CORNELL
UNIVERSITY
LIBRARY

 

FROM

H.F.Roberts

 
THE

DOCTRINE OF DESCENT

AND DARWINISM

BY
OSCAR SCHMIDT

PROFESSOR IN THE UNIVERSITY OF STRASBURG

WITH TWENT\-SIX WOODCUTS

NEW YORK
D. APPLETON AND COMPANY

1900
Aegon]

Authorized Edition.
PREFACE.

THE important chapter which closes this work was
included in a public lecture which I delivered at the
meeting of Naturalists and Physicians held this year at
Wiesbaden; my purpose being, as I am willing to con-
fess, to ascertain, by experience, whether on this signifi-
cant subject I had struck the right note to suit a circle
of hearers and readers not hampered by prejudice.

After the reception given to this fragment, which I
also issued in a separate pamphlet, under the title of
“The Doctrine of Descent, in its application to Man”
(Die Anwendung der Descendenzlehre auf den Mens-
chen), I venture to hope that the whole may find a
welcome.

With the exception of the Ecclesiastico-political ques-
tion, no sphere of thought agitates the educated classes
of our day so profoundly as the doctrine of descent.
On both subjects the cry is, “ Avow your colours!” We
have, therefore, endeavoured to define our standpoint

vv
vi PREFACE.

sharply in the introduction, and to preserve it rigidly
throughout the work. This is, indeed, a case in which,
as Theodor Fechner has recently said, a definite deci-
sion has to be made between two fundamental alter-
natives. May our exposition afford a lucid testimony
to this dictum of one of the patriarchs of the philo-
sophical view of nature.
Oscar SCHMIDT.
StrassBurG, October 18th, 1873.
CONTENTS.

I.

INTRODUCTION—-SUMMARY OF THE RESULTS OF LINGUISTIC IN-
QUIRY—POSITIVE KNOWLEDGE PRELIMINARY TO THE Doc-
TRINE OF DESCENT—BELIEF IN MIRACLE—THE LIMITS OF
THE INVESTIGATION OF NATURE . ‘ ‘ 3 - -

II.

THE ANIMAL WORLD IN ITS PRESENT STATE . 4 ‘

III.

THE PHENOMENA OF REPRODUCTION IN THE ANIMAL WORLD .

Iv.

Tue ANIMAL WORLD IN ITS HISTORICAL AND PALAONTOLOG-
ICAL DEVELOPMENT. < i ‘ * 4

Vv.

THE STANDPOINT OF THE MIRACULOUS, AND THE INVESTIGATION
oF NATURE—CREATION OR NATURAL DEVELOPMENT—LIN-
N&US—CUVIER—AGASSIZ—EXAMINATION OF THE IDEA OF
SPECIES . . ‘ 7 r ” “ ‘ . a ‘

VI.

NATURAL PHILOSOPHY—GOETHE—PREDESTINED TRANSFORMA~

TION ACCORDING TO RICHARD OWEN—LAMARCK A ‘
vu

PAGE

24

39

60

82

104
viii CONTENTS.

VIL

LYELL AND MoDERN GEOLOGY—DARWIN’s THEORY OF SELEC-

TION—BEGINNING OF LIFE . 5 i % , ‘
VIII.

HEREDITY— REVERSION—VARIABILITY —~ADAPTATION — RESULTS
oF UsE AND DIsusE OF ORGANS—DIFFERENTIATION LEAD-
ING TO PERFECTION 5 “ ‘ 7 g : ‘ é

IX.

THE DEVELOPMENT OF THE INDIVIDUAL (ONTOGENESIS) IS A
REPETITION OF THE HISTORICAL DEVELOPMENT OF THE

FAMILY (PHYLOGENESIS) . : “og 7 P 5 7

X.

THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS IN THE LIGHT
OF THE DOCTRINE OF DERIVATION : ‘ 7 : zi

XI.

THE PEDIGREE OF VERTEBRATE ANIMALS . ‘. 2 s 5

XII.

MAN ei ‘ 7 ‘ i P : ‘ i

REFERENCES AND QUOTATIONS . : 2 7 : : i

PAGE

127

165

195

222

248

252

311
LIST OF ILLUSTRATIONS.

FIG, PAGE
1. Legs of Bird and Chick . . 5 : A 7 : : 9
2. Medusa, Tiaropsis Diadema . 5 i . "i - 31
3. Stauridium. Medusa, Cladonema Radiata ‘ ‘ , 43
4. Spermatozoa 3 r i ‘ * 45
5. Section of Larva of Ciieaeaes Seatige ‘ é , 7 » 51
6. Embryo of Hydrophilus Piceus 5 - . é . a 1153
7. Sessile Stage of Crinoid . ‘ ‘ P ‘ ; 7 » 56
8. Larva of Crayfish . é : : A ‘ ‘ - 56
g. Graptolites. ‘i z ‘i : s 3 5 ‘ 69
10. Trilobites remipes  . ; 3 5 r i ‘ : + 70
11. Palzoniscus ‘ é ‘ * . - ‘5 , o 72
12. Larva of Bewinodern : : . ‘ 7 é : - 197
13. Larva of Sea-Snail . ji 3 5 é 5 ; ‘ . 2C0
14. Stauridium. Cladonema . : - 5 i ‘ 5 - 203
15. Hydractinea carnea . e : : ‘ F 5 5 204
16. Larva of Parasitic Crustacea . 3 5 3 ; 7 . 207
17. Axolotl . ‘ : . . 5 : - : . 208
18. Amblystoma : : ‘ - - e » 209

1g. Ammonites Humphresianus . 7 <j : : . 214

20. Ancyloceras P : : ; » 216

21. Section of Larva of Celesnedus eae , : ; . 217

22, Larva of Lancelet . : : : : : : : » 251

23. Larva of Ascidian . : ‘ ‘ é : , ‘ + 253

24. Full-grown Ascidian . . e ‘ : - 255

25. Impression of Tail of Avchaeptene : : - 266

26. Skeletons of Feet: Anchitherium, Hispadans Haws A + 274

ix
THE DOCTRINE OF DESCENT
AND DARWINISM.

I.

Introduction—Summary of the Results of Linguistic Inquiry—Positive
Knowledge preliminary to the Doctrine of Descent—Belief in
Miracle—The Limits of the Investigation of Nature.

A CRAVING to understand existence pervades man-
kind, and the life of every self-conscious individual.
Every system of philosophy has endeavoured to penetrate
into the nature of things, and has originated in the at-
tempt to apprehend the coherency of those great series
of material and spiritual phenomena, of which man flat-
ters himself that he is the centre or the end.

Some quiet themselves by emphasizing the contrast
between mind and body, idea and phenomenon; others,
by the catchword of identity; some have deemed them-
selves and the world in the most beautiful harmony;
others, from the times of the Buddhists, in the 6th cen-
tury B.c., to the eccentric saints of the present day, the
followers and reformers of Schopenhauer’s system, re-
gard the world as a mere accumulation of discomfort

and conflict, from which the sage may escape by a com-
I
2 THE DOCTRINE OF DESCENT.

plete withdrawal into himself, and a return, by the force
of an iron will, to an absence of needs and to nothing-
ness.

In all these endeavours to be reconciled and contented
with the world, the consciousness of man has made no
very important progress. Marvellous as are the attain-
ments of our generation, whether in the domain of in-
dividual sciences, or in the sphere of commerce and
industry, it is scarcely less wonderful how little certain
or advanced is the opinion of the multitude on general
questions. Even now, as muchas in the days of
Aristophanes, the multitude, and likewise many men
of “culture,” allow themselves to be imposed upon by
empty jargon. We no longer burn witches, but verdicts
of heresy still abound. As the basis of scientific medi-
cine, our experimental physiology enjoys unexampled
encouragement, and a general instinctive recognition un-
paralleled in former times; but these do not prevent the
door from remaining open, in all classes of society, to
the most audacious quackery.

We have only to look round at the spiritualists and
summoners of souls, who now form special sects and
societies; at the advocates of cures by sympathy and
incantation, and we can but marvel at the extensive
sway of a superstition hardly superior to the Fetichism
of a race so alien to ourselves as are the negroes.
These are only individual cases of the very widespread
lack of judgment, which prevails wherever the supposed
enigma of human existence is concerned. Millions and
millions who would turn away indignantly if required to
believe that anything not entirely natural occurred in the
most complicated machine, in the most elaborate product
RESULTS OF LINGUISTIC RESEARCH. 3

of the chemical retort, or in the strangest results of phys-
ical experiment, are yet disposed to seek a dualism
behind the processes of life. Wherever, also, the ex-
planation of life, and the reduction of vital phenomena
to their true natural causes is concerned, they would
wish to deny point-blank the possibility of such explana-
tion or such knowledge, and to refer life to an unap-
proachable and mystic domain. Or, if the solution of
the problem of life be admitted in the abstract, at least
something peculiar, and a different standard from that by
which other living beings may be measured, is required
for the beloved Self.

If we thus see, on the one side, a great portion of our
contemporaries either standing before the most impor-
tant of all problems in utter perplexity and helpless-
ness, or solving it by the theology of revelation, we may,
fortunately, point, on the other side, to the goodly host
of those who, since the development of science has ad-
mitted of it, have encountered the investigation of man’s
place in nature with sincere interest, and have weighed
the problem with intelligence.

This craving for a knowledge based on philosophical
and natural science, became apparent about a century
ago, and coincided with the first beginnings of linguistic
science. It is the more appropriate to allude here to
this, as the theories of the origin of language are pro-
foundly affected and influenced by opinions as to the
origin of Man, and vice versa.

The result of an inquiry, made in 1580, as to the lan-
guage of Paradise, having been that God spoke Danish,
Adam Swedish, and the serpent French, Leibnitz,
in his letters to Newton, first attempted to regulate the
4 THE DOCTRINE OF DESCENT.

method of linguistic research by recommending as its
basis the study of the more recent and known lan-
guages. And when, in the middle of last century, the
two opinions, that language was invented or revealed,
were sharply opposed to each other, and when Siissmilch
(1764), in contradiction to Maupertuis and Jean J.
Rousseau, had established that invention was not possi-
ble without thought, nor thought without language, and,
therefore, that the invention of language was a self-con-
tradiction, Herder opportunely entered the lists with his
work on language (1770), which formed an epoch in the
science.

According to him, language begins with imitations
of sounds, at first almost unconscious; the tokens, as
he expresses it, by which the soul distinctly recalls an
idea. He makes language develop itself from the
crudest beginnings, by the increasing need of such
verbal tokens; and shows that with the development
of mankind, the store of words must also have uncon-
sciously and ‘instinctively increased. The multiplicity
of languages is due to the dispersion of nations, whose
idiosyncrasies are reflected in the various languages.
Thus Herder long ago pointed out the importance of
a psychology of nations. He was joined by Wilhelm
von Humboldt, whose opinions form the basis of the
present science of language, and who held that the imi-
tations of sounds are instinctively crystallized into words,
and that with this formation of words and language,
thought commences. It follows from the nature of these
beginnings, that language is the natural expression of
the spirit of a people; that it does not stand still, but
is for ever in process of transformation.
WHAT IS AFFINITY? 5

The science of language, with its great results, dis-
plays the most important side of human nature—man
in the elevation which he has gradually acquired above
the rest of the living world—but it displays this side
alone. Although the founders of linguistic inquiry, of
whom we have already spoken, had already represented
man as first acquiring reason and becoming man, by
means of language proceeding from primitive rudiments,
they were, nevertheless, satisfied to assume the privi-
leged position of man as an absolute endowment, or a
self-evident axiom. This continued as long as natural
' science was limited to a merely superficial classification
of organisms.

Man, as consisting of flesh and blood, seemed, in-
deed, akin to the higher animals; but so long as their
descent, their actual consanguinity was not discussed, so
long as nothing was demanded beyond their juxtaposi-
tion, according to the analogy of their characteristics,
without any scrutiny of the deeper causes of their diver-
gence or similarity, man indisputably occupied the highest
grade in the system of living beings. Linnzeus places
man in the order of Primates, together with bats, le-
murs, and apes, without, on that account, being accused
from pulpit and from chair of an assault on the dignity
of mankind. Buffon, likewise, was able, unrebuked, to
indulge his whim, by specially discussing our race in his
description of the ass.

Only when, quite recently, the world became aware
that the word “affinity,” hitherto uttered with supreme
indifference, was henceforth to be taken seriously and
literally, since that which is akin is also the fruit of one
and the same tree, a beam of joyful recognition thrilled
6 THE DOCTRINE OF DESCENT.

through those to whom man appeared a being com-
pletely within the bounds of nature. But others, who
can think of man only as a being absolutely endowed
above his natural surroundings, could not fail to regard
as a sort of crime the deduction which an all-embrac-
ing theory applied with relentless logic to man.

The interest with which the modern theory of kindred
and descent has been received does not, therefore, pro-
ceed from friends alone, but quite as much from antag-
onists, who perceive, more or less distinctly, the danger
with which the new doctrine threatens their standpoint
of miracle.

Even in England the opposition to the great Eng-
lishman, with whose name the revolution is connected,
has been very considerable, especially since it became
evident that, true to himself, he includes man also within
the range of his researches, and purposes to apply to
him all the consequences of his doctrine. But it appears
to me that the dispute and the agitation are still keener
on this side of the channel, where Darwinism is meat
and drink to the daily papers, and to the philosophical
and theological periodicals.

This phenomenon is obvious to all eyes, and we
are convinced of the deep importance of the subject
which, whether we take part for, or against it, must
influence our whole theory of life. Here too that has
happened to many, which so often happens in ques-
tions the difficulties of which are veiled by an apparent
general familiarity. Every one thinks himself capable
of deciding about life, and, since to non-scientific per-
sons the notorious relationship with apes is the alpha
and omega of the doctrine of Descent—since the most
REFERENCE TO DARWIN. 7

confused heads are often most thoroughly convinced of
their own pre-eminence—on no subject do we so fre-
quently hear superficial opinions, mostly condemnatory,
and all evincing the grossest ignorance.

I wish then to render the reader able to survey
the whole ramified and complicated problem of the
doctrine of Descent, and its foundation by Darwin, and
to enable him to understand its cardinal points. But
we must first dispose of a preliminary question of uni-
versal importance and special significance, which is fre-
quently ignored by philosophical and theological oppo-
nents, that is, the question of the limits of the investiga-
tion of nature. For if it were an established principle
that the mystery of the living is different from that of
the non-living, that the former might be disclosed, but
that the latter is shrouded in a veil which never can be
raised, as is even now so frequently asserted, then, in-
deed, all research directed towards the comprehension of,
life would be utterly vain and hopeless. ;

But if the possibility of investigating life and its ori-
gin be not opposed by any a priori scruples, still more, if
the limits of investigation and knowledge, which un-
doubtedly exist, are no other for animate nature than
for the inanimate world of matter, we may venture to
approach our task. This will be most adequately ef-
fected by making ourselves somewhat familiar with the
object of the doctrine of Descent, restricting ourselves,
however, to the animal world. If I say then that we must
obtain a foundation for the theory of derivation or de-
scent, for the doctrine of the gradual and direct develop-
ment of the higher and now-existing organisms from

lower ancestral forms—in short, for the doctrine of the
2
8 THE DOCTRINE OF DESCENT.

continuity of life, we must begin with a survey of the
animal forms now spread over the earth. As astronomy
begins with the mere classification of the stars and con-
stellations, and the knowledge of their apparent motions,
so do we also range our material in large groups, and
this in the manner offered by the historical development
of science.

What first strikes the observer of the animal world
is, that it consists of apparently innumerable forms. The
primary requirement is discrimination and arrangement.
In the first stages of their development, zoology, as well
as botany and mineralogy, necessarily consisted of mere
descriptions, of a knowledge of objects in a state of com-
pleteness. Physics and chemistry, on the other. hand,
deal with the investigation of phenomena directly refer-
ring to their origin, that is to say, with series of phe-
nomena mutually connected as causes and effects, the
knowledge of which, therefore, leads at once to results
satisfactory and tranquillizing to the mind. This de-
scription, at first limited to the exterior, was gradually
extended to the interior, because zootomy and compara-
tive anatomy, even more than fifty years ago, had ad-
vanced so far in the accumulation of endless details that
Cuvier then ventured to found the Natural System.

But this delineation of the animal world required
completion on two sides, and, as the science proceeded
towards perfection, it received it almost simultaneously
on both. To the knowledge of the existence of an
animal belongs also the description of its origin. I say
emphatically, “the description,” for the history of animal
development is not as yet in itself a natural science in
the same sense as the mathematico-physical sciences; it
COMPARATIVE ANATOMY AND EVOLUTION. 9

is a mere description of nature. But it yields a far more
accurate knowledge. In many cases it discloses, for the
first time, the significance of organs, and gives to com-
parative anatomy the confirmation, and frequently the pos-

sibility of interpretation. The
wing of a bird, in its individ-
ual parts,may be traced back
without difficulty to the an-
terior extremities of a rep-
tile or a mammal. But the
leg of a bird, as a complete
organ does not harmonize
with the leg of other verte-
brata until the development
of the bird in the egg reveals
that the disposition of the
segments and of the articula-
tions is precisely the same
in both cases, and that the
apparent anomaly is pro-
duced merely by the subse-
quent anchylosis of bones,
which generally remain sep-
arate.

The complete leg of the
bird (A) shows us at a, the
femur, or thigh bone, and
at 6, the tibia, or lower leg
bone; but instead of the

 

B

 

 

FIG. I.

bones of the tarsus and metatarsus, the latter of which
affords attachment to the toes, we find only the long bone
c, and at its lower extremity a small bone supporting the
1o THE DOCTRINE OF DESCENT.

four toes. Earlier writers were content to say that the
astragalus (c) replaces the tarsus and metatarsus. But
this is not the case; for the chick in the egg (B) shows
that the bird’s leg consists of the thigh, or femur (a), and
the shank or tibia (b), two tarsal (m, ), and three or four
metatarsal bones (c), and the toes, or phalanges; that
the upper tarsal bone is anchylosed with the tibia, and
the lower one with the consolidated metatarsus. Only
thus do we obtain a true perception of the fact manifested
in A, although the cause of the fact does not as yet ap-
pear.

The next example is rather more difficult. With-
out the history of development, comparative anatomy is
incapable of explaining why man possesses three little
bones in the auditory apparatus, the bird only one. The
history of development shows that out of the material
which in man ‘is applied to the formation of the malleus
and incus, two other portions of the skull are evolved in
the bird, having little or nothing to do with the auditory
mechanism. In short, the history of development, which
describes the gradual formation of the organism, is at
every step a beacon to comparative anatomy. In itself,
however, the history of development does not as yet
exceed the rank of a merely descriptive branch of erudi-
tion.

But if we now perceive how the evolutionary stages
of individuals represent series from the lower to the
higher, analogous to the various members existing side
by side in the same group of animals,—how, for instance,
the mammal passes through stages at which the lower
vertebrata remain fixed—a connection, at first sight
mysterious, is indicated between the evolution of the
POSITION OF PALHZONTOLOGY. Il

individual and the general constitution of the animal
world. This connection requires a scientific solution, a
reduction to causes, and this all the more urgently be-
cause their relations, though as yet hidden, are rendered
more probable by a third series of phenomena, the
conquest of which is likewise the achievement of natural
history. We allude to the record of the primeval
world.

Therefore, the knowledge of paleontological facts also
forms part of the indispensable basis of our operations.
Geology entered the right track forty years ago. We
now know that the world was not made backwards, but
originated by gradual formations and metamorphoses;
we may—nay, we must, infer that, at a definite epoch of
refrigeration, life appeared in a natural manner, that is
to say, without any incomprehensible act of creation; and
during this slow transformation of the earth’s crust, we
see living beings also gradually increasing, differentiat-
ing, and perfecting themselves.

Yet more. As was first convincingly proved in detail.
by Agassiz, one of the most vehement antagonists of the
theory of descent, we behold the palzontological or his-
torical series of organisms in the same sequence as the
phases of the development of the individual. There are
here vast chasms yet to be filled up by future observa-

» tion, though in many points we must not altogether

despair of success. But that the process of palzeonto-
logical development is, in general, the one indicated, is
disputed only by naturalists, who, like Barrande, years
ago anchored themselves to inalterable convictions in
science, as in creed, to dogmas.

These groups of facts, thus mutually referring to each
12 THE DOCTRINE OF DESCENT.

other, must be, in some degree, examined by any one
desirous of understanding them. In other words, we
must first review this vast material, before we turn our
attention to the magic spell which sifts and makes it
comprehensible. The toil is great, but the reward is
glorious! For, as regards the organic world, the craving
inherent in the human mind for the knowledge of reasons
—the need of causality, is satisfied singly and solely by
the doctrine of Descent. As yet we do not regard it as
complete; in many special cases it still owes us an an-
swer; but, on the whole, it does as much as any other
ingenious theory has done; it interprets by a single prin-
ciple those great phenomena which without its aid remain
a mass of unintelligible miracles. In a word, it raises
the knowledge of organic nature to a science. Even now
much of mere professional knowledge is wont to style
itself science. But as the doctrine of Descent includes
all life, it cannot stop on approaching Man. Were we
doubtful as to the origin of language, or even forced to
_admit total ignorance on this point, we could not, from
the existence of language, deduce the inapplicability to
man of the doctrine of Descent, without, as it seems to
us, arbitrarily breaking the chain of ratiocination.

We will now return to the preliminary question al-
ready indicated, as to the limits of the investigation of
nature. It is the more important, as incompetent judges
are wont to assert, that these limits are exceeded. The
frivolity of the logic by which such accusations are ren-
dered plausible to the multitude surpasses all licence.
We open, for instance, Luthardt’s ‘ Apologetic Lectures
on the Fundamental Truths of Christianity,” (‘* Apolo-
getische Vortrage titber die Grundwahrheiten des Chris-
THE INVESTIGATION OF NATURE AND MIRACLE. 13

tenthums,”) and see how he defends the reality of mira-
cles. ‘‘ Miracles,” he says, ‘‘ are not even miracles. They
do not even repeal the laws of nature; they merely re-
lease single occurrences from the dominion of those laws,
and place them under the law of a higher will and a
higher power. Of this we have many analogies in lower
spheres. If my arm hurls a stone into the air, this is
contrary to the nature of the stone, and is not an effect
of the law of gravitation, but the interposition of a
higher power and a higher will, producing effects
which are not the effects of the inferior powers. These
powers and these laws are not hereby repealed, but still
subsist.”

Let us pause a moment. To say that it is contrary
to the nature of the stone that gravity should be appar-
ently overpowered for a few moments by muscular agen-
cy, is physically absurd. The stone remains the same
weight, its nature is wholly the same, even while in
the motion of projection; and it is utterly unjustifia-
ble and sophistical to prate about muscular force as a
higher power opposed to gravity. If the stone
weighs two hundredweight, where is the higher power
then?

But when the champion of supernaturalism has mis-
led and prepared his hearers by his worthless analogy,
he proceeds: “Thus in the miracle, a higher causality
interposes, and evokes an effect which is not the effect
of the concatenation of those lower causalities, and yet
subsequently submits to these concatenations. But this
higher causality ultimately coincides with the highest
moral objects of existence. To serve them is nature’s
highest and most glorious pursuit. Therefore if miracle
14 THE DOCTRINE OF DESCENT.

stands in connection with these objects, if its conditions
are moral and not arbitrary, it is not contrary to nature
and its purpose, but in the highest sense conformable
© to it.” |

Thus as soon as belief in miracle comes into conflict
with the investigation of nature, it says: “ You overstep
your limits, and must here suspend your judgment. It
is a question of a higher moral object; the domain
of ethics is higher than that of physics, and therefore
a higher causality, which physicists have no right to
criticise, has suspended the chain of cause and effect
with which you naturalists are familiar.” This passage,’
in which one. of the most learned and honoured
champions of the belief in miracle lays down, like a
sophist, the limits of the investigation of nature, is, how-
ever, among the most moderate of its kind. But our
point of view and our logic differ radically from that
of antagonists of this description, in one particular,
namely, that to us the opposite to knowledge is igno-
rance, whereas they supplement knowledge by a so-
called higher knowledge, and by faith.

While holding by the maxim of Pico della Mirandola,
“Philosophy seeks, Theology finds, Religion possesses
the Truth,” ? it is forgotten that there are truths and
truths. The subjective visions and sensations of sound
by which the mentally diseased are excited and alarmed,
are to them a reality, yet a reality quite different to that
of the sights and sounds received through the healthy
organs of the senses. Philosophy and science seek that
truth which is deduced from the palpable connection
of things. But the other truths, so often negatived by
the former, are generally impalpable, and are incom-
LIMITS OF INVESTIGATION. .

mensurable with scientific truths. We will therefore abide
by the words of Goethe:

Whoso has art and science found,
Religion, too, has he ;

Who has nor art nor science found,
His should religion be.*

And now, having provisionally averted uncalled-for
objections and conflicts with ambiguous ideas, we may
quietly consider the limits of natural science. Let us
first pause at the address delivered with general approval
by the physiologist Dubois-Reymond, at the fiftieth
assembly of German Naturalists and Physicians. He
made reference to a passage in the classical works of
Laplace, in the Introduction to the Theory of Science,
which we cannot refrain from quoting in full. The
author of the ‘‘ Mechanism of the Heavens,” says: “ Pres-
ent events are connected with the events of the past by
a link resting on the obvious principle that a thing cannot
begin to exist without a cause which produces it. This
maxim, known by the name of the Principle of Sufficient
Cause, extends likewise to events with which it is not
supposed to come in contact. Even the freest will can-
not evoke them without a determining impulse.” “ We
must, therefore, regard the present condition of the uni-
verse as the consequence of its former, and the cause
of its future, condition. A mind, for a given moment
acquainted with all the forces which animate Nature,
and the reciprocal relations of the entities of which it is

* Wer Wissenschafft und Kunst besitzt,
Hat auch Religion ;
Wer jene leiden nicht besitzt,
Der habe Religion.
16 THE DOCTRINE OF DESCENT.

composed—possessed, moreover, of powers of compre-
hension sufficient to submit all these facts to analysis,
would be able to reduce to a single formula the motions
of the largest heavenly body and of the lightest atom.
To such a mind nothing would be uncertain, and the
future, like the past, would lie open before it. The
human mind in all the perfection which it has been able
to give to astronomy, offers but a faint image of such
a mind as this.” “All efforts of the human intellect in
the search for truth tend to approach the mind above
portrayed, but will always remain infinitely removed
from it.”

The Prussian physiologist then quotes the “ Thou
art like the Spirit whom thou comprehendest ” of Faust; *
and is of opinion that, in the abstract, the formula of
the universe is therefore not impenetrable to the human
intellect. But we own we are cordially indifferent to an
abstract perfection which never comes to light, and re-
gard the unattainableness of this vague formula of the
universe as a very endurable limit to human inquiry.
But independently of the dubious consolation of the
formula of the universe, we must agree with Dubois-
Reymond, when he considers that the limits, before which
the highest conceivable intelligence must pause, are a!so
insurmountable to man.

In accordance with the views now prevailing among
physicists and biologists, Dubois-Reymond has thus
specified the only limit given to the investigation of na-
ture: * “ The knowledge of natural science, more closely
defined above, is no real knowledge. In the attempt to
comprehend the constant, to which the mutations in

* Du gleichst dem Geist, den du begreifst.
ATOMS IDEALLY REPRESENTED. 17

the material world may be traced back, we stumble on
insoluble contradictions. An atom contemplated as a
minute, indivisible, inert mass, from which forces ema-
nate, is a chimera. In the impossibility of comprehend-
ing the nature of matter and force lies the only limit to
the knowledge of natural science.”

These propositions require some elucidation. Beyond
the subdivision mechanically possible, we must think of
substance or matter as consisting of particles ultimately
indivisible. Of these atoms, according to the present
standpoint of science, we are obliged to admit as many
different species as are not chemically reducible to more
simple elements. Now there is no doubt that these atoms
are, in the actual sense of the word, imaginary, hypothet-
ical quantities; and theory seems to indicate that all
matter, in the most different phenomena in the material
world, is based on a single species of atom.

Every manual of physics or physiology will show that,
in order to understand and calculate the properties
of these atoms and their combinations into the ingre-
dients of compound bodies, ‘susceptible of chemical
analysis, they are ideally represented under various
material forms, spherical, cubical, &c.; furthermore, that
in their combinations and co-operations as bodies, they
must be contemplated as surrounded by a rarefied
atmosphere of an universally diffused ether. But the
atom itself, and therefore the nature of matter, is
something incomprehensible, unattainable. In these
atoms, forces are inherent, which display themselves in
attractions and repulsions, and in motion in general.
But the final cause of these motions, and how far these
motions are, as it were, identical with the existence of
18 THE DOCTRINE OF DESCENT.

the atoms, is likewise included in the incomprehensibil-
ity of matter.

“If we pass over this,” says Dubois-Reymond again,
“the universe is approximately comprehensible. Even
the appearance on the earth of life in the abstract does
not render it incomprehensible. For life in the abstract,
contemplated from the standpoint of the theoretical in-
vestigation of nature, is merely the arrangement of mole-
cules in a state of more or less stable equilibrium, and
the introduction of an exchange of material, partly by
their own elastic force, partly by motion transferred from
without. It is a misapprehension to see anything super-
natural in this.”

This is the point which is usually contested with the
greatest vehemence. If all the motions and states of
quiescence of the inanimate world can be thoroughly
explained, the inexplicable must commence with the basis
of life. The imputation cast upon the reasoning powers
by this assumption may be formularized as follows, in
the question put by another sound and thoughtful physi-
ologist, A. Fick:* “ Are the characteristics of such a
particle, as already explained, applicable and effective
during the period of its sojourn in an organism? Thus,
for instance, will the motions of a particle of oxygen be
affected and altered by a neighbouring particle of hy-
drogen, in accordance with the same laws, when one or
both form part of an organism, as when they are out
of it?”

To reply in the negative is to avow the vitalistic
conception of life, that is, to take refuge in unknown
forces quite extraneous to matter, and to admit that the
self-same particle can vary its nature, according to

a
HEAT, A MODE OF MOTION. Ig

whether it be internal or external to an organism, is,
in other words, to affirm a miracle. If this is weighed
against the physical view, “ which in its perfection re-
duces every organic process to a problem of pure me-
chanics,” it may be done in the certainly impartial words
of the naturalist just quoted: “I am of opinion that the
mechanical view of organic life is demonstrated only
when all the motions in an organism are shown to be
the effects of forces, which at other times also are inher-
ent in the atoms. But similarly I should regard the
vitalistic view as proved, if in any case a particular mo-
tion actually observed to take place in an organism were
shown to be mechanically impossible. At present, neither
is to be thought of. Nevertheless, if a decision must be
made without full proof, I provisionally profess myself
unequivocally in favour of the mechanical view. Not
only does it recommend itself a priort by its superior
probability and simplicity, but the progress of scientific
development raises it almost to a certainty. When it is
seen how certain phenomena—such as the evolution of
animal heat, which it was formerly believed could be
explained only by vital force—are now ascribed, even by
those who in general assume the existence of a special
vital force, to the universally active forces of the material
particles, we find ourselves almost forced to the convic-
tion that by degrees all the phenomena of life will become
susceptible of ‘mechanical explanation.”

For the elucidation of the example just given of ani-
mal heat, let us observe that modern physics have learnt
to know heat as a peculiar mode of motion. The motion
of the hammer as it falls upon the anvil is not lost, but
is transformed into the atomic motion of the places struck,
20 THE DOCTRINE OF DESCENT.

a motion, invisible, it is true, but sensible as heat. But
likewise the combination of the particle of oxygen intro-
duced into the animal body by the respiration, with the
un-oxygenated constituents of the blood, is a motion sub-
ject to computation, and manifesting itself as oxydation,
combustion, or the evolution of animal heat. This chem-
ical act of combustion keeps the animal steam-engine
in motion.

In this way, by the application of mechanical princi-
ples, modern physiology has traced to their causes a
great number of organic processes, and the phantom of
vital force, which formerly reigned paramount over the
whole intestinal canal, incited the glandular cells‘and the
muscular fibres to their offices, and glided along the
nerves, now scarcely knows where to breed disturbance.

Thus the investigation of nature does not shrink from
enrolling life and the processes of life in the world of the
comprehensible. We are foiled only at the conception of
matter and force. But we are much further advanced
than Schopenhauer and his adherents, who for the idea of
Force substitute that of Will; for we have analyzed into
their several self-conditioned momenta a multitude of
processes, which the word “ Will,” incomprehensible in
itself, is supposed to explain in their totality; and much
further also than the fashionable philosopher of the day,
von Hartman, who regales us with the agency of the
“unknown” in the domain of the organic world.

“ And yet,” Dubois-Reymond thus formulates another
limit, “a new incomprehensible appears in the shape of
consciousness even in its lowest form, the sensation of
desire and aversion. It is, once for all, incomprehensible
how, to a mass of molecules of nitrogen, oxygen, hydro-
CONSCIOUSNESS. 21

gen, carbon, phosphorus, and so on, it can be otherwise
than indifferent how they lie or move; here, therefore,
is the other limit to the knowledge of natural science.
Even the mind imagined by Laplace cannot go beyond
this, to say nothing of our own. Whether the two limits
to natural science are not, perchance, identical, it is, more-
aver, impossible to determine.”

In these last words the possibility is indicated that
consciousness may be an attribute of matter, or may
appertain to the nature of the atoms. And we may add,
that the attempt has of late been repeatedly made to gen-
eralize the sensory process, and to demonstrate it to be
the universal characteristic of matter, as by von Zollner,
in his work on the Nature of Comets, which has created
such a justifiable sensation. He holds that, if by means
of delicately-formed organs of sensation it were possible
to observe the molecular motions in a crystal mechan-
ically injured in any part, it could not be unconditionally
denied that the motions, hereby excited, take place ab-
solutely without any simultaneous excitement of sensa-
tion. We must either renounce the possibility of com-
prehending the phenomenon of sensation in the organ-
ism, or “hypothetically add to the universal attributes
of nature, one which would cause the simplest and
most elementary operations of nature to be combined,
in the same ratio, with a process of sensation.”

It might be imagined that reflections of this kind
would lead to the delusive abysses of speculation; but
if, still speaking only of organisms, we descend from
the manifestations elicited by sensations of desire and
aversion in the higher consciousness of man and of the
superior animals, till we see all reaction to external ex-
22 THE DOCTRINE OF DESCENT.

citation dwindle into the scarce perceptible motions of
the simplest protoplasmic animalcule, it is evident that
there can be no question here of either consciousness or
will. We cannot then separate the idea of those sensa-
tions of desire and aversion, by which motions are ex-
cited, from the elementary attributes of matter, as we are
wont to do with regard to the higher animals.’

In precisely the same sense, it was said some years
ago by one of the most talented investigators of lan-
guage—Lazarus Geiger, now unfortunately deceased: ”
“But how is it, if further down, below the world of
nerves, a sensation should exist which we are not capa-
ble of understanding? And it probably must be so.
For as a body that we feel could not exist unless it con-
sisted of atoms that we do not feel, and as we could not
see a motion were it not accompanied by waves of light
which we do not see, neither could a complex living being
experience a sensation strong enough for us to feel it
also, in consequence of the motion by which it is mani-
fested, if something similar, though far weaker and im-
perceptible to us, did not occur in the elements, that is
to say, in the atoms. If we only consider that we are as
little capable of knowing that the falling stone feels noth-
ing, as that it does feel; it is fully open to us to decide,
in accordance with the greatest probability, that the world
is susceptible of explanation.”

We have examined the limits which the investigation
of nature has prescribed for itself. The organic world,
far from rearing itself before us as an incomprehensible
entity, invites us to fathom its nature, and promises to
reflect fresh light upon the inanimate world.

We must now pass in review a great portion of ani-
MAN HAS RISEN FROM A LOWER GRADE. 23

mate nature, and shall then arrive at the same con-
clusion as the linguistic inquirer, to whom—we again
quote his words—“ it became, on historic grounds, incon-
trovertibly certain that man has risen from a lower, an
animal grade.”
24 THE DOCTRINE OF DESCENT.

II.
The Animal World in its Present State.

In order to approach the doctrine of Descent, and to
prepare for its necessity, we purpose next to pass in re-
view a main part of its object,—the present condition
of the animal world in its general outlines. Organisms,
as every one may see, are distinguished from animate
bodies by a certain mutability of existence; a sequence
and alternation of phenomena, combined with constant
absorption and expulsion of matter. These changes,
which are ultimately molecular motions, and are there-
fore calculable, definable, and susceptible of investiga-
tion, take place in particles in a state of saturation—that
is to say, soaked in water and aqueous fluids; and this
peculiar, yet purely mechanical condition, suffices for the
explanation and comprehension of many of the neces-
sary phenomena of life. Experience shows that this ca-
pacity for saturation, and this mobility, essentially char-
acterize the combinations of carbon; and the sum of these
motions and displacements, of which a great part has
already been susceptible of mathematically certain in-
vestigation, is termed Life.

Now it is impossible to resist the impression that there
are simple and composite, lower and higher, living beings;
and we likewise feel, more strongly than words will ex-
press, a certain antithesis between the plant and the ani-
LOWER FORMS OF LIFE. 25

mal. Poetically regarded, the plant is the passive organ-
ism as described by Ruckert:

“Tam the garden flower
And meekly bide the hour,
The guise, with which you come
Within my narrow room.” *

The antithesis of the passive, quiescent plant and the
pugnacious active animal diminishes, however, as we
descend in the scale of both kingdoms. The more
highly developed animal evinces its animal nature by
the vivacity with which it reacts to external influences
and excitations. In the lower animals the phenomena
of life assume a more vegetal character, and in many
groups of lower beings, which Haeckel has recently
comprised under the name Protista, we see the pro-
cesses of metamorphosis of tissue, nutrition, and repro-
duction taking place, indeed, but in a manner so simple
and undifferentiated, that we too must attribute to these
beings a neutral position betwixt plants and animals.
We gain the conviction that the roots of the vegetal
and animal kingdoms are not completely sundered, but,
to continue the simile, merge imperceptibly into each
other by means of a connective tissue. In this inter-
mediate kingdom, [ still believe that the “ primordial
slime” (Urschleim), or Bathybius, has a right to hold
a position. Many thousand cubic miles of the sea-
bottom consist of a slime or mud composed in part
of manifestly earthy inorganic portions, in part of

*“Tch bin die Blum im Garten
Und muss in Demuth warten,
Wann und auf welche Weise
Du trittst in meine Kreise.’
26 THE DOCTRINE OF DESCENT.

peculiarly formed calcareous corpuscles, still perhaps am-
biguous in their nature (the Coccoliths and Rhabdoliths),
and finally, which is the main point, of an albuminous
substance.

This slime, the so-called Bathybius, does not, how-
ever, exhibit individuality, or the definiteness of a sepa-
rate existence; it resembles the shapeless mineral sub-
stances, each particle of which bears the characteristics
of the whole.

The conception of an organism as a being compose
of various parts, with various offices or functions, and
appearing under a definite form gradually developed, ‘is
in our day so inherent and intuitive, that it is only with
great exertion that we are able to accommodate our-
selves to the idea of a living mass either absolutely
formless and undefined, or defined arbitrarily and acci-
dentally. Let any one, who either cannot or will not
do this, pause for a moment to contemplate another
simple being—for instance, Haeckel’s “ Protamoeba.”
A small albuminous mass increases by the absorption
of nutriment, and by the appropriation of matter, until
it reaches a certain circumference, and then propagates
itself by spontaneous fission into two equal parts. To
our means of observation, these and similar beings are
the simplest organisms devoid of organs. While ac-
centuating the limits of research as restricted by inade-
quate means of observation, we maintain the validity of
Rollet’s retort,’ that our reason cannot properly admit
such homogeneous organisms, performing all the func-
tions of life solely by means of their atomic constitu-
tion; that we are dealing with the still utterly unknown
structure of the molecules formed by the aggregation of
PROTISTA. 277.

atoms; and that if Briicke says, ‘“ Apart from the molecu-
lar structure, we must also ascribe to living cells another
structure of a different order of complexity, and this
is what we denote by organization,” we must likewise
ascribe this yet unknown combination to the Monera of
Haeckel.

But independently of this complexity of the molecular
structure, it is of extreme importance to the investiga-
tion of animate nature to have become acquainted with
bodies which present the simplest structure to the as-
sisted eye, and to anatomical research. The substance
which characterizes them is found again in plants as
well as in animals; and plants and animals must now
be regarded as two classes of organisms, in which the
processes of self-preservation and reproduction have, in
different ways, assumed the character of a higher com-
plexity and development, by the differentiation of the
originally homogeneous substance into various morpho-
logical structures and organs.

As we shall have another opportunity of expressing
an opinion in regard to the beginnings of animal life, and
its points of contact with protista and plants, we shall
transfer ourselves from the dubious boundary line into
the midst of the animal kingdom, in order to master our
subject by sifting and arranging it.

The first impression of infinite variety is succeeded by
another, that there are lower and higher animals. On
this point complete harmony prevails. For if, from teleo-
logical considerations, invalid in our eyes, the nature of
every creature were said to be perfect, that is, in corre-
spondence with its purpose or idea, every one takes it for
granted and self-evident that a standard of excellence
28 THE DOCTRINE OF DESCENT.

exists, without taking account of the scale by which it
rises or sinks. This standard will, however, soon be made
manifest by the comparison of a lower with a higher ani-
mal. Let us select the fresh-water polype and the bee.

The little animal, several lines in length, which in our
waters usually lives adhering to a plant, is a hollow
cylinder, of which the body-wall is formed of two layers
of cells. The external layer gives rise to fibres which
act as muscles, and to a supporting membrane which
may be compared to a skeleton. The mouth is sur-
rounded by arms of similar construction, and varying in
number from four to six. The surface of the body is
studded with numerous little stinging vesicles, which
by their contact stun any smaller animalcule straying
within the reach of the polype, and render them an
easy prey. This is, in a few words, the construction of
the animal. It possesses no arterial system, no special
respiratory apparatus; the functions of the nerves and
the sensory organs are performed by the individual parts
of the surface. Reproduction is usually effected by the
budding of gemmules, which fall off at maturity, but
occasionally also by the produce of very simple sexual
organs.

On the other hand, hours do not suffice to describe
the structure of a bee. Even externally, its body,
which possesses so highly complicated a structure, prom-
ises a rich development of the interior. The man-
ducatory apparatus. can be rendered comprehensible
only by comparison with the oral organs of the whole
insect world. The various divisions of the alimentary
canal are each provided with special glands. The rich
psychical life, all the actions which imply intelligence,
SYSTEMATIC ARRANGEMENT. 29

calculation, and perception of external situation, are
rendered possible by a highly developed nervous system,
and the marvellously complex sensory organs combined
with it, of which the eyes are especially remarkable.
Independently of the generative organs, consisting of
manifold parts of greater or less importance, the history
of the multiplication and development of the bee de-
mands a study of itself.

The function, and therewith the rank and value, of
the bee’s body seem to us higher than that of the polype
in proportion as it is more complex. The superior com-
plexity and variety of the parts is anatomically evident,
and similarly the higher phase of the life. The superior
energy of the existence, the functional capacity and per-
fection of the bee as contrasted with the feebleness of
the polype, is obviously a result, or more correctly an
expression, of the greater mechanical and physiological
division of labour. In one animal, as in the other, life
is spent in the function of self-preservation and the
maintenance of the species, or reproduction; in both,
the cycle of phenomena is limited, unbroken; but the
means of execution are very different, and therefore
the general effect is different. In the variety and
correlation of the organs destined for the different
manifestations of life, we have a standard for the rank
of the animals. This rank has a twofold character,
general and special. In other words, the position of
an animal in the system is defined, first, by the
general attributes, which it has in common with the
forms harmonizing with it in the main characters
of their organization; and, secondly, by the more:
special characteristics, which place the animal in its
30 THE DOCTRINE OF DESCENT.

own rank and station among its own immediate kin-
dred.

Some insight into this classification of the animal
kingdom is naturally indispensable to any one, who
wishes to test and understand its reasons, and to render
an account of it is an essential part of our task.

Since Cuvier’s reconstruction of Zoology in the early
part of this century, our science has been familiarized
with the expression “type,” or “ fundamental form,” in-
troduced, long before, by Buffon. Cuvier, by extensive
dissections and comparisons, first proved that animals
were not, as people were formerly inclined to suppose,
made on a last or shaped upon a block; but that they
fall into several great divisions, in each of which expres-
sion is given to a peculiar constitution, arrangement, and
distribution of the organs; in short, to a peculiar style.
The sum of these characteristic peculiarities, as well as
the whole of the species united in it, was termed a “ type.”
Various views, it is true, even now prevail as to the ex-
tent of several of these types or families, as we will already
term them; but if we disregard the dubious, and in many
ways suspicious, existences, generally comprised under
the name of primordial animals, there is a general agree-
ment as to the following number, but less as to the se-
quence of the animal types, than as to those groups, each
of which has its peculiar physiognomy and special char-
acteristic structure.

The class Coelenterata includes the Polypes and
Medusz, and in the closest connection with it stands
the interesting class of the Spongiade, especially in-
structive as affording direct evidence of the doctrine of
Descent. The organs of these animals are nearly always .
TYPES AND FAMILIES. 31

arranged radially round an axis, passing through the dor-
sal and ventral pole. The cavity, which in most other ani-
mals—for instance, in man—is termed the abdominal
cavity, the space between the intestinal wall and the
abdominal parietes, is deficient in them; but, on the
other hand, from the stomach proceed in general vari-
ous kinds:of tubes and branchia, which to a certain ex-
tent replace the abdominal cavity. Fig. 2 represents a

 

Medusa, Tiaropsis Diadema, after Agassiz. The darkly-
shaded organs form the so-called ccelenteric apparatus.

Of the Echinoderms, the reader is probably ac-
quainted, at least with the star-fish (Asterias) and the
sea-urchin (Echinus), of which the general form is like-
wise usually radiate. Besides a peculiar chalky deposit,
or greater or less calcification of the skin covering, a
system of water-canals forms a characteristic of this
family. With these are connected the rows of suckers,
which, by protrusion and retraction, serve as organs of
locomotion. On account of the radiate structure pre-
vailing among the Echinoderms, Meduse, and Polypes,
32 THE DOCTRINE OF DESCENT.

Cuvier believed them to be more nearly related, and in-
cluded them altogether; under the name of Radiata. This
similarity, however, is only superficial, for whilst, on the
one hand, anatomy discloses the great difference of the
Coelenterata and Echinodermata, the history of evolution
still more decidedly banishes the Echinodermata from
this position, and connects them more closely with the
next division.

In this, that of the Vermes, the systematizer of the
old school finds his real difficulty; in so many ways do
they deviate from each other, so great is the distance
between the lower and the higher forms; and after de-
ducting the distinctive marks of orders, so little remains
as a common character, so variegated is the host of
smaller scattered groups, and even of single species,
which demand admittance to the system of the Vermes.
If we attempt to describe their typical nature in a few
words, it must be something like this: The Vermes are
more or less elongated, symmetric animals, which possess
no actual legs, but effect their locomotion by means of a
muscular system, closely combined with the integuments,
which frequently become an actual muscular cylinder.
To this we will add, that the perplexities and difficulties
in reference to points of classification are transformed
into sources of knowledge for the adherent of the doc-
trine of Descent.

The relations of the previous family with the type of
the Articulata is so conspicuous, that the “ kinship”
of the two was never questioned, even by the older
zoologists. The very name of one, the highest division
of the Vermes, that is, of the Annelids, or segmented
worms, indicate this connection. This distinctive mark
GRADATIONS WITHIN THE TYPE. 33

of the Crustacea, Arachnida, Myriopoda, and Insecta, is
that their bodies are constructed of sharply-defined rings
or segments, the legs, antennze and mandibles likewise
sharing in this segmented character. A faithful expres-
sion of this segmentation is afforded by the nervous sys-
tem, which lies, ladder-like, on the ventral side, that is,
beneath the intestinal canal, only encircling the gullet
with its anterior loop. The display of segmentation is
favoured by a deposit of horny substance, which gives a
skeleton-like stiffness to the integuments.

The direct reverse is shown in the integuments of
the Mollusca, our mussels, snails, and cuttlefish. For
although so many are supplied with protecting scales
and shells, these are mere excretions from the actual
skin, which remains soft, and characteristically moist
and slimy, owing to the secretions of numerous glands
contained in it, and has an inclination to lay itself in folds,
and form a-mantle-like investment to the body. The
body therefore remains more or less clumsy; it possesses
none of the grace of the Articulata, and especially of
the insect; it is destitute of segmentation, and this de-
ficiency is likewise evinced in the nervous system. This
consists only of a ring, encircling the cesophagus, and a
few smaller ganglia.

We shall most readily come to an understanding as
to the Vertebrata, the family with which man is insepa-
rably united. The essential part is the vertebral column,
that portion of the internal and persistently bony or
cartilaginous skeleton, in which the main portion of the
nervous system is contained.

It is thus established that the systematic classification
of the animal kingdom is based on certain prominent
34 THE DOCTRINE OF DESCENT.

characteristics of form and internal structure; and it is
very easy to select from every type forms in which the
distinctive marks, comprised in the systematic diagnosis,
may be displayed in full perfection. But this is imme-
diately succeeded by a further observation, that’of grada-
tions within the type. When we previously compared
the polype and the bee, and were obliged to assign to
each a very different rank, a portion of this difference
of grade is certainly due to the difference of the family;
but the forms united by family characteristics likewise
diverge widely from each other, and the systematist
speaks of lower and higher classes within every type, of
lower and higher orders within every class.

Reason is compelled to this by the same considera-
“tions which forced themselves upon us in the comparison
of the polype and the bee. Why does the mussel stand
lower than the snail? Because it does not possess a head,
because its nervous system is not so concentrated and
so voluminous, because its sensory organs are more de-
fective. In one, as in the other, the structural material
is present in quantities sufficient for the completion of
the type; but in the snail it is more developed, and the
single circumstance of the integration of various parts to
form the head confers a higher dignity upon the snail.
It is needless to illustrate this gradation within the fami-
lies by further examples; the most superficial compari-
son of a fish with a bird or a mammal, of one of the
parasitic crustacea with a crayfish or an insect, shows,
as the older zoology represented it, that in the actual
forms the ground plan, or “ideal types,” find very di-
versified expression.

A further result of this descriptive inquiry is the
TREE-LIKE GROUPING. 35

tree-like grouping of the members of the same family.
The reciprocal relations of the various families can-
not be represented in a simple line; though in former.
days more importance was attributed to the general
indications of the relative value of the types. On the
other hand, descriptive zoology had long been compelled
to devise tables of affinity for the systematic subdivisions,
descending even to species according to the criterion of
anatomical perfection; and these found expression only
in diagrams of highly ramified trees. Branches ap-
peared which terminated after a brief extension; others
are greatly elongated with numerous side branches; in
every branch characteristic phenomena and series are
made manifest,

Let us attempt it with the Vertebrata, for example.
Even with the fishes we fall into great perplexity;
which to place at the end as being the highest. But
take which we will, the sharks or our teleostei, the am-
phibians cannot be annexed in a direct line, nor does the
elongated branch line of the latter merge, as might be
imagined, into the reptiles. The birds, on their side,
offer a sharp contrast to the mammals, and this separa-
tion and divergence extend to all the subdivisions. We
must figuratively represent family branches, clusters of
genera, and tufts of species, which latter ramify into
sub-species and varieties. With this representation of
the tree-like distribution of the system, we shall gladly
revert to the comparison of the members of different
types, with reference to their functional value. The bee
in itself is manifestly a far more complex organism than
the lowest fish-like animal, the lancelet; and in these two
we compare a low form of a high type, and a high form
36 THE DOCTRINE OF DESCENT.

of a low type. By varying and combining comparisons
of this sort, and taking account of the points of connection
between the various types, to which we shall immediately
refer, the figure of the systematic trees completes itself
into one vast tree, of which the main branches are rep-
resented by the types. |

Had the systematizers of the old school been familiar
with the construction of plants and animals, they would
have first established the diagnoses and distinctive char-
acters, and then called to life the types and their species:
for their chief torment has been, that the diagnoses are
liable to so many exceptions, and that the characters
of the fundamental forms are without any absolute value.
Roughly and generally speaking, polypes are radiate in
form, but not a few are bilateral, or symmetric on two
sides. Most snails possess well-marked mantle-folds, but
we can scarcely speak of the mantle of many thoroughly
worm-like slugs.

Head and skull seem an inalienable mark of the
vertebrata, yet the lancelet has no such head, but merely
an anterior end. Nevertheless, it may be objected, it
has a vertebral column; yet this, the special badge of
nobility of the vertebrate animals, like the auditory ap-
paratus, and the notochord, is, even if only transiently, a
possession of the Ascidians, a class of animals which
in their mature condition do not bear the remotest re-
semblance to the Vertebrata. ‘When we become aware
of these deviations from so-called laws of form and
structure, seemingly well established, we are prepared
for a manifest failure of the system, in regard to con-
necting forms, and forms of uncertain position in the
system.
INTERMEDIATE FORMS. 37

If the result of the systematic sifting and arrange-
ment within the individual types can be comprised in
diagrams of trees, forms intermediate to the members
of the types, classes, orders, &c., follow as a matter of
course. For if the figure be correct, every ramification
of the branches must include species diverging very
slightly from the species standing in the lowest portions
of the bough from which it branches off. And thus all
systematizing, in fact, amounted to the insertion of the
right intermediate forms between each two forms devi-
ating from each other in a higher degree; nay, in some
cases, intermediate forms were sought where none exist.
The older zoology always regarded the duck-mole (Or-
nithorhynchus) as the mammal most nearly allied to the
birds, though the cause of the bird-like appearance of the
lowest mammal known, is by no means to be sought in
a direct relationship, but in a remote cousinhood.

But we must draw attention, not to these connect’ng
forms, which natural history assumes as perfectly self-
evident, but to those which are, as it were, inconvenient
to systematic description, and threaten to render illusory
the groundwork so laboriously gained. There are some
fish-like animals, the Dipnoi, (Lepidosirens and_ their
congeners) with the characters of Amphibians. The
Infusoria possess many characteristics of the so-called
primordial animals, but in other ways they differ from
them, and point to the.lowest Turbellaria. A minute
animal inhabiting our seas in countless multitudes, 1. e.
the Sagitta, is neither a true annelid nor a legitimate
mollusc. The Peripatus, a creature recently and very
thoroughly investigated, combines in a highly remark-
able manner the characteristics of the Articulata; for in-
38 THE DOCTRINE OF DESCENT.

stance, tracheze with those of the Annelida—as the lateral
organs.

The combination is inexplicable and paradoxical from
the point of view of the old system.

Example after example might be thus accumulate]
to show that the rigid partitions of the system are scarcely
raised before they are again broken down in every direc-
tion; and this in direct ratio with the increase of special
science. As before said, descriptive natural history neces-
sarily gained this experience. It then spoke of excep-
tions and deviations, without being able to adduce any
reason why the classes and types should be able to break
through their limits, and indeed most frequently without
feeling any need of accounting for the failure of the rigid
system.
III.
The Phenomena of Reproduction in the Animal World.

THE faculty of giving existence to new life is part of
the evidence of life. A crystal does not reproduce
itself, it can only be resolved into its elementary con-
stituents; and in the natural course of things, or in an
artificial manner, these may be induced to form another
crystalline combination. But this is not that con-
tinuity of reproduction which links individual to indi-
vidual, is not procreation wrapped in a cloud of mystery.
Herein, it seems, consists a stubborn opposition. Yet,
if the distinction between animate and inanimate nature
has been recognized as one not entirely absolute;
especially if the possibility, nay even the necessity, has
been perceived of the primordial generation or parent-
less origin of the lowest organic beings from inorganic
matter (of which more hereafter), and if the nature of
nutrition and growth is understood to be entirely
dependent on the power of obtaining material,—the
mystery of reproduction henceforth disappears. Genera-
tion is no longer a mystical event; and the origin of
an organism in or from an organism, the emission or
development of innumerable germs, may, like the
origin of a new crystal, be analyzed into the motions
of elements, as yet accessible only to the eye of imagina-

4 39
40 THE DOCTRINE OF DESCENT.

tion. By this we mean to say that in the province of
reproduction the limits of inquiry are neither narrow nor
peculiar. We will therefore now proceed to describe the
process of reproduction and development in the animal
kingdom.

If, as must be generally admitted, the most essential
characteristics are common to the highest and the lowest
life,—and it is only the complexity of the vital processes,
together with the variety of the parts by which they are.
performed, that give rise to graduated diversities,—it
will, of course, be in the simplest organisms that we shall
most readily recognize the nature of these vital processes.

The simplest beings, discovered by Haeckel, such as
the Protamceba, those minute albuminous masses of sar-
code, increase to a certain extent. Why these dimensions
should vary only within definite narrow limits, and why,
on attaining a certain extent, the molecules should
gravitate into two halves, we do not know; at any rate
it is an affair of relations of cohesion, theoretically
susceptible of computation. It is enough that at a
certain size the coherence of the parts is loosened in a
central zone, the individual becomes faithless to its
name, and divides into two halves, of which each form
the moment of separation begins an individual life,
while from the commencement of the fission prepara-
tions were being made for their self-dependence. This
is the simplest case of reproduction, a multiplication
by division. Frequently, however, it does not stop
at bisection; the motion of the minute constituents,
which causes the fission, proceeds in such a manner that
the halves are again divided, and the quarters yet again,
the whole being thus divided into a greater number of
FISSION—GEMMATION. 4I

portions, and the parent-creature is resolved into a swarm
of off-shoots. :

This multiplication by mere division of the mass pre-
supposes that the organism thus reproducing itself pos-
sesses no high complexity. The bisection of a beetle
or a bird is inconceivable as a means of propagation.
Yet Stein’s valuable observations on the reproductive
process of the Infusoria, make us acquainted with organ-
isms standing far above these simple so-called Monera,
of which the subdivisions undergo a series of profound
metamorphoses, before separating as self-dependent indi-
viduals. This transformation, combined with fission,
leads to reproduction by gemmation.

As the fission of these low organisms depends on the
attainment of a certain limit of growth conditional on
adequate nourishment, the case now more frequently
occurs that the individual discharges the superfluity of
material obtained at a definite part of the body, and
forms a bud or gemmule. We are already acquainted
with reproduction by gemmation in the simplest organ-
ism, the cell; for all healing and cicatrization in higher
beings, even to the re-integration of the mutilated limbs
of amphibians, is effected only by the reproduction by
fission and gemmation of the elementary morphological
constituents. But it lies in the nature of the process of
gemmation, that it should extend far higher than fission
in the scale of organisms; it is the origination of a new
being from one already existing, the latter, meanwhile,
preserving its individuality wholly or for the greater
part, and yet being able to transfer to the progeny its
own characteristics in their full integrity.

The simplest case of gemmation is where the parent
42 THE DOCTRINE OF DESCENT.

animal produces one or more gemmules similar to itself,
capable in their turn of producing similar gemmules. Of
this, every collection of corals gives numerous examples,
and shows how the diversified appearance of the several
genera of coral depends merely on minor modifications
of this mode of reproduction. Yet single corals exist
in which, on careful comparison, not only may accidental
deviations be already discerned, but regularly recurring
variations between parent and progeny, as Semper has
recently shown in Madrepores and Fungiform corals.
This brings us to the highly-important phenomenon of
Alternate Generation, which we must elucidate by a few
examples before entering upon the nature of sexual repro-
duction.

Figure 3 shows in A a polype-shaped being with
cruciform tentacles, on which the discoverer, Dujardin,
bestowed the generic name of Cross-polype, or Stauri-
dium. This animal, growing like a polype upon a stalk,
forms above its lower cross, gemmules which make their
appearance as spherical balls, gradually assume a bell-like
shape, and detach themselves on attaining the structure
and form of a Medusa or sea-nettle. The Medusa (termed
Cladonema Radiatum, Fig. 3 B) is thus the offspring of
its utterly dissimilar parent, the Stauridium; it repro-
duces itself in the sexual method, and from its eggs pro-
ceed Stauridia. The two generations thus alternate; the
cross-polype is an intermediate generation in the develop-
ment of the Medusa, so that the sexual generation never
originates directly from its egg.

In the tape-worm, we have an illustration of the same
process, only in a somewhat more complicated form.
It is known that from the intestinal canal of individuals
ALTERNATE GENERATION. 43

afflicted with tape-worm, issue so-called somites or seg-
ments of the tape-worm. These somites are usually
filled with such an extraordinary number of ova that
they seem like mere packets of eggs. It appears, how-

 

FIG 3.

ever, from the evolutionary history of the tape-worm,
and its relations with other annulosa, namely with
leeches and Turbellaria, that notwithstanding their in-
completeness and deficiency of organs, these somites are
equivalent to sexually mature individuals; or, according
to Haeckel’s definition, are endowed with personality.
If the tape-worm now comported itself like most other
animals, somites would be directly developed from its
eggs. But to this there is a very circuitous proceeding.
44 THE DOCTRINE OF DESCENT.

If the egg of a tape-worm, by chance and good luck,
strays into a congenial stomach,—for example, the egg
of the human tape-worm, Tcenia solium, into the stomach
of a pig, the embryo wanders out of the stomach in
which it, quitted the egg, and makes its way into the
muscles, where it swells out into a sort of cyst. This
cyst is the first intermediate generation. It produces a
peg-shaped gemmule, which, however, fails of its object
as long as the “ bladder worm,” or “ Gargol,” remains in
the flesh of the pig. It is only when this comes, raw or
imperfectly cooked, into the human stomach, that the
time has arrived for the release of the pupa. It emerges
from its parent the cyst, and the pupa, in which we now
recognize the head and thorax of the tape-worm imago,
represents a second intermediate generation. Its pro-
ductiveness is forthwith displayed; it becomes elon-
gated, and as its ribbon-like form increases, shooting
out from the posterior portion of the cervix, the more
distinctly marked become the transverse stripes and
“ somites;” in other words, the individuals of the third
or sexual generation.

In the evolutionary cycles just discussed, there is an
alternation of asexual and sexual reproduction; and be-
fore examining some other cases of asexual multiplica-
tion, we must make ourselves acquainted with the facts
of sexual reproduction.

The characteristic of this is, that it requires for the
generation. of the new individual the union of two
different products or morphological elements, the ovum
and the sperm. The ovum is always, in the first in-
stance, a simple cell, of which the nucleus is termed the
germinal vesicle, and the nucleole the germinal spot.
GERM-CELLS. 45

In many animals it is provided with a sheath or mem-
brane of its own; in others it remains naked, and in that
case frequently displays the remarkable movements of
protoplasm. The germ-cells of different classes of ani-
mals vary considerably in.their microscopic dimensions;
nevertheless, in the whole animal kingdom, from the
sponges and polypes up to the mammals inclusive of
man, they are essentially similar. Nor do non-essential
differences appear until the primitive germ-cell is more
abundantly provided with yelk and albumen, and has
surrounded itself with a specially thick and perforated
shell, as in insects and fishes, or with a peculiarly
formed sheath, in the shape of a double concave lens,
as, for instance, in some Turbellaria. As a rule, the
ova are formed in special organs,
the ovaries. The other sexual
element, the sperm, contains, as
its peculiar active constituents,
the spermatozoa (fig. 4 s), which
consist of a pointed, elliptic, or
occasionally of a hook-shaped,
head, and a thread-like body. As long as the sperm is
capable of fecundation, the filamentous appendage per-
forms serpentine movements, and the development of the
spermatozoa from cells, as well as the comparison of their
movements with the vibrating movements of ciliated and
flagellate cells, enable us to recognize them also as modi-
fied cell structures.

The vehement dispute of last century between Evo-
lutionists and Epigenists has now a merely historical
interest. The former maintained that either in the ovum
or in the sperm-corpuscle the whole future organism

 

FIG. 4.
40 THE DOCTRINE OF DESCENT.

was prefigured in all its parts, and that it hence required
only the development of the infinitely minute organs
already existing. The others, who carried off the victory,
saw in the ovum the yet undifferentiated material which
subsequent to fecundation had still to be transformed into
the various morphological elements and organs. But it
is scarcely twenty years ago since the process of fecunda-
tion was discovered, and since it was proved that at least
one sperm corpuscle, and, as a rule, several or many,
must penetrate into the interior of the ovum and unite
materially with its substance in order to produce an
effectual fecundation.

The course of our demonstration obliges us to place
sexual in sharp contrast with asexual genesis. But
here, again, recent times have produced a series of
equalizing and concilatory observations which must
not be neglected by us, bent as we are on tracing the
antecedents of the doctrine of evolution, and demon-
strating the transition taking place throughout organic
Nature. In the cases of alternate generation selected
above, the generations which do not produce ova and
spermatozoa, reproduce themselves by external gemma-
tion. Now, there is manifestly no great physiological
difference if the deposition of the material from which
the progeny is formed takes place, not externally, but
in and by special internal organs. One of the most
familiar examples occurs in the evolutionary cycle or al-
ternate generation of the genus Distoma of the Entozoa.
In the ventral cavity of one larval generation arise cell-
spheres, or germs, which develope into the second genera-
tion—the Cercaria.

Great excitement was likewise aroused by the dis-
DEVELOPMENT OF UNFERTILIZED OVA. 47

covery of the germ-formation of the larve of some dip-
terous insects (Cecidomyia, Miastor). In the ventral
cavity of the maggots of these flies arises a second gen-
eration of maggots, of which the origin was primarily
attributed to a simple germ-formation, until it was shown
that these germs proceed from the situation of the sex-
ual glands (which in many insects are developed at a
very early stage), and must therefore be regarded as un-
fertilized ova. The second generation of maggots lives
at the expense of its parent, consumes its fatty substance,
and afterwards destroys the other organs; while of the
pelican-like parent nothing finally remains but the skin,
as a protecting cover to the offspring, which very soon
emerges.

Without mentioning other cases in which it may be
questionable whether germs or unfertilized ova attain
development, we will point out a few of those in which
development, without fecundation, is established with
complete certainty. The queen bee, partly from the
natural course of its life, partly from various accidents
in which fecundation could not take place, lays regularly
a number of unfertilized eggs, from which issue drones,
or male individuals; or if exceptionally eggs are laid
by workers, which are imperfectly developed female
bees not susceptible of fecundation, these eggs likewise
produce drones only. Von Siebold’s highly interesting
experiments on the reproduction of a wasp (Polistes
Gallica), have shown that the hybernating fertilized
females, who found a new colony in the spring, deposit
eggs whence issue female individuals, and occasionally
males. This virgin generation then produces eggs from
which males are developed. With various butterflies,
48 THE DOCTRINE OF DESCENT.

on the contrary, the unfertilized eggs produce females
only; and it is the same with several of the lower crus-
taceans.

We will now revert to the consideration of the evolu-
tionary processes displayed in sexual reproduction after
fecundation has taken place. Development invariably
commences with a process of cell-formation, the bifurca-
tion or formation of the germinal membrane, after the
completion of which, instead of the one primitive cell,
a large number of cells are usually in existence, as the
material for the distribution and construction of the em-
bryo. Ova developing parthenogenetically, without
fecundation, likewise commence their development by
this multiplication of cells; and even the ova of ani-
mals, in which development never takes place without
previous fecundation, exhibit an incomplete bifurcation,
if not fertilized at a certain stage of maturity. This
process, it is true, has been as yet demonstrated only in
the ova of the frog and the domestic fowl; but these
cases are sufficient to divest the bifurcation of the char-
acter of an independent phenomenon, exclusively re-
stricted to sexual reproduction.

Even before the appearance of C. E. von Baer’s really
classical and fundamental work on the “ Evolutionary
History of Animals” (Entwickelungsgeschichte der
Thiere),® the view, founded on incomplete observations,
had become established, that in the various stages of
their development the higher animals passed through
the forms of the lower ones. In this, natural philosophy
did not confine itself to the limits of the types; and
hence did not pause at the hypothesis that the mam-
malian embryo was successively a fish, an amphibian,
TYPES OF DEVELOPMENT. 49

and in a certain sense, by a particular gradual evolution
of the organs, a bird also, but made the-embryo like-
wise repeat and surpass the lower types. To this false
tendency, acting on vague analogies, a stop was put by
the great naturalist just named. He showed that a num-
ber of coincidences might, indeed, be demonstrated be-
tween the embryo of the higher and the permanent form
of the lower animals, but that this resemblance rested
essentially on the fact that in the embryo of the higher
animal the differentiation of the general fundamental mass
had not yet set in, and that in the progress of development
it passes through stages which are permanent in the series
of inferior animals.

On the other hand, he positively repudiated the asser-
tion that the embryos of the higher types actually pass
through forms permanent in the lower ones. He says
that the type of each animal seems from the first to
fix itself in the embryo, and to regulate its whole
development. As regards the vertebrate animals in par-
ticular, the further we go back in the history of their
development, the more do we find the embryos alike,
both on the whole and in the individual parts. “ Only
gradually do the characters appear which mark the
greater, and later those which mark the smaller divisions
of the Vertebrata. Thus from the general type the special
one is evolved.”

Von Baer thus held that the analogy consisted only in
the embryonic states of the various animal forms; but
he was obliged to go beyond the circle of the types, and
he thought it probable that among all embryos of verte-
brate, as well as invertebrate animals, developed from a
true ovum, there is a conformity in the condition of the
50 THE DOCTRINE OF DESCENT.

germ at a period when the type has not yet manifested
itself. This led him to the question, “ Whether, at the
beginning of development, all animals are not essen-
tially alike, and whether a common primordial form
does not exist for all?” “It might,” he finally thinks.
‘be maintained, not without reason, that the simple cyst-
like form is the common fundamental form from which
all animals are developed, not merely in idea, but his-
torically.”

When the barrier which it was formerly thought
necessary to erect between asexual multiplication and
multiplication caused by fecundation had been recog-
nized as non-existent, and it was perceived that all
development amounts to the multiplication and meta-
morphosis of the primitive germ or egg-cell, the cell
was necessarily regarded, in the acceptation of the older
investigators, as the common fundamental form. But
although the descriptive history of evolution does not
go back to this elementary organism, and considers
even the bifurcation as merely a preparation for actual
development, at any rate the earliest rudimentary larval
conditions of different types may be compared with each
other.

The discoveries of the last ten years with reference
to this subject are so numerous, and such striking
analogies have been advanced, that we must needs go
much further than, at that time, was possible for Von
Baer. It is not merely a question of those general
analogies in the segregation of tissues from an indiffer-
ent rudimentary mass, but of homologies in the distri-
bution, form, and composition of the embryos and larve,
of which the after effects are of profound importance
EARLIEST CONDITION OF LARVA. 51

to the later and actual typical impress. With this object,
let us consider the larva of a calcareous sponge at the
stage which Haeckel has designated as the Gastrula
phase.

The diagram gives the section of a larva of this
description, which at this period is nothing more than a
stomach provided with an orifice (fig. 5 0); its wall con-

 

FIG. 5.

sists of two strata, or layers of cells. The cells of the
external stratum are distinguished from those of the
inner one by their elongated form, and the possession of
filaments serving as organs of locomotion. All subse-
quent development and differentiation, certainly not
very ifnportant in the sponges, may be traced to modi-
fications of these two membranes; the external mem-
52 THE DOCTRINE OF DESCENT.

brane (Ectoderm, or Exoderm) and the internal mem-
brane (Entoderm). And this phase of the ciliated
larva, with its twofold strata, its primitive ventral cavity
and mouth, recurs in the Coelenterata, with slight varia-
tions in the Echinoderms, in some of the Annulosa, in
the Sagitta, the Ascidians, and the Lancelet. From
the analogy of all these animals, and especially of the
last, we shall be able hereafter to derive important
inductions.

But if no weight be attached to the presence of
these filaments of the external layer, which is, moreover,
justified by the relation of the filament to the cell, and
if it be acknowledged as the essential significance of
the larval arrangement, that from its two lamine the
collective organs derive their origin, then to the animals
above enumerated must be added, not only almost the
whole of the Articulata, but likewise the remainder of
the Vertebrata, as in them, immediately after the appear-
ance of the primitive striz, follows their separation into
two cell-layers, or membranes. Respecting the deriva-
tion of the third or middle germinal lamina, and the
share of the two primitive laminz in its formation, ob-
servers are not agreed.

Only from this point does the development of the
great animal groups take various directions, and it is the
immortal merit of Von Baer to have fixed these types of
development, independently of the fundamental forms,
established by Cuvier on zoological and anatomical con-
siderations, and he thereby laid a far deeper foundation
for the existence of these types. We will illustrate our
meaning by two examples.

When the ovum of the articulate animal has sur-
TYPE OF DEVELOPMENT OF ARTICULATA. 53

rounded itself with a germinal membrane, a portion of it
thickens into a long germinal stria, resembling an elon-
gated ellipse. This is the rudiment of the ventral side of
the future animal. A groove then divides it into the two
germinal Jaminz, and transverse strize next make their
appearance, the indications of the so-called primordial
segments. The symmetrical disposition of the organs,
and the integration of the body out
of consecutive segments, is herewith
initiated. All further development
emanates from these primordial seg-
ments, which are the standard of the
Annelids or higher Vermes; while in
the Articulata, projections and ap-
pendages of these segments develop
into feelers, manducatory apparatus
and legs, and by their heterogeneous
integration in the regions of the
head, and of the middle and posterior
portions of the body, give rise to the
vast variety within the type. In each
particular case we see what is special FIG. 6.

emanate from what is more homogeneous and undiffer-
entiated, and this is likewise corroborated by the more
advanced phase portrayed in the diagram (fig. 6). It
represents the embryo of the great black-beetle (Hydro-
philus piceus) on its ventral side. The antenne (f), the
three pair of oral appendages (m), and the three pair of
legs, are as yet little distinguished. In the further course
of development, the lateral portions grow towards the
back, in the centre of which they finally meet. As
compared with the Vertebrata, it may hence be said

 
54 THE DOCTRINE OF DESCENT.

that the Articulata have their navel on their backs.
Conversely, it is the characteristic of the evolutionary
type of the Vertebrata that the position of the germ
corresponds with the dorsal side of the animal. The
formation of the dorsal groove, which subsequently
closes to form the canal of the spinal cord, as it is
gradually enveloped in a sheath growing from below,
is followed by the formation of transverse plates, the
pre-vertebral plates. The side plates lying outside of
these grow towards the ventral side, and finally merge
in the navel. The position of the actual vertebral
column, consisting of separate vertebre, is always
originally occupied by a cartilaginous band, the noto-
chord (chorda dorsalis), and, as from this axis, the germi-
nal matter transforms itself into a tube above as well as
below,—into the spinal marrow with its sheath, and the
ventral cavity with the intestinal canal_Von Baer con-
sidered this mode of development as bi-symmetrical.
The development of the Articulata he regards as simply
symmetrical, and the development of the Molluscs
he designated as massive. The justification of this is
that the elongation produced by segmentation and the
repetition of similar parts and sections of the body im-
plicit in segmentation generally,—the metameric forma-
tion, as it is termed by Haeckel,—is totally foreign to the
Molluscs.

We must now again repeat, that somewhat extensive
observations of the evolutionary forms of different ani-
mals lead at once to the belief that the embryos and
evolutionary phases of higher animals are transiently
more closely related to the complete and definitive con-
ditions of the lower animal-forms, at least of the same
SYSTEMATIC DEVELOPMENT. 55

family; whence arose the fixed idea that the embryo of
the higher animals passes through the forms of the lower
animals. When natural philosophy, more especially in
Germany, had elaborated this doctrine in a rather fan-
tastical manner, and had proclaimed that Man was the
sum of all animals, in structure, as well as in develop-
ment, ‘‘ the doctrine,” says Von Baer, “ of the uniformity
of individual metamorphosis with the vague metamor-
phoses of the whole animal kingdom necessarily acquired
great weight, when, by Rathke’s brilliant discovery,
germinal fissures were demonstrated in the embryos of
mammals and of birds, and the appropriate vessels were
soon afterwards actually revealed.”

The exaggerations and false inferences drawn from
general analogies, and the vague ideas of types hover-
ing above the whole, and regulating individual develop-
ment, were wittily chastised by Von Baer.

“To convince ourselves that-a doubt as to this doc-
trine is not utterly groundless, let us imagine that the
birds had studied the history of their development, and
that it was they who now investigated the structure of
the mature mammal and of man. Might not their physio-
logical manuals teach as follows?—‘ These quadrupeds
and bipeds have much embryonic resemblance, for their
cranial bones are separate; like ourselves during the
first four or five days of hatching, they are without a
beak; their extremities are tolerably like each other,
as are ours for about the same time; not a single true
feather is to be found on their bodies, only thin feather-
shafts, so that, even in the nest, we are more advanced
than they ever become; their bones are not very hard,
and like ours, in our youth, contain no air at all; they

5
56 * THE DOCTRINE OF DESCENT.

are utterly destitute of air-sacs, and their lungs, like ours
in early infancy, are not full-grown; a crop is completely
wanting; a gullet and gizzard are, more or less, merged
in a sac, all conditions very transitory in us, and, in
most, the nails are awkwardly broad, as with us before
breaking the shell; the bats, which appear the most per-
fect, are alone able to fly; not the others. And these
mammals which, so long after birth, are unable to find
their own food, and never rise from the ground, fancy
themselves more highly organised than we?’”

 

FIG. 7. Fic. 8.

Nevertheless, there remains the fact of the parallelism
of individual development with the systematic series to
which the individual belongs; and, among thousands of
examples, we will select some of the most accessible and
convincing. Polypes have always been placed system-
atically below the Medusz; in the development of many
SYSTEMATIC DEVELOPMENT. 57

Medusze (comp. Fig. 3, p. 43), a polype-like condition is
interposed. The crinoid (Comatula), very common in
the Mediterranean, is in its mature condition freely
movable. This definitive development is, however, pre-
ceded by a sessile stage (Fig. 7), during which the body
is attached to a stalk. During the larval period the ani-
mal resembles the permanently sessile genera, which, by
all systematic rules, and by their geological position,
occupy a lower rank in the series of echinoderms. The
crabs, or anourous crustacea, are raised by sundry char-
acteristics above their long-tailed congeners, among
which is the fresh-water crayfish. In the course of de-
velopment they pass through the long-tailed stage, as is
shown in the larva (Fig. 8). It is by the abortion of the
tail, which is employed by the long-tailed species as a
natatory organ, that they become more fitted for run-
ning, and some of them for terrestrial life, as they are,
in a measure, released from a burden.

One of the systematic series included in the Verte-
brata, leads through the reptiles to the birds. Now, if,
in the physiological reflections which Von Baer put into
their beaks, the birds, as will appear later, were mistaken.
in boasting of their feathery garb in contrast to mam-
mals and to man, they have, nevertheless, carried it a
stage further than the reptiles, for the scale is the em-
bryonic rudiment of the feather. Likewise, the tarso-
metatarsal joint of the embryonic bird, with which we
are already conversant (p. 9), and which is distinguished
from the ankle-joint of mammals and of man, by its
lying not between the leg and the tarsus, but in the tarsus
itself, remains, as a definitive condition in the reptile, in
the embryonic condition which in the bird it rapidly
58 THE DOCTRINE OF DESCENT.

passes through. Although mammals are never actual
fish, there ts much that is fish-like in the embryonic
phases of their organs; the embryonic fissures in the
thorax correspond with the germinal branchial fissures;
the formation of the brain may be traced to the complete
brain of the lampreys and the sharks, &c.

In order to refute the doctrine that the embryo passes
through the whole animal kingdom, Von Baer was con-
tent to prove that it never changes from one type to
another. He repudiated the other, and more probable
part of this theory, that is, that, at least within the types,
the higher groups, in their embryonic phases, repeated
the permanent forms of the lower ones, by terming it a
question of mere analogies. The embryo, as it is grad-
ually perfected by progressive histological and morpho-
logical differentiation, necessarily accords, in this respect,
with less developed animals in proportion to its youth.

“Jt is, therefore, very natural that the embryo of the
mammal should be more like that of the fish, than the
embryo of the fish is like the mammal. Now, if the fish
be regarded merely as a less perfect mammal (and this is
an unfounded hypothesis), the mammal must be con-
sidered as a more highly developed fish; and, in that
case, it is quite logical to say that the embryo of the verte-
brate animal is originally a fish.” 1°

We have been somewhat faithless to our intention cf
confining ourselves in this chapter to facts only. The
facts are too apt to provoke reflections, and we have,
moreover, repeated these reflections merely as historical
facts; we must now inquire whether they are really capa-
ble of satisfying us. I think not. It is by no means a
merely histological and morphological differentiation
ABORTIVE ORGANS. 59

which causes the resemblance of the higher incomplete,
to the lower complete forms. To limit ourselves to one
example: it is quite incomprehensible why the ear-bones
of the mammal should be developed, by the circuitous
process of the formation of germinal fissures, if it were a
mere question of histological and morphological differ-
entiation. This explanation fails also with regard to the
whole class of the phenomena of purposeless and abortive
organs, and, finally, the “ evolutionary type” itself as it
rules the groups and regulates individual development,
still remains without an explanation.
IV.

The Animal World in its Historical and Paleontological Development.

It is so easy to observe that the earth’s crust, from the
deepest valleys to the highest mountain top contains
innumerable animal remains, that even antiquity could
not fail to notice it. But some two thousand years
passed by before a correct knowledge was attained of
the relations of these remains to the present world.
Some thought they were sports of nature, products of
creative power leading to no special object, but in a
certain measure to be regarded as exercises preliminary
to the actual creation of life; others considered the fossils
as remains of living creatures, indeed, but of such as
still existed, and which had been destroyed by overflows
and subsequent withdrawals of the sea. The legend of
the universal deluge, especially, derived great support
from this second opinion. Only when, at the end of last
century, the stratification of the earth’s crust was revealed
to science, after the outlines of a history of the solar system
and of 4 special history of the earth or geology had been
indicated by Kant and Laplace, only then arose the
possibility and necessity of a real paleontology, or knowl-
edge of pre-historic life. At the beginning of this cen-

tury it was discovered that the fossils corresponding
60
GEOLOGICAL FORMATIONS. 61

with the stratification of the earth’s crust follow each other
in regular sequence, and that in this sequence they differ
from the present creation, as they do from each other.

We must make ourselves acquainted with the order of
succession of these strata. They are the shelves in
which the vegetable and animal remains lie stored. To
arrange them was certainly possible only by taking the
organisms which they contained as guides or clues. We,
however, shall take this arrangement as our data, and,
with the object we have in view, we shall naturally con-
sider only those strata and rocks in which fossils—using
this word in its widest interpretation—are or might be
contained, those, namely, which are proved to be sedi-
mentary, i.e. aqueous deposits. Our information is lim-
ited to a great part of Europe, numerous districts of
America, and scattered points of the rest of the world.

The following table gives the arrangement of the sedi-
mentary strata from above downwards:—

a. Alluvium.

2. Diluvium.

3. Tertiary formation.

Pliocene.
Miocene.

Eocene.
4. Cretaceous formation.

of English

Sinon. | = White Chalk and Chalk Marl Series.
Turon. = Part of the Chalk Marl Bee P07 of
Kinoman, = Upper Greensand Page’s Ad-
vanced Text
l Book.
Gault.

Neocoman (Wealden).
5. Jurassic formation or Oolite.
Upper White Jura (Malm).
‘62 THE DOCTRINE OF DESCENT.

Middle Brown Jura (Dogger).
Lower Black Jura (Lias).

6. Triassic formation or New Red Sandstone.
Keuper or Variegated Marls.
Muschelkalk.

Variegated Sandstone.
7. Permian formation or Dyas.
Zechstein (Magnesian Limestone or Dolomitic Conglomerate)
Rothliegendes or Red Conglomerate.
8. Carboniferous formation.
Coal Measures.
Millstone Grit.
Mountain Limestone.

g. Devonian formation.

1o. Silurian formation.

iz. Cambrian formation. ‘

12. Laurentian formation.

Although we are not writing on geology, a short
explanation of these strata will be requisite, as their
mutual relations also throw light on the nature and
distribution of the contemporaneous organisms. All
displacements of earth which we now see occurring by
means of rain, rivers, sea and other natural forces
which have taken place in historic times, in short, in
the so-called Present, such as the great delta deposits,
and the moraine formations of our glaciers, are ascribed
to the Alluvium.

It was formerly supposed that its limits might be dis-
tinguished from the Diluvium by the appearance of man,
but as it is now, and always has been impossible to
affirm anything positive respecting that epoch, and as, al-
though a portion of the organisms of which the remains
occur in the Diluvial strata is extinct, much more still ex-
ists, these two formations are inseparably intermingled.

To the Diluvium belong the vast mud deposits of
TERTIARY FORMATION—CHALK. 63

the great rivers, alternating with sand banks, the clay
and loess formations caused by the removal of the soil
by the drainage of the glaciers and the floods of running
water, which at one time increased periodically to a de-
gree truly colossal. The diluvial period, as it seems, in-
cludes, both in Europe and America, a repeated glacifica-
tion of countries and vast portions of the world, of which
the present state of Greenland may now give some idea.

The period of the series of strata, comprised under
the name of the tertiary formation, may -be regarded
as that during which, at least, the skeleton of the pres-
ent continents finally attained its integral configuration.
Within its limits fall the erection and upheaval of the
great mountain chains, the Cordilleras, Alps, Himalayas,
and others; the outlines of the continents were, mean-
while, in constant movement. This phenomenon, how-
ever, persists throughout all formations, and, as the geo-
logical characteristic of the tertiary formation, more stress
should be laid on the separation of the earth’s surface
into climatic zones, approximating to the zones of the
present age. The names of the subdivisions are intended
to indicate the relation of the animals then living to those
of our world, as it was supposed that in the eocene the first
animals identical with present species were to be found,
more in the miocene, and, yet more, in the pliocene.

To the chalk formation belong rocks of very various
kinds, which can be reduced to one great geological
period by means of their contents. If the quartzose
sandstone of Saxon Switzerland represents this forma-
tion in the centre of Germany, it is from the white chalk
of England and Northern France that it took its name.
In America, the sandstone has been in a great measure
64 THE DOCTRINE OF DESCENT.

ground down into sand, and in other places the strata
are purely chalky or marly. But the vagueness of the
limitations of strata in situation, and still more in time,
may be estimated by the fact that we are fully justi-
fied in speaking of the chalk formation now going on,
as is shown by the investigations of Carpenter and
W. Thompson on the constitution of the deep sea-
bottom of the Atlantic. To the early chalk period
belongs a great fresh-water deposit, and likewise the
Wealden, a formation of peat and bog occasioned by
upheavals, which contains a number of remains of fresh-
water-and terrestrial animals, besides a peculiar sort of
coal. :

The oolitic strata appear more definite, mostly lying
regularly over each other in distinct deposits, more rarely,
as in the Alps, raised up by later dislocations. The rocks
themselves, betray that the depositions took place in
wide seas, for the most part calm or deep, and this is
rendered a certainty by the scanty vegetal remains and
the far more abundant animal remains which they con-
tain. In the apparently very sharp limitation of the
oolitic formation, both above and below, the older geol-
ogy found a main prop for the assertion, that compara-
tively quiet periods of long duration alternated with
catastrophes destroying and re-creating everything. To
avoid any misapprehension we must, however, add that
the oolitic period already possessed vast and highly
integrated continents, as it will likewise be seen that
during this era the higher terrestrial animals made their
appearance.

The characters shown by the three great divisions
of the triassic formation are very various, especially as

*
TRIAS—COAL. 65

they are developed in Germany. The German portion,
judging by its influxes, must be regarded as a formation
of strands and bays; its more highly integrated equiva-
lent in the Alps as a huge oceanic deposit. The Muschel-
kalk (which is missing in England), with its layers of
rock salt and rich remains of oceanic organisms, is like-
wise a marine formation. Of the origin of the stratified
variegated sandstone, so-called from its varied colouring,
with its clays, marls, and frequent vast enclosures of
gypsum, we obtain some idea from our present formations
of sandy shores and dunes. Like these, the deposition of
the variegated sandstone afforded but scanty opportuni-
ties of enclosing animal and vegetal remains, but very
notable footprints have been preserved, such as might
now be formed and preserved, if the marks imprinted
on the damp sand were filled up with fine clayey parti-
cles torn by a storm from some adjacent shore, and sub-
divided in the sea.

As the diversified appearance of the superimposed
planes of antediluvian plants and animals of course de-
pends essentially on the nature of their former abodes,
and as the nature of the individual districts of each
plane must then, as now, have influenced the character
of the organisms by which it was inhabited, we will
indicate the causes which thus affect life in its form and
manifold variety. In order to complete our view of the
origin of the Earth’s crust, and the dependence of the
organic on the configuration of the inorganic world, we
will leave a geologist, Credner, to describe the relations
of the dyassic and carboniferous formations: “‘ In regions
where the carboniferous (coal) formation is typically de-
veloped, it consists of a series of stratifications, the lower
66 THE DOCTRINE OF DESCENT.

one chalky (mountain limestone), the middle one con-
glomerated or arenaceous (millstone grit), and the up-
per one carboniferous (coal measures); hence a marine,
a littoral and a marsh or fresh-water formation. It is
easy to imagine the cause of this phenomenon; it de-
pends on the secular elevation of the primzeval sea bottom,
on which was deposited first the marine mountain lime-
stone; secondly, as it rose to the surface, the shingle
and coarse sand of the shore; and finally, on persistent
elevation, the products of marshes, lagunes, and estuaries.
If it now happened that some portions of the infant con-
tinent covered with the latter (that is to say, with the
productive carboniferous strata), were seized with an op-
posite movement, and therefore sank, there would be
deposited on the surface now again gradually becoming
the bed of the sea, precisely similar forms, only in in-
verse order to that which occurred during the period of
elevation.

And, in fact, this phenomenon is exhibited by those
portions of the earth’s surface which shortly after the
formation of the coal measures again sank below the
sea. In Germany and England the productive coal meas-
ures are followed by a sandstone and conglomerate, there-
fore a littoral formation, exactly like the quartzose sand-
stone and millstone grit which underlies them; and above
this a limestone, dolomite and gypsum formation, corre-
sponding to the mountain limestone, the lowest member
of the carboniferous system. On account of the division
which is displayed in profound palzontological and petro-
graphical diversities, the formation thus developed and
composed is designated as the Dyas. The separate
phases of this cycle of occurrences, by which the car-
DEVONIAN AND SILURIAN STRATA. 67

boniferous and dyassic formations were evolved, are ac-
cordingly (reading from above downwards):

5. Deep Sea. Marine | Mountain| Marine |Magnesian
forms. |Limestone.| animals. |Limestone.
4. Subsidence] Littoral | Conglome- Red Sand-
beneath the] forms. rate and stone.
Sea. Sandstone. | Dyas,
3. Quiescence.| Freshwater Coal _.|Terrestrial] Coal mea-
; and measures. | plants. | sures, Red
Marsh forms. , Sandstone,
Coal fields.
i <
2, Upheaval) Littoral | Conglome- Millstone
above the) forms. rate and grit. Carbon
Sea. Sandstone. iferous
1. Deep Sea.| Marine | Mountain | Marine | Carbonife- forma-
forms. |Limestone.| animals. |rous Lime- tion.

 

 

 

 

 

stone.

From this account it is also manifest that in cases of
incomplete elevation, such as took place in North
America, the formation of the middle period is either
disturbed or totally omitted, and that it may depend on
local causes and the duration of the oscillations if, as in
the Russian Permian formations, corresponding to the
German Dyas, the boundaries of the subdivisions are
more or less obliterated.

The two series of strata beneath the mountain lime-
stone, and reaching the depth of more than 3000 and
6ooo metres, the Devonian and Silurian formations, are
the lowest, and therefore the first which clearly bear the
mark of their origin as marine deposits. Both groups
were formerly comprised under the name of Transition
rocks, or Graywacke formation. In them also sandy,
68 THE DOCTRINE OF DESCENT.

clayey, and chalky rocks alternate with one another, al-
ready exhibiting modifications of a local nature, from
which, towards the carboniferous period, issued the first
beginnings of continental upheaval.

The granite, gneiss and slate, which as primary rocks,
or primitive formations, originated before the Silurian
rocks, are for the most part sediments of hot or very.
warm primeval seas, which have undergone manifold
internal changes from pressure and heat. Till recently,
they were likewise termed the Azoic group, as contain-
ing no vestiges of life, when the discovery of the Eozoon
and its unlimited occurrence in the Laurentian strata .of
Canada, proved that the required conclusion to the series
had actually taken place.

With this Eozoon we begin the enumeration of the
antediluvian animals from below upwards. The remains
of this creature consist of a more or less irregular system
of chambers with cretaceous walls, of which the interior
is filled with serpentine or pyroxene. It was attempted
to deny the organic origin of this cretaceous testa, which
may best be compared to the shells of the Foraminifera.
But renewed researches have substantiated that although
in the great mass of the Eozoon rocks occurring in vast
strata, metamorphosis has rendered it nearly, if not quite,
impossible to recognize the true nature of the body, pieces
here and there occur with the chambering so distinctly
marked, and a tubular structure peculiar to the Forami-
nifera, which exclude any other interpretation than that
of a living being resembling the low Foraminifera. This is
of great significance, as the profusion of life met with in
the Silurian and Devonian strata presupposes an im-
measurably long antecedent period during which life
GRAPTOLITES—TRILOBITES. 69

had already existed and gradually increased to the mul-
titudes of the Silurian era. We discover in it but scanty
remains of marine plants, and only nrarine animals; but
these are so heterogeneous and varied in form, that they
alone would oblige us to infer the existence of coasts,
shallow or deep oceanic regions, and a number of geo-
graphical conditions on which we see the variety and
extent of animal life to be dependent. Besides numerous
forms of corals more nearly allied to still
existing families, we find the quite
peculiar group of Graptolites (fig. 9),
which, although not actual polypes,
might be ranged next to the so-called
Medusa-polypes, and thus justify the
inference that preparation was being
made for the appearance of the higher
forms of the Coelenterata, the Medusz.
The Articulata are represented by the
Trilobites (fig. 10, Trilobites remipes),
a crab-like form which recalls the pre-
sent group of the Lamellibranchiata, but
has not hitherto admitted of any closer FIG. 9.
definition, as in none of the many thousand specimens
examined, of the forms (about 2000) known in the Silurian
and Devonian strata, have the legs been preserved. In
these three-lobed crabs, the head, trunk, and tail distinctly
appear, as well as the threefold transverse division. The
two composite eyes already indicate a high grade of or-
ganization. The power of rolling themselves up, which
they have in common with several of the crabs now inhab-
iting shallow waters and coasts, and likewise their general
habit, allow us toinferthatthey also were denizens of coasts.

 
70 THE DOCTRINE OF DESCENT.

The Molluscs were mainly represented by Brachiopoda
and Cephalopoda. However, as Bivalves and Gaster-

 

FIG. Io.

opoda were also in existence, the appearance of this, the
most ancient molluscous fauna known, differs from the
present one only in its numerical proportions, and in the
circumstance, certainly very important, that of the
Cephalopoda the Nautilus alone is found. The Brachio-
poda soon attain to their highest development, and have
lingered on till now in a greatly reduced state. Among
FAUNA OF THE DEVONIAN PERIOD. 71

the Conchifera, the Dimyariz take the lead in the course
of the later period; and with regard to the Gasteropods,
we will merely observe that they constantly increase in
internal complexity and variety as they approach more
recent periods, and that the terrestrial and fresh-water
species are occasionally found in the carboniferous forma-
tion, though in number and variety they belong primarily
to the Tertiary era. To the Cephalopoda we must return
again. Ofthe Vertebrata in the Silurian strata we know
only the remains of peculiar Fishes whose kindred must
be sought among the sharks and rays.

In the period of the Devonian or upper Transition
rocks, the surface of the earth had assumed, at least in
places, a more smiling appearance. Here begins the
first record of terrestrial plants. As to the character of
the fauna, the rapid decrease of the Trilobites is worthy
.,of notice, and the appearance of the important genus of

the Cephalopoda, Clymenia, subsequently replaced by the
Ammonites. Above all, we must note the increased
abundance of fish which still form the sole representa-
tives of the Vertebrata, and held undisputed sway in the
seas of that period. Besides the sharks, there are the
mailed Ganoids. It is true, the fish, the hinder part of
which is here portrayed (Fig. 11, Palzeoniscus), belongs
only to the upper Coal and Zechstein formation; but it
is necessary even now to point out the characteristics
of the true Ganoids which floundered about the Silurian
seas in somewhat extraordinary forms. Agassiz terms
them Placoids, from the rhombic scales, provided with
a layer of enamel highly favourable to preservation, and
covering the whole surface in oblique rows.. The ver-

tebral column, as in.the sharks, enters the upper flap of
6
F2 THE DOCTRINE OF DESCENT.

the tail and renders it strikingly unsymmetrical. The
Ganoids are, as comparative anatomy has proved with

 

FIG. Il.

certainty, a development of the shark-like fishes, if not
decidedly of a higher grade. The Ganoids, therefore,
presuppose the shark.

The carboniferous period owes its name to the enor-
mous accumulation occurring in its midst, of the re-
mains of terrestrial plants, fern-like Calamites, and
more especially of Sigillaria and Lepidodendra, stand-
ing between vascular Cryptogams and Conifers. They
formed tropical bog-forests, such as Franz Unger some
years ago attempted to restore in an ingenious compo-
sition. In these steaming primeval forests, differing
from the early beginnings of antecedent periods by
their extent and luxuriance, new phases of animal
life become manifest—scorpions, myriapods, and in-
sects—in other words, air-breathing Articulata, and
likewise the first air-breathing Vertebrata. The latter,
the Cheirotheria, or Labyrinthodonta (colossal Batra-
chians) possess pre-eminently amphibian characters, and
exhibit, for example, several important characteristics of
the Batrachian skull, whereas their skin-covering recalls
FAUNA OF THE TRIAS. 73

the scale-armour of the Saurians. Thus we find char-
acters combined which are subsequently divided among
different groups. There are also traces of huge sea-lizards.
But here, and likewise in the magnesian limestone for-
mation, these amphibian-like animals still keep in the
background amid the profusion of Ganoids, which espe-
cially characterizes some of the strata of the magnesian
limestone formation, the Kupferschiefer, or cupriferous
marl formation. For the sake of classification, the Zech-
stein is not unfitly supposed to conclude a great period
of organic development: the series of formations from the
Silurian to the end of the Zechstein is termed palzozoic;
and those which follow, the Trias, Oolite, and Cretaceous
formations, are summed up as mesozoic.

The Trilobites, the mailed Ganoids, and others have
now disappeared, and the enormous development of
reptile life stamps this middle period. The Trias as
yet possesses no true Teleostei. The Labyrinthodonta
still predominate; while the Archzeosauros and the Pro-
terosaurus, which had already appeared in the Dyas, are
replaced by more numerous forms approximating to the’
true reptiles. One single discovery in the upper member
of the Trias—the teeth of a predatory marsupial—has
supplied us with the most ancient traces of a mammal.
It might be inferred, even from the petrographic char-
acter of the oolitic strata, that this era must have been,
on the whole, far.more favourable to the development of
animal life than the more perturbed Triassic period, or
that at least a more copious preservation of organic re-
mains might be expected, for the oolitic strata are
mostly depositions which have taken place without dis-
turbance.
74 THE DOCTRINE OF DESCENT.

And so it proves. The Placoids and Ganoids hitherto
predominating in the ocean almost without a foe, now
found overwhelming enemies in the true sea-lizards, or
Enaliosaurians, especially the Ichthyosaura and Plesio-
saura. The head is like a lizard or a crocodile, the ver-
tebral column fish-like, and, as Gegenbauer has shown,
the extremities also recall the simpler fins of sharks.
Their coprolites likewise allow us to infer with full
certainty, a very peculiar construction of the middle
portion of the intestinal canal. They possessed a spiral
intestine like that of the sharks and their congeners.
These animals are therefore noteworthy, not only on ac-
count of their striking external appearance and the part
they play in nature’s household, but, like the Labyrintho-
don, as intermediate and connecting forms of reptiles and
of fish.

Besides these animals, a conspicuous. group of the
marine fauna is that of the Ammonites, which occur
in masses, and next to the Nautili constitute the chief
form of the ancient Cephalopoda, the study of which
has recently promised to contribute essentially to the
decision of the most important points in our science.
In combination with them, the Belemnites abound with
their multitudinous species, originating in the Trias.
They are proved to be the predecessors of dibranchiate
Cephalopoda, which now predominate. On the chalk
plains of Eichstadt and Solnhofen, belonging to the
White Jura, are also preserved impressions, resembling
drawings, of Medusz, which show that even at that time
this class had reached the state in which it still exists.

The terrestrial fauna of the Jurassic period is like
wise enriched by new forms and groups. We find the
FAUNA OF THE OOLITES. 75

first true crocodiles, tortoises, and the most remarkable
variation of the Sauroid type, the winged lizard or
Pterodactyl. It is evident from their well-preserved
skeletons that the wing membrane was stretched, as in
the bat, between the posterior and anterior extremities.
Behind, it extended to the foot, while in front, it obtained
a corresponding addition by the elongation of the little
finger. A first and only bird has likewise been found
in the well-known resting-places of the Pterodactyls, in
the lithographic slates of Solnhofen in Bavaria (Arche-
opterix lithographica). The most remarkable peculiarity
of this bird, recognizable by the most minute impression
of its feathers, is the long tail, bordered by two rows of
rigid feathers. The head is unfortunately crushed beyond
recognition. The inferior order of Mammals already
mentioned, the Marsupials, were also present, as is shown
by the enclosures of the middle Oolite of England and
the upper Oolite of the Purbeck strata.

The ornithic animals of the chalk are more remark-
able intermediate forms than the Archzopteryx, and
these by the hour-glass-shaped centres of the vertebre
are directly connected with the sea-lizards of the Jura;
they also possess teeth; this may, however, be the case
with the Archzopteryx also. We shall return later to
these creatures, which fill up a void hitherto very con-
spicuous. During this new period the Ammonites were
most abundant, and then became extinct, after going
through a stage of degenerate forms which may be ob-
served in the Turrilites, Scaphites, Baculites, and various
others. The prime of the great sea-lizards is also past, but
the marshes of the Wealden period harboured new forms
of colossal land-lizards. The long-tailed cray-fishes are
76 THE DOCTRINE OF DESCENT.

joined by the true crabs, the most highly developed
forms of the class. In the Oolite and Chalk also occur
the chief of the sea-urchin-like Echinodermata. As yet
we have not mentioned the class of Echinodermata, in
order that we might here point out in conjunction several
of the more important phases of their geological occur-
rence. Desor,* a distinguished judge of this class, has
lately examined how in this large group of Echinide
the progress of organization is gradually manifested, on
which occasion he was induced to make some general
reflections on the principle of progressive development,
as applied to the Echinodermata, probably known to all
our readers in their representatives the star-fish and sea-
urchins. If articulate, as well as vertebrate, animals at-
tain a higher grade of development by the differentiation
of the consecutive segments of the body, the superior
unity, and therewith higher perfection, of the Echino-
derm’s body is evinced when the rays, or so-called an-
timera, give way to the unity of the whole.

The more distinct these elements are, that is to say,
the more independent they remain, the lower is, not only
the articulate animal, but also the Echinoderm. Accord-
ingly, the star-fish, and to some extent the feather-stars,
stone-lilies, or crinoids, occupy the lowest rank. But
here, unluckily, paleontological evidence again aban-
dons us. Only so much is certain, that in the older fos-
siliferous strata both divisions are abundantly repre-
sented. A highly remarkable and important intermediate
form is also known, found in the upper Silurian strata
of Dudley (Eucladia Johnsoni), the more important as
but few transitional forms between one order and another

* Bulletin de la Société des Sciences Naturelles de Neufchatel, IX. 2.
TRANSFORMATIONS OF THE ECHIN&. 77

have been hitherto discovered, The relation of the star-
fish to the sea-urchins is still indistinct. On the other
hand, the bridge from the stone-lilies to the sea-urchins
is tolerably apparent. The true Crinoids are sessile, and
with them are connected, in the -carboniferous forma-
tion, the no longer sessile Cystoids and Blastoids, with
which are associated the Tesselle, more resembling
the sea-urchins. Now the Dyas and Trias are still poor
in true Echini; the Oolite, on the contrary, very rich;
and in this great period the extraordinarily heterogeneous
transformations of the Echinide are slowly accomplished,
and may be traced, step by step, from the Lias, the earliest
oolitic formation, to the coral limestone. At first the
Cidaride predominate; they are joined in the Oolite by
the Echinoconide and Cassidulide. A sharper distinc-
tion of species is characteristic of the later strata of the
Upper Jura.

Desor shows how this development, accompanied by
temporary quiescence, is connected with the nature of the
sea-bottom at the time. ‘“‘ The law of progress,” he says,
“is displayed in the circumstance that it is the lowest of
the Echinz, the Regularee and Endocyclicz, which pri-
marily appear, first in the form of the Tessellz, then as
Cidaride; while the most perfect Spatangz, with the
most distinctly marked bilateral form, make their ap-
pearance last of all. Between these extremes we find
a host of genera and species distinguished from one
another by mere shades, so-that of two allied genera it is
often difficult, nay, impossible, to state which is the more
perfect. Progression is only to be shown collectively; in
the concrete case it can rarely be demonstrated.”

The Echinz still predominate in the chalk. Recent
78 THE DOCTRINE OF DESCENT.

discoveries of analogous animals, with soft and still flexi-
ble integuments, confirm what was theoretically extremely
probable, that from them proceeded the highest existing
. order of the Holotkuria or Sea-cucumbers; and thus the
division of Echinoderms conforms to the universal experi-
ence of the ascent from the lower and undifferentiated to
the higher forms.

With the Tertiary period dawns the state of things
now existing. Palms and arboraceous plants character-
ize the vegetation. The animal world has likewise re-
mained essentially the same from the earliest sections of
the Tertiary period until now, as we shall more elab-
orately set forth in the chapter on Geographical Distri-
bution. In the most ancient formations the Fishes, in
the middle the Reptiles, were conspicuous in the world
of life as the representatives of the highest development;
now when the continents, not indeed without sundry
local oscillations, are approximating to their present con-
figuration, the impress of the Mammalia becomes pre-
dominant. Under the influence of elevations and depres-
sions, of several glacial periods, and the more sharply
defined limits of the climatic zones, frequent displace-
ments occurred in the vegetal and animal world, ac-
companied by differentiation and further development.
As we have already mentioned, the course of our inquiries
will bring us back to this subject.

At the time when geologists believed in the rigid parti-
tion of the earth’s periods of development and the sharply
separated succession of the evidence in its favour, that is
to say, of the systems of stratification, the fixed concep-
tion of a fossil was, that whatever had lived before the
appearance of man on the threshold of the Alluvial
GENERAL CHARACTER OF ANTEDILUVIAN WORLD. 79

period was fossil. It has been proved that the existence
of man is far more ancient; that species and races which
surrounded the cradle of mankind have become extinct;
hence that they, like the Mammoth, for example, are
fossil to us only, and not to our diluvial forefathers;
while many other animal forms which existed before man
have been preserved till now. On the whole, from the
Tertiary period forwards, the herbivorous Mammals pre-
cede the Carnivora. The monkeys appear only shortly
before man. /
Notwithstanding many gaps in the paleontological
record, the progress of development is manifest in the
organic world, including the vegetal kingdom. No fossil
animal controverts the system. On the contrary, the
most varied adjustments and accommodations are af-
forded by the antediluvian animals. If, for instance, the
present Pachyderms are sharply distinguished from the
Ruminants, an unbroken bridge between them is estab-
lished by the extinct forms. If the present time shows us
only single scattered genera of the Edentata, the Diluvial
period exhibits a considerable number under far more
heterogeneous forms. Thus in the types as in the divi-
sions of the classes, the system advances from the older
to the more recent periods; while the more ancient groups
gradually increase and then diminish, as newer, more
perfectly or specifically integrated forms, are interposed.
The former either vanish entirely or outlast the more
recent periods and continue in scanty remnants down to
the present day. The formations mostly have their char-
acteristic organisms, but almost everywhere the connect-
ing links have been exhibited. Everything conduces to
show that it is a question of evolution, not revolution.
80 THE DOCTRINE OF DESCENT.

Wherever there seems to be a sudden break, the case is
the same as in the revolutions of human history, in which
likewise only reforms long-prepared, and practically ne-
cessary, come to a rapid issue.

If we sum up the result of the comparison of fossil
with living animal life, we are first of all struck by the
accordance between the grades succeeding one another
in the order of time, and the members now ranged side by
side in the system. Secondly, when this is confirmed,
the parallelism between the geological succession of ani-
mals and the grades of the individual development of
present animals follows as a matter of course. Agassiz,
in his great work on fossil fishes, pointed out this fact with
irresistible force, and confirmed it by fresh, valuable, and
convincing observations in his later works, down to his
investigations as to the development and growth of
corals. The same examples which served in the preced-
ing chapter to illustrate the parallelism of individual de-
velopment with the systematic stages, may be repeated
here; though many newer and very striking instances
have been brought to light by the special researches of
the last ten years. To express this relation, Agassiz in-
troduced the term “embryonic types,” or “ embryonic
representatives.” Thus the stalked stone lilies are the
embryonic types of the present genus Comatula; -the
most ancient Echinidz are the embryonic representatives
of the higher families of the Clypeastrzee and Spatangide;
the Mastodon, on account of its persistent molar teeth,
is the embryonic type of the elephant, which only transi-
torily possesses such teeth. If the term implies nothing
further than the vague assertion of “the working of the
same creative Mind through all times and upon the whole
SO-CALLED EMBRYONIC AND PROPHETIC TYPES. 81

surface of the globe,” 1 scarcely any solution is obtained.
Let us rather, with Rtitimeyer in his admirable researches
on fossil horses, allow our attention to be drawn by
these and similar facts ‘* to a close connection between
the phases of development in the individual and in the
species,” that is, to a natural connection.

All who absolutely require a personal God in the cur-
rent history of creation, draw from these facts no other
inference than that their God had the whim of producing
at first imperfect and subsequently more and more per-
fect organisms, and of applying in the development of
the last reminiscences of the first.

As worthless as the formula of embryonic types is
another, invented by Agassiz, for the shapes in which,
in some fossil groups, mechanical and physiological re-
sults were imperfectly obtained, and for which provision
is made in later organisms by other more adequate and
perfect arrangements. These are his * prophetic types.”
The Pterodactyl is, for example, supposed to stand in
this relation towards the bird. Does this quibble aid in
the comprehension of either one or the other? Is any
rational idea obtained if, besides the prophecy of the
Pterodactyl, the geologically antecedent insect is regarded
as its prophet, or the bird as the forerunner of the bat?
There is no sense at all unless the prophet becomes
the progenitor, which in these cases cannot be sup-
posed.
82 THE DOCTRINE OF DESCENT.

V.

The Standpoint of the Miraculous and the Investigation of Nature—
Creation or Natural Development—Linnzus—Cuvier—Agassiz—
Examination of the Idea of Species.

“T hear your message well, it cannot wake my faith.
To faith is miracle her dearest child.” *

Havine quoted these words of Faust, we will proceed
without further digression to examine the standpoint oc-
cupied by the Natural Philosopher with regard to a do-
main where the sceptre is wielded, not by the lucid in-
tellect, but by the imagination looking through coloured
glasses; not by Logic, but by arbitrary ideas; where
the laws of causality are turned upside down; a domain
where, indeed, many unquestionably honourable men still
feel themselves at home, but which at best fosters only
pious self-deception, and indolence of mind.

We must take up a decided position without regard
to consequences, as after the discussion of the actual
record of the animal world in its three aspects,
namely, its present tenantry of complete forms, the
evolution of the individuals, and the historical suc-
cession during the earlier periods of the earth’s forma-
tion,—after this superficial work of registration and en-
rolment, the actual study of our subject must begin.

* “ Die Botschaft hér’ich wohl, allein mir fehlt der Glaube.

Das Wunder ist des Glaubens liebstes Kind.”
82
LINNAUS. 83

This is, however, the case only with those to whom the
miracle of creation is absolutely without existence;
whereas an observer, who regards any miracle, however
slight, or any sort of disturbance of the order of nature,
as possible, must deem his science of Biology complete
with the erudition formerly propounded, and subse-
quently extended by countless items of special informa-
tion. We cannot therefore do otherwise than give to
Goethe’s maxim, “ Belief is not the beginning, but the
end of all knowledge,” the interpretation that belief is
incompatible with knowledge, and that hence belief in a
creation of life is incompatible with the investigation
of it.

But if Life did not originate in an incomprehensible
manner, it must have been developed. Many decades
elapsed before this idea with its consequences could be
stated; and in order to comprehend the obstinacy with
which the contrary was maintained, and a circle of opin-
ions allowed to take root, against which modern Biology
alone has waged a successful war, it is necessary to
call to mind some of the chief epochs in the history of
Geology, and their representatives. This will naturally
lead us to the point whence the shaft of knowledge has
been sunk.

After the middle of the last century, Comparative
Anatomy, almost independently of systematic Zoology,
took a prosperous course, and became far richer in ideas
than this descriptive Natural History. One of its max-
ims, however, was accepted without examination—the
constancy and immutability of species; and this maxim
forms the centre of the views entertained by Linnzus.
The continued authority of this great describer of Na-
84 THE DOCTRINE OF DESCENT.

ture, is rendered comprehensible only by the confident
style as well as by the neatness of his diagnoses, by
which, with a single stroke, he put an end to the indefinite
character of Natural History, and appeared to contem-
poraries and posterity as a lawgiver. The exaltation of
species as the basis of all systematic comprehension had
never been so explicitly proclaimed. His opinions cul-
minate in the maxim,?* ‘ Reason teaches that at the
beginning of things, a pair of each particular species was
created.” But with Linnzeus this said reason looks rather
strange, for it is subservient to the strictest scriptural
belief, and he endeavours to harmonize his geological
conceptions with this standpoint.

One very effective geological phenomenon was espe-
cially striking to him, namely, the upheaval of a great
portion of the Scandinavian coast. It proceeds more
rapidly than the subsidence of another part; its phe-
nomena are far mightier; and thus the idea might be
formed that the continent had risen from the sea in regu-
lar progression. ‘‘I believe that I am not straying far
from the truth,” he says, “if I affirm that in the infancy
of the world all the mainland was submerged and cov-
ered by an enormous ocean, save one single island in
this immeasurable sea, on which all animals dwelt and
plants grew luxuriantly.” ©

It follows that all species of plants likewise existed in
this lovely garden, as it is expressly said that Adam
named every animal; consequently all insects must have
been assembled in Paradise, but insects cannot be imag-
ined without plants. Linnaeus then makes the first at-
tempt at animal geography by making the animals dis-
perse themselves from this centre. But the summary
CUVIER. 85

of his idea of species is invariably, “ We reckon as many
species as the Infinite Being created at the beginning.” **
And his authority was so powerful that the age of Vol-
taire and of Diderot devoutly accepted this obvious dog-
ma, and transmitted it to posterity as a maxim impos-
sible to question.

Linnzeus was, however, so little of an anatomist that
in this province Zoology required a completely fresh
foundation, and, in the capacity of a second Linnzeus,
Cuvier stood forth.7 His school styles itself the school
of facts, yet it was by no means without a tincture of
philosophy. On the contrary, -the definite and simple
nature of his principles and deductions could not fail to
be imposing. He epitomized the summary of his ob-
servations as “ Laws of Organization;” and he applied
the teleological view, the principe des causes finales, with
great advantage to the knowledge and restoration of an-
tediluvian animals. The question of the persistency or
mutability of species thrust itself forcibly upon him.
For this an external cause was given by the Egyptian
expedition and the investigation of mummified animals.
Etienne Geoffroy St. Hilaire and Lamarck attacked the
persistency of species, and held that, especially consider-
ing the stability of external conditions, the Egyptian
period was far too short for the identity of the mummies
with the species now extant, to make it possible to infer
the immutability of species; but the question was curtly
despatched and silenced by the predominating school of
Cuvier.

Meanwhile, Cuvier not only increased the accumu-
lation of facts, but, as we have already hinted, he grouped
them so happily and with such philosophical skill that
86 THE DOCTRINE OF DESCENT.

he undoubtedly approached the object at which he aimed
—the Natural System. He supplied the first reliable in-
formation respecting extinct species. With regard to
those which had replaced them in subsequent periods, he
was not, as is generally supposed, an unqualified partizan
of new creations, but he refrained from any fixed opin-
ion. “I will not,” he says,!* “ positively affirm that for
the production of the present animals a new creation
was required. I merely say they did not live in the
same locality, and must have come from elsewhere.”
Geoffroy Saint Hilaire, on the contrary, does not doubt
that the animals now living are descended, by an un-
broken succession of generations, from the extinct races
of the antediluvian age.

Cuvier’s method involved the danger of introducing
dogmatism into natural science, and it is therefore justi-
fiable to refer in this place to one of Cuvier’s immediate
disciples only recently deceased—Louis Agassiz, who in
the most rigidly didactic -manner adheres to the syste-
matic categories, and invests them with fine-sounding
definitions as “ embodied creative ideas.” *® According
to him, species belong to a particular period in the world’s
history, and bear definite relations to the physical condi-
tions predominant at the time, as well as to the contem-
poraneous plants and animals. Species are founded on
well-defined relations of individuals to one another and
the world in which they live, as well as on the proportions
and mutual relations of their parts, and on their orna-
mentation.

Individuals, as representatives of species, bear the
closest relations to one another; they exhibit definite
relations also to the surrounding element, and their ex-
AGASSIZ. 87

istence is limited within a definite period. Of genera
he says, “Genera are groups of animals most closely
connected together, and diverging from one another
neither in the form nor in the composition of their
structure, but simply in the ultimate structural peculiari-
ties of some of their parts.” “ Individuals, as representa-
tives of genera, have a definite and specific ultimate struc-
ture, identical with that of the representatives of other
species.”

We may pronounce these definitions to be mere
phrases, and inquire with Haeckel: “ Of what nature
are these ‘ultimate structural peculiarities of some of
their parts’ which are supposed alone to define the
genus as such, and to be exclusively characteristic of
each genus? We ask every systematizer whether he
may not equally well apply this definition to species,
varieties, &c., and whether it is not finally the ‘ ulti-
mate structural peculiarities of some of their parts’
which produce the characteristic forms of the species,
the variety, &c.” In vain do we search in the “ Essay
on Classification” for a single example of the. manner
in which, for instance, the genera of oxen or antelopes,.
the races of hyzenas and dogs, or the two great genera
of our fresh-water bivalve shells, the Unio and Ano-
donta, are actually distinguished by “the ultimate struc-
tural peculiarities of some of their parts.” Several of
these definitions given by Agassiz may be interchanged
point-blank, so general and merely negative are their
statements. He characterizes the classes “ by the man-
ner in which the plan of the type is executed as far as
ways and means are concerned.” The orders, “by the

degree of complication of the structure of the types.”
7
88 THE DOCTRINE OF DESCENT.

These phrases are interchangeable, but, like all dogma-
tism, they make a great impression on those who from
ignorance of the facts are incapable of criticising for
themselves, and they are readily quoted to confute an
unbelieving investigation of nature by one made in
faith.

It might be thought that if the affair were so simple,
and systematic ideas so firmly fixed, nothing would be
easier than to establish the system. And so Agassiz
maintains. He says that if a single species of any of
the great animal groups were present, and admitted of
investigation, the character of the type, class, family,
genus, and species, might be determined. The weak-
ness of this and similar statements may best be demon-
strated by examining the basis of all dogmatic system,
—the “species.” If this idea be mutable, if the species
be not given once for all, but variable, according to time
and circumstances, the implications of the higher and
more general ideas of genus, family, &c., must neces-
sarily ensue. The keenest and most logical criticism on
the deeply-rooted scholastic idea of “ species” was made
by Haeckel,?° after Darwin, in his classical work on the
“Origin of Species,” had completely exposed the old
doctrine and practice of zoology and botany. In what
follows we shall adhere to Haeckel.

We have seen above that Linnzus accepted the Crea-
tion as an irrevocable scriptural doctrine, and it is really
absurd that many naturalists who have long abandoned
any other dogma, should abide by this one. Therefore
as the Bible mentions the creation of species, this legend
was made the basis of all science. It is true there are
not now many who appeal to scriptural testimony. Those
LINNAZAN DEFINITION OF SPECIES. 89

who defend the stability of species rather imagine that,
with Cuvier, they are entitled to interpret facts in their
own favour; whereas they partly remain unconsciously
involved in hereditary prejudice, and partly contrive to
be deliberately blind to all that evidently contradicts the
immutability of species.

Since Linnzus referred.to the Creation, he attributed
the individuals to a species, of which the pedigree as-
cended in direct line to the pair which proceeded from
the hand of the Creator. Owing to the state of science
in general, an examination of this pedigree was totally
impossible in his time; and, indeed, with the strict reli-
ance on sacred tradition, it was scarcely necessary.
Cuvier, although a very unprejudiced and cool observer,
nevertheless radically accepted the Linnzan definition
of species. According to him, the species is the aggre-
gate of individuals descending from one another and
from common ancestors, and of those who resemble them
as strongly as they resemble one another.”*

“Tn this definition,” says Haeckel, “to which the
majority have ever since more or less closely adhered,
two things are obviously required of an individual as be-
longing to a species: in the first place, a certain degree
of resemblance or approximate similarity of character;
and secondly, a kindred connection by the bond of a
common descent. In the numerous attempts of later au-
thors to complete the definition, the chief stress is laid
sometimes on the genealogical consanguinity of all the
individuals, sometimes on morphological uniformity in
all essential characters. But it may be generally as-
serted that in the practical application of the idea of
species, in the discrimination and nomenclature of the
rele) THE DOCTRINE OF DESCENT.

individual species, the latter criterion alone has almost
always been employed, while the former has been en-
tirely neglected. Later, it is true, the genealogical idea
of the common descent of all individuals of each separate
species was supplemented by the physiological defini-
tion that all the individuals of every species are capable
of producing fertile offspring, by intercrossing, whereas
sexual intercourse between individuals of different species
produces only sterile offspring or none at all. In prac-
tice, however, it was considered quite enough if, among
a number of extremely similar animals under investiga-
tion, uniformity in all essential characters could be estab-
lished, and no inquiry was made whether these individuals
ascribed to the same species were actually of common
origin, and capable, by crossing, of producing fertile off-
spring. The physiological definition was no more ap-
plied in the practical discrimination of animal and
vegetal species, than was the pre-supposed common
descent from a single ancestral pair. On the other hand,
two closely allied forms were distinguished without
scruple as two different ‘good species, whenever in a
number of similar individuals examined a constant dif-
ference could be demonstrated, even though of a merely
subordinate character. Here, again, no pains were taken
to ascertain whether the two different series were not
really descended from common ancestors, and were really
capable of generating in conjunction only sterile hybrids,
if any.”

That this radical condemnation of the post-Linnzan
manufacture of species is not too severe, is shown by
one fact among others; that within the fraternity such
utter discord as to the limitations of species prevailed,
NO ESSENTIAL CHARACTERISTICS OF SPECIES. gl

and still prevails, that no agreement can be arrived at
respecting the basis of the description of species, the
“essential characteristics.” Although Agassiz lays down
the diagnosis of the species, a decision is required in each
case as to the mutual relations of the parts, the orna-
mentation, &c. As in the absence of birds’-nests, snail-
shells, butterflies, &c., it is impossible, when it comes to
the erection of species, to pre-determine what may be
the ‘‘ essential characteristics” of the species they are to
form, subjective opinions and arbitrary decisions have
full play; and within a certain domain, well known by its
forms, there are among the systematizers no two au-
thorities who are agreed as to the number of species into
which the material before them should be divided.

The most unbridled license in the manufacture of
speciés prevailed, however, among the Palzontologists
during a period when, in the endeavour to fix the sub-
divisions of geological strata as accurately as possible by
means of their organic contents, the separation of species
was carried incredibly far, into the most minute and often
into individual deviations. A certain mutability of species
could not fail to obtrude itself on the most purblind eye;
ramifications were made of sub-species, sports of nature,
and varieties characterized by “less essential” peculiari-
ties acquired by means of climate and inheritance.
There was, however, always a reservation that their
crosses with one another and with the main species
should produce fertile offspring, whereas towards other
species their relations were identical with those of the
main species. Of course, in this separation of the
species into sub-species, subjective opinion was even
less fettered by tradition and law than in the definition

t
92 THE DOCTRINE OF DESCENT.

of species. The literature of ornithology during the last
forty years could furnish thousands of the strangest ex-
amples of the Babel-like confusion which was thus intro-
duced.

There is no question that a great, perhaps the greater,
number of organisms now existing are in a condition
in which, according to their internal and external rela-
tions, they may be characterized by Natural History as
so-called species, and for the purpose of recognition and
scientific treatment in general, must needs be so charac-
terized. But this stability, as may be shown both directly
and by analogy, is under all circumstances only tem-
porary, and we have whole classes of organisms to which
it is impossible, even with the widest reservations, to ap-
ply the old idea of species, with its immutability of essen-
tial characteristics. If we are able to furnish incontro-
vertible proofs of the existence of such non-specific
groups, the old system and the dogma of species are once
for all set aside, and the positive basis of a new doctrine
is secured. This evidence is supplied in two directions.
Some classes of organisms in their present state vacillate
and fluctuate in form, in such a manner that it is utterly
impossible to fix the characteristics of species or genus.
They are in an extreme grade of mutability, which, in
others, has given way to an apparent state of repose.
Other series of facts, exhibiting the most obvious muta-
bility of species, are displayed by certain antediluvian
groups in the succession of forms called “ species.”

Even before the appearance of Darwin’s work on the
“Origin of Species,” Carpenter, in the course of his re-
searches on the Foraminifera, arrived at the conclusion,
proved in special instances, that in this group of low
SERIES OF FORMS IN SPONGES. 93

organisms which secrete the most delicate calcareous
shells, there could be no question of “ species,” but only
of “series of forms.” Forms which the systematists
had reduced to different genera and families, he be-
held developing themselves from one another. These
Foraminifera are, however, so simple in structure, the
history of their individual evolution or Ontogenesis is,
as yet, so little known; they contribute so little micro-
scopic detail, which might formulate the law of transmu-
tation of species, that the champions of persistency of
species might still seek refuge in the assertion that
Carpenter’s series of forms are mere varieties, and
only prove that the true “species” have not yet been
found.

We may now turn with advantage to the class of the
Spongiadz, the importance of which in the question of
species I was the first to point out? With them, as I
summed up my researches, it is not as with the Forami-
nifera, merely an affair of the general habit of the form,
of the variable grouping of the chamber systems; but the
variability exists still more specially in the microscopic
detail than in the coarser constituents. In the Forami-
nifera we may speak of microscopic forms, but not prop-
erly of microscopic constituents. But in the sponges
we discern the transformation of the finer morphological
constituents, the rudimentary organs, and we thereby
gain an insight into the mutability of the whole. In this
respect the calcareous sponges are somewhat differently
circumstanced from the rest, and from the silicious
sponges in particular. In the former, the variability of
the microscopic parts is limited to a smaller circle of
forms, whereas the habit of the series of individuals is

ot Ba gece
94 THE DOCTRINE OF DESCENT.

incredibly variable. This variability of the whole body is
not lacking in the silicious sponges; in the genus Tedania,
for instance, established by Gray from some of my earlier
Reniera, we see how their stubbornly coherent needle-like
forms recur from Trieste to Florida and Iceland, under
the most heterogeneous disguises. In some varieties,
however, one of these spicula already manifests a tend-
ency to deviations.

This very point, the possibility of tracing in detail
the metamorphoses of organs, which, on the assumption
of their stability, appeared to provide the system with
the most substantial basis for the erection of genera and
species, renders the investigation peculiarly attractive.
Even among the Algerian sponges, I have adduced
striking examples, and they accumulate in proportion as
the horizon is extended. We arrive gradually at the con-
viction that no reasonable dependence can be placed on
any ‘“‘characteristic;” that with a certain constancy in
microscopic constituents, the outward bodily form, with
its coarser distinctive marks, varies far beyond the limits
of the so-called species and genera; and that, with like
external habits, the internal particles, which we looked
upon as specific, are transformed into others, as it were,
under our hands. ‘‘ Any one ”—thus concludes this sec-
tion of my work on the Fauna of the Atlantic Sponges,—
“who, with regard to sponges, makes his chief business
the manufacture of species and genera, is reduced
ad absurdum, as Haeckel has shown with exquisite irony
in his Prodrome to the Monograph on the Calcareous
Sponges.”

In my specific researches I confined myself essentially
to the silicious sponges, and by thousands of microscopic
NO ABSOLUTE SPECIES EXISTS. 95

observations, by measurements, by drawings, by facts and
inferences, had produced evidence, which acute opponents
of the immutability of species had not brought forward
before me, that in these sponges, species and genera, and
consequently fixed systematic unities in general, had no
existence. The other division of the same class, the cal-
careous sponges, had been treated with unrivalled mas-
tery by Haeckel in his Monograph.?#

He was able not only to confirm my statements, but,
owing to the smaller compass and the greater facility
of observing the group selected for study, to advance
with more sequence and continuity from the observation
of details to the whole, to portray its morphology,
physiology, and evolutionary history with the utmost
completeness. He then challenged the obstructive
party with the assertion that, according to subjective
opinion, either one or 591 species of calcareous sponges
might be accepted, but “that no absolute species exists,
and that species and varieties cannot be sharply sepa-
rated.” Whoever after these demonstrations cleaves to
the phantom of species, without either proving that.the
facts have been falsely observed, or that they may be
interpreted otherwise than in favour of the stability of
species,—whoever, as Agassiz has recently done, ignor-
ing any such researches, publicly asseverates that in no
single case has the mutability of any species been ex-
hibited,—scarcely preserves the right to participate in
the great controversy by which Natural Science is now
perturbed.

There is, however, as we have already mentioned, a
second direction in which the mobility of “ species ” must
be demonstrated, not the direction of breadth, but of
MW 96 THE DOCTRINE OF DESCENT.

height and depth. This mutability of the Spongiade
affords the extremely important evidence that, so to
speak, an entire class has, even now, not attained a
state of comparative repose. But to confirm the mu-
tability of species, evidence of mutability in lapse of
time is justly demanded; the transition of the forms
succeeding one another historically in the strata of the
earth.

In former editions I expressed a belief that a highly
instructive instance of the modification of a species in
time might be seen in the Planorbis from the fresh-
water deposits of Steinheim, described by Hilgendorf.
But this very example has served to warn us how cau-
tious we must be in accepting proofs, since later ob-
servers have sought in vain for the regular succession of
strata that was said to exist, and the series of modified
forms of Planorbis multiformis contained in them; in-
deed, they convinced themselves on the contrary, that
the unusually divergent forms of this snail occur mingled
throughout. However, other evidences of such modifica-
tion abound, and the zeal of some recent Palzontologists
—Waagen, Zittel, Kayser, Neumayr, and Wirtenberger
—has proved, by following up the species, so called, of
Brachiopoda and Ammonitide through vast geological
periods, that it is impossible to arrange these large groups
under true species. I will allow these naturalists to speak
for themselves.

Kayser concludes from an investigation of the
Brachiopoda of the Devonian beds of the Eifel:—‘‘ No
order of animals. perhaps, yields such strong evidence
in favour of the Darwinian theory as the Brachiopoda.
Any one who, like myself, has had occasion to trace a
METAMORPHOSIS OF AMMONITES. 97

great number of these fossils through several strata of
considerable extent and thickness, and to handle hun-
dreds of every species as heretofore classified, must often
have been astonished, to see how wide is the divergence
in many of these species. Often he must have lost all
hope of ever arriving at a clear delimitation of species;
again and again must he have felt less inclined to dis-
miss the idea put forward by Darwin, ‘that our species
are in fact only an artificial concept, a mere formula.’
Kayser consequently finds himself compelled to adopt
purely artificial limits, and speak of ‘ Form-series,’ as
other writers do of Ammonites.” Waagen reminds us
that, long before Darwin, Queenstedt had suggested the
Genetic connection of successive forms in geological
strata, and he then says:—“ There are but few among
the Palzontologists who have recently studied the Am-
monitide under the light of the Theory of Descent, to
whom the facts have not brought conviction. The ex-
istence of Form-series, such as have been shown again
and again by late investigators—series in which each
more recent form deviates but slightly from its pre-
cursor, till the sum total of these small divergences re-
sults in a wide dissimilarity from the original species—
points with coercive clearness to the assumption of
Genetic connection.”

Zittel and Neumayr are of the same mind. Neumayr
writes:—‘ There is hardly any fact which speaks so con-
clusively: for the validity of the Theory of Descent as
the existence of Form-series, which has been proved in
many cases, and of which more instances will certainly
be found now that attention has been directed to the
matter. A peculiarly beautiful example is to be seen—
98 THE DOCTRINE OF DESCENT.

the form here described of Oppelia Darwinii, as a tran-
sition form between the normal type of Pennilobata and
the abnormal semi-forms.” Neumayr confirms many of
Wirtenberger’s most important discoveries, which I will
proceed to quote.

L. Wiirtenberger applied his researches to thousands
of samples from the groups of the Planulate Ammonites
with ribbed shells, and of the Armate Ammonites with
prickly shells. In summing up his results he says,
among other things: “ How among the Ammonites of
the Planulate and Armate groups, the species are to be
branched off from one another, I should be reluctant and
unable to give any instructions, for to me this question
appears utterly hopeless. For in groups of fossil organ-
isms, in which, as in the present case, so many connect-
ing links between the most extreme forms are actually
before us, that the transition is regularly carried on, the
species is far less susceptible of apprehension than in the
organic forms of the present world, which at least denote
the existing limits of the great pedigree of the organic
world. With respect to these fossil forms, it is funda-
mentally indifferent whether a very short, or a somewhat
longer portion of any branch be honoured by a special
name, and looked upon as a species. The prickly Am-
monites, classified under the name of Armata, are so
intrinsically connected, that it becomes an impossibility
to separate the accepted species sharply from one
another The same observation applies also to the
group of which the manifold forms are distinguished by
their ribbed shells, and termed Planulata.” It has further
transpired that the Armata, or Custata, originated from
the Planulata.
SPECIES AND HYBRIDS. 99

We shall return later to Wirtenberger’s preliminary
communications. It was our object here to inform our
readers how and where modern natural inquiry sets aside
the phantom of species, and to enable them to judge for
themselves what series of observations are opposed to
the asseverations that in no single case has evidence been
given of the transition of one species into another. For
the old school falls into the dilemma of proclaiming
whole orders and classes to be “ species,” and the species,
formerly so beautifully defined, to be varieties.

The untenableness of the physiological part of the
definition of species has been conclusively shown first by
Darwin and afterwards by Haeckel. It is known that
even in a state of freedom good species not infrequently
breed together, and that domesticated species such as
the horse and the ass, have been crossed for thousands
of years. But hybrids, the produce of this intercourse,
were supposed to be only exceptionally fertile, and at
any rate not to produce fertile progeny for more than a
few generations. On the other hand, it was considered
certain that the produce of crosses among varieties are
fertile in unbroken succession. The dogma of the
sterility of hybrids was formed without any experimental
or general observation, and by ill-luck was apparently
confirmed by the most ancient and best-known hybridi-
zations of the mule and the hinny. To this familiar ex-
ample, in which the fertility of hybrids proves abortive,
we will oppose only one case of propagation successfully
accomplished in recent times through many generations;
that, namely, of hares and rabbits, two ‘‘ good species ”
never yet regarded as mere varieties.

The numerous and varied forms of the domestic dog
100 THE DOCTRINE OF DESCENT.

were pronounced ex cathedré to be varieties of the same
species, as their crosses are productive. But after read-
ing Darwin’s careful comparison of the reports as to the
relations of certain species of wolves with the dogs of
savage nations, and of the European wolf with the Hun-
garian dog, we must agree with Darwin in thinking it as
extremely probable that in various parts of the world, and
at various periods, wild species of the genus Canis were
domesticated, of which the crosses produce fertile progeny
to an extent almost unlimited.

It is the same with the domestic cat. With the forms
of the European domestic cat, the case is such that it
is scarcely possible to doubt its origin partly from a
Nubian species, and partly from the European wild-cat.
The inferences thus moved in a circle; forms belong
to the same species, because they may be fruitfully
crossed; and because they may be fruitfully crossed,
they belong to the same species; and, on the other hand,
because such and such forms, when crossed, produce no
fertile progeny, they constitute different species; and be-
cause they are different species, they generate no fertile
offspring. The cases of persistent fertility in hybrids are
certainly not frequent, but they are nevertheless so well
certified that the contrary statement is in plain contra-
diction to the facts. But conversely, the proposition that
mongrels, the products of crosses among varieties, are
fertile, thus generally stated, is likewise untenable. The
variety which has been evolved in Paraguay from our
domestic cat, pairs no longer with its ancestral stock, nor
does the tame European guinea-pig with the wild an-
cestral stock of Brazil.

But even if, in general, crosses between varieties are
GEORGE FORSTER. IOI

more easily effected, and more often produce fertile off-
spring than the unquestionably rarer crosses of species,
the frequent failure of crosses between species com-
pletely accords with the modification of species in the
lapse of time, as shown above. Provisionally, let us
hold nothing to be established but that, as to fertility
and the capability of persistent reproduction, the
conditions of mongrels and of hybrids are essentially
similar and different only in degree, and that on these
properties, no closer definition or limitation can be
founded.

If the older definitions of species go back to Paradise,
and derive existent species lineally from ancestral pro-
genitors, miraculously created from the first and never
modified, the ingenuous statements of Linnzeus show that
all this was accepted as self-evident, and that no thought
was given to the proof, which would indeed have been
impossible to obtain. A letter from George Forster to
Peter Camper, dated May 7th, 1787, proves however
that, even in the last century, the voices of more far-
sighted naturalists were raised against this superficial
treatment of the idea of species. Systems, he said, were
founded on this idea, yet everything was uncertain as
long as this expression was not irremovably fixed. But
hitherto all definitions of this word were hypothetical,
and in themselves anything but clear. If we are to ac-
cept as many species as were created, how is a created
species to be distinguished from one produced by the
intermixture of several others? To fall back upon the
Creation is to lose oneself in the Infinite and the Im-
palpable. ‘“ This will never enable us to understand any-
‘thing; and definitions which rest on an inexplicable
102 THE DOCTRINE OF DESCENT.

foundation, on a mystery, ought to be proscribed from
_ science for evermore.” .

Without owning allegiance to any theory whatever,
we are constrained to recognize the fact, that in various
groups of organisms there even now exists such an in-
stability of form, and such a degree of variability, that
it is patent how constrained and artificial is their sys-
tematic separation. In many other groups, in most or-
ders of the Mammalia, for example, this phase of mobility
has been replaced by a certain quiescence, and the forms
now presenting themselves for observation. and com-
parison are so well defined from one another, that
they fit into the system without difficulty as “ good spe-
cies.” But if the ‘‘ good species” are to be judged by
the experiences made in regard to the “bad” ones, and
if the preposterous hypothesis is not laid hold of, in con-
travention to ali healthy human understanding, that
“good species” originated in a miraculous manner in-
accessible to our cognition, whereas the “ bad species ”
are susceptible of analysis,—the other alternative alone
is possible, that, as Haeckel says, if we knew them thor-
oughly, all species without exception would, in the sense
of the species-makers, be “ bad species.” We are also
acquainted with a sufficient number of bad species to be
capable of inferring the general law with certainty.
Nevertheless, all further corroboration and discovery of
bad species is acceptable. Regarded formerly by the
systematists only as incumbrances and as stones rejected
by the builders, they have now become the corner-stones
of science.

Is species therefore, we again inquire, to be entirely
abandoned? Not so, for several reasons. Even assum-
SPECIES ONLY RELATIVELY STABLE. 103

ing that so-called good species, in the sense of the sys-
tematists, have no existence, human intellect, in the en-
deavour to obtain a general view, would be compelled to
denominate the forms, unless all scientific treatment was
to be rendered impracticable. But the retention of spe-
cies is moreover scientifically justifiable and necessary, if
only the determining impulses be taken into account, and
the definition reduced to harmony with reality. Species
is not constituted merely of analogous individuals, for
even the sexes, in the course of development, and without
transformation, diverge considerably from one another.

But if we remember the transmutation of shape tak-
ing place by stages in organisms subject to metamor-
phosis, and the regular sequence of forms alternating with
one another in heterogenesis, we shall be obliged to speak,
not of individuals, but of the cycles of reproduction which
comprise the various phases and series of individuals.
These remain persistent as long as they exist under the
same external conditions. How far time in itself affects
existence and decay is unknown. At any rate, time, as
well as the external conditions of time, is a factor in the
mutation of species. While we regard species as abso-
lutely mutable, and only relatively stable, we will term
it, with Haeckel, “ the sum of all cycles of reproduction
which, under similar conditions of existence, exhibit sim-
ilar forms.”
104, THE DOCTRINE OF DESCENT.

VI.

Natural Philosophy—Goethe—Predestined Transformation according to
Richard Owen—Lamarck.

WE have hitherto confined ourselves essentially to the
contemplation of the phenomena of the animal world as
facts, avoiding as far as possible any examination of the
correlation of these facts, or any criticism of the attempts
to explain them. It was nevertheless necessary to single
out from the history of our science some few impulses of
which the after-effects extend to the present time, and
of which a knowledge is conducive to the comprehension
of prevailing views, tendencies, and prejudices. For this
reason we again revert to the evolutionary history of
Biology and Comparative Anatomy, that we may trace
the present currents to their sources. Since the middle
of last century, there has been no lack of leading ideas
in the organic natural sciences, such, for instance, as are
contained in Buffon’s magnificent project of a picture of
the world. But if it is a question of a single compre-
hensive solution of the organic world, we are at once
reminded of the claims preferred by Natural Philoso-
phy in the first decades of this century, to explain the
tniverse; to derive from the whole, not only matter in”
the abstract, but the being and origin of organic bodies.
When the Philosophy of Identity began to found the
OKEN. 105

laws of the Mind without the study of the body, and in
its own fashion had proved the identity of the corporal
and spiritual world by means of imponderables and non-
organic bodies, their constructions necessarily extended
to organisms.

This attempt to generalize the principles of Schelling
was made by Oken ?? when in his system he conceives
all Nature to be a process of evolution. In his opinion,
natural science is the science of the eternal modification
of God, that is of Mind, in the world, and is thus in the
widest sense, Cosmogony. Everything, when contem-
plated as part of the genetic process of the whole, in-
volves, besides the idea of existence, also that of non-
existence, or position and negation, as it rises into a
higher idea. These contrasts include the category of
polarity, which manifests itself in motion, the life of all
things. The simpler elementary bodies aggregate into
higher forms, which are mere higher powers of the for-
mer, as their causes. Hence the various classes of bodies
‘represent parallel series, each corresponding with and
modifying the order of the other; classes of which the
rational arrangement follows with inherent necessity from
their genetic coherence. But in individuals, these lower
series again become apparent during the period of de-
velopment. The antagonisms in the solar system of the
planets and the sun, repeat themselves in plants and
animals; and as light is the principle of motion, the ani-
mal has the advantage of independent motion, above
the vegetal organism which pre-eminently belongs to the
earth. Embryology receives its due in a general propo-
sition. “ Animals perfect themselves gradually, adding
organ to organ in the self-same manner as the individual
106 THE DOCTRINE OF DESCENT.

animal is perfected.” But in Man, as the highest animal,
the. whole animal world is contained; he is the actual
Microcosm.

If Natural Philosophy be the expression and logical
connection of all well-observed facts, we could not now
designate as Natural Philosophy, Oken’s well-rounded
system, laid down in 3562 propositions, with their in-
ferential conceits of Position, Negation, and Polarity,
the absolutely meaningless formula of -+-o— without
any real penetration of the subject-matter. Various and
important incitements to research were nevertheless sup-
plied by it, and we have been the more anxious to call
attention to this system, as it implies at least as much
as the vague formule and ideas of “intrinsic develop-
ment,” the “ principle of progress,” the “ conversion of
the lower into the higher,” and the whole litany of inde-
cision and indistinctness.

In this chapter we shall not adhere to chronological
succession, but merely characterize various theories of
organic nature; and we may therefore now revert to
Goethe, who in Haeckel’s opinion forestalled his age on
the great question which forms the subject of this book,
and deserves to be honoured as the independent founder
of the theory of descent in Germany.*® We cannot as-
cribe this importance to Goethe, for we must deny the
very cardinal-point on which Haeckel lays most weight,—
that Goethe regards species not merely as modified phe-
nomena of the variable idea of the genus, but as the
sum of bodies modifiable in the concrete. What prin-
cipally induces us to make detailed mention of Goethe
is his penetration of the idea of type, which since the
time of Buffon had been for two generations the lodestar
GOETHE. 107

of a higher research unknown to the pure systematizers.
Goethe elaborated this idea in his own mind on the basis
of a certainly remarkable special knowledge of organic
matter, and undeniably reached the threshold of the solu-
tion. That his scientific activity was a necessary effusion
of his nature, I have demonstrated in the treatises here
cited. Additional evidence has been given by Helmholtz
and Virchow.

Goethe’s notes on his position towards nature, and his
researches, comprise a period of more than fifty years.
About the year 1780, there appears, under the title of
“ Die Natur,” a sort of Hymn to Nature, concluding with
the beautiful words which make him seem a pure
Pantheist: “She placed me in it; she will also lead me
forth; I trust myself to her. She may dispose of me.
She will not hate her work. I spake not of her. No,
whatever is true and whatever is false, she spake it all.
All is her fault, and all is her merit.” And shortly be-
fore his death, in March, 1832, he threw his whole soul
into the scientific controversy as to the different methods
of the investigation of nature and the fundamental prin-
ciples of study, which rose high in the midst of the
French Academy between the two renowned representa-
tives of the inductive and deductive tendencies, Cuvier
and Geoffroy St. Hilaire. What Goethe here laid down
in the evening of his days, is a sort of scientific profes-
sion of faith, and it inspires the greatest admiration to
behold the venerable octogenarian standing on the pin-
nacle of time, and above all parties, with the same prin-
ciples which with his own powers he had framed for
himself five-and-forty years before, in the prime of man-
hood.
108 THE DOCTRINE OF DESCENT.

In the height of his genius, when Goethe, standing at
the centre of the life of Weimar, frequently withdrew
from the bustle of the town and court, he received the
first suggestions of the “ Metamorphosis of Plants.” He
was irresistibly attracted to the varying phenomena of
vegetal life, and he could but muse on the implied unity
and rule underlying this variation. This was a fresh
source of agitation, which pursued him when, in 1787, he
forcibly tore himself from the influences of Weimar and
fled to Italy. There, in Sicily, he found the solution of
the riddle: the leaf seemed to be the rudimentary organ
of vegetal structure. And when, after his return, a new
star rose for him in Christiana Vulpius, he laid down
the quintessence of his ideas on the Metamorphosis of
Plants in that exquisite poem, of which the lines—

‘* All forms have a resemblance, none is the same as another,
And their chorus complete points to a mystical law,
Points to a sacred riddle,—” *

are present to all who ever made themselves acquainted
with the muse of Goethe. He now saw in the various
parts of the plant what he had learnt to see with the
eye of the imagination, which he considers essential to
the Naturalist,—the harmonizing principle. “The same
organ may be expanded into a compound leaf, or con-
tracted into a simple stipule or scale. According to
different circumstances, the self-same organ may be de-
veloped into a peduncle or an unfruitful branch. The
calyx, by over-hastening itself, may become the corolla,
and conversely, the corolla may approximate to the
* Alle Gestalten sind ahnlich, und keine gleichet der andern,

Und so deutet der Chor auf ein geheimes Gesetz,
Atf ein heiliges Rathsel——
GOETHE. 109

calyx. Thus the most varied structures of plants
are rendered possible, and he who in his observations
keeps these laws always before his eyes will derive from
them great alleviation and advantage.” These few lines
contain the pith of the doctrine of the Metamorphosis
of Plants which so greatly agitated his contemporaries
during the first quarter of this century. The many-
sidedness of the idea made it inevitable that the no-
tion, once grasped, should extend to the remainder of
the organic world. Before Goethe, no naturalist had
regarded insects otherwise than as a given sum of indi-
vidual forms, distinguishable by certain definite charac-
teristics. Their internal structure had certainly been dis-
closed by some few great men, such as Malpighi, Swam-
merdam and Lyonet, but a real comparison of species
and genera had never been contemplated; still less an
explanation of the body by its parts. This Goethe ac-
complished, and with true genius; for to his theory,
and with perfect truth, the rings which in the in-
sect are ranged from the head to the tail, presented
themselves, like the vegetal organs, as mere modifica-
tions of one and the same rudimentary organ. There,
the leaf in the abstract, the primordial leaf or plant—
here the ring.

With this—it was in 1796, in the discourses on the
project of a general introduction to Comparative Anat-
omy—he enunciated a truth which was not recognized
till more than forty years later, by one of the most distin-
guished zoologists, Milne Edwards, and applied to the
knowledge of the animal world. This is the idea of the
development of organic beings by the heterogeneous
evolution of their fundamentally similar parts. . Of this
110 THE DOCTRINE OF DESCENT.

the caterpillar and butterfly serve as an example. “ Im-
perfect and evanescent a creature though the butterfly
may be as to its species, when compared to the mammal,
in the metamorphosis which it accomplishes before our
eyes, it nevertheless exhibits the superiority of a more
perfect over a less perfect animal. This consists in the
decisiveness of its parts, the security that none can be
put or taken for the other; that each is destined for its
function, and remains constant to it for. ever.” Now,
however, in the most perfect creatures, the Vertebrata,
there appeared before Goethe’s eye, a similar rudimentary
organ, metamorphosing itself within the individual; this
was the vertebra. He followed it in its transformations
along the vertebral column. Impossible as it may be,
by placing together the first vertebra of the neck with
the last tail bone to infer their identity, it becomes mani-
fest in the gradual transition.

But what lies in front of the first vertebra of the
neck? Is the cranium something absolutely different,
something new, not identical with the vertebral column?
This was another perturbing thought which pursued
Goethe’s every footstep. He pondered and compared;
it could not be otherwise; the cranium must belong to
the vertebral column, must be nothing more than a part
of the vertebral column. Through the vacillations of
his conceptions, he was, as he later expresses himself on
another occasion, “as an honest observer transported into
a sort of frenzy.” Then, when in 1790 he picked
up a bleached sheep’s skull in the Jewish cemetery at
Venice, ‘‘the derivation of the cranium from the verte-
bral bones was revealed to him.” The more special
history of Comparative Anatomy has shown how ex-
GOETHE. III

tremely fruitful was this supposed discovery, although
the subject is far more complex than Goethe and his
followers imagined.

We must commemorate yet another genuine discov-
ery made by Goethe, which exhibits his very peculiar
method. It relates to the inter-maxillary bone in
man. About 1780, he was studying osteology at Jena,
under the guidance of Loder, an anatomist of some re-
nown. It is evident that all higher animals possess a
bone, the so-called inter-maxillary bone, supporting the
upper incisor teeth. “The strange case now oc-
curred,” relates Goethe, “that the distinction between
apes and men was made by ascribing an inter-maxillary
bone to the former, and none to the latter; but as this
part is mainly remarkable as the upper incisor teeth are
set in it, it was inconceivable how man should have the
incisor teeth and lack the bone.” It was inconceivable
to him because, from the comparisons of Nature, he had
framed the idea “ that all divisions of the creature, singly
and collectively, may be found in all animals. To
make man an exception, not to be measured by the
same pattern, was repugnant to his mind. Man must
have an inter-maxillary bone; and, contrary to the
opinions of the greatest anatomists of that period, such
as Peter Camper, he demonstrated how in man this
inter-maxillary bone, although it subsequently becomes
almost undistinguishably anchylosed with the actual
supra-maxillary bone, nevertheless exists, quite dis-
tinctly, as a separate part during development and early
infancy.

From this narrative we have gained a good deal. In
the contemplation of individuals and details, Goethe
112 THE DOCTRINE OF DESCENT.

found no pleasure. Nature and natural objects, as ex-
istent and complete, merely inspired the wish forthwith
to examine their origin and its cause. To judge of
things by their final causes, according to an assumed
purpose pre-determined by Providence, he deemed “a
melancholy expedient ” which must be entirely set aside.
For this method of contemplating Nature, as pursued
by him, in which all living things are to be conceived
as intrinsically connected, the external as an indication
of the internal form, he created the name of Morphology,
the doctrine of form. He examined “ how Nature lives
by creating;” and from amazement at the eternal for-
mation and transformation, from the perplexity into
which he was plunged by the manifold variety of forms,
we see him emerge by seeking and finding primordial
forms.

Even before the realization of the metamorphoses of
plants, we find him surrounded by bones and complete
skeletons in his scientific ossuary at Jena; he thought
he had found a lodestar in the erection of an anatomical
Type, an universal symbol, “in which the forms of all
(vertebrate) animals were potentially contained, and by
which each animal may be described according to a cer-
tain arrangement.” ‘‘ Experience must first teach us
which are the parts common to all animals, and wherein
these parts differ. The idea must control the whole, and
in a genetic manner deduce the universal model.” Thus
by an abstract of the individual, we are to possess
ourselves of a certain archetype. As man could not be
taken as a standard for animals, and conversely, the in-
finite complexity of man could not be fully explained
by animal organization, something fluctuating between
GOETHE. ? 113

the two must be summoned to solve the problem. To
this archetype, itself incapable of representation,—to this
abstraction, and to this alone,—Nature, according to
Goethe, was bound to adhere in her work. of creation,
“without being able, in the slightest measure, to break
through or overleap the circle.”

If it be attempted to make it appear that Goethe
actually proclaimed the doctrine of Descent, or was even
in a poetical sense its inspired prophet, either too much
value is attributed to his enunciations of “ ceaseless pro-
gressive transformation,” and such like, or the sense
which he connected with them is not appreciated. Now
let us take the following passage, which Haeckel looks
upon as decisive. “ Thus much we should have gained;
that we may fearlessly affirm all the more perfect organic
beings, among which we include Fishes, Amphibians,
Birds, Mammals (and at the head of the latter, Man), to
be formed according to an archetype, which merely fluc-
tuates more or less in its very persistent parts, and more-
over, day by day, completes and transforms itself by
means of reproduction.” Is it here meant, perchance,
that the persistent are contrasted with the non-persistent
parts? By no means.

Even prior to Geoffroy Saint Hilaire, Goethe had
spoken of a law, which is, however, no law, nor even an
expression of facts, namely, that Nature in her work has
to deal with a given quantity of material to which she
must adapt it. He does not seem to have been aware
that Aristotle had affirmed the same, that Nature, if
she enlarged an organ, did so only at the expense of
another. A second of the supposed fundamental laws
discovered by: the Frenchman, than organ would sooner
114 THE DOCTRINE OF DESCENT.

perish than resign its place, was likewise instituted by
him at the same time.

Thus, in Goethe’s opinion, nature always makes use
of the same parts. Nature is inexhaustible in the modi-
fication and realization of the archetype; but to that
which has once attained realization cleaves the tenacious
power of persistency, a wis centripeta, of which the pro-
found basis is beyond the influence of anything external.
Hence, if he speaks of daily completion and transforma-
tion by means of reproduction, he understands, with re-
spect to the animal which has attained realization, merely
that course of development or metamorphosis which is
an image of inexhaustible phenomenal nature. The in-
fluences which Nature has exercised upon the parts, he
pictures to himself as still present; but of an actual trans-
formation of existing species into new ones, such as is
required by the modern Darwinian doctrine of Descent,
Goethe does not speak at all.

In his view, what was it, then, that was to be trans-
formed? Surely not the archetype. He says, indeed,
“Thus the eagle fashioned itself by the air for the air,
by the mountain top for the mountain top. The mole
fashions itself to the loose soil, the seal to the water,
the bat to the air;” and generally, “the animal is fash-
ioned by circumstances to circumstances.” But the il-
lustrations which he gives in the Sketch of a.p. 1796,
show plainly that he thought, not of any transforma-
tion of existing forms, but of mere modes of manifesta-
tion of the type and archetype as they exist in given spe-
cies. He then says, “ The serpent stands high in organi-
zation. It has a decided head, with a perfect auxiliary
organ,—a consolidated lower jaw-bone. Only its body
GOETHE. 115

is indefinitely long; and the cause of its being so is that
it expends neither material nor power upon auxiliary or-
gans. As soon as these make their appearance in another
form, as, for instance, in the lizard, though only short
arms and legs are produced, the indefinite length must
at once contract, and a shorter body takes its place. The
long legs of the frog necessitate a very short form for
the body of this creature, and by the same law, the un-
shapely toad is laterally extended.” It is well to bear
in mind this somewhat trivial passage, that we may not
see more in the poetic glorification of the Metamorphosis
of Animals than it really contains.
When Goethe says in the magnificent poem:

“Hence, each form conditions the life and acts of the creature,
And each fashion of life, with reflex forcible action,
Works on the form:” *

it sounds, as we must admit, extremely seductive. But
we are sobered, or rather led to the right standpoint, by
reading his fascinating remarks on d’Alton’s skeletons
of the rodents (1824). It is there made manifest that
Goethe had not the remotest idea of an actual transfor-
mation of a rodent into any other animal by the force of
external influences.

The reader may judge for himself. “ Let us contem-
plate the animal in the neighbourhood of water; as the
so-called water-hog it wallows, pig-like, on the marshy
shore; as a beaver it is seen building by fresh waters;
next, still requiring some degree of moisture, it burrows
in the earth, and at least loves concealment, hiding with

* Also bestimmt die Gestalt die Lebensweise des Thieres,

Und die Weise des Lebens, sie wirkt auf alle Gestalten,
Machtig zurtick——
116 THE DOCTRINE OF DESCENT.

coquettish timidity from man and other animals. Finally.
when the creature arrives at the surface, it hops and
frisks, so that it carries on its existence erect, and even
moves to and fro on two feet with marvellous rapidity.
Transferred to completely dry land, we at last find the
decisive influence of the airy eminence and the all-
vivifying light. The animal is endowed with the greatest
ease of movement; it acts and works with consummate
skill, until a bird-like motion passes into an apparent
flight.”

Thus does Goethe elaborate the influence of environ-
ment and external conditions upon the modifications of
form; it is in vain to look for the actual forms that are
modified. The beaver is not transformed into the mouse-
like burrower, the mouse into the jumping mouse, nor
the jumping mouse into the squirrel, nor does the latter
become a jerboa; but the “ ceaseless progressive trans-
formation” is perceptible only to the eye of the imagi-
nation. In reality, moreover, Goethe sees only adapta-
tion. Greatly as he is inclined to attribute modifications
to the effect of external conditions, he speaks with no
less decision on the contrary side. ‘The parts of the
animal, their relative form, their conditions, their special
characters, determine the requirements of the creatures’
existence;” and if within the restricted circle of forms,
we nevertheless find that infinite modifications of form
become possible (Sketch, 1796), this is only to be de-
duced from the individual species exhibited as modi-
fications of the archetype, by Nature, ever one and ever
creative.

With the word Species, we reach the most important
point in our account of Goethe’s theory of nature; if
.

GOETHE. 117

indeed we have not already unquestionably proved that
he can in no way be regarded as a true precursor of Dar-
win. Darwin and his adherents maintain the variability
of the so-called vegetal and animal species. The ques-
tion is simply whether Goethe was or was not, like his
contemporary Lamarck, convinced of this mutability. If
he says on one occasion that ‘‘ from the seed, plants are
developed, ever diverging and variously determining the
mutual relations of their parts,” this is ambiguous in
itself; it may refer either to the origin of new species,
or to the variability of species by nature immutable.
Another time he speaks of the “ purpose of Nature” in
the horse.

I can find but one single passage in Goethe’s writings
in which there is a question of an actual transformation
of a creature, if not into a new species, at least into a
very marked and persistent variety. In 1820, a Dr.
Korte gave a description of a primeval bull found in
the neighbourhood of Halberstadt, and instituted com-
parisons and reflections, how under the influence of do-
mestication our highly modified cattle had been evolved
from the former. This relic, and another in Thuringia
(1821), which latter specimen was obtained by him for
the museum at Jena, gave him an opportunity of coin-
ciding with Korte, and of illustrating by an actual in-
cident, the possibility of this doubtless easy transforma-
tion.

But from this to the transformation of species there
is still a long way, and Goethe did not traverse it. We
have just seen that the idea of deriving single animals
now existing from extinct.“ ancestral races,” was not un-
familiar to him. Nor would his remark, “ For we have
118 THE DOCTRINE OF DESCENT.

the most distinct remains of organic creatures which were
unable to perpetuate themselves by active reproduction,”
exclude his having accepted generally the immediate
connection, based on direct reproduction, of the animal
world with fossil races entirely differing in struc-
ture. For it is quite true that many species, genera and
groups, passed through, not their prime only, but also
their decline and total extinction antecedent to the
present era.

Yet more. In “ Aphoristic Annotations,” which he
terms problems, written previous to the year 1823, he
speaks of “ characterless races, which it is scarcely per-
missible to assign to a species, as they lose themselves in
boundless varieties,” and he contrasts them “ with races
possessed of a character, which they exhibit afresh in all
their species, so that they may be ascertained in a rational
method.” Goethe rests on this fact to illustrate his idea
of metamorphosis; and we have no right to explain the
characterless or “ disorderly ” races in a Darwinian sense,
as being those of which the forms are not established,
while those which possess a character are divided into
easily distinguishable species, because a host of interme-
diate forms have succumbed in the struggle for existence.
He gave this problem to his intelligent young friend,
Ernst Mayer, that he might work it out, and impart his
reflections to his instructor.

Mayer says: “ The more readily the former (the gen-
era possessing character) are arranged, the more diffi-
cult it is to dispose of the latter (those which possess no
character). But any one who observes them with
earnestness and persevering zeal, and is not totally de-
ficient in intuitive tact, cultivated by exercise, far from
GOETHE. 11g

being perplexed by them, will assuredly, amidst all their
varieties of form, very soon detect the true species and
their characters. But if indeed, in any one genus rich
in forms, no limit to which nature herself adheres should
be discovered, what should hinder us from treating it
as a single species, and all its forms as so many varie-
ties? «As long as the evidence is wanting, which it is
not likely will ever be produced, that no species what-
ever exists in nature, but that every, even the remotest
form, may be evolved from the other by intermediate
links,—till then we-must be allowed to rely upon the
course already indicated. Let the master now instruct
the scholar, or, according to ancient custom, support
him.” And he does support him, for in his morpholog-
ical writings he adopts his pupil’s enunciations on the
problem as a testimony of entire community of mind
and soul.

There can be no question that Goethe’g thoughts on
organic nature were more profound than those of his
contemporaries. But we must not forget that the cardi-
nal idea of a modifiable archetype prevailed among
eminent men both before and with Goethe, as I have
shown in my little work known to the profession, “ The
Development of Comparative Anatomy” (Die Entwick-
elung der vergleichenden Anatomie, 1855). If in his
popular lectures, Peter Camper amused his audience by
a diagram in which he evolved a beautiful female figure
from a horse; if he says that he is so entirely absorbed
in studying the whale and comparing it with the human
structure that every girl, pretty or ugly, appeared to him
like a dolphin or a cachelot; this was because he started
from an archetype or fundamental form. Goethe was only

9
120 THE DOCTRINE OF DESCENT.

more consistent, and notwithstanding the “ painful conse-
quences,” insisted on the inter-maxillary bone in man as
in the ape.

Goethe says in 1807: “If plants and animals be con-
templated in their most imperfect condition, it is scarcely
possible to distinguish them. This much, however, we
may say, that from a kindred so close as scarcely to be

‘discriminated, emerge creatures which, as plants and ani-
mals, are perfected in two different directions, so that the
plant finally attains its glory in the tree, durable and
rigid; the animal in man, in extreme mobility and free-
dom.” But this is nothing more than the repetition, sym-
bolically embellished, in Goethe’s “method of investi-
gating, knowing, and enjoying,” of a proposition already
propounded by Buffon fifty years before, and subse-
quently varied in many ways. |

Nor is it Goethe who, in his Sketch of 1796, first urges
the very suggestive comparison of identical organs in the
same body; this was already done by Vicq d’Azyr in
1786. In a word, the conception of type, archetype,
ground-plan (dessein primitif), was an acquisition of that
age, which was merely expressed by Goethe in a more
pregnant and many-sided manner, and which appears the
more alluring as he combined with it the idea of motion
and mobility, but, owing to his excessive craving for sym-
bols, he did this in a figurative sense.

When Goethe imagines that he has discovered “ laws,”
he labours under the same delusion as that in which
naturalists have rocked themselves from the last century
down to the most recent times, when they accept a mere
corroboration of facts for an explanation of those facts,
for their reduction to their causes. He is acquainted with
RICHARD OWEN. 121

a “ spiral tendency ” and a “ vertical tendency ” in plants,
and they at once become “fundamental laws of life.”
Now in root and stem we undoubtedly see a vertical
tendency downwards and upwards; we see convolutions
and tendrils; we have, moreover, been able to analyze
these facts into simpler physical and physiological phe-
nomena, without having arrived at the innermost cause,
the actual law.

Goethe’s opinion as to man’s place in Nature is im-
plied in what has been already said. That he, a creature
and a product of Nature should form an exception to the
animal so obviously resembling him, he could not ad-
mit. He must remain therefore unconditionally within
the type, “of which the parts are perpetually modified
in all races and species of animals.” But we have now,
I think, furnished sufficient evidence that this and similar
enunciations apply only to the potential variability of the
archetype which has found expression in the races and
species. Hence man also is to him a product allied to
the animal, only by the idea of the type, and not by actual
propagation and descent. This is the solution which he
sought respecting the “most beautiful organization.”
And with this he was content.

From Goethe to our contemporary Richard Owen
seems a wide leap. But if it was our object to produce
in Goethe a stage of natural inquiry which contents
itself with a formula of the correlation of living things,
dazzling indeed, but ultimately vague, the renowned
English comparative anatomist will show us how it is
possible to take even the final step and arrive at the
conclusion that consanguinity is the sole solution of the
similarity of species, and how, nevertheless, by clinging
122 THE DOCTRINE OF DESCENT.

to miracle and dualism, the fruit of the truth just recog-
nized, may be suffered to elude the grasp.”°

By the personal incitement of Cuvier, under whom he
studied in 1830, R. Owen endeavoured to gain a clear
perception of the basis of homologies. If Cuvier had
derived the agreement of organs from teleology by say-
ing that organs are alike because and if they have
like functions to perform, Owen, in Goethe’s fashion,
seized upon an archetype to explain the existence of uni-
formity amid multiplicity and diversity of detail. The
series which repeat themselves in the .organism, such
as the vertebra, and a regular succession in the organ-
isms themselves seemed to him not comprehensible as
miraculous. creations, but only as the result of natural
laws and operating causes, which produce the species in
regular sequence and gradual completion, such laws and
causes being the servant of predetermining intelligent
Will.3+

As a scholar pre-eminently familiar with the fossil
animal world, it could not remain unknown to this Eng-
lish naturalist that the more remote the geological period,
the more general and the less specialized is the organi-
zation of the species. He was able to trace this particu-
larly in the dentition of mammals, and specially also in
the condition of those domestic animals which begin with
the earliest Tertiary times and gradually assume the un-
gulate character. Thus to the question whether species
originate by miracle or by law, he replies that he pre-
sumes the latter to be in constant operation. This
“law” is, however, something quite different from what
science is wont to designate by that name. Why does
the horse exist? Because it was predestined and pre-
LAMARCK. 123

pared for man by the Deity.2? This is supposed to
occur by means of the “ derivative law.” But this again
is a word which conveys no meaning, a phrase which
implies that the horse has become a horse because it
was so to be. The predecessors of the horse modify
themselves for the interest of man, who does not as yet
exist, but is already taken into account by the intelligent
Will.

These ancestors of the horse might therefore be com-
pared to the sports of Nature; the transformation takes
place, not because from inherent reasons it must take
place, but because it so pleases the intelligent Will. We
must beg to decline such “natural laws” as these.
Owen says, “ I deem an innate tendency to deviate from
the parental type, operating through periods of adequate
duration, to be the most probable nature or way. of op-
eration of the secondary law, whereby species have been
derived one from the other.” ** From the Ichthyosaurus
to Man, he sees the connection of descent; he denies that
the influence of circumstances is decisive; he rejects a
dozen times any sort of miracle; but the next moment
he cleaves to miracle again, namely, to an innate tendency
towards a certain future development not imposed by
circumstances and dependent on them, but conducive to
a special purpose.

Thus deal the trimmers, who, through fear of conse-
quences, appease their scientific consciences with a word.

We now come toa courageous writer, whose princi-
pal work, “La Philosophie Zoologique,” ** was over-
looked and well-nigh forgotten for half a century, until it
was restored to merited honour by Darwin, but more
especially by Haeckel, and quite recently in France by
124 THE DOCTRINE OF DESCENT.

Ch. Martins. This is J. B. Lamarck, who first formu-
lated the doctrine of Descent, and in 1804 actually pro-
pounded all the propositions which Darwin has con-
structed afreshandmorecompletely. Lamarck proclaimed
that it is merely our limited powers of comprehension
that demand the erection of systems, whereas all sys-
tematic definitions and gradations are of artificial nature.
We may be assured that nature has produced neither
orders, families, genera, nor immutable species, but
merely individuals which succeed one another, and re-
semble those from whom they descend. But these indi-
viduals belong to infinitely divergent races, which con-
tinue so long as they are unaffected by any cause produc-
ing alteration. Starting from species, like ourselves, he
demonstrates their instability. From comparisons of the
facts of hybridization and the formation of varieties, he
inferred “‘ that all organizations are true productions of
Nature, gradually evolved in the course of a long succes-
sion of ages; that in her progress, Nature began, and
even now always begins again, with the formation of the
simplest organic bodies, and that she directly forms these
only, namely, those lowest living beings which have been
designated as spontaneous generations.”

Variations and transformations supervene, according
to Lamarck, through external influences; in the lapse
of ages they become essential differences; so that, after
many successive generations, individuals which originally
belonged to another species ultimately find themselves
converted into a new one. The limited period of our
existence has accustomed us to a standard of time so
short as to give rise to the vulgar and false hypothesis
of stability and immutability. The transformation is ef-
LAMARCK. 125

fected by the obligation of the individual to accommo-
date itself to the altered conditions of life. Fresh circum-
stances elicit fresh requirements and fresh activities.
Great weight must be laid on the use or disuse of organs.
“In every animal still in the course of development, the
more frequent and sustained use of an organ gradually
fortifies, develops and enlarges it, and endows it with
strength proportional to the duration of this use; while
the persistent disuse of an organ imperceptibly weakens
and deteriorates it, diminishes its efficiency in an in-
creasing ratio, and ultimately destroys it.” “ And thus,”
he says, “nature exhibits living beings merely as indi-
viduals succeeding one another in generations; species
have only a relative stability, and are only transiently im-
mutable.”

Lamarck touches upon the struggle of each again
all (I. 99, and elsewhere), but does not discover the term
Natural Selection. He is fully conscious of the two fac-
tors, heredity and adaptation, but his theories and con-
victions lack the emphasis of detailed evidence. Yet his
subtle apprehension of life may be evinced by his in-
terpretation of instinct. According to him, all acts of
instinct are effected by incitement, exercised upon the
nervous system by acquired inclinations (penchans acquis) ;
and these acts, not being the product of deliberation,
choice, or judgment, certainly and unerringly satisfy the
requirements experienced and the inclinations resulting
from habit. But if these inclinations to maintain the
habit and renew the actions related to them, are once
acquired, they are henceforward transmitted to the indi-
viduals by means of reproduction, which maintains the
structure and the disposition of the parts in the condition
126, THE DOCTRINE OF DESCENT.

attained, so that the same inclination pre-exists in the
young individuals before they put it in practice. This
explanation, as Darwin has shown, certainly does not
’ suffice for all the facts of instinct, yet it stands far above
the modern “ Philosophy of the Unconscious ” (Philoso-
phie des Unbewussten), which places the organisms by
which the instincts are effectuated, under the sway of an
extraneous metaphysical Being who governs it in sub-
servience to design.®5
VII.

Lyell and Modern Geology—Darwin’s Theory of Selection—Beginning
of Life.

Ever since mankind has consciously laboured in the
field of intellect, pre-eminent men have existed, who, rea-
soning more rapidly than their contemporaries, have out-
stripped them in the apprehension of great truths and '
the recognition of important laws. But it is a great
temptation to set too high a value on these anticipations;
and in all cases in which these intellectual exploits are
concerned, it will be discovered that, so to speak, they
floated in the air, and that it was merely a keener scent
and a so-called intuition resting on unconscious infer-
ences, which exalted the privileged being above his less
sharp-sighted neighbours.

Great scientific crises, revolutions in the domain of
intellect, are prepared long beforehand; the watch-word
rarely comes too early and is seldom pronounced in ac-
cents unintelligible to contemporaries; as a rule, if the
change has not been altogether gradual and almost un-
perceived, but if on the contrary the veil has been sud-
denly drawn aside by one of these chosen spirits,
scales fall, as it were, from the eyes of fellow-labourers

and spectators, and the rapidity with which the new theory
127
128 THE DOCTRINE OF DESCENT.

makes its way affords the best evidence that it took shape
and was proclaimed at the proper moment.

That the doctrine of Descent was likewise no utterly
startling apparition, even though it leapt forth from the
head of Darwin, its greatest representative, like an armed
Minerva—of this we have cited at least a few of the many
vouchers. That its time had come,—that it was indeed
more than time, unless the science of the nature of life,
and Biology in general, was to be unduly backward,—
1s shown by the development of Geology, which thirty
years prior to Darwin, after many favourable forecasts,
struck upon the right road to the knowledge of causes.
The doctrine of the formation and evolution of the earth,
especially in its earlier phases, during which Life, in the
sense generally attached to the word, originated and be-
came permanent on our Planet,—this science of Geology
is intimately allied with our important theme. Modern
Geology, especially as connected with the name of Charles
Lyell, must sooner or later have necessitated an analo-
gous treatment of vegetal and animal lore, and we can
only wonder that the crisis was so long delayed. The
exposition of the doctrine of Descent must, therefore, be
introduced and initiated by a reference, however brief, to
modern Geology.

The first edition of Lyell’s ‘ Principles of Geology’
appeared in 1830. The tenth, published in 1866, gave
him an opportunity of professing his full adhesion to the
Darwinian doctrines, to the development of which he
had given so great an impulse. Since 1872, the eleventh
edition of this masterpiece has been before the world.
It treats of the investigation of the lasting effects of
causes now in operation, as data from which inferences

?
LYELL AND RECENT GEOLOGY. 129

as to past ages may be drawn. Lyell termed these ef-
fects an autobiography of the earth. “ The forces now
operating upon earth are the same in kind and degree as
those which in the remotest times produced geological -
changes.”

Probably, in consequence of the havoc caused by local
floods and earthquakes, a belief in great and universal
catastrophes was formed at a very early period; and to
the Indian and Egyptian legends on this subject Lyell
appends the remark, that the traditional connection of
such catastrophes with a belief in repeated and universal
corruption of morals may be easily explained.

At the end of the last century, the opinion was here
and there expressed that the submergence of large ex-
tents of land, and the emergence of others, had taken
place slowly; and the doctrine was in preparation that
the mineral masses fall into various groups, succeeding
one another in definite order. Werner then appeared
and founded the special science of ‘“ Geognosy.” He
was not the first to see and teach the regular succession
of rocks, but the sensation which he caused was uni-
versal. From his time dates the violent controversy of
the Vulcanists and Neptunists, and into the midst of this
controversy fell Cuvier’s great discoveries on the animals
of the Tertiary formation in the vicinity of Paris. By
the works of Cuvier and Lamarck on fossil animals, the
differences betwixt ancient and modern organisms be-
came apparent, and Cuvier’s views, zoological as well as
geological, gained the victory. The conviction was grad-
ually established that long ages of repose and quiescence
alternated on earth with shorter periods of universal catas-
trophes and revolutions.**
130 THE DOCTRINE OF DESCENT.

Even after the appearance of Lyell’s “ Principles of
Geology,” the hypothesis of catastrophes received its
special completion by Elie de Beaumont’s theory of the
structure and genesis of mountain chains. From the
first, however, Lyell interposed, and derived the following
conclusion from a comparison of the slow but continued
and perceptible upheavals and subsidences occurring in
historic times, with the various modifications which or-
ganisms had meanwhile undergone. “In a word, the
movement of the inorganic world is obvious and palp-
able, and might be likened to the minute-hand of a
clock, the progress of which can be seen and heard;
whereas the fluctuations of the living creation are
nearly invisible, and resemble the motion of the hour-
hand of a time-piece. It is only by watching it atten-
tively for some time, and comparing its relative position
after an interval, that we can prove the reality of its
motion.” :

Careful observation and logical deduction had thus
arrived at conclusions diametrically opposite to the as-
sertions of Cuvier, who inferred the geological catas-
trophes mainly from the striking difference of successive
organisms. While botanists and zoologists prosecuted
their studies on Cuvier’s system, Geology was being
metamorphosed under the hands of Lyell and his ad-
herents. He proceeded from the most tangible basis.
That it rained during the era of the coal formation, as
it now rains, may be seen by the impress of rain-drops
on the levels of that formation. The actions of rivers,
the sediments of deltas, previously neglected, were now
studied, and likewise the colossal mud deposits, such as
are exhibited by the Nile and the Amazon, and also the
DARWIN. 131

destructive work of the irregular motions of the sea, and
the partly destructive, partly formative work of its regu-
lar currents. Calculations were made of the ploughing,
grating, and grinding of glaciers, of the substances
which mineral springs dissolve and deposit, of the dis-
placements of material effected by existing agencies, of
the manner in which the outlines of land and sea are
altered by elevation and subsidence. Similarly, the
comparison of ancient and modern coral reefs and
oyster banks showed that these silent builders have not
changed their habits. In short, the hypothesis of ex-
traordinary events and forces, unheard of in our present
era, seemed quite unnecessary; time only, and the con-
tinuous development of the earth’s crust, were rendered
evident.

The stage for reiterated acts of new creation of organ-
isms had thus collapsed, and the hypothesis of such
miraculous new creations became an anachronism, for
which a well-merited end was inevitably prepared by the
appearance of Darwin. With Darwinism, the doctrine
of Descent is an historical necessity.

.Charles Darwin was born in 1809, and, as the Natu-
ralist attached to the Beagle in her voyage round the
world, under Captain Fitzroy, in 1831-7, he enjoyed an
opportunity of accumulating rich experiences. His im-
portant work on Coral Reefs gave the first adequate ex-
planation of the phenomena resulting from the co-
operation of geological movements, and the organic
agency of the coral animal; his Monograph on Cirripedes
bears witness to the exemplary care with which he can
observe and systematically work out the relations of the
minutest details. We make this remark, as the op-
132 THE DOCTRINE OF DESCENT.

ponents of the great inquirer endeavour to suppress his
merits and authority by maintaining that he is properly
a mere dilettante, dealing with general abstractions,** a
stranger to the keen observation which takes full ac-
count of facts. How Darwin arrived at the idea which
has made an epoch in science, he has himself made
known in the introduction to his first work on the doc-
trine of Descent, namely, the “ Origin of Species; ” ** and
in more detail in a letter to Haeckel, publishéd by the
latter in his “ History of Creation” (Natiirlichen Schdp-
fungsgeschichte).

“ Having reflected much on the foregoing facts, it
seemed to me probable that allied species were descended
from a common ancestor. But during several years I
could not conceive how each form could have been modi-
fied so as to become admirably adapted to its place in
nature. I began, therefore, to study domesticated ani-
mals and cultivated plants, and after a time perceived
that man’s power of selecting and breeding from cer-
tain individuals was the most powerful of all means in
the production of new races. Having attended to the
habits of animals and their relations to the surround-
ing conditions, I was able to realize the severe strug-
gle for existence to which all organisms are subjected;
and my geological observations had allowed me to ap-
preciate to a certain extent the duration of past geolog-
ical periods. With my mind thus prepared I fortunately
happened to read Malthus’s ‘Essay on Population;’
and the idea of natural selection through the strug-
gle for existence at once occurred to me. Of all
the subordinate points in the theory, the last which I
understood was the cause of the tendency in the de-
ARTIFICIAL SELECTION. 133

scendants from a common progenitor to diverge in char-
acter.” *

That organisms are variable and not fixed in rigid
forms, is a phenomenon so general that variability passes
current as a self-evident property of organic existence.
In the next chapter we shall inquire how far everything
organic is necessarily subject to mutability. On the ex-
istence of this property rests the artificial breeding, or
selection by man, consciously and unconsciously exer-
cised from the earliest commencement of hunting and
agriculture, of which, as Darwin says, " the importance
mainly lies in the power of selecting scarcely appreciable
differences, which are nevertheless found to be trans-
missible, and which can be accumulated until the result
is made manifest to the eye of every beholder.” In the
“ Origin of Species,” as an example of methodic selection
in the production of breeds, Darwin has chosen the
pigeon, to the breeding of which he zealously devoted
himself for many years.

The pigeon is specially adapted to the purpose of
scientific observation of the phenomena of breeding, be-
cause, owing to its monogamic habits, it is easy to control,
because it may be brought in a short time to striking
variations, because the records of its breeding are tol-
erably complete, and, finally, because it is one of the few
domestic animals of which the ancestral stock is scarcely
open to a doubt.

The chief races produced by: the fanciers may be
grouped as follows. The Pouter Pigeons*have a mod-
erate beak, elongated legs and body, their cesophagus

* Mr. Darwin has himself been good enough to re-write his letter from
the German text. He kept no copy of the original MS. '
134 THE DOCTRINE OF DESCENT.

is of great size, barely separated from the crop, and is
capable of inflation. A second group includes Carriers,
Runts, and Barbs, which possess in common a long beak,
with the skin over the nostrils swollen and often carun-
culated or wattled, and the skin round the eyes bare and
likewise carunculated. To another group, with shorter
beak, and the skin round the eyes only slightly devel-
oped, belongs the Fantail, in which the normal number
of twelve tail feathers may rise to forty-two with aborted
oil-gland; also the Tumbler, in which the beak becomes
extremely short, and a sickly disposition of the brain,
produced and exaggerated by selection, and manifesting
itself by tumbling, has been transmitted for more than
250 years, and has become established as the character-
istic of a race. In the fourth group, the Trumpeter oc-
cupies a prominent position, on account of its peculiar
voice; likewise the Laugher, or Indian turtle-dove, com-
prising several sub-races scarcely differing in structure
from the rock-pigeon (Columba livia). The latter is di-
vided into several geographically distinct races, ranging
from the coasts of the Faroe Islands and Scotland to
the shores of the Mediterranean and to India; and the
most minute investigation, whether the incredibly di-
vergent races of domestic pigeons are derived from eight
or nine wild species or solely from the wide-spread rock
pigeon, results decidedly in favour of the latter alterna-
tive. Proportional dimensions, colouring, and parts of
the skeletons which differ from one another far more
widely in the various races than they do in well marked
species of the same genus, or even family, are modified
under the hand and according to the will of man; and,
moreover, pre-eminently in the pigeon may be traced
ARTIFICIAL SELECTION. 135

“6

the phenomenon which has been termed the “ correla-
tion of growth,” and consists in the fact that, with the
intentional modification of an organ by means of selec-
tion, one or more other organs are drawn into sympathy
and unintentionally transformed into characteristics of
a race.

Darwin’s minute researches on the formation of races
in the pigeon are recounted in his second work on the
theory of Descent, “ The Variation of Animals and Plants
under Domestication,” in which the most detailed investi-
gations respecting other domestic animals are also to be
found. Whoever has had occasion to inspect one of the
modern exhibitions of poultry, must have been astonished
at the diversity of the different races, and the purity and
uniformity within each race. Though not quite so posi-
tively as in the case of the pigeon, yet with approximate
certainty, the domestic fowl appears to be derived from
a single ancestral stock, the Indian Gallus Bankiva. The
cumulative power of selection by man is likewise testified
by the various races of pigs bred within the last century
by the English farmers from an intermixture of the na-
tive and Indian races, differing in general appearance,
colouring, size of ears, length of legs, and also partially
in fertility. Our attention is, however, more closely
drawn to the two races of Southdown sheep and Short-
horn cattle, which, as well as the choicest breeds of pigs,
have been for some years past particularly esteemed on
the continent. These and many other races have been
bred with definite purposes, and for certain domestic and
commercial advantages, and one and all bear testimony
to the plasticity of species.

Artificial selection operates by establishing peculiari-
Io
136 THE DOCTRINE OF DESCENT.

ties originally variable, and on their first accidental ap-
pearance usually perceived only by the careful eye of a
connoisseur. But not a few cases are likewise certified
in which an accidental deformity and a new character
appearing suddenly even in a single individual have lent
themselves to the rapid formation of a race. “ Thus,”
as Darwin relates,* ‘in 1791 a ram lamb was born in
Massachusetts, having short, crooked legs and a long
back like a turnspit dog. From this one lamb the otter
or ancon semi-monstrous breed was raised; as these
sheep could not leap over the fences, it was thought that
they would be valuable; but they have been supplanted
by merinos, and thus exterminated. These sheep are
remarkable from transmitting their character so truly,
that Colonel Humphreys never heard of but one ques-
tionable case of an ancon ram and ewe not producing
ancon offspring.” A more interesting case has been
recorded in the Report of the Juries for the Great Exhi-
bition (1851), namely, production of a merino ram lamb
on the Mauchamp farm in 1828, which was remarkable
for its long, smooth, straight, and silky wool. By the
year 1833, Mr. Graux had raised rams enough to serve
his whole flock, and after a few years more he was able
to sell stock of his new breed. So peculiar and valu-
able is the wool, that it sells at 25 per cent. above the
best merino wool; even the fleeces of half-bred animals
are valuable, and are known in France as the Mauchamp
merino. It is interesting, as showing how generally any
marked deviation of structure is accompanied by other
deviations, that the first ram and his offspring were of
small size with large heads, long necks, narrow chests,
and long flanks; but these blemishes were removed by
UNCONSCIOUS SELECTION. 137

judicious crosses and selection. The long, smooth wool
was also correlated with smooth horns; and as horns
and hair are homologous structures, we can understand
the meaning of this correlation. If the Mauchamp and
the ancon breeds had originated a century or two ago,
we should have had no record of their birth, and many
a naturalist would, no doubt, have insisted, especially
in the case of the Mauchamp race, that they had each
descended from or been crossed with some unknown
aboriginal form.”

If with the refined culture of races on large estates,
we compare the slight attention bestowed on domestic
animals in small peasant farms, remote from the cheering
intercourse of the world, and then descend to the treat-
ment by savages of their few domestic animals, or their
sole tame creature, the dog, conscious artificial selection
gradually decreases; but wherever man attaches to his
abode either plants or animals, selection is at least un-
consciously exercised. The powerful animal, the particu-
lar plant which yields the most abundant nutriment,
are employed. for propagation without any special fore-
thought, and unconscious selection is thus undistinguish-
able from that which is methodically practised. The
initiation and progress of the production of races is
naturally facilitated by the power of placing the animals
selected for breeding, in a new environment and fresh
conditions of life, and the formation of new races is fa-
voured by the ease with which it is possible to hinder
the crossing of forms in course of construction, with races
already existing.

Unquestionably many races of domestic animals are
not in a condition in which they can be termed new
138 THE DOCTRINE OF DESCENT.

species; that is to say, in regard to the new characters
evolved by breeding, they are in a state of merely artificial
stability; and, if abandoned to accidental or irregular in-
termixture with the aboriginal or other races, they gradu-
ally revert to their primitive form. But it is arbitrary and
erroneous to assert that all unconsciously or consciously
bred races, without exception, are no new species, and
would all relapse if left to a state of nature.

Granting that all the races of fowls were left to them-
selves, we must certainly admit the possibility that in
India some few forms would change back into the Ban-
kiva fowl. It is, however, evident that, in Europe and
America, from any semi-feral races of fowls the aborig-
inal Indian race would never reappear, but at the most
some few new wide-spread mongrel forms would arise,
remaining constant according to geographical districts.
No one has yet been able to assert that the wild dogs of
the East, entirely released from the control of man, have
become wolves or jackals, their presumptive ancestors.
They become “ jackal-like,” by which every one expresses
that the dog which became and was bred a domestic ani-
mal thousands of years ago, preserves its acquired spe-
cific characteristics even under circumstances most fa-
vourable to their destruction.

This statement, that domestic animals are no new
species, is the more unfounded, as of several domestic
animals the aboriginal stock is totally unknown; among
these are the sheep and goat, respecting the ancestors
of which only vague conjectures can be framed. The
most ancient race of sheep known to us,—that with.ram-
like horns, found among the lake dwellings of Switzer-
land, throws no light upon the subject; and empirically
NATURAL SELECTION. 139

to observe the reversion of the modern sheep to its
aboriginal form is utterly impossible. That the horse
is derived from a striped aboriginal species is probable;
but notwithstanding the many generations during which
the great herds of feral horses in South America have
propagated themselves undisturbed, no such species has
been produced. Rtitimeyer’s minute researches on do-
mestic cattle have shown that, in Europe at least, three
well-defined species of the Diluvial period have contrib-
uted to their formation, Bos primigenius, longifrons, and
frontosus. These species once lived geographically
separate, but contemporaneously; and they and their
specific peculiarities have perished, to rise again in our
domestic races. These races breed together with un-
qualified fertility; in the form of skull and horns
they recall one or other of the extinct species; but
collectively they constitute a new main species. That
from their various breeds, the three or any one of
the aboriginal species would ever emerge in a state
of pristine purity, would be an utterly ludicrous as-
sertion.

In all these domestic animals—dog, sheep, goat, horse,
and cattle—the transformation was initiated in an era of
civilization in which there was no idea of artificial breed-
ing in the modern sense, and in which the main factor of
transformation, independently of involuntary and uncon-
scious selection, consisted simply in the altered mode
of life. This introduces us to variations in a state of
nature, and to Natural Selection. Natural as well as
artificial selection both rest on the undisputed fact of the
idiosyncrasies of the most closely allied vegetal and ani-
mal individuals; and it has already become manifest
140 THE DOCTRINE OF DESCENT.

that doubtful species are not exceptional, as the old school
was wont to imagine, but that it is merely owing to an
inadequate knowledge of the material out of which species
are constructed, that all species are not looked upon as
doubtful and artificial.

Let us here again call to mind that in many thousand
cases the most rigid systematizers are unable to state
where their species begin and end; of which Darwin,
as an instance, cites a communication by H. C. Watson,
that 182 British plants, usually regarded as varieties, have
each been claimed as independent species by individual
botanists.‘ Darwin’s immortal service consists in hav-
ing shown what is the power which operates upon the
existing variable individuals and species, and what re-
sults this operation must produce. He found the key
in the word which has become a badge and common
property of our age, “the struggle for life,” * and has
thus given the foundation and theory of a doctrine of
which the truth had long before been manifest to an in-
tellect such as that of Lamarck. He founded the doc-
trine of Descent on the theory of selection, when he
proved that in nature the struggle for existence occa-
sions a selection of the best and fittest, comparable
to artificial breeding, and giving rise to new races and
new species.

The struggle for life, this bellum omnium contra omnes,
is, moreover, an undisputed and undeniable fact, which
we here accept in its widest relations. Not only does
the beast of prey war against the graminivorous animals,
which again strive to keep their balance by superior mul-
tiplication, speed, and cunning; the gradual advance of

* For Wallace's share in this honour, see the end of this chapter.
THE STRUGGLE FOR EXISTENCE. 14

a plant is likewise a struggle with natural obstacles; and
the conquest which it gains usually injures other plants
in their conditions of life. If the powers of multiplica-
tion of any given organism were to operate absolutely
and unrestrictedly, each being would, in a short series
of years, claim for itself the whole surface of the earth,
or all the waters of the sea. But each holds the other
in check; and with the living foes of each creature are
associated the climate and all the influences of the sur-
rounding conditions, and of the alternation of the sea-
sons, to which the body must accommodate itself. Or-
ganisms live only at the cost of, and for the profit of,
others; and the peace and quiet of nature sung by the
poet is resolved under the searching eye into an eternal
disquiet-and haste to assert and maintain existence, amid
which it is only the thought of the visible and necessary
progress that can rescue the observer from a pessimist
view of the world.

The simplest examples of the relations of mutual de-
pendence of living beings are, however, the best and most
conclusive; but the vast consequences depending on cir-
cumstances and connections apparently insignificant, and
the extreme complexity of the mechanism by which equi-
librium is maintained, have been exhibited by Darwin
in some examples, which, frequently as they have been
repeated, we shall also allow ourselves to reproduce.
Whereas, to the South and North of Paraguay feral cattle,
horses, and dogs abound in profusion, they are wanting
in Paraguay itself. ‘“ Azara and Rengger have shown
that this is caused by the greater number in Paraguay of
a certain fly, which lays its eggs in the navels of these
animals when first born. The increase of these flies, nu-
142 THE DOCTRINE OF DESCENT.

merous as they are, must be habitually checked by some
means, probably by other parasitic insects. Hence if
certain insectivorous birds were to decrease in Paraguay,
‘the parasitic insects would probably increase, and this
would lessen the number of the navel-frequenting flies;
then cattle and horses would become feral, and this would
certainly greatly alter (as indeed I have observed in parts
of South America) the vegetation, and this, again, would
largely affect the insects, and this the insectivorous
birds, and so on, in ever-increasing circles of com-

plexity.”
Another example out of Darwin’s store is perhaps
even more striking. “I find from experiments that hum-

ble-bees are almost indispensable to the fertilization of
the heartsease (Viola tricolor), for other bees do not visit
this flower. I have also found that the visits of bees are
necessary for the fertilization of some kinds of clover;
for instance, 20 heads of Dutch clover (Trifolium repens)
yielded 2,290 seeds, but 20 other heads, protected from
bees, produced not one. Again, 100 heads of red clover
(T. pratense) produced 2,700 seeds, but the same number
of protected heads produced not a single seed. Humble-
bees alone visit red clover, as other bees cannot reach
the nectar. It has been suggested that moths may fer-
tilize the clovers; but I doubt whether they could do so
in the case of the red clover, from their weight not being
sufficient to depress the wing-petals. Hence we may
infer as highly probable that, if the whole genus of hum-
ble-bees became extinct or very rare in England, the
heartsease and red clover would become very rare or
wholly disappear. The number of humble-bees in any
district depends in a great degree on the number of field-
THE STRUGGLE FOR EXISTENCE. 143

mice, which destroy their combs and nests; and Colonel
Newman, who has long attended to the habits of humble-
bees, believes that more than two-thirds of them are thus
destroyed all over England. Now, the number of mice
is largely dependent, as every one knows, on the number
of cats; and Colonel Newman says, ‘ Near villages and
small towns I have found the nests of humble-bees more
numerous than elsewhere, which I attribute to the num-
ber of cats that destroy the mice. Hence it is quite
credible that the presence of a feline animal in large num-
bers in a district might determine, through the interven-
tion first of mice and then of bees, the frequency of cer-
tain flowers in that district.’ ”

The closer the kindred of the competitors, the more
ardent is the struggle for the existence; for the more
adjacent organisms differ in their requirements, the less
do they interfere with one another, and the more will
each be able to exhaust the resources of the vicinity for
its own benefit. This seems to be flatly contradicted by
the great series of associated plants and animals; but
on closer inspection they also form no exception to the
rule, as, often by their very number they render existence
possible and easy to one another, and increase exactly
in the degree permitted by the stock of nutriment. If
among associated plants or gregarious animals a surplus
production occurs, competition and conflict instantly
commence, and life is regulated in every respect ex-
actly as in species less remarkable for the number of indi-
viduals.

Our proposition that the vehemence of the struggle
rises with the closeness of the kindred, is thus univer-
sally valid. Such a rapid war of extermination is rarely
144 THE DOCTRINE OF DESCENT.

waged as that between the black rat (Mus rattus) and
the brown rat (Mus decumanus); and we far more fre-
quently imagine that harmonious intercourse exists be-
tween the members of the same species sharing the
same habitation, as, for instance, hares or deer, than
that they are anxiously striving to maintain existence.
Yet this is not the case. The two great motive powers,
the preservation of the individual and the preservation
of the species, are unremitting instigations to warfare,
and under their influence every living being, plants in-
clusive, joins in conflict with its congeners of the imme-
diate vicinity.

In this competition for nutriment, combined with de-
fence against all possible enemies and other rivals for the
remaining privileges of existence, the strongest gains the
advantage, or the most crafty, the most skilful—in short,
the one that can measure itself against its rivals armed
with any sort of superiority. Not only in the struggle
for mates, but on every occasion of competition, the
weaker individuals are beaten off, and a selection of the
strongest andthe best takes place. But the primarily
slight,—often scarcely perceptible, advantages, mental as
well as bodily, which aided these individuals to conquer
and survive the other members of the species who were
weaker and destitute of accidental advantages, have a
prospect of being transmitted, and in the following gen-
erations of becoming established and increased by re-
peated selection. This selection is therefore a natural
and necessary course of things; and it applies, not in
a merely general and vague manner, as in the external
habit, size, and strength of the individual, but, owing
to the actual variability and plasticity of the organic
SEXUAL SELECTION. 145

morphological constituents, single parts and organs may
be modified and perfected in definite advantageous direc-
tions, so as to secure for the race and species a higher
position in the surrounding world.

Besides the general results of the right of the strong-
est, another very influential phenomenon comes into play
where the desire for propagation is concerned, which Dar-
win has designated as ‘“‘ sexual selection,” and elaborated
in great detail in his work on the ‘‘ Descent of Man.”
In this we must consider, first, the formation of sexual
peculiarities in the males, and the secondary char-
acters by which they are aided in the courtship of the
females; and only secondly the reactions of these pe-
culiarities on the alteration and progress of the species in
general.

The fundamental idea of Darwin’s theory of selection
is-therefore, that the cumulative power of selection ex-
ercised by man in the breeding of races, is, in nature,
replaced by the struggle for life; and that in the course
of time, by the cumulation of advantages primarily
slight and becoming more and more prominent, lower
organisms are converted into higher ones. The process
is incessant. “It may be metaphorically said, that
natural selection is daily and hourly scrutinizing through-
out the world the slightest variations, rejecting those that
are bad, preserving and adding up all that are good;
silently and insensibly working, whenever and wherever
opportunity offers, at the improvement of each organic
being in relation to its organic and inorganic conditions
of life.” *# :

The following chapters will introduce us more nearly
to this theory, its truth, possibility, application, and con-
146 THE DOCTRINE OF DESCENT.

firmation; meanwhile we will at once make ourselves ac-
quainted with some of the objections offered to it, either
to the theory of selection in particular, or to the theory
of selection combined with the doctrine of transformation
as a whole; the most important of which Darwin has al-
ready considered and answered.

If, so it is said, all living beings stand in distinct and
uninterrupted connection with one another, what has be-
come of the infinitely numerous intermediate forms which
must necessarily have existed? Our eyes turn first to
the organisms now living, and as, in accordance with
the theory, they are assumed to be the terminal twigs
of an infinitely ramified tree, which must obviously
press hard upon one another, and must each inde-
pendently diverge in all directions as varieties, we ask
for the intermediate forms of the species now existing
side by side.

We may now appeal to the evidence already given
(p. 92, &c.), that in complete and extensive groups of or-
ganisms, modern scientific research has been able to dis-
cern nothing else than intermediate forms. Similarly,
the journey undertaken by Kerner in his little book on
“Good and Bad Species,” in company with the botanist
Simplicius, from the West of Europe to the East, will
furnish an amusing number to the reader eager for
further material. The extension of the various species
of Cytisus which this naturalist has minutely investigated,
likewise exhibits the uninterrupted existence of connect-
ing forms on the territorial boundaries of species of which
the centres of propagation are more or less remote.
From all these instances, which may be reckoned by
thousands, it may be inferred that a large proportion are
DEFICIENCY OF TRANSITIONAL FORMS. 147

in a phase of relative stability. That for this reason their
intermediate forms must be looked only for in the past,
is as little surprising; it in no way impugns the truth of
the doctrine of Descent; and the demand for intermedi-
ate forms between these local and temporarily stable
forms merely proves how little those who make it have
appreciated the nature of Descent.

But the objection mainly concerns those intermediate
forms by which the species are connected with the
aboriginal species preceding them in order of time.
According to the theory, the species now living are con-
nected with the aboriginal species by forms identical
in quality with varieties, the “species in process of
formation;” the aboriginal species with others still
more ancient, and so on; so that an infinite number
of forms must have existed. We have already shown
(p. 97, &c.) that in an excess of zeal paleontologists have
set up species, also to be reckoned by thousands, where
merely transitional forms and varieties actually existed;
we have mentioned that a number of distinguished
paleontologists of the present day are endeavouring to
remedy the errors of their predecessors, and to exhibit
the uninterrupted transitional series from the lower to
the more recent strata, where the others with lavish in-
genuity imagined they had discerned specific characters.
Still it must be admitted that the amount of transitional
forms as yet actually found are a vanishing quantity,
as compared with the countless multitude which must
have existed.

But this deficiency may be satisfactorily explained.
We know only a very small proportion of the fossiliferous
strata, and, with as much justice as Lamarck in the be-
148 THE DOCTRINE OF DESCENT.

ginning of this century, we may point even now to the
poverty of the collections. Wherever the palzontologist
now lays his hand he finds intermediate forms, and day
by day the material accumulates as it is required. Never-
theless, too much is demanded, and the conditions of
preservation are misunderstood, if it be supposed that
all intermediate forms that ever existed were, by their
bodily constitution, either wholly or partially adapted to
preservation, and must therefore have been actually pre-
served. On the contrary, the greater number have as-
suredly vanished without a trace. At least half of all
geological deposits have been destroyed again during
slow upheavals. For from the time at which a sea-
bottom formerly lying at a profound depth, with its weil-
preserved enclosures, is again raised within, the reach
of superficial movements, it may be crumbled and cor-
roded, and the fossils contained in it now share the
fate which usually befalls the remains of the denizens of
flat shores, they are triturated by the surf.

To this must be added the important consideration
that the forms by which the transition is effected will
mostly, not as individuals, but as forms, have had a briefer
period of existence than the persistent varieties appear-
ing to us as species, as may be seen, among other in-
stances, in the instructive discoveries at Steinheim. In
this particular, the periods of transition from one geo-
logical plane to the next, resemble the boundary regions
of two geographical districts. The tract of transition
from one to the other is specially suited to give rise to the
transformation of appropriate organisms. But this trans-
formation is accomplished and established first in the new
district. Thus in the geological series, transitional periods
DEFICIENCY OF TRANSITIONAL FORMS. 149

are periods of relative disturbance. During their con-
tinuance the exigency of adaptation and transformation
was at its height, both in the vegetal and animal world;
the conditions of existence at the same time most un-
favourable; the number of individuals in those species
which succeed in effecting their transformation is neces-
sarily reduced, and could increase again only in the sub-
sequent periods of repose. It is therefore not surprising
that the catalogue of intermediate forms is so defective;
and their scarcity is remarked upon only by those who
are determined to feel the want of them. For the estab-
lishment of scientific evidence in favour of the doctrine of
Descent we have them in superabundance.

With the supposed deficiency of transitional forms is
connected another frequent objection, namely, that in re-
peated instances whole groups of kinded species have
suddenly appeared. If intermediate morphological and
anatomical gradations are elsewhere visible, in these
groups, the pterodactyls, birds and others, there is no
coherence and connection with any aboriginal species
previously or contemporaneously existing. This allega-
tion is one of the feeblest and most vapid, if raised after
the attempt has been made to account for the absence
of intermediate forms. It is only a particular case in
the alternative that either all species originated in the
natural manner indicated by the perfectly adequate num-
ber of transitional forms at hand, or all by miracle. In
the cases which are here brought forward as heavy
artillery, the gap to the aboriginal species is certainly
greater than where there is merely a leap from species
tod species or to genus. But the explanation given of
the less striking intervals scarcely needs extension to suf-
150 THE DOCTRINE OF DESCENT.

fice here also. The obscurity overshadowing the extrac-
tion of the birds is just beginning to clear up. Why
should not the origin of pterodactyls become more dis-
tinct in the next few years?

A special difficulty is seemingly prepared for the
theory by the highly integrated organs, particularly by
the apparatus of the senses, with their very complex
mechanism. In truth, taking, for example, the eye of
the Vertebrata, we need not even say of the higher Ver-
tebrata alone; its marvellous structure is well fitted to
excite the liveliest doubts as to descent and selection. As
a matter of fact, indeed, the series of vertebrate animals
does not exhibit the series of lowly beginnings which we
must assume as having once existed. For the eye of the
fish is little inferior in complexity to the optic organ of the
mammal, whilst the lancelet is completely eyeless, and
therefore affords no clue.

In other orders of animals, however, we still see in
the systematic series of the present era every possible
gradation, and thus possess a representation of the man-
ner in which in the paleontological series the perfect or-
gan was gradually evolved from the simplest rudiments.
The lowest crabs present the simplest mechanism im-
aginable, sensitive to light; other crabs of higher devel-
opment possess eyes somewhat more perfect, not only
sensitive to light, but capable of forming images, and
between these eyes and those of the decapodous crab, so
extremely perfect of their kind, a host of optic structures
are represented, which clearly show that these organs are
also subject to the law of slow accumulation and estab-

. lishment of small advantages.
With regard to the auditory and olfactory apparatus,
CONVERGENCE. 151

every manual of comparative anatomy affords testimony
that the series of vertebrate animals now living, present
series of development which negative the sudden and
incomprehensible origination of these organs in an im-
mediate state of completion. How they appeared in yet
lower grades than are exhibited in the true fishes of the
present time we may learn in part from the lancelet, and in
part we may picture to ourselves from the corresponding
sensory apparatus of the lower Mollusca, Articulata, and
Annulosa. With reference to the objections to his doc-
trine arising from the arrangements of the most perfect
organs, Darwin has said that he would abandon his
whole theory if it can be shown that any of these or-
gans could not possibly have been formed {from
lower grades, by improvement slowly acquired. This
demonstration no one has yet undertaken, nor will
it ever be undertaken with success, as every deeper
penetration into the comparative anatomy of the sensory
apparatus affords evidence to the contrary. In order
to understand the presumptively faultless sensory organs
and their derivation from a lower grade, it is of supreme
importance to bear in mind the circumstance first ex-

hibited by Helmholtz in the eye, that besides a num-

ber of perfections, they likewise possess a number of
imperfections, and purposeless or obstructive arrange-
ments.

But we must examine another point, which may
awaken doubts as to the admissibility of the doctrine
of Descent, though, strangely enough, it has as yet been
turned to little account by adversaries, and only inci-
dentally touched upon by Darwin. In the “ Origin of

Species,” he states, that H. C. Watson, we know not
TT
152 THE DOCTRINE OF DESCENT.

where, has opposed to the Divergence of Character, or
the inclination of varieties and species to deviate from
one another,.a Convergence of Character. It is con-
ceivable, he thinks, that species derived from different
genera, might sometimes approach each other so
closely that they would be classed in the same
genus. The author of the theory of Selection has been
content to point out the great improbability of such an
event, which, moreover, in this simplicity would scarcely
impugn the origin and truth of the theory. “If two
species of two allied genera both produced a number of
new and divergent species, I can believe that they might
sometimes approach each other so closely that they would,
for convenience’ sake, be classed in the same new genus,
and thus two genera would converge into one; but from
the strength of the principle of inheritance, and from
the two parent species already differing, and conse-
quently tending to vary in a somewhat different man-
ner, it seems hardly credible that the two new groups
would not at least form different sections in the same
genus.” *

We here see a theoretical objection theoretically re-
futed. But although the probability of a convergence
carried to absolute similarity is extremely slight, and it
receives no support from the palzontological record, its
utter @ priort impossibility must not be rashly asserted;
and in my researches on the Sponges of the Atlantic, I
have pointed out groups of species approximating so
closely as to be scarcely distinguishable. Chalina and
Reniera are two distinct genera, actually belonging to
different families. It is highly probable that the genus
Chalinula, with its extremely variable species, are
CONVERGENCE. 153

branches of the Chalina, not the converse; and the forms
of Reniera likewise merge in species not constant in
any character, and which the most careful observer is
unable to distinguish from the Chalinula. Therefore, if
the convergence or approximation of branches of various
origin cannot be rejected in the abstract, the most pro-
pitious case of coincidence is, nevertheless, limited to the
province of analogous formations, where, under like con-
ditions of adaptation, different families have been driven
to like expedients and differentiations, producing com-
plete similarity. A general survey of the organic world
likewise teaches us, that in the higher regions this over-
lapping of the ends of dissimilar parentage becomes more
and more incredible, and, as is shown by my study on
sponges, they can, in any case, occur only where the
organisms consist of very simple factors, highly variable
in a few directions, and very easily affected by external
conditions.

When we referred above to the possibility of no slight
objection to the doctrine of Descent, we spoke of another
case of convergence. We mean, namely, those similar
final results in divergent series by which, in highly or-
ganized groups of animals, of which the reciprocal con-
nection can be traced only through low aboriginal forms,
certain important organs exhibit the greatest uniformity
of arrangement and integration. It is, as yet, quite un-
decided where and when the true insects separated
themselves from the water-breathing crabs; nay, some
naturalists incline to the opinion that these two classes
are derived from a more remote common ancestor.
Thus much is extremely probable, that the severance
between crabs and insects took place when the develop-
154 THE DOCTRINE OF DESCENT.

ment of their optic apparatus had not attained the degree
of perfection which we now find in the stalk-eyed crabs
and insects. They nevertheless agree not merely in their
coarser conditions, but, as Max Schultze has demon-
strated, even in their minutest microscopic details. If
the idea of design as a principie of explanation is ex-
cluded in this case also, as will be shown below, and as
is self-evident from our standpoint, and if simple heredity
in the two series must be excluded likewise, some other
adequate solution must be sought.

The case of the converging species of sponges may
throw a light, feeble though it be, upon the obscure
processes of the organic laboratory. Let us here again
recall that maxim of Goethe, which we have already cited:
“The animal is formed by circumstances for circum-
stances.” Perhaps this maxim may in future be brought
into play, for it is actually a question of investigating
how surrounding conditions, the agencies acting on the
sensory apparatus, can exercise on simple matter such
an influence, that the otherwise widely differing descend-
ants of the various possessors of this simple material or
incomplete organs, have acquired a more complete organ,
not only working in a similar manner, but of similar con-
struction. Darwinism has never yet pretended to have
explained everything; neither will it be wrecked on this
point, but, on the contrary, will only have supplied fresh
incitements to more profound researches, crowned by
beautiful results.

Another example of approximation in divergent series
is afforded by the eyes of the highest molluscs, the
Cephalopods, as compared with those of the Vertebrata;
in this instance, however, it does not go beyond an anal-
SYSTEMATIC SCHOOL. 155

ogy, though a striking one. It is only the microscopic
structure of the nerve membrane, which is extremely
similar in both divisions, with the exception of the re-
versed sequence of the layers from inwards, outwards.
The case, considered in the abstract, appears highly com-
plicated, and without a prospect of solution; but it be-
comes marvellously simplified, as we have already hinted,
if the question is thus generalized: In what manner are
the still undifferentiated terminations of the nerves af-
fected by the specific operation of the waves of light
and sound, &c., so as to assume the form and construc-
tion of specific peripheral organs? It may be long be-
fore these relations are fathomed; our only concern is
to defend the theory from the reproach of inadequacy,
by showing the scope for investigation according to our
point of view.

When Darwin had brought to light the effects of
natural selection in reproduction and derivation, and ap-
plied this principle to all the phenomena of the organic
world, the Doctrine of Descent, thus fortified and estab-
lished, practically subdued the systematic school which
Lamarck had vainly resisted, to the theory of transmu-
tation. The systematic school classified organisms ac-
cording to external and internal resemblances. Whence
this greater or smaller accordance, whence the grada-
tion and the heterogeneity, it knew not how to tell. It
was thought that much was gained when the fundamental
forms of types were spoken of, even though no account
was given of the intrinsic nature of these types, floating
like ideas above the phenomena. Now the type has be-
come the family, and the systematizers have the plain
task of restoring and combining the pedigrees of the
136 THE DOCTRINE OF DESCENT.

various groups of living beings. The knowledge of
these pedigrees has now for the first time a truly sci-
entific purport, as compared with the old system of
types; for the genealogical trees cannot be constructed
without a knowledge of their growth, and of the causes
which produced their branches, twigs, and shoots. ;
Each family thus includes all the forms derived from
one simple original form. The old systematic school
was obliged to content itself with working out the classi-
fication of the individual types, and defining their
limits, and then balancing the types against each other
on general morphological and physiological principles,
in order to estimate their relative value, all without any
consciousness of the natural causes of these actual
relations. The doctrine of Descent connects the
original forms of the types afresh from the point of
view of consanguinity, and descends deeper and deeper,
down to the simplest organisms, and the beginning of
life.

But before we attempt to come to an understanding
as to the origin of life, one of the pillars of the doctrine
of Descent, it seems appropriate to allude to the question
whether natural selection, of which the means and effects
will be more minutely elucidated in the following chap-
ters, is capable of explaining all the modifications of or-
ganic beings, and whether selection must always be sum-
moned to aid in the explanation of these transformations?
In other words, whether the theory of selection answers
all the requirements of the doctrine of Descent, or
whether it is capable and in need of amendment? We
may do this with the more impartiality, as the acute
author of the book entitled “ The Unconscious from the
IS THE THEORY OF SELECTION SUFFICIENT? 157

Standpoint of Physiology and the Theory of Descent.”
(Das Unbewusste vom Standpunkt der Physiologie and
Descendenztheorie),** has again recently observed that
the truth of the doctrine of Descent is independent of the
bearings and adequacy of the Darwinian theory.

“This circumstance,” he says, “is misunderstood by
the majority of Darwin’s opponents; when they adduce
arguments for the inadequacy of natural selection in the
struggle for life, they usually fancy they have adduced
just as many arguments against the reliability of the
theory of Descent. But the two have no direct connec-
tion with one another; for it might be possible that Dar-
win’s theory of natural, selection was absolutely false and
unserviceable, and the doctrine of derivation true not-
withstanding; that only the causal medium of the der-
ivation of one species from another was different from
that stated by Darwin. Similarly, it might be possible
that, although the immediate causes of transition discov-
ered by Darwin were partially effective——on the other
hand, transitional phenomena existed which could not as
yet be explained by this hypothesis; that this therefore
required either an auxiliary hypothesis supplementing
that of Darwin, or even a co-ordinating principle of ex-
planation, as little discovered naw as was the Darwinian
theory twenty years ago. Such imperfect knowledge of
the causes operating in the transition of one form into
the other, can prejudice the general truth of the doctrine
of Descent as little as the absence of intermediate forms,
or the uncertainty, still existing in many cases, of the
derivation of any given form. If even ! former times,
when all knowledge of the causes by which transition
is effected was still wanting, the doctrine of Derivation
158 THE DOCTRINE OF DESCENT.

seemed certain to the greatest minds, on philosophical
and @ priori grounds, there can be still less doubt as
to the theory of Descent, now that Darwin and
Wallace have plainly shown that indubitably the
most important, if not the all-sufficing cause of
transition is everywhere effective, and in many cases
sufficient.”

We wished to set forth these words of a talented
philosopher for the benefit of those who are so unreason-
ing as to pour away the child with the bath-water, and
fancy that they have slain the doctrine of Descent when
they have been lucky enough to raise a few cavils against
Darwin’s theory of selection. Does the theory of selec-
tion fulfil every requirement? It accomplishes many
and great things, but in some cases it seems to be. in-
adequate, and in other cases it is not requisite, as the
solution of the formation of species is found in other
natural conditions.

Moritz Wagner, a decided adherent of Metamorphosis
and an enthusiastic admirer of Darwin, endeavoured to
establish a “ law of migration,” namely, that “ the migra-
tion of organisms and the formation of colonies by them
is the necessary condition of natural selection.” ** In
his opinion, new species arise only when smaller com-
munities of individuals, in process of forming varieties,
are geographically isolated, as in this manner only is
intercrossing precluded with their stationary congeners,
who do not participate in the transformation; and rever-
sion and disappearance of characters as yet not fixed
is thus avoided.” That isolation often acts very favour-
ably on the formation of species is a fact almost univer-
sally acknowledged and easily verified by insular fauna,
LAW OF MIGRATION. 159

but that the formation of species can take place only
with the assistance of isolation has been effectively
refuted by Weismann.*® He has shown that an “ inter-
crossing of the incipient variety with the aboriginal form
is not avoided by isolation;” through the instance de-
rived from the Steinheim lake, of the formation of a
new species amid the older formations. On Haeckel’s
remark that in the asexual propagation of the lower
beings, the influence of intercrossing was not to be
feared, Wagner had already restricted the necessity of
isolation to the higher organisms with separate sexes.
But Weismann most justly insists that Wagner’s “ law
of migration” is deprived of all foundation by one of
the most remarkable examples of the formation of
varieties on the same territory, namely, the fact of the
separation of the sexes, as to the derivation of which
from. species once hermaphrodite, all (the believers
in Creation naturally excepted) are assuredly of one ac-
cord.

As we have already mentioned, it seems as if the
impulse to form varieties once exists, the tendency
spreads rapidly. Proof of such periods of variation is
to be found in the Paleontological investigations on
page 96. If isolation coincides with such a period, it
effects the establishment of new varieties into species
without the aid of natural selection. As Darwin ad-
mits in his work on the origin of Man, he formerly be-
stowed too little attention on the formation of so-
called morphological species. By this we mean, species
not distinguished from their aboriginal stocks by any
physiological advantages, and hence not superior to them,
in which therefore the principle of selection in the strict
160 THE DOCTRINE OF DESCENT.

Darwinian sense is inapplicable. Two species of but-
terflies, differing only in a few specks or pencilings, or
the notches on the wings, are in our estimation of per-
fectly equal physiological value; they are morphological
species. Weismann sets up the proposition that “the
colouring and penciling of the upper surface of the
wing in butterflies are to be regarded as purely morpho-
logical characters, excepting in cases of mimicry and
protective uniform colouring.” He shows also by other
examples that, “ under certain circumstances and within
a comparatively small range, new as well as morpho-
logical characters may be established by the effects of
isolation only.” The inapplicability of natural selection
to the evolution of purely morphological variations was
first pointed out by Nageli.*® With reference to this sub-
ject, Darwin with magnanimous modesty observes: “ I
now admit, after reading the essay by Nageli on plants,
and the remarks by various authors with respect to ani-
mals, more especially those recently made by Professor
Broca,®° that, in the earlier editions of my ‘ Origin of
Species,’ I probably attributed too much to the action
of natural selection or the survival of the fittest. I have
altered the fifth edition of the ‘ Origin’ so as to con-
fine my remarks to adaptive changes of structure. I
had not formerly sufficiently considered the existence of
many structures, which appear to be, as far as we can
judge, neither beneficial nor injurious, and this I believe
to be one of the greatest oversights as yet detected in my
work,” :

We are disposed to think that the oversight with
which Darwin charges himself is not so great, as it is
here a question of the more indifferent species, not affect-
ORIGIN OF LIFE. 161

ing the great phenomena of progressive development,
and of which the origin is perfectly comprehensible by
variability alone, or in any case, as we have seen, by
variability with the co-operation of isolation. The value
of natural selection is in no way deteriorated by the
possibility of explaining the purely morphological
species without its aid. In certain cases of mimicry,
or the formation of natural protective masks and imi-
tations, and for the explanation of organic beauty,
natural selection seems inadequate. But what does this
prove, but that, as all know, future generations must
needs carry on the edifice? The additions contributed by
the Present to the theory of selection are scarcely worthy
of mention.

As the type has become the family, and the system,
as the shortest expression of the kindred relations of
organisms, requires at the root of the genealogical tree
a number of the lowest and simplest organisms, or per-
haps one single primordial form, we must come to an
understanding as to the problem of the beginning of life.
Even quite recently, in March 1873, Max Miller, in
accordance with an opinion shared by many, has again
proclaimed “ the Darwinian theory vulnerable at the be-
ginning and at the end.”*? Whether any considerable
points of attack are offered by the final proposition of
Darwinism, namely, the application of natural selection
to man, and his sole characteristic peculiarity, language,
we shall have another opportunity of inquiring. But
what the renowned linguist terms the vulnerable begin-
ning of Darwinism, the origin of life, has in fact nothing
to do with actual Darwinism, or natural selection, unless
the principle of selection be extended to the inorganic
162 THE DOCTRINE OF DESCENT.

world of matter. But the objection which endeavours
to cut away the ground from under the doctrine of
Descent, not the theory of selection, and represents the
origin of life as incomprehensible and supernatural, we
naturally regard as an attempt to gain a precedent for
the supernatural creation of language. Between begin-
ning and end, we naturalists may do as we please.

But it is strange that the very side which is so ready
to reproach us with a want of philosophic method and
induction, should here, where the material substratum
is deficient, dispute the claims of the investigation of
nature to its logical inferences. In the last page of
the “Origin of Species,” Darwin says: “There is
grandeur in this view of life, with its several powers,
having been originally breathed by the Creator into a
few forms or into one; and that, whilst this planet has
gone cycling on according to the fixed law of gravity,
trom so simple a beginning endless forms most beautiful
and most wonderful have been and are being
evolved.” In this concession, Darwin has certainly been
untrue to himself; and it satisfies neither those who be-
lieve in the continuous work of creation by a personal
God, nor the partizans of natural evolution. It is directly
incompatible with the doctrine of Descent, or, as Zollner *°
says: “ The hypothesis of an act of creatiom (for the be-
ginning of life) would not be a logical but a merely
arbitrary limitation of the causal series, against which
our intellect rebels by reason of its inherent craving for
causality.” Whoever does not share this craving is be-
yond help, and he cannot be convinced. To hold the
beginning of life as an arbitrary act of creation, is to
break with the whole theory of cognition.
BEGINNING OF LIFE. 163

The verdict, as to the beginning of life, is commonly
dependent on the standpoint adopted with respect to
the possibility of primordial or spontaneous generation
(generatio equivoca). This course is, in our opinion,
only half correct. The subtlest experiments on spon-
taneous generation, whether from organic matter or from
constituents not yet combined into molecules of organic
matter, have proved indecisive on both sides. Neither
the impossibility nor the possibility can be experi-
mentally demonstrated; it always remains open to the
sceptic to say, if nothing appears, that the failure of
spontaneous generation is due to the conditions of the
experiment; or if anything does make its appearance,
that, notwithstanding every precaution, germs made their
way into the infusion. Opinion as to continued
primordial genesis still taking place, is thus a mere
emanation of the general theory of nature held by each
individual. To any one who holds open the possibility
that, even now, animate may be evolved from inanimate
existence, without the mediation of progenitors, the frst
origin of life in this natural method is at once self-evident.
But even if the proof were given, which never can be
given, that in the present world spontaneous generation
does not occur, the inference would be false that it never
did occur. When our planet had reached the phase of
development in which the temperature of the surface ad-
‘mitted of the formation of water and the existence of
albuminous substances, the quantitative and qualita-
tive conditions of the atmosphere were different from
what they now are. A thousand circumstances now
beyond our control, and as to the possible nature of
which it is needless to speculate, might lead to the pro-
164 THE DOCTRINE OF DESCENT.

duction of protoplasm, that primordial organism, from
the atoms of its constituents.

Hence the beginning of life at some bygone period is
likewise not susceptible of demonstration; but the com-
mencement of animate being at some definite era of de-
velopment is a logical necessity, and by no means a vul-
nerable point in the doctrine of Descent.*+

We have already incidentally mentioned a man who,
although not so eminent as Darwin, has the glory of
having independently discovered the law of natural se-
lection, and of having, after Darwin had come forward
with his fundamental work, supported the theory of se-
lection by a profusion of original observations. This is
Alfred Russell Wallace.®> Ina paper, published in 1855,
he demonstrated the dependence of the flora and fauna
on the geographical position and geological nature of
the district of propagation, and the close connection of
the species, according to time and habitat, with kindred
species previously existing; and in a second work, in
the year 1858, on the inclination of varieties to deviate
without limit from the original type, we find a disquisi-
tion on the importance of the struggle for existence, the
consequences of adaptation, the selection of the most
useful, and the replacement of the earlier species by the
establishment of the more valuable varieties. We shall
repeatedly have occasion to draw upon the rich sup-
plies of his researches.
VII.

Heredity—Reversion—Variability—Adaptation—Results of Use and
Disuse of Organs—Differentiation leading to Perfection.

THE two properties of organic being which determine
and regulate the relation of the offspring to the pro-
genitors, and which not only assign to individuals their
position in the surrounding world, but also help them
to attain it, are transmission or heredity, and adaptation.

Heredity is the conservative, adaptation, the pro-
gressive principle. Yet all heredity is not directed to
immutability, and many cases of adaptation involve
morphological and physiological retrogression. For the
elucidation of the inherited peculiarities of organisms, we
reconstruct their pedigree; by the characters acquired
by adaptation, we test the pliability of organisms in the
lapse of time, and trace the ramifications of the pedigree.
Groups of organisms, in which the conservative principle
predominates, certainly evince their powers of endurance
in the struggle for existence, but they make no advance
in physiological value, and are outstripped by the more
progressive groups which yield to obstacles and profit by
them, a course of which human life also affords so many
examples.

As the phenomena of heredity are usually more obvi-

ous than the results of adaptation, the latter was almost
165
166 THE DOCTRINE OF DESCENT.

entirely neglected by naturalists in former days. And
indeed what comparison in organic nature can be made
so frequently and universally as the resemblance of the
offspring to the parent? An anatomist, it is true, quaintly
attempted to work out the proposition that the resem-
blance in the children is not dependent on heredity, but
is the result of identical and similar influences, customs,
and habits, prevalent in families. But this paradoxical
theory requires no special refutation. It is quite true
that similar habits and similar external impulses elicit a
certain similarity of demeanour and appearance; but if
the little son of the pompous millionaire apes his father,
it cannot be said that he has likewise mimicked his large
or small nose, &c., or has acquired it by a similar call
for adaptation. We have only cursorily alluded to this
quibble, in flagrant contradiction as it is with every ex-
perience; and, in conformity with general opinion, we
corroborate the transmission of the parental characteris-
tics to the offspring. The breeders of animals in particu-
lar has occasion to observe these transmissions spe-
cially, and to evolve their astounding progress from the
combination and reciprocal influence of the various forms
and degrees of heredity.

It is well known that not only are normal conditions
transmitted, but monstrosities are also reproduced
through several generations, and, as we have seen in the
instance of the crooked-legged sheep of Massachusetts,
may even be established as the characters of a race. A
mere reference to the inheritability of morbid tendencies,
bodily and mental, will enable us to realize this intrinsic
connection of the offspring to the ancestors. Only since
the theory of selection has rendered the modalities of the
HEREDITY. 167

transmission of bodily characters a subject of more pro-
found study, have general and national psychology been
impelled to estimate the influence of heredity in the
province of the mind, and demonstrate how, in the vari-
ous races and families of nations, the molecular peculiari-
ties of the brain, the tendency of character and intelligence
of the individuals, and whole series of ideas, conform both
in vigour and purport to the laws of heredity.

It is manifest that the key to the phenomena of hered-
ity must be looked for in the. process of reproduction.
The molecular motions and disturbances, the inconceiv-
ably minute mechanical transfers which take place, do
not, indeed, admit of observation. They are, however,
no more “obscure” and “ enigmatical,” as they are so
readily termed, than the invisible, but not supernatural
motions, on the control and calculation of which the
stately edifice of theoretic Chemistry and Physics se-
curely rests. With the advance from asexual to sexual
reproduction, and from the simple to the more perfect
organisms, the difficulty of representation increases, but
not that of abstract comprehension. If a low organism,
a monad, divides itself, the divided individuals differ from
the parent individual only in their inferior bulk, and the
difference of their functions is, as to quality, nil.

So, too, where gemmules and germs separate from a
parent organism, the dower of the offspring is so large
that identity in form and function of progenitor and
progeny appears self-evident and natural. But the sexual
reproduction of composite organisms is, as we have
known since the old doctrine of the aura seminalis was
refuted, also a separation of material portions of the pa-

rental organisms. It is still a mechanical process which
I2
168 THE DOCTRINE OF DESCENT.

is not incomprehensible, and seems inexplicable only if
we make the naturally futile attempt to bring sensibly
before us the infinitely minute agencies which operate
both mechanically and chemically. In the ‘‘ Variation of
Plants and Animals,” Darwin has set up a provisional
hypothesis of Pangenesis. He says that all phenomena
of heredity and reversion would thereby be rendered pos-
sible, that in every elementary or cellular portion of the
‘ organism innumerable gemmules are produced, which
are hoarded up in the reproductive elements, in every
ovum, in every sperm corpuscule, and might remain
latent during hundreds of generations, and only then
exhibit their powers in reversion.*® This hypothesis, it
appears, has met with no ready approbation, probably,
as it seems to us, because, in the attempt to meditate
upon it, the sensible representation forces itself forward
only to prove inadequate. But if it be steadfastly borne
in mind that in Protoplasm, as Rollet *7 appropriately
terms it, the most complex phenomenal forms of life pos-
sess a most persistent witness of their connection with
the simplest, it follows that the general laws shown to
be true or probable with reference to the simplest or-
ganisms, must be applicable to the most perfect also.
This holds good also in reproduction, which, in its funda-
mental phenomena, offers nothing that cannot be based
upon molecular physics applied to colloidal living sub-
stance capable of imbibition, and thus divested of vitalistic
dualism.

The more highly complex is an organism, that is, the
greater the differentiation in the development from the
protoplasm of the germ-cell to maturity, the more
heterogeneously does heredity display itself. These
REVERSION. 169

modes of heredity have been defined by Darwin, and
yet more systematically by Haeckel, as “laws of in-
heritance,” and corroborated by them by a profusion
of examples. If heredity may be termed the conserva-
tive element in the life of species, we may also speak
in particular of a conservative heredity, by which the
old, long-established characteristics and peculiarities are
transferred. The more stubbornly a character is trans-
mitted, or, what amounts to the same, the greater the
number of families, gcnera, and species, over which a
character is extended, the more ancient must it be con-
sidered, the earlier did it appear in the ancestral stock.
In most cases, this conservative heredity occurs in an
unbroken succession of generations, an observation on
which it is needless to enlarge, as it may be daily made by
every one. But conservative heredity may likewise dis-
play itself intermittently, either when merely individual
characters of the ancestors reappear after lying dormant
for one, several, or many generations,—a phenomenon
designated as Atavism, or reversion,—or when the species
is composed of a regular alternation of variously con-
stituted generations and individuals. ‘This particular
sort of reversion is termed Alternate Generation, or
Heterogenesis.

No one is surprised if children exhibit the bodily or
mental features of their grand-parents which were sus-
pended in the parents. But most frequent and striking
is the atavism of domestic animals and cultivated plants,
a stubborn antagonist to breeders. Of no domestic ani-
mal is the aboriginal stock known with such approximate
certainty as that of the pigeon. Now there are races
of pigeons purely bred for several centuries, and in
170 THE DOCTRINE OF DESCENT.

colour and shape transformed into new creatures,
which yet from time to time spontaneously, or by
crossing with other conspicuous races, produce birds
which, in colouring and characteristic pencilings of
black bars on wings and tail, resemble the wild rock-
pigeon.

“T paired,” says Darwin,®* “a mongrel female barb-
fantail with a mongrel male barb-spot, neither of which
mongrels had the least blue about them. Let it
be remembered that blue barbs are excessively rare; that
spots, as has been already stated, were perfectly char-
acterized in the year 1676, and breed perfectly true; this
likewise is the case with white fantails, so much so that
I have never heard of white fantails showing any other
colour. Nevertheless, the offspring from the above two
mongrels was of exactly the same blue tint over the
whole back and wings as that of the wild rock-
pigeon of the Shetland Islands; the double black
wing-bars were equally. conspicuous; the tail was exactly
alike in all its characters, and the croup was pure white.”

Another reversion frequently to be observed is the
striping of the feral domestic cat of Europe, in which
it resembles the wild-cat so closely as to be scarcely
distingdishable. Darwin has collected evidence from
which we may infer that the wild ancestral stock of
the horse was striped, and this evidence includes the
appearance of striped individuals. But yet another
strange phenomenon in horses may be interpreted by
atavism. Foals are occasionally born with supernumerary
toes. This “monstrosity” can be explained only by
reversion to the three-toed historical ancestors of the
present genus. These vouchers are sufficient.
PROGRESSIVE HEREDITY. 171

All the phenomena of artificial breeding, as well as
natural selection, serve to show that not only the char-
acters descended from past ages, but also those subse-
quently and most recently acquired, may be transmitted
to posterity. This is progressive heredity. Without it,
improvement and progress would be impossible; and its
own possibility is the direct result of the nature of re-
production. The newer a useful modification, the less
has it hitherto been able to place itself in correlation
with the entire organism, the less is the reproductive sys-
tem as yet affected by it; the more uncertain and fluc-
tuating, therefore, is the transfer by propagation; breed-
ing, or natural selection, is requisite to convert the po-
tentiality of progress into a fact, and gradually to enrol
this fact among the conservative inheritances.

Progressive heredity is naturally more complex where
the sexes are separate, where sexual selection asserts
its rights, and the advantages of one sex are fostered
by the taste of the other, and are then either trans-
ferred exclusively to the sex benefited by its secondary
characters, or turned to the profit of the whole species.
As a rule, the males are endowed with these advantages,
and have transmitted them incompletely to the females.
We will explain ourselves by a single example. In the
order of insects termed Orthoptera (or straight-winged),
the males, by rubbing their wing-covers together, or by
stroking them with the lower portion of their hind legs,
are able to make a music attractive to the females.
Von Graber, a distinguished modern entomologist, has
shown °° that the teeth of the stridulating instruments of
these animals are merely modified hairs; that their con-
struction may be explained by their use; and that in all
172 THE DOCTRINE OF DESCENT.

probability they have been perfected by sexual selec-
tion, the best and loudest musicians being the most
favoured wooers. With one single exception, the fe-
males of the Orthoptera are dumb, but many possess
traces of the stridulating apparatus peculiar to the males.
Contrary to the older opinion, that it was merely a case
of transmission emanating from the males, Graber has
made it ‘‘ more than probable that the resonant nervures
of the females—of the stridulating Ephippigera vitium—
have been gradually developed independently of the
males, but in the same manner.” In other cases, on the
contrary, the feebly developed nervures of the females,
unfit to produce audible stridulations, seem to be an in-
heritance from the males.

Heredity at corresponding periods of life is a well-
known phenomenon. The tendency to disease is trans-
mitted from the father or the mother to the child to
break out at the age at which they suffered. Generation
after generation, the milk teeth make room for the per-
manent teeth at a corresponding time. ‘But all special
cases are mere results of the general law of develop-
ment, by which in the individual characters appear in
the sequence in which they were historically acquired
and became susceptible of transmission. Heredity, at a
definite age after the period at which we consider actual
development to be complete, is after all only a continu-
ation of the embryonic development, beginning with
fission, germ and ovum, of which the ninth chapter will
teach us the signification. In this development of the
individual, or ontogenesis, as will be shown below in
more detail, processes are frequently abridged or totallv
omitted which once, while they were being acquired and
MUTABILITY. i 173

after they had been established, occupied a longer period,
but in the course of selection either became of less im-
portance to the individual, or preserved a physiological
value only as phases of transition.

The second great class of characters, namely, those
which have been newly acquired and depend on adapta-
tion, pre-suppose the mutability of the organism. This
is a fundamental phenomenon of organic bodies. It is
inherent in the minutest morphological constituents, in
protoplasm, and in cells, and in the morphological ele-
ments evolved from them, the pervading and determining
individual life of which results in the collective life of the
creature. The organic morphological element is in a state
of saturation; it is continually imbibing and emitting,
and its stability is therefore constantly dependent on the
supply of material for its functions. For nutrition, which
generally and wholly determines the external appearance
and the nature of the individual, is accomplished by the
innumerable cells and their derivatives. Every fluctua-
tion of supply to any part of the organism, nay, to a
single point of the surface of a microscopic atom, must
involve a modification of textural parts, or in the struc-
ture of integrated textural groups or organs.

Mutability is thus a character resulting from the in-
trinsic nature of organism, and dependent on external
conditions, which determine quantity and form, as well
as the development and transformation of the ele-
mentary constituents, or their abortion and _ retro-
gression. These effects may be exhibited in a polype-
stem, which as a whole represents the individual, in its
single polypes, the cells and morphological elements.
The single individuals are alike in their constitution, but
174 THE DOCTRINE OF DESCENT.

are usually very different in size and development, even
in those species in which the differentiation unquestion-
ably produced by selection has not led to polymorphism
‘or separation into personal groups performing different
functions. The weal or the woe of our polypes is greatly.
dependent on the position which they occupy upon the
stem; the supply of nutriment primarily furnished to
the single individuals is unequally and variably appor-
tioned according to currents and tides. Hence on each
polype-stem there are regions where the single polypes
are especially thriving, others where they are just able
to maintain themselves, others where they cannot keep
their balance. But as the polype-stem is traversed by
a canal system conveying the nutritive fluid and con-
necting the several cells, the superfluity of the well-
situated cells goes to the benefit of those for whom a
worse lot was prepared by their accidental position, and
conversely. These relations, which, complex as they
seem, are very simple for our comparison, determine the
form and appearance of the polype-stem. Among a
hundred thousand stems, no two will be found absolutely
alike.

To return to the mutability of organisms, even if
two individuals of the same species are bred under the
most similar conditions imaginable, it has never been
possible to pronounce them absolutely alike. That mu-
tability is slighter in lower than in higher organisms,
is a prejudice frequently repeated and fortified by the
old dogma of species. The doctrine of descent and se-
lection would fare ill if the case were so. But as the
shepherd unerringly knows the physiognomy of his
sheep where an excursionist from the town sees only
ADAPTATION. 175

a general sheep’s face, so to an attentive naturalist, in
most of the lower organisms, the specific type re-
solves itself into as many varieties as individuals, irre-
spectively of the cases in which no specific type can be
established.

As modification under given conditions, adaptation is
thus as little an unknown quantity as heredity, but is
merely a function of the mechanical character of muta-
bility, or, in the widest sense of the word, of nutrition.
Adaptation takes place when the organism or its parts
are pliable and plastic to external influences, when they
conquer and make use of them. Climate, light, humid-
ity, nutriment, are hindrances or advantages that directly
or indirectly affect the organism, and are all actively
concerned in it. Surrounded by organisms, we see them
without exception adapting themselves to circumstances;
and if our only object is to be convinced of the formative
influence of the mode of life, this is most readily done
in the case of domestic animals. In his studies on the
pig, H. von Nathusius, perhaps the most scientific, of the
celebrated breeders, shows how in the simplest cases,
where the looseness of cultivated soil has facilitated the
labour of grubbing, the skull of the domestic pig is ar-
rested, by the softer structure of the cranium, at the im-
mature form of the wild boar, and how those extreme
shapes of the head in cultivated breeds, characterized by
the bending and shortening of the face, and the impossi-
bility of closing the jaw in front, are entirely the result
of their altered mode of life. It is known that men,
animals, and plants, removed far from their previous
abode to a new and strange environment, after a longer
or shorter effort of the organism to domesticate itself,
176 THE DOCTRINE OF DESCENT. ‘

either die out, or else accommodate themselves to the
new conditions and become acclimatized. Every accli-
matization is therefore an adaptation, accompanied by
modifications more or less perceptible. Thus, in conse-
quence of the varied conditions of life, there is a wide
divergence among races of men who, by their kindred
language, are of the same origin, not to mention those
whose relations linguistic inquiry has not yet decided.
How different is the idiosyncrasy of the Englishman
from that of the Hindoo! Physically and psychically,
they represent two remarkable sub-races of which the pe-
culiarities must be ascribed to adaptation,—in the latter,
to a climate which requires a vegetable diet, and, eliciting
neither bodily nor mental energy, favours a dreamy
sensuality; in the former, to a country which is in every
particular the opposite of the Indian original home.
Similarly, the annual alternation in the vital phenomena
of so many organisms, designated as hybernating ani-
mals, is a case of adaptation. It is changed the moment
the organism is exposed to another climate, or rather
acclimatization is essentially the accommodation of the
hybernating animals to the new climate.

In all these examples we have the results of direct
adaptation, in which the power of resistance in the in-
dividual comes into play, as does cumulative adaptation
in artificial, and the survival of the fittest in natural,
selection. In all cases of adaptation, one or several or-
gans are primarily concerned, either actively or passively;
and only in consequence of the resulting modifications
are the other organs drawn into sympathy. This may
be termed correlative adaptation. It might be supposed
that the most perspicuous examples would be afforded
CORRELATIVE ADAPTATION. 177

by parasitic animals, in which, with the alteration of the
aliment and of the alimentary apparatus, especially of
the manducatory portions, is usually combined a trans-
formation and retrogression, often extending to the total
extinction of the locomotive organs, and of the entire
segmentation of the body. But, although the limits are
difficult to define, the cause of these associated modifi-
cations in the locomotive and alimentary apparatus con-
sists less in their reciprocal sympathetic influence than in
their simultaneous disuse.

It is, however, by correlative adaptation that, for in-
stance, in the short-beaked races of pigeons, the middle
toe and astragalus are shortened, and that in the long-
beaked races these organs have shared in the elongation.
In the case, however, in which short beaks are combined
with short feet, a certain share in the shortening of the
feet is also owing to disuse; while where the pigeon-
fancier took pleasure in the elongation of the beak by
cumulative selection, the correlative elongation of the
foot took place in spite of disuse. The most important
group of correlative modifications or adaptations, always
using this word in its widest acceptation, relates to the
sphere of the sexes. Direct attacks on the generative
organs manifest their effects on all the rest of the or-
ganism, as is best shown in animals of both sexes cas-
trated for the market or for labour.

We have already seen that the degree of perfection
attained in the orders of the Articulata, Annulosa,
Vertebrata, and partially in the Radiata also, depends
on the integration of the originally similar parts lying
behind or by the side of one another; hence on the di-
vision of labour. This Haeckel has designated divergent
178 THE DOCTRINE OF DESCENT.

adaptation. It gives rise to the remarkable poly-
morphism, which appears especially in the marvellous
forms of the Hydra tuba; and, higher up, in the
organization of the communities of the Termites and
the Bee, &c.

So far as modification coincides with adaptation, the
direct adaptations hitherto discussed may be contrasted
with a series of indirect adaptations. Among these may
be comprised a series of phenomena of which the causes
do not fall within the life of the individual, but are to
be sought in influences by which the parents were af-
fected. It is obvious that we here come into contact with
the province of heredity, which is well known to breeders.
Thus H. v. Nathusius, in his studies on the formation
of the pig’s skull,*t says:—‘‘ From the facts here col-
lected, it is plain that the transmission, the transfer of
the form of head from the parents to the offspring, does
not unconditionally ensue. If the form of skull, which
we will briefly term the cultivated form, be the product
of nutrition and mode of life, hence of external influ-
ence,—if it can be differently formed in the same indi-
vidual, and is therefore not constant,—in that case the
heredity of this form cannot be spoken of without quali-
fication. The form itself will not be transmitted to the
offspring, but only the tendency to the form. This may
be inferred from the circumstance that from generation
to generation, and to a certain degree, the form increases
in peculiarity. If we rear a common with a thorough-
bred pig, and if we allow exactly the same influences
of nutriment and keeping to operate upon both, and in
equal measure, we shall not obtain the same form of
head. The development of the form of head must there-
MIMICRY. 179

fore be aided by a pre-existing tendency, and we must
hence regard it as hereditary.”

Haeckel likewise propounds a law of individual
adaptation, which expresses the fact that, notwithstand-
ing the closest kinship, individuals diverge in many ways.
The cause of this difference, chiefly conspicuous in the
individuals of the same litter or brood, is, so far as it
is not due to adaptation, inherent in the germs, and is
transferred to them by fluctuations and differentiations
in the conditions of nutrition in the parents, mostly be-.
yond our ken. Other phenomena of indirect adapta-
tion are exhibited in the occurrence of malformations,
of which the causes must be looked for only in dis-
turbances of nutrition in the parental organisms by
which the progenitors themselves were not percepti-
bly affected. Here also belong the cases, in which
influences which have affected one sex only are mani-
fested exclusively in posterity in the same sex. As
may be seen, these processes, of which the initia-
tion is entirely withdrawn from observation, are
closely connected with the most obscure province of
heredity.

An extremely interesting and important form of
adaptation is the so-called mimicry, or protection by
means of colouring and form. The first discoveries
on this subject were made by Bates, the well-known
“Naturalist on the Amazon;” the greater part were
subsequently added by Wallace. In South America,
the family of butterflies named Heliconida is extraor-
dinarily extensive; they are remarkable for their
elongated wings, body, and antenne, and for the beauty
of their colours. It might be imagined they were ex-
180 THE DOCTRINE OF DESCENT.

posed to the persecutions of insectivorous birds and
other animals; but this is not the case, for they have a
disagreeable smell, which, in all likelihood, renders them
obnoxious. Their smell and flavour are thus a protec-
tion, as the birds and lizards who have once seized them
by mistake are certain, ever after, to leave them unmo-
lested. Now, as the insectivora do not test the individual
case, but have adopted a general repugnance to the as-
pect of the Heliconidz, if other butterflies resembled the
-Heliconide without possessing the bad smell, they would
participate in the security to life enjoyed by the Heli-
conide in proportion as they approach their external
appearance. The case has actually occurred, for Bates
discovered a number of species of the otherwise very
different genus, Leptalis, of which each almost undis-
tinguishably resembles one of the Heliconidz both in
colour and form. The Leptalide have also adopted the
flight of the Heliconide, share their habitats, and, al-
though without the offensive smell, fly about with im-
punity. This state of things would be impossible if the
Leptalidze were not considerably in the minority, so as
to be in a measure hidden by the Heliconidz.

Wallace has proved that species protected by mimicry
of other animals are invariably in the minority, and often
very rare in comparison with the species which they imi-
tate. Neither the explanation that like conditions of life
produced like results, nor the hypothesis that, in some
cases at least, the mimicry consists in reversion to a
common original species, is in any way satisfactory.
Many cases can be interpreted only by natural selec-
tion, those, namely, where from the first, before the imi-
tation had begun, such a resemblance already existed
MIMICRY. 181

between the imitating and imitated forms as to render
confusion possible; where, therefore, the resemblance so
conducive to the preservation of those in which it was
the strongest, needed only to be increased by natural
selection. Darwin * is also of opinion “that the process
probably has never commenced with forms widely dis-
similar in colour.”

A peculiar, simpler and long known mimicry, is when
animals have accommodated themselves in colour to
their habitats in such a manner as not to attract the
attention of their enemies, and likewise to deceive their
prey. Who, in the days when he chased butterflies, did
not learn how difficult it is to recognize certain evening
and nocturnal flyers on the bark of trees, as they quietly
sit with their dusky brown or gray-striped or speckled
wings, outspread in a roof-like shape? The tree locusts
and Mantidz can look so deceptively like leaves or
twigs, that it is only by the touch that one can be as-
sured of their real nature. Wallace relates that one of
the Phasmide (Ceroxylus laceratus), which he obtained
at Borneo, was so covered with pale olive-green ex-
crescences, that it looked like a stick covered with moss.
The Dyak who brought him the animal declared that,
although alive, it was really overgrown with moss, and
the naturalist himself was only convinced of the con-
trary by the closest examination.

A remarkable example of advantageous colouring,
within easy reach of many of our readers, is exhibited
in most species of the flat-fish (Pleuronectidz), now so
frequently kept in aquaria. Observe the gray or brown-
ish speckled creatures, as with a few strokes of their
fins they partially cover their upper surface with sand.
182 THE DOCTRINE OF DESCENT.

They need not bury themselves entirely, for it is only
by close examination that their bare skin can be distin-
guished from the sandy bottom, and under this partly
artificial, partly natural veil and mask, the animal waits
for its prey.

In many animals provided with protective colouring
the phenomena are more complex, and explanation by
natural selection is far more difficult; for they are able
voluntarily to adapt their colour to circumstances, or else
their colour changes by involuntary reflexes. Verany’s
unsurpassable observations on the Cephalopoda have ac-
quainted us with the range of colours at the disposal of
these Molluscs, and to this may be joined Brehm’s
description of the changes of colour in the chameleon.
On these highly complex cases some light is thrown by
the simpler instances in which the manifestly protective
colouring has become fixed in skin and plumage, and
the concurrence of other circumstances scarcely admits
of any other explanation than selection.

On this point, Wallace’s interesting researches on
bird’s-nests are especially instructive. The great ma-
jority of female birds which sit in open nests possess
brown or gray, in short, unobtrusive plumage. No con-
tradiction will be offered to the statement that any casual
modifications of plumage, which would more readily be-
tray the sitting bird to its enemies, would have no pros-
pect of becoming constant. The converse follows
naturally with regard to colouring which brings the bird
into harmony with its environment; and an important
guarantee of the correctness of this interpretation of facts
is afforded by the other observation, that most female
birds with gaily coloured or speckled plumage sit in cov-
USE AND DISUSE OF ORGANS. 183

ered and concealed nests. It must be added, that the
construction of nests is not determined by the absolute
rules of a blind instinct, but is modified by the experience
of the animals, an experience of which we are indeed
scarcely able to perceive the development, except with the
age of the individual, but which, at least in several cases,
has been proved to be the progress of the species.

Natural selection has an important accessory in the
modifications produced by the use or disuse of organs.
Compulsion to more diligent use, inducements to dis-
use, are involved in the varying conditions of life. In
both cases it is therefore a question of adaptation. Look-
ing at nature, profound modifications are most readily
demonstrated as the consequence of disuse; but artificial
selection gives numerous examples of both sorts, espe-
cially where disproportionate use of certain organs is
combined with simultaneous disuse of others. Such
products of selection with disproportionate use are the
racer and the dray-horse.

The blindness of cave animals admits of no explana-
tion, but that, with the increasing uselessness of the eyes
during accommodation to cave life, the exchange of ma-
terial in the less active organs gradually diminished, and
atrophy was initiated. The accuracy of these theoretical
observations is enforced by the observation that the near-
est kin of many blind cave animals, especially of insects
and spiders, reside in the vicinity of the cave, and that
those cave animals which inhabit passages only partially
obscure, possess less atrophied optic apparatus. A
singular gradation occurs among the burrowing mam-
mals, and Darwin ® cites an example admirably illus-

tating the loss of sight in consequence of the mode of
13,
184 THE DOCTRINE OF DESCENT.

life. “In South America a burrowing rodent, the Tuco-
tuco, or Ctenomys, ‘is even more subterranean in its
habits than the mole; and I was assured by a Spaniard,
who had often caught them, that they were frequently
blind; one which I kept alive was certainly in this con-
dition, the cause, as appeared on dissection, having been
the inflammation of the nictilating membrane. As fre-
quent inflammation of the eyes must be injurious to any
animal, and as eyes are certainly not necessary to ani-
mals having subterranean habits, a reduction in their
size, with the adhesion of the eyelids and growth of fur
over them, might in such case be an advantage; and,
if so, natural selection would constantly aid the effects of
disuse.”

In the classes of flying animals, a large number have
left off flying; and we find their flying apparatus in an
aborted or incomplete condition, which perverse judg-
ment and reasoning alone can regard as a state of pro-
gressive development from yet simpler rudiments. If
throughout the great family of the Coleoptera, genera
and species are to be found with imperfect flying ap-
paratus, consolidated wing covers, &c., if the whole fam-
ily of Staphylinze does not possess the power of flight,
no one dreams of considering them as arrested forms;
but it is conceivable that the mode of life in which they
differ from the other members of their order and class,
gradually superinduced in their flying ancestry the habit
of not flying, and at the same time the atrophy of the
organs of flight. With this was combined, as these
beetles show, no degradation of organization, but, on
the contrary, a higher and extremely advantageous de-
velopment of other organs, the manducatory and loco-
USE AND DISUSE OF ORGANS. 185

motive apparatus. A general reduction of the power
of flight has been shown in the beetle fauna of many
islands. Thus in Madeira, of 550 species, over 200 fly
imperfectly or not at all, and for this there is no ex-
planation but natural selection. Here the less good
and enterprising flyers had the advantage, while the
others were blown into the sea and eliminated. The
non-application of a previously attained special per-
fection is advantageous in the “struggle for exist-
ence.”

In several families of lizards, some genera are ser-
pentine, as they are termed, which, with elongated bodies,
possess either fore-legs only (Chirotes), or merely rudi-
mentary hind-legs (Pseudopus), or no vestiges of legs
(Anguis). They bear the same relation to the great class
of normally four-legged lizards as the non-flying insects
to their own class. They have not been arrested in their
development, nor are they animals in process of evolv-
ing four legs; but, as Fiirbringer has demonstrated from
the history of development and comparative anatomy,
their limbs, and—if these are entirely absent—the remains
of the pectoral and pelvic arches and the sternum bear
indubitable marks of the abortion of a once complete
apparatus. Further comparison shows that this atrophy
reaches its climax in the snakes, but that it is compen-
sated for by the ribs and intercostal muscles having un-
dertaken the work of the limbs. Here, again, disuse and
adaptation coincide as well as differentiation.

In the class of birds is repeated the spectacle we have
just witnessed in beetles and reptiles. In some few
families and smaller groups, individual species are de-
prived of the power of flight, and one whole large sys-
186 THE DOCTRINE OF DESCENT.

tematic group is characterized by the incapacity of fly-
ing. In our opinion, there was a direct connection be-
tween the inducements to disuse and its consequences
in the case of the dodo, which, with its few con-
geners, so promptly fell a sacrifice to its helplessness on
the discovery of the lonely islands which they had prob-
ably inhabited for thousands of years without disturb-
ance. In no other way has the northern penguin (Alca
impennis) at some time obtained the curtailment of its
wings; and the scanty but wide-spread remains of the
order of flightless birds indicate a period at which, in a
more peaceful environment, their far more numerous
-wingless ancestry made less use of their pinions, and
natural selection endowed them with greater strength
and nimbleness of leg. The effects of disuse of the or-
gans of locomotion are likewise directly exhibited by
’ artificial selection. :

Use and disuse, combined with selection, elucidate
the separation of the sexes, and the existence, otherwise
totally incomprehensible, of rudimentary sexual organs.
In the Vertebrata especially, each sex possesses such dis-
tinct traces of the reproductive apparatus characteristic
of the other, that even antiquity assumed hermaphrodit-
ism as a natural primeval condition of mankind. The
technical proofs of the homologies concerning these
partly manifest, partly internal and hidden relations, are
given in the manuals of comparative anatomy. We shall
merely indicate the manner in which the theory of selec-
tion is here borne out. It is self-evident that in her-
maphrodite animals, fluctuations in the sexual sphere
must take place, in which one half or the other will
predominate. Should these fluctuations be sufficiently
PARASITES. 187

strong for natural selection to take possession of them,
the productive power of the less active portion will gradu-
ally decrease, and finally, with the extinction of the
physiological character and the function, nothing will
be transmitted but the morphological remains, as a mock-
ery to the theory of special design or teleology. Here
and there only occurs a reversion more or less striking,
connected, however, almost exclusively with the adjunc-
tive organs, and the secondary sexual characters, by
which we mean, not those acquired by either sex, but
originally common to both. The tenacity with which
these rudiments of sexual organs are inherited is very
remarkable. In the class of mammals actual hermaphro-
ditism is unheard of, although through the whole period
of their development they drag along with them these
residues, borne by their unknown ancestry no one can
say how long.

Unless we suppose that parasitic animals were created
simultaneously with their hosts from the dust of the
earth,—man and his tapeworm, and other disagreeable
guests,—and thus put an end to the discussion, this en-
tire province has to be explained by descent, with the
special co-operation of disuse. The proposition to be
demonstrated in the next chapter, that the evolution-
ary history of the individual represents the history
of the species, will show the influence of the disuse of
particular organs on the configuration of the various
parasites. The parasitic Crustacea are perhaps the most
instructive, as they present the most complete systematic
series, exhibiting the gradual atrophy of the organs which
accompanies the ever-increasing connection of the para-
site with his host. In several orders of intestinal worms,
188 THE DOCTRINE OF DESCENT.

the alimentary canal has become entirely unnecessary;
but they exhibit neither intermediate forms nor phases
of development. It is different, however, with the para-
sitic Crustacean, for here the young, locomotive, and
well-integrated being as its protype in definitive ge-
neric forms permanently locomotive, from which, after
adhesion, it deteriorates into a mere motionless sac. All
these animals, including the intestinal worms, have ac-
quired their position and status (and this is the true
significance of parasitic life) by the apparent degrada-
tion of their organization. They are, almost without
exception, distinguished by their reproductive power;
and on this, owing to the easy supply of nutriment,
without any exertion of the other parts of the or-
ganic system, the whole bodily activity could be concen-
trated.

We have hitherto demonstrated that organisms are
urged to continual differentiation by the unremitting
struggle for existence. For the cultivation of morpho-
logical species, natural selection, moreover, seizes on the
modifications arising from the mere variability of the
organism, and implying no physiological advance. But
sooner or later these are also inevitably drawn into the
vortex of competition. After what has been already
said, this fact is so self-evident as to need no further
proof. Even did we not see the infinite variety of or-
ganisms, a divergence into novelty must needs be in-
ferred on @ priori grounds, from the existence of the
simple and uniform, and the necessity of adaptation to
altered external conditions. But with development in
various directions, under the guidance of natural selec-
tion, progress is necessarily combined. It is one
THEOLOGICAL. INFLUENCES. 189

of the greatest services rendered by the theory of se-
lection, that it has finally broken with the notion of de-
sign, which hitherto invested the organic world with
perfection externally bestowed, and even in the province
of intelligence and morality, where it is said with
Schiller,

So grows the Man as grow his greater aims,*

has secured admittance for the uniform method of natural
science.

It is highly remarkable how the teleological view of
nature could be so long upheld, and is still in part up-
held, by theological influence although in the whole or-
ganic world we behold a merely relative perfection, and
the manifest and multifarious arrangements adverse to
design in every grade of organisms, bear a bad testi-
mony to the external directing Power. The perfection
exhibited by comparative anatomy, and the estimate of
physiological functions is, under all circumstances, the
result of adaptation and selection. In the struggle of
all against all, those individuals win who in any degree
excel their fellows in the division of labour, which, if
the direction of activity be altered, often obliges them
to disuse organs which were once of service, but in the
new conditions are useless, and, it may be generally said,
have become injurious.

Artificial selection—and here we may speak of design
—produces perfection when, by mechanical and physio-
logical labour (the latter especially by means of suit-
able nutriment), it exercises the particular parts which
are to be perfected, and propagates the advantages ob-
tained. What we term natural selection is the epitome

* Es wachst der Mensch mit seinen gréssern Zwecken.
190 THE DOCTRINE OF DESCENT.

of the improvements acquired by specialization in the
process of adaptation. The most faithful image of this
gradually acquired specialization is afforded by the de-
velopment of the individual, where from the undifferen-
tiated, by constantly increasing differentiation, the mature
animal is evolved in the plenitude of its physiological
functions. That in the various animal groups certain
grades of perfection are attained, is an uncontroverted
fact; but every closer investigation shatters the idol of
design. The organism of the bird might induce us to
consider it, in the abstract, as modified for the purpose
of flight. But if design be allowed to watch over the
good flyers, the idea of design must be abandoned with
respect to the non-flyers, and, if some idea is indispensa-
ble, adaptation must have its due. Herewith the whole
theory is broken down, and it will be the same in every
other case.

How organic perfection stands with reference to the
idea of design, has been acutely and clearly expressed by
the author of the “ Unconscious ” (“‘ Das Unbewussten ”).
The theory of descent teaches that there is no inde-
pendence of the conditions co-operating, in an organic
phenomenon; rather that its increasing divergence from
a common neutral point was an effect of the same causes.
The theory of selection makes us acquainted with one
of these causes, and unquestionably the most important
as one, which, by purely mechanical compensative phe-
nomena, produces advantageous results. The theory of
descent merely casts doubts on the teleological principle
by withdrawing the ‘basis for positive proof, but the
doctrine of selection sets it directly aside, so far as it is
able to extend its explanation. For natural selection
‘FITNESS WITHOUT DESIGN. IgI

in the struggle for existence, the extermination of the
less appropriate, and the survival and perpetuation of the
fittest and most appropriate, is a process of mechanical
causality of which the steady conformity to law is no-
where infringed by any teleological controlling meta-
physical principle. This, however, produces a result
essentially corresponding to design; that is to say, it
naturally bestows on organisms the highest capacity for
life under given circumstances. Natural selection solves
the apparently insoluble problem of explaining fitness
as a result, without calling in the aid of design as a
principle.

In each family—for, as we have seen, what zoologists
once designated type, has in the doctrine of Descent
become the family—in each family lies the potentiality
of a certain grade of perfection; and when the main
outline of the family character is established, we see a
development taking place, of which the potentiality is
inherent in the tendency of the character, the realization
and necessity in the external conditions. Hence to us
also, progress is development, but not towards a pre-
destined and pre-established harmony. Karl Ernst v.
Baer,** anxious to rescue design, or at least the “ pur-
pose ”—in short, predestiny, in the evolutionary series of
Nature, says: ‘‘ Every cause engenders a process which
again works on towards another purpose.” But why
purpose? Ought it not rather to be: Every cause en-
genders a process which again works on towards another
process? The further we go back, the deeper and more
general is the grade, and the various ramifications at
their peripheral ends have either halted, or arrived at
very different. grades.
192 THE DOCTRINE OF DESCENT.

An objection frequently made against this result of
the doctrine of Descent is, that if all are pressing for-
ward towards perfection, how is it that, besides the higher,
so many lower members of the family are able to main-
tain themselves, and how can the lower families hold
their own against the higher, in the struggle for exist-
ence? In presence of the irrefutable facts of progress,
it is enough to point out that the lower forms could and
can continue to exist wherever they could find space as
well as the other necessaries of life. While they here
underwent only slight modifications, elsewhere the need-
ful selection led to more profound metamorphoses; and
on a subsequent geographical displacement, the newly
transformed beings, accustomed to other conditions of ex-
istence, were again able to share sea and land with the
stationary species. For as diversity is restored now by
selection, and the demands for nutriment and other neces-
saries are likewise different, a partial remission in the
struggle must take place.

The preservation of a great many inferior organisms
is evidently favoured by the circumstance that just be-
cause they are simpler, their propagation is more easily
effected. Hence although, especially in limited districts,
amid violent competition of superior varieties, countless
species must suffer extirpation, yet the struggle for ex-
istence and.perfection do not exclude the existence of
lower forms. But teleology, as it seems to us, still fails
to explain what has béen explained by the theory of selec-
tion. The retardation of the lower organisms, notwith-
standing the internal pressure and the appointed purpose,
is incomprehensible.

But, it is frequently asked, if you will not hear of
CHANCE. 193

a “principle of perfectibility” inherent in organisms
(Nageli), of the “divine breath as the inward impulse
in the evolutionary history of nature” (Braun), of
“tendency to perfectibility” implanted by the Creator
(R. Owen), even of the “ striving towards the purpose ”
(v. Baer), can chance be supposed to have produced
these marvellous higher organizations? To this it may
be plainly answered, that this chance, to which purblind
humanity allots so great a part wherever the personal
interference of a superior Being or the universal “ crea-
tive and productive principle” is not at hand, has no
existence in nature, and that our conviction of the truth
of the doctrine of derivation is due to its adjustment
of the phenomenal series as causes and effects. Let
us remember, and fancy ourselves in possession of, the
formula of the universe of Laplace, by the aid of which
all future evolutions might be computed in advance.
With our limited powers, it is true, it is retrospectively
alone that certainty can be approached in the calcu-
lation and discrimination of the series. In this we must
obliterate the word chance, for causality, as we under-
‘stand it, makes chance entirely superfluous. Any one
who transports himself to the commencement of an evo-
lution, who, for instance, fancies himself present at
the genesis of the reptiles, may, from his antediluvian
observatory, look upon the development of the reptile
into the bird as a “ chance,” if he does not peradventure
regard it as predestined. To us, who trace the bird
backwards to its origin, it seems the result of mechanical
causes.

Let us now recapitulate what we have gained by
the doctrine of Descent, based on the theory of selec-
194 THE DOCTRINE OF DESCENT.

tion; it is the knowledge of the connection of organisms
as consanguineous beings. The greater the accordance
of internal and external characteristics, the closer is the
kinship. The further we trace the pedigree to its origin,
the fewer become the characters persisting to these
roots, the more do these characters reveal themselves
as acquisitions in the lapse of time. It is by eliminating
these acquisitions and restricting the inherited charac-
ters more and more as we feel our way backward, that
_ we are enabled to reconstruct the pedigrees of the various
groups.®

We do the very thing which in linguistic inquiry is
deemed extremely natural and scientific. The ideas and
words common to the individuals of a linguistic family
are the inheritance from the intellectual and linguistic
property of the original people, from which the pedigree
of the family has ramified. This so-called “ chance”
prevailed in the formation of the derived languages
neither more nor less than in the evolution of organisms
from their original forms.
IX.

The Development of the Individual (Ontogenesis) is a Repetition of the
Historical Development of the Family (Phylogenesis).

ALTHOUGH the paleontological record is full of gaps,
it is nevertheless unmistakable, as even most of the op-
ponents of the doctrine of Descent are ready to admit,
that from the older to the more recent period, a progress
takes place from the lower to the higher grades of or-
ganisms, which is likewise exhibited in the system of
the present vegetal and animal world; and that in many
ways embryonic development as well as metamorphosis
and heterogenesis,—in a word, individual development
(“ Ontogenesis,” Haeckel) suggests a comparison with
these palzontological series, as well as with the sys-
tematic order of succession. The parallelism of the
palzontological and the systematic series is either a mir-
acle, or it may be accounted for by the doctrine of
Descent. There is no other alternative. And the doc-
trine of Descent fully bears the test; it shows how the
derivation of the present organisms from those pre-
viously existing rests on the transmission of the char-
acters of the progenitors to the offspring and the ac-
quisitions of the individuals. The phenomena of indi-
vidual development or Ontogenesis admit of no other
choice; either they remain incomprehensive, or they

195
196 ‘THE DOCTRINE OF DESCENT.

stand the test of the doctrine of Descent and submit to
the great general principle.

If we scrutinize the countless facts of reproduction and
development, they certainly admit of classification; they
range themselves in analogous and homologous groups;
types of development become apparent; we speak of
development without metamorphosis, of transformation,
and heterogenesis. But what necessary relation the al-
ternating forms, the shapes appearing in heterogenesis,
bear to the complete animal or the sexually developed
chief representative of the species? why so many animals
undergo no transformations, but emerge ‘ complete”
from the egg? why the species belonging to the same
class or “type” possess the same type of development
and process of construction?—these and similar questions
as to the interpretation of the tangled mass of facts press
themselves upon us. And they are also tests of our
theory of derivation. The doctrine does as much as has
been done by any great hypothesis in its special appli-
cation; and if it gives a satisfactory reply to all, or at
least to nearly all, pertinent questions, these are so many
witnesses and proofs of its truth, which, according to all
scientific custom and justice and philosophic method,
will remain valid until the falsity of the inductions and
inferences has been demonstrated and a better hypothesis
substituted in its stead.

The first proposition derived from the doctrine of
Descent in explanation of the facts of individual de-
velopment may run thus: accordance in the outlines
of development is based on similar derivation; or,
somewhat differently stated: accordance in the out-
lines of individual development is accounted for by
DEVELOPMENT OF ECHINODERMS. 197

similarity of derivation. As we already know, C. E. v.
Baer first demonstrated that the members of the great
divisions of the animal kingdom agreeing in the out-
lines of their organization testify their coherence by a
special “type of development.” This fact was always
looked upon as self-evident, although, if it were not de-
rived from descent, it would be the greatest miracle.
This is therefore the place for us to review some of the
fundamental forms of development which we partially
considered in the third chapter, and at the same time
to elucidate the meaning of these types with the aid of
the doctrine of derivation.

We will take the Echinoderm as our first example.
Although from the anatomical comparison of a crinoid,
a star-fish, a sea-urchin, and a sea-cucumber or
holothuria, the close kindred of these various divisions
of echinoderms is easily deduced, they yet deviate won-
derfully from one another in outward shape and in the
construction of the skeleton. The relative value of the
difference between a holothuria and a star-fish, a sea-
urchin and a comatula, may be compared to the differ-
ence between a mammal and a bird, an amphibian and a
fish. Nevertheless, with some few exceptions which have
a special meaning, these various echinoderms leave the
egg ina larval state almost identical. The larva (Fig. 12)
is boat-like in form, with a curved lt iy
margin bent over at both ends like a ‘Y=
deck. This border is edged with a
continuous row of cilia, by the agency
of which the little boat is moved. A
short digestive canal, provided with
a gastric enlargement, is the first essential organ of this

   
198 THE DOCTRINE OF DESCENT.

body. We will not describe the highly complex trans-
formations of the larva here into an ophiura, there into
a sea-urchin, and here again into a sea-cucumber; but we
will only inquire what can be the cause of this accord-
ance in the earlier stages of individual development.
There is no reasonable answer but the derivation of all
echinoderms known to us from an older form, in the
development of which our larva likewise appeared, and
from which this common phase of development was
transmitted to the whole family. But it is allowable
to ask, further, how from a bilateral larva, one, that is,
symmetric on two sides, should be evolved in animals
of radiate structure, as are the greater number of mature
echinoderms?

On this point Haeckel instituted a conjecture which
at first exasperated the systematizers of the old school,
but which now gains more and more footing, and is
supported by the most recent comparative investigations,
such as those of Hoffmann “On the Minute Anatomy
of the Starfish” (“ Ueber die feinere Anatomie der See-
sterne”). The boat-shaped larva of the Echinoderms,
especially a modification occurring in the star-fish, strik-
ingly resembles a certain larval type of the marine
Annelida. And as in the structure and distribution of
the parts of the rays of the echinoderms, especially of
the star-fish, an unmistakable resemblance with the rela-
tive distribution and succession of parts of the
Annelids is observable, Haeckel regards the Echinoderms
as an offshoot of the Annelids. He corisiders that the
oldest, and to us unknown, echinoderms originated as
annelid stems; the anterior end of the bilateral annulose
parent-animal budding out gemmules in a radiate ar-
DEVELOPMENT OF MOLLUSCS. 199

rangement. This gemmation, or, in other words, this
stem structure, still occurs in Echinoderms, inasmuch as
some species of star-fish possess such powers of repro-
duction as to enable a single arm or ray, when torn off, to
complete itself into a whole animal. Nay, Kowalewsky’s
observations render it highly probable that the separa-
tion of rays, and their completion by gemmation, is in
some species a normal process. Haeckel’s hypothesis is
thus laughed at only by those who are afraid to think or
reason.

In the family of the Mollusca, the so-called navicula
larva testifies the kinship of at least two of the great
classes. The third and most advanced class, that of the
cuttle-fish, had perhaps lost their distinctive badge even
in those primzeval times when, under the somewhat lower
forms of the Tetrabranchiata, they left their shells in
the Silurian strata. But the bivalve shells, or Lamelli-
branchiata, and the snails, widely differing in anatomical
development, and constituting two natural classes, have
a common larval form, or, if the larvz display different
shapes, a highly distinctive common larval organ, the
velum. The accompanying diagram gives on the right
the navicula of a cockle-shell as seen from behind. At
the anterior end, two fleshy lobes have been formed,
edged with cilia, by the vibrations of which the young
animal, even in the egg, performs spiral twisting mo-
tions; in the midst of the cilia rises a little prominence,
furnished with a longer filament. These ciliated lobes or.
vela, merging into one another, are shown on the left in
the larva of a sea-snail (Pterotrachea), as seen nearly in
profile, and in the phase in which the eyes and auditory
apparatus, the foot and operculum, as well as a delicate

14
200 -THE DOCTRINE OF DESCENT.

shell, have made their appearance. Here also, from the
plane of the velum, a small fleshy protuberance juts out,
without any special purport. The distribution of the
velum, the period at which this larval organ makes its

 

FIG. 13.

appearance, its position towards the testa, head, mouth,
and foot, and its subsequent effacement, one and all co-
incide exactly in the two classes. It is as yet of only
a relatively small number of marine shells and slugs
that we know the evolutionary history; yet we may infer
that in these animals remaining in their original home,
this heirloom has been generally preserved. Even gen-
era which in their mature state scarcely recall the type of
the Mollusca, as the boring mollusks (Dentalium Tere-
do), have preserved the phase of the navicula. On the
other hand, in the branchiate fresh-water snails (Paludina)
the velum is little developed, and in the land snails, which
differ most widely from their marine kindred, the velum
is entirely obliterated, as it is also among fresh-water
mussels. If in these animals adaptation and migration
to land has had this effect on embryonic and post-
embryonic development, we must suppose that in
OTHER FORMS OF DEVELOPMENT. 201

the Cephalopoda, notwithstanding their continued so-
journ in salt water, other causes have produced the loss
of the velum phase, and the course of development pe-
‘culiar to it.

With respect to the other fundamental forms of de-
velopment, we may refer to the third chapter. The con-
struction of the higher Articulata points to annulose pro-
genitors, more or less corresponding to the annelids of
present times; and, again, the gradual increase of the
segments of the larval annelids, which may be compared
to the process of gemmation, leads from these higher
Vermes to the lower ones with unsegmented bodies. All
vertebrate animals, man included, if they do not pre-
serve through life an unsegmented vertebral column, not
separable into single vertebre, are raised as embryos
from this condition into their higher and definitive
phase. The fact that they pass through this common
embryonic condition excludes all other mechanical causes
but that of a common derivation from primordial forms
which possessed an unsegmented vertebral column, no
cranium or an imperfect one, and either no brain or one
little differentiated from the spinal cord. Karl Ernst
v. Baer, who, while we write these pages, raises his voice
against the doctrine of Descent, has established the fact
of types of development, and the course, within these
types, from the undifferentiated to the special; but by
the words “type of development,” the fact is para-
phrased, not explained; and, as we cannot repeat too
often, we prefer the distinct idea of derivation to the
supposition of an unknown higher Power manifesting
itself after an incomprehensible fashion in the types of
development.
202 THE DOCTRINE OF DESCENT.

If the concatenation of the series by direct derivation
and heredity be disallowed, it is absolutely inconceiv-
able‘ why the supreme creative Power, Nature, or the
personal God, should have bound all higher animals to
the same common stages of early development, and here-
by exposed them to such manifold purposeless arrange-
ments and great dangers. Of the millions of young
oysters which annually escape from the egg, the ma-
jority perish under the disadvantages of external condi-
tions, because the oyster has not yet divested itself of
the ancient heirloom of the roving navicula. It has been
able to compete successfully in the struggle for existence,
only because, like most of its congeners, it is enormously
prolific. This may be understood; but that a personal
Creator, merely on principle, in order to keep the oyster
within the type of development, should have. endowed it
with the phase of the navicula, in this case so extremely
unpractical, can be accepted, like much other nonsense,
only as matter of faith.

If accordance in the outlines of development has gen-
erally shown itself derivable from similarity of descent,
we may now proceed to the explanation of those phe-
nomena of development known to us as heterogenesis
and metamorphosis. In these, the historical stages of
development of whole classes and orders are inherited
in the development of the individual; a proposition which
is merely the corollary and application of what has been
already intimated. The Hydromedure offer numbers of
such instances of heterogenesis, of which Gegenbaur’s
early views gives the following account: We have already
(p. 43) become acquainted with the origin of the
Cladonema from the polype-like Stauridium. The
ALTERNATION OF GENERATIONS. 203

Medusa is the sexually mature form of the cycle
of the species; its ova develope into polypes, which
constitute the intermediate form in their develop-
ment; that is to say, it is not transformed into the

 

FIG, 14.

animal from which it is derived, but produces gemmules.
Only in this generation does the species revert to the
sexual form.

We shall understand this alternation of generations
if we begin with the simplest Medusa polypes. Such
a one is the annexed Hydractinea carnea, of which
the female individual is portrayed. Compared with
the intermediate form, Stauridium, the preliminary
phase of the Cladonema, reproducing itself asexually,
204 THE DOCTRINE OF DESCENT.

the Hydractinea seems superior, inasmuch as it is itself
a sexual form. The zone of spherical protuberances in
the middle of the body are the ovaries or egg capsules
corresponding to the sperm capsules of the male indi-
vidual. Heterogenesis does not take place in our Hy-
dractinia, but, as in the development
of the ovum of the Cladonema into the
Stauridium, there is a transformation
of a ciliated lava into a sessile polype.
But it is obvious that the part which
in the Hydractinia is played, by the
male and female sexual organs is per-
formed in the generative cycle of the
Cladonema by the sexual animals. By
following the transition from the de-
pendent organ into the independent
animal, we find the solution and ex-
planation of the process termed he-
terogenesis. Between the genera reproduced like the
Hydractinia, and those reproduced like the Cladonema,
there are many others, of which the propagation shows
the gradual transition of the rudimentary sexual organs
into the sexual animal. We may so arrange the genera
of the “ Medusa polypes” as to exhibit how the parts
which in the Hydractinia are mere capsules, generating
and enclosing the ova, become more and more perfect.
They acquire a special branch of the alimentary canal
and blood-vessels, and are provided with the marginal
papilla characteristic of the Medusz, and constituting
their peculiar sensory organs. In short, what in one
member of the systematic series may be termed an or-
gan, is, in the next, the Medusa separating itself and

 

FIG. 15.
PARASITIC WORMS. 205

becoming a new generation; the sexual organ has be-
come the sexual animal.

Now as the individual development of the Cladonema,
and other Meduse similarly propagated, corresponds
with the systematic series of the Medusa polypes, the
only reasonable and creditable explanation of the onto-
genesis of those Medusz in which heterogenesis occurs,
is that, in them, the historical development of the genus
has become fixed. Neither the egg nor the hen was
created. Before the delicately tinted Medusze populated
the primzeval ocean in lonely splendour, the Medusa.
polypes on the constantly changing shores were the sole
representatives of the still infant class. Another and.
very reasonable view is that which Weismann’s latest re-
searches tend to support: That polypes were indeed the
precursors of the Medusz; that individual polypes (not:
merely organs) became Medusz, and that the im-
perfectly developed intermediate forms were degener-
ate Medusa, degraded to the condition of apparently
mere organs.

The evolutionary history of the intestinal worms leads
to the same reflections and results. These animals, widely.
differing in their structure, were either created in or
with their hosts, or else they have become habituated
to them in a natural and direct manner. We may surely
disregard the third alternative, that they were led by
an innate “ obscure impulse.” According to our doctrine,
the worms now passing the whole or a portion of their
lives as parasites on or in other organisms, are descended
from free and independent animals, and the periods oc-
curring in their development, during which parasitic life
is exchanged for independent phases, signifies a rever-
206 THE DOCTRINE OF DESCENT.

sion taking place systematically in all individuals to the
once permanent condition of their progenitors. Of the
Trematoda or Flukes, and Cestoda or Tapeworms, be-
‘longing to the class of the Platelmintha Suctoria, the
latter have diverged the most from their starting-point;
their adaptation to life within other animals has rendered
the alimentary canal superfluous, and their generations
and transformations hence point less to their progenitors
than is the case with a number of other Trematoda, with
which many anatomical characters prove them to be
closely related. Both, moreover, share the characters of
their class with the free-living Turbellaria. From such
as these, that is to say, from forms approximate to the
present Turbellaria, the Trematoda and Cestoda must
be descended, and with this agrees the free roving phase
which the larva of the Fluke (Distomum) undergoes as
the so-called Cercaria, and previously as a rotating spher-
ical body.

Many of the ciliated Nematoids, or thread-worms,
too,—the division which includes the Ascarides among
others,—have in their infancy a stage of independent
life, during which they cannot be distinguished from
the infantine forms of their more numerous kindred,
which never adopt a parasitic life, and chiefly inhabit
the sea. The transition to parasitism, as recapitulated
by ontogenesis, was nothing more than an extension
to a new territory offering advantages of nutriment;
and on this point it is highly instructive to compare
the Nematodes with the systematic series of the leech-
like Suctoria (Trematoda), so excellently described
by Van Beneden. We here find all the transitions
from independent predatory genera to others occasion-
PARASITIC CRUSTACEA. 207

ally parasitic, and again from these to others which on
leaving the egg immediately attach themselves for life.
Here, as elsewhere, parasitism seems an adaptation to
new habitats, which is recorded in the biography of the
individual with a reminiscence of the previous form.
The circumstances of the parasitic worms are repeated
by the parasitic Crustacea, as, moreover, a probably
primordial form of the crab family is preserved in
the metamorphoses of several orders of this large and
diversified, though coherent class. The larva, which,
it may safely be assumed,
approximates closely to
the primordial form, was
at one time taken for an
independent genus and re-
ceived the name of Nau-
plius. Hence a Nauplius
phase is spoken of, which
obtains especially among
the lower Crustacea, the
Copepoda, parasitical Crus-
tacea and Cirripedes, and
the remarkable Rhizopoda connected with them; but
is not wanting in the highest order, the decapodous
stalk-eyed crab. We shall later have to make ac-
quaintance with the so-called curtailed development which
among the crabs has been adopted by the decapods, and
it was formerly supposed by all. Were this actually
the case, we should still, by analogy, infer their connec-
tion with the other orders repeating the Nauplius phase
in the course of their development; but it was a welcome
discovery of Fritz Miiller’s that a shrimp (Peneus) still

 

FIG, 16,
208 THE DOCTRINE OF DESCENT.

begins its development as a Nauplius; whereas all the
other members of the order, as far as they are known,.
leave the egg in the higher Zoea phase (p. 50). As of
the hundreds of stalk-eyed crabs, scarcely a dozen have
been hitherto examined as to their development, it will
not be doubted that, with regard to the Nauplius phase,
some resemble the Peneus of the Brazilian coast. But

 

Fic. 17, Axolotl,

even were this case to prove unique in the order, it
would suffice as a living witness of the connection be-
tween the presence of the decapods and the primordial
crabs. There can be no other view of this subject. The
Nauplius phase in the development of the Peneus is either
a shining testimony in favour of the doctrine of Descent,
or a senseless paradox.

After what has gone before, the transformation of the
AMPHIBIANS. 209

Amphibians needs no elucidation. Their predecessors
were water-breathers, whose form and mode of life are
more faithfully preserved by the long-tailed Amphibians,
the tritons, and salamanders, than by the frogs. In
our tritons, sexual maturity not rarely commences in
the larval state, hence in a phase which was definitive
in the progenitors of the present genera. There is, in-
deed, one species, the Mexican Axolotl, which normally
propagates itself during the larval phase. Auguste
Dumeril’s observation is highly interesting, that of the

 

FIG. 18,—Amblystoma.

thousands of Axolotls that he bred at Paris, some few
advanced beyond the grade of development hitherto
known in them, #.e. they lost their gills, changed the
shape of their bodies not inconsiderably, and from gill-
210 THE DOCTRINE OF DESCENT.

breathers, and aquatic animals became lung-breathers
and terrestrial animals. It needs further observation to
ascertain whether (what is, however, very improbable), in
their home, all Axolotls, after having propagated them-
selves in their larval state, undergo the_ metamorphosis
into salamander-like animals (Amblystoma), or whether
the transfer to Europe and the consequent entire change
of the circumstances of life gave the impulse to a pro-
gressive transformation of these few individuals, which,
by the continuance of these conditions, would in future
generations extend to more and more individuals, and
finally become the characteristic of a new species.

The examples of Ontogenesis, or individual develop-
ment, hitherto examined, had the peculiarity that the
sexual animal does not issue directly from its egg like
the Phoenix from its ashes, but had to pass through
various forms and existences in which the progenitors
of the species again become alive and palpable. We
must now inquire how this development is related to that
form of reproduction which the systematizers, completely
in accordance with the facts, yet without any correspond-
ing meaning, have termed “direct development,” or
“development without heterogenesis or metamorpho-
sis?” The ciliated embryos of many Medusz are not
converted into polype-like intermediate forms, but pass
directly into Medusz. The greater number of higher
crabs do not leave the egg as Nauplia, but as more or
less perfect decapods. The bird, the mammal, and man
are all at birth “similar to their parents.” Consider-
ing that the processes of heterogenesis are in themselves
by no means advantageous to or “in harmony with
design ”—we have only to remember the fate of the tape-
DIRECT DEVELOPMENT. 211

worm’s eggs—that by the larval state the period of in-
fancy and weakness is prolonged, and the period of ma-
turity and efficient care for the continuance of the species
delayed, it follows that curtailments and reductions, con-
sequent on adaptation have, ‘as advantageous modifica-
tions, a prospect of perpetuation. As in Amphibians the
prolongation of the larval phase may be effected by
natural circumstances and artificial experiments, so in
like manner a compression of the phases of transforma-
tion, and a general curtailment of the metamorphosis
is imaginable. In the class of Amphibians we have, in
fact, several examples of curtailed and modified meta-
morphosis which bridge over the apparent chasm be-
tween development with and without transformation, and
render direct development comprehensible as being
gradually acquired. Amphibians will endeavour to ex-
tend themselves wherever they are invited by a sufficient
supply of insects, and the black salamander of the moun-
tains (Salamandra atra) has even overcome the impedi-
ment which might have been deemed insurmountable,
the absence of water for its larvee. It does not lay its eggs
like its congeners, but only two are received into the
oviduct, and the fluids secreted from its walls replace the
marsh to them and to the larve which emerge from
them. Here, and not when separated from the parent,
do the gills make their appearance, while the other eggs,
gradually following, are devoured by the hungry larve.
The metamorphosis of the black salamander, which has
lately been the subject of Fr. Marie Chauvin’s remark-
able experiments, can be effected after exclusion, and
observation places it beyond a doubt that this is an in-
stance of adaptation to unusual conditions. . If the mode
212 THE DOCTRINE OF DESCENT.

of life of the marsupial frog, which carries its young
in a membranous fold of the back, and the Surinam
toad, of which the larve live singly in the chambers
of a kind of honeycomb on the back, were better known
than they are, we should assuredly arrive at the same
results as with the black salamander. In the absence
of other knowledge, the observations of M. Bavey,
Marine Pharmaceutist at Guadaloupe, first published in
1873, are of the highest importance.** A trog of those
parts (Hylodon Martinicensis) goes through its whole
metamorphosis in the egg. In the egg it has gills and
tail; and from the brief remark that the island con-
tains only rapid running streams, and nowhere stag-
nant waters or marshes, it appears that this is also
a case in which adaptation modifies and curtails devel-
opment.

If, after this introduction, we now examine the so-
called direct development with more attention, it may
in every way be compared to the metamorphosis of the
Hylodes of Guadaloupe. Direct development is a trans-
formation in the ovum; and in the cases in which it oc-
curs, the phases of embryonic development are repeti-
tions, more or less distinct, of the historic development
of the family. We will only particularize in the embry-
onic life of the Vertebrata (in which metamorphosis does
not take place), some phases that are stages of curtailed
transformation, and recapitulate the permanent condi-
tion of their progenitors. It has been repeatedly men-
tioned that in all vertebrate animals, the vertebral column
is first laid out as an unsegmented cord and an unseg-
mented sheath for the spinal cord. This is the permanent
state of the lower fishes. In the higher Vertebrata also,
DEVELOPMENT OF AMMONITES. 213

the brain at first consists of vesicles, lying one behind
the other, which is the persistent form of the lower
groups. The embryonic heart of mammals and birds
begins in the form of a tube, and subsequently ac-
‘quires the communications between the chambers,
which in the reptiles never close. In the Amphibians,
the branchial arches really bear gills during the lar-
val state. They are not wanting in the embryos: of
reptiles, birds, and mammals, any more than the
fissures through which, in fish and the larve of
Amphibians, the water passes off after being inhaled.
Must we again set forth the only possible explanation
of these facts?

Before referring to the phenomena which testify the
emanation of families from a common root, we will cite
one of the most important evidences of recent times,
which traces the genesis of species through a great
geological period, and exhibits in detail the relations
of the development of the individuals to that of the
species, -genus, and family. We mean L. Wiirten-
berger’s contribution to the geological evidence of the
Darwinian theory, to which we have already appealed
‘(p. 97). It relates to the two families of Ammonites, the
Planulata and Armata; of which, according to Wiirten-
berger’s researches, the latter are developed from the
former, as the ribs of the Planulata gradually pass into
the spines of the Armata. Of special interest to us are
the following passages of the preliminary communication
on the discoveries obtained from thousands of specimens,
and which will probably not be made public, with all the
vouchers, for some years to come. “It gave me particu-
lar pleasure,” says Wiirtenberger, ‘‘ when, after divers
214 THE DOCTRINE OF DESCENT.

careful comparative studies, I at last detected an inter-
esting and simple conformity to law in the variations of
the Ammonites. Namely, on the first appearance of a
modification which subsequently attains essential im-
portance in an entire group, it is only slightly indicated on
a portion of the last convolution. Towards more recent
deposits, this modification is more and more plainly
shown, and then advances, following the spiral course of
the shell; that is to say, it gradually takes possession of

 

FIG. 19.—Ammonites Humphresianus. A form analogous to the Planulata.

the central turns also, as we trace the forms to higher
strata. This reproduction in younger stages of life of
modifications first occurring at a more advanced age,
makes but slow progress, so that we see the older forms
repeated with great persistency in the central turns. Fre-
quently a modification of this sort has taken possession
of only a small part of the convolutions, when a new
one already appears at the outside, and follows the
first. Thus searching through the strata from below
DEVELOPMENT OF AMMONITES. 215

upwards, we see modification after modification begin-
ning at the outer part of the Ammonites, and advancing
towards the centre of the discs. The innermost convo-
lutions often resist these innovations with great per-
sistency, so that we usually find upon their surface sev-
eral of these states of development in close juxta-position,
as the shell of the individual Ammonite begins with
the old morphological type, and then adopts the modifi-
cations in the same order in which they follow in vast
periods in the geological development of the groups con-
cerned.”

“The Ammonites,” he says moreover, “thus obtain
at an advanced and maturer age—only when they have
gone through the development inherited from their
parents, and as much as possible in the same manner as
their parents—the power of modifying themselves in a
new direction, that is to say, of adapting themselves to
new conditions; yet these modifications may then be:
transmitted to the offspring, so as to appear in each
subsequent generation a trifle earlier, until this phase of
development in its turn characterizes the greater portion
of the period of growth. But this last. and longest.
phase of development scarcely ever suffers itself to be
supplanted by new ones, formed in like manner; heredity
operates so powerfully, that a period of development thus
once predominant, is repeated in the infancy of the
Ammonites, even though but slightly indicated. Hence
in an individual Ammonite from a recent stratum, the
periods of development compressed and forced back
upon the innermost convolutions, must appear in the
same succession in which they. wrested the dominion

from one another. It is extremely interesting to study
15
216 THE DOCTRINE OF DESCENT.

the development of the Inflata of the upper white Jura
(which follow the Ammonites liparus, whose externally
visible convolutions display only one row of spines),
carefully breaking off convolution by convolution.
Towards the middle there is a region in which there are
always two rows of spines; nearer the centre the inner-
most row disappears; soon afterwards the outer one also;
and the nucleus, some millimetres in diameter, now ap-
‘pears for about half a turn as a Planulatum, with dis-
tinct ribs, which, towards the beginning, likewise disap-
pear. Thus even the Planulate ribs, which prevailed
among the Liassic ancestors of these Inflata, and were
supplanted by the spines as early as in the brown Jura,
still distinguish these later and essentially modified de-
scendants during a short period of their youth.”

Wiurtenberger further shows how
these relations can be simply ex-
plained by the Darwinian theory
alone; “without it we should have
only an extraordinary problem.”

It was natural to test the applica-
bility of the theory of selection also
on the forms alliedto the Ammonites,
such as the Ancyloceras; namely, the
genera in which the convolutions do
not touch and partially conceal one
another, as in genuine Ammonites,
and which, as late comers and side

L shoots of the group, seemed des-
FIG. 20.—Ancyloceras. —_ tined to decay. Selection and decay?
Wirtenberger shows how the abandonment of contact
in the convolutions was to the spinous Ammonites .an

  
FORMS ALLIED TO AMMONITES. 217

advantage which would be established by selection. If
other paleontologists consider the fluctuations of form
accompanying the relaxation of the closed spiral as evinc-
ing the decline of the group, no contradiction seems to
be implied, for what was originally used as an ad-
vantage by natural selection, proved injurious in its con-
sequences.

As we have seen, the earliest states are obliterated to

 
    
  
   
  
  

WN
»
(of

00

i
Ty-4

e

SS
i

=a

FIG. 21.

such a degree by curtailment of development that the
indication of the nature of the progenitors continually
diminishes. But our theory necessarily leads to the
conviction that the families within which we have as yet
been able to compare Ontogenesis with Phylogenesis,
constantly approximate in their origin, and vindicate the
218 THE DOCTRINE OF DESCENT.

expectation that at least here and there, in the indi-
vidual development of single representatives of the vari-
ous families, witnesses of their common derivation should
come to light. This likewise occurs, and to such a de-
gree that in the earliest larval stages a link is estab-
lished between the lowest and the highest animals. If
a number of groups of the lowest living beings, in which
the various vital functions of nutrition, irritability, mo-
tion, and reproduction are supplied by amorphous proto-
plasm,—if these be separated, as by Haeckel, into a
neutral kingdom, owing to the absence of sexual repro-
duction, we must likewise agree with him in attributing
to the Spongiadz ranking next to the Protista, the name
of animals, on account of their sexual propagation and
the nature of their embryonic development and first larval
phases.

Haeckel has bestowed on one larval stage of the
calcareous sponges the title of Gastrula, wherein the
animal represents a sac, or, in other words, a stomach
provided with a mouth-like orifice. The walls are
formed of two rows of cells, the outer one consisting of
ciliated cells; that is to say, each cell is furnished with
a long filament. At the orifice of the sac, the outer row
merges into the inner one, and from these two mem-
branes the body of the sponge is constructed in a definite
manner. Now, if this Gastrula larva reappears in the
Coelenterata, Polypes, and Medusz, in which the gradual
development from the two membranes, the entoderm
and ectoderm, into the most complex forms has long
been known; and if, as Haeckel has further shown, the
osculum, or larger opening of the spongiadz may be
closely compared with the mouth of the polype and
GERMINAL MEMBRANES. 219

medusa, and the great central cavity of the sponge with
the stomach of the others, of the canal system with
the canals and cavities of the Ccelenterata,—then, in
combination with the host of other facts, implying and
supporting the doctrine of Descent, the inference is in-
evitable that in the Gastrula we have a testimony of the
consanguinity of the Spongiade and Ccelenterata. But
this Gastrula reappears in the Holothuria; hence in the
Echinoderms, in the Sagitta, in the Ascidians, which
will be more narrowly examined in the pedigree of the
Vertebrata, and finally in the Lancelet; and we, there-
fore, hold ourselves justified in regarding this coinci-
dence of the earliest states of development in different
families, as the remnant of the common root, which in
other families, as in the Articulata, for example, has been
lost in the curtailment of development. The significance
of the “germinal membranes” in the Vertebrata was
recognized even by Pander, and in the suggestive works
of v. Baer; the extension and application of this observa-
tion to the whole animal kingdom, for which we are
especially indebted to Kowalewsky, marks one of. the
greatest advances in the science of comparative develop-
ment.

The reader unacquainted with the detailed researches
of our science, has already been called upon to observe
that there are opponents of the theory of selection, such
as Owen, who nevertheless accept the doctrine of Descent
as incontestable. Even rejecting natural selection, the
parellelism of Ontogenesis with Phylogenesis may also
be brought into the natural connection maintained by
us, on the assumption of an unnatural or supernatural
guidance which converts this apparently natural unity
220 THE DOCTRINE OF DESCENT.

into a miracle. Quite recently, A. Braun has pointed out
the accordance of the botanical system, and therewith
of paleontological succession, with the development of
the individual plant, when he says: *7—‘In the further
elaboration of the natural system, the gradation of the
vegetal kingdom, and, at the same time, the relation of
the system to the history of development, becomes more
and more spontaneously and incontrovertibly manifest.
The Acotyledons are verified as Cryptogams, as they
were already considered by the old botanists of pre-
Linnen times, and their relation to the Phzenogams is
thus more clearly pronounced. The Cryptogams are
separated into two essentially different divisions, in which
gradation is likewise distinctly pronounced (cellular and
vascular Cryptogams, Thallophytes and Kormophytes);
between the perfect Phaenogams and the Cryptogams
an intermediate grade has been shown, that of the Gym-
nosperms. But most important of all is the circumstance
that the four chief grades ascertained in the vegetal king-
dom accurately correspond with the grades of develop-
ment occurring in the individuals of all the higher plants;
—the germ, the vegetative stem, the blossom and the
fruit.” But why this parallelism is to be most important
of all, if it is not to lead us to the knowledge of true
causality, is beyond our comprehension. We can well
imagine that the “inherent causes” and the “ Principle
of Perfection” may be welcomed as the refugium ig-
norantie, but not that they can really satisfy inquiry. For
our own standpoint, the accordance oftheresults of botan-
ical investigation must be extremely important, but it
is for the palpable reason that the theory thereby gains the
support and corroboration of another great series of facts.
THE BEGINNING OF LIFE. 221

If the accordance of the evolution of families has
once been followed up to the Gastrula, we shall not pause
there, but must regard the similarity of the sperm cor-
puscules and germ cells from the Spongiadz to the Ver-
tebrata as a primordial common property, connecting
the animal and vegetal world; and prior to the acquisi-
tion of which, only those modes of reproduction took
place which have been maintained among Protista and in
heterogenesis.

As the common basis of sexual reproduction in the
various families argues a common origin, asexual re-
production, directly connected as we have seen it to be
with sexual propagation, by means of unfecundated eggs
and germs, leads us constantly further towards the be-
ginning of life. But the cell furnished with a nucleus
and sheath is inseparable from the protoplasmic cor-
puscule devoid of nucleus or sheath, on the growth and
fission of which rests the reproduction of the lowest liv-
ing beings.

Their origin from inorganic matter, as we have set
forth above, is a postulate of sound human understand-
ing. To this beginning we are led, not, as the opponents
of the doctrine of Descent are wont to say, by a dog-
matic after-philosophy, but by the unprejudiced consid-
eration and computation of the facts of individual devel-
opment.*®
222 THE DOCTRINE OF DESCENT.

X.

The Geographical Distribution of Animals in the light of the Doctrine
of Derivation.

ALTHOUGH ever since the century of the great geo-
graphical discoveries, material has been accumulating
for a geography of plants and animals, the foundations
of scientific botanical geography (apart from George
Forster’s observations) were first contained in Hum-
boldt’s celebrated “ Ideas on the Physiognomy of Plants”
(Ideen zu einer Physiognomik der Gewachse). It is the
first description of vegetal forms, comprising the entire
area of the earth, and the manner in which, singly or
combined, they lend a characteristic impress to the land-
scape of their region of distribution, and again on their
side harmonize with the other factors of the scene. The
celebrated founder of Climatology, who circled the ter-
restrial globe with lines of equal temperature, of equal
inclination and declination of the magnetic needle, and
divided it into dry and rainy zones, knew better than
any of his contemporaries that the animal and vegetal
world depended on all these factors. Yet neither he
nor his followers, before Darwin, rose higher than the
description of Nature, which had already checked Buffon
in his grand picture of Nature, “Les Epoques de la
Nature.”

A natural result of the extraordinary extension of
VICARIOUS FORMS. 223

the geographical horizon and the profundity of special
research was the more careful ascertainment of .the
regions of distribution of animal and vegetal families,
and of their more prominent species, in which, as we
have already said, either no questions were asked as to
the causes of distribution, or the matter was facilitated,
as by Louis Agassiz, who did not, like Linnzus, derive
each species from a pair, but supposed them to be cre-
ated in suitable numbers of individuals in their own
regions of distribution. It cannot be expected that any
solution was hereby given to the questions which now
force themselves upon us, such as why, under like natural
conditions, like species are not always to be found, and
conversely? Why very similar species frequently appear
under external conditions entirely dissimilar? What is
to be thought of the mutual relations of the so-called
vicarious forms? &c.

As Riitimeyer has recently observed, in his excellent
treatise “On the Derivation of the Animal World of
Switzerland ” (“ Ueber die Herkunft der schweizerischen
Thierwelt ” *°), Buffon had already remarked the repeti-
tion of the African in the American fauna; how, for ex-
ample, the lama is a juvenescent and feeble copy of the
camel; and how the puma of the New represents the
lion of the Old World. Still, by the mere word “ repre-
sentative” or “vicarious form” nothing is gained, and
a true apprehension of these facts is obtained singly and
solely if we meet the inquiry with the assumption that
camel and lama, puma and lion, are of common deriva-
tion, and that their diverse development was in the lapse
of time favoured and determined by the separation of
the habitats of their progenitors.
224 THE DOCTRINE OF DESCENT.

Another example of so-called vicarious or “ analo-
gous” species, affording an easier basis for induction, is
provided by the comparison of the snails of Southern
Europe, and especially of Spain, with those of North
Africa, on which we are indebted to Bourguignat for
some excellent observations. In accordance with other
botanical and zooligical facts, he has established that
the shell fauna of Spain and North Africa forms a whole,
so that the Algerian snails appear a mere appendage to
those of Southern Europe, notwithstanding the separa-
tion by the Straits of Gibraltar. Now it is proved that,
in geologically recent times, this region of North Africa
was in fact a peninsula of Spain, and that its union
with Africa was effected on the north by the rupture of
the Straits of Gibraltar, and on the south by an up-
heaval to which the Sahara owes its existence. The
shores of the former Sea of Sahara are still marked by
the shells of the same snails that live on the shores of
the Mediterranean. But all North African species are
not identical with those of Spain; of many African sorts,
only “ analogous” species are found on our side. Now
if certain Spanish species do not themselves occur in
Africa, but are yet replaced by very similar forms, our
standpoint at once connects with the otherwise unmean-
ing word “analogous” species the idea of the common
derivation of the forms replacing one another, and of
the local variations superinduced by isolation and altered
conditions.

A severe test is applied to those who believe that
species were separately created, by the air-breathing
land snails (pulmo-gasteropoda), when it is seen that in
isolated islands and island groups these earth-bound ani-
ANALOGOUS FORMS. 225

mals, migrating with so much difficulty, have attained
an extraordinary diversity. In the Madeira Islands, 134
species of pulmo-gasteropoda were reckoned about ten
years ago, of which only 21 were to be found in the
Africo-European fauna. These and the 113 other spe-
cies are mostly confined to narrow districts and single
valleys. Are we to suppose that the 113 species for
Madeira, and the 21 species for Madeira and Africa
with Europe, were each separately created? Must we
not much rather infer that a connection at one time ex-
isted between Europe and the present island group of
Madeira, and that these 21 species remained what they
were before the separation; while from unknown species
still appearing in analogous forms upon the continent
emanated the remarkable profusion of new species?
They, and their comrades on other isolated islands, were
spared a conflict many sided, and they doubtless af-
ford a favourable example of Wagner’s law of mi-
gration, as with the difficulties of locomotion, and the
improbability of a large subsequent arrival, the se-
cluded individuals, under even slightly different influ-
ences, had had a prospect of diverging from the parent
species.

The unscientific opinion, that under like, or nearly
like, ‘external conditions, like or similar organisms
were created in great numbers, receives a severe blow
by the perception that the direct reverse has frequently
occurred. Why has America no horses in the present
era, although it is proved that the horses introduced,
thrive capitally? It is not necessary for us to explain
why the fossil horses which existed in America, as well
as in the Eastern hemisphere, became extinct without
226 THE DOCTRINE OF DESCENT.

leaving any progeny—we do not know the cause,
though we may yet be able to fathom it; but in this
and all similar cases the adherents of the doctrine of
Creation must confess the inadequacy of their theory
of belief.

Our exposition has shown that the species now extant
are the progeny of organisms previously existing; the
present apportionment on the earth is therefore a con-
sequence of the distribution of the progenitors of the
present organisms, and of the manifold displacements
of land and water by which they were indirectly or di-
rectly affected. We cannot hope ever to picture to our-
selves a faithful representation of the perpetual transfor-
mations of the surface of the earth. Only, if this could
be accomplished, and if we, moreover, had an accurate
register of the animals at each period inhabiting the
former islands, continents, and oceans—only then could
the distribution of the present organisms be thoroughly
fathomed and established. But in thus acknowledging
the incompleteness of our statistical means, we are at
least able to lay down with certainty the course of in-
quiry. We must, in the first place, proceed in the
method of the older vegetal and animal geography to
ascertain the natural limits and regions of distribution;
and, secondly, to collate these facts with the facts. of
the distribution of the former progenitors of the present
animate world as it was determined by the geological
conditions of those times. It is needless to say that
Darwin has furnished the outlines for this work also.
But among his followers two are specially worthy of dis-
tinction: Wallace, with his researches on the Malay
Archipelago,” abounding in subtle observation; and
DISTRIBUTION OF ANIMALS. 227

Riitimeyer, in his treatise already cited. In what follows
we may essentially adhere to the latter.

Our knowledge of the regions of distribution of the
animal world is still extraordinarily deficient. What do
we know, for instance, of the occurrence of marine ani-
mals? Few years only have elapsed since the depths of
the sea were rendered accessible to research, and the
result has almost entirely upset our earlier notions of
the geological significance of the sea-bottom and its
habitability. After the strong impulse given by Maury
to the investigation of the physical condition of the sea,
we are now occupied in ascertaining the submarine tem-
peratures and currents, the constitution of the sea-bottom,
the occurrence of deep-sea organisms, and the conditions
of their existence. We are therefore just beginning to
collect the material for a future geography of marine
organisms. Among terrestrial animals, certain groups
of which the actual distribution can be defined, are use-
less for our general purpose.

Butterflies, for instance, which are an easy prey to
currents of air, defy geological barriers, and, above all,
that important partition which from the tertiary era has
been erected, or rather excavated in the bottom of the
sea, between Australia and India.71 It is the same with
bats, and also with migratory, predatory, and aquatic
birds; while, as Wallace shows, the other orders of this
class are in tropical regions very reliable and stable in-
habitants of their often limited districts, seemingly sug-
gestive of migration. Exclusive of these, there remains
therefore little more than the Mammalia, whose extrac-
tion may be inferred with certainty from a comparison
of their present cantonments (Cantonirung),—an expres-
228 THE DOCTRINE OF DESCENT.

sion which we borrow from Ritimeyer,—with the en-
campments of their former kindred, whence are derived
general points of view as to the causes of the present
geographical apportionment of organisms.

If in the preliminary establishment of facts we there-
fore confine ourselves to the Mammalia, exclusive of
whales and bats, a superficial survey is enough to show
that not only single species, but families also, have each
a certain region of greatest density of occurrence, a
focus of distribution, and that from thence radiations
have taken place according to the convenience and fit-
ness of the territory. Lion and tiger, elephant and
camel, range over a definite era; the monkeys of the
New World differ from those of the Old World not only
geographically, but also in family characteristics. Mar-
supials are chiefly concentrated in Australia; sloths and
armadilloes in South America. And these examples,
easy to multiply, indicate how individuals of widely dis-
persed species, and the species themselves, emanated
from single points of the earth’s surface and flowed over
the territory of distribution now occupied. When to
this observation is added the other, that in past eras
also the same groups had the same centres of distri-
bution,—for instance, Brazil not only harbours sloths
and armadilloes now, but was once peopled by more
numerous and partly colossal species of these families,
and Australia has furnished the most numerous and im-
portant fossil remains of Marsupials,—the cognizance of
this persistent localization becomes very significant, and
we account for the “repetition” of these forms by de-
rivation.

Now if the centres of distribution, at the first glance
ORIGIN OF ISLANDS. 229

extremely numerous, can be brought into closer union
and reduced to the smallest number possible, as by our
theory the Mammalia have but one point of derivation,
and if we can herewith harmonize the geological succes-
sion of the organisms examined, or, in other words,
harmonize the horizontal distribution with the vertical
or historical sequence, animal geography will then ap-
proach the solution of its task. Wallace and Ritimeyer’s
works are therefore an important advance, as the former
has given detailed evidence that the fauna of the com-
plex and extensive Australio-Indian Archipelago is by
no means self-dependent, but consists merely of off-
shoots of the continents; and the latter, in a grand sur-
vey of the entire surface of the earth, has reduced the
centres of distribution to the simplest proportions as yet
possible.

The comparison of insular and continental faunas is
naturally of great interest. For should it appear that,
with respect to the animal world, islands are one and all
mere appendages of the continents, the problem would
at once be vastly simplified. If we follow Peschel’s
luminous exposition of the origin of islands,’? we have
first to deal with the fragments of continents. A great
number of islands, such as Great Britain and the great
Asiatic islands, may be recognized at once as fragments
of still existing continents. On the other hand, Mada-
gascar and the Seychelles are not, as might be con-
jectured, a segment of Africa, but the remnant of a
former continent very peculiar in its flora and fauna.
Other islands originate either from submarine volcanoes
or from corals, and in the latter case the structure is
founded on sinking land. It naturally follows that on
230 THE DOCTRINE OF DESCENT.

volcanic and coral islands only such animals will be en-
countered as reached them by swimming or flying. The
presence of Mammals pre-supposes human agency or
extraordinary accidents. The older the islands, the
richer are they ini organisms. Islands detached from
continents will, on the contrary, be rich in proportion
as they are recent, of which Great Britain bears witness.
The more divergent is their fauna, the longer must be
the time which has elapsed since their separation. Thus,
for instance, we may view the relations of Tasmania
and Australia; and if New Zealand was ever connected
with the old Australian continent, the separation oc-
curred at an epoch so remote that it throws no light upon
the physiognomy of the animal world of New Zealand,
and vice versa.

In the account of his travels in the Malay Archipel-
ago, Wallace has given a pattern of animal-geographical
research. Years before, G. Windsor Earl had pointed
out that the great islands of Sumatra, Borneo, and Java,
are connected with the Asiatic continent by a shallower
sea; while a similar shallow sea assigns New Guinea
and several adjacent islands to Australia, with which
they have a common characteristic in the Marsupials.
Wallace has defined this partition more minutely with
a line marked by a deeper submergence of the sea-bot-
tom. It is drawn below the Philippine Islands, and,
having Celebes to the south, passes through the straits
of Macassar and separates the two small islands of
Bali and Lombok. We will now follow Wallace’s
description (“Malay Archipelago”), with various omis-
sions.

“Tt is now generally admitted that the present dis-
MALAY ARCHIPELAGO. 231

tribution of living things on the surface of the earth is
mainly the result of the last series of changes that it has
undergone. Geology teaches us that the surface of the
land and the distribution of land and water is every-
where slowly changing. It further teaches us that the
forms of life which inhabit that surface have, during
every period of which we possess any record, been also
slowly changing. As to the Malay Archipelago, we find
that all the wide expanse of sea which divides Java,
Sumatra, and Borneo from each other, and from Malacca
and Siam, is so shallow that ships can anchor in any
part of it, since it rarely exceeds forty fathoms in depth:
‘and if we go as far as the line of a hundred fathoms,
‘we shall include the Philippine Islands and Bali, east of
Java. If, therefore, these islands have been separated
from each other and the continent, by subsidence of the
intervening tracts of land, we should conclude that the
separation has been comparatively recent, since the
depth to which the land has subsided is so small.—But
it is when we examine the zoology of these countries
that we find what we most require—evidence of a very
striking character that these great islands must have
once formed a part of the continent, and could only have
been separated at a very recent geological epoch. The
elephant and tapir of Sumatra and Borneo, the rhi-
noceros of Sumatra and the allied species of Java, the
wild cattle of Borneo and the kind long supposed to be
peculiar to Java, are now all known to inhabit some part
or other of Southern Asia. None of these large ani-
mals could possibly have passed over the arms of the
sea which now separate these countries, and their presence

plainly indicates that a land communication must have
16
232 THE DOCTRINE OF DESCENT.

existed since the origin of the species. Among the
smaller mammals, a considerable portion are common
to each island and the continent; but the vast physical
changes that must have occurred during the breaking up
and subsidence of such extensive regions have led to the
extinction of some in one or more of the islands, and
in some cases there seems also to have beén time for a
change of species to have taken place. Birds and insects
illustrate the same view, for every family, and almost
every genus of these groups found in any of the islands,
occurs also on the Asiatic continent, and in a great num-
ber of cases the spccies are exactly identical. Birds of-
fer us one of the best means of determining the law
of distribution; for though at first sight it would appear
that the watery boundaries which keep out the land quad-
rupeds could be easily passed over by birds, yet prac-
tically it is not so; for if we leave out the aquatic tribes
which are pre-eminently wanderers, it is found that the
others (and especially the passeres, or true perching
birds, which form the vast majority) are generally as
strictly limited by straits and arms of the sea as are
quadrupeds themselves. As an instance, among the
islands of which I am now speaking, it is a remarkable
fact that Java possesses numerous birds which never pass
over to Sumatra, though they are separated by a strait
only fifteen miles wide, and with islands in mid-channel.
Java, in fact, possesses more birds and insects peculiar to
itself than either Sumatra or Borneo, and this would
indicate that it was earliest separated from the con-
tinent; next in organic individuality is Borneo; while
Sumatra is so nearly identical in all its animal forms
with the peninsula of Malacca, that we may safely
MALAY ARCHIPELAGO. 233

conclude it to have been the most recently dismembered
island.

“The Philippine Islands agree in many respects with
Asia and the other islands, but present some anomalies
to indicate that they were separated at an earlier period,
and have since been subject to many revolutions in their
physical geography. ,

“Turning our attention now to the remaining portion
of the Archipelago, we shall find that all the islands,
from Celebes to Lombock eastward, exhibit almost as
close a resemblance to Australia and New Guinea as the
Western Islands do to Asia. It is well known that the
natural productions of Australia differ from those of Asia
more than those of any of the four ancient quarters of
the world differ from each other. Australia, in fact,
stands alone; it possesses no apes or monkeys, no cats
or tigers, wolves, bears, or hyenas, no deer or antelopes,
sheep or oxen, no elephant, horse, squirrel or rabbit;
none, in short, of those familiar types of quadruped which
are met with in every other part of the world. Instead
of these, it has Marsupials only, kangaroos and opossums,
wombats and the duck-billed platypus. In birds it is
almost as peculiar. It has no woodpeckers and no
pheasants, families which exist in every other part of
the world; but instead of them it has the mound-making
brush-turkeys, the honeysuckers, the cockatoos, and the
brush-tongued lories, which are found nowhere else upon
the globe. All these striking peculiarities are found also
in those islands which form the Austro-Malayan division
of the Archipelago.

“The great contrast between the two divisions of the
Archipelago is nowhere so abruptly exhibited as on
234 THE DOCTRINE OF DESCENT.

passing from the island of Bali to that of Lombock,
where the two regions are in closest proximity. In Bali
we have barbets, fruit-thrushes, and woodpeckers; on
passing over to Lombock these are seen no more, but
we have abundance of cockatoos, honeysuckers, and
brush-turkeys, which are equally unknown in Bali or in
any island further west. The strait is here fifteen miles
wide, so that we may pass in two hours from one great
division of the earth to another, differing as essentially
in their animal life as Europe does from America.* Ii
we travel from Java or Borneo to Celebes or the Moluc-
cas, the difference is still more striking. In the first,
the forests abound in monkeys of many kinds, wild cats,
deer, civets and others, and numerous varieties of squir-
rels are constantly met with. In the latter, none of these
occur, but the prehensile-tailed cuscus is almost the only
terrestrial mammal seen, except wild pigs, which are
found in all the islands, and deer (which have probably
been recently introduced) in the Celebes and the Moluc-.
cas. The birds which are most abundant in the Western
islands are woodpeckers, barbets, trogons, fruit-thrushes,
and leaf-thrushes; they are seen daily, and form the great
ornithological features of the country. In the Eastern
islands these are absolutely unknown, honeysuckers and
small lories being the most common birds; so that the
naturalist feels himself in a new world, and can hardly
realize that he had passed from the one region to the other
in a few days, without ever being out of sight of land.
“The inference that we must draw from these facts
is undoubtedly that the whole of the islands eastwards,

* This is to vaguely expressed. It would be nearer the mark to say,
as Europe does from South America. (O. SCHMIDT.)
FORMER PACIFIC CONTINENT. 235

beyond Java and Borneo, do essentially form a part of a
former Australian or Pacific continent, although some of
them may never have been actually joined to it. This
continent must have been broken up not only before the
Western islands were separated from Asia, but proba-
bly before the extreme south-eastern portion of Asia
was raised above the waters of the ocean; for a great
part of the land of Borneo and Java is known to be
geologically of quite recent formation; while the very
great difference of species, and in many cases of genera
also, between the productions of the Eastern Malay
islands and Australia, as well as the great depth of the
sea now separating them, all point to a comparatively
long period of isolation.”

“Jt is interesting to observe among the islands them-
selves how a shallow sea always intimates a recent land
connection. The Aru islands, Maisol and Waigiou, as
well as Jobic, agree with New Guinea in their species of
mammalia and birds much more closely than they do
with the Moluccas, and we find that they are all united to
New Guinea by a shallow sea. In fact, the 1oo-fathom
line round New Guinea marks out accurately the range
of the true Paradise birds.

“Tt is further to be noted—and this is a very interest-
ing point in connection with theories of the dependence
of special forms of life on external conditions—that this
division of the Archipelago into two regions character-
ized by a striking diversity in their natural productions,
does not in any way correspond to the main physical or
climatal divisions,of the surface.” We will further quote
only the following: ‘Borneo and New Guinea, as
alike physically as two distinct countries can be, are
236 THE DOCTRINE OF DESCENT.

zoologically wide as the poles asunder; while Australia,
with its dry winds, its open plains, its stony deserts, and
its temperate climate, yet produces birds and quadru-
peds which are closely related to those inhabiting the
hot, damp, luxuriant forests which everywhere clothe the
plains and mountains of New Guinea.”

Wallace gives the most specific proofs that, as the
parts of this Archipelago approach one another like sepa-
rated extremities of two continents, they bring with them
two entirely different fauna. Similarly, the Mediter-
ranean and West Indian Archipelagos are devoid of any
peculiar character, and are completely dependent on the
adjacent continents for their animal life and vegetation.
We have already discussed Madeira and its land snails.
Insular faunas therefore do not require the hypothesis
of more centres of creation than are offered by the
continents; and Rttimeyer has endeavoured to trace
the extraction of birds and mammals to two centres of
derivation. A great series of animal-geographical facts
is explicable only on the hypothesis of the former ex-
istence of a southern continent, of which the Australian
mainland is a remnant. The present Marsupials are
concentrated in Australia. Their occurrence in the
south-western portion of the Malay Archipelago, includ-
ing New Guinea, seems like a radiation from that
centre. No single token makes it appear that the
Marsupials existing in former periods in the northern
hemisphere, from the Jura forwards, had migrated to
meet those which were pressing on from the southern
continent towards the equator. Only as to the oppossum,
so widely extended in South America, could a question
arise, which is however solved by the examination of a
1

SOUTHERN FAUNA. 237

host of congeners, one and all alien to the population
predominant in America, and indicating importation —
probably in the Tertiary period; unless it be assumed,
with Rtitimeyer, ‘that implacental mammals were cre-
ated out of Australia as well as in it.”

Among the first to be mentioned are the wingless
birds, that is, those which are anatomically and syste-
matically connected, and which we now find scattered
over continents and some of the larger islands. The
cassowary of New Holland and America, the extinct
giant birds of Madagascar and New Zealand, the
African ostrich, which has advanced from the south
northwards, cannot have originated in their present
isolation. The same considerations are forced upon
us by the mammals named Bruta by Linneus, and
by modern zoologists termed Edentata, by reason of
their imperfect dentition, among which, accepting the
latter definition, must be included the Ornithorhyncus,
or duck-mole of Tasmania. These duck-moles incon-
testibly occupy the lowest grade among the mammals
now extant; but the other true Edentata are no less alien
to the higher orders, and their occurrence in South Amer-
ica on the one hand, and in South Africa and South Asia
on the other, as well as ‘the impossibility of tracing them
from a common centre in the northern hemisphere, points
to the vanished land of the south, where perhaps the
home of the progenitors of the Maki of Madagascar may
also be looked for.

“Or,” says Rtitimeyer, “does the hypothesis of a
Polar land, once possessing an abundance of animal life,
partly covered by the ocean and partly by a coat of ice,
appear an unfounded assumption to us who now witness
238 THE DOCTRINE OF DESCENT

the elevation of a similar frozen surface in the northern
hemisphere, and are surrounded in the Alps by a still
existing—in our glacial drift by a scarcely vanished—
arctic scene? Or need the conjecture that the almost
exclusively graminivorous and insectivorous Marsupials,
sloths, armadilloes, ant-eaters, and ostriches, once pos-
sessed an actual point of union in a southern continent,
of which the present flora of Terra del Fuego, the Cape,
and Australia, must be the remains,—need this conjec-
ture raise difficulties at a moment when from their fossil
remains Heer restores to our sight the ancient forests of
Smith’s Sound and Spitzbergen? ”

Having ventured to reconstruct the southern conti-
nent, with its strange fauna, of which the remains are
so widely dispersed, Riitimeyer casts about for more
specific evidence in favour of the hypothesis to which
the course of the world’s formation everywhere gives
rise, that fresh-water animals and likewise terrestrial ani-
mals came up from the sea. Hence the notably small
division of sirenoid fish (Lepidosiren, Protopterus), which
breathe air during the dry season of the year, must not
be considered reptiles adapting themselves to aquatic
life, but the reverse. The organ which in fish served
as a hydrostatic apparatus, the swim bladders, becomes
in them the lung. Thus we must go back from terres-
trial to aquatic tortoises, and from them to those deni-
zens of the sea which are allied to the Enaliosaurians,
so frequent in the Jurassic strata. The evolutionary
and biographical history of the land crabs shows us in
the plainest manner how the inhabitant of the sea be-
comes a terrestrial animal; a special problem which, as
we have already mentioned, Fritz Miller has completely
MODIFICATION OF FISHES. 239

solved and capitalized, in his essay, “for Darwin.” Of
the sirens, commonly but erroneously reckoned among
the Cetacea, and of which the majority prefer remain-
ing at the mouths of large estuaries, one entire species
has penetrated into the great inland lakes of Africa; and
certain species of salmon as well as the sturgeons, which
alternate periodically between salt and fresh water, are
in the phase of gradually forsaking ocean life. From
my special experience, I may add that the brackish water
sponges are certainly dependent on the marine families,
and that the fresh-water species unmistakably point to
these brackish forms.

If in all these cases we are dealing with gradual trans-
formation, and more or less voluntary adaptation, there
is no lack of conspicuous instances of forcible and almost
sudden severance; of upheavals by which former sections
of the ocean became inland seas. What were the modi-
fications undergone by the fish and crabs secluded with
them, is shown by the-fine observations of Lovén on the
animals of Lakes Wener and Wetter, and of Malmgren
on those of Ladoga. The latter brings evidence that the
salmon-trout of the Alps (Salmo salvelinus) is derived
from the Polar Sea, and is own brother to the Scan-
dinavian Salmo alpinus.

Riitimeyer pronounces the opinion that by more
minutely tracing the relations of the fresh-water fauna
to those of the denizens of the ocean, the cosmopoli-
tanism of fresh-water animals will be explained, as well
as the relation of antarctic to arctic life. For the present,
however, these two great animal-groups, as regards the
higher, warm-blooded classes, are somewhat sharply con-
trasted. It is only from scanty remains that we know
240 THE DOCTRINE OF DESCENT.

that so early as the Jurassic era, the northern hemisphere
was peopled by Marsupials, but, it is evident, not densely.
We must suppose that, retaining their character, the Mar-
supials of the southern continent tested and proved their
powers of adaptation, whereas on the other side of the
equator a race of mammals of completely different cast
proceeded from them. This is the race which still char-
acterizes the whole surface of the earth from the north
to the point of contact with the more stable remnants
of antarctic life. While with reference to their origin we
can appeal only to reason and inference, the historical
connection between the mammalia now peopling the Old
and the greater part of the New World, and their pred-
ecessors up to the most ancient Tertiary periods, is
manifest to our eyes.

The remains of the earliest mammals here to be con-
sidered, are found in the Eocene deposits of Switzerland,
and in corresponding strata in France and the south of
England. From the southern edge of the Jurassic
plateau, neither the Alps nor any other land was visible,
and the ocean which washed its shores has been traced
as far as China. The mammalia of this period, as far as
they are known, amount, according to the synopsis made
by Ritimeyer in 1867, to at least 70 species. The ma-
jority are ungulate, therefore Graminivora; of these, by
far the greater number Pachydermata. Now, when the
entire world scarcely maintains so many Pachyderms,
the proportions are quite altered. In Europe, the pig
alone represents this division, and Ruminants everywhere
predominate. In its present animal population, Africa
might be approximately compared to Eocene Europe.
But as to these Ungulates must be added a large num-
TERTIARY FAUNA. 241

ber of Carnivora, resembling the Viverrida (polecats,
martens, &c.) and hyenas, and as viverride exist in Af
rica as well as in Asia, and as, moreover, the musk
ruminants represented in this primitive fauna are now
likewise Asiatic and African, and, finally, as the French
opossums of those ages still live in Central and South
America, “we gain an impression that the most
ancient Tertiary fauna of Europe is the source of a
truly continental animal society now represented in the
tropical zone of both worlds, but most emphatically in
Africa.”

Far more heterogeneous is the picture of the higher
animal life of the middle and more recent Tertiary
periods which we reconstruct from the numerous and in
parts highly prolific repositories of these remains. To
draw narrower limits within these periods is impractica-
ble; from place to place, from stratum to stratum, there
is coherence; nowhere does a species appear that might
not be derived from another; and our authority says that
anatomy, morphology, paleontology, and geographical
distribution, seemed to impress no doctrine upon him
with such energy and pertinacity as that separate species
of a genus, species without any historical and therefore
without any previous local link to any original stock,
do not exist. The most celebrated repository of Ter-
tiary mammals is Pikermi, a short distance from Athens,
an accumulation of skeletons complete and in fragments,
which pre-supposes a profusion of animals, of which at
any rate the most densely inhabited regions of Africa
may, according to Livingstone’s descriptions, give us
an idea.

Again the Carnivora give way to the Graminivora,
242 THE DOCTRINE OF DESCENT.

though the feline beasts of prey make themselves con-
spicuous; and among the great Tertiary beasts of prey
are some which have a range as great as the tiger of the
present age. The territory of the extinct sabre-toothed
tiger (Machairodus) at that time extended over a great
part of America and Europe. Let us also mention that
the canine animals appear somewhat later, and that the
bears are of still more recent origin. At this period the
most abundant material still favours the ungulates.
Cloven feet still preponderate. Pigs and musk-animals
are the most constant. But the tapir, in shape like the
older forms, is now joined by the rhinoceros, the true
horses, and the elephants. If the origin of the rhinoceros
is somewhat obscure, the extraction of the mastodon, the
older form of the elephant, is hitherto quite unknown.”
And yet though we search in vain through the known
mammalian fauna of the Eocene period for the most
nearly allied parent forms, there are numerous tokens
that even in Europe and Asia, “the most of the Eocene
must be regarded as the true root forms of the Miocene
genera.” (R.) This is shown by the discoveries at
Nebraska in North America, where important genera,
which, like the Palzotherium, disappeared from the Old
World in the Eocene period, took refuge in company
with newer genera. We likewise find there, intermediate
forms between the lama and the camel, which in this
case alone gives its true significance to the once unmean-
ing word, vicarious genera. At Nebraska we moreover
find the triple-hoofed horse (Anchitherium), and we hence
know the origin of the single-hoofed horse of the Old
and New Worlds.

What has happened in the Old World since that age
DISTRIBUTION OF ANIMALS IN AMERICA. 243

is confined to the extinction of many Pachydermata, a
displacement of the rhinoceros, elephant, tapir, and hip-
popotamus, and an extremely abundant development of
the true ruminants and the cattle which proceeded from
them with an exaggerated form of head. Bears and
canine species occupy the territory where viverride and
hyenas once predominated; but as ‘“ numerous locally
and historically limited species, a large number—among
the smaller fauna a majority—of Miocene races remain in
possession of the ancient and probably constantly increas-
ing habitat.” (R.) “In this gradual change of things,
no one will be able to discern aught but phenomena of
the same order of which we are still the witnesses.” (R.)

How circumstances occurred in America has been
described in a masterly style by Riitimeyer as follows:
“ America affords a basis for the distribution of animals
completely different from that of the Old World. In
the latter, ridges, open only in places, divide the entire
continent into mountainous zones, and correspond to
the distribution of temperature. Thus in a twofold
manner they prescribe a definite range east and west
to the extension of animals; while a migration from
north to south is impeded less by the height of the
mountains than that on their summit the north comes
into contact with the scorching south. Behind this wall,
moreover, in the expanse from the Caspian Sea to China,
there is a zone of steppes and deserts which fences in
the animals more effectually than the mountain chains.
In America, not beasts of prey alone, but graminivora
also, may advance without hindrance from the regions
of the lichen on the Mackenzie River, through the pine
forests of Lake Superior, to the land of the magnolia
244 THE DOCTRINE OF DESCENT.

in Mexico; 40°—50° of latitude separate the extremes
which meet in the Himalayas, and the vast plains and
huge river systems seem almost to solicit immigra-
tion. The accordance of the whole faunas of Mex-
ico and Guiana, moreover, shows how little the isthmus
of Panama checks the advance to South America,
where again one mighty fluvial system trenches upon
the other without any lofty partitions; nor is there any
arid desert in the whole extent from the Canadian seas
to Patagonia.

“We shall probably not be wrong in ascribing the
remarkable extension of fossil and present mammals of
America in a great measure to this circumstance. As
we have seen, the Miocene fauna of Nebraska is the
offspring of the Eocene fauna of the Old World. The
Pliocene animals of Niobrara, which are buried in the
same district as Nebraska, but on more recent arenaceous
strata, still further corroborate this statement: elephants,
tapirs, and many species of horses, scarcely differ from
those of the Old World; the pigs, judging by their
dentition, are descendants of European miocene
Paleochceride. The ruminants are represented by the
same genera, and partially by the same species, as in
the analogous strata of Europe, as deer, sheep, and buf-
faloes; neither do the carnivora or the minute animal
life offer an exception. Many genera of an entirely
Old-World cast have in the lapse of time penetrated far
into South America, and there died out shortly before
the arrival of man, or perhaps by his co-operation, as
was the case with the two species of mammoth of the
Cordilleras and the South American horse, whose present
successors reached this insular continent by a far shorter
DISTRIBUTION OF ANIMALS IN AMERICA. 2,45

road. Even a species of antelope and two other horned
ruminants (Leptotherium) found their way to Brazil. Two
sorts of tapir, of which the dentition, even in Cuvier’s
eyes, is scarcely distinguishable from the Indian species;
two species of pigs, still bearing in their milk-teeth un-
mistakable characters of their aboriginal form; and a
number of deer, besides the lamas, a later and originally
American offshoot of the Eocene Anoplotheria—are one
and all living remnants of this ancient colony from the
East, which did not reach its dwelling-place without
copious losses on its long pilgrimage. It can scarcely
be doubted that many of the beasts of prey which in the
Diluvium of South America retained their family charac-
ter more than they do now, must have arrived there in
the same manner. Let us now remember that even the
Eocene Czenopithecus of Egerkingen distinctly pointed
to the present apes of America, and that the Didelphidze
(Opossums) lie buried in the same European soils. It
might almost appear that it was pre-eminently the di-
vision of arboreal quadrumana which, with the opos-
sums, domesticated itself in the vast forests, of their new
abode, and, receiving a fresh impulse, gave rise to a
multitude of special forms, without however having, even
in the present times, reached the pitch of development
attained by their cousins who had remained behind in the
Old World.

“We may now appropriately return to our previous
remark that this migration of animals did not find the
south of the New World destitute of mammals, but rather
already occupied by the toothless representatives of ant-
arctic, or at least of southern animal life. The diluvial
fauna of South America collected by Lund, Castlenau,

\
246 THE DOCTRINE OF DESCENT.

and Weddell, from the Brazilian caves, and the alluvium
of the Pampas, among the 118 species cited, actualiy
includes, in addition to those already mentioned, as be-
ing of probably Old-World pedigree, no less than 35
species of Edentata, and these animals of consider-
able bulk. Not reckoning the 36 rodents and bats, and
the smaller fauna in general, they constitute nearly half
of the larger diluvial animals of South America. The
assemblage of Edentata previously settled in these
regions thus held their own against the invasion from
the north.

“Tt is comprehensible that the same external causes
which led the march of the children of the north con-
stantly further, may likewise have invited the members
of the antarctic fauna to extend themselves northwards.
As we even now encounter the incongruous forms of
the sloth, the armadillo, and the ant-eater in Guatemala
and Mexico, in the midst of a fauna in great part con-
sisting of races still represented in Europe, we also find,
even in diluvial eras, gigantic sloths and armadillos rang-
ing far into the north. Megalonyx Jeffersoni, and Mylo-
don Harlemi, sentries of South American origin thrown
out as far as Kentucky and Missouri, are a phenomenon
as heterogeneous in the land of the bison and the deer, as
is the mastodon in the Andes of New Granada and Bo-
livia. Over the whole enormous extent of both portions
of the New Continent, the mixture and interpenetration
of two mammalian groups of completely diverse families,
constitutes the most conspicuous feature of its fauna; and
it is significant that each group increases in the abundance
of its representatives and in the originality of their ap-
pearance as we approach its point of derivation.”
CAUSES OF GEOGRAPHICAL DISTRIBUTION. 2,47

Hence, on both sides of the ocean, north of the very
sinuous boundary of the antarctic or southern fauna,
we find ourselves still in the midst of the diluvial animal
world, which extended itself, by a bridge in the vicinity
of the North Pole, from the old continents to the
mainland of America, and there for a longer period re-
tained its ancient appearance in the mastodons and
horses.

There, as well as here, the present order of things—
the cantonment of animals—has been in many ways de-
termined and modified by mighty glacifications and pro-
longed periods of refrigeration. Hence the accordance
of so many plants of the extreme north with Alpine
plants after the Eocene vegetation had made its entry
from the east. Since that age, the reindeer has been
forced back to the north, and the musk ox has been
expelled and exterminated from the Old World. The
elephants, fleeing before the ice, have not returned; and
the mammoth, immigrating with a rhinoceros from the
north-east, has been destroyed with his associate. Others
of his comrades, such as the primeval ox, died out only
a few centuries ago as wild cattle; others, like the buf-
falo and the beaver, are nearly extinct as denizens of
Europe; and others again, the deer and roe-deer, will
perish with the forests and the game-laws. But of al-
most all the species of which we search for the extrac-
tion, Paleontology supplies us with the history and de-
rivation; and in derivation we find the causes of geo-
graphical distribution sketched in vivid outlines.
248 THE DOCTRINE OF DESCENT.

XI.

The Pedigree of Vertebrate Animals.

THE final result towards which the doctrine of Descent
directs its efforts, is the pedigree of organisms. To
work it out is to collect the almost inconceivable pro-
fusion of facts accumulated in the course of about a
century by descriptive botany and zoology, including
comparative anatomy and the history of development
and to submit the existing special hypotheses to a minute
scrutiny and renewed verification. We have therefore
claimed in behalf of the doctrine of Derivation the priv-
ilege on which the progress of science generally relies—
that of investigating according to determined points of
view, and accepting probabilities as truth in the garb of
scientific conjecture or hypothesis. It is manifest that
when the doctrine of Descent first made its appearance
with the arguments proposed by Darwin, it was only
possible to indicate the most general outlines of this great
pedigree, which it was the special task of the new di-
rection of science to demonstrate in all its details. But
however and wherever specific research was attempted,
either the results contributed the form of some part of
the great pedigree, or there was, from the first, reason
to pre-suppose certain kinships, and the conjecture was
PEDIGREE OF VERTEBRATE ANIMALS. 249

tested. The further an inquirer has carried his sur-
vey of the conditions of organization in any of the
larger groups, the less will he be able to divest
himself of the genealogical idea in his every act and
thought.

All this is so self-evident, that one would scarcely sup-
pose that the use of this method could have been made
a subject of reproach to the doctrine of Descent. Never-
theless, it frequently occurs, and the champions of the
doctrine of Descent are blamed for often speaking of
mere probabilities, forgetting that even in cases in which
the probability ultimately proves false, the refuted hy-
pothesis has led to progress. Of this the science of lan-
guage has recently borne testimony. It is well known
that linguistic comparison within the family of Indo-
Germanic tongues suggested the reconstruction of the
primitive language which formed: their common basis.
Johannes Schmidt ™* now proves that the fundamental
forms disclosed may have originated at widely different
periods, and hence that the primitive language, regarded
as a whole, is a scientific fiction. Nevertheless, inquiry
was essentially facilitated by this fiction, and with it
was intimately connected the formation of a pedigree
of the Indo-Germanic linguistic family, as a hypothesis
supported by many indications. A bifurcation was as-
sumed into a South European language, with Greek,
Italian, and Celtic ramifications, and another language,
from a second division of which proceeded the funda-
mental language of North Europe and the Aryan fun-
damental language. Although Johannes Schmidt has
demonstrated that this pedigree is false, as the existence
of Slavo-Lettish shows the impossibility of the first di-
250 THE DOCTRINE OF DESCENT.

vision assumed, the value of the hypothesis is undimin-
ished. It was the road to truth.

In our science Haeckel has made the most_extensive
use of the right of devising hypothetical pedigrees as
landmarks for research. It matters nothing that he has
repeatedly been obliged to correct himself, or that others
have frequently corrected him; the influence of these
pedigrees on the progress of the zoology of Descent is
manifest to all who survey the field of science, not to
mention that in the last ten years a series of researches
have conclusively fixed their results in good pedigrees.
As we propose to give merely an introduction to the
doctrine of Descent, we shall content ourselves with
showing how the system or the pedigree is constituted
in its application to the single group of the Vertebrata.

 

 

 

Mammals.
Birds.
Reptiles,
k SS
Amniota.
? Enaliosaurians. Amphibians,
ae
| Amphioxus.
oa
a Testacea,
epee monet

Primordial Vertebrata.

Annulosa.

As we have seen above, the most important indica-
tions of the pedigree of the species are contained in the

'
PEDIGREE OF VERTEBRATE ANIMALS. 251

evolutionary history of the individual. But though all
vertebrate animals testified their family connection by
agreeing iter se in the distribution of the germ as well
as in the fundamental important organs, the spinal cord
and the veretebral column, every token of their descent
from inferior animals, which is unconditionally demanded
by the theory, seemed to be entirely wanting. In other
words, it seemed that in all vertebrate animals the mem-
ory of their original derivation had been obliterated by
curtailed development (comp. p. 211). Thus the case
remained until Kowalewsky a few years ago studied the
development of the lancelet (Amphioxus), the lowest
vertebrate animal known, and showed that in this crea-
ture the typical phenomena of vertebrate development

 

FIG. 22,—Larva of the Lancelet after Kowalewsky.

are preceded by the phases required by the theory. We
have already made acquaintance with this form of de-
velopment (p. 51, &c.), and we here again. point out its
profound significance. It is only when the Amphioxus
has passed through the phase of the vibrating, sac-like
252 THE DOCTRINE OF DESCENT.

gastrula larva that the future dorsal side becomes flat-
tened, and the protuberances arise, which shortly after
close into the sheath of the spinal marrow, while beneath
it originates this important cellular column, the chorda
dorsalis, or notochord. With this the lancelet becomes
a vertebrate animal, and the preceding phases do not
(according to the view at one time inculcated by C. E.
v. Baer respecting such phenomena) recail the inferior
and undeveloped in general by the absence of differ-
entiation, but they agree in genesis and distribution, in
the differentiation of their cellular layers, and in their
totality, with the Gastrula phases of invertebrate ani-
mals.

We are therefore fully justified in regarding these
first incidents in the evolution of the Amphioxus as a
reminiscerice of the roots of the pedigree of the Verte-
brata; and this direct indication of the descent of verte-
brate from invertebrate animals is supported by a second
and no less important discovery by the Russian natural-
ist. It is, that during their development a number of
the Tunicata of the division of the Ascidians temporarily
possess a spinal cord, and the rudiments of a vertebral
column. Kowalewsky’s researches have been ratified
on all essential points and in many ways extended by
Kupfer, and the facts which interest us may be explained
by the diagram, Fig: 23, representing the forepart of the
larva of an Ascidian in a somewhat advanced stage.
The bulk of the Ascidian larva consists of a body of which
our figure shows the whole, and a rudder-like tail. The
appendages projecting from the body on the right are
organs of adhesion, by means of which the larva fixes
itself for its definitive transformation. At o the orifice
PEDIGREE OF,VERTEBRATE ANIMALS. 253

of the mouth is formed; d developes into the branchial
cavities and the intestinal canal, and we will incidentally

 

remark that in the lancelet also, the anterior end of the
254 THE DOCTRINE OF. DESCENT.

primitive intestine becomes the branchial cavity. But
with reference to the vertebrate animals, the most im-
portant parts of the Ascidian larva are the following.
“It possesses a true spinal cord with a vesicularly ex-
panded brain (ra). The distribution and position of
this organ agrees accurately with the corresponding
parts of the vertebrate animal, and Kupfer has even
discerned the rudiments of nerves (sss), which, if the
observation is confirmed, will still more incontroverti-
bly establish the homology of the organ in question with
the spinal cord of the Vertebrata and the nerves pro-
ceeding from it in pairs. But we know that it is not
the spinal cord alone, but its combination with the ver-
tebral column which constitutes the characteristic fea-
ture of the vertebrate animal. This vertebral column
the Ascidian larva likewise possesses (c) in the form
of the noto-chord, and, as in the vertebrate animal, this
embryonic vertebral column lies between the intestine and
the spinal cord. So far goes the accordance; henceforth,
the development of this part, so important to the verte-
brate animal, becomes retrogressive in the Ascidian. The
rudder-like tail, with the spinal cord contained in it,
and the noto-chrord, are cast off when the animal be-
comes fixed; the larval brain which promised so well,
shrink into an insignificant nervous ganglion, and the
complete animal gives no cause for suspecting its analogy
with the Vertebrata.

These laborious observations prove that the Verte-
brata are not the sole proprietors of the spinal cord and
vertebral column, but received these organs as a heritage
from lower grades of organization as their progenitors.
It does not occur to the Darwinists to regard man as the
LOWEST VERTEBRATE ANIMALS. 255

direct offspring of the present apes; neither do they
infer from these observations on the Ascidian larva that
vertebrate animals are descended from the Ascidians.
Their accordance much rather forces us to assume an
unknown primordial vertebrate family, springing from
some branch of the heterogeneous
division of the Annulosa. From
these diverged on one side the Tes-
tacea, who might perhaps be called
mischanced vertebrata, and on the
other the true vertebrate animals.”

The Amphioxus which lives in the
sand in shallow places on various
coasts, and is daily caught by thou-
sands at Messina for example, is five
or six centimetres in length, and is
compressed after the manner of a
fish, pointed at both ends, and semi-
transparent whilst alive. It pos-
sesses no trace of limbs, at the posterior end only a pair
of minute membranous margins, the indication of dorsal
and caudal fins, and is so simple in its internal structure
that it is usually, though inaccurately, termed a fish. Its
skeleton is limited to the noto-chord, and some minute
cartilaginous rods at the mouth and gills. It has no
brain, and, except a small ciliated sac, perhaps to be in-
terpreted as an olfactory organ, no sensory apparatus;
the heart is tubular. And thus between the lancelet and
other true fishes there exists so wide a difference that the
possibility remains open that the fishes passed through
some other course of development than phases like that
of the Amphioxus.

   

i

FIG. 24.—Full-grown
Ascidian,
256 THE DOCTRINE OF DESCENT.

Our knowledge of the genealogy of the fishes may
be laid down in the following diagram :—

Dipnoi.
Teleostei.

Ganoids.

Elasmobranchii.

 

Marsipobranchii.

The Marsipobranchii (Cyclostomi), it is true, exhibit
important peculiarities, such as deficiency of limbs, en-
tire absence of bony plates or scales on the integument;
but the brain, heart, and vertebral column (which, al-
though persistently cartilaginous, is far superior to that
of the Amphioxus), show their direct connection with the
fishes. Fossil remains of these animals, universally known
in the genus lamprey (Petromyzon), are not forthcom-
ing, and, at the most, only their horny teeth could have
been preserved.

After these manifest gaps in our knowledge, the suc-
ceeding orders of fishes present themselves in a connec-
tion all the more conspicuous. The starting-point is
formed by the Elasmobranchii, to which belong the true
chimeras, sharks, and rays. Brain and gills testify their
kindred with the Marsipobranchii. In the construction
of the cranium, facial bones, pectoral and pelvic arches,
and the anterior extremities, heart and intestine, they
exhibit forms to which, as Gegenbaur has shown in his
PEDIGREE OF FISHES. 257

well-known observations, the homologous parts of the
Ganoids are related either as progressive developments
or as reductions. Huxley has also prepared the way for
a correct apprehension of these relations. To be fully
convinced of this, detailed study is certainly requisite;
for in its absence it is impossible to imagine, how in the
Elasmobranchii the true branchial apparatus is wanting,
and how the cartilaginous arch, which, in them, replaces
the gills, is applied in the Ganoids, partly as the palate,
and partly as the attachment for the true lower jaw, while
the internal gills of the former, become the external gills
of the latter; how in the skeleton of the anterior ex-
tremities, a gradual simplification may be exhibited, step
by step, from the sharks and rays to the Ganoids, and
especially the sturgeon,—a process of which the two ex-
tremes are’ reached in the Teleostei on the one side and
the higher Vertebrata on the other—in the latter in the
multiform perfection of the arm and hand.

Of the Ganoids only scattered remnants survive, the
sturgeon family and some few American and African
genera, of which, as Rutimeyer says, a flight into fresh
water has been the salvation. They just suffice to ex-
plain the relation of this once extraordinarily extensive
group, to the Elasmobranchii as well as the Teleostei.

In the Teleostei, the metamorphosis of the organ-
ization of the Elasmobranchii initiated in the Ganoids,
is carried yet further. It is only with great qualifica-
tion that they can be termed ‘“ more highly developed,”
in the skeleton perhaps, to which older zoologists attrib-
uted too much importance. Brain, heart, the form of
the extremities, and the reproductive system, are indeed
distinct developments which, in combination with the
258 THE DOCTRINE OF DESCENT.

external shape and integuments, have exhibited great
powers of adaptation, but have not proved capable of
any further development. Comparative anatomy has
vainly spent much labour in attempting to trace the con-
dition of the higher animals from the special organiza-
tion of the Teleostei, or to explain the peculiarities of
the Teleostei from above downwards. It was labour lost,
for the solution is to be reached only by the method in-
dicated in the derivation of the Teleostei, through the
Ganoids, from the shark-like fishes.

Hence, at the present period, a development is con-
cluded with the Teleostei, and we must look to another
grade for the transition from the fishes to the amphibians.
We find one in the order of the mud-fishes (Dipnoi),
scantily represented by only few species (Lepidosiren
Protopterus). These fish-like animals, living in American
and African rivers which dry up in the hot season of
the year, are fish by right of their skeleton and scales,
and some other characteristics; the skull, however, al-
most resembles that of an amphibian, and they also pro-
visionally use their swim-bladdets as lungs; and by
thus breathing alternately water and air, they set before
us the transition of the gill-breathing larve of the
amphibians to the phase of air-breathing. Of the true
fishes at the present time, they most nearly approach the
family of the Crossopterygii, represented by the Af
rican Polypterus; and the discovery of a very re
markable Australian fish, the Ceratodus, confirms this
affinity.

Through forms thus resembling the Dipnoi, the ad-
vance from the fishes to the amphibians was probably
accomplished. But, as a scientific friend, profoundly
TRANSITION TO THE AMPHIBIANS. 259

versed in the history of development, has pointed out
to me,—supporting his remark on the comparison of the
respiratory organs of the Marsipobranchii with those
of the amphibians,—it is possible that frogs and sala-
manders may be directly descended from beings closely
analogous to the division of the Marsipobranchii termed
Myxine. It is to be hoped that this highly interesting
observation thay soon be made public. We gather from
the general Ontogenesis of the amphibians, that the tailed
forms are the most ancient. This is also the case with
the oldest amphibian-like animals, the Labyrinthodonts.
From their remains (Archegosaurus and others), chiefly
contained in the Carboniferous formation, we have learnt
that they had incomplete limbs or none, that their ven-
tral side was partially provided with bony plates, the
vertebral column fish-like, and that their skull, with some
of the characters of the present amphibians, combined
others which remind us partly of certain bony Ganoids,
and partly of the reptiles which subsequently appeared.
Now if in the singularly elongated snake-like Ccecilia,
which is however without tail or limbs, some peculiarities
‘of the skull of the Labyrinthodont appear again, we must
own our utter ignorance as to the actual progenitors of
this, as well as of the two other living orders of the
Ceecilia and the Batrachians. Here, therefore, we are,
as we have said, thrown entirely on the evolutionary
history of the individual. By what right we may
frame a picture with great probability approaching the
truth, the reader may have gathered from our previous
chapters.

Among the tailed amphibians, it is not only in
Ontogenesis that we see the passage from gill to lung-
260 THE DOCTRINE OF DESCENT.

breathing; the systematic series from the proteus to
the triton and the salamander, likewise exhibits this
physiological ascent, linked with various morphological
transformations, which may similarly be shown between
the ancient and modern specimens of the Labyrintho-
donts. The Batrachians, indeed, rise higher in develop-
ment than the Coecilia; but, as the friend above men-
tioned informs me, they more nearly approach the
Myxine in the construction of the internal gills of their
larva. We shall obtain a general view of the reptiles by
means of the appended diagram, in which we shall avoid
any minute systematic designations.

 

 

  

 

 

 

 

 

 

 

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PEDIGREE OF REPTILES. 261

The class presents a very comprehensive picture, al-
though only four orders now exist, of which two, the
lizards and the snakes, are scarcely to be separated. That
the snakes, which first appear in the Tertiary period, are
a direct offshoot from the lizards, is reduced to a cer-
tainty by comparative anatomy and the history of devel-
opment. In the various families of lizards we see the
absence of feet occurring in conjunction with the elonga-
tion of the body and the multiplication of the vertebre;
and the modifications peculiar to the skull of the “true”
snakes are likewise represented in the systematic series
in every gradation, beginning with the skull of the true
lizard. We cannot specify the fossil genera in which
the transformation was initiated; but in this case a doubt
would be only a capricious denial. It is otherwise with
the remaining orders, which in the beginnings, hitherto
accessible to us, exhibit diversities so decidedly marked,
that in none has it been possible to trace a direct descent
from any known member of another. Prof. Huxley, a
great authority on the anatomy of these animals, says on
this subject as follows:— ,

“Tf we ask, in what manner the earliest representatives
of these orders are distinguished from their living or
latest known representatives, we shall find, in all cases,
that the amount of difference in itself is remarkably
small in comparison with the length of time during which
the order has existed. So far as I know, there is no
fact to show that the later Plesiosauria, or Ichthyosauria,
exhibit an advance upon the earlier members of the
group. It is not clear that the Dinosauria of the wealden
and of the Cretaceous formations are more highly or-
ganized than those of the Trias; and even where a dif-
262 THE DOCTRINE OF DESCENT.

ferentiation of structure is to be observed, as in the
Lacertilia, or Crocodilia, it goes no further than a modi-
fication of the form of the articular surfaces of the verte-
bra, or of the degree to which the internal nasal aper-
tures are surrounded by bone. The osteological differ-
ences, which alone are exhibited by fossil remains, have
doubtless been accompanied by many changes in the
organization of the destructible parts of the body; but
everything tends to show that the amount of change in
the organization of reptiles since their first known ap-
pearance upon the earth, is not great in itself; and is
wholly insignificant, if we take into consideration the
lapse of time, and the changes of the surface of the
globe, which are represented by the Mesozoic and Ter-
tiary formations.

“From the point of view of the evolution hypothesis,
it is necessary to suppose that the Reptilia have all sprung
from a common stock, and I see no justification for the
supposition that the rapidity of their divergence from
this stock was greater before the epoch of the Trias than
it has been since. Consequently, seeing that the approx-
imation of the oldest known representatives of the differ-
ent orders is so slight, reptiles must have lived before
the Trias for a length of time, compared with which that
which has elapsed from the Triassic epoch until now is
small—in other words, the commencement of the ex-
istence of reptiles must be sought in a remote palzozoic
epoch.”

Comparison thus points us back to ages which afford
no record of the actual derivation of this class. Even
the Ichthyosauria and Plesiosauria, so frequently men-
tioned in conjunction, deviate widely from one another
PEDIGREE OF VERTEBRATE ANIMALS. 263

in very essential characters, which refer their supposed
common origin to a remote period. We will mention
only the fin-like extremities of the former, which are
of an obviously piscine type. We are thus thrown
back vaguely on such mixed forms as may have been
analogous to the Labyrinthodont; nay, the question
arises whether the Ichthyosauria alone, or perhaps the
Plesiosauria with them, did not diverge from the fishes
independently of the other branches of the reptile family;
an eventuality which is taken into account in the pedi-
gree at p. 250. A certain resemblance with the skull
of the tortoises (Chelonia) is exhibited by that of the
Dicynodonta. In them also the jaws, as appears from
their shape, were manifestly cased in horny sheaths; but
at the same time the upper jaw contained two huge tusks,
and it is scarcely possible to imagine a direct transition
from the Dicynodonta, appearing in the Trias, to the
more recent tortoise. In some particulars of the skall,
as well as in the situation of the posterior nasal apertures,
the forms of older crocodiles exhibit an affinity with
the lizards, from the older and unknown forms of which
they probably branched off. The winged saurians, or
Pterodactyles, may also be a branch of the lizards. They
have gained by adaptation several characters, such as
the shape and lightness of head, the length, slenderness,
and pneumatic character of the tubular bones, which
they share with the birds. But it is not in them, but
in the division comprising several families which Hux-
ley terms Ornithoscelide, or reptiles with the legs of
a bird, that we must look for the actual progenitors
of the birds. For among them one of the most im-

portant characters of the birds is, in some genera, in
18
264 THE DOCTRINE OF DESCENT.

course of preparation, so that in the full-grown animal its
origin may still be recognized; in others, as the genus
Campsognathus, it is accomplished. We allude to the
. peculiarity already discussed in p. 10, that the upper
portion of the tarsus is anchylosed with the tibia, the
lower with the metatarsus, and that the ankle-joint is
hence inserted into the tarsus.

All existing reptiles are sharply distinguished from
the Amphibians and Fishes by several phenomena ac-
companying their development. They possess two or-
gans enveloping the embryo; the amnion, which is es-
sentially a protecting sheath, and the allantois, by which
the foetal circulation, nutrition, and respiration is regu-
lated and carried on. In the Batrachians we find indi-
cations at least of the allantois, and must suppose that the
greater part of the fossil reptiles had already adopted
this advance in general organization. It implies an ad-
vance, inasmuch as animals developed by the aid of the
amnion and allantois make further progress during the
embryonic phase than is the case with the inferior Ver-
tebrata, and that they hence leave the egg with greater
powers of resistance. We must ascribe the adoption of
the amnion and allantois to remote periods of amphibian
and reptile development, for the additional reason that
the possession of their embryonic sheaths and organs
is shared by the birds which are descended from true
reptiles, and by the mammals which cannot be descended
from true reptiles.

The birds are, anatomically, so closely allied to the
reptiles, that Huxley, who has carried out the com-
parison most rigorously, has joined the two classes into a
greater systematic unit, under the name of Sauropsida,
PEDIGREE OF BIRDS. 265

or lizard-like animals. The scale of a lizard and a
feather seem to be totally different things; but in their
first rudiments they are completely identical, and the
feather has a far greater analogy with the scale, than with
the hair. The plumage, which seems to impress a spe-
cific character upon the bird, is therefore to be traced
from the formation of scales. Of the internal soft organs,
we will only remark upon the heart and lungs. All the
older geologists placed the heart of the bird on the same
level with that of the mammal and of man; in its specific
arrangements, however, it is only to be inerpreted by
the heart of the reptile, and the wind-pipe is not ramified
as in the mammal. That the reptiles exhibit a gradual
transition to the leg of the bird, has been repeatedly
pointed out. The pelvis of the bird, which is remarkable
for the length of the pubis and ischium, and is open in
front, likewise represents only a slight advance in devel-
opment upon the pelvic structure already shown in sev-
eral of the Ornithoscelide. Thus Huxley says with ref-
erence to the ischium of the Hypsilophode, that ‘ the
remarkable slenderness and prolongation of the ischium
give it a wonderfully ornithic character.” Finally, in the
skull, peculiarities possessed by the bird in contrast with
the mammal, such as the simple condyle of the occiput,
the quadrate bone, the cochlea of the auditory labyrinth,
the composition of the lower jaw, its articulation with the
skull by the intervention of the quadrate bone, &c., are
not specific characters of the bird alone, but of reptiles in
general. This similarity of type in reptiles and in birds
is perfectly manifest from the comparison of living birds
with living reptiles. But the proof that the bird is de-
rived from the reptile is rendered unimpeachable by
266 THE DOCTRINE OF DESCENT.

the discoveries, scanty as they are, of fossil intermediate
forms. The pelvis and leg of the Ornithoscelide have

Oy already been discussed. But in the
slates of Solnhofen we have more-

\ over become acquainted with the
A \\ Archzopteryx, a bird unfortu-
A nately mutilated and in many

25, impression of the tail of the
Archzopteryx Macrurus, Ow), but
exhibiting a very valuable and
. interesting intermediate stage be-
n , tween the tail of a reptile and a
I

{

|
j i AN ways damaged by pressure (Fig.
Ay
i

. | bird. Among existing birds, the
Nandu,orAmerican ostrich(Rhea),
aN \\\ | alone possesses numerous separate
: caudal vertebree; but the tail of
NNN this bird projects so little, that it
; \ in no way recalls the tail of a lizard.

lf Now the Archeopteryx exhibits a
long tail, bordered by two rows
of stiff feathers, of which the
impression remains in extraordinary preservation. The
skull of this valuable specimen, now in the British
Museuin, is so much injured, that no idea can be framed
of its construction. It is impossible to decide whether
the jaws bore teeth. The example of the tortoises
shows that within the reptile type the formation of teeth
was replaced by horny sheaths, without a correlated de-
velopment of the power of flight; the Pterodactyles,
on the other hand, combine with the power of flight a
light head, provided nevertheless with numerous teeth.

FIG, 25.
PEDIGREE OF BIRDS. 267

The obscurity which surrounded these parts of the old
antediluvian birds has been cleared up by a discovery by
the American naturalist, Marsh. He found in the upper
Chalk of Kansas the remains of two genera of birds,
which by their bi-concave vertebra remind us of the
characteristics of the ancient reptiles, and by this alone
present extremely valuable intermediate stages, but
which, moreover, bore teeth in both jaws. These teeth
are small and sharp, and were so numerous that in the
lower jaw of the animal named Ichthyornis dispar, twenty
might be counted on each side.

Thus we are now quite clear as to the kinship of the
bird. It is a reptile adapted to aerial life, and those
birds which we see more estranged from flight have ac-
quired the characters correlated with more or less in-
capacity for flight only by means of retrogression. It
fares the worse with the internal arrangement of this
class of animals. Partly from their geographical distri-
bution, partly from anatomical indications, especially of
the skull, it may be inferred that the ostrich-like birds
are not, in virtue of their strength of leg and adeptness
in running, the youngest members of their class and the
most nearly allied to the mammals, but that they are
the oldest of those now living. The nature of the
imperfection of their wings shows, as we have said, that
: they are in a state of arrest or retrogression. Beyond
this general experience it is impossible to go. If we
contemplate the bird as a flying animal, those of course
rank highest which have learnt to fly the best. This
palm avowedly accrues to the birds of prey as a whole,
although other orders are not deficient in pre-eminent
flyers. Brehm and others hold the parrots, because
268 THE DOCTRINE OF DESCENT.

of their docility, to be the highest birds. But all this
is arbitrary, and can only accidentally correspond with
the true and unknown ramification of the ornithic branch
in the pedigree of the Vertebrata.

The most ancient known remains of the Mammalia
are found in the Trias. They occur somewhat more
frequently in the central Mesozoic strata, and they all
belong to Marsupial animals. Now as Marsupials, in
comparison with the inferior classes of vertebrate ani-
mals from which they must be derived, are very highly
developed, and as in the Monotremata (Duck-mole,
Ornithorhyncus, and Porcupine ant-eater, Echidna,) we
possess mammals which are manifestly far beneath the
Marsupials, we are referred entirely to conjecture and
inference for the origin of the mammals. These point
to amphibian-like beings, in which certain peculiarities of
the mammalian skull, as the double condyle of the occi-
put, were prefigured, and which by the formation of
the amnios and allantois approached the true reptiles.
These progenitors of the Mammalia are not, however,
represented in any order of reptiles or amphibians now
extant. The pedigree (p. 269) in which we have grouped
the more accurately known fossil Mammalia with those
now living, contains considerable gaps, and rests in a
great measure on hypothesis, but it gives, never-
theless, with approximate probability a correct rep-
resentation of the consanguinity of the orders, and in
comparison with the system as it was constructed in
the school-books prior to the revival of the doctrine
of Descent, it must be esteemed a great and suggestive
advance.

As regards the structure of their skull, the constitu-
260

PEDIGREE OF MAMMALS.

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270 THE DOCTRINE OF DESCENT.

tion of the pectoral arch, and their persistence in the
phase (embryonic in other mammals) in which the rectum
and the urinary and genital ducts open into a single
cloaca, the Monotremata (Ornithorhynchus, Echidna),
limited to Australia and Tasmania, are the lowest mem-
bers of their class, and must be considered as remnants
of a division reaching from indeterminable past ages
down to the present time. It may be presumed that
the Marsupials were developed from an analogous grade.
Their powers of adaptation have been chiefly testified
in Australia, where the subdivisions of the order, usually
designated as families, are, in dentition and habits of life,
developed in a manner analogous to several of those
orders which appear on the second great scene of mam-
malian development, namely, the Northern hemisphere.

Far advanced beyond the Monotremata as to skeleton,
they remain on a low grade with respect to the repro-
ductive system, and are implacental, like the Monotre-
mata. That is to say, the embryonic blood-vessels do not
enter into those close relations with the blood-vessels of
the maternal ovary, by which the more perfect develop-
ment of other mammals within the mother’s womb is
effected. This character and the correlative formation of
the pouch in which to carry the immaturely born off-
spring, bind together the various families of Marsupials,
which deviate from one another like other orders.

With the exception, therefore, of the two orders
named, in all mammals the embrvo is attached to the ma-
ternal organism by the so-called placenta. The blood-
vessels of the developing offspring which reach the wall
of the uterus by the intervention of the allantois, form
coils and loops, between which grow similar offshoots
PEDIGREE OF MAMMALS. 271

and appendages of the blood-vessels of the ovary, so
that through the walls of the contiguous blood-vessels
an abundant exchange of fluids takes place between the
two, and therewith a prolonged nutrition and a further
and more complete development of the fcetus. The
higher character of the placental mammals, usually
plainly evinced by their anatomical relations, is thus
based on the existence of the placental mass. All inter-
mediate grades are, however, wanting which would en-
title us to infer with certainty the direct transition
from implacental to placental mammals. The Edentata,
(Bruta), manifestly the lowest of placental mammals, are
so devoid of any nearer morphological relations with
the Marsupials, that we must needs be content to as-
sume generally, on these indications, supported by
geographical distribution and geology, that they repre-
sent a very ancient branch of the placental mammals.
As we saw in the tenth chapter, they are scattered
remnants which can only by compulsion be united
into a single order. Sloths, armadilloes, ant-eaters,
differ from one another at least as much as rodents,
insectivora, and bats. The doctrine of Descent is not
discredited because it is unable to account for these
fragments of bygone animal life, but in the absence of
data it is for the time in presence of an impossi-
bility.

To ascertain the relationships of other orders, the
modern systematizers, and also the supporters of the
system of Descent, have thought fit to lay great stress
on the presence or absence of the so-called decidua.
This requires a short explanation. In many orders of
mammals, the vascular processes and villi of the wall
272 TITE DOCTRINE OF DESCENT.

of the ovary become so closely connected with the fcetal
portion of the placenta, that at birth the entire mem-
branous coating of the ovary is detached and thrown out
with it. In others, the vascular villi are not so closely
adherent; they yield without important lacerations, and
hence no deciduous membrane (Membrana decidua) is
ejected. Now, as it appears to me, the specific conditions
of the formation of the decidua have been far too little
compared to justify our inferring any close affinity from
the mere fact that portions of the coating of the ovary
are lost in parturition. Much rather it must be unre-
servedly admitted that the formation of decidua might
be occasioned by subordinate circumstances of the most
varied kinds, and hence in orders only remotely allied,
or allied merely as placental mammals. We therefore
consider the decidua to be a subordinate systematic fea-
ture where anatomical and morphological reasons are
opposed to it.

We go yet further. In the modern system the form
of the placenta is likewise employed in the grouping of
organisms. If among the Deciduata, lemurs, rodents, in-
sectivora, bats and monkeys, are classed together as or-
ders with discoidal placenta, this combination is cer-
tainly supported by a series of other reasons, and it is
quite probable that within this group of orders the form
of the placenta is due to homology, that is to Descent.
But when beasts of prey, elephants and the Daman
(Hyrax) are further cited as orders with zonary placenta,
we find ourselves in the same position as when the de-
cidua was reckoned decisive as to the closer affinity;
and we are of opinion that the subordinate form of the
placenta might similarly arise in different ways, just as it
PEDIGREE OF MAMMALS. 273

has been variously developed in the well-substantiated
division of the Ungulata. To corroborate our view by
example, we are certainly unable to make any positive
statements as to the derivation of the Proboscide. It is,
however, none the less certain that nothing positive is
implied by the customary classification by reason of their
zonary placenta. But we shall more nearly approach the
truth if we place this branch of unknown origin typically
nearer to the Ungulata than to the beasts of prey. If,
moreover, as non-deciduate mammals, the Cetacea are
held to be more closely allied to the Ungulata than to
the Carnivora, which are -deciduate,—in our eyes, this
circumstance is not decisive, as more important reasons
argue that the Cetacea were first developed from carniv-
orous genera.

In our exposition of the geographical distribution of
animals, we derived instruction from Riitimeyer with

Rhinoceroses. Tapirs. Horses.

~ Hipparion.

SQ | Macrauchenidee.

S

Anchitherium.

Paleeotheridze.

reference to the relationships of the Ungulata in
particular. In no other division do we possess such
abundant fossil material. In the older Tertiary strata
274 THE DOCTRINE OF DESCENT.

we encounter the remains of two Ungulate families, the
Palzotheride and the Anoplotheridz, essentially distin-
guished from one another by their dentition, and form-
ing the starting-points of the groups of Ungulates of
which some now appear so greatly isolated. The root to
which these two families lead back is unknown; on the
other hand, partly from the direct comparison of these
genera with the present Ungulata, partly from numerous
intermediate links found in the Miocene, Pliocene, and
Diluvium, it appears that, in the lapse of time, the separa-
tion which characterizes the present age was initiated,
and the seeming isolation was produced by the extinc-
tion of the intermediate links. It was this isolation which
induced the older systematizers to institute three orders
of Ungulata.
The special pedigree emanating from thePalxotheride
includes, among the present Ungulata, the horse, tapir,
and rhinoceros. The transi-
tion from the Palzotherium
| ff te the horse may be directly
traced, and this, moreover,
i in the two most important
characters, the dentition and
) the feet. In the Anchithe-
rium and Hipparion, the
transformation from the tri-
dactyle to the unidactyle
P v7] E Ungulate is accomplished;
FIG. 26.—Skeleton of the foot. (P) and Riitimeyer’s brilliant re-
Anchitherium. (H) Hipparion. x
(B) Hors, searches have shown how, in
the milk dentition of each
genus, the definitive dentition of the aboriginal genus

 
PEDIGREE OF MAMMALS. 275

is repeated, and Phylogenesis is unequivocally expressed
in Ontogenesis. The Anchitherium is a three-toed horse,
in which, however, the middle toe has already under-
taken the chief task. But in the Hipparion the two
side toes are entirely raised from the ground, and by
disuse are brought to the condition of arrest which is
completed in the horse.

In the constitution of the molar teeth the tapirs have
remained most faithful to the ancestral type. The cir-
cumstance that the tapir has four toes in front, whereas
the Paleotheridz known to us, have three shows, how-
ever, that the genus Palzotherium cannot have been
the ancestral stock of the tapirs. For the supposition
that the tapir acquired the fourth toe is contrary to all
experience respecting the formation of the extremities.
Rhinoceroses are also four-toed in front, and their close
kindred with the tapirs is testified by the structure of
their toes and a series of details in the skeleton.

Hippopotami. Pigs. Tragulidze. Deer. Antelopes. Oxen,

Anoplotheridee.

An isolated branch of the Palzotheride seems to be
the fossil genus Macrauchenide, which combines the
276 THE DOCTRINE OF DESCENT.

characteristics of the horse and rhinoceros with those
of the camel. How far the latter, as ruminants, are
directly connected with the Macrauchenidz, or whether
the form of their skull, approaching that of the horse,
points to actual homology, it is for the present impossible
to say.

The Anoplotheridz are likewise distinguished by a
sort of undifferentiated dentition, from which a number
of specific forms might deviate in different directions.
The Tragulide are descended from them in a direct
line; they form a small group not unlike the musk ani-
mals, and are confined to South Africa and Southern
Asia. As chewing the cud, they are more nearly allied
to the other typical ruminants with which we are ac-
quainted; but, on the other hand, they occupy an inter-
mediate position towards the other non-ruminants of the
division, of which the whole was united in the pre-historic
world through the Anoplotheride. The Suide, or pig-
like animals, were very profusely represented in the
Eocene and Miocene periods. From a side branch of
their predecessors, reaching up to the Anoplotheridz, are
descended the river-horses, or hippopotami. The func-
tion of ruminating is, as we know, correlated with a com-
plex structure of the stomach as well as a peculiar mech-
anism of the cesophagal groove. It is naturally im-
possible to determine in which fossil animals these
arrangements originated; yet it seems to have occurred
at a very early period. Perhaps the more highly in-
tegrated structure of some non-ruminating genera, such
as the hippopotamus and the peccary, may have been
transmitted from the age of the Anoplotheridez, and the
very conspicuous accordance of the ruminating Tragulide
PEDIGREE OF MAMMALS. 279,

with the Anoplotheridz stamps the latter with tolerable
certainty as ruminants.

Disregarding the camels, already mentioned as of
doubtful origin, the typical ruminants separate into the
deer-like and the horned. Through the hornless musk
animals, the deer are connected with the Tragulide and
the older genera. The giraffes form a side branch. But
although the Helladotherium, nearly allied to the giraffe
and at one time inhabiting the Athenian territory in herds,
and the colossal Sivatherium, found in the spurs of the
Himalayas, afford some clue to the position of the
giraffes, so entirely isolated in the present world, the
details of their derivation still remain very obscure.

From the antelopes to the closely allied—in fact,
scarcely separable—genera of goat and sheep, and
similarly to the oxen, the systematic as well as the pale-
ontological series, and likewise the ontogenetic phases,
present transitions undeniably evincing family relation-
ship. Besides the relations of the milk dentition of the
filial to the ancestral genera, which Rititimeyer has also
followed minutely, great interest attaches to the gradual
transformation of the skull, which reaches its extreme in
the oxen, and advances from the antelope and sheep,
through Ovibos, Bubalus (buffalo), Bison, to Bos (ox).
In the latter, the erect position of the frontal bone attains
its utmost grade, and this transformation of the skull of
the antelope is repeated in the calf.

The usual classification of the Sirenia, or sea-cows,
with the Cetacea, was decidedly a systematic misconcep-
tion, arising from one-sided and, moreover, merely su-
perficial consideration of the locomotive organs. All
other characteristic indications—above all, the structure
278 THE DOCTRINE OF DESCENT.

of the skull and the nature of the teeth—remove them
from the Cetacea as much as they approximate them
to the Ungulata. In the hippopotamus we have a mem-
ber of this order nearly converted into an aquatic animal.
We must think of the Sirenia as originally emanating
from some unknown genera, which probably branched
off at a very early period.

A very uncertain position is occupied by the Hyra-
coidz, now represented only by a few species of the
genus Hyrax. To say that their characteristics recall
at once the Ungulates, the Rodents, and the Insectivora,
affords no explanation. Considering the great impor-
tance of the molar teeth in deciding derivation, the
chief stress should perhaps be laid on their similar-
ity in the hyrax and the rhinoceros, and we hence
regard the hyrax as an offshoot of an old Ungulate
family.

With respect to the progenitors of the Proboscidz, we
refrain from any conjecture.

Later than the Graminivora, the Carnivora, and espe-
cially the beasts of prey, seem to have appeared on the
scene of arctic animal life. ‘Granting the possibility (and
it is scarcely possible to do otherwise) that placental for-
mations may have originated in various ways, the pos-
sibility likewise exists that the Carnivora, and indeed
other orders too, such as the Rodents especially, may
be direct descendants of carnivorous Marsupials. The
oldest beasts of prey known are feline, or resemble the
Viverride and hyenas. Then come the Canide, and
latest of all the Ursidz. In skull, dentition, and extremi-
ties, the seals and walruses (Pinnipedea) constitute a side
branch. Although there can be no idea of any special
PEDIGREE OF MAMMALS. 279

affinity between the otter and the seal, the comparison of
the two will aid us in imagining how from true beasts
of prey and terrestrial animals the strange figure of seals
and walruses must have proceeded.

If the conjecture already propounded should be con-
firmed, that the detachments and ejections of the placenta,
which constitute the phenomena of the decidua, assume
very heterogeneous forms in groups belonging to the
same family, and may be alike in others no more nearly
related, the Cetacea would he installed in our pedigree
in the vicinity of the beasts of prey. Between a lion and
a whale an angle is enclosed, containing a countless
multitude of intermediate forms. But we must always
bear in mind that our business is, not to bridge over
the chasms between the present peripheral ends of the
series of development representing the extreme forms,
but to discover the points of derivation and attach-
ment. Fossil whale-like animals are known in the Ter-
tiary period, such as the Zeuglodon and Squalodon.
The remains of the former colossal genus are kept in
good preservation at Berlin, where Johannes Miiller dis-
covered their relations to both seals and whales. The
dentition is seal-like; in the skeleton there is much
similarity with the whales; and although the Zeuglodons
must have been preceded by a great series of species,
and followed by another of considerable, if not equal,
length, before the present Cetacea proceeded from them,
a development of this sort seems, nevertheless, extremely
probable and natural. By their still perfect dentition
and the still proportionate dimensions of the skull, the
Delphinoidz are the oldest members of the true Cetacea.
They were joined by the sperm whales or cachelots

I,
280 THE DOCTRINE OF DESCENT.

(Physeteridz), and the last members are the right whales
(Balzenidz). This is evinced by the fact that the ‘whale-
bone or baleen plates are developed only after the ru-
dimentary teeth have made their appearance in the jaws
of the embryo, a heritage from the profusely and per-
sistently toothed ancestors.

In the Lemuridz, the system unites the heterogeneous
remains of a collection of animals which, by reason of
their prehensile hind feet with their opposable hallux,
were regarded as fellow-members of the order of “true
apes.” The connecting link is not their anatomical con-
stitution—they diverge widely in the form of the skull
and in dentition—but rather their geographical distribu-
tion, restricted to Madagascar and a few advanced posts
of Asia. Undue influence has also been allowed, cer-
tainly very unscientifically, to a certain peculiar outlandish
impression which they make upon the observer. The
constitution of their skull refers them to a very low
grade in the scale of the mammalia. If we view them
as a whole, they exhibit no general relations with any
particular order of mammals, but, according to the in-
dividual genera, point to those orders which, like them-
selves, possess discoidal placenta; the majority of rea-
sons favour the hypothesis that the Lemuridz now living
are the last and little modified offshoots of a division of
"mammals at one time far more richly developed, and
that Rodents, Insectivora, Cheiroptera, and Apes, are
twigs of this great branch.

The Rodents are particularly interesting, because, in
conjunction with stubborn persistency in the very
characteristically constituted dentition, accompanied by
several peculiarities of skull, they manifest the most ex-
PEDIGREE OF MAMMALS, 261

traordinary power of adaptation to arboreal and steppe-
life, to land and water. The Insectivora, although not
nearly so rich in species, offer a similar spectacle of
adaptations by which their genera have become almost
repetitions of the Rodents; and the Cheiroptera (bats),
in their most numerously represented division, may be
regarded as a side branch of the Insectivora, if they
have not proceeded directly from animals resembling the
Lemuridz.

In what geological period the monkeys were evolved
from lemur-like forms we do not know. The few fossil
monkeys with which we are acquainted belong to the
higher families of apes, and pre-suppose a long series
of ancestors. The same conjecture is forced upon us
by the geographical isolation of the American monkeys
from those of the Old World, which is also combined
with considerable anatomical differences, although it
could not occur to zoologists or comparative anatomists
to deny their close systematic affinity.

The relation of the lower to the higher apes requires
further discussion, which we shall combine with our dis-
quisition on the relation of man with the monkeys.
282 THE DOCTRINE OF DESCENT.

XII.

Man.

WHEN Goethe declares, “ We are eternally in contact
with problems. Man is an obscure being; he knows
little of the world, and of himself least of all,” 7?—he
almost repeats what J. J. Rousseau says in Emile,”
“We have no measure for this huge machine (the
world); we cannot calculate its relations; we know
neither its primary laws nor its final cause; we do not
know ourselves; we know neither our nature nor our
active principle.”

Such and such-like quotations are wont to be made
to us as justifying and confirming assertions of the nar-
rowness of our powers of understanding, and of the limits
of science. But in Anthropology we cannot possibly at-
tribute any greater authority to the worthy J. J. Rous-
seau than to a Father of the Church; and to the Goethe,
whose casual utterances are transmitted to posterity by
Eckermann, we oppose the other Goethe, who in the
fulness of youthful vigour, exclaims—

Joy, supreme Creation of Nature, feeling the power

. All sublimest thoughts, which lifted her as she made thee,
In thyself to re-echo——*

and who conceives the most beautiful organization, as he

* Freue dich, héchstes Geschépf der Natur, du fiihlest dich fahig
Ihr den héchsten Gedanken, zu dem sie schaffend sich aufschwang,
Nachzudenken——™
THE DOCTRINE OF DESCENT. 283

designates man, to be in perfect harmony with these
sublimest thoughts.

Our previous reflections and deductions would lack
their conclusion were man to be excluded,—could not
and must not all that is said of the genesis and connec-
tion of animal being, be directly applicable to the knowl-
edge of his nature also. The repugnance to the doctrine
of Descent, the doubt with regard to it, the indignation
lavished upon it, are all concentrated on its applicability
and application to man; and if the body be perforce
abandoned to us, the mental sphere of man is at least
to remain inscrutable, a molt tangere to the investigation
of nature. A few years ago, it was a consolation to the
opponents of the doctrine of Descent that Darwin had
not directly pronounced himself with respect to man.
Anger was vented on his adherents, who had outdar-
wined Darwin. To this was added the unfortunate mis-
apprehension that the champions of the doctrine of
Descent made the human race proceed from the ennoble-
ment of the orang, chimpanzee, or gorilla—in short, from
extant apes.

But from the first appearance of the Darwinian doc-
trine, every moderately logical thinker must have re-
garded man as similarly modifiable, and as the result of
the mutability of species; and Darwin has now told us,
in his work on the “ Descent of Man,” why he did not
enunciate this self-evident inference in his first book;
he did not wish thereby to strengthen and provoke preju-
dice against his view. Knowing human weakness, he.
withheld the conclusion. ‘It seemed to me sufficient,”
he says, “in the first edition of my ‘ Origin of Species,’
that by this work ‘light would be thrown on the origin
284 THE DOCTRINE OF DESCENT.

of man and his history,’ and this implies that man must
be included with other organic beings in any general con-
clusion respecting the manner of his appearance on this
earth.”

Nay, Darwin himself has now gone further, and, to
the terror of all who can scarce imagine man except as
created shaven and armed with a book on etiquette, he
has sketched a certainly not flattering, and perhaps in
many points not correct, portrait of our presumptive
ancestors in the phase of dawning humanity.

Before we seriously discuss this serious subject, we
will take leave to quote a more superficial verdict given
by a clever essayist.*4  “ Let us suppose, merely as a
joke, that Nature, which we see everywhere advancing
from the most simple to the compiex, from the lower to
the higher, had not suddenly waived this law in the
presence of man; that she had not suddenly given up
her evolution for his sake; that she had not suddenly
begun in him a new creation; but that here, as elsewhere,
she had proceeded quietly, gradually, naturally, and that
man was thus nothing more than the last link of the in-
terminable series of animals, nothing more than a ‘ de-
veloped ape.’ The first thought that would then ob-
trude itself upon us, would be that the facts were not
altered in the slightest degree; that man would remain
as he is, with the same shape, the same face, the same
gait, the same gestures, the same dispositions, powers,
feelings, thoughts, and with the same dominion over the
apes as heretofore. This is very simple, very self-evident,
but also very important. For it confers on him—on
man—the powerful sensation that, as he now is, he is
a being of a quite peculiar kind, very different from
SUPERFICIAL OBJECTIONS. 285

even the most kindred creature; and, moreover, that this
peculiar nature is his most peculiar property, whether
he received it as a ready-made gift, or worked it out
laboriously from a lower condition in tens of thousands
of years. But if his present constitution is not in the
slightest degree injured by his (assumed) animal origin,
neither can his aims and tasks, his endeavours and voca-
tions—in short, his whole future—be any other than,
from his entire nature, he must imagine and believe it to
be. Or must the cultivated portion of mankind be really
so profoundly dismayed by the idea of descending from
apes, that in despair at the impossibility of maintaining
and improving the civilization, which by no means fell
into their lap like ripe fruit, but which was painfuliy
acquired, they would abandon their business and pur-
suits, their forms of law and government, their arts and
sciences, and sink to the level of the Australian bush-
men—that they would let go that by which they had
raised themselves so far above the apes, and by which
they are constantly raising themselves still higher, merely
because it was once difficult to raise themselves above
these apes even by a hair’s breadth? But what man
destined by nature for a ruler, would have refused to
grasp the crown because his father was a hind? Or what
born Raphael would have forsworn palette and pencil,
because his parent had been a sign-painter? Mankind,
like each individual, will use and improve its powers be-
cause it has them, not because it has obtained them from
hither or thither.”

We give these transient fireworks their due, but we
require more profound arguments whence to derive the
final verdict. To the votaries of the doctrine of Descent,
'

286 THE DOCTRINE OF DESCENT.

its application to man is a simple deduction from a gen-
eral law, gained by the method of induction. As Goethe
postulated the inter-maxillary bone in man even before
he had seen or proved it, so must the doctrine of Descent
extend to man all its results and more or less plainly
demonstrated laws. The deduction is effected by the
accumulated observations of comparative anatomy, evo-
lutionary history, and paleontology, checking and con-
firming one another. Thus, for all who are not satis-
fied with belief in miracle and subjection to the hy-
pothesis of a revelation, nothing remains but the doctrine
of Descent. To apply it to man is not more hazardous,

‘but, on the contrary, as inherently necessary, as it is

for us zoologists to make use of it in judging some
polype hitherto unknown, a star-fish or a mouse. This
our adversaries deny. Man, they say, has qualities which
separate him absolutely from the animal, and, assum-
ing the doctrine of Descent generally, preclude its ap-
plicability in this one case. To this assertion, so fre-
quently to be heard, we will, in the first instance, oppose
a general remark as to the apprehension of human
nature..

It is commonly overlooked that, quite regardless of
the validity of the doctrine of Descent or even of its
existence, there is a notable inconsistency in the idea
of humanity. The philosophy of history has regarded
mutability, which is, in fact, capability of progress, as
the essence of human nature. But if any sort of in-
separable dependence of the mind upon the body be
admitted, as is the case with all but an extreme spirit-
ualistic party, the progress of mental power in mankind
was inconceivable without some parallel transformation
THE BODY OF MAN. 287

of the bodily substratum extending beyond the limits
of mere variability. Even on the assumption that the
mind forms its own organ, the brain, the specific idea
of man would necessarily have consisted in bodily im-
provement, as contrasted with the supposed rigidity of
the animal organism. For, in principle, it is the same
whether changes take place perceptibly in arms and legs,
or imperceptibly to the eye, in the molecules of the
brain. We are, therefore, only retrieving the shortcom-
ings of philosophy when we attribute to the bodily muta-
bility of man the extension which accrues to it from the
applicability of the doctrine of Descent to the particular
case.

The bodily accordance betwixt man and animal leaves
the doctrine of Descent so little to desire, that the ap-
prehension of Mephistopheles lest grovelling humanity
should finally be alarmed at his likeness to the Deity,
might far rather be applied to his likeness to the animal.
The human body, like the body of every animal, points
in its evolution to an elaboration from the undifferen-
tiated to the specialized form. The general distribution
of the body and the development of the several organs
is common to man and all mammals, and in the earlier
stages of the embryonic state to all vertebrate animals,
and indicates this general kinship. The existence there-
fore of a discoidal placenta (unless we prefer a special
reiterated new creation of this organ of development, in
which the Creator adhered to the pattern of the placenta
of the lemurs, rodents, insectivora, bats, and apes) reduces
us to the alternative that in the natural and to us un-
known development of man, chance, or some quite
different chain of causes, led in this case, as in the other,
288 THE DOCTRINE OF DESCENT.

to the discoidal placenta, or that the accordance is based
on consanguinity with the discoido-placental mammals.
We have already (p. 272) objected to the inference that
all mammalian orders are akin, should be drawn with
certainty from the superficial accordance of the placenta,
and we must therefore justify ourselves now, when we
lay a stress on the accordance of the placenta of man
and apes. The orders mentioned above all possess a
placenta of small extent and discoidal form. In the
shape of this disc, and in the number and distribution
of the blood-vessels in the umbilical cord by which the
foetal respiration and nutrition are carried on, sundry
varieties occur. Thus in the family of the Pithecoid
apes, the placenta falls into two discs, whereas the um-
bilical cord agrees with that of man; in the American
apes, on the contrary, the placenta is simple and the
blood-vessels are different. In the orang and gorilla we
know nothing of these organs, but the chimpanzee agrees
with man, in that it has a simple discoidal placenta with
two conducting (arteriz umbilicales) and one reconduct-
ing vessel (vena umbilicalis).

With a general similarity of the human placenta with
that of the discoido-placental mammals, man is especifi-
cally nearer to one at least of the so-called Anthropoid
apes, than this one is to the other apes. And thus the
constitution of the placenta is certainly of great impor-
tance in discriminating the systematic position of man.
Enormously improbable as is the chance contemplated
above, equally probable and solely credible is consan-
guinity; and with regard to general organization, in any
specific comparison of man with the mammalia, the apes
must occupy the foreground.
MAN AND APES. 289

This comparison has been admirably conducted by
Huxley and Broca.*? The latter has set himself the
task of investigating, solely as a descriptive anatomist
and zoologist, regardless of all dispute as to principle,
and undisturbed by the doctrine of Descent, whether the
anatomical constitution of man, as compared with that
of the ape, justifies, on general zoological principles, the
union of the two in a single order—Primates. Huxley
proves that the anthropomorphous apes (gibbon, chim-
panzee, orang, gorilla) differ from the lower apes much
more than from man; and that if we are obliged to as-
sume the reciprocal consanguinity of the apes, the com-
mon derivation of the anthropomorphous apes and man
is at least equally natural.

Between the peripheral members of the systematic
groups of monkeys—for instance, between the American
Sahuis and the Old-World Pavians and Anthropomorpha
—notable differences exist in the constitution of the limbs
and other parts of the skeleton, together with the soft
parts belonging to them, in the muscles especially, as
well as in dentition and the structure of the brain. It
is false to call apes quadrumana, for within the order of
the apes the contrast between hand and foot makes its
appearance in its essential anatomical attributes, and in
the anthropomorphous apes, in the gorilla especially, it
is almost as distinct as in man.

Luca, the anatomist renowned for his careful meas-
urements of the cranium, imagines that he has discerned
a highly important demarcation between man and the
ape. In the ape, the three bones forming the axis of
the skull, the basi-occipital bone, and the two sphenoid
bones, lie almost in a line, whereas in man there is a
290 THE DOCTRINE OF DESCENT.

double flexure of this axis; moreover, in the apes the
angles increase with age, which in man decrease, and
vice versé. Likewise in man the occipital foramen be-
comes more horizontal with age, more vertical in the ape.
But all this shows only, what the doctrine of Descent
asserts, that the two series, ape and man, diverge from
one another, and that the youthful individuals are more
alike than the older ones,—that the ape as he grows be-
comes more bestial; man, as the riddle of the sphinx
already intimated, more human. The flexure of the
basal bone and the horizontal position of the occipital
foramen occasions the upright gait, wherewith the dif-
ferentiation between hands and feet is completed. This
flexure of the cranial axis may therefore still be em-
phasized as a human character, in contradistinction to
the apes; the peculiar characteristic of an order can
scarcely be elicited from it; and especially as to the
question of Descent, this circumstance seems in no way
decisive.

Not only as regards hand and foot, but also in denti-
tion and brain, the anthropomorphous apes approach
man much more nearly than they do the inferior wide-
nosed monkeys of the New World. These, have six
molar teeth, and their brain displays the imperfections
of the brain of the lemurs and rodents. Like the mon-
keys of the Old World, on the contrary, the anthro-
pomorphous apes possess five molar teeth, and every
portion of the human brain, even to the hippocampus
minor, is likewise present.. The dispute as to this insig-
nificant portion of the brain, which R. Owen claimed
as an exclusively human characteristic, possesses a merely
historic interest, since, in conjunction with the posterior
MAN AND APES. 2g1

corner of the lateral ventricle, it has been exhibited by
a number of distinguished anatomists in the orang and
chimpanzee.

Thus, for those who will not relinquish their hope of
finding specific distinctions between the brain of man
and ape, there remain only the furrows and ridges on the
surface of the cerebrum, the so-called convolutions of the
brain. But here, again, it is in vain to look for funda-
mental differences, unless the chief stress is to be laid
upon the circumstance that in the human embryo the
folds commence in the frontal, in the apes in the supra-
orbital lobes. The constant convolutions common to
all human brains are seen in the orang and chimpanzee.
These convolutions are lost, or rather exist in less per-
fection, in the apes approaching the Anthropomorpha;
they are totally absent in the Ouistitis. But so great
is the resemblance of the brain of the two apes mentioned,
with that of man, that, as Broca says, “it requires the
eye of an experienced anatomist to discriminate, in
drawings reduced to the same dimensions, their brain
from the human brain, especially if the object of com-
parison selected, be the brain of negroes or Hottentots,
which are more simple than those of white men.” A
desperate attempt to rescue a specifically human cerebral
character was made by the lamented Gratiolet, the anat-
omist, of Paris. Man was to be distinguished by the
so-called transitional or bridging convolutions. These
transitional folds are convolutions, by which the pos-
terior lobes of the cerebrum are joined to the anterior
and lateral portions. But Broca has lucidly demon-
strated that it is the same with this as with other char-
acteristics, and that the transitional folds in the orang,
292 THE DOCTRINE OF DESCENT.

for instance, are far more like those of man than of
the chimpanzee, and that the differences which exist can
at the most have the value of specific or generic char-
acters, ,

The distance between the lower and higher apes is
far greater than between the latter and man; and if the
consanguinity of the entire apedom is decisive in favour
of Darwinistic views, there can be the less doubt of the
kindred connection of the Old-World apes to mankind.
But the form of the mature skull and of the dentition
(to lay a stress upon these organs), preclude the idea
that the direct ancestors of man are to be found among
the apes now living. The cheap jest, produced with so
much glee, of inquiring why we do not behold the in-
teresting spectacle of the transformation of a chimpanzee
into a man, or conversely, of a man by retrogression into
an orang, merely testifies the crudest ignorance of the
doctrine of Descent. Not one of these apes can revert
to the state of his primordial ancestors, because, except
by retrogression—by which a primordial condition is
by no means attained—he cannot divest himself of his
acquired characters fixed by heredity; nor can he ex-
ceed himself and become man; for man does not stand
in the direct line of development from the ape. The
development of the anthropoid apes has taken a lateral
course from the nearest human progenitors, and man
can as little be transformed into a gorilla as a squirrel
can be changed into a rat. Man’s kinship with the apes
is, therefore, not impugned by the bestial strength of
the teeth of a male orang or gorilla, or by the crests
and protuberances on the skulls of these animals. A
renowned zoologist, one of the few who adhere to the
MAN AND APES. 293

old belief, has taken the useless trouble of proving that
the skull of the orang could not possibly be transformed
into the human head. As if the doctrine of Descent had
ever asserted such nonsense! The bony skull of these
apes has reached an extreme, comparable to that of our
domestic cattle. But this extreme appears only grad-
ually in the course of growth, and the calf knows little
of it, but possesses, as we have already mentioned, the
cranial form of its antelope-like ancestors. In the present
antelopes, and likewise in goats and sheep, this form,
transitory in the calf, has remained stable. Now, as the
youthful skull of the anthropomorphous apes exhibits,
with undeniable distinctness, a descent from progenitors
with a well-formed and still plastic cranium, and a den-
tition approximating to that of man, the transformation
of these parts in conjunction with the brain, the latter
by reason of its persistently small volume, has, as it were,
struck out a disastrous path, while in the human branch,
selection has effected a higher conservation of these
cranial characters.

With this falls also the objection recently raised by the
venerable Karl Ernest v. Baer, that it is inconceivable
how, from.the monkey’s feet, arranged for climbing and
grasping, the human foot, adapted for flat treading and
walking, should be evolved in the struggle for existence.
The tendency to oppose the big toe to the others, that is,
to a prehensile foot, is known to be a human attribute,
and this tendency is certainly inherited. How far the
capacity for climbing may have been developed in the
primordial ancestors, is as much unknown as these pri-
mordial ancestors themselves. Thus the aptitude in
climbing shown by most of the present monkeys is only
294 THE DOCTRINE OF DESCENT.

remotely connected with the inaptitude of man, and as a
criterion of consanguinity, can hardly be taken into con-
sideration.

While requiring by logical deduction, a common
origin for man and the anthropomorphous apes, the doc-
trine of Descent, as it is almost superfluous to say, repu-
diates the senseless demand for intermediate forms be-
tween man and the gorilla. What future times may
perhaps discover, are intermediate forms which go back
to the common point of derivation of the present apes
and of man. And thus, notwithstanding the very close
relations already discussed, there remains the chasm
which is approximately expressed by the comparative
weights of the lowest human brain yet measured and the
brain of the gorilla. The brain of a bushwoman, nor-
mally efficient after the manner of her tribe, amounted
to 2 lbs. 4 ozs. (Cuvier’s brain weighed 4 Ibs. 4 ozs.), that
of a gorilla may be estimated, from the capacity of the
cranium, at about 1 lb. 6 ozs., which gives the approx-
imate ratio of 3:2. But exalted above the animal as
man may feel himself in his bodily nature, in this again
he forms no exception, as many animal forms occupy an
equally isolated position with reference to their unmis-
takably nearest kindred. '

Need we imagine a twofold creation of vertebrate
animals, because the lancelet is now separated from the
fishes by a whole scale of intermediate forms no longer
extant? The example of the horse is, among others,
highly instructive in this case. Let us bear in mind that,
in the nature of the limbs and teeth, this genus differs
far more from all other extant graminivora than man
differs from the ape. Had not the fossil ungulates been
DEFICIENCY OF INTERMEDIATE FORMS. 295

found which demonstrate the common origin of the horse
with the didactyles and the multidactyles, we should still
not deem the horse a special miraculous creation, but
incontrovertibly deduce his true kinship with the other
ungulata. This pure deduction is not requisite, as the
progenitors of the horse are present in conspicuous re-
mains; and, as we have already seen, elicited in R. Owen,
half a century ago, the conviction of a direct metamor-
phosis of the tridactyle genera into the unidactyle. Our
acquaintance with the tridactyle horses was a lucky
chance; they were indigenous in those parts of Europe
which have been most diligently laid bare and explored
in behalf of Palzeontology.

But that our museums are still destitute of the fossil
progenitors of man, is not more strange than the defi-
ciency, hitherto existing, of intermediate forms, which,
for example, would conclusively decide the position of
the Dinotherium in the system. We will also refer again
to the elephants, who, with their nearest ally, the mas-
todon, occupy towards the other Pachydermata a position
elucidated by no fossils, and far more isolated than that
of man to the apes. We hope herewith to have shown
that the argument that, by peculiarities not bridged over,
—by upright gait, comparative hairlessness, chin, prepon-
derance of brain, &c.,—man betrays a position absolutely
apart, cannot be admitted by comparative anatomy and
paleontology. The demand, therefore, that the ad-
herents of the doctrine of Descent should produce the
intermediate forms which at one time necessarily existed,
can be made only by dilettantes to whom the province
of life, as a whole, has remained a sealed book.

As we observed before, the bodily nature of man is

20
296 THE DOCTRINE OF DESCENT.

sometimes ceded to natural inquiry as a means of more
certainly rescuing the other side of the dualism. But
here, too, we will not be defrauded of our say and our
own opinion. The mental powers of man, in their origin,
growth, and effects, are likewise susceptible of investiga-
tion, and psychology only too long thought it possible
to elude physiology. Let us, therefore, proceed in good
heart to a short examination.

It is universally admitted that a certain relationship,
or analogy, exists in the psychical capacity of the higher
animals and man. Reason alone, it is said,—the essence
of psychical agencies by which man attains self-con-
sciousness, and rises to abstract conceptions, combines
ideas, especially religious ideas, and lives in art and sci-
ence,—this the animal does not possess. We reply that
animals certainly do not possess this degree of mental
development, but neither does man possess it in lower
phases of evolution.

The soul of the new-born infant is, in its manifesta-
tions, in no way different from that of the young ani-
mal; these manifestations are the functions of the in-
fantine nervous system; with this they grow and are de-
veloped together with speech. The grade to which this
development rises is generally dependent on the preced-
ing generations. The psychical capacities of each indi-
vidual bear the family type, and are determined by the
laws of heredity. For it is simply untrue that, inde-
pendently of colour and descent, each man, under con-
ditions otherwise alike, may attain a like pitch of mental
development. As a proof of this primary equality of
mankind, single instances of gifted negroes and Indians
are held up to us. But these have behind them un-
MENTAL PROGRESS. 297

numbered generations practised in. multifarious employ-
ments, skilled in human intercourse, even if it be one-
sided; and if these rare phenomena are thoroughly in-
vestigated, they still remain behind the average individ-
uals of advanced races. Now it is certain that in each
race, each individual passes through grades in the scale
of mental development, which, in perfect analogy
with the laws of anatomical development, are uni-
versally valid; whereas, as we have seen, the psycho-
logical peculiarities of the race become valid. But it
is in mankind as in the individual; in the lapse of time,
it has acquired those higher powers of mind which we
call Reason.

History shows, and no one denies, a mental advance,
but only in nations which have taken part in history,
and only so long as this part and the exercise of the
mental organs has been continued. But inferior human
races exist—we may also call them human species—
which are related to the others, as are lower animals to
higher. It might even be given as the characteristic of
the genus man, that its species occupy such extraor-
dinarily different grades of mental condition. We are
not misled by the contrary statements of missionaries
and other philanthropists; by the talk of human dignity
and divine resemblance; nor do we seek for consolation
in the development still to be expected in all nations
which have hitherto lagged behind. It is indeed self-
evident from the theory of descent and selection, that
many of the races now standing far behind in a mental
point of view will in future have made a great advance.
But for others, if we contemplate the ethnology and
anthropology of savages, not from the standpoint of
298 THE DOCTRINE OF DESCENT.

philanthropists and missionaries, but as cool and sober
naturalists, destruction in the struggle for existence as
a consequence of their retardation (itself regulated by
the universal conditions of development), is the natural
course of things.

If we examine the mental condition of mankind, and
compare it with the psychical capacities of animals, we
must not take the average Indian or European as our
standard, but the Australian and Papuan races, which
in body also have remained at a grade which the other
more favoured races outgrew in pre-historic times long
past. Many, it is true, overcome all difficulties, inas-
much as, assured of an equalizing human dignity as of
a dogma needing no further foundation, they are ready
with the assertion that it is impossible to doubt that
they have retrograded from a higher mental develop-
ment and sunk into barbarism. But if this possibility
might be admitted as regards some few races, such as
the Fuegians; in others, in the Australians for instance,
any real evidence of this previous more elevated condi-
tion is wanting.

The superior mental prerogatives which are supposed
to separate man from the animal, hinge more or less on
the following points.

Man alone, it is said, is capable of development or
progress. Specifically, human is all progress regulated
and effected by human speech, for many animals like-
wise possess the gift of communication. But if we are
not to imagine man as having advanced from all eternity,
the question is, how was this advance initiated, and the
whole concern is fundamentally reduced to the problem
of the origin of language. We will return to this subject.
FREE WILL. 299

Progress in general is not however to be denied to the
animal. Who can question that some canine races, of
which the descent from stupid jackals and wolves is as
good as certain, have raised themselves mentally far above
their ancestry? Who, that has read the comprehensive
investigations of H. Miller, the brother of our Fritz
Miller, can doubt that the honey-bee, as it gradually
attained its bodily advantages and peculiarities, devel-
oped likewise the higher mental powers, corresponding
with the more minute and complex organism of her
brain? Man—such is the thesis we propound, reserving
the question of language—differs from many animals only
in the degree and means of progress. It is therefore
unscientific to contrast humanity and animality in the
abstract.

Man alone, it is further maintained, has a free will.
In so far as the more highly developed man acts in
accordance with philosophical, moral and religious prin-
ciples, for which he is indebted to education and in-
struction—in so far as he is able to apprehend ideals,
and strive after them with his own mental and bodily
power, this command of will may be readily admitted,
although we know that this “ freedom” is likewise the
collective result of natural causes. But the more simple
and uniform the conditions of life, the more do the deal-
ings of men lose the semblance and character of free-
dom, and the more does the individual act after the will
of the tribe—I might say, of the herd—that is to say,
instinctively. In this case actions are not performed
even with the astounding premeditation with which some
few happily organized indlvidual animals of some few
species turn the circumstances to account with apparent-
_300 THE DOCTRINE OF DESCENT.

ly complete free will. The free will of the morally ele-
vated man, is no common property of all mankind.
Man alone, and all men, are supposed to have a con-
science. We consider, on the contrary, that conscience,
which is known to be utterly lost in many individuals
of even the most civilized nations, is, like moral will,
a result of education in some few races and tribes. Fear
of detection after a bad action, is not conscience; and
that well-trained dogs have sensations of conscientious
shame far superior to the animal terror of savage can-
nibals after they have wrought the murder of their fel- .
low-men, it is impossible to deny. Of this, evidence in
profusion is accumulated in the anthropological compila-
tions of Waitz.
, That a consciousness of the Divine existence is a
fundamental property of all men, we likewise hold in
question. It is, again, an established phrase that the most
barbarous nations are guided by emotions and cravings,
however obscure, towards the unknown God. This as-
sumption is as old as the well-known attempt to prove
the existence of God, “ De quo omnium natura consentit,
id verum esse necesse est” (That in which all intuitively
agree, must necessarily be true). How often has this
saying of Cicero been thoughtlessly repeated? This idea
of God is, however, as little intuitive as the discrimina-
tion of good and evil by the conscience. Others main-
tain the contrary. Thus Gerland says of the
Australians: 8° “The statement that Australian civiliza-
tion indicates a higher grade is nowhere more clearly
proved than here (in the province of religion), where
everything resounds like the expiring voices of a pre-
vious and richer age; but we in no way receive the im-
AUSTRALIAN IDEA OF GOD. 301

pression that we are dealing with stagnation or incom-
plete development. Thus the idea that the Australians
have no trace of religion or mythology is thoroughly
false. But this religion is certainly quite deteriorated,
and has degenerated into a wild, disjointed, and
often incredibly absurd demonology, into a superstitious
fear of apparitions.”

But when a few lines later in the work quoted, we are
informed that the natives to the west of the Liverpool
range, ascribe everything in nature which they cannot ex-
plain to the Devil-Devil, and that this is manifestly only
a name, derived from the English Devil, for a Deity of
whom they: have not preserved any distinct conception,
the shallowness of this evidence in favour of the hypothe-
sis of a previous standpoint, now sunk into oblivion, en-
ables us to infer the value of the other instances. We
have far more reason to believe this low state of mental
development in harmony with the bodily condition, when
we hear that the natives of the Gulf of St. Vincent and
the neighbourhood of Adelaide are extremely hairy, and
that even the brown-coloured down of the children is so
abundant and so long, that the skin of boys of five or six
years of age assumes a furry appearance. But, contrary
to all experience and history, we are required to believe **
that the inhabitants of the northern parts of Australia are
the most aboriginal, for ‘they are the most civilized, as
well as the best developed, in mind and body; they only
are fixed in one dwelling-place; and in any case the sup-
position is easier and more natural that the other natives
should have degenerated, with their eternal wanderings,
than that the former, fixed by the more convenient terri-
tory, should have raised themselves.”
302 THE DOCIRINE OF DESCENT.

This inverts all that has hitherto been called anthro-
pology. Moreover, there are even very advanced na-
tions without any consciousness of God. Schweinfurth
relates that the Niam-Niam, that highly interesting dwarf
people of Central Africa, have no word for God, and
therefore it must be supposed, not the idea; and Moritz
Wagner has given a whole selection of reports on the
absence of religious consciousness in inferior nations.
When, in spite of all these corroborations, it is always re-
torted afresh that even among the lowest savages some
sort of feeling of superior powers is manifested, the dis-
pute finally results in mere verbal criticism, which has
no farther interest for the doctrine of Descent.

And yet we cannot leave this subject without alluding
to a fact, universally known, but, strange to say, not as
yet employed in this connection, and which, as it would
seem, is by itself sufficient to invalidate the assertion that
the idea of God is immanent in human nature. We
mean the fact that many millions in the most cultivated
nations, and among them the most eminent and lucid
thinkers, have not the consciousness of a personal God;
those millions of whom the heroic David Strauss became
the spokesman when he adopted for his own the motto
of his favourite, Ulrich von Hutten: I have dared it—
Jacta est alea!

And now as to Language? All modern philologists
agree that languages are developed, and that most prob-
ably all linguistic families pass through three stages. In
the stage of the radical languages all words are roots,
and are merely placed side by side. In the second stage,
that of the agglutinated languages, one root defines the
other, and the defining root ultimately becomes merely
DEVELOPMENT OF LANGUAGE. 303

a determinative element. Finally, in the inflected lan-
guages, the determinating element, of which the deter-
minating significance has long vanished from the national
consciousness, unites into a whole with the formative ele-
ment. As we have said, this development, in which
retrogression takes an extensive share, is universally ad-
mitted. Opinions differ only as to the origin of the lin-
guistic material, which the acuteness of the philosophers
extracts in the guise of “roots.” A great authority,
Max Miiller,®* discerns in the existence of the roots
evidence of the absolute separation of man from the ani-
mal. While Locke says that man is distinguished from
the animal by the power of forming general ideas, the
philologist ought to say that human language is distin-
guished from the animal capacity of communication by
the power of forming roots. To trace up all words to
imitation and exclamatory sounds is inadmissible, as we
most frequently come upon roots of fixed form and gen-
eral meaning which are inexplicable in themselves. He
deems the existence of these ready-made roots, before
which linguistic science stands helpless, an insurmounta-
ble impediment to the apprehension of man as a link in the
general evolution of organisms.

This point excepted, this excellent scholar naturally
admits all those phenomena of heredity, acquisition, and
degeneration, which are manifested in the laws of lan-
guage, and find the?r most perfect analogies in our doc-
trine of Descent. If, for instance, we compare Zend
with Sanscrit, and hear several of its words explained,
we are at once reminded of the rudimentary organs and
their significance. A host of anomalies are, like the
isolated organisms of present times, primeval and pe-
304 THE DOCTRINE OF DESCENT.

culiarly normal remnants and witnesses of bygone lin-
guistic periods. In short, down to the minutest details,
linguistic research stumbles on accordance and analo-
gies with the doctrine of the derivation of organisms.
And, forsooth, we are to halt before the origin of lan-
guage as before a something incomprehensible and in-
scrutable!

This is not done, however, by the majority of com-
parative linguists in the present day. Though Max
Miller calls the roots “ phonetical fundamental types
produced by a power inherent in human nature,” though,
according to him, man in a more perfect state possessed
the power of giving to the reasonable conceptions of his
mind a better and more subtle expression, the talented
Lazarus Geiger ®’ terms the hypothesis of a now extinct
power of forming languages, and the other hypothesis
connected with it, of a primordial state of higher perfec-
tion, a recourse to the incomprehensible and a return to
a standpoint of mysticism. For that which is not un-
derstood is not necessarily incomprehensible. It is not
our business to side with Geiger, who attributes an essen-
tial share in the ejaculation of words to the visual per-
ceptions, or with Bleek, G. Curtius, Schleicher, Steinthal,
and many others, who assign to the imitation of sounds
the first place in the evocation of language. This much
is, however, certain, that although those who are not
critical, find Max Miiller’s standpoint highly convenient,
in science, it is unique. In this province, interwoven as
it is with the investigation of nature, the greater number
of authorities, on linguistic grounds, comparative and
philosophical, have been forced to the conclusion that,
from an irrational primordial state, man-like beings grad-
LANGUAGE AND MIND. 305

ually became human, while with language, the work of
many years, reason made its appearance.

As early as 1851, when the doctrine of Descent was
still unheard of, Steinthal 8° says: “As language arises,
mind originates.” Ten years after Darwin, Geiger
writes: “Language created reason; before language,
man was irrational.” To him, and to all who have aban-
doned the standpoint of mysticism, “man is a genus
springing from an animal condition by means of the
origin and unfolding of his idiosyncrasy.” And this con-
clusion is not, as orthodoxy and reaction are anxious to
impress upon the multitude, borrowed from Darwinism,
but deduced from linguistic inquiry in its own way, only
by a scientific method. It need only be indicated that,
as Geiger has historically proved in so many instances,
“slow development, the emergence of contrast from im-
perceptible deviations, is the cause that the same word ac-
quires various meanings;” that the creation of language
therefore rests upon this process, and nowhere makes its
appearance suddenly and abruptly; that the so-called laws
of sound are habits of sound; that the special meaning
which a sound has acquired in lapse of time is always the
result of mere chance, or, in other words, of development.

This deduction of linguistic inquiry most fully con-
firms the result of natural inquiry. And any one who
takes the trouble to follow the course of linguistic science
will be convinced that its champions, except, perhaps,
Bleek, Schleicher, and Friedrich Miller, are labouring
rather to discredit, than to acknowledge, the influence of
the doctrine of Descent. All the higher is our estimate
of it, and therewith the most powerful objection to the in-
clusion of man in the great law of derivation is set aside.
306 THE DOCTRINE OF DESCENT.

The rest is incidental and a matter of detail. The
question so often ventilated, and now thoroughly worn
out, whether mankind is descended from one or more
pairs, is solved by the inference that the stock in which
language first arose, separated itself gradually from its
animal progenitors, and that the selection which led to
language and reason necessarily took place among large
communities of individuals. The scriptural conception
of the unity of the human race would be more nearly
approached if all linguistic families pointed to a single
source. But if it could be shown that certain linguistic
families lead to utterly discordant roots, the investiga-
tion of nature might furnish the inevitable corollary that
language originated in various parts of the world,—
in other words, that a separation into species took place
before selection had reached the point of forming lan-
guage. The latter case is by far the most probable, and
is, in fact, received as the only one possible by most of
the linguists occupied with this question, and is most
especially defended by Friedrich Miiller.8® “At the
time,” he says, “ when there were races and no nations,
man was a speechless animal, as yet, entirely destitute
of the mental development which rests upon the agency
of language. Independently of the premisses unfolded
by natural history, this hypothesis is forced upon us by
the contemplation of the languages themselves. The
various families of languages, which linguistic science is
able to discriminate, not only presuppose, by their diver-
sity of form and material, several independent origins,
but, within one and the same race, they point to several
mutually independent points of origin.”

In order to afford the reader some notion of the con-
307

nection of the families of nations, we give the subjoined
pedigree, in which Friedrich Miiller closely adheres to

Haeckel’s sketch.

RACES OF MAN.

*SUOIJEU JO UISLIO pue asenSur] Jo uoreuLoy ay} Jo Suruulseg
aovl uveu
“BVPI. “SURIQNN « “eplaviq,

ae

We ‘20ur
-osuoy, ‘sAReAY = ueoNeWYy ‘only ‘suel[Rysny

"Sd0139N “$}0}
uvolyy ‘suendeg -ua}Jopy

“OHBISY ulajseq ‘o1UBIDO “sIye yy
‘aoey SALW | \ /

“Ayorea “yar “AJQUIVA -  *Kyayea
pesey-Ayng parrey-yus paitey-2929],J parrey-ynL
Sr Zs Qe

‘sotoads porrey-1y sens ‘saroads pairey-A[[OO MA,

 

UR, DATTIWG

“GNINNVYW dO SHOVY AHL AO AAUDIGAG SMaTInW GNV TawMoavH

It makes mention of species and races of mankind,

the species being regarded as no longer existing, while
308 THE DOCTRINE OF DESCENT,

the present forms of man are distinguished only as races.
On this subject, we shall not lavish many words, since,
examined in the light, it is an affair of words only. In
the order of Primates, man constitutes a single family,
and represents it by a single genus. Whether Negroes,
Caucasians, Papuans, American-Indians, &c., be called
species or races, matters little. The facility of intercross-
ing the different nations would favour their characteri-
zation as races; but as the crossing of species does not
differ in principle from the crossing of races, and as
to the bodily varieties displayed in colour, hair, skull,
limbs, and other characters are added the profound dif-
ferences of language, the division of the genus homo
into species, diverging into many races, seems after all
more natural. But ultimately, as in the question of spe-
cies in general, the individual feeling of each person
proves decisive. Whether it was a lucky hit to found
the division of mankind on the position of the hairs, in
tufts or equally distributed upon the scalp, and further-
more on the section of the hair, whether it be more
flat and oval or circular in form, and finally on the in-
clination to curl or to lie stiff and smooth, the future must
decide.

The twelve races cited in the table given above, may
be characterized by the aid of natural history; and as
within the limits of the best known races, languages
and families of languages may be found, which preclude
any common origin, it follows that the formation of
language began only after the still speechless primordial
man had diverged into races. In geological periods and
primordial history, all chronology is extremely decep-
tive: we may, nevertheless, acquiesce in an estimate made
ANTIQUITY OF MAN, 309

by Friedrich Miiller as to the development of the lan-
guages of the Mediterranean races. The linguistic fam-
ilies of the nations dwelling chiefly in the basin of the
Mediterranean are Basque, Caucasian, Hamito-Semitic
and Indo-Germanic languages. “The languages of
these four families,” says Friedrich Miller, “are, as is
generally accepted by the most competent linguists, not
mutually related. If we therefore see that the Mediter-
ranean race includes four families of people in no way
related to one another, the inference is obvious that, as
each language must be. traceable to a society, the single
race must have gradually fallen into four societies, of
which each independently created its own language. A
further inference is, that the race, as such, doe;
not acquire a language; for, were this the case, race
and language would now be co-extensive, which is not
the case.”

We must therefore assume that at the time when
the various nations of the Mediterranean race were one,—
the time when man belonged to no nation, but merely
to a race,—mankind was destitute of language. Miiller
considers 3000 years approximately sufficient for the
period elapsing between the divergence of the race into
still speechless societies, and the epoch at which they
formed nations, separated and characterized by lan-
guages; a period which might seem to many, estimated
as far too short. Ifthe ancient civilized people of Egypt
be now added on, and the period of its conjectured mi-
gration from Asia computed, “the year 6,500 before the
commencement of our chronology seems to be the
earliest epoch at which we may speak of a Hamito-
Semitic primzeval people in the north of Europe.” There-
310 THE DOCTRINE OF DESCENT.

fore a Mediterranean race already existed 12,000 years
ago. But what space of time was requisite to enable
primitive man to separate into races, is entirely beyond
computation, and the more so as not the slightest trace
of him has hitherto been found.

With the invariable testimony of Geology that the
periods of the terrestrial strata imperceptibly merged into
one another, and that, especially from the Tertiary,
through the Diluvial period, to the present age, conti-
nuity has been only locally interrupted, the question of
the ‘fossil man,” formerly looked upon as cardinal, has
assumed another aspect. In Europe, man lived with
the mammoth and the rhinoceros with a bony nasal par-
tition (Elephas primogenius, Rhinocerus tichorhinus).
It has been asserted that European man existed as early
as the upper Tertiary age, but the evidence is disputa-
ble. Such remains as we have of this oldest man known
to us, display a high grade of development, and cer-
tainly belong to the period at which man had already
found in language the implement wherewith gradually
to free himself from the dross of his lowly origin.
Whether the primitive man be found or not, his origin
is certain.
REFERENCES AND QUOTATIONS.

‘ Luthardt, Apologetische Vortrage. 7 Vortrag. P. 129.

? Philosophia quaerit, theologia invenit, religio possidet veri-
tatem.

° Tageblatt der Naturforscher-Versammlung in Leipzig, 1872.
P. 12. The discourse was also printed separately.

“A. Fick, Physiologie, 1860.

® Any one who wishes to be more deeply instructed in the
problem of sensation, as an universal primary characteristic of the

‘constituent elements of matter, may be referred to the very lucid

and interesting work, “Das Unbewuste vom Standpunkt der
Physiologie und Descendenztheorie” (Berlin, 1872). Published
anonymously.

*L. Geiger, Ueber den Ursprung der Sprache. (Stuttgart,
1869.) P. 207. .

7 Rollet, Ueber Elementartheile und Gewebe und deren Unter-
scheidung. Rollet, Untersuchungen, etc. 1871.

® Karl Ernst v. Bar, Ueber Entwickelungsgeschichte der
Thiere, Beobachtung und Reflexion, 1828.

° Ib. I. 223.

Ib. I. 230, &c.

4 Credner, Elemente der Geologie, 1872. P. 253.

1 Agassiz, Essay on Classification, 1858. ‘It exhibits every-
where the working of the same creative Mind, through all times,
and upon the whole surface of the globe.”

18 Riitimeyer, Beitrage zur Kenntniss der fossilen Pferde.
Verhandlung der naturforschenden Gesellschaft in Basel, 1863.

III. 642.
21 311
312 THE DOCTRINE OF DESCENT.

“The passages are from an occasional address—Oratio de
ellure halvitabili—contained in the Amoenitates academice. “ Initio
rerum ex omni specie viventium unicum sexus par fuisse creatum,
suadet ratio.”

* Ib. Non multum a veritate me aberratum confido, si dixerim,
omnen continentem terram fuisse in infantia mundi aquis sub-
mersam et vasto oceano obtectam, preter unicam in immenso
hoc pelago insulam, in qua commode habitaverint animalia omnia
et vegetabilia late germinaverint.”

46 Tot numeramus species, quot ab initio creavit infinitum ens.”’

™ Geoffroy St. Hilaire wrote to Cuvier: ‘‘ Venez jouer parmi
nous le réle de Linné, d’un autre légisiateur de l'histoire naturelle.”

*® Ossements fossiles.

#” L. Agassiz, An Essay on Classification, 1859. P. 253 :—

“As representatives of Speczes, individual animals bear the
closest relations to one another; they exhibit definite relations also
to the surrounding element, and their existence is limited within a
definite period.

“As representatives of Genera these same individuals have a
definite and specific ultimate structure, identical with that of the
representatives of other species,”’ etc. See also P. 261 :—

“ Branches or types are characterized by the plan of their struc-
ture;

“‘ Classes, by the manner in which that plan is executed, as far
as ways and means are concerned ;

“ Orders, by the degrees of complication of that structure ;

“ Families, by their form, as far as determined by structure ;

“ Genera, by the details of the execution in special parts; and,

“« Spectes, by the relations of individuals to one another,-and to
the world in which they live, as well as by the proportions-of their
parts, their ornamentation,” etc.

2° Haeckel, Generelle Morphologie der Organismen (Berlin, 1866).
IT. 323, &c.

4 L’espéce est—‘‘la réunion des individus descendant l'un de
l'autre et des parents communs, et de ceux qui leur ressemblent
autant qu’ils se ressemblent entr’eux.” Cuvier, Le Régne Ani-
mal.
REFERENCES AND QUOTATIONS. 313

* OQ. Schmidt, Die Spongien der Kiiste von Algier, 1868, and
Versuch einer Spongienfauna des atlantischen Gebietes, 1870.

** Haeckel, Die Kalkschwamme. Eine Monographie in Zwei
Banden, Text und einem Atlas mit 60 Tafeln Abbildungen (Berlin,
1872).

*4 Hilgendorf, Ueber Planorbis multiformis in Steinheimer Siiss-
wasserkalk. Monatsbericht des Berliner Akademie aus dem Jahre
1866. P. 474, &c.

*® Waagen, Die Formenreihe des Ammonites subradiatus.
Beneke’s Beitrige, 1869. Vol. 2.

Zittel, Die Fauna der dltern Cephalopoden fiihrenden Tithonbil-
dungen. Palaontologische Mittheilungen,.1870.

Neumayr, Jurastudien, Jahrbuch det geologischen Reichsanstalt,
1871.

L. Wiirtenberger, Neuer Beitrag zum geologischen Beweise der
Darwin’ schen Theorie, 1873.

6 Darwin, The Variation of Plants and Animals under Domesti-
cation, 1868.

“7 L. Oken, Die Zeugung, 1805. Lehrbuch der Naturphiloso-
phie, 1809-11, Pt. 3.

°8 T have borrowed the following account from my essay: ‘“‘ Wae
Goethe ein Darwinianer?”” (Was Goethe a Darwinist?) Gratz,
Leuschner and Lubinsky, 1871.

Also another small work of mine: “ Goethe’s Verhaltniss zu den
organischen Naturwissenschaften”’ (Berlin, 1852). To the pas-
sages given in the text, which might make Goethe appear as a
Darwinist, I may add the following from Eckermann’s ‘‘ Gesprache
mit Goethe” (3 Ed. p. 191). ‘Thus man has in his skull ‘two
empty cavities. The question why? would not go far, whereas
the question how? teaches me that these cavities are remains
of the animal skull, which in those inferior organisms exist to
a greater degree, and are not entirely lost even in man, notwith-
standing his higher elevation.”

29 A somewhat depreciative opinion of Goethe’s importance in
this sphere is pronounced by V. Carus in his “Geschichte der
Zoologie”” (Miinchen, 1872). The reader, may compare: ‘“ How
little, notwithstanding his repeated study of anatomy, he had
314 THE DOCTRINE OF DESCENT.

gained a true insight into the structure of animals, as determined
by law, is testified by his Introduction to Comparative Anatomy.
He finds no other means of harmonizing the dry details of descrip-
tive anatomy, and the morphology which vaguely hovered before
him, but by indicating the idea of a primitive type for animals,
which he is, however, unable to define or to render in any way
palpable by more general indications. His whole idiosyncrasy
made such a type a necessity to him, not scientifically, but zstheti-
cally,” etc. P. 590.

5° R. Owen has declared his attitude towards the doctrine of
descent in the concluding chapter of his ‘‘ Manual of the Com-
parative Anatomy of the Vertebrata.’ It is published sepa-
rately under the title of ‘Derivative Hypothesis of Life and
Species,” 1868.

SE TDs sca “‘such cause being the servant of predetermining
intelligent will,”’

32 « No one can enter the saddling-ground at Epsom before the
start for the Derby, without feeling that the glossy-coated, proudly-
stepping creatures led out before him are the most perfect and
beautiful of quadrupeds. As such, I believe the horse to have
been predestined and prepared for man.”” Ib. P. 11,

83 «T deem an innate tendency to deviate from parental type,
operating through periods of adequate duration, to be the most
probable nature or way of operation of the secondary law whereby
species have been derived one from the other.” Ib. P. 22.

34 Lamarck, Philosophie Zoologique (Paris, 1809). In the text
allusion is made to the following passages:

« Ainsil’on peut assurer que, parmi ses productions, la nature n’a
réellement formé ni classes, ni ordres, ni familles, ni espéces con-
stantes, mais seulement des individus qui se succédent les uns aux
autres, et qui ressemblent 4 ceux qui les ont produits. Or ces
individus appartiennent a des races infiniment diversifiées, qui
se nuancent sous toutes les formes et dans tous les degrés
d’organisation, et qui chacune se conservent sans mutation tant
qu’aucune cause de changement n’agit sur elles.” I. 22.

“La supposition presque généralment admise, que les corps
vivans constituent des espéces constamment distinctes par des
REFERENCES AND QUOTATIONS. 315

caractéres invariables, et que l’existence de ces espéces est aussi
ancienne que celle de la nature méme, fut établie dans un temps
ot l’on n’avait pas suffisament observé, et ot les sciences naturelles
étaient 4 peu prés nulles. Elle est tous les jours démentie aux
yeux de ceux qui ont beaucoup vu et qui ont longtemps suivi la
nature.” I. 54.

“Les espéces n’ont réellement qu’une constance relative a la
durée des circonstances dans lesquelles se sont trouvés les indi-
vidus qui les représentent.” I. 55.

“«—les considérations, et nous font voir—

“rt, Que tous les corps organisés de notre globe sont de vérita-
bles productions de la nature, qu’elle a successivement executées
a la suite de beaucoup de temps.

“2, Que dans sa marche la nature a commencé et recommence
encore tous les jours, par former les corps organisés les plus
simples, et qu’elle ne forme directement que ceux-la, c’est 4 dire
que ses premiéres ébauches de l’organisation, qu'on a désignées
par l'expression de générations spontanées.

«3, Que les premiéres ébauches de l’animal et du vegétal étant
formées dans les lieux et les circonstances convenables, les facultés
d'une vie commengante et d'un mouvement organique établi ont
nécessairement developpé peu a peu les organes, et qu’avec le
temps elles les ont diversifiés ainsi qui les parties.

“4. Que la faculté d’accroissement dans chaque portion du corps
organisé était inhérente aux premiers effets de la vie; elle a donné
lieu aux différens modes de la multiplication et de régénérations
des individus; et que par la, les progrés acquis dans la composi-
tion de Vorganisation et dans la forme et la diversité des parties
ont été conservés.

“5, Qu’a l’aide d’un temps suffisant, des circonstances qui ont
été nécessairement favorables, des changemens que tous les points
de la surface du globe ont successivement subis dans leur état, en
un mot, du pouvoir qu'ont les nouvelles situations et les nouvelles
habitudes pour modifier les organes des corps doués de la vie,
tous ceux qui existent maintenant ont été insensiblement formés
tels que nous les voyons.

“6, Enfin, que d’aprés un ordre semblable de choses, les corps
316 THE DOCTRINE OF DESCENT.

vivants ayant éprouvé chacun des changemens plus ou moins
grands dans l'état de leur organisation et de leurs parties, ce qu’on
nomme espéce parmi eux a été insensiblement et successivement
ainsi formé, n’a qu’une constance relative dans son état, et ne peut
ainsi étre aussi ancien que la nature.” I. 65, &c.

“La progession dans la composition de l’organisation subit. ¢a
et la, dans la série générale des animaux, des anomalies opérées par
l'influence des circonstances d’habitation et par celle des habitudes
contractées.”” I. 135.

“Dans tout animal qui n’a point dépassé la terme de ses
developpemens, l’emploi plus fréquent et routiné d’un organe
quelconque fortifie peu 4 peu cet organe, le developpe, l’agrandit,
et lui donne une puissance proportionnée a la durée de cet emploi;
tandis quel e défaut constant d’usage de tel organe l'affaiblit
insensiblement, le détériore, diminue progressivement ses facultés,
et finit par le faire disparaitre.

“ Tout ce que la nature a fait acquerir ou perdre aux individus
par l’influence des circonstances ot leur race se trouve depuis
longtemps exposée, et par conséquent, par l'influence de l'emploi
prédominant de tel organe ou par celle d’un défaut constant
d'usage de telle partie, elle le conserve par génération aux nou-
veaux individus qui en proviennent.” I. 235.

“La volonté dépendant toujours d’un jugement quelconque
n'est jamais véritablement libre ; car le jugement qui y donne
heu est, comme le quotient d’une opération arithmétique, un ré-
sultat nécessaire de l'ensemble des éléments qui l’ont formé.”
I. 342.

“Les animaux contractent, pour satisfaire 4 ces besoins, diverses
sortes d’habitudes, qui se transforment en eux en autant de
penchans, auxquels ils ne peuvent resister et qu'ils ne peuvent
changer eux mémes. De 1a l’origine de leurs actions habituelles
et de leurs inclinations particuliéres, auxquelles on a donné le nom
d'instinct. Ce penchant des animaux a la conservation des habi-
tudes et au renouvellement des actions qui en proviennent, étant
une fois acquis, se propage ensuite dans les individus, par la voie
de la reproduction ou de la génération, qui conserve ]’organisation
et la disposition des parties dans leur état obtenu, en sorte que ce
REFERENCES AND QUOTATIONS. 317

méme penchant existe déja dans les nouveaux individus, avant
méme quills l’aient exercé.”” I. 325.

8° The acute author of the book, ‘‘Das Unbewusste’’ defines
instinct in essentially the same manner as Lamarck. “In this
sense it may be said that every instinct is in the last instance by
its origin an acquired habit, and the proverb .that ‘habit is
second nature’ thus receives the unexpected supplement that habit
is also the beginning and origin of the first nature, z. ¢., of instinct.
For it is always habit, ¢.¢., the frequent repetition of the same
function, which so firmly impresses the mode of action, however
acquired, upon the central organs of the nervous system that the
predisposition thus originated becomes transmissible,”’ p. 182.

%° ‘The highly important doctrine which Lyell has substantiated
with his rich experience is also distinctly and concisely enunciated
by Lamarck in the Philosophie Zoologique :—

“Sil’on considére, d’une part, que dans tout ce que la nature opére
elle ne fait rien brusquement, et que partout elle agit avec lenteur
et par dégrés successifs, et de l'autre part que les causes particu-
liéres ou locales des désordres, des bouleversemens, des déplace-
mens, etc., peuvent rendre raison de tout ce que l’on observe a la
surface de notre globe, et sont néanmoins assujetties a. ses lois et
a sa marche générale, on reconnaftra qu’il n’est nullement nécessaire
de supposer qu’une catastrophe universelle est venue culbuter et
détruire une grande partie des opérations mémes de la nature.” I. 80.

5" Principles of Geology.

88 In 1870, as well as in 1872, the majority in the French
Academy bore this testimony to Darwin. The reiterated proposal
of electing him a member was certainly not rejected until such
men as Milne-Edwards and Quatrefages .had made the stand-
point clear to the scientific judges.

® Origin of Species. Fifth Ed. 1872.

The other works cited are, “The Variation of Animals and
Plants under Domestication,” 1868; ‘“‘ The Descent of Man and
Sexual Selection,”’ 2nd ed., 1871; ‘‘ Expression of the Emotions in
Man and Animals,” 1872.

*° Malthus (1798) investigated the saaduions of the increase and
decrease of human population. He finds that the rise in popula-
318 THE DOCTRINE OF DESCENT.

tion is necessarily limited by the means of subsistence, and that
the growth increases in proportion to the means of subsistence,
setting aside some special impediments easily discovered. These
. impediments, which always keep the population below the amount
warranted by the means of subsistence, are moral restraint, crime,
and misfortune. Malthus depicts the struggle for existence without
pronouncing the word; he demonstrates that the dreams of a
future blissful equality of all mankind on the, earth transformed
into a vast garden, are based upon delusions. Each individual
must much rather labour indefatigably to ameliorate his position.
By the experience of breeders and gardeners he knows that
animals and plants may be improved and ennobled. No organic
ennoblement of the human race as a whole is perceptible, nor can
the human race be ennobled save by condemning the less perfect
individuals to celibacy.

These, and similar thoughts in the work of Malthus, first sug~
gested Darwin’s theory, as he has informed us.

“ Variation of Animals and Plants. I. 100.

“ Two treatises by A. Kerner are also very instructive with
regard to the question of species: ‘‘Gute and Schlechte Arten.”
(Innsbruck, 1866.) And “ Die Abhangigkeit der Pflanzenwelt von
Klima und Boden. Ein Beitrag zur Lehre von der Enstehung und
Verbreitung der Arten, gestiitzt auf die Verwandtschaftsverhaltnisse,
geographische Verbreitung und Geschichte der Cytisusarten aus
dem Stamme Tubocytisus D.C.’ 1869. Kerner’s latest work, ‘Die
Schutzmittel des Pollens” (Innsbruck, 1873), is likewise an ad-
mirable investigation of the variability, adaptation, and formation
of species. .

“8 Origin of Species. 13th ed. p. 84.

“4 Origin of Species. 13th ed. p. 96.

“* Origin of Species.

“P.7, The following pages contain an epitome of the objec-
tions offered to the inadequacy of the theory of selection.

“" Moritz Wagner, Die Darwin’sche Theorie und das Migrations-
gesetz der Organismen, 1848.

“ Nageli, Enstehung und Begriff der naturhistorischen Art.
(Sitzungsberichte der bairischen Akademie der Wissenschaften),
REFERENCES AND QUOTATIONS. 319

1865. Nageli’s later investigations (Sitzungsberichte der mathe-
matisch-physikalischen Klasse der Miinchner Akademie, 1872,
Pp- 305) contirm the doctrine of descent. He shows that the grega~
riousness of merely allied species and their varieties proves more
favourable to the formation of species than isolation. ‘The asso-
ciated forms—of certain Alpine plants—have, as it were, recipro-
cally modified one another; they exhibit, to express myself thus,
« specific social type, which zs different in each assemblage,
and therefore in every neighbourhood. This fact incontro-
vertibly shows that the forms have altered since they were asso-
ctated,

“The specific social type consists in their showing a notable
accordance in certain characteristics, while in others they repre-
sent extremes, and in these sometimes exceed all their congeners
in other districts.

“From these facts it follows undoubtedly that the movement in
the cenobitic forms (z. e. living together) is divergent. For extreme
characteristics are developed in them, whereas the eremitical
forms exhibit a medium in their characteristics.

“Nageli proves that since the glacial period an alteration
has taken place in Alpine plants, and the manner in which it
occurred.”

5 J. Broca, L’Ordre des Primates. Paralléle anatomique de
l'homme and des singes, 1870.

*\ Descent of Man, p. 367.

52 At the time at which we write, we have before us, unfortunately,
only the incomplete reports of the daily papers, and the syllabus
of Professor Max Miiller’s “Three Lectures on Mr. Darwin's
Philosophy of Language.” ‘

53 Z6llner, ‘‘ Ueber die Natur der Kometen ” (1 ed. p. 305).

5 For the further instruction of the reader, we will allow another
Philosopher and Naturalist to speak respecting the primordial com-
mencement of life, to’ our apprehension so simply accountable.
The hypothesis of origin is under discussion. In the critical
examination of the ‘“ Philosophie des Unbewussten” (7) it runs
thus, p. 22. The “ Philosophie des Unbewussten”’ says, p. 558:
“It is probable that before the origin of the first organisms,
320 THE DOCTRINE OF DESCENT.

organic combinations existed which (p. 556) were under the influ-
ence of a damp atmosphere, abounding in carbonic acid, and of a
higher temperature, light, and stronger electric influences. If these
presuppositions are adopted, and the consideration added that if
conditions thus favourable to primordial generation once existed.
which they must have done—they probably endured during con-
siderable geological periods—the inference is in truth inevitable
that in lapse of time and with change of circumstances, these
organic substances aggregated into innumerable combinations.
Among these innumerable modes of arrangement, groupings and
combinations, by far the greater portion must remain at the
grade of inorganic form, because it has not attained the needful
chemical composition and physical properties ; a very much small-
er portion of the results produced by these combinations of or-
- ganic materials might perhaps transitorily approach the organic
form or even actually assume it, yet without possessing the con-
stitution necessary to maintain it permanently; a third and yet
smaller portion might perhaps maintain this form for itself in
the exchange of mater:al, about as long as the approximate du-
ration of life of one of the most primitive of the present Pro-
tists, yet lacked those properties which preserve the species by
division and reproduction after the natural extinction of the
individual; a fourth portion might possess the properties requi-
site for self-preservation as well as.for the preservation of the
genus, yet lacked that peculiar tendency to vary (Philosophie des
Unbewussten, p. 591), or at least that tendency to vary in the
particular direction which was alone capable of leading to de-
velopment into higher forms; and finally a fifth portion possessed
this property in addition to the others. It is the progeny of the
fourth and fifth classes of our division which still populates the
ocean and the earth.* From which species of Monera_ pro-
ceeded the advanced development of the Infusoria ; whether
from one still living or from an extinct species we do not know

*It is a simpler and more probable explanation that these low
organisms continue to exist because there is room for them. They
remain in spite of differentiation and in consequence of differentia-
tion.
REFERENCES AND QUOTATIONS. 321

as yet; but this much we may accept as certain, that the ma-
jority of the Protists that we still know, belong to that fourth
class which is incapable of development. The persistence of the
ephemeral creations of our second and third classes would natu-
rally be secured only so long as circumstances continued favour-
able to their renewed primordial generation, but from the telev-
logical standpoint the first class must be described as that of the
completely abortive attempts at creation.”

These, and similar more or less interesting fancies to which we
attribute no great importance, are all derived from Haeckel’s
hypothesis of Autogony (“Generelle Morphologie der Organis-
men,” 179 seq.), which he set up after his beautiful discoveries on
the simplest organisms now existing—the Monera and the Protists.
From this work we select the following passage :—‘‘ Doubtless we
must imagine the act of autogony, the first spontaneous origin of
the simplest organisms, to be quite similar to the act of crystal-
lization. In a fluid, holding in solution the chemical elements
composing the organism, in consequence of certain movements of
the various elements among themselves, certain points of attrac-
tion are formed, at which the atoms of the organogenetic ele-
ments (carbon, oxygen, hydrogen, nitrogen) enter into such close
contact with one another that they unite in the formation of a
complex ternary or quaternary molecule. This primary group
of atoms—perhaps a molecule of albumen — now acts like the
analogous crystalline molecule, attracting the homogeneous atoms
dissolved in the mother wather; and they now likewise coalesce
in the formation of similar molecules, The albuminous granule
thus grows and transforms itself into a homogeneous organic in-
dividual, a structureless moner or mass of plasma, like a Pro-
tameba, &c. Owing to the easy divisibility of its substance, this
moner constantly tends towards the dissolution of its recenily
consolidated individuality, but when the constantly prepondera-
ting absorption of new substance outweighs the tendency to dis-
integration, it is able to preserve life by the exchange of material.
The homogeneous organic individual, or moner, grows by means
of imbibition (nutrition) only until the attractive. power of the
centre no longer suffices to hold the whole mass together. In
322 THE DOCTRINE OF DESCENT..

consequence of the preponderating divergent movements of the
molecules in different directions, two or more centres of attrac-
tion are now formed in the homogeneous plasma, which hence-
forth act attractively on the individual substance of the simple
mould, and thereby induce its fission, or partition, into two or
more portions (reproduction). Each part forthwith rounds itself
again into an albuminous individual, or mass of plasma, and the
eternal process begins again, of attraction and disruption of the
molecules, producing the phenomena of exchange of substance, or
nutrition, and reproduction.”

Relying on the known peculiarities of the combinations of
carbon, Haeckel has .attributed to this substance the most im-
portant part in his representation of the first development of life
and the physiological phenomena of the lowest organisms. This
is the “carbon theory ” so strongly deprecated by his antagonists.
Minds would be less heated on the subject were it remembered
that a refutation of this “adventurous attempt,” as Haeckel terms
it, to assist the idea of genesis, would not change a hair in the
compulsory logical necessity of acknowledging the evocation of
life by natural means. The arguments against the carbon theory
have been developed, among others, by Preyer, ‘ Ueber die Er-
forschung des Lebens (Jena, 1873). It is shown that carbon,
in its present terrestrial conditions, points almost exclusively to
organic origin, and, as yet, no source of carbon has been de-
monstrated adequate for the first formation of living bodies on the
earth. :

°° A. R, Wallace, The Malay Archipelago (3rd ed.: London,
1872), and Contributions to the Theory of Natural Selection (2nd
ed.: 1871).

56 «The hypothesis of Pangenesis, as applied to the several
great classes of facts just discussed, no doubt is extremely com-
plex, but so assuredly are the facts. The assumptions, how-
ever, on which the hypothesis rests cannot be considered as
complex in any extreme degree; namely, that all organic units,
besides having the power, as is generally admitted, of growing
by self-division, throw off free and minute atoms of their con-
tents, that is, gemmules. These multiply, and aggregate them-
REFERENCES AND QUOTATIONS. 323

selves into buds and the sexual elements; their development de-
pends on their union with other nascent cells, or units, and they
are capable of transmission in a dormant state to successive gen-
erations.

“In a highly organised and complex animal, the gemmules
thrown off from each different cell, or unit, throughout the body
must be inconceivably numerous and minute. Each unit of each
part, as it changes during development —and we know that
some insects undergo, at least, twenty metamorphoses— must
throw off its gemmules. All organic beings, moreover, include
many dormant gemmules derived from their grand-parents and
more remote progenitors. These almost infinitely numerous and
minute gemmules must be included in each bud, ovule, spermao-
zoon, and pollen grain. Such an admission will be declared im-
possible, but, as previously remarked, number and size are only
relative difficulties, and the eggs or seeds produced by certain
animals or plants are so numerous that they cannot be grasped
by the intellect.” Darwin, Variations of Animals and Plants,
Il. 526.

37 A. Rollet, Ueber die Erscheinungsformen des Lebens und den
beharrlichen Zeugen ihres Zusammenhanges. Almanach der kais.
Akademie der Wissenschaften (Wien, 1872).

® Darwin, Variations of Animals and Plants, I. 200.

8° VY. Graber, Ueber den Tonapparat der Locustiden, ein Beitrag
zum Darwinismus. Zeitschrift fiir wissenschaftliche Zoologie.
Vol. 22. !

® Hermann v. Nathusius, Vorstudien fiir Geschichte und Zucht
der Hausthiere zunachst am Schweineschadel, 1864.

% Ib., p. 108.

82 Descent of Man, I. 412.

* Origin of Species. 13th ed., p. 171.

*4 |. amarck also constructed a pedigree at the end of his ‘ Philo-
sophie Zoologique,” in which he disposes of the greater number
of classes, while he attributes to the remainder another point of
derivation. He thus assumes in the animal kingdom two primordial
forms derived from primordial generation. His scheme is as
follows :—
324 THE DOCTRINE OF DESCENT.

TABLEAU
Servant & montrer l'origine des differents animaux.
Vers, Infusoires,
ee eash cn) Polypes.
Heleiae tas Mh eee, Radiares,
_yhguueeer SE Insectes.
res Arachnides,
Annelides. Crustacées.
Cirripedes.
Mollusques.
eh Poissons.
Reptiles.
‘

Oiseaux. =
5 Mammales amphibiens.

Monotrémes.

 

M. cetacées.

“ML ongulés. -

A comparison of this pedigree with the one which we now set up
is extremely interesting, and shows the progress of our knowledge.

* Zum Streit iiber den Darwinismus, ‘“‘ Augsburger Allgemeine
Zeitung,” 1873, No. 130.

®° A short preliminary communication in the “ Revue Scienti-
fique”’ (Paris, 1873). No. 37.

*" Braun, Ueber die Bedeutung der Entwickelung in der
Naturgeschichte (Berlin, 1872).

“The vegetal kingdom shows us—

“T. Plants, which in their vegetative development of the germ,

Mammales onguiculés.
REFERENCES AND QUOTATIONS. 325

exhibit a sexual generation, mostly in a thallus-like form. (Thallo-
gens, Bryophytes, the Thallophytes of the authors, and Charas and
Mosses.)

“II. Plants in which the first generation is transitory, and only
the second develops into the vegetative, leaf-forming stem, with-
out, however, advancing to the stage of phenogams. (Acrogens
Cormophytes, the ferns, &c.)

“III, Plants in which metamorphosis advances as far‘as the
formation of a blossom, yet without reaching the final formation,
that of the formation of the carpel. (Phenogams without real
fruit, gymnospermic Anthophytes.)

“TV. Plants which reach the final and highest conclusion of
vegetable development, that of true fructification. (Angiospermic
Anthophytes; Monocotyledons and Dicotyledons as secondary
gradations.)

°° As we have discussed in this chapter individual development
with reterence to historical development, we must also notice the
strange opposition to the doctrine of descent offered by KOlliker.
He has laid down his views in his ‘‘ Monographie der Penna-
tuliden,” and, in a separate pamphlet, bearing the title of “ Mor-
phologie und Entwickelungsgeschichte des Pennatulidenstammes,
nebst allgemeine Betrachtungen zur Descendenzlehre”’ (Frank-
furt, 1872). Whereas Darwinism derives the continuity and
harmony of the organic world from variability, natural selection,
heredity, and adaptation—in short, from palpable, visibly efficacious
causes—Kélliker is of opinion “that the same general formative
laws which govern inorganic nature hold good also in the organic
kingdom, and hence a common pedigree and a slow transformation
of one form into another are entirely unnecessary for the explana-
tion and comprehension of the accordance of the forms and series
of forms of the animate world” (p. 3). Except decided dualists, no
one disputes the first part of Kdlliker’s thesis. But the identifica-
tion of the development of the organic individual, excluding the
law of heredity, with the simple process of crystallization, or any
other operation of chemical combination repeating itself under
given conditions, scarcely needs a detailed refutation. Kolliker
says, and tries to prove, that the so-called monophyletic hypo-
326 THE DOCTRINE OF DESCENT.

thesis, according to which the different families of organisms are
derived from a single primordial form, has to struggle with insur-
mountable difficulties ; that the hypothesis of descent from many
families (polyphyletic) possesses more probability. If this be
admitted, then—and here comes a bold leap of the imagination—
the adherent of the polyphyletic hypothesis finds himself in a
position to attribute different pedigrees and primordial forms not
only to the higher divisions, but even to their genera, and to assume
their independent origin. Nay, it even seems credible that the
self-same species may appear in different pedigrees; as by the
incontrovertible supposition of general laws of formation, it cannot
be seen why like primary shapes should not, under certain circum-
stances, be able to lead to like final forms (see p. 21). Nay, this
hypothesis does more, for “‘ even if individuals of the same species
occupy remote localities, as, for instance, Pennatula phosphorea,
Funiculina quadrangularis, Renilla reniformis, &c., it is surely more
fitting to assume their independent origin.” Kolliker’s polyphyletic
hypothesis put an end to all difficulties, and, among others, it ex-
plains the so-called “‘ representative forms” to be mentioned in our
tenth chapter ; for, from ‘this standpoint, it is credible that these
forms are not genetically connected, but belong to different pedi-
grees’ (p. 23). And all this, and much more, is supposed to be
conceivable, because the world of organisms, in its consecutive
development, follows intrinsic causes or definite laws of formation,
“laws which, in a perfectly definite manner, urge on the organisms
to constantly higher development.” At the same time, Kolliker
deliberates (p. 38) whether, just as here germs and buds, so also
free existing youthful forms of animals did not possess the power
of striking out a development different from the typical one, which
freedom must be severely mulcted by the law of development,
which can and must create individuals of the same species at the
opposite poles, Kolliker (p. 44) thus sums up his fundamental
view—‘‘that in and with the first origin of organic matter and of
organisms, the whole plan of development, the collective series of
possibilities, were also potentially given, but that various external
impulses operated determinatively on individual developments, and
impressed a definite stamp upon them.” Notwithstanding the
REFERENCES AND QUOTATIONS. 327

scientific dress, dualism is here complete; whereas, Physics and
Chemistry make their laws, applying to inorganic as well as to
organic nature, comprehensible in their form, purport, and effects.
Kdlliker knows nothing of the constitution of his laws. The doctrine
of natural selection allows us to recognize the causes and effects of
heredity and adaptation, and establishes the phenomenal series un-
der the form of laws. But laws which are founded only on a plan
which is to be carried out prospectively and in subservience to this
dower of imperfect organisms, are ignored by natural science.

°° Ueber die Herkunft unserer Thierwelt. Einezoo geographische
Skizze von L. Riitimeyer (Basel, 1867). We have made* copious
use in our text of this extremely instructive writing.

7 A, R. Wallace, Malay Archipelago. P. 10, &c. See also his
remarkable and comprehensive work on the Geographical Distri-
bution of Animals.

™ G. Koch, Die indo-australische Lepidopteren-Fauna in ihren
Zusamnenhang mit den drei Hauptfaunen der Erde. (1 Ed., Ber-
lin, 1873.)

72 Peschl, Neue Probleme der vergleichende Erdkunde, 1870.

™ Unless we connect the Dinotherium with Mastodon and Ele-
phas, Between the pliocene Mastodon Borsoni and the Elephas
primigenius, twenty species are interposed, among which are our
still living species, the Indian and African elephants. The limits of
the two genera are hereby entirely obliterated. According to other
statements, the Elephas primigenius (the mammoth) falls into at
least four geographical varieties, which join on to the American
species. A dwarf species of elephant is found in the caves of
Malta, which in dentition attaches itself to the African species.

™ Joh. Schmidt, The Relationships of the Indo-Germanic Lan-
guages, 1872.

™ Various antagonists of the doctrine of descent have vented
their moral dismay in the most poignant expressions, precluding
any scientific discussion, on finding that the pedigree of the Verte-
brata, and therewith of man, is actually traced beyond the verte-
brated animals to so low a being as the Ascidians. It is otherwise
with the critics of Kowalewsky’s and Kupffer’s observations, who
acknowledge the facts, but think themselves obliged to differ in

22
328 THE DOCTRINE OF DESCENT.

their interpretation. One of these is A. Giard, in his work on the
“‘Embryogénie des Ascidiens.” (Archive de Zoologie expérimen-
tale, Paris, 1872.) The pupil of Lacaze Duthiers says :—“ La chorde
et l’appendice caudale sont chez la larve Ascidienne des organes de
locomotion d'un importance assez secondaire malgré leur généralité,
pour gu’on les vote disparaitre presque entzérement dans le genre
Molgula, ot ils sont devenus inutiles par suite des mceurs de |’ani-
mal adulte; l’homologie entre cette chorde dorsale et celle des ver-
tébrés n’est donc qu’une homologze d'adaptation déterminée a
remplir l’iodentité des fonctions, et n’indique pas de rapports de
parente immediate entre les vertébrés et les Ascidiens.”” The author
thus denies the consanguinity of the vertebrate animals and Ascid-
jians, and traces back to adaptation the resemblance approaching
identity occurring in the organs of the two. The inferences in these
few sentences appear to us utterly at fault. The circumstance that
in Molgula, and many other Testacea, development takes a nar-
rower course, makes as little alteration in the importance of the
facts as, for instance, the Nauplius development of the Peneus ob-
served by Fritz Miiller, or the Navicula of the Molluscs, is prejudiced
by the fact that the other Decapods have forfeited the Nauplius
phase, or the Landsnails the navicula phase. But it is simply in-
comprehensible in what the identity of functions is to consist which
in the Vertebrata was capable of producing the notochord, with, it
is particularly to be remarked, the spinal cord (which M. Giard
entirely forgets) ; and, in the other case, the ‘‘homologie d’adapta-
tion.’’ We, on the contrary, see these organs performing different
functions, because in the one they remain of fundamental impor-
tance through life, and not in the other. Thus we conversely lay
the stress on the morphological identity accompanying functional
difference. M. Giard adduces no facts.

7°T. H. Huxley, Manual of the Anatomy of the Vertebrated
Animals. German Ed.

™ March, American Journal of Sciences and Arts, February,
1873.

7 Eckermann, Gespriche mit Goethe. II. 152.

7 Rousseau, Emile (Euvres, Paris, 1820, IX. 17). ‘‘ Nous n’avons
point la mesure de cette machine immense; nous n’en pouvons
REFERENCES AND QUOTATIONS. 329

calculer les rapports; nous n’en connaissons ni les premiéres lois,
ni la cause finale ; nous nous ignorons nous-mémes ; nous ne con-
naissons ni notre nature, ni notre principe actif.’’

®° Metamorphose der Thiere.

* R, Valdek in the “ Presse,” 1865, No. 327.

* Huxley, Man’s Place in Nature, 1863. Manual of the Anatomy
of the Vertebrated Animals.

8° Broca, L’Ordre des Primates. Paralléle anatomique des
l'Homme et des Singes. (Paris, 1870.)

84 Waitz, Anthropologie der Dances 6 thl., p. 796. Bear-
beitet von Gerland.

8 Do. p. 708,

8 « Augsburger Allgemeine Zeitung,’’ 1873, Nos. 92-94. Beilage.

*' 1 heard the lectures delivered at Strasburg by this scholar,
“Ueber die Resultate der Sprachswissenschaft,”’ with great interest
and advantage. .

* L. Geiger, Der Ursprung der Sprache, 1869, p. 37.

8° Steinthal, Der Ursprung der Sprache, 1851.

°° Fr. Miiller, Allgemeine Ethnographie. Wen., 1873.
Agassiz, L. 11, 80, 86, 223.
Alca impennis, 186.
Amblystoma, 210.
Ammonites, 71, 74, 97.
Amniotes, 250.
Amphibians, 209, 258, 264.
Amphioxus. See Lancelet.
Anchitherium, 242, 273.
Ancyloceras, 216.

Anguis, 185.

Annelids, 32, 198.
Annulosa, 250.
Anoplotheride, 274.
Anteater, 246. :
Antelopes, 273, 277.

Apes, 280, 288,

Arachnida, 33.
Archzopteryx, 75, 266.
Archzosauros, 73.
Archegosauros, 259.
Armadillos, 228, 246.
Articulata, 32, 53, 72, 201, 219.
Ascarides, 206,

Ascidians, 35, 219, 252.
Axolotl, 209.

Baer, C. E. von, 48, 191, 197,
219, 293-

Balenide, 280.

Barrande, 11.

INDEX.

Bathybius, 26.
Batrachians, 72, 259, 264.
Bats, 228, 246, 269.
Bavey, 212.

Bears, 243.

Beaumont, Elie de, 130.
Beavers, 247.

Bees, 28, 47.

Beetles, 185.
Belemnites, 74.
Beneden, Van, 206.
Birds, 227, 232, 250, 265,
Bison, 277.

Blastoids, 77.

Bleek, 304.

Bos, 277.

Bourguignat, 224.
Brachiopoda, 7o.

Braun, 193, 220.

Brehm, 182, 267.

Broca, Prof. 160, 289.
Briicke, 27.

Bruta, 237, 271.
Bubalos, 277.

Buffaloes, 244, 247.
Buffon, 5.

201, | Butterflies, 227.
Cachelots, 279.
Cznopithecus, 245.
331

 
332

Camels, 223.

Camper, P. 101, 119,
Campsognathus, 264,
Canidae, 278.

Carnivora, 241, 273, 278.
Carpenter, Dr. 64, 93.
Cassowaries, 237.
Cassidulida, 77.

Cats, 100, 170, 234.
Cecidomyia, 47.
Cephalopoda, 70, 154, 201.
Ceratoda, 258.

Cercaria, 46.

Ceroxylus laceratus, 181.
Cestoda, 206,

Cetacea, 239, 273, 279.
Chalina, 152.

Chalinula, 152.
Cheiroptera, 280.
Chelonia, 263.
Chimpanzee, 283.
Chirotes, 185.

Cidaridez, 77.
Cirripedes, 207.

Civets, 234.

Cladonema Radiatum, 42, 202.

Clymenia, 71.
Clypeastra, 80.
Coccoliths, 26.
Ccckleshell, 199.
Ceecilia, 259.
Coelenterata, 32, 218.
Coleoptera, 184.
Comatula, 80, 197.
Conchifera, 71.
Copepoda, 207.

Corals, 42.

Crabs, 150, 153, 207, 210, 238.
Credner, 65.

Crinoid, 57, 77-
Crocodiles, 75, 260, 262.
Crossopterygii, 258.
Ctenomys, 184.

 

INDEX..

Curtius, G. 304.
Cuscus, 234.
Cuttlefish, 33.
Cuvier, 30, 85.
Cyclostomi, 256.
Cytisus, 146.

Darwin, 131, 183, 248.
Deciduata, 272.

Deer, 234, 246, 275. ,
Delphinoidz, 279.
Dentalium Teredo, zoo.
Desor, 76.
Dicynodonta, 260.
Didelphidz, 245.
Dinosauria, 261.
Dinotherium, 295.
Dipnoi, 37, 256, 258.
Distoma, 46, 206.
Dodo, 186.

Dogs, 99, 138.
Dubois-Reymond, 15, 20.
Duck-mole, 237.
Dujardin, 42.

Dumeril, A. 209.

Earl, G. Windsor, 230.
Echidna, 270.

Echinidz, 76, 80.
Echinoconide, 77.
Echinodermata, 32, 76.
Edentata, 79, 237, 246, 269, 271.
Elasmobranchii, 256.
Elephants, 80, 231, 242, 247, 265, 310
Enaliosaurians, 74, 238.
Endocyclica, 77.

Eozoon, 68.

Ephippigera vitium, 172.
Eucladia Johnsoni, 76,

Feather stars, 76.
Fick, A. 18,
Fish, 258, 264.
INDEX.

Foraminifera, 93.
Foster, G. 101,
Fowls, 135.
Frogs, 259.
Firbringer, 185.

Ganoids, 71, 256,
Gargol, 44.
Gasteropoda, 70,
Gastrula, 51, 218, 221.
Gegenbauer, 74, 256.
Gerland, 300.
Gibbon, 289.
Giraffes, 277.

Goats, 277.

Goethe, 106.
Gorilla, 288.

Graber, Von, 171.
Graminivora, 240,
Graptolites, 69.
Gratiolet, 291.
Guinea-pig, 100.

Heckel, 40, 89, 177, 198, 218, 250.
Heer, 238.

Heliconidz, 179.

Helladotherium, 277.

Herder, 4.

Hilgendorf, 96.

Hipparion, 275.

Hippopotamus, 243, 276.
Holothuria, 78, 197, 219,
Honeysuckers, 233.

Horses, 81, 170, 225, 242, 273, 295.
Humboldt, W. von, 4, 222.
Huxley, 257, 264, 289.
Hydractinea carnea, 203.

Hydra tuba, 178.

Hydrophilus piceus, 53.

Hyenas, 243, 278.

Hylodon Martinicensis, 212.
Hypsilophodez, 265.

Hyrax, 269, 278.

 

333

Ichthyornis dispar, 267.
Ichthyosauria, 74, 260.
Inflata, 216,

Insecta, 33.
Insectivora, 269, 280.

Kangaroos, 233.

Kerner, 146.

Korte, Dr. 117.
Kowalewsky, 199, 219, 251.

Labyrinthodonta, 72.
Lacertilia, 262.

Lama, 223, 245.

Lamarck, 117, 124, 147.
Lamellibranchiata, 1¢9.
Lancelet, 36, 150, 219, 251.
Laplace, 15.

Leibnitz, 3."

Lemurs, 269, 280.
Lepidosirens, 37, 238, 258.
Leptalidz, 180.
Leptotherium, 245.
Linnzus, 5, 84,

Lions, 223.

Lizards, 185, 261.

Locke, 303.

Lories, 233.

Lucca, 286.

Luthardt, 12.

Lyell, Sir C. 128.

Machairodus, 242.

Macrauchenide, 275.

Madrepores, 42.

Mammals, 73, 240, 250, 264, 269, 277.
Mammoths, 79, 244, 247.

Man, 111, 201, 269, 288.

Mantida, 181.

Marsh, 267.

Marsipobranchii, 256.

Marsupial frog, 212,

Marsupials, 73, 75, 228, 238, 240, 269.
334

Martens, 241.

Mastodon, 80.

Maupertuis, 4.

Maury, 227.

Mayer, Ernst, 118,
«+Medusz, 31, 203, 210, 218.
Megalonyx Jeffersoni, 246.
Mollusca, 33, 199.
Monera, 27.

Monkeys, 79, 234, 269.—See Apes.

Monotremata, 2€9.
Miller, Friedrich, 305.
Miller, H. 299.
Miller, Johannes, 279.
Miller, Max, 161, 303.
Miller, Fritz, 207, 238.
Musk animals, 242.
Mylodon Harlemi, 245.
Myriapoda, 33.
Myxine, 259.

Nageli, 160, 193.

Nathusius, H. von, 175, 178.
Naumayr, 97.

Nauplius, 207, 210.
Navicula, 199.

Nematoids, 205.

Oken, 1c5.

Ophiura, 198.
Opossums, 233, 245.
Orang, 288.
Orniscelidz, 260.
Ornithorhyncus, 37, 237, 270.
Orthoptera, 171.
Ostrich, 237.

Quistitis, 291.

Ovibos, 277.

Owen, R. 121, 193, 290.
Oxen, 247, 275.
Oysters, 202,

Pachyderms, 79, 240, 243.
Palzochceride, 244.

 

INDEX.

Paleoniscus, 71.
Palzotheride, 273..
Paludina, 200.

Pander, 219.

Pavians, 289.

.Peneus, 208.

Petromyzon, 256.
Phasmide, 181.
Physeteridz, 280.

Pigs, 175, 178, 242, 244, 275.
Pigeons, 133, 170, 177.
Pinnipedea, 278.

Placoids, 71.

Planorbis multiformis, ¢6.
Platelmintha Suctoria, 206,
Platypus, 233.
Plesiosaurians, 74, 269.
Pleuronectidz, 181.
Polecats, 241.

Polistes Gallica, 47.
Polypes, 28, 30, 174, 203, 218.
Polypterus, 258.

Primates, 308.

Proboscide, 273.
Protamceba, 26, 40.
Proterosaurus, 73.

Proteus, 259.

Protopterus, 238, 258.
Pseudopus, 185.
Pterodactyls, 75, 250, 263, 256.
Pterotrachea, 199.
Pulmo-gasteropoda, 224.
Puma, 223.

Quadrumana, 245.

Radiata, 31.

Rathke, 55.

Regulara, 77.

Reniera, 94, 153.

Reptiles, 250, 264.

Rhabdoliths, 26.

Rhinoceros, 231, 242, 247, 273, 310.
INDEX.

Rhizopoda, 207.

Rodents, 246, 269, 278, 280.

Rollet, 26, 168,

Rousseau, J. J. 4.

Ruminants, 79, 240, 277.

Ritimeyer, 81, 223, 227, 236, 257, 273,
277+

Sagitta, 37, 219.
Sahuis, 289.

Saint Hilaire, E.G. 85.
Salamanders, 209, 211, 259.
Salmon, 239.

Sauria, 260.
Sauropsida, 264.
Scaphites, 75.
Schleicher, 304.
Schmidt, Johannes, 249.
Schulze, Max, 154.
Sea-cows, 277.
Sea-cucumbers, 78, 197.
Seals, 269.

Sea-snails, 199.
Sea-urchins, 76, 197.
Semper, 42.

Serpents, 260.

Sheep, 136, 244, 277.
Shrimp, 207.

Siebold, Von, 47.
Sirens, 239, 269, 277.
Sivatherium, 277.
Sloths, 228, 246.

Snails, 224.

Snakes, 185.

Spatange, 77, 80.
Spongiade, 30, 93, 218.
Squalodon, 279.
Starfish, 76, 197.
Stauridium, 42, 202.
Stein, 41.

Steinthal, 304.
Stone-lilies, 76, 80.
Strauss, D. F. 302.

 

335

Sturgeons, 238.
Suctoria, 206,
Suida, 276.
Surinam toad, 212.
Siissmilch, 4.

Tapeworm, 43, 206.
Tapirs, 231, 242, 273.
Tedania, 94.
Teleostei, 256.
Termites, 178.
Tesselle, 77.
Testacea, 250, 255.
Tetrabranchiata, 1¢9.
Thompson, W. 64.
‘Threadworms, 200.
Thrushes, 234.
Tiger, 242.

Toenia solium, 44.
Tortoises, 75, 238, 260, 263.
Tragulidz, 275.
Trematoda, 206.
Trilobites, 69.
Tritons, 209, 260.
Trogons, 234.
Tuco-tuco, 184.
Turbellaria, 37, 45, 206.
Turrilites, 75.

Unger, F. 72.
Ungulates, 240, 242, 259, 273, 278.
Ursidez, 278.

Verany, 182.

Vermes, 32, 201.

Vertebrata, 33, 154, 186, 250, 264.
Viverrida, 241, 278.

Wagner, M. 158, 302.
Waitz, 300.

Wallace, 164, 230.
Walruses, 279.
330 INDEX.

Watson, H. C. 151. Worms, 205.

, Werner, 129. Wirtenberger, 96, 213.
Whales, 269, 280.
Wolves, 100. Zeuglodon, 279.

’ Wombats, 233. Zoea, 208.
Woodpeckers, 234. Zoliner, 21, 162.

THE END.
 
arV1696 Cornell University Ubrary

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