» ... Gr., little beast in armour 281

Arterial system 54

Articulata Lat, jointed ... 405

Ascaris Lat., round worm 217

Ascidia Gr., a leather bottle 219

Assimilation ••• ... 87

Aspic 349

Asterias Gr., a star 208

Astroides Gr., starlike 530

Attitudes 146

Auditory apparatus ... ... ... ... 114

Australian 262

Axolotl Mexican proper name ... 195,866

Baboon ... ... 267

Balaena Gr., a whale ... 301

Balaenoptera Gr., a firmed whale 28, 300

Balanus Gr., an acorn 492

Balm-cricket 450

Bashikouay ant ... ... ... ... 445

Bat, skeleton of , 154

„ large eared 276

Baya 172

Beaver ... 174

Bee 451

Beetles ... 23

Bethylus... ... ... Lat., an insect ... ... ... 215

Bile 41

Binny ... ... 395

Biphora Lat., twice bearing 524

Birds, class of 305

„ arterial system 331

Bison ^ ... 287

Bittern * 345

Blatta Lot., a cockroach 415

Blood 45

„ circulation of ... 50

Boar 31

Bombus 5.. Lat, a buzzfly 446

Bombylus Lat., a buzzfly 24

Bombyx... Gr., the silkworm ... ... 407,434

Bones 130

Bosjesman Dutch, man of the woods 261

Brain, human 97

„ of fishes and birds 106

„ of rorqual 107

,, of ostrich 323

GLOSSAEIAL INDEX. 555

PAGE

Breastbone of Birds 310

Bucardium Gr., the heart 521

Buffalo 291

Bug ". 417,451

Bull, Scotch 288

Butterfly 419

Caffre Arabic, " unbeliever" 264

Calmar 508

Camel 239

Carneleopard 297

Canis ... Lat., dog 272

Cantharis Gr., a beetle 439

Capillary vessels 57

Capricorn beetle 407

Carabus Lat., a beetle ... 415

Carinaria Lat., a keel ... 518

Carnassial tooth of lion ... 199

Carnivora Lot., flesh-eating ... 268

Caryophyllus Lat., a clove 225

Cassowary, galeated 306

New Holland 319

Cattle 256

Caucasian race _ ... ... 258

Centipede ... ... Lat. , many-footed 211

Cephalopoda ... ... Or.* head-footed ... ... ... 507

Cerebrum Lat., brain 97

Cervical vertebrae 309

Cetacea 299

Chalcis ... ... ... Gr., shining like brass ... ... 350

Chameleon ... ... ... ... ... 353

Cherokee 264

Chyle ... Gr., juice 41

Chyme Gr., juicy pulp 35

Chimpanzee ... ... ... ... ... 181

Circulation of the blood ... 50

Cirripeda Gr. hair-footed 490

Cloportes Lat., a woodlouse 467

Cockchafer 439

Classification, tables of 200,227,257,549

Cockroach 441

Cod 390

Coluber Lat., a viper 362

Conformation of animals 189

Conops Gr., conefaced ... , 411

Coptic race 260

Coral polyp 224

Courser, European 318

Cowry ... 219

Crab 468,480

Crane, pouched 325

556 GLOSSAEIAL INDEX.

PAGE

Crane, common 345

Crawfish, or lobster ... 194

Cricket ... 408,441

Crocodile Greek 361,364

Crotalus Gr., a "rattler" 357,363

Crustacea Lat.y crusted 465

Cucumber, sea 224

Curassow 342

Cuttlefish 212,223,513

Cyclops Gr., with one eye 204, 490

Daauw Hottentot proper name 283

Danais Gr., the Danaides 447

Dayfly 436

Deglutition 311

Dental apparatus 25

Dermestes ... .. Gr., skin eating 438

Desman 245

Diastole Gr., to stretch through 57

Digestion 18,20,36,420

Dinornis Gr., terrible bird 320

Diver 331

Divisions, primary, of animal kingdom ... 207

Dodo 344

Domesticated animals 255

Dormouse 279

Dragon Lat., draco 355

Dragon-fly 215,443

Duck, Eider 335

„ Carolina 335

„ China 336

„ Egyptian 336

Dugong 246

Dziggetai Tar tar proper name 284

Eagle 309

„ royal ^ ... 318

Ear 114

Earwig- 411

Echidna Gr., a mythological monster ... 207

Echinus... Lat., sea-urchin 526

Eft or newt 370

Eider-duck 335

Eland 295

„ striped 296

Elephant 23

„ of India 243

,, of Africa 245

„ proboscis and molars 244

Elk 242

Emeu of New Holland 319

GLOSSARIAL INDEX. 557

PAGE

Emeu, trachea of 334

Encephalon 101

Encrinites ... ... ... ... ... 527

Endosmosis Gr., internal impulsion 13

Eolis Gr., a sea-animal 518

Ephemera Gr., ephemeral 436

Ethiopian race 264

Excretion 90

Exhalation and the Secretions 80

Eye-globe dissected 119

„ orbit and attached muscles 125

Falcon, wing of 312

„ head of. 324

Fasciola Lat., a small band 501

Fin, dorsal 377

Fish, circulatory apparatus in 67

Flamingo ... ... ... ... ... 347

Flathead 395

Flea 451

Fluke-worm ... 501

Fo3tus of Greenland-whale 302

Follicles 83

Forficula Lat., an earwig 411

Fowl, common 329

Fox 273

Frigate-bird 313

Frog 365

„ metamorphoses of. 196,366

„ bloodvessels of tadpole ... 367

„ skeleton of 369

Fulmar petrel 324

Functions of animals ... 11

Gavial Hindu, gharrial, a crocodile 28

Ganglionic system ... Gr., a knot 102,104

Gecarcinus Gr., land-crab ... ... ... 484

Gecko 353

Genus and species 395

Giraffe 297

Globules of the blood 46

Glow-worm 422

Glycera Gr., sweet 498

Gnat, larva 435

Gnu Hottentot, " gnu" 294

Goatsucker 325

Goat, head of 242

„ Angora 292

Goldfinch ... 171

Gorilla GiveJc? Equat. African, rfguyla ... 182

Gourami 394

558 GLOSSAEIAL INDEX.

PAGB

Grasshopper ... 406

Grebe 331

Grosbeak, nest of ... . 174

Gull, black-headed ... 308

Halys 450

Hamster ... 166

Harmonies, organic 199

Haversian canal 27

Hearing, sense of 113

Heart 53

Hedgehog1 ... ... ... ... ... 277

Hemipterous insects ... Gr., half-winged 417

Hippa Gr., a crustacean 476

Hippopotamus Gr., river-horse 285

Hippocampus Gr., a field-horse 381

Holothuria Gr., sea-tail 224, 528

Homology ... ... ... ... ... 199

Hornbill, rhinoceros 327

Horse, skull of 137

Humble-bee 446

Humming-bird 339

Hyalaea Gr., glassy 222

Hyaena ... Gr., hyaena 271

Hydatina Gr., a hydatid 500

Hydra Gr., a mythological sea-monster ... 190

Hyrax Gr., a shrew 241

Ibis 316

„ head of • 317

Ichneumon fly ... ... ... ... ... 412

Ichthyosaurus Gr., fish-lizard 354

Infusoria Lat., in infusions 226,533

Insalivatipn 32

Insects, circulation in ... ... ... ... 69

„ class of 405

Intelligence and Instinct 159

Intestines ... ...-,, ... ... ... 42

Itch insect * 464

Julus Gr., woolly 215,454

Jerboa 280

Kangaroo ... ... ... ... ... 303

Kidneys 33

Kingdoms of Nature 2

Kingfisher 326

Kite 324

Klipdas ... 241

Lacteals 17

Laemmergeyer ... 337

GLOSSARIAL INDEX. 559

PAGE

Lamprey ... ... ... ... ... ... 394

Lampyris Gr., a glow-worm 422

Landcrab ... 216

Lark ... 339

Larynx, mechanism of 157,333

Leaf-insect ... ... ... ... ... 442

Leaping ... 150

Leech ... ... 217

Lemur ... ... ... Lat, a ghost ... ... ... ... 266

Lepidosiren ... ... Gr., scaly siren ... ... ... 195

Lernaea Gr., hydra 203

Lerot Fr., " a dormouse" 279

•Libellula Lat., a dragon-fly 443

Limnaea Gr., pool-living ... 212

Limnadia ... ... 489

Limulus Lat., mud 192,493

Lion, skull of 28

Liver - 40

Lizard ... 66, 348

Llama ... ... 290

Lobes of the brain ... ... ... ... 97

Lobster.... ... 68,211

Locomotion .... 466

Locust ... ... . 340

LoligO ... 24, 508

Louse ... ... .*. ... 453

Lungs, &c., in man 52

„ of a bird ... .... ... 332

Lungs and trachea 76

Lymphatics ... ... ... ... ... ... 16

Machaon butterfly ••• ... Gr., a mythological hero - 424

Mactra ... Lat., a kneading-trough 220

Maia ... ... ... £r., a mythological goddess 468,477

Malacopterurus Gr., smooth-tailed 386

Mammalia, theoretical figure of ... 208

classification of ... 233

„ senses ... .... ... ... ... ... ... 250

Man ^ ... 259

Mantis ... •. 409

Marmot 92

Marmoset 22

Mastication 33

Medusa Gr., one of the Gorgons 529

Memnon, young ... ... ... ... ... 260

Millipede Lat., thousand feet 215,455

Moa of New Zealand 321

Modes of existence 3

Mole 249

Mole-cricket 409

Mollusca ... Lat., soft-bodied ... ... 68,504

560 GLOSSAEIAL INDEX.

PAGE

Mongol race 259

Monodon Gr., one-toothed 30, 31

Morpha Gr., sleep 410,419

Motion 129,135

Moth, oak-leaf 448

Mouth and throat 34

Mouflon Sardinian, " muffione" 293

Movements 127

Mullet 372

Musk buffalo 292

Muscles 131

Mucous membrane 20

Muscular contraction 127

Myelon Or., marrow 103

Mygale ... Gr., a spider 167,456

Myrmecophaga Gr., ant-eater 31

Nasal fossae in man 112

Narwhal 30

Natural history, its objects and utility 1

Nautilus, paper ... ... Gr., nautilus ... ... ... ... 511

„ pearly... ... do. ... ... ... ... 512

Necrophora Gr., dead-eating 169

Negro, profile of 187

„ skull of 263

Nemestrina Gr. , a two-winged insect 418

Nepa ... Lat., a scorpion 451

„ respiratory apparatus in ... 75

Nereis Gr., a sea-nymph ... 217,497,498

Newt, or Eft 370

Notonectes ... ... Gr., back-swimming 408

Nuthatch 338

Nutritive and intussusceptive functions 3

Nutritive decomposition 87

Octopus Gr., eight-footed 508

Opossum 235

Optic lobes * 99

Organization 4

Orneodes ... 410

Ornithorynchus ... Gr., bird-beaked 304

„ figure 304

„ femoial gland , ... 305

Ostracion Gr., shelled 390

Ostrich, skeleton 209, 318

„ brain 323

Otter 272

Owl 338

Ox-fly 451

Oyster, anatomy 520

„ pearl . ... ... ... 521

GLOSSARIAL INDEX, 561

PAGE

Palaemon Gr., a mythological personage 475,482

Paludina Lat., marsh living ... 219

Pancreas Gr., all fleshy 40

Pangolin ... ... ... ... ... 238

Panther 369

Paradise bird 338

Parroquet 340

Paussus ... ... ... ... ... .., 407

Peacock butterfly ... ... ... ... 447

Pediculus Lat., a louse 453

Pelecanus ., 313

Pelican 326

Penguin 317

Pentatoma Gr., seven incisions 450

Perch 373

Pericardium Gr., around heart ... 53

Pharynx ... ... Gr., conveying ... ... ... 35

Phyllium Gr., a leaf 442

Pigeon 342

Pike 391

Plaice 392

Plesiosaurus ... ... Gr., near to lizard ... ... ... 355

Plethora 17

Pleurobranchus Gr., lung gilled 517

Plumatella Lat, feathered 523

Podophthalmus... ... Gr., eyed-feet ... ... ... 478

Podurella .,. ... Lat., little tail feet 410

Poison glands 358

Polydesmus Gr , many bundled 455

Polypi ... ... ... Gr., many feet ... ... ... 530

Porcupine ... ... ... ... ... 236

Porpoise ... 234

Poulpe 508

Prehension, organs of ... ... ... ... 153

Psora Gr., itch 464

Ptarmigan 341

Pterodactyle Gr., winged finder 356

Pteropoda ... ... Gr. , winged foot ... ... ... 519

Ptinus ... ... ... Gr., a boring1 insect ... ... ... 438

Pyralis Gr., a moth-like insect 449

Rabbit 25

Rattlesnake 357

Reindeer 296

Relation, functions of 94

Remora, or sucking-fish ... ... ... ... 379

Reptilia, class of ... ;>is

Respiration ... ... ... ... ... 69

,, apparatus of ... ... ... ... 16

Rhinoceros of India ... ... ... ... 210

of South Africa 241

o o

562 GLOSSAKIAL INDEX.

PA an

Rhizostoraa Gr., root mouth 224

Rodent, head of 278

Roebuck 248

Rorqual ... ... ... ... ... ... 28

„ giganteus ... ... ... ... 299

„ of Fabricius, head and tail 300

Salamander Lat.t a newt 370

Salivary gland ... ... ... ... ... 82

Salmon 388

Sapajou ... ... ... ... ... ... 156

Scarabaeus Lat., a beetle 458

Scolopendra Gr., a centipede 211

Scops Gr., an owl 338

Scoter duck 322

Seal 275

Secretions 81

Scorpion 460

Serpula Lat., to creep 499

Sensation 107

Sepia Lat., a cuttle-fish 223,513

Shark 380,393

Shrew mouse ... ... ... ... ... 277

Shrimp 483

Sirex 446

Sitta Gr., a nuthatch 338

Sight, sense of 118

Silkworms 427

Skate 393

Skeleton of man 140

„ camel 141

Skin 109

Skull of man 136

Smell, sense of 112

Snail, anatomy of ... ... ... ... 213

Snake 326

Spanish fly 439

Sparrow * 326

Sparrowkawk, wingof ... ... ... ... 314

Sperm whale 299

Spider 216

Spinal marrow ... ... ... ... ... 103

Spongariffi Sponge-like 534

Sponge 225

Sphinx Gr., a monster 403,448

Squilla - ... Lat. a prawn 483

Squirrel 165

Stag 293

Standing 147

Stylops Gr., column-eyed 453

Sturgeon... ... ... ... ... ... 393

GLOSSABIAL INDEX. 563

PAGE

Stomach 35,37,39,252

Sucking-fish 379

Su an, breast-bone of 310

Swimming- and Flying 151

Sylvia Lat,, a warbler 172

Systole Gr., I contract 57

Taenia Gr., ariband 503

Tailor-bird, nest of 172

Talitrus Lat., a sandhopper 214

Tapeworm 503

Tapir Brazil, proper name 245

Taste, sense of Ill

Tasmanian, skull of 263

Teeth, the 25

„ human, carnivorous and insectivorous 29

„ herbivora and frugivora ... ... ... ... ... 30

Tellina ... Gr., a muscle 520

Terebratula Lat., I bore 521

Termites Lat., the branch of a tree 444

Tern, or sea-swallow ... 341

Testudo Lat., a tortoise 349,351

Theridion Gr., a spider 463

Thoracic canal ... 15

Thorax of man 77,143

Throat and mouth ... ... ... ... 34

Toad 365

Torpedo 384

Tongue, structure of Ill

Tortoise, land ... ' 349,351

Tortrix Lat., I wreath 167

Touch 109

Trumpeter 346

Tsetse fly 452

Tunicata Lat., a tunic 522

Tunny . 391

Turkey, merrythought of 310

Turtle 351

heart of 360,380

Tympanum of the ear ... £aZ.,adrum 115

Urinary secretion 85

„ apparatus 86

Venous system ... ... ... ... ... 55

Veretilli 532

Vertebra 139

„ ideal 198

„ number of, in cetacea ... ... ... ... ... 302

Vertebral column 139

Vision, mechanism of ... ... ... ... 120

564 GLOSSAEIAL INDEX.

PAGE

Voice 156

Vole, field 278

Vulture, griffon 325

„ skeleton of 155

Walking 148

Wasp's nest 176

Weasel 271

Whale, head of 27

„ sperm 299

„ foetus of. 302

Whalebone 301

Wimble 438

Wing of the falcon 312

„ of the sparrowhawk 314

Woodpecker, pied 314,328

Wren 339

Xiphias Gr., a sword 376

Xylocopa Gr. , woodworking ... 170

Yak,male 291

Zebra 282

Zoological classifications 200,549

Zoophytes Gr., animal plants 529

h

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