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THE

ORIGIN OF THE FITTEST

ESSAYS Olf EYOLUTIOjN"

E. D. COPE, A. M., Ph. D. (Heidelberg)

MEMBER OF THE UNITED STATES NATIONAL, ACADEMY OF SCIENCES ; CORRESPONDENT OP

THE ROYAL BAVARIAN ACADEMY OF SCIENCES

KKW YORK
D. APPLETON AND COMPANY

1887

COPTKIGHT, 1S86,

By D. APPLETON AND COMPANY.

TO MY FRIEND

PROFESSOR ALPHEUS HYATT,

OF BOSTON, MASS.,
WITH WHOSE STUDIES MY OWN HAVE LONG BEEN PARALLEL,
AND WITH WHOSE CONCLUSIONS I HAVE LONG COINCIDED,
THIS WORK IS DEDICATED

THE AUTHOR.

146933

PEEFAOE.

The tu^enty-one essays which constitute the present volume represent
the reflections which have suggested themselves to the author while engaged
in special zoological and paleontological studies. While the original work
of the author has been nearly confined to the vertebrata, his studies have
taken in a wider range. These have convinced him that the conclusions
derived from the investigations of the vertebrata are applicable to inverte-
brate animals and to plants.

In reaching conclusions, the author has endeavored to avoid, as much
as possible, any bias due to the influence of any opinions whatsoever on
evolution and allied subjects which were already in the field. He therefore
avoided, for a time, reading the works of the masters of the subject, apply-
ing to them for confirmation or criticism only after the publication of his
own results. It is therefore true that the generalizations contained in these
essays have been worked out by the author from such material as has come
under his own eyes, with little other aid. It has also followed that not a
few of the conclusions he has reached were not new. On the other hand,
some of the principles enunciated had not been clearly stated prior to the
publication of these essays. In some cases the work accomplished has con-
sisted in throwing well-known principles into accord with each other, as in
the case of the laws of acceleration and retardation.

The earlier essays are the more hypothetical, and the later present more
numerous demonstrations. The latter have resulted chiefly from the author's
researches in the field of vertebrate paleontology, which have thrown the
greatest possible light on the fact and method of evolution. For the his-
tory of this subject the reader is referred to the author's forthcoming
*'• Manual of the Vertebrate Paleontology of North America ''' ; and, for the
more detailed work, to the author's publications in the " Final Reports of
the United States Geological Surveys," under "Wheeler and Hayden, and
to the "Proceedings of the American Philosophical Society of Philadel-
phia."

The present essays are arranged (see table of contents) into four series,
as follows : First, on General Evolution ; second, on the Structural Evidences
of Evolution ; third, on Mechanical Evolution ; fourth, on Metaphysical Evo-
lution. In the first series the author's earlier essays are arranged. The
general principles are here laid down or foreshadowed. The essays of the

vi PREFACE.

succeeding sections are occupied with the demonstration of these and other
generaUzations, so far as practicable. In each of the sections some essays
will be found to be more, and others less, adapted to popular use. It
is believed that the general reader can select a sufficient number of articles
of minimum technicality to convey to his or her mind a sufficient idea
of the views set forth. In Part I, articles first, fourth, and sixth are of
this character. In Part II, the first, second, and third essays are the
least technical. In Part III, the first article is the most popular, although
tbe others are essential to an understanding of the doctrine of mechani-
cal evolution. In Part IV, all are sufficiently popular for the reader who
has some knowledge of mental science.

A historical synopsis of the essays may be now given. The attempt is
made to point out the aim of each, with an indication of what may have
been new in its contents. They are taken up in the order of date of pub-
lication ;

II. The Origin of Geneea. From the "Proceedings of the Philadel-
phia Academy of Natural Sciences " for October, 1868, and published sepa-
rately by the author early in 1869. In this essay the following doctrines
were taught :

First, that development of new characters has been accomplished by an
acceleration or retardation in the growth of the parts changed. This was
demonstrated by reference to a class of facts, some of which were new, which
gave ground for the establishment of the new doctrine.

Second, that oi exact parallelism between the adult of one individual or
set of individuals, and a transitional stage of one or more other individuals.
This doctrine is distinct from that of inexact parallelism which had already
been stated by von Baer. And that this law expresses the origin of gen-
era and higher groups, because —

Third, they can only be distinguished ly single characters when all their
representatives come to be known.

Fourth, that genera and various other groups have descended, not from
a single generalized genus, etc., of the same group, but from corresponding
genera of one or more other groups. This was called the doctrine of
homologous groups.

Fifth, the doctrine that these homologous groups belong to different
geological periods, and.

Sixth, to different geographical areas, which, therefore, in some in-
stances, are.

Seventh, related to each other in a successional way like the epochs of
geological time.

Of these doctrines it may be observed that the first and second are now
the common property of evolutionists, and are recognized everywhere as
matter of fact. The names which I selected to express them have, however,
only come into partial use. The author believes that, although the doctrine
was vaguely shadowed out in the minds of students prior to the publication
of this essay, it had not previously been clearly expressed, nor been reduced

PREFACE. ^i[

to a demonstration. Of the trnth of the doctrine the author is more
than ever convinced, and he believes that paleontological discovery lias
demonstrated it in many instances, and that other demonstrations will fol-
low. The fourth proposition (that of homologous groups) is now held
as a hypothesis explaining the phylogeny of various groups of animals.
For the descent of one homologous group from another, the term poly-
phyletic has been coined. It remains to be seen whether the doctrine
is of universal application or not. That homologous groups belong to
different geological horizons, as stated under the fifth head, has been
frequently demonstrated since the publication of the essay. That the sixth
proposition is true in a certain number of cases is well known, and it
follows that the seventh proposition is alsd true in those cases. The
latter hypothesis, which was originally advanced by Prof. Agassiz, is, how-
ever, only partially true, and the advance of paleontological study has not
demonstrated that it has had a very wide application in geological time.

A proposition which was made prominent in this essay was, that the
prevalence of non-adaptive characters, in animals, proves the inadequacy of
hypotheses which ascribe the survival of types to their superior adaptation
to their environment. Numerous facts of this kind undoubtedly indicate
little or no activity of a selective agency in nature, and do point to the
existence of an especial developmental force acting by a direct influence on
growth. The action of this force is the acceleration and retardation ap-
pealed to in this paper. The force itself was not distinguished until the
publication of the essay entitled '' The Method of Creation " (No. V), where
it was named growth-force, or bathmism. The energetic action of this force
accounts for the origin of characters, whether adaptive or non-adaptive, the
former differing from the latter in an intelligent direction, which adapts
them to the environment. The numerous adaptive characters of animals
had by that time engaged the attention of the author, and he found that they
are even more numerous than the non-adaptive. Some of the latter were ac-
counted for on the theory of the " complementary location of growth-force."

IV. The Hypothesis of Evolution, Physical and Metaphysical.
" Lippincott's Magazine," Philadelphia, 1870 ; reprinted by Charles C. Chat-
field & Co. New Haven, 1870.

This essay embraces a popular exposition of the principles maintained in
the essay entitled the " Origin of Genera," with some conclusions derived
from the general facts of anthropology. To this were added some facts in
the evolution of human physiognomy and human character, which had not
been previously thrown into harmony with the laws already set forth. Un-
fortunately, the author attempted to correlate these again with the theories
of some theologians, and, in some instances, without success. A few
paragraphs have been stricken from this part of the essay, and others are
allowed to remain as illustrations of far-reaching hypotheses resting on
little information.

V. The Method of Creation of Organic Types. From the "Pro-
ceedings of the American Philosophical Society," December, 1871 ; repub-

viii PREFACE.

listed by McCalla & Stavely the same year. Read before the American
Association for the Advancement of Science, at Detroit, August 27, 1871.
Received the Walker prize of the Boston Society of Natural History.
In this essay were added to the preceding, the following hypotheses:
. 1. The law of repetitive addition, in which the structures of animals
were shown to have originated from simple repetitions of identical ele-
ments.

2. The existence of an especial force which exhibits itself in the growth
of organic beings, which was called growth-force, or bathmism,

3. That development consists in the location of this energy at certain
parts of the organism.

4. That this location was accomplished by use or effort, modifying and
being modified by the environment; or the doctrine of kinetogenesis.

5. That the location of this energy at one point causes its abstraction
from other points, producing "complementary diminution" of force at the
latter.

6. That the location of this energy, so as to produce the progressive
change called evolution, is due to an influence called " grade influence."

7. That inheritance is a transmission of this form of energy, which builds
in precise accord with the sources from which it is derived.

8. That this " grade influence " is an expression of the intelligence of
the animal, which adapts the possessor to the environment by an " intel-
ligent selection."

9. An attempt to account for the origin" of " mimetic analogy " by
"maternal impressions."

On these propositions, the following comments may be made : First,
the law of repetitive addition is much like the law of rhythm previously pro-
posed by Herbert Spencer.* Second, the force of growth, or bathmism,
had already been called constructive force by Carpenter, who, however,
did not treat of its evolutionary or " grade " characteristics. That such
force exists there can be no doubt at the present time, but it may be that
its varied aspects should each be considered a separate species of force (i. e.,
energy). Third, the relations of the energetic and static conditions of this
force were considered, but were not sufficiently followed out to be clear.
It is hoped that greater clearness has been attained by the omission of
a few paragraphs and the insertion of an explanatory foot-note.

Fourth, that the location of this energy is due to the influence of use
and effort. The doctrine of the development of parts of living beings by
use, and their loss by disuse, is well known to have been put forth by
Lamarck in 1809, who devotes one of the longest chapters (No. VII) of his
" Philosophic Zoologique " to its discussion. He did not, however, include
the element of efort, prior to the appearance of any rudiment of an organ,
in his hypothesis, which was proposed, so far as I know, for the first time
in the present essay. The doctrine of use and disuse has been sustained

* «

Principles of Biology.'*

PREFACE. ix

by Spencer in his " Principles of Biology " as respects the effect of motion
on structure in general,* and in the particular case of the origin of verte-
brsB.t Fifth, the complementary development of parts had also been
pointed out by Herbert Spencer,!

Seventh, tlie explanation of inheritance by the transmission of the type
of growth-force possessed by one generation to another. This doctrine was
subsequently announced by Haeckel, under the name of perigenesis,^
and is the only good hypothesis yet proposed for the explanation of this
phenomenon. Eighth, the theory of "intelligent selection,"- or the agency
of the intelligence of a living being in directing its movements, and there-
fore its growth, although a plain and necessary consequence of the " law of
use and effort," had not been, so far as I am aware, announced prior to
the publication of this paper. This important theory at once opened the
way for an investigation of the general relations of mind to evolution, which
involved the question of the origin and development of mind itself. These
questions were more fully discussed in the papers of Part IV, on " Metaphys-
ical Evolution." Ninth, the origin of mimetic analogy. The explanation
offered is almost necessary, if the doctrine of the influence of effort on struct-
ural growth be true.

I. Evolution and its Consequences, From the *' Penn Monthly Maga-
zine," Philadelphia, for May, July, and August, 1872,

This is a popular exposition, with elaboration, of the doctrines contained
in the preceding essays. The evolution of mind is more fully stated, the
hypothesis adopted being that proposed by Spencer in his " Principles of
Psychology," published in 1855.

VII. The Homologies and Origin of the Types of Molar Teeth
OF THE Mammalia Edtjcabilia. From the " Journal of the Academy of
Natural Sciences," Philadelphia, March 30, 1874.

The object of this paper was to show that the various more or less com-
plex types of molar "teeth displayed by the Ungulate Mammalia are referable
to modifications of a primitive quadituberciilar type, from which they were
supposed to have been descended. The histories and homologies of the
carnivorous dentitioa were not included in this paper. In order to com-
plete the subject, I have inserted brief notes of the conclusions I have since
attained in this field : first, as to the type of inferior sectorial teeth, in 1875 ;
and, second, as to the superior molars, in 1883.

At the end of the paper a similar- comparison between the feet of the
same type of mammals is made, and general conclusions reached in the fol-
lowing language : " I trust that I have made it sufiiciently obvious that the
primitive genera of this division of mammals [Mammalia Educabilia = Un-
guiculata and Ungulata sensu lata] must have been bunodonts with penta-
■daetyl plantigrade feet."

Vol. ii, p. 167. t Vol. ii, p. 195. X " Principles of Biology."

* See Ryder, "American Naturalist," January, 1879.

X PREFACE.

The nearest approaches to a similar anticipation on the part of other
naturalists, which I have been able to find, refer to the number of toes only,
and are of restricted application. Thus Kowalevsky remarks (" Monographie
der Gattung Anthracotherium, Palaeontographica," xxii, p. 1452) : "• So we
can assume a tetradactyl foot as our point of departure, although it can
not have the least effect on the result in case the original ungulate foot
should have been pentadactyl. If I have set out with a tetradactyl foot
it is simply because I wish to adhere so far as possible to facts." This was
written August, 1873, but how soon thereafter it was printed I do not know.
I did not meet with it until at least a year after the publication of my paper
of March, 1874, cited. Secondly, Marsh, in writing on the genealogy of
the horses ("American Journal of Science and Arts," March, 1874, p. 257),
says : " A still older ancestor [of the horse], possibly in the Cretaceou?,
doubtless had five toes on each foot, the typical number in mammals." My
paper was published during the same month as the above; but I communi-
cated the substance of the generalization in question to the Philadelphia
Academy the day it was read, November 18, 1873, which was published in
the "Proceedings of the Society," January 13, 1874, p. 2.

XYIII. Consciousness in Evolution. From the " Penn Monthly Maga-
zine," Philadelphia, July, 1875.

In this paper the doctrine of intelligent selection is analyzed, and the
problem reduced to its essential — the relations of consciousness to matter.
The doctrine of the origin of reflex and automatic acts from conscious states,
or archaesthetism, is here first proposed. From the characters of proto-
plasm the inference is derived that that substance is not necessarily the only
one capable of supporting consciousness. The author is not aware of any
previous attempt to render these propositions probable.

VIII. The Relation of Man to the Teetiaey Mammalia. From the
" Penn Monthly Magazine," December, 1875. Read before the American
Association for the Advancement of Science, at Detroit.'

The fact that the hard tissues, and probably the digestive system, of man,
are constructed on the type of the Mammalia of the early Eocene period
is here pointed out for the first time.

III. The Theoey of Evolution. Remarks made before the Academy
of Natural Sciences of Philadelphia, February 22, 1876, and published in the
"Proceedings of the Society," 1876, p. 15.

These remarks exhibit the correspondence between the evolutionary
systems of Haeckel and of the writer, and combine them into a symmetricid
whole.

XXI. The Oeigin of the Will. From the "Penn Monthly Magazine,"
Philadelphia, June, 1877.

In this paper the attempt is made to render the existence of freedom of
will probable by a process of argument, and also to demonstrate its exist-
ence by another kind of argument. As is well known, there are two op-
posed doctrines respecting this important question. One of these, which
has by far the larger number of adherents, is that the human mind embraces

PREFACE. xi

among its powers a freedom of will, or spontaneity in action. The other
view is, that there is no such power, but that the actions are merely the
necessary result of the strongest pressure of the strongest inducement or
motive. The doctrine of evolution is known to lend support to the latter
doctrine. In the present paper the attempt is made to prove that free will
is a new power which supervenes on the process of evolution. This is done
by assuming the existence of a class of acts for which the term altruistic is
retained, which, undoubtedly, would require freedom for their perform-
ance. The only question here is, whether there be any such class of acts as
are defined under the above name in this essay. If tliere be no such class
of acts, the demonstration based on it falls to the ground ; and the author
is xiot at present sure whether there be such a class of acts or not.

The argument by which freedom of will is rendered probable is not
open to any serious objection, and rests on the necessity for action which
sometimes arises in cases where there is no experience or knowledge to serve
as a determining motive or power. These cases are supposed to involve
moral questions. The doctrine is then intermediate between the two oppos-
ing ones which have long divided the world of thought,* It permits of the
development of a free will in previously automatic beings, as a phenomenon
superposed on mental evolution. The argument demonstrates nothing more
tlian that freedom is possible; a conclusion which is, however, important,
since it shows that the position of the determinists is not impregnable,

XII. The Relation of Animal Motion to Animal Evolution. From
" The American Naturalist," January, 1878. Read before the American
Association for the Advancement of Science, at Nashville, August, 1877.

The effects of the actions of animals on their structure are considered,
as in previous papers, and especial attention is paid to the influence of ani-
mals in the changes they produce in their environment.t

XI Y. The Origin of the Specialized Teeth of the Carnivoea. From
" The American Naturalist," March, 1879.

The mechanical reasons for the changes in the dentition of carnivorous
mammals during geologic time are pointed out for the first time.

VI. A Review of the Modern Doctrine of Evolution. From "The
American Naturalist," March and April, 1880. A lecture delivered before
the California Academy of Sciences, October 27, 1879. It is a general
synopsis of views presented in preceding papers.

XY. On the Origin of the Foot-Structure of the Ungulates.
From " The American Naturalist," April, 1881.

This essay embraces an explanation of the cause of the diminution of the
number of digits in the diplarthrous ungulate mammals ; of the reasons
why some are even- and some odd-toed ; and of the origin of some of the

* This view is adopted by President Xoah Porter in one of his latest metaphysi-
cal works.

f A synopsis of the relations of animals to their environment is given by Spen-
cer, " Principles of Biology," vol. i, p. 466.

xii PREFACE.

articulations of the tarsus. These explanations, so far as based on paleonto-
logical grounds, were new at the time.

XVI. The Effect of Impact and Steains on the Feet of Mammalia.
From " The American Naturalist," July, 1881.

The origin of the structures of all the articulations of the limbs of all the
Mammalia are explained as the effects of impacts and strains.- The demon-
stration is based largely on paleontological evidence, and is new.

XIX. On Aechaesthetism. From " The American Naturalist," June,
1882.

This doctrine is discussed and illustrated on the basis laid down in the
essay " Consciousness in Evolution," and a classification of theories of crea-
tion is presented.

IX. The Developmental Significance of Human Physiognomy. From
"The American Naturalist," June, 1883.

In this paper suggestions presented in Art. IV, entitled "The Hypothe-
sis of Evolution, Physical and Metaphysical," are developed, and the physical
significance of the form-characters of men in general are considered. Noth-
ing except reference to a few leading points of the subject had been pub-
lished prior to this paper, so far as the author has been able to discover. In
connection with a paper on the "Evolutionary Significance of Human Char-
acter," a foundation was laid for a scientific physiognomy.

X. The Evidence foe Evolution in the Histoey of the Extinct
Mammalia. A lecture delivered before the American Association for the
Advancement of Science, at Minneapolis, August, 1883.

In this paper are collected the evidences of descent displayed by the
Mammalia (and in one instance by the Batrachia), as derived from the pale-
ontological researches of the author. These had been in some points fore-
shadowed in the author's memoir on the homologies and origin of the struct-
ure of the molar teeth in the Mammalia Educabilia in 1874, which were
here shown to have been realized by subsequent discovery, and a number
of other evidences added. Restatements of the laws of kinetogenesis, and
of the origin of morals, were made.

XVII. The Evolutionaey Significance of Human Chaeactee. From
the " American Naturalist," September, 1883,

The characters of the adult mind are compared with those of the child,
and with those of the lower animals, and the direction of their evolution
pointed out. Most of the propositions contained in this paper were new at
the time of its publication.

XIII. The Teituberculae Type of Molae Teeth in the Mammalia.
From the proceedings of the American Philosophical Society, 1883, page
324;* published in advance in the "Paleontological Bulletin," No. 37,
January 2, 1884.

The origin of the ungulate molar tooth had already been traced to a
quadritubercular type in paper No. VII (March and January, 1874). The

* Not published until 1884.

PREFACE. xiii

present paper shows that this type in the upper jaw is a derivative of a tri-
tubercular type, while that of the lower jaw is a derivative of a quinquetu-
bercular type, or a tritubercular type with a heel, which may support two
additional tubercles. The tritubercular type was again traced to the sim-
ple cone. This generalization was new at the time of publication.

XX. Catagenesis. Vice-presidential address delivered before the bio-
logical section of the American Association for the Advancement of Sci-
ence, Philadelphia, September 4, 1884.

The hypothesis of catagenesis which is put forth in this paper teaches
that primitive energy was and is conscious, and that all unconscious forms
of energy, whether "vital" or non-vital, have been derived from it by a
process of retrograde metamorphosis. The first stage of this retrogression
is the loss of consciousness, or cryptopnoy. Evidence for this kind of meta-
morphosis is derived from every-day experience, and from the designed
character of automatic acts. That a form of energy is conscious is inferred
from the nature of designed conscious acts of animals. The author had not
met with any scientific statement of this theory prior to the preparation of
this lecture.

XI. The Evolution of the Yeetebeata, Progeessive and Reteo-
GEESsivE. From the "American Naturahst," February, March, and April,
1885.

This paper sets forth the results of paleontological investigation of the
Vertebrata, in a series of phylogenies. These are, first, the phylogeny'
of the classes ; then the special phylogenies of their contents or of the
orders. Here are introduced the newly-discovered relations of the Anti-
archa and the Ichthyotomi to the fish-like vertebrates, and of the thero-
morphous reptiles to the Mammalia. Also, the ancestral relation of the
Theromorpha to most other reptiles, and of the Condylarthra to the placental
Mammalia, and to man. Many of the other results set forth in this essay
are derived from the paleontological researches of the author. Some of
them, especially the lemurine (condylarthrous) ancestry of the placental
Mammalia, had been anticipated on theoretical grounds by Haeckel in his-
" History of Creation " (" Schopfungsgeschichte "). Haeckel was very
general in his proposition, and did not anticipate the details of the demon-
stration. My investigations enabled me to produce these, which bring out
in a striking manner the sagacity of Prof, Haeckel. I consider further the
question of degeneracy, and the significance of the phylogeny with refer-
ence to this subject is pointed out.

In conclusion, it may be said that the principal object which the author
set before him, in the studies here recorded, has been the discovery of
the laws of variation, or of the " Origin of the Fittest." These essays
express the light which he has been able to obtain on this difficult question
up to the present time. The results could be better and more briefly pre-
sented in a systematic form, but the author reserves this for a future occa-
sion.

COH'TENTS.

PART I.— GENERAL EVOLUTION.

L — Evolution and its Consequences

IL — The Origin of Genera

in. — The Theory op Evolution

IV. — The Hypothesis op Evolution, Physical and Metaphysical

V. — The Method of Creation of Organic Forms .
VI. — Review of the Modern Doctrine of Evolution

PAGB

1
41

124
128
173

215

PART IL— STRUCTURAL EVIDENCE OF EVOLUTION.

VII. — The Homologies and Origin of the Types op Molar Teeth of the

Mammalia Educabilia 241

VIII. — The Relation of Man to the Tertiary Mammalia . . . 268

IX. — The Developmental Significance op Human Physiognomy . . 281
X. — The Evidence for Evolution in the History of the Extinct

Mammalia 294

XI. — The Evolution of the Vertebrata, Progressive and Retrogres-
sive 314

PART IIL— MECHANICAL EVOLUTION.

XII. — The Relation of Animal Motion to Animal Evolution . . 350

XIII. — On the Trituberculate Tooth in the Mammalia .... 359

XIV. — The Origin of the Specialized Teeth of the Carnivora . . 363

XV. — The Origin of the Foot Structures of the Ungulates . . 368

XVI. — The Effect of Impacts and Strains on the Feet of Mammalia . 373

xvi COITTEN'TS.

PART IV.— METAPHYSICAL EVOLUTION.

PAGE

XVII. — The Etolutionary Significance of Human Character . . 378

XVIIL — Consciousness in Evolution 390

XIX. — Arch>esthetism 405

XX. — Catagenesis 422

XXI.— The Origin of the Will 437

LIST OF ILLUSTEATIOI^S.

Plates.

PLATE PAGE

I. Figures and Diagrams of the Circulatory Centers of Vertebrata. Copied

from Gegenbaur and His, mostly enlarged 60

II and Ila. Figures of Lizards of the families Iguanidae and Agamidae

compared 9*7

III and Illa. Mimetic analogy in the colors and patterns in snakes of dif-
ferent genera and species 105

ly and V. Series of Crania of Different Families of Tailless Batrachia

showing similar stages of development. Original . . . 220, 221

Explanation 222

VI. Succession of Modifications of Feet of Diplarthrous Ungulata. Original 271
VII. Succession of Dental Forms, mostly of LTngulata. From Gaudry, Wort-
man, and Cope 275

VIII. Uintatherium eornutvm Cope, restored, one twenty-seventh natural size.

From Cope, Marsh, and Osbom 277

IX. Anaptomorphus and Homo ; Cranium, Brain, and Teeth. Original, ex-
cept Figs. 8 and 9 from Allen 279

X. Esequibo Indians. From photographs by Endlich .... 286

XI. The Wrestler. From the Vatican . . .... 289

XII. Venus of the Capitol 292

XIII. Phenacod^is primcevus Cope, Skeleton as found in matrix, one seventh

natural size. Original ......... 300

XIV. Brains of Extinct Mammalia. Original, except Fig. 2 from Marsh . 308
XV. Diclonius mirabilis, Skull Profile. Original 338

XVI. Diclonius mirabilis, Skull from below, one half the mandible removed . 339
XVII. Phenacodus vortmani, Skeleton as found in Matrix, two ninths natural

size. Original 345

XVIII. Hycenodon horridus Leidy, Skull one half natural size. From Lcidy . 364

Wood-Cuts.

FIG.

1. Diagram illustrating acceleration and retardation 10

2. Diagram illustrating relations of genera of batrachia anura . . .80
3 to 6. Diagrams illustrating development of genera of batrachia anura . 81
7. Same as Fig. 1 . , 1*76

XVlll

LIST OF ILLUSTRATIONS.

FIG.

8. Sternum and adjacent parts of Scaphiopus Jiolbrooki ....

9. Sternum of Tadpole of Rana temporaria ......

10. Sternum of adult Rana temporaria .......

11. Metacarpus, carpus, and distal extremity of radius of Poehroiherium vihoni

12. The same, less radius, with first phalanges of Procamelus occidentalis

13. Skull of Protolahis transmontanus

14. Skull of Procamelus occidentalis .

15. Tooth of Globicephalus ....

16. Tooth of Jaculus hudsonicus

17. Tooth of Leploch(e7'us spectabilis. From Leidy

18. Tooth of Rhinocerus, milk superior molar .

19. Tooth of Achcenodon insolens

20. Tooth of Hippopotamus amphibius. From Cuvier

21. Tooth of Hyopotamu^ velaunus. From Blainville
2 1. Tooth of Hyopotamus americanus. From Leidy

23. Tooth of Procamelus robustus. From Leidy

24. Tooth of Merychyus major. From Leidy .

25. Tooth of Tapirus .....

26. Tooth of Mastodon angustidois. From Cuvier

27. Tooth of Mastodon americanus. From Cuvier

28. Tooth of Dinotherium. From Cuvier

29. Tooth of Elephas indicus. From Cuvier .

30. Tooth of Microsyops elegans. From Leidy

31. Tooth of Hyopsodus paulus. From Leidy .

32. Tooth of Palceosyops kevidens. From Leidy

33. Tooth of Ancldppodus riparius. From Leidy

34. Tooth of Palceosyops vallidens. From Leidy

35. Tooth of Pcdceotherium. From Cuvier

36. Tooth of Hipposyus. From Leidy

37. Tooth of Hipposyus more worn. From Leidy

38. Tooth of Hypohippus. From Leidy .

39. Tooth of Equus, superior molar. From Leidy

40. Tooth of Equus, inferior molar. From Leidy

41. Tooth of Baihmodon radians

42. Tooth of Uintatherium robustum, superior molar.

43. Tooth of Uintatherium. robustum^ inferior molar.

44. Periptychus rhabdodon, part of posterior foot

45. Coryphodon elcphantopus, right fore foot, one third natural size

46. Coryphodon elephantopus^ right posterior foot .

47. Phenacodus primcevus, right anterior foot, one third natural size,

48. Phenacodm primcevus^ left posterior foot, one third natural size

49. Homo sapiens^ left anterior foot (hand), one third natural size .

50. Homo sapiens., left posterior foot, one third natural size

51. Phenacodus primcevus Cope, skull, one third natural size, from below

52. Simia satyrus, section of skull of adult .....
52a. Simia satyrus, section of skull of young ......

53. Homo sapiens, infant at term . . .....

From Leidy
From Leidy

PAGE

. 217
. 217
. 217
. 219
. 219
. 223
. 223
. 243
. 243
. 243
. 244
. 253
. 254
. 254
. 254
. 254
. 255
. 255
. 256
. 256
. 256
. 256
. 257
. 257
. 257
. 257
. 257
. 258
. 258
. 258
. 258
. 259
. 259
. 260
. 260
. 260
. 268
. 269
. 269
. 270
. 270
. 272
. 272
. 273
. 283
. 283
. 284

LIST OF ILLUSTRATIONS.

XIX

PIG.

54.
55.
56.
57.

58.

59.

60.

61.
62.
63.
64.

65.'

66.

67.

68.

69.

70.

71.

72.

73.

74.

75.

76.

77.

78.

79.

80.

81.

, PAGE

Homo sapiens^ portrait of girl at five years . . . . . . 285

Homo sapiens^ portrait of same at seventeen years 285

Homo sapiens, portrait of Luchatze negro woman ..... 287

Homo sapiens, portrait of Luchatze negro woman 287

Homo sapiens, portrait of Satanta, chief of the Kiowa Indians of Xoith

America 288

An Australian native 291

Eryops megacephabu, a batrachian of the Permian epoch of Texas ; vertebral

column 804

Sleeve of coat, showing folds 305

Bothriolepis canadensis, from above ........ 323

Chelyosoma maclovianiim, a tunicate from Point Barrow, Alaska, from above S23
Stypolovhus whitice, skull and dentition, displaying the tritubercular type of

molars ......

' Deltatherium fundaminis, skull, profile
Oxycena lupina, jaws and teeth .
Procehcrtts julieni, skull. From Filhol
Dinictis cyclops, skull
Smilodon neoffceics, skull
CorypJiodon elephantopus, hind foot above

Aphelops megalodus, hind tarsus and metatarsus, from front and above
Proiohippus sejunctus, posterior foot, front
Po'ehrotherium labiatum, posterior foot, front
Poebrotherium vilsoni, carpus, metacarpus, and end of radius, from^ front
Amhlydonus sinosus, a creodont ; distal end of tibia
Oxycena m,orsitans, a creodont ; distal end of tibia
ArchcBlurus dehilis, an extinct cat ; distal end of tibia,
Nimravus gomphodus, a cat ; femur .
Procamelus occidentalis, part of fore foot
Cosoryx furcatus, part of fore foot
Poebi'oiherium vilsoni, part of fore foot

with astragalus

360
362
365
366
306
367
369
369
370
370
371
375
375
375
375
376
376
376

PART I.

GENERAL EYOLUTIOK

EVOLUTION AND ITS CONSEQUENCES.

The broad theory of evolution includes the theories of devel-
opment of the solar system and its members, as expressed by the
nebular hypothesis ; the theory of development of life by molecu-
lar movements consequent upon certain combinations of non-living
matter ; and, lastly, the theory of development of the species of
animals and plants by descent, the later from the earlier, with
accompanying change of form and character. It attempts noth-
ing less than a history of the process of creation of the universe,
so far as we can behold it ; and is, therefore, an attempt to formu-
late the plans and thoughts of the Author of that universe.
Hence, it is not surprising that it excites the interest of the best
of men, especially as it is one of the results of the efforts of a
class of these, crowning many centuries of labor and thought.

The object of the present essay is to discuss familiarly the
latter of these theories of evolution, viz., that respecting the
si3ecies of animals and plants. As all are aware, this mode of
accounting for the creation of organized beings has attained
especial prominence at the present time, and possesses more of
interest to most readers because of its explanation of our own
origin. Moreover, it rests on more indubitable evidence than the
two other theories. The constitution and arrangement of the
members of the solar system point to their origin by derivation
from primal masses of vaporous matter through the mutual opera-
tion of the ordinary laws of attraction and motion. The position-
ing is precisely as it should be had such process taken place, but
the process itself, that is, the change from type to type of celes-
tial body, has not been observed.
I

D. H. HILL LIBRARY
North Carolina State Colteg«

2 GENERAL EVOLUTION.

The case is far diCerent with the theory as regards organized
or living beings. Not only are the mutual relations of animals
and plants to each other such as should have resulted from a de-
scent or development, but the changes from type to type have
been actually observed, and in sufficient number to place the
hypothesis on the basis of ascertained fact, as referring to a cer-
tain range of objects — say, in the case of the animal kingdom, to
individuals distinguished by structural characters within the range
of each of the three to six great primary divisions or " branches."

There are two totally distinct propositions involved in this
question, which are confounded by the general public, and not
unfrequently by students and writers on it. These are, first, the
evidence which seems to prove that this evolution has taken place ;
secondly, the evidence as to the nature of the laws of its progress.
A want of constant distinction between these views of the case
has greatly obscured it and injured the evidence on one side or
the other.

The evidence in favor of evolution is abundant, and is cited
in fragments by various contemporary writers, foremost among
whom, both in time and abundance of writings, comes Charles
Darwin.

Much less has been done in explanation of the laws of evo-
lution. Darwin and his immediate followers have brought out
the law of ^^ natural selection"; Spencer has endeavored to ex-
press them in terms of force; while Hyatt, Cope, Packard, and
others have advanced the law of "acceleration and retardation."

In earlier days, when information was distributed slowly and
books were few, it was long before any new truth or doctrine
reached the majority of people, still less was adopted by the rul-
ing classes. But the modern theory of evolution has been sjDread
everywhere with unexamjoled rapidity, thanks to our means of
printing and transportation. It has met with remarkably rapid
acceptance by those best qualified to judge of its merits, viz., the
zoologists and botanists, while probably a majority of the public,
in this region at least, profess to reject it. This inconsistency is
due to two principal causes. In the first place, Darwin's demon-
stration contained in the " Origin of Species " extends little fur-
ther than as stated in the title of his work. He proves little more
than that species of the same genus or other restricted groups
have had a common origin ; and, further, his theory of natural
selection is to the plainest understanding incomplete as an ex-

EVOLUTION" AND ITS CON-SEQUENCES. 3

planation of their ''origin/' as its author indeed freely allows.
Besides, the unscientific world is particularly unreasonable on
one point. Little knowing the slow steps and laborious effort by
which any general truth is reached, they find in incompleteness
ground of condemnation of the whole. Science is glad if she can
prove that the earth stands on an elephant, and gladder if she can
demonstrate that the elephant stands on a turtle ; but, if she can
not show the support of the turtle, she is not discouraged, but
labors patiently, trusting that the future of discovery will justify
the experience of the past.

If, then, some of the people find Mr. Darwin's argument in-
complete, or in some points weak, it may be answered, so do the
student classes, who, nevertheless, believe it. This is largely be-
cause Darwin's facts and thoughts repeat a vast multiplicity of
experiences of every student, which are of as much significance
as those cited by him, and which only required a courageous
officer to marshal them into line, a mighty host, conquering and
to conquer. These will slowly find their way into print, some in
one country and some in another.

I. THE FACT OF EVOLUTION".

As to the truth of the theory, the proof has been stated in
more than one form. The first and simplest, and essentially the
central argument of Darwin, is as follows :

In every family or larger group of animals and plants there
exists one or more genera in which the species present an aggre-
gation of specific intensity of form ; that is, that species become
more and more closely related, and finally varieties of single spe-
cies have to be admitted for the sake of obtaining a systematic
definition or '' diagnosis," which will apply to all the individuals.
These varieties are frequently as well marked as the nearly-related
species, so far as amount of difference is concerned, the distinc-
tion between the two cases being that in the varieties there is a
gradation from one to the other ; in the species, none. Neverthe-
less, between some of the varieties transitions mav be of rare oc-
currence, and in the case of the ''species" an intermediate indi-
vidual or two may occasionally be found. Thus it is that differ-
ences, called varietal and specific, are distinguished by degree
only, and not in kind, and are, therefore, the results of the opera-
tion of uniform laws. Yet, according to the old theory, the varie-
ties have a common origin, and the species an independent one !

4 GENERAL EVOLUTION.

To find examples of what is asserted, it is only necessary to refer
to the diagnostic tables and keys of the best and most honest
zoologists and botanists. It is true that these diagnoses are dry
reading to the non-professional, yet they embrace nearly all that is
of value in this part of biological science, and must be mastered in
some department before the student is in possession of the means
of forming an opinion. The neglect to do this explains why it is
that, after all that has been written and said about protean spe-
cies, etc., the subject should be so little understood.

It is true that in but few of these cases have the varieties been
seen to be bred from common parents, a circumstance entirely
owing to the difficulties of observation. The reasoning derived
from the relations of differences appears to be conclusive as to
their common origin, unless we are prepared to adopt the oppo-
site view, that the varieties have originated separately. As these
avowedly grade into individual variations, we must at once be led
to believe that individuals have been created independently — a
manifest absurdity.

But variations in the same brood have been found among wild
animals ; for example, both the red and gray varieties of the little
horned owl (Scops asio) have been taken from the same nest.

As further examples of gradation between species and variety,
found in nature, I only have to select those genera most numerous
in species, and best studied. Among birds, Corvus, Emp)idonax,
JButeo, Falco, etc. Eep tiles, Eutaeiiia, Anolis, Lyoodon, Naja,
Caudisona^ Elaps, Oxyhrropus, etc. Batrachia, Rana, Hyla,
Clioropliilus^ Borhorocoetes, AmUy stoma, Spelerpes, etc. Fishes,
PtycliostomuSf Plecostomus, Amiurus, Sal mo , Pcrca, and many
others.

In all these groups of species, or '^genera," it is impossible in
some cases to determine what is variety and what species. This
is notoriously the case with the salmon and trout (Sahno), for one
of the greatest opponents of close division of species. Dr. Giinther,
of London, thought himself necessitated, a very few years ago, to
name and describe half a dozen new species of trout from the
lakes of the British Islands, and, from being a stanch supporter
of the old view of distinct creations, was completely converted to
evolutionism.

Such is one of the views which has forced conviction on the
minds of thoroughly honest men who were not only desirous of
knowing the truth, but were in many cases brought over from a

EVOLUTION AND ITS CONSEQUENCES. 5

position of strong opposition. But the earnest objector says, you
have not after all shown me any real transitions from species to
species ; until that is done your development is but a supposition.

The all-sufficient answer to this statement is to be found in
the imperfection of our system of classification. Thus, if we first
assume, with the anti-developmentalist, that varieties have a com-
mon parentage, and species distinct ones, when intermediate forms
connecting so-called species are discovered, we must confess our-
selves in error, and admit that the forms supposed to have had
a different origin really had a common one. Such intermediate
forms really establish the connection between species, but the
question is begged at once by asserting unity of species, and,
therefore, of origin, so soon as the intermediate form is found ;
for, as before observed, it is not degree, but constancy of distinc-
tion, which establishes the species of the zoological systems.
Transitions between species are constantly discovered in existing
animals ; when numerous in individuals, the more diverse forms
are regarded as *^ aberrant"; when few, the extremes become
*^ varieties," and it is only necessary to destroy the annectant
forms altogether to leave two or more species. As the whole of a
variable species generally has wide geographical range, the vari-
eties coinciding with sub-areas, the submergence, or other change
in the intervening surface, would destroy connecting forms, and
naturally produce the isolated species.

Formerly naturalists sometimes did this in their studies. A
zoologist known to fame once pointed out to me some trouble-
some specimens which set his attempts at definition of certain
species at defiance. *' These," said he, ''are the kind that I
throw out of the window." Naturalists having abandoned throw-
ing puzzling forms out of the window, the result of more honest
study is a belief in evolution by nine tenths of them.

But, says the inquirer again, your variations and transitions
are but a drop in the ocean of well-disting-uished species, classes,
etc. The permanent distinction of species is matter of every-day
observation ; your examples of changes are few and far between,
and utterly insufficient for your purpose.

It is true that the cases of transition, intermediate forms, or
diversity in the brood, observed and cited by naturalists in proof of
evolution, are few compared with the number of well-defined, iso-
lated species, genera, etc., known ; though far more numerous
than the book-student of natural history is apt to discover. But

6 GENERAL EVOLUTION

although the origin of most species by descent has not been ob-
served, every one knows the worthlessness of argument based on a
negative. Unless these cases exhibit opposing evidence of a posi-
tive character, they are absolutely silent witnesses.

He who cites them against evolution commits the error of the
native of the Green Isle who testified at a murder trial. '^ Al-
though the i^rosecuting attorney brought three witnesses to swear
positively that they saw the murder committed, I could produce
thirty who swore they did not see it done ! "

By the inductive process of reasoning we transfer the unknown
to the known, for it is the key of knowledge. It rests upon the
invariability of Nature's operations under identical circumstances,
and for its application merely demands that analysis and com-
parison shall fix that the nature of that of which something is
unknown is identical with that of which the same thing is
known. We then with certainty refer that which is known as
an attribute of that object of which the same quality had been
previously unknown. The following form exhibits its applica-
tion to the question of evolution. As preliminary facts it may
be assumed that :

1. Many species are composed of identical elemental parts
which present minor differences.

2. Some of these differences have been seen to originate spon-
taneously from parents which did not possess them, or, what is the
same thing, are known to exist in individuals whose parentage is
identical with others which do not possess them.

3. The gradation of differences of the same elemental parts is
one of degree only, and not of kind.

4. Induction. — Therefore all such differences have originated
by a modification in growth, or have made their appearance with-
out transmission in descent.

II. THE MAN'NER OE EYOLUTIOK.

In discussing this point, new evidence in favor of develop-
ment must be produced, and some statements of the history of
the opinion made.

The laws which are expressed by all that we find of structure
in animals are four, viz. :

1. Homology. — This means that animals are composed of cor-
responding parts ; that the variations of an original and fixed
number of elements constitute their only differences. A part

EVOLUTION AND ITS CONSEQUENCES. 7

large in one animal may be small in another, or vice versa ; or
complex in one and simple in another. The analysis of animals
with skeletons or vertebrata has yielded several hundred original
elements, out of which the 28,000 included species are con-
structed. Different this from the inorganic world, which can
only claim about sixty- two elemental substances. The study of
homologies is thus an extended one, and is far from complete at
the present day.

2. Successional Relation. — This expresses the fact that species
naturally arrange themselves into series in consequence of a mathe-
matical order of excess and deficiency in some feature or features.
Thus species with three toes naturally intervene between those
with one and four toes. So with the number of chambers of the
heart, of segments of the body, tlie skeleton, etc. There are
greater series and lesser series, and mistakes are easily made by
taking the one for the other.

3. Parallelism. — This states that while all animals in their
embryonic and later growth pass through a number of stages and
conditions, some traverse more and others traverse fewer stages ;
and that, as the stages are nearly the same for both, those which
accomplish less resemble or are parallel with the young of those
which accomplish more. This is the broad statement, and is
qualified by the details.

4. Teleology. — This is the law of adaptation so much dwelt upon
by the old writers, and admired in its exhibitions by men gener-
ally. It includes the many cases of fitness of a structure for its
special use, and expresses broadly the general adaptations of an
animal to its home and habits.

Of course, these laws must be all laws of evolution, if evolution
be true. And such they are ; but this is far from being perceived
by some students, for some of them were in abeyance or neglect
prior to the stimulus to thought caused by the appearance of the
** Origin of Species."

Forty or fifty years ago Germany had been flooded with the
writings of the ^^physiophilosophs." Oken and Goethe had ob-
tained glimpses of the wonderful " unity in variety " expressed
by the laws of homology. The latter saw vertebrae in the seg-
ments of the skull, and leaves in the floral organs of plants. He
had found the magic wand, and many were the harmonious visions
that delighted the laborious toilers among old bones and dusty
skins ; the patient haruspices saw omens in the intestines of birds

8 GENERAL EVOLUTION.

and snakes, and he whose hours were spent over his lens ceased
to be a mere wonder monger. But fashion is fashion, and always
ends in absurdity and stagnation. The physiophilosophs became
extravagant, and mistook superficial appearances for realities.
They did not dream how misleading some of the resemblances
between different elements, for example, of the skeleton may be,
and for once German students did not analyze exhaustively. Cu-
vier laughed at these seekers for beauty, and confounded the true
and the untrue in one condemnation. But the best men labored
forward ; errors began to be exposed, and soon a reaction set in.
Another extreme followed, and the school of Miiller, at Berlin,
denied the meaning of these resemblances and ceased to see any-
thing but differences. Minute and thorough investigation flour-
ished in their hands, and the modern school of German anatomists
has seen no superiors. So the theory of evolution found Berlin.
The disfavor in which physiophilosophy was held secured to evo-
lution a cold welcome, and it has been for Jena and other univer-
sities to give it its true impetus in Germany.

So it has been with the law of parallelism. Some of the
physiophilosophs declared it, stating that the inferior animals
were merely the repressed conditions of the higher. This view
was taught by some men in high position in France. Their state-
ments were, however, too broad and uncritical. The father of
embryology, von Baer, of Koenigsberg, declared there was ^'heine
Rede^^ of such theory, and Lereboullet stated '* that it is founded
on false and deceptive appearances." Even Professor Agassiz in
our day has asserted that no embryonic animal is ever the same as
the adult of another, though he also once informed the writer that
the embryology of two nearly related species had never been studied
and compared. This was subsequently done by Professor Hyatt,
of Salem, for the nautilus and ammonite division of mollusks, and
at about the same time by the writer, for many species of our na-
tive frogs and salamanders, and the result has been a complete
clearing up of the confusion about parallelism, and the clear estab-
lishment of the law.

The results attained are these : The smaller the number of
structural characters which separate the two species when adult,
the more nearly will the less complete of the series be identical
with an incomplete stage of the higher species. As we compare
species which are more and more different, the more necessarily
must we confine the assertion of parallelism to single parts of the

EVOLUTION AND ITS CONSEQUENCES. 9

animals, and less to the whole animal. When we reach species as
far removed as man and a shark, which are separated by the ex-
tent of the series of vertebrated animals, we can only say that the
infant man is identical in its numerous origins of the arteries from
the heart, and in the cartilaginous skeletal tissue, with the class of
sharks, and in but few other respects. But the imjoortauce of this
consideration must be seen from the fact that it is 07i single char-
acters of this hind that the divisions of the zoologist depend.
Hence we can say truly that one order is identical with an incom-
plete stage of another order, though the species of the one may
never at the present time bear the same relation in their entirety
to the species of the other. Still more frequently can we say that
such a genus is the same in character as a stage passed by the next
higher genus ; but when we can say this of species, then their dis-
tinction is almost gone. It will then depend on the opinion of
the naturalist as to whether the repressed characters are perma-
nent or not. Parallelism is then reduced to this definition : that
each separate character of every kind, which we find in a species,
represents a more or less complete stage of the fullest growth of
which the character appears to be capable. In proportion as those
characters in one species are contrasted with those of another by
reason of their number, by so much must we confine our compari-
son to the characters alone, and the divisions they represent ; but
when the contrast is reduced by reason of the fewness of differing
characters, so much the more truly can we say that the one species
is really a suppressed or incomplete form of the other. The denial
of this principle by the authorities cited has been in consequence
of this relation having been assigned to orders and classes, when
the statement should have been confined to single characters ; and
divisions characterized by them. There seems, however, to have
been a want of exercise of the classifying quality or power of *^ ab-
straction " of the mind on the part of the objectors. This faculty
seems to be by no means so common as one would expect, judging
from the systematic ideas of many.

To explain by a few examples selected at random : First, of
species characters, I may cite the fact that all deer are spotted
when young, and that some of the species of eastern and southern
Asia retain the spotted coloration throughout life. All salaman-
ders are uniform, often olive during a larval stage ; some species,
and some individuals of other species, retain the color in maturity.
To take a genus character : all the deer in the second year develop

10 GENERAL EVOLUTION.

their first horn, which is unbranched and small, or a " spike." A
genus of deer inhabiting South America never develops anything
else. To take a character of higher grade : the exogenous plants
usually present net- veined leaves, but the first pair, or those of
the plumule, are of much simpler structure, being often parallel-
veined ; for example, the cucumbers and squashes. Now, the en-
dogens usually produce nothing else than parallel-veined leaves, and
no case is known where a plant bearing this type of leaf exhibits
the net-veined type as its earliest growth.

But what do these facts mean ? As in growth the genus char-
acters usually appear last, I will suppose a case where one genus
represents truly, or is identical with, the incomj^lete stage of an-
other one.

In A we have four species whose growth attains a given point,
a certain number of stages having been passed prior to its termi-

nation, or maturity. In B we have an-

A other series of four (the number a mat-
ter of no importance), which, during the
period of growth, can not be distin-
guished by any common, i. e., generic
character, from the individuals of group
A, but whose growth has only attained
to a point short of that reached by those
of group A at maturity. Here we have a parallelism, but no true
evidence of descent. But if we now find a set of individuals be-
longing to one species (or, still better, the individuals of a single
brood), and therefore held to have had a common origin or parent-
age, which present differences among themselves of the character
in question, we have gained a point. We know in this case that
the individuals, a, have attained to the completeness of character
presented by group A, while others, Z>, of the same parentage have
only attained to the structure of those of group B. It is perfectly
obvious that the individuals of the first part of the family have
grown further, and, therefore, in one sense faster, than those of
group b. If the parents were like the individuals of the more
completely grown, then the offspring which did not attain that
completeness may be said to have been retarded in their devel-
opment. If, on the other hand, the parents were like those less
fully grown, then the offspring which have added something
have been accelerated in their development. I claim that a con-
sideration of the uniformity of nature's processes, or inductive

EVOLUTION AND ITS CONSEQUENCES. H

reasouiug, requires me to believe that the groups of species, that
is, groups A and B, are also derived from commou parents, and
the more advanced have been accelerated or the less advanced re-
tarded, as the case may have been with regard to the parents.

This is not an imaginary case, but a true representation of
many cases which have come under notice. I can not repeat
them here, but refer to the original memoirs, where they may be
found. *

This is a simple statement of the law of '^ acceleration and re-
tardation " of some American naturalists, which probably expresses
better than any other the ^^ manner of evolution," the proposition
with which we started.

Hyatt thus defines it as seen in a group of ammonites which
he studied : " The young of higher species are thus constantly
accelerating their development, and reducing to a more and more
embryonic condition the stages of growth corresponding to the
adult periods of preceding or lower species." f

This form of demonstration of evolution is of far wider appli-
cation than that which I first brought forward. X Iii the latter
case the induction may be limited to a certain range of variation,
but the present law is as extensive as the organic world ; that is,
the ^^positioning" essential to it is found everywhere, from the
lowest to the highest, and in characters from the least to the
greatest in import.

Let an application be made to the origin of tlie human species.
It is scarcely necessary to point out at the start the fact, univer-
sally admitted by anatomists, that man and monkeys belong to
the same order of Mammalia, and differ in those minor charac-
ters, generally used to define a '* family" in zoology.

Now, these differences are as follows : In man we have the
large head with prominent forehead and short jaws ; short canine
teeth without interruption behind (above) ; short arms, and thumb

* See " Odgin of Genera, and Method of Creation," Naturalists' Agency, Salem,
Massachusetts ; or McCalla & Stavely, 237 Dock Street, Philadelphia.

f " On the Parallelism between Stages in the Individual and those in the Group
of the Tetrabranchiata." " Boston Society of Natural History," 4to, 1866, p. 203.

:j: It is quite misunderstood by Darwin, as will be sufficiently evident from the
following quotation from the last edition of his " Origin of Species," 1872, p. 149:
" There is another possible mode of transition, namely, through the acceleration or
retardation of the period of reproduction. This has lately been insisted on by
Prof. Cope and others in the United States." This has only been dwelt on as
accounting for a very minor grade of differences seen in race and sex.

12 GENEEAL EVOLUTIOif.

of hind foot not opposable. In monkeys we have the reverse of
all these characters. But what do we see in young monkeys ? A
head and brain as large relatively to the body as in man ; a facial
angle quite as large as in many men, with jaws not more promi-
nent than in some races ; the arms not longer than in the long-armed
races of men, that is, a little beyond half way along the femur.
These observations are made on a half-grown Cetus apella, from
Brazil, a member of a group more remote from men than are the
Old World apes, yet with an unusually large facial angle. At
this age of the individual the distinctive characters are therefore
those of homo, with the exception of the opposable thumb of the
hind foot, and the longer canine tooth ; nevertheless, the canine
tooth is shorter in the young than in the adult.

Now, in the light of various cases observed, where members of
the same sj^ecies or brood are found at adult age to differ in the
number of immature characters they possess, we may conclude
that man originated in the following way : that is, by a delay or
retardation in growth of the body and fore limbs as compared with
the head ; retardation of the jaws as compared with the brain
case, and retardation in the protrusion of the canine teeth. The
precise process as regards the hinder thumb remains obscure, but
it is probably a very simple matter. The projDortions of the
young Cehus apella enable it to walk on the hind limbs with great
facility, and it does so much more frequently than an adult G.
capiicinus with which it is confined.*

The *' retardation" in the growth of the jaws still progresses.
Some of our dentists have observed that the last (3d) molar teeth
(wisdom teeth) are in natives of the United States very liable to
imperfect growth or suppression, and to a degree entirely unknown
among savage or even many civilized races. The same suppres-
sion has been observed in the outer pair of superior incisors.
This is not only owing to a reduction in the size of the arches of
the jaws, but to successively prolonged delay in the appearance of
the teeth. In the same way men, and the man-like apes, have
fewer teeth than the lower monkeys, and these again fewer than
the ordinary Mammalia, and this reduction has proceeded in rela-
tion to an enlargement of the upper part of the head and of the
brain.

The cause of development may be next considered, and under

* The same relations of man to the anthropoid apes have been dwelt upon by
Prof. C. Yogt.

EVOLUTION AND ITS CONSEQUENCES. 13

this head may be discussed the natural selection of Wallace and
Darwin and other propositions of similar import.

'^ Retardation " continued terminates in extinction. Examples
of this result are common ; among the best known are those of
the atrophy of the organs of sight in animals inhabiting caves. It
is asserted that the young of both the blind crawfish {Orcoiiedes
pellucidus) and the lesser blind fish [TyphlicMliys suhterraneus)
of the Mammoth Cave possess eyes. If these statements be accu-
rate, we have here an example of what is known to occur else-
where, for instance, in the whalebone whales. In a foetal stage
these animals i30ssess rudimental teeth like those of many other
Cetacea when adult, which are subsequently absorbed. So also
with the foetal ox ; the upper incisor teeth appear in a rudimental
condition, but are very early removed. The disappearance of the
eyes is regarded by Dr. Packard, with reason, as evidence of the
descent of the blind forms from those with visual organs. I would
suggest that the process of reduction illustrates the law of *^ re-
tardation " accompanied by another phenomenon. Where charac-
ters which appear latest in embryonic history are lost, we have
simple retardation, that is, the animal in successive generations
fails to grow up to the highest point of completion, falling farther
and farther back, thus presenting an increasingly slower growth
in the special direction in question. Where, as in the presence of
eyes, we have a character early assumed in embryonic life, retarda-
tion presents a somewliat different phase. Each successive genera-
tion, it is true, fails to come up to the completeness of its prede-
cessor at maturity, and thus exhibits ^^retardation," but this
process of reduction of rate of growth is followed by its termina-
tion in the part long before growth has ceased in other organs.
This is an exaggeration of retardation, and means the early termi-
nation of the process of force-conversion, which has been previ-
ously diminishing steadily in activity.

Thus the eyes of the Orconectes probably exhibited for a time
at maturity the incomplete character now found in the young, a
retarded growth continuing to adult age, before the termination
of growth was withdrawn by degrees to earlier stages. With this
early termination of growth came the phase of atrophy, the in-
complete organ being removed and its materials transferred to
other parts through the greater activity of '' growth-force." Thus,
for the reduction of organs, we have ''retardation " ; but for their
extinction, ''retardation and atrophy."

14 GENERAL EYOLUTIOK

III. OIT THE CAUSES OF EYOLUTIOIS'.

1. Inductive Reasoning,

In the present investigation we are endeavoring to discover
new principles, not to apply old ones. The work is similar to
that which occupied Newton in his investigation of the law of
attraction or gravitation. The process by which we arrive at
general truths rests on the consideration of a sufficient number
of observed facts, and the determined qualities which are common
to all we regard as a law. This process requires for its proper
conduct a careful analysis and discrimination of the nature of the
objects considered ; otherwise fallacy will result. As exact analy-
sis is not always observed by the average mind, this inductive
reasoning is not always successfully employed by it, nor under-
stood when presented by others. In the deductive process it is
more at home. With an ascertained principle given, as some-
thing like a staff for the mind to lean on, its application is not so
difficult ; but to such a mind induction presents an appearance
of uncertainty and even of confusion, and these will certainly
exist until order is evoked by the first step — classification. The
theory of evolution has thus been charged with confusion, as
though it asserted that which overtiirew the order of nature. But
the confusion only exists in the mind of such critics. The order
of the creation is one of the foundation facts, and thus enters
the inductive argument as one of its elements. That conclu-
sion which is consistent with this order can not be regarded as its
enemy.

- 2. On Natural Selection.

In endeavoring to assign a cause for the existence of the pecul-
iar structures which define the divisions among animals, Messrs.
Wallace and Darwin have proposed the now well-known law of
natural selection. This states, that, inasmuch as slight variations
appear continually in all species, it is evident that some will be
more beneficial to the animal than others, in its exertions to sup-
ply itself with food, protect itself from enemies, the weather, etc.
It then asserts that those whose peculiarities are beneficial will
excel those less favored, in the successful use of their jDowers, and
hence will live better, grow better, and increase more rapidly.
That by the force of numbers, if not by direct conflict, they will
ultimately supersede the weaker and destroy or drive them away.

EVOLUTION AND ITS CONSEQUENCES. 15

Then, as there are many fields of action and possibilities of ob-
taining support in the world, that the weaker will first be driven
to adopt such of these as their peculiarities may adapt them for,
or not exclude them from. Thus all the positions in the world's
economy are filled and the surplus destroyed. This is styled by
Spencer the ''^survival of the fittest" ; an expression both com-
prehensive and exact.

This doctrine is no doubt a true one, and has regulated the
preservation of the variations of species, and assigned them their
locations in the economy of nature. It was natural that this great
law should have been brought out by such men as Darwin and
"Wallace, who are by nature much more of observers of life in the
field, or out-door physiologists, than they are (or were) anatomists
and embryologists. Their writings in their chosen field of the
mutual relations of living beings in their search and struggle for
means of existence are admirable, and almost unique, especially
some of those of Darwin.

It is to be observed, however, that they both (especially Dar-
win) start with the variations observed. This is assumed at the
outset, and necessarily so, for ^^ selection" requires alternatives,
and these are the product of variation. Great obscurity has arisen
from the supposition that natural selection can originate anything,
and the obscurity has not been lessened by the assertion often made
that these variations are due to inheritance ! What is inheritance
but repetition of characters possessed by some (no matter what)
ancestor; and if so, where did that ancestor obtain the peculiarity?
The origin of variation is thus only thrown upon an earlier period.

Another reason why natural selection fails to account for the
structures of many organic beings is the fact that in expressing
" the survival of the fittest " it requires that the structures pre-
served should be especially useful to their possessors. Now, per-
haps half of all the peculiarities of the parts of animals (and
probably of plants) are of no use to their possessors, or not more
useful to them than many other existing structures would have
been. It fails to account for many characters which express the
relations of homology and parallelism, and is almost confined in
its exhibitions to features which express teleology. This objection
has been insisted on by Kolliker, the writer, and by Mivart ; and
now Huxley, while defending Darwinism proper against the last-
named author, says that *'what the hypothesis of evolution wants
is a good theory of variation.^^

16 GENERAL EVOLUTION".

Plainly enough, tlien, nothing ever originated by natural se-
lection, and as the present essay relates to the origin of types, lit-
tle space can be given to its discussion ; for natural selection,
important though it be, is but half the question, and indeed the
lesser half. It is to the great causa,tive forces as are the gutters
and channels which conduct the water in comi^arison with the
pump and the man who pumps it.

3. On Teleology.

Two classes of structures have been alluded to : those which
are useful to an animal, and those which are not useful ; or the
adaptive and non-adaptive. Nothing is better known than that
animals are well adapted to their situations in the w^orld, and for
their needs as to sujDplying themselves with food, etc. Some part
of every species is so constructed as to enable it to live under con-
ditions where most other kinds of animals would perish. Thus
the sea-rangers, among birds, as the great albatross, etc., possess
long and pointed wings ; while those that live in thickets or
under cover have short, round ones, as grouse, woodcock, etc.
Even our sparrows — those that love the bushes and swamps, as
the song-sparrow {Melosjnza melodia) — have short, rounded wings,
while those that haunt trees have them sharper and pointed, as
the chipping and tree sparrow {Spizella socialis, pusilla, etc.).
Water-frogs have their feet webbed ; land-frogs have small or no
webs ; while tree-toads possess sucker-like expansions of the ends
of the toes, which secrete a glutinous fluid, by which they adhere
to the trunks and leaves of trees. Finally, frogs that burrow have
one or more of the bones of the base of the hind foot {tarsus)
modified into a projecting blade, like that of a shovel ; and, as they
squat down, they literally sit into the ground, and are soon out
of sight in the hole which they dig with these busy trowels.

Cave insects have long and delicate antennae and limbs, ex-
ceeding those of their out-door relations by much. Moreover,
their usual lack of eyes is a clear case of the reverse of adaptation,
i. e., the absence of an organ where not needed.

Less attention has been directed to the non-adaptive charac-
ters, yet they are as numerous as the adaptive. I do not include
under this head useless organs or parts only, but also those which
are useful, but whose peculiarities do not relate to that use as
advantageous to it.

Notable examples of this kind are to be found in the characters

EVOLUTION" AND ITS CONSEQUENCES. 17

which distinguish all of the higher groups of animals and of plants
among themselves. It is easier to ask than to answer what advan-
tages the mammalian skeleton possesses over the reptilian that it
should have superseded it. What end was served by aborting
the coracoid bone, which in reptiles supports the shoulder-joint
from behind, answering to the ischium of the pelvis ? I do not
know how to answer this question on a teleological basis, although
it involves one of the principal characters of the class of reptiles.
What mechanical end was gained by withdrawing the rib-bones
of two cranial segments into the cavity of the ear, to become the
hammer, anvil, and stirrup of the organ of hearing ? * Was it to
perfect the auditory faculty ? Scarcely ; for birds possess as re-
fined and as musical an ear as any mammals, and appear to be
superior to them in discriminating power, yet in them the ham-
mer is the basal element of the lower jaw, and the anvil supports
it, being entirely outside the cranial walls. See again one ground
of distinction between reptiles and batrachians. The base of the
brain-case in the former consists of an axis of bony segments de-
veloped in the primordial cartilage, while in the batrachian it is a
single bony plate, formed by deposit in the membrane which origi-
nally bounded this cartilage. Who can assign any advantage of the
one type above the other which can be looked upon as in any way
related to the external needs of the animals of those classes ?

Another example may be found in the ankle-joints of reptiles,
birds, and mammals. In the first two the hinge is between the
first and second series of tarsal bones ; in the mammals, between
the bones of the lower leg and the first row of tarsal bones. Some-
thing besides the superior mechanical advantages of the latter has
given it predominance over the former.

To turn to the nautilus and ammonite types of Mollusca, we
observe beautiful illustrations of all the laws already stated. As
is well known, these shells have their tubular cavity divided by
transverse partitions. In the nautilus these unite with the outer
wall by a plain angle, but in various genera which lead toward the
ammonites this margin becomes complicated. This results from
an excessive growth of the peripheral part of the partition or sep-
tum, so that in order to confine it to the same space of contact it
must be folded. This plication takes place in a symmetrical man-
ner. The folded edge in Aturia forms a tongue-like loop on each

* The homologies here expressed have been rendered improbable by late investi-
gation. The argument is, however, not affected.
2

18 GENERAL EVOLUTION".

side, on the outer surface. In Goniatites a fold is added on the
back. In successive genera other main folds are added, the last
appearing nearest the center of the coil. These then become
complicated by subordinate undulations which in the more com-
plex forms become the axes of a double row of new lobes and folds,
the whole presenting symmetrical lobate outlines of much com-
plexity and beauty.

But another series of changes accompanies those of the septa,
and are entirely independent of them. These relate to the yari-
ous degrees of winding of the shell. The early form with simple
septa (Orthoceras) was straight, but others which succeeded began
to turn their shell-making round an axis, thus commencing a par-
tial coil. In some the coil was very open ; in others it began
close, and then ceased, the shell finishing straight. Others after
such a course began to wind again, while some made a single turn
near the middle. The most remote from -the starting-point [A^n-
monites, sp.) made a tight and complete flat coil, while some,
whose septa remained simple, did the same (JVautilus).

The direct uses of these various forms of septum and coil are
simply inexplicable, and that one of them was any *^ fitter" to
*^ survive" than another, by virtue of its usefulness, is for me
more than doubtful.

I am tempted to continue this theme, for it might be pro-
longed indefinitely by any one familiar with the details of ana-
tomical structure, but I will only repeat that the illustrations
would be drawn chiefly from the characters of the classes, orders,
families, and other higher groups.

It is not difficult to believe, in the case of the useful structures
first cited, that the law of natural selection has had much, prob-
ably everything, to do with the preservation of tbe animals pos-
sessing them in the various localities to which they are adapted.
But that it has had opportunity to direct the lines of progress in
the second series is not likely. That it had nothing to do with
the origin of either, is certain.

4. On Groivtli- Force.

Every change by complication of structure is by addition;
every simplification is by subtraction. Every addition is a matter
of growth, which is carried on by a process of nutrition. The in-
quiry respecting the origin of new forms centers itself at once on
the history of growth and the influences affecting it.

EVOLUTION AND ITS CONSEQUENCES. 19

If, as I suppose, these additions, either adaptive or non-adapt-
ive, be produced by an acceleration * of growth, it is evident that
the same immediate cause of that increase must be potent in both
cases. That one of the *^ forces" is concerned in growth as well
as in all the active animal and vegetable processes, is obvious to
those who have carefully observed it. The fact that growth, like
work, requires food for its progress and continuance, is reason
enough for suspecting the existence of a force, and in some cases
the relation between this force and other known forces may be
measured.

Prof. Henry pointed out these facts many years ago, and
illustrated them by observations on the growth of the potato and
of the Qgg. The starch of the former, a complex ''organic"
chemical compound, weighs much more than the young shoot
of cellulose, etc., into which it is converted by the process of
growth, so that a portion of the substance of the tuber has evi-
dently escaped in some other direction. This was found to be
carbonic-acid gas and water, derived from the slow combustion of
the starch, which, in thus ''running down " from the complex or-
ganic state, to the more simple inorganic compounds, evolves an
amount of force precisely equal in amount to the chemical force
(chemism) requisite to bind together the elements in the new and
complex substance cellulose, f

It is well known that substances differ in their capacities for
giving out different kinds of force. This, of course, means their
capacity for converting one kind of force into another. Thus, if
glass be rubbed with silk, the motion is converted into electricity,
"while, if it be rubbed by the hand, heat is the principal result.
In some cases chemical force, set free by decomposition, is con-
verted into light ; in others, heat ; in others, to electricity, often-
er to several at once. But one substance, so far as known, pos-
sesses the power of converting this chemical force or heat into
growth-activity, and that is the material out of which the living
parts of animals and plants are composed. This is a protein, a
compound of carbon, oxygen, and nitrogen in the order of rela-
tive quantity, with a smaller proportion of hydrogen, the whole
being often associated with still smaller quantities of sulphur

* For the definition of this term see first article, in May number of '* Penn
Monthly." (Antea, p. 11.)

f "Agricultural Report of Patent Office," 185*7.

20 GENEKAL EYOLUTIOK

and phosplionis. In its mechanical aspect, as the material out
of which structures and tissues are made, it is called protoplasm.

This substance exhibits two different phenomena of force-
energy, viz., motion and growth. Motion is exhibited by con-
traction and expansion, but which is the active state and which
the passive state is matter of question. Some physiologists regard
*^ contractility " as the energetic state. Kadcliffe believes that
extension is the energetic condition, and contraction a rebound
or discharge of the extending force. He finds dead protoplasm
to be a dielectric, and believes that in life each muscular fibrilla
acts like a Ley den jar. It has been demonstrated that the outer
layer of the sheath of a muscular fibrilla is positively electrified in
life, while the cut extremities are negative, and it is shown by
Eadcliffe that the inner side of the sheath becomes negatively
electrified by induction. The attraction of the opposite electrici-
ties on opposite sides of the sheath compresses and elongates it,
thus, according to his theory, producing muscular extension. The
nervous cells and tubes he believes to act in the same way ; the
difference being that the walls and sheaths are in a state which
prevents compression and extension. The phenomena of mus-
cular extension and nervous tension he believes to be terminated
by a discharge of the force, such as takes place in electrical fishes,
but in much smaller quantity. Thus motive force resides as a
form of electricity in protoplasm, and in highly organized animals
is specialized into neurism.

As to growth-force, all its exhibitions may be reduced to cell-
division, cell-nutrition, and cell-origin. Cell-division exhibits
two prominent varieties. In both the cell nucleus first divides ;
in the ordinary mode, the cell-wall contracts at opposite points,
forming approaching plications, which, when they meet, divide
the cell. In the other mode or proliferation, the divisions of the
nuclei approach the cell-walls, which bulge opposite to them,
forming diverticula, which isolate themselves by opposing con-
tractions at the base, which meet as before. The nature of the
force thus displayed is as yet only speculative, and its demonstra-
tion will result largely from observation on cell-origin from homo-
geneous protoplasm. Eadcliffe suggests an ingenious theory.
He supposes that the protoplasm acquires an external layer differ-
entiated from the internal mass by exposure to and contact with
external substances, and that the electricity generated in the in-
terior is distributed on the under surface of this stratum. That

EVOLUTIOI:^ AND ITS CONSEQUENCES. 21

this induces opposite electricity on the external surface, which, as
in the muscular cell, causes compression, and therefore extension
of the stratum. This extends itself beyond its contents, which
may be attenuated, filling the space, or contracting, forms the
nucleus.

This view will not, however, account for nucleus and cell-
division, which are the subsequent and principal exhibitions of
growth-force. Perhaps the following suggestions may throw some
light on it. Should a polar tendency appear in the nucleus, were
the protoplasm of the proper viscidity, the poles being of like
electric name, would tend to separate by repulsion, thus forming
the hour-glass shape so well known, and afterward division.
This nucleus division would inevitably be followed by division
of the cell-wall, if its inner face were electrified in opposition to
the nucleus. For the wall being attracted toward it equally all
round, the separation of the two nuclei would be followed by an
incurvature of the walls opposite the interval between the nuclei,
in order that each should maintain a position equidistant from
its center. Further divergence would result in the completion
of the cell-wall of each, apart from the other. This process
would be supported by nutrition of the cell, which proceeds by
the passage through the cell-wall to the nucleus, of additional
protoplasm from the blood. Of course, the prime question is as
to whether polarity can appear in the nucleus. That growth
is first polar appears probable on consideration of the globular
and discoidal forms of the lower animals, and that this principle
lies at the basis of the growth of the higher is rendered equally
probable by the phenomena of symmetry of different kinds, as
bilateral, anteroposterior, etc. The electricity supplied to the
outer sheaths of muscular fibrillae is, according to Dubois Eey-
mond, positive. That covering the surface of the nucleus must
be thought to be positive also, if it be effected in opposition to the
inner wall of the cell-wall, which is known to be negative by ex-
periment. But in that case it would be difficult to perceive why
it should not fill the cell by attraction to the wall. If, on the
other hand, it be a generator of negative electricity, it would re-
tain its integrity and induce a temporary change in the wall.
The transmission of protoplasm through the cell-wall to the
nucleus would produce an accumulation of electricity to be dis-
charged in extension, or a disturbance of equilibrium, to be fol-
lowed by polarity and division ; but the conditions under which

22 GENERAL EVOLUTION".

these results would appear are, of course, unknown. The me-
chanical arrangement and condition of the parts would have
much to do with it.

We are, however, here in the arcana of life, and the forms of
law which rise before the mental vision are but as the statues of
Memnon that greet the toiler on the river of mysteries ; they loom
upon its banks in twilight, and the w^hen, the how, and the where-
fore remain unanswered. But the river of Africa is yielding her
secrets, and, though the life that she nourishes may be the last she
will give up, it is no less surely promised to the patient inquirer.

A great advance toward an explanation of the operation of this
growth-force was made in the demonstration of the fact that its
highest exhibitions are confined to the multiplication of cells by
division of pre-existent ones, by contraction of their nuclei and
walls in lines which finally meet.

The construction of additional parts consists solely of this cell-
growth, but the character of the result is, of course, dependent on
the position at which this addition takes place. It may be at the
terminus of a limb to add another toe, or on the wall of an artery
to add a valve. It may be in the brain to add a band of fibers,
or on the edge of a muscle to extend its width.

That tissues are made of cells of original or altered shape, sepa-
rate or confluent (flown together) is well known. That the ar-
rangement of tissues into organs is due to the direction of this
multiplication is also true. Thus a gland is a collection of folli-
cles, each of which is a bagging of a plane tissue. This bagging-
is an exaggerated convexity, which is occasioned mechanically by
excess of cell-growth at one spot on a uniform surface. Solid
parts are all formed, in the first insta7ice, of simple segments.
These are parts produced in a straight rod by excessive elongation
or growth ; the process being as before, the division of cells and
distribution of homogeneous protein between them. All this is
derived from the study of homologies combined with embryology,
and the result is wonderful, and simplifies at once our ideas of the
action of the growth-force. It is mainly a repetition of cell-divis-
ion, the result as to structure being entirely dependent on the
influences which locate its activity and regulate its amount.

Now, its amount will depend on the capacity of the existing
organism to convert heat, etc., into it ; and the form, as to tissue,
etc., in which it appears, depends no doubt on the complexity of
the machines or organs of which the organism is composed. In

EVOLUTION AND ITS CONSEQUENCES. 23

the case of the higher organisms we have muscle, converting the
results of nutrition into muscle ; skin and nails making more skin,
etc. ; brain making more brain ; bone making more bone.

The prime question is the cause of the location of growth-
force. Experiments on this point are greatly needed, and in their
absence it will be necessary to take a wide survey of facts.

A given animal Organism can only convert a given amount of
force, and that capacity must remain uniform so long as the
machine or structure remains the same. If, however, an addition
to its work is developed in one quarter, a subtraction from some
other region must take place if the whole amount remain the same.
When, then, a useful organ is added, subtraction from some less
important locality must result, and, as a consequence, the latter
must become still less prominent in the general economy. Hence,
the development of the useful class of organs already cited must
always be accompanied by a corresponding disappearance of use-
less ones. This would be by reduction or retardation. But, in
the case of the complex folds of the margins of the septa in the
ammonite, useless parts are added by acceleration. Here a gradual
increase in the amount of growth-force must be believed in.

The representation of simple growth-force, i. e., the result of
bathmism, not specially located, is seen in general addition to size.
In domestication careful feeding, associated with protection against
all exhausting exposure or exertion, tends to this increase of size.
This is well known to be the case in hogs and cattle and animals
of quiet and easy life. The reverse conditions, as poor food, ex-
posure, and disproportionate exertion, reduce the size ; witness the
Maryland breed of cattle, and the semi-wild hogs of the Southern
States. This matter is, however, nicely balanced with the pro-
duction of motion, for if the latter be excessive, or the supply of
material for consumption be insufiBcient, growth-force must be
evolved in less amount.

It will be necessary here to state that the supply for the con-
version of all the forces of the body is derived from the nutriment
as circulated in the blood.

But the condition of plethora of growth-force is also the one
highly favorable for the appearance of variations of structure, or
the location of growth-force in new places. Domesticated animals
are notorious for this variation, while the still more numerous ex-
amples of *^ protean" species in nature are always predominant
forms, abundant in individuals and widely spread. For example.

24 GENERAL EVOLUTION.

the wolf, the red fox, the red-tailed hawk, the garter-snake, the
tiger, salamander, etc.

That the yariability depends on a peculiar condition of the ani-
mals themselves, and not on domestication, excepting in so far as
it produces these conditions, is plain, not only from the above
facts, but from those observed in domestication. It is well known
that while pigeons, fowls, cattle, dogs, etc., are variable, or '^ pro-
tean," the peafowl (Pavo) has maintained its specific characters
with great accuracy during a period of domestication as long as
that of the other species named. The same may be said of the
guinea {Numida) and the turkey {Meleagris). These facts show
that domestication is only a remote cause of variability.

5. On the Location of Growth-Force.

With the fact of increase of general growth-force before us,
have we any others which can guide us in fixing on a cause for its
special location ? It is plain that the useful additions which have
constituted certain genera, families, orders, etc., what they are,
must have been produced as a consequence of the existence of a
need for them ; or, on the other hand, being created first, they
must have sought for use, and found it. But what are the rela-
tive chances of truth for these two propositions ? In the second
case, admitting evolution as proved (see Part I), we perceive that
an almost infinite chance exists against any usual amount of
variation, as observed, producing a structure which shall be fit to
survive in consequence of its superior adaptation to external cir-
cumstances. It would be incredible that a blind or undirected
variation should not fail in avast majority of instances to produce
a single case of the beautiful adaptation to means and ends which
we see so abundantly around us. The amount of attemjot, failure,
and consequent destruction, would be preposterously large, and
in no wise consistent with the facts of teleology as we behold
them.

What of the opposite view ? We have in its support the well-
known facts of determination of nutritive fluid during use of
parts, not only for supplying fuel for the motions of use, but also
for growth-force and material for the increase in bulk of the part
used. Who has not remarked the large size of the hands of the
laborer, and of the nails of the working-woman ? Who can not
remember some of the countless examj)les of certain modifications
of form being associated with special excellence of use of the parts

EVOLUTION" AND ITS CONSEQUENCES. 25

in different races of the same species of individuals of common
parentage, showing that they must have grown with the history
of those races ? Who does not know the short, wide jaws of the
bull-dog, with their oblique teeth, produced by the expansion of
the zygomata to accommodate the huge temporal muscles so neces-
sary for maintaining a firm hold of its enemy. Then the long and
full nose of the hound, and its more extended turbinate bones —
how closely is this connected with its developed scent ; while the
light muscular forms of the greyhound are undoubtedly necessary
to its well-known speed. If it be said that these variations have
not resulted in a single change of structure worthy of note by a
systematist, we can point to the Japanese dog, where the excessive
reduction of the jaws anteriorly has resulted in a total loss of some
of the premolars and molars. The loss of molar and incisor teeth
from shortening of the jaws, in the human species, has been al-
ready noted. The number of such instances is very great, but, as
space to enumerate them fails, it is only necessary to add that they
are characters of high importance in a systematic sense. Their
importance will be more readily conceded in remembering the
proposition, already stated, that species are simply isolated varie-
ties, and of similar origin.

Confirmatory of this view are the facts already cited with ref-
erence to the relation of motive to growth-force. The force in-
volved in both being seen to be similar, perhaps identical, the
former represents its energetic state as discharge and motion, the
other energetic without discharge, in the growth of cells. And
whatever determines this force to a given part of the body must
then probably result in both of its exhibitions, dependent on the
kind of cells which receive it. As above remarked, the conditions
which determine the result are unknown, except that the two
kinds of muscular cells are the only ones in which elongation is
strongly marked.

Another reason for believing in use as a cause of structural
change is the manner in which the same useful structures have
evidently appeared on totally distinct stems, as an evident adapta-
tion to the same circumstances in which the different types have
been equally placed. Thus the birds of prey possess the hooked,
often toothed, beak, appropriate for tearing and destroying ani-
mals. Their stock is the same as that of the cuckoos and parrots,
and even of the pigeons. The butcher-birds are of the division of
songsters, not widely removed from the thrushes, and far enough

26 GENERAL EVOLUTION.

from the raptores, yet tlie same hook and dentate bill reappears in
them, as adapted to flesh-eating habits.

Among the reptiles, which were no doubt originally land ani-
mals, and derived from batrachians, we haye a large number
adapted to swimming in the ocean, and these not all of the same
stock. Thus the Plesiosauri are crocodilian in relationship, while
the Pythonomorpha of America were of the same that produced
the snake and lizard. Again, the same modification appears in the
Cetaceans, or whale, etc., among mammals which are primarily a
terrestrial division.

It is a nice point of phylogeny (or the science of genealogy) to
ascertain whether adaptive or strictly ^'bathmic" (or embryonic
grade) characters came first in a time in a given group. Among
frogs we have four divisions. One has an embryonic mouth and
embryonic breast-bones ; another, embryonic mouth and complete
breast-bones ; the third, embryonic breast - bone but complete
mouth; and the fourth, with both complete. The first is the lowest
and probably the oldest in time ; agreeably to this supposition, it
is distributed over the whole earth. The second is East Indian
and African ; the third and most extensive is Australian and
American ; while the fourth is confined to the Old World and
JSTorth America. The second, third, and fourth divisions possess
corresponding series of genera of different structure adapted to
different modes of life. Some have shovels for burrowing, some
webs for swimming, and some palettes for adhering to branches
and leaves of trees. If these characters were first fixed, then those
with the more perfect breast-bone and mouth are descendants of
those with the less perfect ; if, on the other hand, the conditions
of mouth and breast-bone were first fixed, then each division thus
defined in its special region was modified into the subdivisions,
each adapted to a special mode of life. I have called these parallel
divisions "homologous groups," and probably the origin of the
embryonic modifications has sometimes come first, and sometimes
the adaptive structures have preceded. Nevertheless, the lowest or
most embryonic division will often have developed its own adapt-
ive divisions, and each of these will agree in 'producing descend-
ants which have advanced in the embryonic scale, and so produce
homologous groups.

For these and other reasons it is concluded that the useful
characters, defining natural divisions of animals, have been pro-
duced by the special "location of growth-force" by use. Useless

EVOLUTION AND ITS CONSEQUENCES. 27

ones have been produced by location of growth-force without the
influence of use, or by its subtraction, due to a disturbance of
equilibrium, consequent on the special location elsewhere.

But we go back to the origin of the question in investigating
the action of growth-force undisturbed by the interference of lo-
cating influences. This is only to be ascertained by an examina-
tion of lower organisms in connection with the higher. A point
that first strikes the student of higher animals is, that after he has
proved the law of Jiotnology to be true, as regards different animals
when compared, he further finds that the parts of the same ani-
mal are also homologous, that is, right hand and left, front and
behind, bottom and top are also constructed on the same plan, so
as to be reduced to the same elemental parts. This is described
under the names of "anteroposterior" and ^* bilateral symmetry,"
etc.* These laws apply to all parts of the organism, and, though
there appear to be exceptions, these are traceable to a common
symmetrical type, the change wrought being one form of speciali-
zation. It is not surprising then that the lower we descend in the
scale of life the less marked is the departure from the entirely
symmetrical disposition of parts as regards the common center.
This is beautifully seen in the EacUata, etc., where the jelly-fish,
the star-fish, and the sea-urchin are familiar examples.

But these are complex compared with forms below them. The
minute Polycystina construct shells of beautiful sculpture or
tracery ; but, though they present many forms, they may be all
referred as modifications, to the symmetrically-marked disk. Of
cellular animals, Trichodiscus represents a discoidal aggregate,
and Actinophrys a globular mass of cells. Monas and its allies
consist of one or several cells in globular form.

Lastly, in the first appearance of life in the most complex ani-
mal we have first a cell, which, then '^ segmenting," divides itself
so as to become a globular mass of identical cells, arranged about
the center.

From the cellular animal upward the operation of addition of
parts is then one of repetition, and that centrifugally in the case
of bodies which are developed in all planes, or peripherally in those
which are in one plane.

Thus the complication of the edges of the septa of the am-
monites is accounted for. First, the growing animal was supplied

See Prof. B. Wilder, in Proceed. Boston Society Nat. Hist.

28 GENERAL EVOLUTION.

with an excess of growth-force. The type of the preceding gen-
eration being strictly adhered to according to the laws of inherit-
ance, the only opportunity for its exhibition was necessarily after
the inherited parts were completed by acceleration. The results
could only, therefore, be exhibited on the edges of the new septa
and free margin of the outer wall. As the older growths me-
chanically restrained the new septa from mere extension, folding
or plication must have resulted from the crowding of additional
surface into the small space. This folding would take the form
of simple branching, and then "repetition" of the process by a
refolding of the outlines of the first fold. The edge would thus
have the digitate or pinnately branched appearance it is known to
present.

Another case of folding is that of the brains of the higher
mammals, including man. This was occasioned by excess of
growth-force distributed to the circumference (from an inherited
central region), exceeding in amount that of the space (skull) in
which it was inclosed. Folding was necessary for its accommoda-
tion in the contracted space. This is a highly useful modification.
Another case like that of the ammonite above cited, whose use is
not so readily determined, but which illustrates excess of growth-
force on some other account, is that of cotyledonary leaves in some
plants. In these cases the growth of the leaf is accelerated, re-
quiring plication for its accommodation.

We therefore have the two laws regulating the " location of
growth-force " irrespective of use, viz. : 1, the centripetal or po-
lar tendency ; 2, the peripheral tendency ; both more or less de-
termined by the inherited central or first grown parts.

There is, however, another element which in animals disturbs
the symmetrical direction of growth-force besides use, and which
precedes use, i. e., effort. Use presupposes a part to use, and a
simple part is sufficient for its influence, so that it be usable ; but
the first beginnings of few structures are usable. As Mivart has
objected to natural selection, that the first rudiments of organs
could never be sufficiently important to an animal to give it a
preference in the struggle for existence, so it might be urged
against the theory of use that rudiments are generally useless,
and could not have been originated by use.

The effect of use is, howcA-er, twofold. The contact with ob-
jects used has some effect in stimulating nutrition, as well as the
exertion of the muscles necessary to use. But determination of

EVOLUTION AND ITS CONSEQUENCES. 29

nutritive fluid is well known to be under the influence of nerve-
force. How imagination stimulates secretion is seen in the famil-
iar example of the flow of saliva in anticipation of food ; a very
different example is the phenomenon of blushing under emotional
stimulus. Nevertheless, it is not evident that growth can result
with any such facility in a fully grown animal. It is thought that
the effort becomes incorporated into the metaphysical acquisitions
of the parent, and is inherited with other metaphysical qualities
by the young, which during the period of growth is much more
susceptible to modifying influences and is likely to exhibit struct-
ural change in consequence. Certain it is that acceleration ceases
with growth, and, as the young of animals are not in complete re-
lation with the surrounding world, the influences controlling it
must be inherited. This consideration renders it doubly probable
that the results of effort on the part of the j)arent appear in change
of structure in the offspring.

Of course, immense numbers of cases of continued effort can be
produced by the objector, in which no structural modification has
resulted. There are various reasons why a modification should
not take place. In the first place, the exertion of use must be
great, habitual, and long-continued ; in the next place, abundant
food must be at hand ; finally, growth-force must be to spare in
the growing young, either from some less necessary part or by ex-
cess. Now, cases are probably not rare where none can be spared
from another part without injuring the efficiency or viability of
the animal ; hence, all such changed individuals would perish
through some form of natural selection or disease.

Domesticated animals can be pointed out where effort and use
have long been put forth in the service of man without changing
structure. But such effort is not to be compared for a moment
with that put forth by animals in a wild state, in seeking food or
protection from enemies. The protection furnished by man, and
consequent release from the struggle for existence, has reduced
the chances for such variations greatly. Nevertheless, variations
profitable to man have resulted ; witness the race-horse and carter.

In cases where one side of the body is used in excess of the
other, unsymmetrical development would be counteracted by the
law of polar or centrifugal growth, all that might be acquired by
the one side being inherited by both. Even this original sym-
metry has, however, been overcome in some types, as in the
flounders (in the jaws and teeth as used parts). This part of

30 GENERAL EVOLUTION.

the subject is purely hypothetical, however probable, but the as-
pect of the discussion will be materially brightened to the reader,
if he have previously adopted, with the author, the principle that
evolution has been the mode of origin of the present life-forms of
the earth.

Reverting now to those beings which are either in part or en-
tirely destitute of the power of determining these movements, as
plants, various causes present themselves as modifiers of the polar
or centripetal activity of growth-force. In the case of a plant, the
medium in which it grows modifies the result ; for example, the
downward growing axis or root differs much from the upward
aerial portion or stem. Aquatic plants, supported beneath or on
the surface of the water, lack the strong stems and braces neces-
sary to air-growing plants ; while of the latter, those with weak
stems develop tendrils and other supports. In these cases physical
laws have been the guides of growth-force. In the case of bright
colors, which we know to be impossible in vegetation without sun-
light, the influence is chemical.

The first physical law is, that growth-force, uninfluenced by
inherited peculiarity,* or any stronger influence locating a nutri-
tive fluid, must develop extent in the direction of least resistance,
and density on the side of greatest resistance, when not too great.
The illustration of this statement would be that a globular mass of
cells brought to the point of Junction of two media, as water and
earth or air and earth, elongates in the direction of the medium pre-
senting the least resistance, i. e., air. Thus a longitudinal develop-
ment would originate from a centrifugal, and a repetition of the
same process would produce branches. The reason why repetition
should appear along the sides instead of as continued prolongation
of the axis, arises probably from the difficulty of conveying fluid
nutritive material far from the base as a source of supply, and the
occurrence of various mechanical obstacles easy to be conceived.
In low plants, where nutrition is absorbed by all parts of the axis,
which branch, as the subterranean parts of fungi {myceliwn), dif-
ference of local supply would produce an effect. In higher plants,
where fluid nutriment is only introduced at one point (the root),
and conveyed by special layers of cells or tubes, the difficulty of
maintaining supply at a distance from its source would encourage
lateral repetition or branching, f

* This is supposed to be due to atomic peculiarity of cell-substance.

f The great power exerted in a given direction by growth-force due to gradual

EVOLUTION AND ITS CONSEQUENCES. 31

6. On the Origin of Intelligence,

Leaving this part of the subject, we approach one of higher
interest, viz., the effects of the metaphysical or mental acquire-
ments of animals on their exertions in effort and use. The growth
of the mind in animals has, no doubt, followed the same laws
obeyed by that of man ; the difference being that the lower forms
have remained permanently fixed in stages early passed by the
lord of living beings. The foundation qualities from which all
the phenomena of intellect may be derived are, the powers of re-
tentiveness (memory) and of perceptions of resemblance and dif-
ference. These traits are well known to be possessed by many
animals, and perhaps in some degree by all. Their possession
will be modified by the power of exercising attention, which, in
its turn, will depend on the sensitiveness of the animal to impres-
sions^n other words, the ease with which consciousness may be
aroused.

The origin of the disposition to take food will be the rudiment
of all that appears as ivill in higher animals, and which, though
supposed to guide, is the creature of so many stimuli. This ori-
gin is supposed by metaphysicians to be the result of education
of the '* spontaneous activity" of animals by their pleasures and
pains.

The brain of man and of other animals is an organ which re-
ceives and retains pictures and impressions, both painful and
pleasurable. The retention of these pictures is not a state of con-
sciousness, but they may be brought into the consciousness accord-
ing to the law of "contiguity," or association. That is, that the
recurrence in the actual of some object or event, which was per-
ceived on a former occasion, at or near the same time as another
object or event not again repeated in the actual, will bring the
latter before the consciousness. So, also, the revival of one such
picture will bring within the mental vision others impressed on
the mind at or near the same time as the first. These events may
have been in the reality either painful or pleasurable. On the
recurrence of circumstances which on a former occasion resulted
in pain, the resuscitation of the mental picture, then impressed on

acquisition and inheritance is illustrated by the plantain, Plantago majoy. Although
without axis, it has been observed by James C. Cresson, in the Philadelphia Park,
and Alfred Cope, on his drive, to force itself through a solid bed of hard vulcanite
pavement, several inches in thickness.

32 GENERAL EVOLUTION".

the memory, produces an anticipation of the pain, and the ani-
mal at once flies from the source of danger. So, also, with pleasur-
able objects, the resultant action being the reverse, or an attraction
to the object. In both cases a previous experience of the relation
between the object and the sensation of pleasure or pain must have
been had.

There is^ in addition, the power of determining differences and
likenesses, by which contiguities or associations are originated in
the mind, of a character different from that resulting from the
relations of times of receipt of the impression. Such contiguities
recall pictures to the consciousness in consequence of their resem-
blances in essential qualities.

On these two bases, together with the perceptive faculties, rest
the complex phenomena of the animal and human minds. They
are probably physiological functions of brain tissue, for the follow-
ing reasons, among others :

1. Impressions are conveyed by physical means to the brain.
The brain can only receive a given number at a time without ex-
haustion, and is prepared to receive more after being nourished.
Impressions long forgotten are revived in certain states of disease.
Impressibility and memory are most marked during growth, and
diminish with age.

2. If impressions are physically produced and preserved in the
brain, those made at or near the same time would remain close
together in the brain, and this material proximity would be the
^* contiguity " according to which they would come before the
consciousness.

3. Classification or appreciation of resemblances takes place
unconsciously in the mind (by '' unconscious cerebration "). Re-
semblances not seen at the time of impression suddenly flash into
the consciousness on a subsequent revival of it. The " contigu-
ity " to like things thus established may be more or less lasting in
the mind than the contiguity of circumstances under which the
impression was made.

4. As ^^ contiguity" in time is believed to be revived by
contiguity in location of impressions in the ^^i^erceptive" part
of the brain, so *^ contiguity " of resemblance may be believed to
depend on contiguity of location in the "reflective" part of the
brain.

The retention of the contiguities of time and of resemblance
constitute the basis of education of an animal, and its intelligence

EVOLUTION AND ITS CONSEQUENCES. 33

will be in proportion to the number and comj)lexitjof these ac-
quisitions.

The lowest exhibitions of contiguity, or association in time,
do not require a nervous system for their display. The Protozoa,
which are without nervous system, exhibit its results in their de-
terminate seizure of some small objects as food and rejection of
others. The sea anemones (Actinia) display some preferences as
to the substances to which they attach themselves. All power of
taking food implies the retention of the impression of pleasure on
first accidentally coming in contact with it. This power is then
present in protoplasmic beings of the simplest type.

All the movements of animals have been shown to depend on
a direction of this motive force, consequent on a necessity for
avoiding pain and obtaining pleasure. It may be regarded, more-
over, as a truth that heightened vitality or energetic conversion
of force is always a state of pleasure, while depressed vitality is
generally the cause (as well as a consequence) of pain. Hence the
pleasurable nature of taking food, and the early education of an
animal in the distinction between objects nutritive and non-nutri-
tive.

It is well known, however, that food may be taken, and many
or all other functions and acts be performed automatically, or in
a state of unconsciousness. This is as much the case with the
highest powers of thought (as in unconscious cerebration) as with
the humblest acts which satisfy bodily wants. The question then
arises whether these acts may not arise in a state of unconscious-
ness. So far as our own self-knowledge goes, we would reply in
the negative. All intellectual functions are produced by educa-
tion, and education involves consciousness at every step. Other
habitual and automatic acts were originated consciously, but the
contiguity of parts of the act becoming impressed on the brain,
future repetitions of it are reflex or unconscious. We have seen
that the development of the habits of animals is in strict obedi-
ence to the preference for pleasure and avoidance of pain. Pleas-
ures and pains of course express sensations which involve con-
sciousness. It then appears to me that, in the lowest animal, con-
sciousness must be present at the time of origin of every habit,
but that it may have been soon lost in each case, and the habit
become automatic.

If this position be true, every subsequent addition to or change
of habits must have been accompanied by a resuscitation of con-

34: GENERAL EVOLUTION.

sciousness. But how is consciousness aroused in the cases which
we can investigate — that is, in our own sjoecies ? In the common
case of sleep, a mere sound is sufficient to cause its return. In
syncope and other forms of loss of consciousness, a sudden shock,
as of cold water thrown on the face, will often restore it. In
ordinary states, comjiulsion or pressure will produce a more in-
tense degree of consciousness. Indeed, in many j)ersons conscious-
ness varies greatly under different influences ; thus a dreamy state
naturally follows a lack of nutrition of the brain, as during a fast,
but the mind is readily aroused from it by a strong or sudden im-
pression made on the senses or by an effort of will. It is, hence,
to be believed that in animals whose acts may be largely automatic
consciousness is aroused by exceptional sights, sounds, hunger,
and other sensible impressions, the more readily in proportion to
the development of the sensory ganglia of the brain. In the low-
est animals, consciousness will be aroused with much greater diffi-
culty, and life must be in part a blank, and in part a dream, at
rare intervals illumined by gleams of consciousness produced un-
der the influence of strong external stimulus. At these times of
awakening we must believe that new movements are instituted,
which will become habitual in proportion to the extent to which
they are repeated.

From what is known of reflex actions, it is evident that move-
ments may become habitual, and hence automatic, wherever cellu-
lar or gray nerve-substance exists. Thus, movements instigated by
the spinal nerves derive their automatism from the spinal medul-
la. This axis no doubt derived the original nerve-force from the
brain, but repetition of the act under the original stimulus con-
fers the automatic power on the spinal cord or ganglionic center
as certainly as on the brain. This must of necessity follow the
complication of nervous structures by addition to the original
center. Thus are explained the automatic movements of the
frog's or centipede's legs in the well-known experiments, when
separated from the brain or principal nervous center.

Greater difficulties are experienced in accounting for the origin
of the automatic movements of plants. It is evident, however,
that many of these, perhaps all, are not due to the energy of mo-
tive-force, but are phenomena of growth-force alone. Motion is
produced by the change of direction imparted to growth-force by
the influence of heat, light, contact, etc. This will largely follow
as a consequence of the longer persistence of growth in plants

EVOLUTION AND ITS CONSEQUENCES. 35

than in animals. In some of the yery lowest plants movement
wonl'd seem to be similar to that seen in the lowest animals. The
origin of intelligence is then to be found in the first traces of con-
sciousness. But inquiry will go further in the search for truth.
One school of physiologists believes consciousness to be due to cer-
tain molecular changes of nerve (i. e., brain) substance. No doubt
these are essential to consciousness ; yet it is, at least, utterly
inconceivable that any molecular condition should be capable of
recognizing either pleasure or pain. Here we find the first ap-
pearance of the '^feelings," that part of the human mind which
deserves to be called, par excellence, '*the soul," and which is
the ^Mocator" of all the forces which go to build up the tis-
sues, organs, and parts of the body ; and hence the organic type
of the intellect and even of the will. For if we find growth-force
to be a correlative of physical force, and subject to motive-force
for its *Mocation," so, while we find that motive-force is in like
manner but another equivalent of ordinary force, we find it also
subordinate to this principle which "locates" it.

7. On Intelligent Selection.

We will now retrace our steps along the line of causes and
effects, and see, if possible, the nature and results of "intelligent
selection."

Protoplasm, homogeneous or cellular, discharges a force called
"motive-force," or neurism, which it converts from surrounding
forces by virtue of its molecular (chemical) or atomic constitu-
tion. Its spontaneous exhibitions as movements bring it into
contact with surrounding objects, when, if sufficiently sensitive
to impressions, consciousness of a pleasurable or painful charac-
ter is aroused. Then in proportion to its sensitiveness, and the
strength of the impression, the protoplasm retains the latter in
an unconscious way, and, on the subsequent recurrence of the ob-
ject to the consciousness, the pleasurable or painful attribute is
also revived by the law of "contiguity." The "vital principle"
interfering restrains the motive-force from exercise toward it, if
it be painful, or releases it for motion toward it, if it be pleasur-
able. This quality of the vital principle is a power of choice, and,
in so far as consciously exercised, is will* Nothing is better
known than that acts originated consciously may, by repetition,

* For further development of this subject see Part IV of this book.

36 GENERAL EVOLUTION.

come to be exercised unconsciously, or as habits. The form these
habits take, will depend on the opportunities and conditions
offered, for instance, in the matter of food, by the surrounding
order of things. Motive-force is, of course, only another name
for effort and use ; the former being a putting forth by means of
conducting material or organs, without executive apparatus ; the
latter always requiring organs or parts by which to execute.

If, as previously assumed, effort and use locate growth-force,
cellular structure will appear in the directions indicated by the
activity of motive-force. It is converted by protoplasm from heat
and chemism, or one only of these. That it does not require dif-
ferentiated *^ motive-force" as a source, is proved by the growth
of plants, which have no motion proper.

Growth-force, by its ^^ repetitive " action,* creates organs.
These at first will be extremely simple, but, as machines, at once
increase the power of the animal to produce motive-force by con-
version, whether the machine be a digestive apparatus for the ap-
propriation of the material, or a mechanical one for the exercise
of the force, the former necessarily preceding the latter in time.

With the increased power of assimilation (digestion) comes a
larger amount of material for increased exhibition of growth-force,
a part being burned or otherwise converted into the force, and a
part remaining as the material from which the cells are construct-
ed. In the latter 23art of the growth-period a considerable portion
is usually consumed for motive-force.

In the history of the material environment, various changes of
condition succeeded each other. Changes of level took place ;
waters were purified by precipitation of chemical compounds ;
fresh waters were established ; the atmosphere deprived of various
gases ; new mineral, and especially vegetable, products took their
appropriate places. All these offer a vast variety of food-supply
and opportunity for the pleasurable discharge of motive-force, and,
under the laws pointed out, efforts of animals were directed in va-
rious lines, as the conditions presented themselves. Thus execu-
tive organs were produced of varied character. Some acquired
limbs and others wings for transportation from place to place.
What a vast addition to their impressions must have been acquired
by the first animals which could thus leave the place of their
birth ! How many new "contiguities" were established, and how

* «

See " Method of Creation," on the Law of Repetition.

EVOLUTION AND ITS CONSEQUENCES. 37

many new habits originated ! Look again at the acquisition of
teeth. From a soft uniform diet the animal no doubt gradually
learned to appropriate hard substances, and what a world of ex-
perience and consequent habit must have been at once placed in
its way !

These acquisitions are of course mental, and include both
kinds of contiguity, viz., that of succession in time, and that of
association through resemblance. Animals choose between objects
chiefly in accordance with the first mode, but are not lacking in
the second quality. As an example of the latter, classification ac-
cording to color is exhibited by some birds, which choose brightly
colored objects and reject dull ones — the Australian bower-bird,
for instance.

As is well known to metaphysicians, these acquisitions lead to
'^predication" and "forethought." Thus a hound becomes ac-
quainted with the habit of a buck or rabbit in doubling, or in fol-
lowing a given circuit. The recurrence of the chase recalls the
habit in consequence of contiguity of the impression of the former
pursuit of the animal and the course it took. The hound then
supposes or " predicates " that the deer will repeat the course. We
know that some do so from the fact that they have been observed
to cut off the curves in the animal's track, or to station themselves
at the point where the deer, for instance, will pass. In the sec-
ond act forethought is also involved. The hound sacrifices the
lesser pleasure of the chase for the greater one of securing the
prey. In forethought, experience having taught which circum-
stance results in greater and which in less pleasure, action is re-
strained in the presence of the second for the sake of procuring
the first. Thus in ants, immediate pleasure suggests a life of labor
enough for present wants, and ease for the remaining time ; but
the greater pleasure of existence during some time of scarcity has
induced some of them to lay up a store, which has develoj^ed into
the complete protection against winter they display in cold cli-
mates.

In the cases cited it is perfectly evident that the hound would
never have learned to predicate had he not had limbs to bring him
in contact (by pursuit) with the habits of the buck. Nor would
the ant have learned to provide if it had not been furnished with
the jaws necessary to the excavation of chambers and the carrying
of food. And neither would have performed these mental acts
had they not possessed nervous centers capable of sensation, reten-

38 GENEKAL EVOLUTIOi^.

tion, and classification. But the development of these qualities
depended on the possession of the executive organs.

Thus intelligence of various degrees has resulted — first, from
possession of executive organs ; secondly, establishment of con-
tiguities by their use ; tliirdly, from classifications based on con-
tiguities.

There are two notable examples of the great advance in mental
accomj)lishment inaugurated by the acquisition of an executive
organ. The first is the acquisition of the hand by the monkey.
Any one who has compared their manners with those of the si3e-
cies of unguiculate (clawed) animals — as, for example, the dog —
must be struck by the immense advantage possessed by the for-
mer. To begin with, it renders the monkey an expert climber
and catcher of moving objects. Then he greatly increases his
habits of observation by the facility with which he brings objects
before his eyes. The minuteness of his criticism is aided by his
power of manipulating with his fingers. He learns the results of
tlirowing. A cautious monkey, set on a strange animal or per-
son, does not rush at them to bite like the dog, but takes the more
refined method of throwing sticks and stones. In obtaining ob-
jects, if they be out of reach, a monkey uses a stick to draw them
in with. In a Cetus capucinus, in my possession, a leather strap
was preferred, and was thrown with great dexterity, and the ob-
ject always secured by drawing it nearer in loops of the strap. If
the strap were sometimes thrown out of reach, the monkey would
use a stick or poker in order to obtain it again. All this would
have been quite imj^ossible without a hand. This facility has not
been lost on the intelligence of the monkeys. Their curiosity is
proverbial, and no animal can compare with them as successful
thieves ; moving m bands, with watchers stationed, and taking
pains to store their booty in their cheek-pouches while they have
opportunity, and not wasting time in eating exclusively.

Another instance is that of man. Here the acquisition con-
sisted of vocal organs capable of speech. Any means of com-
municating and recording thoughts had the stupendous conse-
quence of rendering the acquisitions of one man or class of men
the common property of all. Another consequence, equally im-
portant, is the preservation of successive races of men from the
necessity of passing through the experiences of those that pre-
ceded them, and the enabling them to commence their intellectual
life nearly where the others left off. So great would necessarily

EVOLUTION AND ITS CONSEQUENCES. 39

De the location of activity in the brain, that its stages of growth
would be the principal changes of structure to be witnessed in
human history, together with those which should result from loss
of growth-force in other regions by abstraction.

To return to the material aspect of the case. The discrimina-
tion between pleasure and pain locates motive-force, which is
derived from without. Motion or use locates growth-force, also
derived from without, and thus produces organs out of material
derived from without. These organs diversify the directions of
motion. From new movements arise new pleasures and pains,
and motion is again '* located" in its exhibitions in some particu-
lar directions, and restrained in others. These directions depend
on external circumstances at the first. The determination of
motion to certain lines locates growth-force in those lines, and
new parts are produced, which are further executive organs and
types of structure. We now repeat the circuit. New executive
organs introduce new contiguities, the number depending on the
general complication of the animal in connection with that of the
organ, and new pleasures and pains result. The pleasures again
determine activity, and, under the circumstances already men-
tioned, growth-force is again located.

In these facts lies the explanation of the principle of direction
or location of executive structures about the head, termed by
Prof. Dana ^^cephalization." The increasing demands of in-
telligence locate growth-force round its organ, the brain, etc.,
while such location reacts by furnishing means of increased ac-
tivity of mind.

These conjunctions of growth with executive capacity, consti-
tute a class of *^ expression points"; points attained without
leaps, and abandoned without abruptness, but constituting great
steps of progress, pregnant with future results.

The part played by ^Mntelligent selection" remains to be
considered. I have heretofore spoken only of variation of types,
and not dwelt on their persistence. This is a most important
consideration, for most men see a great deal more of the latter
than the former. Species present their characters intact for long
periods, and many structural peculiarities have had great range
in time.

I recur to the origin of the "location of growth-force," i. e.,
the direction of motive-force. This is located by the appreciation
of pleasure and pain. Now, every one knows that different ani-

40 GENERAL EVOLUTION.

mals of the same species yary exceedingly in their sensitiveness
to exterior influences ; that is, they differ in the degree in which
the same object affects their consciousness. That which excites
one is unnoticed by another ; what fills one with alarm scarcely
rouses the attention of another. It is well known also that differ-
ences in the power of retention are to be found in the same spe-
cies of animals. The variations in persistence of memory are
very great. While, therefore, one individual of a species will ac-
quire a store of '^ contiguities," another of the same will possess
but few. In other words, the degree with which objects are
impressed on the consciousness, and the degree with which they
are returned to the consciousness, vary greatly in the same spe-
cies. Here we have the basis for the origin of totally different
unconscious habits and reflex actions, and consequent divergences
in the "location of growth-force."

Those in which these impressibilities are most highly devel-
oped will accumulate mental acquisitions most rapidly ; in other
words, they will be the most intelligent of their species. While
others follow the old routine of once acquired and then inherited
habits, those in whom consciousness most frequently recognizes
events will originate new acts and new habits.

Intelligence is a conservative princijole, and always will direct
effort and use into lines which will be beneficial to its possessor.
Here we have the source of the fittest — i. e., addition of parts by
increase and location of growth-force, directed by the influence of
various kinds of compulsion in the lower, and intelligent option
among higher animals.

Thus, intelligent choice, taking advantage of the successive
evolution of physical conditions, may be regarded as the originator
of the fittest, while natural selection is the tribunal to which all
the results of accelerated growth are submitted. This preserves
or destroys them, and determines the new points of departure on
which accelerated growth shall build.

If the above positions be true, we have here also the theory of
the develoi3ment of intelligence and of other metaphysical traits.
In accordance with it, each trait appropriates from the material
world the means of perpetuating its exhibitions by constructing its
instruments. These react by furnishing increased means of exer-
cise of these qualities, which have thus grown to their full expres-
sion in man.

11.

ON THE OEIGm OF GENERA.

Introduction. — The present fragmentary essay is a portion of
what other occupation has prevented the author from completing.
It does not, therefore, amount to a complete demonstration of the
points in question, but it is hoped that it may aid some in a classi-
fication of facts with a reference to their signification. When all
the vast array of facts in possession of the many more learned
than the writer are so arranged, a demonstration of the origin of
species may be looked for somewhere in the direction here at-
tempted to be followed.

Conclusions of any kind will scarcely be reached, either by
anatomists who neglect specific and generic characters, or, secondly,
by systematists who in like manner neglect internal structure.
Such will never perceive the system of nature.*

ANALYSIS OF THE SUBJECT.

I. Relations of allied genera.

First : in adult age.

Second : in relation to their development.

a. On exact parallelism.

/8. On inexact or remote parallelism.

y. On parallelism in higher groups.

8. On the extent of parallelisms.

II. Of retardation and acceleration in generic characters.
First : metamorphoses in adult age.

a. The developmental relations of generic and specific char-
acters.

* It might seem incredible that either class should systematize with confidence,
yet a justly esteemed author writes even at the present day, " However, there is
scarcely a systematist of the present day who does not pay m.ore or less attention to
anatomical characters, in establishing the higher groups!" (The italics are our
own.) As though a system were of any value which is not based on the whole struct-
ure^ and as though loxcer groups were only visible in external characters ; in a word,
as though external (muco-dermal, dental, etc.) characters were not " anatomical " !

42 GENERAL EVOLUTION.

y8. Probable cases of transition.
y. Ascertained cases of transition.
Second : earlier metamorphoses.

8. The origin of inexact parallelisms.

III. Eelations of higher groups.

a. Of homologous groups.

p. Of heterology.

y. Of mimetic analogy.

IV. Of natural selection.

a. As affecting class and ordinal characters.
p. As affecting family characters.
y. As affecting generic characters.
8. As affecting specific characters.
c. On metaphysical species.

V. Of epochal relations.

The laws which have regulated the successive creation of or-
ganic beings will be found to be of two kinds, as it appears to the
writer. The first, that which has impelled matter to produce
numberless ultimate types from common origins ; second, that
which expresses the mode or manner in which this first law has
executed its course, from its commencement to its determined
end, in the many cases before us.

That a descent, with modifications, has progressed from the
beginning of the creation, is exceedingly probable. The best
enumerations of facts and arguments in its favor are those of
Darwin, as given in his various important works, *'The Origin of
Species," etc. There are, however, some views respecting the
laws of development on which he does not dwell, and which it is
proi^osed here to point out.

In the first place, it is an undoubted fact that the origin of
genera is a more distinct subject from the origin of species than
has been supposed.

A descent with modification involves continuous series of or-
ganic types through one or many geologic ages, and the co-exist-
ence of such parts of such various series at one time as the law of
mutual adaptation may permit.

These series, as now found, are of two kinds : the uninter-
rupted line of specific, and the same uninterrupted line of generic
characters. These are independent of each other, and have not,
it appears to the writer, been developed pari passu. As a general

ON THE ORIGIN OF GENERA. 43

law, it is proposed to render highly probable that the same specific
form has existed through a succession of genera, and perhaps in
different epochs of geologic time.

With regard to the first law of development, as above proposed,
no one has found means of discovering it, and perhaps no one ever
will. It would answer such questions as this : What necessary-
coincidence of forces has resulted in the terminus of the series of
fishes in the perches as its most specialized extreme ; or, of the
Batrachia, in the fresh- water frogs as its ultimum ; or, of the
thrushes, among birds, as their highest extreme : in a word, what
necessity resulted in man as the crown of the mammalian series,
instead of some other organic type ? Our only answer and law for
these questions must be, the will of the Creator.

The second law, of modes and means, has been represented to
be that of natural selection, by Darwin. This is, in brief, that a
disposition to a general variation on the part of species has been
met by the greater or less adaptation of the results of such varia-
tion to the varying necessities of their respective situations. That
the result of such conflict has been the extinction of those types
that are not adapted to their immediate or changed conditions,
and the preservation of those that are.

In determining those characters of plants and animals which
constitute them what they are, we have, among others of higher
import, those which constitute them species and those which con-
stitute them genera. What we propose is : that, of the latter,
comparatively very few in the whole range of animals and plants
are adaptations to external needs or forces, and of the former a
large proportion are of the same kind. How, then, could they owe
their existence to a process regulated by adaptation ?

Darwin is aware of these facts to some degree, but, as already
said, he does not dwell on them. Where he does, he does not at-
tempt to account for them on the principle of natural selection.

There are, it appears to us, two laws of means and modes of
development : I. The law of acceleration and retardation. II.
The law of natural selection.

It is my purpose to show that these propositions are distinct,
and not one a part of the other : in brief, that, while natural selec-
tion operates by the ^'preservation of the fittest," retardation and
acceleration act without any reference to '^ fitness" at all; that,
instead of being controlled by fitness, it is the controller of fitness.
Perhaps all the characteristics supposed to mark generalized groups

44 GENERAL EVOLUTION.

from genera up (exceiDting, perhaps, families) have been evolved
under the first mode, combined with some intervention of the sec-
ond, and that specific characters or species have been evolved by a
combination of a lesser degree of the first with a greater degree of
the second mode.

I propose to bring forward some facts and propositions in the
present essay illustrative of the first mode.

I. OJT THE KELATIOXS OF NEAKLY ALLIED GENERA.

First. The writer's views of the relations of genera have al-
ready been given at the close of an *' Essay on the Cyprinoid
Fishes of Pennsylvania."* It is easy enough to define isolated
genera which have few immediate afiines ; but among extensive
series of related forms the case is different. One principle, how-
ever, pervades the conception and practice of all zoologists and
botanists, which few take pains to analyze or explain. It is
simply that they observe a successional relation of groups, by
which they pass from one type of structure to one or several other
types, and the presence or absence of the steps in this succession
they regard as definitions of the genera.

It is true that the reader will often find introduced into diag-
noses of genera characters which indicate nothing of this sort. It
is often necessary, indeed, to introduce characters which are not
peculiar to the genus characterized, for the sake of distinguishing
it from similar ones of other series, but this only in an imperfect
state of the record. Moreover, the ability of the writer to distin-
guish genera being thus tested, he too often fails by introducing
family and specific characters, or by indulging in an unnecessary
redundancy. In general, it may be said that adjacent genera of
the same series differ from each other by but a single character ;
and, generally, that the more remote differ by characters as numer-
ous as the stages of their remove.

It is precisely as, among the inorganic elements, we pass from
the electro-negative, non-oxidizing extreme of the halogens, with
fluorine as the extreme, to the electro-positive, violently oxidizing
extreme of the alkaline metals, whose extreme is potassium, by
steps whose relative position is measured or determined first by
these tests ; and as these steps have each their included series of

* "Trans. Amer. Philos. Soc," 1866, from "Proc. Acad. Nat. Sci.," Phil., 1859,
p. 332.

ox THE ORIGm OF GENERA. 45

bodies, characterized by tlieir successive relations on the lower
level of a subordinate range of characters. This principle is dis-
tinctly admitted by many zoologists,* those who deny it generally
failing to perceive it because they attempt to gauge a major scale
by characters which are really the test of one or all of the subordi-
nate or included scales. It holds true of most of the groups of
organic beings ; thus the class is a scale of orders, the order of
tribes. I will not now say that the tribe is a scale of families, as
the case is here much modified ; but what is chiefly to be consid-
ered in this essay is, that the family is composed of one or several
scales of genera.

Second. Now, the more nearly allied genera are, the more
surely will these generic steps be found to fall into the direct line
of the steps of the development of the highest, or that with the
longest scale, the former being truly identical with the latter in
generic characters. Less allied genera will offer an inexact or in-
complete imitation of such identity — some additional character
being present to disturb it. Such genus belongs to another
series, characterized by the disturbing feature, whose members,
however, l)ear to each other the relation claimed above for such.

The relation of genera, which are simply steps in one and the
same line of development, may be called exact parallelism ^ while
that of those where one or more characters intervene in the
maturity of either the lower or higher genus, to destroy identity,
may be called incomplete parallelism.

The latter relation has been dwelt on by von Baer, Agassiz, and
other writers, but none have accepted the existence of exact paral-
lelism, or seen its important relation to the origin of genera.

Third. That the lowest or most generalized terms or genera
of a number of allied series will stand to each other in a relation
of exact parallelism. That is, if we trace each series of a number,
up to its lowest or most generalized genus, the latter together will
form a series, similar in kind to each of the sub-series ; i. e., each
genus will be identical with the undeveloped conditions of that
which progresses the farthest, in respect, of course, to the char-
acters which define it as a series.

Those characters of the skeleton which we are accustomed to
call embryonic are only so because they relate to the develop-

* Prof. Bronn, in his " Classen u. Ordnungen des Thierreiches," has everywhere
a chapter on " Die aufsteigende Rcihe" ("the ascending scale").

46 GENERAL EVOLUTION.

mental succession witnessed in animals at the present time.
Characters not so called now were probably as much so at one
period now passed. Hence embryonic characters of the bony
system do not, as I have often had occasion to observe, charac-
terize the types of the highest rank, but only subordinate divis-
ions of them. Thus the elasmobranchs are i:)robably rejoressed
forms of groups of a really higher grade than the bony fishes, or
teleostei, which may be known to us. In their early presence in
the geologic series we have evidence of the first beginning of a
higher type.

In the same manner it has been discovered that the molecular
aggregation of the elementary substances does not characterize
their highest or most distinct series, but rather the substances
themselves within the group or family to which they belong.
The gaseous, liquid, and solid molecular conditions, being charac-
ters distinguishing otherwise allied substances in the same way
morphologically (we can not say yet developmen tally), as the car-
tilaginous, osseous, and exostosed or dermosseous characters dis-
tinguish otherwise nearly allied genera.

The *^family" group embraces one or many of such series.
If we trace the series in scA^eral families to their simplest or most
generalized terms or genera, and compare them, we will not find
the relation to be one of exact j)arallelism in the series of the
** order," so far as our present knowledge extends, but, in a devel-
oj)mental sense, one of divergence from the commencement.

If we could know the simplest known terms or family charac-
ters of a number of groups of families, or *^ orders," we would
probably find them to represent a series of exact parallelism,
though to find such simplest terms we must go far into past
periods, since the higher the group the more extensive the range
of its character, and the less likely to be found unmixed with ad-
ditions and extensions, in modern times.

Finally, the series of classes is in the relation of the essential
characters of the same, as expressed in their now extinct, most
generalized and simple representatives, also one of " exact paral-
lelism.''

a. Examples of Exact Parallelism,^

1. As an example we may take the genus Trachycephalus
{Batrachia anurd). Nearly allied to it is the genus Osteo-

* In generic series.

ON THE ORIGIN OF GENERA. 47

cephalus, wliicli differs in the normal exostosis of the cranium
not involving the derm, as in the former. Close to this is
Scytopis, where the fully ossified cranium is not covered by an
exostosis. Next below Scytopis is Hyla, where the upper surface
of the cranium is not ossified at all, but is a membranous roof
over a great fontanelle. Still more imperfect is Hylella,* which
differs from Hyla in the absence of vomerine teeth. Now, the
genus Trachycephalus, after losing its tail and branchiae, pos-
sesses all the characters possessed by the genera Hylella and Hyla,
either at or just before the mature state of the latter, as the
ethmoid bone is not always ossified in advance of the parietals.
It soon, however, becomes a Scytopis, next an Osteocephalus,
and finally a Trachycephalus. It belongs successively to these
genera, for an exhaustive anatomical examination has failed to
reveal any characters by which, during these stages, it could be
distinguished from these genera.

Now, it would be a false comparison to say that the young of
Trachycephalus was identical with the genus Agalychnis, which
in truth it resembles, because that genus is furnished with one
other character — the presence of a vertical pupil — and belongs to
another series in consequence, which is represented as yet, with
our present imperfect knowledge — or perhaps imperfect fauna —
by three genera only.

2. The lowest type of the near allies of our common fresh-
water frogs is the genus Eanula, where the prefrontal bones are
narrow strips on each side the ethmoid cartilage ; the ethmoid
cartilage itself entirely unossified above, and the vomerine teeth
very few and on a small elevation. There are two species, R.
affinis and R. palmipes.\ The other species have the ethmoid
cartilage ossified above, at least beneath the extremities of the
frontoparietals.

Those of the latter most like Eanula possess the same type of
narrow prefrontals, separated by a broad area of cartilaginous
ethmoid, and fasciculi of teeth. Of this type is Rana delalandii,
and probably R. porosissima, Steind., of the South Ethiopian
region. Other species of the same type extend their vomerine
patches into lines ; such are R. mascariensis, R. fasciata, R.
oxyrhynchus, R. grayi, and other South African species.

* I refer to H. carnea m., not having Reinhardt and Liitken's type of this genus,
f These species are now believed to be identical, but three others have been dis-
covered (1886).

48 GENERAL EYOLUTION".

The prefrontals are subtriangular, and approacli eacli other
more or less in the numerous species of North America and of
the Regio Paleearctica, while generally the vomerine teeth are in
fascicles or yery short series. In the -Ethiopian Rana fuscigula
the prefrontals unite on the median line, roofing over the ethmoid
cartilage and reducing it, while the vomerine teeth are in very
short lines.

In the species of the Palaeotropical region, Rana tigrina, R.
vittigera, R. cyanophlyctisy R. grimniens, R. liexadactyla, R.
corrugata, R. ehrenhergii, R» gracilis, and the Ethiopian R. occi-
pitalis, the prefrontals not only unite solidly (the suture remain-
ing on the median line), but extend and closely fit to the fronto-
parietals. The vomerine patches have lengthened out into series.

Now, the young of the latter type of Eana (I take as an ex-
ample the R. tigrina, one of the most abundant and largest of
Indian frogs) presents the subtriangular prefrontals neither in
contact with each other or with the frontoparietals, and the
vomerine series is much reduced ; in fact, it belongs in all
respects to the Palsearctic grouj). I have not examined younger
specimens, but have no doubt they are like those of the Palse-
arctic ; which are, in their young stage, precisely of the type
of the Ethiopian Rana, with fasciculate teeth like the young of
those of the same region with teeth in series, since the prefrontals
are still more reduced, becoming linear. Finally, the first stage
of the Nearctic Rana, after losing the larval tail, is the genus
Ranula, having linear prefrontals, minute vomerine teeth, and
the ethmoid ring cartilaginous above.

These points of structure are of generic quality, but I have
not regarded any group as sufficiently defined to be so regarded,
except Ranula, as the adults of some species appear not to be con-
stant in possessing them. Thus a very large Rana catesleyana
sometimes exhibits prefrontals in contact on the median line,
while it is difficult to say whether R. areolata of North America
is of the Nearctic type so much as of the Ethiopian. Neverthe-
less, the groups are generally quite geographically restricted.

3. A similar relation exists between the genera Hyperolius,
Staurois, and Heteroglossa in respect to the prefrontal bones and
the separation of the outer metatarsi, and —

4. Between Ixalus, Rhacophorus, and Polypedates also, in
reference to vomerine teeth, bifurcation of last phalange, and
dermoossification of the cranium.

ON THE ORIGm OF GENERA. 49

5. When the larvae of certain salamanders (Spelerpes) possess
branchiae, they also lack one digit of the hind foot, also the max-
illary, nasal, and prefrontal bones, and exhibit a broad continuous
palatopterygoid arch, in close contact with the parasphenoid.
The prootic is separated from the exoccipital by a membranous
space, and the exoccipitals themselves are not yet united above
the foramen magnum. There is at the same time a series of
splenial teeth. Both ceratohyals are confluent, the posterior is
present, and there are but three superior hyoid arches. After
they lose the branchiae, the hinder foot, which has four toes only
for a time, gradually adds another at first rudimental digit, in the
Mexican species ; in most North American species the fifth digit
appears at an early larval stage. Five digits are finally present in
all Spelerpes.

We have thus four combinations of the above characters, at
different periods of the life history of certain (but not of all) of
the species of Spelerpes. There exist four permanent series of
species or genera, equivalent to these stages. The well-known
^^perennibranchiate" J^ecturus is nearly identical with the first,
Batrachoseps with the second, the half-toed Spelerpes with the
third, and the typical Spelerpes is the last.

In one character of generic value only do I find that Necturus
differs from the early larval Spelerpes. It closes the premaxillary
fontanelle with which it commences, by an approximation of the
premaxillary spines, but not by a sutural union, as takes place in
Amblystoma. It thus, in this one point, advances a stage beyond
the condition to which Spelerpes attains, though it may be a
question whether such a closure without union should not be
classed among the specific characters by which iV. maculatus dif-
fers from the young of the various Spelerpes, as they do from
each other. Characters of the latter kind are the following : in
N. maculatus the frontals are more deeply emarginate behind ; it
has little or no ala on the inferior keel of the caudal vertebrae,
which is prominent in Spelerpes larvae.

It may be that the parallelism in the case of Spelerpes is inex-
act by one character, and that a strictly developmental one ; or
it may be regarded otherwise.*

6. It is well known that the Cervidae of the Old World devel-

* Necturus differs from these larvas by another and more important character,

viz., the presence of the os intercalare.
4

50 GENERAL EYOLUTIOK

op a basal snag of the antler (see Cuvier, " Ossem. Fossiles";
Gray, " Catal. Brit. Mus.") at the third year ; a majority of those
of the 'New World (genera Cariaciis, Subulo) never develop it
except in ^'abnormal" cases in the most vigorous maturity of the
most northern Cariacus (C. virginianus) ; while the South Ameri-
can Subulo retains to adult age the simple horn of the second
year of Cervus.

Among the higher Cervidae, Rusa and Axis never assume char-
acters beyond an equivalent of the fourth year of Cervus. In
Dama the characters are on the other hand assumed more rapidly
than in Cervus, its third year corresponding to the fourth of the
latter, and the development in after years of a broad plate of
bone, with points, being substituted for the addition of the corre-
sponding snags, thus commencing another series.

Returning to the American deer, we have Blastocerus, whose
antlers are identical with those of the fourth j^ear of Cariacus.

Now, individuals of the genus Cervus of the second year do
not belong to Subulo, because they have not as yet their mature
dentition. Rusa, however, is identical with those Cervi whose
dentition is complete before they gain the antlers of the fifth
year. When the first trace of a snag appears on one beam of
Cariacus virginianus, the dentition includes the full number, but

there remain - milk molars much worn and ready to be shed.

Perhaps the snag is developed before these are displaced. If so,
the Cariacus is never a Subulo, but there can be little doubt that
the young Blastocerus belongs to that genus before its adult char-
acters appear.

7. Leidy states * that certain Perissodactyl remains, contain-
ing a foot of a horse, contained the teeth of a genus, Protohippus,
which has the permanent teeth of Equus, and the deciduous
dentition of Anchitherium. He observes : *^The deciduous and
permanent dentitions of both these genera are alike ; therefore
the new genus is in early life an Anchitherium, and later in life a
true horse." This is therefore a case of exact parallelism, always
providing that the Protohippus has not added to its immature
equine characters others in other parts of the body, which in-
validate the identity. In the latter case it will still be an inter-
esting example of the *^ inexact parallelism." \

* "Proceed. Acad. Xat. Sci," 1858, p. 7.

f This is not a proper example of parallelism if, as some zoologists believe, the

ON THE ORIGIN OF GENERA. 51

8. It is well known that the Cephalopoda form a number of
series of remarkable regularity, the advance being, in the first
place, in the complication of the folds of the external margins of
the septa, and, in the second place, in the degree of involution of
one or both extremities of the shell to the spiral ; third, in the
position of the siphon.

Alpheus Hyatt, in an important essay on this subject,*
points out that the less complex forms are in many cases iden-
tical with the undeveloped conditions of the more complex.
He says : ^^ There is a direct connection between the position of
a shell, in the completed cycle of the life of this order, and its
own development. Those shells occujoying the extremes of the
cycle" (in time), ^Hhe polar forms, being more embryonic than
the intermediate forms, f The first epoch of the order is
especially the era of rounded, and, in the majority of the spe-
cies, of unornamented shells with simple septa ; the second is
the era of ornamentation, and the septa are steadily complicat-
ing ; in the third the complication of the septa, the ornamen-
tation, and the number of species, about twice that of any
other epoch, all combine to make it the zenith of development
in the order ; the fourth is distinguishable from all the preced-
ing as the era of retrogression in the form, and partially in the
septa.

** The four periods of the individual are similarly arranged,
and have comparable characteristics. As has been previously
stated, the first is rounded and smooth, with simple septa ; the
second tuberculated, and the septa more complicated ; the third
was the only one in which the septa, form, and ornamentation
simultaneously attained the climax of individual complication ;

deciduous or temporary dentition is not a remnant of the primitive dentition, but is
a later product of mammalian evolution. If it be a case of parallelism, it is inexact,
because the genus Protohippus was discovered by the writer to have three toes,
while Equus has but one.

* " Memoirs Boston Soc. Nat. Hist.," 1866, p. 193.

f He adds here : " Although in regard to geological sequence and structural po-
sition one of the extremes must be of higher geological rank." The " highest " ex-
treme will be of higher geological rank, according to the complexity of structure and
length of developmental scale, whether it come at the middle or end of the history
of the class in time. If, as has been the case, so far as known, a decline has termi-
nated the history of a class, its later forms are zoologically loicer than its older
ones. Hence the adjective high is only appropriate to types of the latter kind^
when used as synonymous with extreme.

52 . GENERAL EVOLUTION.

the fourth, when amounting to anything more important than
the loss of a few ornaments, was marked by a retrogression of the
whorl to a more tabular aspect, and by the partial degradation of
the septa."

I will here quote an entirely antagonistic statement of
Bronn's,* as follows : ** In the development of lamellibranchiate
mollusks it is not possible to estimate the successional changes of
one genus by those of another, though nearly related ; so diverse
are the most significant relations in the manner of progress among
nearest allies. Therefore, embryologic indications are throughout
useless in classification, and it is necessary to keep carefully se^oa-
rate the statements of observations on development of a given
species, and not transfer such facts to the history of another spe-
cies for the purjDose of completing it. We can not even range
these histories in conformity with family groups." For us this
statement, though no doubt largely true, is an indication of im-
perfection— first, of knowledge of true affinities of recent, but
esi^ecially of extinct adults, and, second, of imperfection of knowl-
edge of development. The position api^ears to be based on nega-
tive evidence, while the opposing can and does stand on nothing
but positive.

/?. Examples of the Inexact Parallelism.

1. The genera of the batrachian family Scaphiopodidae form
a series of steps differing a little more than as repressions or joer-
manent primary conditions in the development of the highest, f
Thus two of the genera, which are North American, maintain
their tubae eustachii and tympanum through life, while three
European lose them at an early period. J; The three European
genera also advance beyond the larval character of the Ameri-
can in the ossification of the basis of the xiphisternum into a
broad style. Thus we have two series established, which differ
only in the two characters named. Each shows its develop-
mental steps in a similar manner, the European series extending
further ; thus :

* " Classen u. Ordnungen des Thierreichs," iii, p. 445.

f See "Journal Academy," Philadelphia, 1866, on Areifera.

X According to Bruch and Tschudi, in Pelobates. I have found traces of the
eustachian diverticula, in a tailed Pelobates fuscus, whose body measured 1 in. 4 lin.,
from Mus. Peabody Institute, Salem, Mass.

ON THE ORIGIN OF GENERA. 53

European, North American,

1. Temporal fossa over arched.

Oultripes. * *

Temporal roof not ossified.

2. Fronto-parietal bones ossified, involving

derm.

Pelobates. Scapliiopns.

3. Fronto-parietals ossified, distinct from

derm.

* * (Unknown.) * *

4. Fronto-parietals not ossified, distinct

from derm.

Didocus. Spea.

In this case Didocus can not be said to be identical as a genus
with an undeveloped stage of Oultripes, since, while the cranium
of the latter is in the condition of Didocus, it bears a long tail,
and the limbs are but little developed. Nor is Didocus identical
with the undeveloped condition of Pelobates, since both cranium
and limbs of the latter are developed before the tail is absorbed.
Nor is Pelobates identical with the undeveloped condition of Oul-
tripes, since, while the cranium of the latter is that of the former,
the limbs and tail are still larval. The same relations exist be-
tween the other members of the family; The genus Scaphiopus
is not an undeveloped form of Pelobates as to its auditory organs,
for, when the latter is identical with the former in this respect, it
bears otherwise entirely larval characters. Nor is Spea an arrested
Scaphiopus, the relation being here precisely that between Dido-
cus and Pelobates. Spea approaches more closely ah arrested
Didocus in all respects, but that when the latter possesses the au-
ditory apparatus * of the former, it is a larva in limbs and tail,
and that it loses this apparatus before reaching the other charac-
ters of Spea. The relations of these genera, as compared with
those of the Trachycephalus, Oystignathidse, and Bufo series, may
be represented as follows : the lines represent the developmental
scale of each.

This is an example of the simplest case of inexact parallelism,
as distinguished from the exact parallelism or identity. As the
fauna of the present period is but a fragment, so the simple inex-

* The possession of eavum tympani and tuba Eustachii in the undeveloped con-
dition of this genus is only assumed from its close relation to Pelobates.

GENERAL EVOLUTION".

Relations between the terms of

the

different series, Heterol-

ogy or Remote Parallel

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act is a more frequent relation than the
exact, while the more complex inexact
relation is still more common. The
greater the inexactitude, the more fre-
quently do such parallels occur till we
have those of the most remote character,
as, for instance, the parallelism between
the different stages of the development
of the mammal, in the structure of the
heart and origins of the aorta, and the
existing classes of vertebrates. The re-
lation of these facts to the origin of
genera will be noted hereafter.

It will be borne in mind that in the
Scaphiopodidae the generic types are
identical for a long portion of their
developmental history. (See figures on
plate iv for the representation of these
facts. )

2. In both Perissodactylous and Ar-
tiodactylous Mammalia, certain types
develop their family character of ca-
nines at the earliest appearance of den-
tition, others not till a comparatively
late period of life (Equus), and the ex-
treme individuals never produce them.

3. Among cetaceans the genus Orca
maintains a powerful and permanent
series of teeth, which is an important
generic character. In Beluga the se-
ries is shed in old age, in Globiocepha-
lus, or the Caing whales, they are shed
at middle age, while in the Balsenidse,
of which the absence of teeth is an es-
sential character, these organs are de-
veloped and absorbed during fcetal life
(Eschricht). Though the condition
of the teeth is not of systematic value
in the two named intermediate genera,
it is the important feature in the his-
tory of progress to such value.

OE" THE ORIGIN OF GENERA. 55

4. Among the tortoises, the Testudinidae rapidly extend the
ribs into a carapace, which fits closely the marginal bones, while
equally early in life the elements of the sternum unite together.
This is also the case with most Emydidee ; among whose genera,
however, we find the transitional scale. In Dermatemys and
Batagur the carapace is very late in attaining its complete ossifi-
cation, while the plastron is early finished. In Chelydra, on the
other hand, while the carapace is even more slowly developed, the
plastron is never free from its larval fontanelles. In the marine
turtles neither plastron nor carapace is ever completed, while
in the Trionychidag the marginal bones are also entirely unde-
veloped.

In order that this last illustration be a true one for the theory
in question, as applied to ihQ families, these developmental char-
acters should be the true distinctive features of these families re-
spectively. This, as is well known, they are not. The Chelo-
niidse are characterized by the form of their anterior limbs, which
is in an adaptive structure, while the Testudinidae similarly are
distinguished by an extreme opposite modification of foot-struct-
ure, adapted to an extreme difference of habit. Here there is an
example of the co-working of both laws. Nevertheless, we only
claim at present to show the developmental relation of genera of
the same family and the same series. This we see among the
Emydidae.

5. In the important character of the sciitellation of the tarsi
among the Passerine birds, the ^^boot" appears early in life in the
highest Oscines, later in the lower, and does not ai:)pear at all in
the majority. In respect to the still more important feature of
the long posterior plates which appear very early in most Oscines,
in the Myiadestes type * they appear late, the squamse remaining
long, while the Clamatores never develop the plates, not advancing
beyond the infantile squamous stage.

6. It has been shown by Falconer that the genera of great
Proboscidians form a remarkably regular and graded series, dis-
tinguished by their dentition. These are Dinotherium Kaup,
Trilophodon Falc, Mastodon Cuv., Pentalophodon Falc, Stego-
don Falc, Loxodon F. Cuv., and Elephas Linn. In the first
there are but two cross crests on the third molars, and a pair of
permanent mandibular tusks ; in the second, three cross crests

* Baird, " Review of Birds of North America."

56 GENERAL EVOLUTION.

and mandibular tusks permanent in some males ; in the third,
four cross crests and the mandibular tusks variable ; in the fourth,
five cross crests on the third molar ; tusks unknown. In Stego-
don the mandibular tusks cease to appear, the crests of the third
molar become more numerous, and embrace between them, in the
bottoms of the valleys, a strong deposit of cementum. In Loxo-
don the crests have the whole interspaces filled with cementum,
while the same thing holds in Elephas, with a greatly increased
number of cross crests, which become vertical laminae. The lami-
nar character has become ap2)arent from its rudimental condition
in Stegodon.

'Now, these are stages of development, though not in a con-
tinuous, single line. The shedding of the inferior tusks takes
place earlier and earlier in the genera from Dinotherium, till
they never appear in Stegodon. The molar teeth, it is well
known, present, as they succeed each other from back to front,
a regularly increasing number of transverse crests in the same
species. Thus, in Trilophodon oliioticus the first molar presents
but two, while the last presents six. The last molars of other
genera present a very much increased number. What is it,
then, but that the increased number of crests in the third molar,
definitive of these genera, is an acceleration of growth ; the
fourth in Trilophodon is structurally third in Mastodon, and the
fourth of Mastodon being third in Pentalophodon ; the fourth
of Pentalophodon becoming third in Stegodon, and so to the
end ? This is confirmed from the proved fact of the disap-
pearance of the premolars. They are fewer in Trilophodon
than in Dinotherium, and are soon shed ; they are also early
shed in Mastodon and Stegodon {insig7iis Falc. Caut.), and are
not known to exist in the succeeding types ; the acceleration of
succession of teeth has caused them to be entirely omitted. The
young tooth of Elephas, moreover, is represented by a series of
independent parallel laminae at first, which, when they unite,
form a series of crests similar to the type of the genus Mastodon
and others of the beginning of the series. The deposit of cemen-
tum takes place later, till the valleys are entirely filled up. Thus
the relations of this part of the tooth-structure in the series are
also those of the successional growth of those of Elephas, the ex-
treme of the series.

It would be only necessary to show that two distinct condi-
tions, in any of these respects, occurred among the different indi-

ox THE ORIGm OF GENERA. 57

viduals of the same species of any of tliese genera, to render a
hypothesis of evolution a demonstrated fact.*

It must be here observed that great size indicates little or
nothing as to zoological rank. The greatest species are often not
far removed in affinity from the least ; thus there can be but little
doubt that elephants are not far removed from the rodents, and
the rhinoceros is near the cony. Indeed, in the same genus the
most extraordinary diversity prevails, for we have a very small
elephant of Malta, and in the Miocene of Maryland a fin-back
whale not so large as the new-born young of the fin-backs now
living. Hence the objection to the developmental hypothesis,
based on the great size of the primal Selachians and Ganoids, has
but little weight.

7. Eathke has shown . that the arteria ophthalmica of the
higher Ophidians is originally a branch of the arteria cerebralis
anterior, and that it later forms a connection with the arteria
facialis. This connection increases in strength, while the other
diminishes, until finally its supply of blood is derived from the
facialis instead of the cerebralis.

Eathke has also shown that the cerebral origin of this artery
is continued through life in the three lowest suborders of the ser-
pents, the'Scolecophidia, Catodonta, and Tortricina ; also in the
next succeeding group, the Peropoda.

8. In most serpents the left lung is never developed ; in such
the pulmonary artery, instead of being totally wanting, remains
as a posterior aorta bow, connected with the aorta by a ductus bo-
talli ; serpents without left lung being therefore identical in this
respect with the embryonic type of those in which that lung
exists.

9. Dr. Lespes states that the optic region of the brain of blind
cave Coleoptera, examined by him is similar in structure to that
in the blind larvae of Coleoptera, whose imagos j^ossess visual
organs.

10. t Those Saurians (Uromastix, etc.), in which the pre-
maxillary region is produced into a uniform cutting edge, are
furnished during early stages with a series of premaxillary teeth,
which become gradually fused and confluent with the alveolar
margin. Hence other Acrodonts are equivalent, in this respect,

* This variability has since been shown to exist in species of the M. angmtidens
type (1886).

\ See under section on Acceleration and Retardation.

58 GENERAL EYOLUTIOX.

to the young of Uromastix, etc. The same tiling occurs among
the Scaroid and Labroid fishes. In this most natural family we
find the majority of generic forms provided with a normal com-
plete dentition ; in others (Chaerops, Xiphochilus, Pseudodax,
etc.) the lateral teeth are gradually and normally replaced by a
more or less cutting edge of the mandible ; and finally, in the
Scarina and Odacina, the entire mass of teeth and jaws are coa-
lesced, forming a beak with sharp cutting edges, the single teeth
being still visible in the true Scarus, while they have entirely dis-
appeared in adult Pseudoscarus and Odax.* Thus, in dentition,
the adult Scarus is identical with not fully developed Odax ;
Chaerops, with the teeth less confluent, equals a still younger stage
of Odax, while those with distinct teeth are tiie same in this point
as the embryos of the highest — Odax, etc. I venture to predict
that here will be found a long series of exact parallelism, in which
the different genera, resting exclusively on these dental characters,
will be found to be identical generically with the various stages
of the successively most advanced.

11. Prof. Agassiz states that the absence of ventral fins is char-
acteristic of an embryonic condition of the Cyprinodont fishes.
The genus Orestias does not progress beyond this stage in this one
point. Probably the genus will be found which will only differ
from Orestias in the presence of ventral fins. If so, Orestias will
be identical with an imperfect stage of that genus, if, as will prob-
ably be the case, the fins appear in the latter, after other struct-
ures are fully completed.

yy. Parallelism in Higher Groups.

It is not to be anticipated that the series of genera exhibiting
exact parallelism can embrace many such terms, since compara-
tively few stages in the developmental condition of the same part,
in the highest, would bring us back to a larval condition, which,
as far as we yet know, has no exact parallel among existing genera.
But it is to be believed that the lowest terms of a number of the
most nearly allied of such series do of themselves form another
series of exact parallelisms.

Thus exact parallelism between existing genera of mammals
ceases, with all characters which are larval or foetal, only prior to

* Giinther on Hatteria, "Philosophical Transactions," 186Y, ii. I had already
noticed the peculiar development in Uromastix, but not published it.

ox THE ORIGIN OF GENERA. 59

the assumption of the adult dentition, since among the higher
Mammalia at least we know of no genus which, however similar to
undevelo^Ded stages of the higher, never loses the milk dentition.
It is nevertheless an important fact that among smooth-brained
mammals, or many of them, but one tooth of the second series
appears ; and inasmuch as smooth-brained forms of the higher
orders have become extinct, it is not too much to anticipate that
a type of permanent milk dentition will be found among the ex-
tinct forms of the same high orders.

As an example of exact parallelisms in series of series, I select
the following :

1. In the batrachian family Cystignathidae there are six groups
or sets of genera. In the highest of these we have an ossified cra-
nium and xiphisternum — i. e., in the Cystignathi ; in the Pleuro-
demae the cranium is not ossified, thus representing the Cystigna-
thi while incomplete ; in the Crini^ the xiphisternum is cartilagi-
nous, as well as the fronto-parietal region, being an equivalent of
a still lower stage of the Cystignathi. From this simplest type we
can find a rising series by a different combination of characters ;
thus the Ceratophydes add an osseous cranium to the incomplete
xiphisternum, while two succeeding groups diverge from each
other at the start, the Pseudes loosening the outer metatarsus in
their development to maturity, while the Hylodes add by degrees
a cross-limb to the last phalange. The Ceratophrydes and Criniae
are stages in the development of these ; but neither one of them
is a step in the development of the other. They are measured by
adaptive characters purely.

2. The whole suborder 'of the Anurous Batrachia, to which
the above family belongs, the Arcifera, differs from the suborder
Eaniformia by a character which distinguishes a primary stage of
growth of the latter from its fully developed form. That is, the
Eaniformia present, at one period of their development, a pair of
parallel or over-lapping curved cartilages, connecting the procora-
coid and coracoid bones, which subsequently unite and become
a single, slender median, scarcely visible rod, while the bones
named expand and meet. The first condition is the permanent
and sole systematic character of the Arcifera.*

Ohjection. — It may be objected, by those who have observed

* This may be readily understood by comparing my monograph of the Arcifera,
"Jour. Ac. Nat. Sci.," Phil, 1866, with Duges's work, or Gegenbaur and Parker's
memoir on the Shoulder-Girdle.

60 GENERAL EVOLUTION.

some of these developmental relations, that they are exhibited
by certain single structures only, and not by whole organisms.
These objectors must not forget that the distinctions of those
groujis, which alone we have in one geological period in a relation
of near affinity, exists in single characters only ; and that it is
therefore infinitely probable that the higher groups, when we
come to know their rejDresentatives with the same completeness,
will prove to be separated by single characters of difference also.

3. The following table (pages 63 to 73) is introduced to illus-
trate the relations of groups higher than the preceding. This is
largely measured by the circulatory system, not only as to the
class relations, but also as regards orders. In its less central por-
tions it is, however, definitive of families at times.* (See also
Plate!)

If the reader will comjoare the history of the development of
vertebrates of any class or order, as those of Teleosts and the
lizard by Lereboullet, of the snake and tortoise by Kathke and
Agassiz, and of the bird and mammal by von Baer, he will find
the most complete examples of the inexact paraTlelism of the
lower types with the embryonic stages of the higher. A few
points are selected as examples, from the histories included in a
few of the columns of the table, and given at its end.

Similar parallels may be found to exist in the most beautiful
manner between the adult anatomv and structure of the uroo^eni-

*/ CI?

tal aj)paratus within each class of the series taken separately, as
indicating ordinal relationship. This department is, however,
omitted for the present.

As an example of the homologies derivable from the circula-
tory system, and of the use of the following table, I give the fol-
lowing relations between the types of the origins of the aorta, f

The single ventricle of Teleostei is no doubt homologous with
that of Lepidosteus, and that of Lepidosiren. The arteria vesiccB

* This sketch is not nearly complete, but is published in hopes of its being use-
ful to students. It is compiled from the works of Meckel, Rathke, Barkow, Miiller,
Ilyrtl, Briicke, Stannius, and others, in connection with numerous dissections.

f Prof. Agassiz (" Contrib. Nat. Hist. U. S.," i, p. 285) states that the ven-
tricle of the Testudinata " is not any more identical with the one ventricle of
fishes than with the two ventricles of warm-blooded vertebrata ; for in fishes we
find only one vessel, the aorta, arising from it, while in turtles both the ao7'ta and
arteria pulmonalis start to'^ether from it." We think this statement, which, if true,
is destructive to the asserted homologies of the circulatory system, can not be sub-
stantiated, for the reasons above given.

occ

cul

5 m ao
Central Circulatory System.

ao—

Figs. 1, 2, fish. Figs. 3, 4, batracliian. Fig. 5, reptile. Fig. 6, bird.

Figs. 7, 8, human foetus.

PLATE I.

Figures and Diagrams of the circulatory centers of Vertebrata. Copied from
Gegenbaur and His, mostly enlarged.

Fig. 1. Diagram of the arterial arches of a Fish (species not given).

Fig. 2. Head of an embryonic Teleostean, with the rudiments of the vascular
system (diagrammatic).

Fig. 3. Heart and arterial trunks of a larva of a Salamander.

Fig. 4. Arterial system of the Frog.

Fig. 5 Heart and arteries of an Ophidian (Boa).

Fig. 6. Diagram of the arterial system of the adult Fowl.

Fig. 7. Central circulatory system of Man ; foetus of the second month ; front
view.

Fig. 8. Same as Fig. 7, left side.

V, ventricle of heart.

«, auricle of heart.

s V, sinus venosus of heart.

b a, bulbus arteriosus of heart.

a 6, aorta branchialis.

1, 2, 3, 4, 5, arteriae branchiales.

V 1, 2, 3, venae branchiales.

ao, aorta.

ad, aorta dextra (right).

a 5, aorta sinistra (left).

p, arteria pulmonalis.

db, ductus botalli.

ca, arteria carotis.

cca, common carotid.

Jisc, Isc, right and left subclavian arteries.
i?m,^m, right and left innominatearteries.
cut, arteria cuticularis.
occ, arteria occipitalis.

V c, vena cardinal! s.

V c7, right vena cava.

V s, left vena cava.

vi, inferior (posterior) vena cava.

ces, (esophageal artery.

wi, mesenteric artery.

s, spiracular or branchial fissure.

«, nostril.

dc, ductus cuvieri.

I, lingual artery.

ON THE ORIGIN OF GENERA. (Ji

natatoricB, wliicli is the homologue of the A. pulmonalis of air-
breathers, issues in Lepidosteus from the last vena IrancMcdis,
thus receiving aerated blood from the gills. In Lepidosiren it
issues from the point of junction of two gill-less and two gill-bear-
ing venoR hrancMales, thus receiving mixed blue and red blood, or
blue blood altogether, Avhen the branchiae are not in functional
activity. In Proteus it issues from the last vena branchialis,
where it receives the ductus hotalli of the preceding vein, which,
when the gill is inactive, becomes a gill-less aorta-bow, which brings
it only carbonized blood, which it readily aerates in the swim-
bladder, now become a lung. The ventricle is homologous with
the preceding. In salamanders, where the substitution of the
accessory gill arches by the ductus hotalli, converts the arterice
and vencB hrancMales into ^^ aorta-bows," the A. pulmonalis is
given off from the posterior bow, and receives henceforth mixed
blood. In the Anura the origin is the same, but nearer the heart.
In CaeciliidaB it approaches the heart so far as to issue from the
extremity of the hulhus arteriosus, which is now divided by an
incomplete septum, one half conveying blood to the aorta-roots,
and the other to the A. pulmonalis. This septum was already
preceded by a longitudinal valve with free margin in the Anura !
As if to meet the coming event, a trace of ventricular septum ap-
pears at the apex within. There can now be no question of the
homology of the ventricles of the gar, and of the Cascilia. But
we have next the true Eeptilia. The hulhus arteriosus is split
externally, as it already was internally, but it is first represented
in most tortoises by an adherent portion, one half being the now,
to this point, independent arteria pulmonalis and the other the
nearly sjjlit aorta-roots. There can, I think, be little question of
the exactitude of the homology throughout.

It is no less certain that the salamander * fulfills in its devel-
opment the different stages to its permanent one, and is identical
in each stage, in respect to this point, with the orders it represents
at the time. This is true even of the long period during which
it bears the long branchial appendages and contained arteries and
veins which are not found in fishes ; it is then like the Protop-
terus, which has hyoid venous arches and appendages of those
arches at the same time. The tortoise f and Troj^idonotus I are
also identical in their successive stages with the types already

* Amblystoma. f Agassiz. X Rathke.

62 GENERAL EVOLUTION".

eniiinerated, the external or appendicular branchial vessels being
omitted, as belonging to the special serial deyelopment of the line
of air-breathing Anallantoidans. The division of the bulbus arte-
riosus into three instead of two may indicate a case of inexact
parallelism ; but, on the other hand, it may be that the pulmonary
partition is completed a little before the aorta-root partition, thus
passing through the batrachian permanent type. For explana-
tions of inexactitude see under Part II. No doubt the batrachian
type of hulhus arteriosus is passed by many serpents less extreme
and specialized than the Tropidonotus.

The aortic and pulmonary divisions of the bulbus in the Cae-
cilia are not laterally placed, but one is dorsal and the other ven-
tral, the one passing a little spirally to the right of the other. So
the pulmonary division of the bulbus turns over to the right in
the Anura. When the septum of the true reptiles appear, it rises
on the anterior wall of the ventricle till it is seen, in Eunectes, to
meet the partition between the arteria pulmo7ialis and aorta-roots^
and we have at once the right and left ventricles of the bird and
mammal structurally and functionally. Thus are the two ven-
tricles of man the same as the one ventricle of the fish, merely
divided by a septum.*

In the fissure of the aortic bulbus, in the reptiles, a spiral turn
is again given, and in Testudo the one aorta-root issues behind
the other. In the crocodile the turn is still greater, and the
right aorta-root issues to the left of the left root, and vice versa.
In the birds we have lost the left root, and parallelism ceases with
this change. In the Mammalia the right root turns to the left,
so that in the comparison of these classes the rule of von Baer
above quoted is true ; no mammal at present known is identical
in a foetal stage with any fully grown bird, but with a foetus of
the same, up to a certain point. But for both classes the joaral-
lelism of those below them holds true.

But it is with the exact parallelism or identity of genera that
we have to do in the present essay. That being established, the
inexact parallelism between the modern representatives of higher
groups follows by a process of reduction.

* Agassiz, I. c , denies the homology of the ventricles of the turtle and mammal;
but it appears to me erroneously. He says : " The fact that the great blood-vessels
{aorta and art. puhnonalis) start together from the cavum venosum seems to prove
that the two cavities in the heart of turtles, which are by no means very marked,
do not correspond to the two ventricles in Mammalia and birds."

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GENERAL EVOLUTION.

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74 GENERAL EVOLUTION.

6. TJie Extent of Parallelism.

Prof, de Serres and others have stated it as their belief that
the lower ^* branches" of the animal kingdom are identical with
the undeveloped forms of the higher ; i. e., that the mollusk and
articulate are not merely parallel with, but the same as the lower
conditions of, the vertebrate. The works of various embryologists,
as von Baer and Lereboullet, have shown this statement to be
erroneous, *^and founded on false and deceptive appearances."
The embryos of the four great branches of the animal kingdom
appear to be distinct in essential characters from their first
appearance. But Lereboullet, who, in his prize essay, has
compared with care the development of the trout, pike, and
perch of the Teleosts, with that of a Lacerta among reptiles, has
failed to point out characters by which the embryos of the two
vertebrate classes essentially differ, for a considerable period. It
is true that, as each and all of the species belong to widely differ-
ent generic series, parallelism is of the kind to be called inexact
or remote. But enough is known of embryology and paleontol-
ogy to render it extremely probable that the historic predecessors,
of the types whose embryology Lereboullet studied, formed a se-
ries of parallels of the kind termed in this essay exact.

Lereboullet states that a certain difference exists between the
eggs of the fishes and those of the Lacerta. This is for us merely
stating that the parents of the embryos differ, a fact which no one
will contest. The same may be said of the elevated or depressed
character of the surface of the vitellus on which the embryo re-
poses.

Secondly, after the appearance of the embryo the Lacerta is
furnished with the amnios and allantois ; the Teleost not. This
is certainly neither a generic, ordinal, nor class character of the
adult, for it is but temporary ; therefore, in generic, ordinal, and
class characters the embryos of the Teleost and Eeptile are still
identical. It is a physiological character, and not morphological,
and therefore far the less likely to be a permanent one, even in
embryos, under changed circumstances. The female of one of
the species of Trachycephalus inverts the skin of the back at one
season of the year to receive her eggs, because she can not lay
them in the water ; the other species of the genus do not. The
next genus in direct morj)hological line possesses a single species
whose female does the same for the same reason ; but the rela-

ON THE ORIGIN OF GENERA. 75

tions of these species and genera are zoologically the same as
though this modification did not occur. Many such instances will
occur to many naturalists. It is not pretended that they are as
important as the presence of the allantois ; but they constitute a
character, no doubt, similar in kind, and entirely at the service of
the needs of the great system of morphological succession. The
same may be said of the vascular area of the Reptile.

Lereboullet concludes his summary of the differences between
the Teleost and Reptile, up to the period of completion of the
heart, by saying, *^ It is easy to perceive that all these differences,
however imj)ortant they may appear, are constituted by the acces-
sory organs of the embryo, and do not modify the development of
the latter, which progresses in reality exactly as in the fishes."
He says the same previously, as to the relation of the same to the
bird and mammal.

We have, then, in the embryos of the lower vertebrates at a
certain time in the history of each, an ''exact parallelism''^ or
identity with the embryonic condition of the type which pro-
gresses to the next degree beyond it, and of all the other types
which progress successively to more distant extremes.

We have, however, so far, every reason to suppose that the
embryos of the other branches of animals never present an exact
parallelism with those of the Vertebrata.*

The embryo of the fish and that of the reptile and mammal
may be said to be generically, if not specifically, identical up
to the point where preparation for the aerial respiration of the
latter appears. They each take different lines at this point.
The fish diverges from the course of the reptile, and proceeds
to a different goal ; the shark does the same, but proceeds a
shorter distance ; while the Dermopter scarcely leaves the point
of departure. No doubt, there have been types which never
left this point and tvliose plan of circulatory system is identical
with that of the embryo reptile and mammal. Such a type was
only generically different from the reptile or mammal ivhich had
only taken the succeeding step, provided other structures were
not superadded.

By comparing the development of types of different classes in

* At about the time this was written the important papers of Haeckel on his
admirable Gastraea theory were published, but had not reached the author. Haeckel
shows the approximate identity of all the types of embryonic development. (Note,
1886.)

76 GENERAL EVOLUTION.

certain features whicli are only ordinal or generic in meaning, yery
erroneous conclusions may be reached by the inexact student as
to the want of parallelism of classes to each other. Thus Rathke
says of the development of the eye of the snake Tropidonotus, at
a certain period, that it is far in advance of that of the mammal
at the same stage. Here, says the objector, is a case where their
parallelisms do not coincide ; the mammal is really similar to a
younger stage of the reptile.

But, in fact, the size of the eye is but a generic or family char-
acter ; if the development of the lemur had been compared with
the snake, the mammal would have been found to be in advance ;
of the mole, much farther behind. If the snake selected were the
purblind Atractaspis, almost any mammal would have been in
advance ; if, on the other hand, the great-eyed Dii3sas, but few
Mammalia would have been parallel to it.

In a word, to find exact parallelism it is necessary to examine
the closest allies.

It is also of first importance to distinguish between the exist-
ence of generic or higher characters, and their condition under
various circumstances of individual life. If a foetal or larval
character be conserved through the adult life of a type, it will be
of course adapted to the functions of mature age. Thus the un-
developed character of the horns of the genus of deer, Rusa, are
not accompanied with the marks of individual youth of the cor-
responding stage of Cervus ; its individuals are fully grown and
functionally perfect. The species of Hyla are not small and in-
capable of self-preservation and reproduction, as is the corre-
sponding stage of Trachycephalus ; they are functionally devel-
oped. The student need not be surprised, then, if, when identity
or exact parallelism is asserted, he finds some differences depend-
ent on age and adaptation, for if he be an anatomist he need not
be informed that a morphological relation constitutes types what
they are, not a physiological.

II. OF KETARDATIOK AI^D ACCELEEATIOK 11^ GENERIC CHAE-

ACTEES.

First. Of adult metamorphosis :

The question has necessarily arisen, Have these remarkable
relations between genera resulted from an arrangement of distinct
generations according to a permanent scale of harmony, or have
the same genetic series of individuals been made to assume the

ON THE ORIGIN OF GENERA. 77

different positions at tlie same or different periods of the earth's
history.*

Prof. Marcel de Serres proposed the theory of repressions of
develojDment to account for the existence of the lower groups of
animals as 7iow existing^ an error easily exposed, as has been done
by Lereboullet in his yarious important embryological writings.
But little obseryation is sufficient to prove that a mammal is not
a shark where it has five gill-arches or aorta-bows, nor a batrachian
where it has three, or a reptile where it has the two aorta-roots.
This has been already sufficiently pointed out by von Baer, who
says there is " keine Eede " of such a theory as was afterward
proposed by de Serres. Thus are true the rules propounded by
this author, f 3. ^^Each embryo of a given animal type, instead
of passing through the other given animal found, diverges still
more from it." 4. ^^ In the basis, therefore, the embryo of a
higher animal type is never identical with an inferior type, but
with the embryo only of the latter."

I think that I have already made some progress in proving
that the near or true generic relationship is one of absolute devel-
opmental repression or advance. Paleontology shows that fami-
lies and orders, as now existing, were preceded in time by groups
which are synthetic or comprehensive, combining the common
characters of modern generic series. This process of synthesis
must, it is obvious, if continued, result in the near approximation
of the single representatives of the now numerous and diverse
groups. There is every reason to believe that a backward view
through time will show this to have prevailed throughout the

* Some naturalists seem to imagine that the demonstration of the existence of
intermediate types is only necessary to establish a developmental hypothesis. Thus
Dr. Dohrn (" Ann. Magaz. N. Hist.," 1868), writing of his discovery of that most
interesting genus, Eugereon, which combines characters of Neuroptera with those of
Hemiptera, does not hesitate to say that it proves the truth of Darwin's theory.
Now, it appears to me that a demonstration of the existence of a regularly graduated
succession of types, from the monad to man, would be only the minor of a syllogism
without its major, in evidence for development, so long as the proof of transition
of one step into another is wanting ; and the idea that such a discovery could estab-
lish a developmental theory is entirely unfounded. Indeed, the reasoning in which
some indulge— if we dare so call the spurious article— based on this premise alone,
is unworthy of science. The successional relation of types, though a most important
element in our argument, has been long known to many who give no sanction to
the idea of development.

f " Entwickclungsgeschichte," p. 224.

78 GENERAL EVOLUTION.

Vertebrata and other brandies, as we already can in part prove.
And I have no doubt that the synthetic types, which represent
modern orders, have existed in a generic relationship subordinate
to the plan of the synthetic class, and that the latter have existed
as genera only, of the type of the great branch. This is not ideal.
We only have to look to our extinct ganoids^ Archegosaurs, Laby-
rinthodonts, Compsognathus, Archseopteryx, Ornithorhynchus,
etc., to realize these facts.

The first genera then formed a scale of which tlie members
were identical with the undeveloped stages of the highest, and
each to each according to their position.

Such a series of antitypic groups having been thus established,
our present knowledge will only permit us to suppose that the
resulting and now existing kingdoms and classes of animals and
plants were conceived by the Creator according to a plan of his own,
according to his pleasure. That directions or lines of development
toward these ends were ordained, and certain laws applied for their
realization. That these laws are the before-mentioned law of re-
tardation AND ACCELERATION ; and law of NATURAL SELECTION.

The first consists in a continual crowding backward of the
successive steps of individual development, so that the j^eriod of
reproduction, while occurring periodically with the change of the
year, falls later and later in the life history of the species, confer-
ring upon its offspring features in advance of those possessed by
its predecessors, in the line already laid down partly by a prior
suppression on a higher platform, and partl}^, as above supposed,
by the special creative plan. This progressive crowding back of
stages is not, however, supposed to have progressed regularly. On
the contrary, in the development of all animals there are well-
known periods when the most important transitions are accom-
plished in an incredibly short space of time (as the passage of
man through the stages of the aorta-bows, and the production of
limbs in Batrachia anura) ; while other transitions occupy long
periods, and apparently little progress is made.

The rapid change is called metamorphosis ; the intervening
stages may be called larval or pupal. The most familiar examples
are those which come latest in life, and hence are most easily ob-
served, as in the insects and frogs. "When, during the substationary
period, the species reproduces, a constancy of type is the result ;
when the metamorphosis only appears at the period of reproduc-
tion, a protean type is the result ; when the metamorphosis is crowd-

ox THE ORIGIN OF GENERA. 79

ed back to an earlier period of life, then we have another persistent
type, but a new genus of a higher grade than its predecessor.

In reviewing many examples everywhere coming under the eye
of the naturalist, it is easy to perceive what would constitute a
plastic and what a conserved condition of generic, or even of spe-
cific form.

As one or more periods in the life of every species is character-
ized by a greater rapidity of development (or metamorphosis) than
the remainder, so in j^roportion to the approximation of such a
period to the epoch of maturity or reproduction, is the offspring
liable to variation. During the periods corresponding to those be-
tween the rapid metamorphoses the characters of the genus would
be preserved unaltered, though the period of change would be
ever approaching.

Hence the transformation of genera may have been rapid and
abrupt, and the intervening periods of persistency very long ; for
it is ever true that the macrocosm is a parallel or repetition of the
microcosm in matter and mind. As the develoj^ment of the in-
dividual, so the development of the genus. We may add : so the
development of the whole of organized beings.

These metamorphoses may be fitly compared to those in the
molecular constitution of matter. The force of cohesion between
the atoms of a vapor steadily increases with descending tempera-
ture, and in a regular ratio, till a given point is reached, when a
sudden metamorphosis to a denser or liquid condition takes place.
Nor have we reason to believe, with regard to many substances,
that there is any parallel relation between the temperature and the
molecular constitution before or after the metamorphosis takes
place. So, the temperature continuing to descend, the molecular
character of the liquid remains unchanged until, the vis conserva-
trix suddenly giving way at the ordained point, a soild is the re-
sult. Thus, while the change is really progressing, the external
features remain unchanged at other than those points, which may
be called expression-points.

Now, the expression-point of a new generic type is reached
when its appearance in the adult falls so far prior to the period of
reproduction as to transmit it to the offspring and to their de-
scendants, until another expression-point of progress be reached.

Thus a developmental succession does not so obliterate the lines
drawn around Nature's types as to render our system ineffectual
as an exDression of them.

GENERAL EVOLUTION.

The successional acceleration or retardation in metamorphosis
may be best illustrated in certain tailless batrachians, by the fol-
lowing tables. These are taken, it will be remembered, from the
Bufonidse and Hylidse as examples of '^ exact parallelism " ; three
are now added from the Eanidae and Discoglossidae. The case of
^' inexact parallelism " is that of the Scaphiopodidae.

Whether they are cases of acceleration or retardation can only
be determined by reference to the paleontology of the respective
groups, or a careful comparison of times of metamorphosis. In
the case of the Discoglossidae I suspect it to be retardation, as the
highest genus is extinct. The others I shall arrange with them
for temporary conyenieuce. Were I dealing with a group of Ga-
noids, I should imagine the process to be retardation, as this
group is going out of existence. On the other hand, were they
higher Oscine birds, we might imagine the case to be reversed.

Assumed,
140th gen.
120th gen.
100th gen.

80th gen.

60th gen.

40th gen.

20th gen.
1st gen.

Series No. 1. No. 2.

Bombinator. . .Hyla

Alytes *

No. 3.

.Epidalea.

e :

Discoglossus

Scy topis

e Pf : F

e Pf

F :

. . Buf o sp.

Osteocephalus. . .

e. Pf F

Ex :

. ,Bufo sp.

Pf : F

Ex t

Latonia Trachycephalus.

?F : Ex

. .Peltaphryne .

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Ixalus.

Rhacophorus,

Polypedates.

No vera, teeth.
Sometimes "
Always "

^ 2
§1

Points not attained.
Fig. 4.

* A parotoid gland of small size is added here, but is not generic as compared with Bom-
binator, as the latter has collections of crypts on the same region and over the body.

ON THE ORIGIN OF GENERA.

a OB

% 0

Pi
O

u
*

Death.

Eeprodiic-
tion.

Tail lost (re-
tard.).

Temp, roof
(ace).

Ossif. front
(ace).

Hatching.

Reproduce.
Prefrontals unit.

Ethmoid oss.
Tail lost.

Frontak 0B8i£

Hatched.

In the preceding diagrams each horizontal cohimn represents
the life history of the individuals of each genus. The line of
dots, stars, etc., represents the same developmental stage of each,
as it appears earlier or later in the life of the individuals. The
point of crossing the breeding period is that at which the charac-
ter is rendered permanent. When the change falls on this period
the character is not generic, as in Ixalus, Fig. 4. The period of
losing the tail, like that of breeding, is represented as occurring at
nearly the same time in the history of every genus, as it is gener-
6

82 GENERAL EVOLUTIOK

ally seasonal. Yet this is not always so, and, like the other char-
acters, has most likely had its period of shifting. Compare differ-
ence of time of development, for instance, of the frontal and pre-
frontal bones in Figs. 3 and 6. The comparison of the adult
stages of the less developed genera, at the tops of the columns,
with the larval conditions of those more fully developed, may be
traced in the absence of characters which appear in the latter. I
have convinced myself of the accuracy of the above relations by
the examination of many skeletons and wet preparations of adults
and larvae.

The diagrams* are representations of nature, and not ideal
sketches. It is to be noted as remarkable that the advance
throughout so many diverse groups is in the same direction, viz.,
to complete or excessive ossification of the cranium ; and this
identity of progress might be readily shown hy adding other char-
acters, were it not that the tables would become too complex for
convenience.

Has, any, such transition from genus to genus ever heen seen to
occur 9

It must of course take place during the life of the individuals
of a species, and probably at different times during the lives of
different individuals, dependent on their relative vigor. In our
view, ordinary metamorphosis is such a change, and we have
stated its bearing in this form, that ^' every character distinguish-
ing suborders, families, and genera is to be found among the indi-
viduals of some species, living or extinct, to mark new varieties
or stages of growth."

a. The Developmental Relation of Generic to Specific Characters.

For the relation of the law of retardation and acceleration to
specific characters we will look to development again. While the

* Notes on the diagrams : Fig. 4. Polypedates is here restricted to P. maeulatus
and P. quadrilineatus. The other species are referred to Rhacophorus, which has
not hitherto rested on any proper basis ; the asserted character — the palmation of
the hands — being one quite graduated from species to species among Hylas.
Chiromantis, Peters, is referred to the same, as its character is not strongly
marked and is visible in other species. For similar reasons Lcptomantis is referred
to Ixalus.

Fig. 6. In each of series ii and iii, two series are mingled for the sake of com-
paring the structures of the prefontal bones. Thus Heteroglossa, Staurois, Hylo-
rana and Trypheropsis are one series, and Hyperolius and Hylambates members of
another.

ON THE ORIGIN OF GENERA. §3

young of Trachycephalus are successively different genera, they
preserve most of their specifle characters so as not to be mistaken.
Agassiz says of the development of the North American turtles,*
" I do not know a turtle which does not exhibit marked specific
peculiarities long before its generic characters are fully devel-
oped." The same thing can be said of the characters of our sala-
manders, whose specific marks appear before their generic or even
family characters. I suspect that this will be found to be a uni-
versal law.

It also follows, if a developmental process, as proposed, has
existed, that at times the change of generic type has tahen place
more rapidly than that of specific,] and that one and the same
species {if origin he the definition) has, in the natural succession,
existed in more than one genus.

Apart from any question of origin, so soon as a species should
assume a new generic character it ceases, of course, to be specific-
ally the same as other individuals which have not assumed it. If
supposed distinctness of origin be, however, a test of specific
difference, we shall then have to contend with the paradox of the
same species belonging to two different genera at one and the
same time.

It follows, therefore, in our interpretation of nature, that
groups defined by coloration alone are not to be regarded as genera,
as is done by some ornithologists and entomologists. They are
simply groups of species in which distinctive generic characters
had not appeared up to the period of reproduction. Inasmuch
as in development certain specific characters appear first, among
them part or all of the coloration pattern, it is obvious that the
latter do not belong to the generic category. The employment of
such characters, then, in this sense, is only to commence reversing
the terms generic and specific, and to inaugurate the process of
regarding each species as type of a separate genus.

p. Of ProbaUe Cases of Transition.

Thus the transition between the toothed and edentulous con-
ditions in Cetacea takes place in the ordinary growth of the indi-
viduals of the genus Globiocephalus, and the transition between

* Gontrib. " N. Hist. United States," i, p. 391. Note.

f See " Proceedings Academy," Philadelphia, 1867, p. 86, where I observe that
genei'ic characters are probably less inherent than specific.

84 GENERAL EVOLUTION.

the ossified and non-ossified types of Chelonia occurs during the
life of the individuals of the genus Dermatemys.

But, in attempting to demonstrate this proposition, we must
bring forward facts of another kind. The anti-developmentalists
are accustomed to put such changes aside, as part of the necessary
history of established types ; hence we will not aj^peal to such.

1. The frog Ranula qffinis, of South America, was described
by Peters as probably a climatal variety of European Bana te7npo-
raria. In this he is supported by the fact that the specific char-
acters do not differ more than would characterize it as a local
variety, were it an inhabitant of Europe. But I have found that
it differs generically in the non-ossification of the ethmoid bone,
as has been confirmed by Steindachner, and represents an embry-
onic condition of the same bone in Eana. It is in fact an unde-
veloped Eana. That this is a true genus is confirmed by many
specimens, by additional species, and by the fact that the allied
genus Trypheropsis, embracing three species in the same region,
differs in the same way from the otherwise identical genus of the
Old World, Hylorana.

2. The South African Saurians, ChamcBsaura anguina and
Ma7icus macrolepis, are very closely allied in specific characters in
all respects, though distinct. They have one important ground
of generic distinction : the latter has one pair of limbs less than
the former. They are rudimental in Oham£esaura, and tlie disap-
pearance in Mancus is but another step in the same direction.
The difference in specific characters is of mucli less degree.

3. In the genus Oelestus there are numerous species, which
range from a slender snake-like form with weak limbs, to stouter,
strong-limbed forms with a more saurian build. Among these
the Haytian O. plioxinus is well distinguished by form and color-
ation. An allied genus from the same region is Panolopus, which
in specific characters approaches the C. plioxinus very closely,
much more so than any Oelestus (one species possibly excepted).
But in generic characters it is distinguished by the loss of all its
toes and the non-separation of nine plates on the end of the muz-
zle. The genus Diploglossus, on the other hand, occupying a
superior place on account of the division of the fronto-nasal into
three, is, in specific characters (of B. 7no7iotropis) much closer to
the stout Celesti than the species of the latter genus are among
themselves.

4. The Gronim nigrilahris is a Silurid, which in specific char-

OJT THE ORIGIN OF GENERA. §5

acters more nearly resembles the Amiurus lynx, than the latter
does the A. albidus and many other species of the genus. The
A. lynx is found in the same streams. The important generic
character, the absence of eyes, is, however, its constant feature
(in three specimens known to naturalists, others to fishermen).

5. The Cinclidium maximum, a large tree-toad of Brazil, re-
sembles in all its characters the Gentrotelma geograpMcum. The
specific differences between them amount to almost nothing, but
both sexes of the former grow larger and are furnished with a
generic peculiarity in the addition of some phalanges to the
thumb.

6. The Oporornis agilis, Baird, a North American bird of the
Tanager family, resembles very closely, in form, color, and habits,
the adjacent species of the adjacent genus Geothlypis. While its
specific characters are thus very close to Geothlypis teplirocotis,
it differs in the generic feature of a longer wing. By this it is
associated, and properly so, with another species 0. formosus,
which has the general color and habits of species of Myiodioctes
(if. canadensis), the next related genus.

7. The following fact I give on the authority of Prof. Leicly,
who will publish it in his forthcoming work on the extinct Mam-
malia of Nebraska, etc.

Three species of Oreodon occur in the Miocene strata ; they
are a larger, a medium, and a small sized species. In the Plio-
cene beds above them they are represented by three species of
Merychyus, which are in all respects known, identical specific-
ally with the three preceding. Each one may thus be said to be
more nearly allied to the species of the other genus than to its
fellow of the same genus, in specific characters. But each, on the
other hand, differs from each in generic characters. The teeth of
Merychyus are more prismatic, have longer crowns and shorter
roots, approaching the sheep, as Oreodon does the deer.*

* This phenomenon suggests an explanation on the score of adaptation, which the
other cases do not. The existence during the later period of a tougher material of
diet would increase the rapidity of wearing of the crown of the tooth, and require
a longer crown and greater rapidity of protrusion. This necessitates a dimi-
nution of the basal shoulder and shortening of the roots, producing the prismatic
form aforesaid. The deer browse on forest foliage, which is more tender, while
the Cavicornia graze the grasses, which contain, as is known, a greater amount of
silex ; hence the more rapid attrition of the tooth.

This may have been the case with the two extinct genera ; the different periods

QQ GENERAL EVOLUTION.

8. The Coreopsis discoidea T. and (r., var. anomala, Gray, is,
according to Mr. Aubrey Smith, much more nearly allied to Bid-
ens fro7idosa than to other species of its own genus, and the latter
is nearer to it than to other species of Bidens. It differs chiefly,
if not altogether, in the generic character : the barbs of the ache-
nia are directed upward ; those of the Bidens downward.

From these and many other such instances it may be derived :
That the nearest species of adjacent genera are more nearly allied
in specific characters than the most diverse species of the same
genus.

9. While Taxodium distichum and Glyptostrolus europcens,
conifers of North America and of Eastern Asia, respectively, are
readily distinguished by generic peculiarities of their cones, in
specific characters they appear to be identical.*

Confirmatory of this proposition is the statement of Parker : f
*^In tracing out the almost infinite varieties of the modifications
of any one specific type of shelled Rhizojood, my friend Prof.
Rupert Jones and I found that like varieties of distinct species are
much nearer in shape and appearance than unlike varieties of the
same essential species." (It is not unlikely that species should
here be read genus and variety species, though the latter may not
fulfill the requirements in regard to distinctiveness observed
among higher animals. In types like the Rhizopod, forms of this
grade may not be really differentiated. Their enormous geo-
graphical range would suggest this, if nothing else. )

Objection. — A class of objectors to the preceding explanation
of the relations in question will ascribe them to hybridization.
They have already done so to considerable extent among the
Teleosts (see the writings of von Siebold, Steindachner, and
Giinther). That hybrids exist in nature will be denied by none,
but that they are usual or abundant is not a probable condition of
a creation regulated by such order as ours is. The tendency to
modify in given lines of generic series, if admitted, will account
for many of the cases regarded as hybrids by the above authors,
for it is to be remarked in many cases how the generic characters

during which they lived may have seen a change from forest to praii'ie. (It is not
intended to suggest that the species of the two genera arc necessarily of the same
or any given number.)

* See Meehan, " Proc. Amer. Ass. Adv. Sci.," 1868. Newberry, " Ann. Lye,"
N. Y., 1868.

f " Transac. Zool. Soc.,'' London, 1864, p. 151.

ON THE ORIGIN OF GENERA. 37

are strikingly affected, and are chiefly used in guessing at tlie
parentage. This is among Cyprinidae so much the case that there
is scarcely an example of a hybrid between two species of the same
genus brought forward, but often between species of different
genera.

y. Ascertained Cases of Transition.

This naturally suggests that, in accordance with the theory of
acceleration and retardation, a transition can take place in the
life history of species. Have we any means of proving this sus-
picion ?

1. The genus Ameiva (Saurians of South America) has been
composed of species of moderate size furnished with acutely tri-
cuspid teeth. Teius, on the other hand, embraces very large spe-
cies with the molars obtusely rounded and of the grinding type.
These genera are generally held to be well founded at present. I
find, however, that in Ameiva pleii, which is the largest species of
the genus, in adults the greater part of the maxillary and mandib-
ular teeth lose their cusps, become rounded, then obtuse, and
finally like those of Teius. While young, they are true AmeivaB.
Strangely enough the A. pleii, from Porto Rico, acquires but
three such obtuse teeth when of the size of the other (St. Croix)
forms. In youth the teeth of all are as in other Ameivse. Here is
a case of transition from one genus to another in the same species.

2. In the important characters of the possession of branchiae,
of maxillary bones, and of ossified vertebrae, the tailed Batrachia
presents a series of a rising scale, measured by their successively
earlier assumption. Thus Salamandra atra^ produces living
young, w^hich have already lost the branchiae ; S. maculosa living
young with branchiae ; Plethodon f produces young from eggs
which bear branchiae but a short time, and do not use them func-
tionally ; Desmogantlms nigra uses them during a very short
aquatic life ; D, fusca and other Salamanders maintain them
longer ; while Spelerpes preserves them till full length is nearly
reached. Finally, species of Amblystoma reproduce while carry-
ing branchiae, thus transmitting this feature to their young as an
adult character. And it is a very significant fact that Spelerpes,
which bears branchiae longest, next to Amblystoma, is associated

* See Scbreiber's " Isis," 1833, p. 527; Koeliker, "Zeitschr. f. wissensch. Zoolo-
gie," ix, p. 464.

f Baird, " Iconographic Encyclopaedia " ; Wyman, Cope.

88 GENERAL EVOLUTION.

in the same zoological region with a genus (N'ecturus) which dif-
fers from its four-toed form (Batrachoseps*) in nothing more
than the possession of the osseous and branchial characters of its
larva, in a permanent and rej^roducing condition. That this is a
genus, to be one day converted into Batrachoseps by an accelera-
tion of its metamorphosis, or that has been derived from it by the
reverse process, I am much inclined to believe, f In supj^ort of
this I quote the following examination into the time of change of
the species of Amblystoma from my essay on that genus : J

*^ The great difference between the different species, and be-
tween individual species in this respect, may be illustrated by the
following comparison between the size of the animals at the time
of losing the branchiae, so far as known, and that to which they
ultimately attain.

Species. Size at loss of branchi^.

In. Lines.

A. jeffersonianum, 1 S'YS

A. punctatum, 1 10

A. conspersum, 1 10"5

A. opacum, 2 2

A. texense, 2 1

A. microstomum, 2 3'5

A. talpoideum, 3 (perhaps too large).

A. paroticum, 3 7*5 (not smallest).

.... { S 1 to

A. tigrinum, j ^ ^

A ^' i 3 9-5 to 8 9

A. mavortium, ■] s 0

A. mexicanum, ? branchias persistent. 8 "

The last species, though not uncommon in collections, is not
known to pass through its metamorphoses in its native country,
but reproduces as a larva, and is therefore tj^DC of the genus Sire-
don of Wagler, Cuvier, Owen, and others. The larva of A. ?na-
vortium in like manner reproduces, but their offspring have in
the Jardin des Plantes and at Yale College undergone an early
metamorphosis.*

ERAG]

E FULL SIZE.

In.

Lines.

6-1

7-5

9-5

7-2

2-5

8 to 10

* See Cope, *' Jour. Ac. Nat. Sci.," Phila., 1866.

f Necturus differs from all true Salamanders in the possession of the os interca-
lare of the skull; the parallelism is therefore inexact. (Note, 1886.)
X " Proceed. Academy," Phila., 1867.

* Through the kindness of Prof. Dumeril I have received both larvae and
adult of the species here noted, and observed by him. The larva is, as he states,
Siredon lichenoides of Baird, while the adult is his Amhlyntoma mavortium^ not A.
tigriyium { = luridum), as also supposed by Dumeril. (Note, 1886. I now believe
these forms to belong to one species.)

. ON THE ORIGIN OF GENERA. §9

Here is a case where all the species but two change their
generic characters ; one changes them or not, according to cir-
cnmstances, and one does not change them at all. What are the
probabilities respecting the change in the first set of species ?

As we know from the experiments of Hogg, Dumeril, and
others that metamorphosis is greatly hastened or delayed by the
conditions of temperature and light, what would not be the effect
on such a protean species of a change of topographical situation,
such as the elevation or depression of the land ? And I liaye no
hesitation in saying that if the peculiarities of series of individuals
of A. tigrinum and A. mavortmm, in the respects above enumer-
ated, were permanent, they would characterize those series as spe-
cies, as completely as any that zoologists are accustomed to recog-
nize. For the evidences on this head, see the discussions of those
species in my monograph.

The experimxcnts of Hogg, above alluded to, are as follows, as
given by him in the "Annals and Magazine of Natural History."

He placed a number of impregnated ova of frogs in vessels
arranged at regular distances from the light, in a cave. The les-
sening degrees of light were of course accompanied by a corre-
sponding but much less rapid decline in temperature. The result-
ing effects on the metamorphosis may be tabulated as follows :

310.

day.

60°

56°

53°

51°

Ecrg.

Egg.

Larva free,

Larva free.

Larva very large,

Metam. complete.

Larva large,

Larva large.

Larva small.

Metam. complete,

Metam. complt.

■se-

Metam. comp.

3. The reproduction of some sj^ecies of insects before they
complete their metamorphosis is a well-known fact, and it is par-
ticularly to the point that, in many of them, some individuals do
attain to their full development, while the many do not. West-
wood says,* "Two British species of this family (the Reduviidae),
Prostemma guttula and Cor anus siibapterus, are interesting on
account of their being generally found in an undeveloped state,
the latter being either entirely apterous or with the fore-wings
rudimental, although occasionally met with having the fore-wings

* Uhler informs me that Amyot's asserted color characters are not reliable.

90 GENERAL EVOLUTIOK

completely developed." ''I think," says Spinola, "that the pres-
ence of wings and their development depends on the climate" ; and,
in speaking of Oncocephalus griseus, he says, " The influence of
the northern climate appears to have arrested the development of
the organs of flight. It will be seen that I have referred else-
where that I have noticed that it is especially in hot seasons that
certain species acquire wings, while the circumstance noticed re-
specting the ordinary occurrence of winged specimens of Micro-
coelia in the West Indies is confirmatory of the same opinion."

4. It is now known that certain Orthoptera do not get through
their metamorphosis in time for the period of reproduction, and
hence never, or in rare instances only, develop more than a short
distance beyond the pupa state.

5. My friend P. R. Uhler tells me of an example among
Hemiptera of the genus Velia. The species V. rivulorum, Fab.,
and V. curreiis,^ of Europe, are only distinguished by the devel-
opmental feature of the presence of wings in one, and their ab-
sence in the other. Another species of the tropical region of the
West Indies, Halobates americanus, Uhler, is furnished with
wings, while its individuals, which occur abundantly in North
America, have been generally supposed to lack them. Individuals,
however, no doubt occur whose development is so far accelerated
as to permit them to acquire wings before the period of rej^roduc-
tion, since one such has been found by Uhler.

These wing characters are in many cases generic, it aj^pears to
the writer ; and the fact that they differ, without corresponding
specific differences, is important evidence as to the origin of the
genera.

6. The females of the Lepidopterous genus Thyridopteryx
never develop beyond the pupa state, according to the same au-
thority, before reproduction ; they are reproducing pupae, so far
as the external characters concerned in metamorphosis go. In
other words, the latter have been retarded, while the reproductive
system and others have progressed. Now, generic characters are
seen in the first, not in the last. The influence of the males is
sufficient to prevent more than a part of the offspring from being
retarded in the same manner.

I have selected a few of this class of facts which have come
before my mind during the present writing, as drawn mainly from

* On " Insects," ii, p. 493,

ON" THE ORIGIN OF GENERA. 91

my own experience. How many more of the same purport could
be found by search through the great literature of science, or in
the field of nature, may be readily imagined. I have no doubt
that the field of entomology especially will furnish a great number
of evidences of the theory of acceleration and retardation, espe-
cially among the insects with active pupa3.

Finally, having already stated the law according to which these
processes naturally take place, I quote the following significant
language of Hyatt in the above quoted essay on the Cephalopoda,
as approaching nearer to the ^Maw of acceleration and retarda-
tion " than anything I have found written. He says :

'^'^In other words, there is an increasing concentration of the
adult characteristics of lower species, in the young of higher sjoe-
cies, and a consequent displacement of other embryonic features,
which had themselves, also, previously belonged to the adult peri-
ods of still lower forms."

The preceding propositions have been formulated as follows, a
few additions being now made :

I. That genera form series indicated by successional differences
of structural character, so that one extreme of such series is very
different from the other, by the regular addition or subtraction
of characters, step by step.*

II. That one extreme of such series is a more generalized type,
nearly approaching in characters the corresponding extreme of
other series.

III. That the other extreme of such series is excessively modi-
fied and specialized, and so diverging from all other forms as to
admit of no type of form beyond it. f

IV. That the peculiarities presented by such extremes are
either only in part or not at all of the nature of adaptations to the
external life of the type. J;

V. That rudimental organs are undeveloped or degraded con-
ditions of the respective characters developed or obliterated in the
extreme of the series.

VI. That the differences between genera of the same natural
series are only in the single modifications of those characters which
characterize the extreme of that series.

* St. Hilaire, Owen, Agassiz, Dumeril.
f Dana on " Cephalization " ; Leconte.

X Owen on " Cetacea," " Trans. Zool. Soc," London, 1866, p. 44. Leconte on
" Carabidae," " Trans. Amer. Philos. Soc.," 1853, p. 364.

92 GENEEAL EYOLUTIOK

VII. That the relations of the genera of a primary series are
those of the different steps in the development of the individuals
of the extreme genus ab ovo {von Baer^ Agassiz) (with sometimes
the addition of special adaptive features ?).

VIII. That the presence, rudimental condition, or absence of
a given generic character can be accounted for on the hypothesis
of a greater rapidity of development in the individuals of the spe-
cies of the extreme type, such stimulus being more and more vig-
orous in the individuals of the types as we advance toward the
same, or by a reversed imj^ulse of development, where the extreme
is characterized by absence or "mutilation" of characters.

IX. And that, as the character of the genus at the period of
reproduction of its species is that which is per^^etuated ;

- X. So the character of the genus has been first inferior, then
protean, and then advanced, as the metamorphosis has been by a
retrograde movement in time, posterior to, at, or anterior to the
period of reproduction.

XI. That it therefore results that there is one primary struct-
ural type involved in such a series of species, which is made to
present, at any given j)eriod in its geologic history, that appearance
of succession of genera ordained by Creative Power.

d. On the Origin of Inexact Parallelism.

The hypothesis can only be demonstrated in case of exact par-
allelism. If proved in these, it readily accounts for the cases of
inexact parallelism, which are of course in any single period vastly
in the majority. First take the case of simple inexact parallel-
ism. A series of individ uals of the genus Didocus undergo the
metamorphosis of the cranial structure earlier and earlier in life,
commencing by completing the ossification of the membrane of
the fronto-parietal region in full age, until at last it becomes com-
13leted as early as the period of reproduction. Heretofore the
adult offspring have appeared during a long period, invariably
characterized by the larval cranium ; but like now producing like,
this development springs into new power, and the offspring ossify
the cranial bones far earlier than their immediate predecessors ;
in a word, the genus Pelobates has been created ! At this state of
progress Didocus is an undeveloped Pelobates.

Let us, however, suppose the '^acceleration " of development
of the cranial bones still to progress. The character appears now
soon after the ordinary metamorphosis has been passed, and now

ON" THE ORIGIN OF GENERA. 93

a little before. The identity of Diclocus with the undeveloped
Pelobates is thereupon lost !

So may have been the relations between Pelobates and Cul-
tripes. Pelobates was probably once identical with the undevel-
oped Cultripes ; but the same acceleration has concentrated the
characters more rapidly than the other larval stages, leaving Pelo-
bates behind.

This I conceive to be the explanation of this relation : when
the parallelism is inexact by two steps, as in Spea to Didocus, by
the obliterated ear and ossified xiphisternum. The continued
concentration of characters has been carried to earlier stages till
the identity exists in the adult state of neither one, but at a pe-
riod of larval life of botli, shortly preceding the adult period of
the lower. The relations between the Amblystomidae and Pletho-
dontidaB, which I have elsewhere * pointed out, have probably
had their origin in this way.

If we attempt to ]3rove the identity of the modern Mammalian
foetal circulation with that of the modern adult fish, we may find
nearly an exact parallel in this respect, as it is the basis of class
distinction ; but in other respects the identity will not exist, ren-
dering the parallel inexact or remote. The structure of the ori-
gins of the aorta is at one time identical with that of the shark,
with one exception : in the former but four aorta-bows appear to-
gether ; in the latter five. In the former the first disappears as
the fifth comes into being. This is simply a continuation of ac-
celeration. The first generalized representative of the Mammalia
lost the first aorta-bow toward the latter part of its growth, and
became the next genus in advance of the selachian. The fact
that these bows do not appear exactly simultaneously, but rather
successively, renders it necessary that in a regularly shortening
period of possession of transitory characters, one such, as the ex-
istence of the first aorta-root, should vanish before the appearance
of a permanent, the fifth, in the more specialized types, where
acceleration reaches its maximum. This is indicated by the fact
that in the Batrachia, where the acceleration has not attained so
high a degree, the first and fifth aorta-bows co-exist for some time,
though the first and second disappear before maturity.

So also with the splitting of the bulbus arteriosus. As in the
Batrachia, the pulmonary ductus communis only is to be sepa-

* "Jour. Ac. Nat. Sci.," Phil., 1866, p. 100.

94: GENERAL EVOLUTION.

rated ; the remaining bulbus is divided by a long valve or incom-
plete septum, tracing the division of the aorta-roots. In the ser-
pent (Rathke) this division is so accelerated as to appear at nearly
the same time as the septum of the pulmonary duct. In the
mammal, on the other hand, while the division of the aorta-root
takes place as soon as in the last, the pulmonary seiDtum is accel-
erated so as to appear long before the first named. Hence, in the
septa in the serpent, the singular anomaly seems to present of
the mammal passing through the Batrachian stage, while the ser-
pent, a nearer relative, does not.* If, however, we take the less
typical serpent, we will find the aortic septum to appear a little
later, thus giving the Batrachian type, and if we reverse the order
of time, so that the succession becomes one of retardations, we
wdll find the same known ratio will bring us to an identity under
all circumstances.

This, then, is the explanation of the divergence and want of
** exact parallelism," which is observed in comparing the develop-
mental histories of all tjipes not 7nost closely allied. It has not,
according to our theory, always been a divergence, but was at a
prior epoch in each case a relation of "exact parallelism," the
lower type a rej^ressed higher ; the former identical with one of
the stages of the latter. But the process which has produced this
relation, continued, has of necessity destroyed it, so that the ex-
act parallelism has always been a temporary relation, and one
shifting over the face of the system.

III. OF HIGHER GROUPS.

First. Comparison of the contemporary.

Having now admitted a developmental succession of genera,
and, second, that this has progressed more rapidly at certain times
in the earth's history than any modification of specific forms, the
hypothesis already broached naturally comes up : Has such trans-
formation of types, generic or higher, tahen place in any degree
simultaneously, throughout a great number of species 9 An af-
firmative answer to such a proposition is absolutely necessary to
its acceptance as expressing the phenomena exhibited by geolog-
ical succession of types. Let us try to answer the question put in
a closer form. Have the same species been transferred from one

* This is the way indeed in which it is stated by Rathke, " Entwickelungsge-
schichte der Natter," p. 164.

ON THE ORIGm OF GENERA. 95

geologic epoch to another by a change of generic form ; and has
not the genus been transferred from one epoch to another under
change of ordinal type, and as a consequence the same species ?

As a reply I propose to render the affirmative of the first of
these questions highly probable.

Paleontology only will be able to answer this question conclu-
sively, though, as we have abundant evidence that the relations of
species to genera and other higher groups were the same then as
now, we may look to the present status as furnishing important
evidence on the subject. We are turned at once to the probable
history of development in the separate zoological areas of the
earth's surface. The question may be asked, Are the present zo-
ological regions on an equal plane as to the geologic relations of
their faunae, or are they related as the different subdivisions of a
geologic period in time ?

I have on a former occasion asserted that the latter of these
propositions was true.*

a. Of Homologous Groups.

Naturally following the admission of a developmental succes-
sion of organic beings is the question of its relation to the differ-
ent surfaces of land and water on the earth. The following con-
siderations bear on this subject.

Among the higher groups of animals can be detected series
^* homologous " on the same principle as the alcohols (? com-
pound radicals) and their derivatives ; and the component types
of each can be, and have been in many instances, shown to be
''heterologous," as are the ethers, mercaptans, aldehydes, acids,
etc. Among Mammalia two partly homologous series have been
pointed out, Implacentialia and Placentialia ; possibly such are
the types Altrices and Prgecoces among Aves ; of a lesser grade
in this class are the parallel series of Pullastrae and Gallinae, of
Clamatores and Oscines. Among tortoises I have alluded to the
Pleurodira as compared with the remainder of the order, already
parallelized by Wagler ; and, of lesser grades, the series among
Lacertilia of Acrodonta and Iguania, parallelized by Dumeril and
Bibron, and of Teidae and Lacertidae, compared by Wiegmann. I
have discovered a full parallelism between the Raniform and Arcif-
erous Anura. It is carried out between the Characini and a group of
remaining Physostomous Fishes, perhaps not yet well defined ; it

^ On " Arciferous Anura," " Journ. Ac. Nat. Sci.," 1866, p. 108.

96 GENERAL EVOLUTION.

is exhibited between tlie orders Diptera and Ilymenoptera among
insects. None of these comparisons can be allowed, of course,
without the most searching anatomical and embryological analysis.

This heterology i^ what Swainson and others called ''^analogy"
as distinguished from affinity. It generally relates genera of dif-
ferent zoological regions. Mimetic analogy, on the contrary, re-
lates genera of the same region ; it is a superficial imitation which
has occurred to critical biologists, and is of much interest, though
as yet but little investigated. It has as yet been observed in ex-
ternal characters only, but occurs in internal also ; it has been
accounted for in the first case by the supposed immunity from
enemies arising from resemblance to wxll-defeuded types. No
such explanation will, however, answer in the latter case. I be-
lieve such coincidences express merely the developmental type
common to many heterologous series of a given zoological ** re-
gion " ; this will be alluded to a few pages later.

We naturally inquire. Is there anything in the food, the vege-
tation, or the temiDcrature to account for this aj^parent diversity
in the different regions ? Are there not carnivora, herbivora,
seed-eaters, insectivores, and tree-climbers, where game and grass,
seeds and insects and forests grow the world over ? We answer
undoubtedly there are, and these adaptations to food and climate
are indeed as nothing in the general plan of creation, for every
type of every age has performed these functions successively.

3. Of Heterology.^

This relation will be exhibited by a few examples from groups

known to the writer, commencing with the Batrachia anura.

Raniformes. Arciferi.

External metatarsal free.

Aquatic. Rana. Pseudis.

Metatars. shovel, Hoplobatrachus. Mixophyes.

External metatarsal attached.

Feet webbed.
Metatars. shovel. Pyxicephalus. Tomopterna.

* Some of the cases below cited as heteroloiry I believe to be trulv of this char-
acter ; but some others are probably not such, but are merely series of genera pre-
senting similar structural peculiarities as consequences of the operation of identical
laws. I would place under this head, and withdraw from the homologous class, the
families of Lacertilia Leptoglossa, Diploglossa^ and Typhlophthalmi^ those of the Old
and New "World Quadrumana and those of Cephalopoda. These distinct modes of
origin of corresponding forms have been recently termed, by Lancaster, homogeny
in the ease of homologous groups, and homoplassy when the imitative types are on
distinct lines. (Ed. 1886.)

PLATE n.

PLATE II.

Figures of Lizards of the family Iguatiidfe to be compared with a homologous
series of Agamidae represented in Plate Ila. The species are :

Fig. 1. Basiliscus phimifrons Cope, Costa Rica. From Cope.

Fig. 2. Iguana tuhercidata Linn., South America. From the " Standard Xatural
History."

Fig. 3. Crotaphytus wislizeni B. G., Sonoran Region of North America. From
Baird.

Fig. 4. Phy maiurus pallumaGTSLV., ChWi. From Bell.

Fig. 5. Fhrynosoma cornutum Harl., Texas. From " Standard Natural History."

PLATE Ila.

Figures of Lizards of the family Agamidae which form a homologous series with
the Iguanidse represented on Plate 11.

Fig. 1. Lophura arnboinetisis Schloss., Amboina. From "Wagler.

Fig. 2. Physignathus mentager Giinther, Siam. From Giinther.

Fig. 3. Liolepis hellii Gray, China. From Dumeril and Bibron.

Fig. 4. Uromasiix spinipes Cuv., Arabia. From Guerin.

Fig. 5. Moloch horridus Gray, Austi-alia. From " Standard Natural History."

ON THE OKIGIN^ OF GENERA.

Raniformes.

Arciferi.

Arboreal ; vom. teeth.
Subarboreal.

Leptopelis.
Hyperolius.
Hylambates,

Hvla.

Hylella.

Nototrema.

Terrestrial.

" spurred,

Feet not webbed.
Cassina.
Hemimantis.

Cystignathus.
Gomphobates.

Comparmg the genera in a general physiological sense, we may
parallelize further.

Aquatic, with digital dilatations.

Heteroglossa,

Arboreal : cranium hy- ) -r, , , ^

perostosed. \ ^oljved^tes.

" cranium free. Rhacophorus.

Acris.

Trachycephalus.

j Hyla.

( Agalychnis.

The same kind of parallels exists between the primary groups
of the Testudinata, as follows :

Crtptodira. Plefrodira.

Five complete pairs of bones across the plastron.

Pleurosternidae. Stemothseridae.

Four pairs of bones across plastron ; not more than two phalanges on all toes.

Testudinidae. Pelomedusidae.

Three phalanges on most digits ;
Zygomatic arch ; no parieto-mastoid.

Eraydidae. Podocneraididae,

Temporal fossa over-roofed hj parietal.

Macrochelys. Podocnemis.

No zygoma ; a parieto-mastoid arch.

Hydraspididae.

If we compare the peculiarities of generic structure merely
with reference to their adaptation to the animals' habits, we will
see the following :

Cryptodira.
Feet reduced for terrestrial progress.

Testudinidae.
Feet normal.

Anterior lobe of sternum movable.

Cistudo.
Cinosternum.
Anterior lobe fixed.
Neck very elongate.

Trionychidae.
Neck shorter ; aquatic.
Temporal fossa open.

Emydidae in gen.
Temporal fossa over-roofed.

Cheloniidae.

Pleurodira.
Pelomedusidae.

Sternothaerus.

Chelodina.

Hydraspididae.
Podocnemis.

The parallels between the genera of the American Iguanidae
and the Old World Agamidae are similarly quite close. They are
shown on Plates II and II a.
1

GENERAL EVOLUTION.

Abdominal ribs.

Iguanidje.
Polvchrus.

AGAMIDiE.

No abdominal ribs.

llibs greatly prolonged into a lateral wing.

* * Draco.

Ribs not prolonged.

Arboreal types, generally compressed.

A dorsal and caudal fin supported by bony rays.

Basiliscus (no lem. pores). Lophura (pores).

No vertebral fin.

No femora] pores.
Form slender, scales in Calotes.

equal series. Bronchocc

Form elongate ; eyebrows

Gonyocephalus.

cela. )

Lasmanctus.

elevated, tail compressed.
Form stouter, scales less

regular.

Hypsibates.

Femoral pores.

Brachylophus.

Ophryoessa.
Tiaris.

Diporophora.

Pliysignathus.
* *

Low crested; small hyoid

disk.
High crested; large hyoid

disk. Iguana.

Tail with spinous whorls. Cyelura.

Terrestrial types of flattened form.

Femoral pores.
Tail with whorls of spiny

scales. Hoplocercus. Uromastix.

Tail long, simple; scales

small. Crotaphytus. Liolepis.

Tail simple, scales large. Sceloporus. * *

No femoral pores ; preanal pores.

Tail with whorls of spines. * * Stellio.

Tail simple, not elongate,

ear open. Proctotretus. Agama.

Neither femoral nor anal pores.

Much flattened, tail short, scales irregular.

Ear exposed. Phrynosoma. Moloch.

Ear concealed. (Doliosaurus, s. g.) j Segd'Sus!'"''

A similar parallel may be drawn between the American Teidas,
and the Old World Lacertidae, and in fact between all the families
of the Lacertilia Leptoglossa. I have added to these for compari-
son two families of the Typhlophthalmi. Each family embraces
one or more series, and these exhibit a remarkable similarity in
the relative development of the limbs and digits ; among the
higher groups the parallelisms lie in the arrangement — as greater
or less separation — of the head shields. The Scincidae are cosmopo-
lite ; the Gymnophthalmidae, which have the eyelids of their foe-
tus, are Australian ; the Sepsidas, either larval or senile in head
shields, are mostly Ethiopian.

ON THE ORIGIN" OF GENERA.

^ a.

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'til

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Ilerpetosaura.

Acontias.

Typhlosaurus.

P'eylinia.

Anelytropsia.

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100 GENERAL EVOLUTION.

The first comparison of these groups was made by Wiegmann
(Herpetologia Mexicana), who employed, however, only the Scin-
cidse and Lacertidae, and could not include the many types made
known since his day.

From the class Aves I have selected only the homologous series
of the Clanatorial and Oscine Passeres. Naturalists more fully
acquainted with the genera could probably increase the examples
of heterology largely. Each group furnishes us with carnivo-
rous, insectivorous, and frugivorous forms ; each with walkers,
climbers, and sedentary genera ; each with butcher-birds, thrushes,
warblers (not in song !), wrens, and fly-catchers. Each and all of
these types are teleologically necessary to any country complete in
the wealth of nature, and to each geological period.

Clamatores. Oscines.

I. Tree-climbers, with long hind toe and tail feathers stiffened and acute.

Dendrocolaptidce. Certliiidce.

II. Terrestrial in part, with the tertials as long as the primary quills.

Geobatidce. ITotacillidce.

III. Tree-perchcrs with hooked bill, graduating from powerful to medium and
slender.

JPbrmicariidce Turdidce.

Thamnophilus. Bill strongest, hooked. Lnnius.

Formicarius. " moderate. Turdus.

Formicivora. " weak. iSylvia.

Rhamphoccemus. " slender (wrens). Troglodytes.

IV. Fly-catchers with flat bill and weak legs ; wait for their prey and take it on
the wing.

Tyrannidve. Muscicapa et aff.

V. Flat-billed berry and fruit eaters.

Cotingidce. Bomhycillidce.

From the Mammalia the well-known series of the Marsupialia and Placentialia
may be chosen.

Placentialia. Marsupialia.

I. Toes unguiculate, in normal number ; sectorial teeth ; i. e., one or more molars
with one or no internal tubercles ; canines strong :

Carnivora. Sarcophaga.

I. Digitigrade.
Toes 5 — 1.

True molars § (upper incisors more numerous in some).
Amphicyon. Thylacinus.

II. Plantigrade ; molars tubercular.
a. Posterior molars f .

* * Dasyuridae.

aa. Posterior molars |.
Ursidffi. * *

II, Toes unguiculate ; molars with more than one row of pointed tubercles ; canines
weak or none ; incisors large.

ON TEE ORIGIN OF GEKERA.

101

Insedivora.

Gymnura.
Cladobates.

a. Tubercular molars |, toes 4 — 5.
Tail naked.

Tail hairy.

Entomophaga.

Didelpbys.
Myoietis

rV. Molars with transverse crests, no canines ; tusk-like incisors ; pairs of limbs of
similar proportions.

Froboscidia. Diprotodontidfe.

Two inferior incisors ; molars with two cross-crests ; size huge.
a. Two rudimental lateral incisors above.

* * Diprotodon.

aa. ? One pair of incisors only above ; a trunk.
Dinotherium.

Y. No canines ; two pairs of cutting incisors.

«. Three true molars.
Rodentia. * *

aa. Four true molars.

* * Rkizophaga.

The parallels are in this case very imperfect in details, and but
few worthy of the name can be made. They are, however, illus-
trative of a remote heterology, sufficiently remarkable to have
claimed the notice of naturalists for many years. "^ I also have
little doubt but that future paleontological discoveries will in-
crease the number of parallels, f and bring to light truly heterolo-
gous generic terms of the Marsupial series. Predictions of this
kind have been on many occasions fulfilled (e. g., some of D'Or-
bigny's among the Cephalopoda), and I look with confidence to
the ultimate demonstration of that heterology here which has
been already seen in the Batrachia and Reptilia.

The homologous groups of the Catarrhine and Platyrrhine
Quadrumana are measured as follows :

CatarrJiini.

Platyrrhini.

Tailless.

Andropithecus.

Simla.

Hylobates.

Tail short.

Cynocephalus.

Macacus.

Brachyurus.

Long tail.

Thumb developed.

Cercopithecus.

Lagothrix.

Mycetes.

Thumb rudimental.

Semnopithecus.

Brachyteles.

Thumb none.

Colobus.

Ateles.

* We owe very many observations on the Marsupials to Owen.

f The extinct carnivorous family of the Nimravidae which forms a homologous
series with the cats (Felidae) was discovered by the writer some years after this was
written. (Ed. 1886.)

102 GENERAL EVOLUTION".

I append two homologous series, represented by the Nautilea
and the Ammonites of the Tetrabranchiate Cephalopoda, which
are distinguished, the first by the simple septa and the siphon
central or marginal ventral ; and the second by the complex and
folded septa and siphon central or marginal dorsal. The parallel-
isms have been noted by Barrande, Bronn, and many concholo-
gisfcs, who can furnish a much more full table than the following,
from the most recent sources :

Nautili. Ammonites.

A. The shell straight, unwound.

Orthoceras. Baculites.

B. The shell more or less curved or wound,
c. Simply curved.

Cyrtoceras, ) Toxoceras.

Phragmoceras, )

aa. A more or less straight portion, folded on the remainder.
j3. Folded poition in close contact with remainder.
Ascoceras. Ptychoceras.

/3/3. Folded portions not in contact.
V ? Hamites.

aaa. One extremity spirally wound, the volutions not in contact.
/?. Extremity of the shell prolonged beyond the wound portion.
Lituites. Ancyloceras.

)8/3. Extremity not prolonged in a line.
7 The spiral flat.
Gyroceras. Crioceras.

yy. The spiral elevated (heliciform),
Trochoeerus. Turrilites.

aaaa. Spiral turns of the shell in contact.

p. Er.tremity prolonged in line beyond the spiral.
* * Scaphites.

)S/3. Extremity not prolonged beyond spiral.
Nautilus. Amrhonites.

We may now consider the question of the origin of these higher
groups. In the first place, we must lay down the proposition that
the characters which constitute groups '' higher ''^ iii the compari-
son of ranh (we do not of course mean higher in the same line, as
we say higher genus in a family, or higher order in a class) are
such solely from their bei7ig more comprehensivs, or i^esent
throughout a greater range of species.

What is true, therefore, in respect to characters of genera, is
likely to be true in respect to characters of higher groups, such
as we have been considering in the preceding pages. Believing,
then, that a new genus has been established by the transition of a
number of species of a preceding genus in-order, without neces-
sary loss of specific characters, I think the same process may have
established the suborders and orders in question. That is, that a
large numiber of genera have near the same time, in past or pres-

01^ THE ORIGIN- OF GENERA. 103

cnt geological Idstory, passed into another suborder or order hii
the assumption or loss of the character or characters of that to
or from luhich they ivere transferred, and that without necessary
loss of their generic characters.

I will cite a probable case of this kind, the facts of which I
have already adduced.

It has been shown above that the genera of six of the fami-
lies of the Batrachia anura form series characterized by the suc-
cessive stages of ossification of the skull, terminating in a der-
moossified condition, with over-roofed temporal fossae. That in
nearly all the other families similar relations between genera exist,
but are nowhere carried so far. The character attained by all
the first series is now only generic ; but should all the genera of
each of the six families assume this character in time, as is neces-
sary in accordance with a development hypothesis, it would at
once possess a new and higher importance, and would become or-
dinal or otherwise superior. It would define a series homologous
with all those types which had not attained it. This character
of the over-roofing of the temporal fossae has actually attained a
family significance among the Testudinata — e. g., as defining the
marine turtles ; and similar characters are found by Owen to
characterize the Labyrinthodontian order of Batrachia.*

Agassiz has pointed out a similar and more extended case, in
the lieterocercal and Homocercal ganoids. Had we not so many
of the closest approximations between members of these groups,
they would stand in the systems as two great homologous series,
with their contained heterologous genera. As it is, these heter-
ologous terms or genera are evidently so nearly allied that Agassiz,
in the " Poissons Fossiles," has thought it best to arrange the latter
together, thus instituting a system transverse, as it were, to the
other. This may be necessary, since Kolliker points out transi-
tional forms, and perhaps certain types may have begun to aban-
don the heterocercal form near the period of reproduction, pro-
ducing offspring somewhat protean in character, preparatory to
an earlier appearance and consequent permanence of the homocer-
cal type. This is to be derived from the history of the metamor-
phosis of Amblystoma.

In the same manner the development of the convolutions of the
brain does not define groups of the highest rank, since it pro-

* The roof here alluded to by Owen includes some two distinct bones not known
in the arch of the Anura, and therefore different.

104 GENERAL EVOLUTION.

gresses chiefly during the later periods of embryonic life, and is
therefore a '^developmental character." Owen has endeavored to
distinguish the primary divisions of Mammalia by the character
of these convolutions, whereas they really define only the sub-
groups of the orders. Eor we have Lissencej^halous (smooth-
brained) monkeys — certain lemurs — and smooth-brained Eumi-
nants — i. e., the extinct Brachyodon and Anoplotherium, accord-
ing to Lartet and Gratiolet. The lowest types of the existing
smooth-brained Mammalia, including es^^ecially those wdth no
or rudimental corpus callosum, the Marsupials, are also distin-
guished by the non-development of the deciduous teeth * (except-
ing one premolar). If now, through some topographical change,
the whole series of Mammalia between the smooth-brained and
convolute-brained were lost to us, as by the elevation of a region,
and the absence of favorable localities or bodies of water for the
preservation of their remains, we would have to study two homol-
ogous groups, with the heterologous terms of each corresponding
with each other, as do now the genera of the Clamatores and Os-
cines of the Arcifera and Eaniformia, etc.

In the same way the characters defining Iraplacental Mam-
malia will be found transitional in some type, and this great se-
ries, homologous with the Placentals, will have to be placed in
closer connection, in its genera, with the series of the latter, with
genera of the same, perhaps, now extinct.

y. Of Mimetic Analogy,

It has been often remarked that the animals of the Equatorial
Ethiopian region were very generally of smoky and black colors.
This is remarkably the case, and the peculiarity of the genus Homo
in this respect is shared by birds, reptiles, and fishes in a consider-
able degree. This can not be traced to the effect of torrid climate,
for the same latitudes in India and the Malaysian Archipelago,
and in South America, do not produce such colors.

The similarity in color of desert types has also been remarked.
The gray sand-hue so well adapted for concealment is universal,
with few variations, in the reptiles of the Tartar and Arabian

* This I have alluded to as the non-development of the permanent series ; the
homology of the dental system of Marsupials appears, however, to be with the latter
and not with the milk series. See "Flower," "Trans. Roy. Soc," 1867. (Wortman
now denies the correctness of Flower's view, and demonstrates that the milk series
is primitive. See "Encyclopaedia of Dentistry," 1886. Ed. 1886.)

Plate ni

T. Sinclair. & Son, Phila

MIMETIC ANALjOGY.

Plate IIIc;

T. Siriclait-. & Son.Fhiia

MIMETIC ANALOGY.

PLATE III.

Fig. 1. Flaps dumerili Jan; New Gra-
nada.
Fig. 2. Elaps Icmniscatus L. ; Brazil.

Fig. 8. Flaps semipartitus D. and B ;

New Granada.
Fig. 4. Flaps psyche Daud. ; Brazil.

Fig. 5. Flaps corallinu^ Linn. ; Brazil,
Central America.

Fig. 6. Ophibohis doliatus Linn. ; South-
ern United States to Central
America.

PLATE III«.

Fig. 1. Pliocercus elapoidcs Co\)Q ', Mex-
ico.

Fig. 2. Oxyrrliopus trigeminus Tt. and
B.; Brazil.

Fig. 3. PUocercus etiryzomcs Cope ; New
Granada.

Fig. 4. Frythrolamprus cscidapil L. ;

Brazil.
Fig. 5. Cemophora cocci7ica Blum. ;

Southern United States.
Fig. 6. Frythrolamprus vcnustissimus

Neuw. ; Brazil, Ccntr'l America.

The species placed opposite to each other present similar patterns of coloration.
Figs. 3 and 4, Plate III, correspond with Fig. 3, Plate III«, and Fig. 6, Plate III,
with Figs. 5 and 6, Plate Ilia. The species inhabit the same regions, more or less
exactly, excepting the two Figs. 1. The Elapjs dumerili would have been better re-
placed by a variety of the Elaps fidvlus of Mexico, which has the red spaces black
bordered ; but a good colored plate was not accessible at the time the drawing was
made. All the figures are copied from Jan's " Iconographie Generale des Ophi-
diens " ; and the colors of such as I have not at hand for reference ( Ekqjs dumerili,
Flaps semipartitus, and Flaps psyche) are derived from the " Erpetologie Generale,"
and from Jan's "Prodrome." The species of Elaps are poisonous; the others are
harmless.

ON THE ORIGIN OF GENERA.

105

deserts, the great Sahara and the sands of Arizona and California.
There is also a tendency to produce spiny forms in such places •
witness the Stellios and Uromastix and Cerastes of the Sahara,
the Phrynosomas and horned rattlesnake of Southwestern Amer-
ica. The vegetation of every order, we are also informed, is in
these situations extremely liable to produce spines and thorns.

The serpents of the Neotropical region furnisli remarkable
illustrations of mimetic analogy. All the species of the genera
Elaps, Pliocercus, Erythrolamprus, and many of those of Oxyr-
rhopus, Ophibolus and Rhabdosoma are ornamented with black
and yellow rings on a crimson ground. The species of all these
genera are harmless, except in the case of Elaps, which is venom-
ous. We may give for this genus, as the most varied, the follow-
ing range of variation in coloration :

Pairs of black rings ;

Single black rings^far apart.

Single black rings, very close.

Oplieomorplius mimus. d
Erythrolamprus venustissi-

Elaps corrallinus. b

nigrocinctus. c
Pliocercus equalis. c

Oxyrrhopus ?
Erythrolamprus albostola-

Elaps mipartitus, d

Pliocercus euryzonus. d

Oxyrrhopus petolarius. d
Scolecophis zonatus. a

mus. a

tus. b

Ophibolus polyzonus. a
Xenodon bicinctus. b

Leptognathus anthracops. a

Single black rings loith faint
laterals.

Black rings in threes.

Sifigle black rings about
equal to intervals.

Elaps fulvius.

elegans. a

Elaps lemniscatus. b

Elaps.

Pliocercus dimidiatus. a

Pliocercus elapoides. a
Procinura semula. a

Oxyrrhopus trigeminus, b
Pliocercus elapoides var. a

Catostoma semidoliatum. a
Oxyrrhopus sebae. d
Ophibolus pyrrhomelas. h
Chionactis occipitale. h
Sonora semiannulata. h
Contia isozona. h
Chilomeniscus epliippicus. h

Species a, from Mexico and Central America. (Two species are now added, 1886.)
" b, " Brazil, Venezuela.
" c, " Central America.
" d, " western side of Andes.
" h, " Arizona and Sonora.

Many of the species in the same column are exceedingly simi-
lar, and some have little (perhaps nothing) to distinguish them but
generic characters. The most similar are almost always from the
same sub-region.* These facts are illustrated in Plates III and III a.

* Similar parallels exist between the Mexican species of Rhadinsea, Conophis,
and Erythrolamprus ( = Coniophanes). (Note, 1886.)

106 GENERAL EVOLUTION.

Similar analogies have been pointed out by Bates among the
Lepidop'tera of Brazil, and by Wallace among those of Borneo
and Celebes, etc. I call attention to these authors here without
copying them, as they will repay perusal in the originals.

A case of analogy which may belong to this class is that of the
three genera Chelys among tortoises, Pipa among frogs, and As-
predo among Siluroid fishes, species of which inhabit at the same
time the rivers of Guiana. The crania of these genera are simi-
larly excessively flattened and furnished with dermal aj^pendages,
and their eyes are very minute. The singular similarity need only
be mentioned to those familiar with these genera, to be recognized.

The bearing of the mimetic analogy, on the question of transi-
tion of types in the developmental hypothesis, is its demonstra-
tion of the independence of generic and specific characters of each
other, which may suggest the possibility of the former being
modified without affecting the latter.

These facts might have been introduced under Section II a, but
they illustrate the general laws of the present section.

IV. OF KATUKAL SELECTIO^h".

a. As affecting Class and Ordinal Characters.

The second law which may be supposed to have governed a
descent with modification, in the production of existing genera,
is the force which the environment exercises in permitting or for-
bidding the existence or persistence of new forms. The forms
which survive are supposed to have done so by virtue of their su-
perior adaptation to their environment. This is the '' natural
selection " of Darwin.

That this law is subordinate to the one first propounded must,
I think, be evident to any one who studies the assumed results of
the workings of both, as seen in the characters of genera. It is
sufficiently well known that the essential features of a majority of
genera are not adaptive in their natures, and that those of many
others are so slightly so, as to offer little ground for the supposi-
tion that this necessity has preserved them.

Both laws must be subordinate to that unknown force which
determines the direction of the great series. If a series of sup-
pressions of the nervous and circulatory systems of beings of com-
mon birth produced the "synthetic " predecessors of the classes
of Vertebrata, the direction toward which the highest advanced,

ON THE ORIGIN OF GENERA. 107

or its ultimate type, can be only ascribed as yet to the divine fiat.
So far as we can see, there is no reason or law to produce a prefer-
ence for this direction above any other direction.

If from these fixed bases descendants have attained to succes-
sive stations on the same line of progress, in subordinate features
of the nervous and circulatory systems, constituting the *^ syn-
thetic " predecessors of the orders in each class, the type finally
reached seems to rest on no other basis than the pleasure of the
Almighty.

(i. As affecting Family Characters.

If from the single species generalizing a modern order we at-
tempt to deduce synthetic predecessors of existing families, we
find some difficulty, if we attempt to see in these stages a uniform
succession of progress. A suppression of some features, and ad-
vance in others, in one and the same individual up to the period
of reproduction, would produce offspring divergent from the start,
and represent the relationship of families as we find them.

y. As affecting Generic Characters.

If the extremes of our series of genera were characterized by
structures particularly adapting them above all others to some
contemporary necessity of existence, this second law, or Darwin's,
might be regarded as primary. But the writer's experience of
comparative anatomy has led him to believe that this is not the
case, as expressed in Proposition IV, page 91.

This view had not been overlooked by Darwin, who, however,
treats of it very briefly, and appears to attach it to the theory
of adaptations, or modifications for a physiological purpose. He
says, ^^ Origin of Species," page 388 (Amer. edit., 1860) : "We
may extend this view to whole families, or even classes. The
fore-limbs, which served as legs in the parent species, may become,
by a long course of modification, adapted in one descendant to
act as hands, in another as paddles, in another as wings ; and on
the above two principles— namely, of each successive modification
supervening at a rather later age, and being inherited at a corre-
spondingly late age— the fore-limbs in the embryos of the several
descendants of the parent species will still resemble each other
closely, for they will not have been modified. But in each indi-
vidual new species the embryonic fore-limbs will differ greatly
from the fore-limbs in the mature animal ; the limbs in the latter
have undergone much modification at a rather late period of life,

108 GEi^ERAL EYOLUTION.

and having thus been converted into hands, paddles, or wings."
He then inclines to assign this change to the necessity of external
circumstance. But such modification must be the same in kind
as others, which the same hypothesis must explain, and of which
the same author remarks (page 882) : '' We can not, for instance,
suppose that in the embryos of the Vertebrata the peculiar loop-
like course of the arteries near the branchial slits are related
to similar conditions in the young mammal, which is nourished
in the womb of its mother, in the egg of the bird which
is hatched in a nest, and in the spawn of a frog under water. We
have no more reason to believe in such a relation than we have to
believe that the same bones in the hand of a man, wing of a bat,
and fin of a porpoise, are related to similar conditions of life.
'No one will suppose that the stripes on the whelp of the lion, or
the spots on the young blackbird, are of any use to these animals,
or related to the conditions to which they are exposed."

The law of natural selection, however, has no doubt been a
very important agency in the production of organic types in dif-
ferent periods of the world's history ; but the part it has played in
the determination of generic features would appear to have been
very small.

In its first effect — that of producing a structure adapted for
a particular purpose — it would seem to have acted differently to
produce the same results, and hence not to have produced any of
the more extended groups, as families, where hundreds of species
are identical in a single feature. Witness the differences in di-
verse types of the tree-frogs, each type adapting its possessor to
an aboreal life :

I. Claw-like, with globular base Hylid^.

Leptopelis.
II. Simple, obtuse-depressed at tip Ranid^. I aa and III a.

III. With a terminal transverse limb Ranid^, Hylarana et aff.

Callula.

Brachymerus.

Hi/lodes.

IV. Bifurcate Bcitrachyla.

Dendrohates.

Polypedates.

RhacopJioms.

The short foot of the Testudinid?e, where one row of pha-
langes is omitted, has been already alluded to. The gradual re-
duction of this set of bones, accompanying general modification
of form in the increased convexity of dorsal region, as Ave leave the
more aquatic and progress toward the terrestrial tortoises, would

ON THE ORIGIN OF GENERA. 109

seem to be intimately connected with difference of habit. The
increased convexity of carapace is an increased defense from fall-
ing objects — a danger to which land tortoises are far more subject
than the aquatic. Another protection, not needed by water tor-
toises so much as by terrestrial, is the faculty of closing one or
both free lobes of the plastron, as seen in the Cistudo, Sternothse-
rus, etc., or of portions of the carapace, as in Pixys, Cinixys, etc.
This might really have been produced by excessive tension on the
sternal and pelvic muscles while young, and while the sutures
were not fully interlocked. This, continued for a long time,
might have produced the result. Yet it is not easy to see what
protection the aquatic Kinosterna need in this respect, above the
Emydes of the same countries. The backs of these genera are
also as convex as are many of the terrestrial genera or Testu-
dinidse.

I can not better express my views than by quoting the follow-
ing from the pen of the late Dr. Falconer. It is extracted from
one of his essays on the Elephantidae : *

'^ Each instance, however different from another, can be shown
to be a term of some series of continued fractions. When this is
coupled with the geometrical law governing the evolution of form,
so manifest in shells of the Mollusca, it is difficult to believe that
there is not in nature a deeper-seated and innate princij^le, to the
operation of which natural selection is merely an adjunct.

** The whole range of the Mammalia, fossil and recent, can
not furnish a species which has had a wider geograjDhical distri-
bution, and at the same time passed through a longer term of
time, and through more extreme changes of climatal conditions
than the mammoth.

*'If species are so unstable and so susceptible of mutation
through such influences, why does that extinct form stand out so
signally a monument of stability ? By his admirable researches
and earnest writings, Darwin has, beyond all his contemporaries,
given an impulse to the philosophical investigation of the most
backward and obscure branch of the biological sciences of the
day ; he has laid the foundation of a great edifice ; but he need
not be surprised if, in the progress of erection, the superstructure
is altered by his successors, like the Duomo of Milan, from the
Roman to a different style of architecture.

* See writings of Hugh Falconer, vol. ii (ed. by Murchison).

110 GENERAL EVOLUTION.

'' The inferences which I draw from these facts are not op-
posed to one of the leading propositions of Darwin's theory.

*^ With him I have no faith in the opinion that the mammoth
and other extinct elephants made their appearance suddenly, after
the type in which their fossil remains are pre:ented to us. The
most rational view seems to be, that they are in some shape
the modified descendants of earlier progenitors. Eut if the as-
serted facts be correct, they seem clearly to indicate that the older
elephants of Europe, such as U. meridionalis and E. antiqmis,
were not the stocks from which the later species, E. primigenius
and E. africanus sprung, and that we must look elsewhere for
their origin. The nearest affinity, and that a very close one, of
the European E. mericlio7ialis, is with the Miocene E. (Loxod.)
planifrons of India, and of E. primige?iius with the existing In-
dian species.

*^ Another reflection is equally strong in my mind, that the
[theories of the origin of] species by ^ natural selection,' or a pro-
cess of variation from external influences, are inadequate to ac-
count for the phenomena. The law of Phyllotaxis, which gov-
erns the evolution of leaves around the axis of a plant, is nearly
as constant in its manifestation as any of the physical laws con-
nected with the material world."

6. Js affectiiig Specific Characters.

As I have hitherto attempted to prove that the higher grade
of groups, or, in other words, the higher grade of characters,
could not have had their origin through natural selection alone,
though admitting it as a conserving or restricting principle, I
now come to ground where natural selection must be allowed full
sway. The " origin of species " is not the object of this essay, as
a greater has gone before me, and has done a great deal toward
showing that a selective power, deiDcndent on adaptation and tele-
ological relation, has favored or repressed, or even called into ex-
istence, the varied peculiarities that characterize species and races.
I will therefore only refer to his well-known works on the ^^ Origin
of Species " and the ^' Modifications of Animals under Domestica-
tion."

I may add that it is within the range of possibility that that
grade or kind of characters found to define i\iQ family group may
be more or less the result of natural selection.

Acceleration and retardation are also far from excluded from

ON THE ORIGIN OF GENERA. m

the probable causes of specific characters. The species of many
genera do exhibit a proportion of characters which are the succes-
sive stages of that one which progresses farthest, as the species of
Amblystoma in the position of their teeth, nostrils, form of tail,
and coloration ; of Hyla in form of vomerine teeth, etc. But the
majority of specific characters are of divergent origin — are 'Amor-
phic " as distinguished from developmental.

e. On Metaphysical Species.

One of the arguments employed against the developmental
hypothesis, in any form, is that that inherent "potentiality,"
which causes that like shall always produce like, is a metaphysi-
cal being, which can not be transformed, and which holds the
structure which it vivifies as a material expression or stamp of it-
self, and which therefore can not be changed.

One expression of this inherent metaj^hysical specific individu-
ality, if the term may be allowed, has been said to be the peculiar
traits of the intelligence of species, their motions, voices, and in-
stincts. But intelligence of all animals is susceptible of impres-
sions, the lower the intelligence the less susceptible, and the more
automatic. But, as we rise in the scale of animal being, this im-
pressibility and capacity for education is undeniably exhibited by
the dog, horse, and all the well-known domesticated companions
of man. There can, in view of the capacities of Aves and Mam-
malia in these respects, be little doubt that all animals are edu-
cated by the *' logic of events," that their intelligence, impressed
by changed circumstances, can accommodate itself more or less to
them, and that there is nothing in this part of their being opposed
to the principle of "descent with modification."

There is another difficulty in the way of accepting metaphys-
ical peculiarity or progenitiveness as isolating species. It is
marked often strongly in races or varieties, which no one pre-
tends to have had distinct origin. Here like produces like con-
tinually, though not persistently, but sufficiently to show that it
resides in varieties of common origin. The isolation of allied
species in fact depends, I believe, solely on the supremacy of the
automatic over the intelligent spirit. When the intelligent rises
above the bounds of nature, or the automatic, the mixture or
separation of allied species depends merely on circumstances of
necessity, determined by that intelligence.

But the metaphysical '' potentiality " loses all basis, if the law

112 GENERAL EVOLUTION.

of acceleration and retardation be true, for in accordance with it,
at certain times, like does not produce like,

V. OF EPOCHAL EELATIOI^S, OR THOSE MEASURI2^G GEOLOGIC

TIME.

If it can be shown that groups haying the develo2)mental rela-
tion above insisted on are contemporaries, and if it can be shown
that this relation is identical in kind with that which we regard
as measuring the successions of geologic time, we will be led to
doubt the existence of any very great interruptions in the course
of this succession throughout geologic time. And if we can show
that faunae so related are more or less characteristic of distinct por-
tions of the earth's surface, at the present time, we will be led to
antici23ate that contemporaneous faunge in different regions, during
geologic periods also, bore such a relation. If this proposition be
true, we are led to the further conclusion, which is at variance
with received canons, that identity of faunae proves successional
relation in time, instead of synchronism.* That this will ulti-
mately be demonstrated appears highly probable to the writer,
though, as yet, the evidence is but fragmentary.

If the relations expressed under the terms homology and het-
erology, taken together with the observations on metamorphosis,
render it j^robable that a number of genera have reached their ex-
pression-points, or periods of metamorphosis, at near the same
time in geologic history, an important point has been gained.
If we can render it probable that a change in any organic charac-
ter has been nearly simultaneous throughout a large extent of
specific forms, the change becomes, on the latter account alone,
of higher than generic value, but characteristic of such groups as
Marsupialia, Clamatores, Acrodonta, Arcifera, Heterocerca, and
the like.

We have here, also, an important element in the estimation of
the value of apj^arent interruptions in the geological history of
the life of the globe. These interruptions, it is true, are greater
than any such theory as the present can bridge over ; yet such a
theory, if true, lessens their importance. They are in any case
well accounted for on the theory of the existence of periods of
elevation, during which the life of a given region is necessarily
almost entirely lost to us, through lack of means of preservation
of their remains.

* This, view has been insisted on by Huxley.

ON" THE ORIGIN OF GENERA. 113

We may also compare such extended metamorphoses with
those of cosmical matter, such as when, in the course of ages, a
primeval vapor has in a short time collapsed to the liquid form, or
as when the vast of liquid in turn has shrunk to its solid con-
dition ; both alike for ages approaching their change, yet sta-
tionary in external relations till the moment of transition has
arrived.

The following are the zoological relations of the groups al-
ready referred to :

The most generalized group of fishes of the Regio Neotropica
is that of Characins. Its type, in respect to fin-structure, which
is common to all the Malacopterygians, is that of an undeveloped
stage of the Acanthopterygians, the adipose fin being an undevel-
oped cartilaginous fin, and the cartilaginous fin an undeveloped
spinous fin.* It may be said to be the highest among Malacop-
terygians, if we look to the conq^lete oviducts, opercula, jaws, etc.,t
but it is the lowest as removed farthest from the extreme of
Malacopterygian peculiarities, as being most generalized or em-
bracing representatives of all the rest, and approaching nearest
the types of the past — the Ganoids. Tor example, Butyrinus and
Vastres may be compared with Amia. The family is distributed
chiefly in the Southern Hemisphere.

The genus Orestias, which Agassiz says is characterized by a
feature which exists in the immature state of all other Oyprino-
donts — the absence of ventral fins — is only found in the Neotrop-
ical region.

Of the yenomous serpents, the inferior group, the Proterogly-
pha, belong to the Southern Hemisphere, and the Australian and
Neotropical regions almost exclusively embrace by far the greater
proportion. Australia contains none other.

The Iguanian lizards are lower than the Acrodont, exhibiting
a larval type of detention, and one characteristic of all lower Sau-
ria and Batrachia. The only acrodont type of Ophiosaura (Trog-
onophis) is Old World.

The New World Teidas have not the extent of ossified tem-
poral roof that their representatives, the Old World Lacertidae,
have. So the chiefly Neotropical Anguidae haye the tongue part-

* Kner, " Ueber den Bau der Flosscn."

\ This is the correct view, for this family and the Siluroids are the most special-
ized of the Malacopterygian fishes. (1886.)
8

114 GENERxiL EVOLUTIOK

ly of papillose type of tlieir Old World representatives, the Zonu-
ridae, and partly the smooth or scaly type of the cosmopolite Scin-
cidse, which are inferior to them.

The snake-like forms of the families of the Lacertilia Lepto-
glossa greatly predominate in the Southern Hemisphere ; also
those with undeveloped palj^ebrae.

The Neotropical type of Testudinata is quite coincident with
the family Characinidae in relations. It is, like it, largely dis-
tributed over the Southern Hemisphere, and like it may be re-
garded, in respect to its pelvic peculiarities, as higher than the
remaining types, but in its generalized character and relationship
to the past periods may be called lower.

The Neotropical type of Batrachia anura, that is, the Arcifera,
is lower in developmental characters than the opposed series, the
Eaniformia ; such of the latter as are found in its limits partake
in some way of larval incomjileteness. The Arcifera are chiefly
distributed elsewhere in Australia, where no Eaniformia exist.*
Those genera of Old World Eaniformia of the lowest or toothless
group, which display the least development of the cranial bones,
as Brachymerus and Breviceps, are of the Southern Hemisphere —
South African.

The Pullastrine birds are a generalized group, inferior to the
group opposed to them — the Gallinae. Their typical forms, like
the last, are distributed to the Neotropical and Australian regions :
the outliers (pigeons) are not so numerously distributed in the
other regions.

The Struthious birds, the most synthetic of the class, belong
exclusively to the Southern Hemisphere ; as is well known, they
chiefly abound in Australia and its adjacent islands, with an abun-
dant outlying type — the Tinamus — in South America.

The penguins, which only of all birds display the metatarsus
nearly divided, inhabit the Antarctic regions and Cape Horn.

* The Eucnemis bicolor, Gray, would appear to be an exception, were its generic
and subordinate affinities truly represented by its name. I have examined the type
specimen through the kindness of Dr. Giinther, and can state that it is not an Ixa-
lus {= Eucnemis), and does not even belong to the Eaniformia, but is an Arcifer of
the family HyUdae. If it be not a young Calamita or Hyla, it will be a Hylella near
the K carnea type. (Boulenger, in 1882, determined it to be a Hylella. Ed.
1886.)

Giinther states that Hylorana erpthraea has been found at the extreme northern
point — Cape York — of Australia. If so, the case is parallel to the occurrences of
the Raniform Ranula in northern South America.

ON THE ORIGIN OF GENERA. II5

The Clamatorial type of the Passeres exhibit larval characters
in the non-development of the singing apparatus, and the scaled
or nearly naked tarso-metatarsus. These are chiefly South Amer-
ican.

Of Mammalia, the placentals without enamel on their teeth,
which, in this respect, never reach the full development of the
class, whose dentition is also monophyodont, i. e., the Edentata,
inhabit only the Southern Hemisphere, and almost altogether the
Neotropical region. The implacental Mammalia, also (except in
one tooth) monophyodont, which approach birds and reptiles in
so many respects, are confined to the Southern Hemisphere, and
chiefly, as all know, to Australia.

Of the Quadrumana, the Platyrrhine group is known to be in-
ferior to the Catarrhines : the former presents an entirely embry-
onic condition of the os tympa7iicum, which is passed by the latter
in early age ; * it contains also the only clawed genus of the true
monkeys. It is confined to the Neotropical realm. To Madagascar,
also of the Southern Hemisphere, and nearest in many ways to
the Neotropical, pertain the lowest families of the Quadrumana,
the Lemuridae and Chiromyidas ; the former presenting brains
without convolutions, and approaching in many ways the Insec-
tivora ; the last imitating, at least, a Eodent.

There are also other reasons for the inferiority of South Amer-
ica. Its deer, which are few, include those which never produce
more than the ^^dague," or the first horn of the northern Cervus,
and also those which never get beyond the fourth step in the de-
velopment of the lower group of R. Nearctica.

The Loricariidae, of South America, I am informed by Prof.
Agassiz, possess the foetal pupil of the vertebrate type.

If we glance at Coleoptera we find the great predominance of
the groups with undeveloped tarsus, the three- and four-jointed
Trimera and Tetramera, and of the lower group with undeveloped
sternum, f the Rynchophora, in the Neotropical region.

Among Lepidoptera it is known that the most gigantic of the
species of the Neotropical region are Noctuidae (Erebus, etc. ), and
that in that region this low type of the order reaches its greatest
development. The largest forms of the Regio Nearctica, as well
as Pal^arctica, are representatives of the higher type of the Satur-

* See Dr. H. Allen, "Proceed. A. N. S.," Phila., 186Y.
\ Leconte, American Association, 1867.

116 GENERAL EVOLUTION.

niidse (Atticus, Telea, etc.), while the largest and most powerful
of this order in the Palaeo tropical (Indian) region are the Papilio-
nid forms of Ornithoptera, etc., the generally admitted crown and
head of all. Of course other types, both higher and lower, are
largely developed in each and all of these regions, and the signifi-
cance of the aboye facts is perhaps only to be seen when taken in
connection with a large number of others pointing in the same
direction.

Two or three comparisons of different faunae may be brought
forward finally. First, returning to the birds, a survey of some
of the differences between the birds of Panama, Pennsylvania, and
Palestine may be made.*

Tristram noticed three hundred and twenty-two species of
birds within the range of the ancient territory of Palestine. Of
these two hundred and thirty were land and ninety-two water
birds, i. e., Natatores and the wading Cursores. Of the two hun-
dred and thirty, seventy-nine are common to the British Islands,
and thirty-six of them are found in China, but a small j^roportion
extending their range to both these extremes. Of the water birds,
which are always more widely distributed, fifty-five of the ninety-
two are British and fifty-seven Chinese. Twenty-seven appear to
be confined to Palestine, and to the immediately adjacent country ;
the largest of these is a crow.

Taking the two hundred and thirty land birds at a glance,
we find the utter absence of so many of the well-known forms
that enliven our grounds and forests. The absence of Tanagridse
(including Sylvicolidae) and Icteridse, changes the aspect of the
bird-fauna at once. What have we here, then, of nine-quilled
Oscines to enliven the meadows like our swarms of blackbirds, or
fill the tree-tops and thickets with flutter like our wood-warblers ?
Nothing ; for the twenty-four species of finches, Fringillidae, will
but balance our own, though the genera are all different but four,
and they the most weakly represented by species. We must look
to the higher series, the ten- quilled song-birds, for the missing
rank and file. While a much larger extent of the Eastern United
States possesses fifty species of these types, the little Palestine has
already furnished a list of one hundred and twenty-eight.

First, of the crows, which verge nearest Icteridae hj the star-
lings, we have thirteen species against five in our district of the

* From the "American Naturalist," 1868, by the author.

ON" THE ORIGIN OF GENERA. ^^^

United States, and not less than seven of the typo genus Corvus
to our one common and two rare. Of these two are of the laro-er
species, the ravens. If we turn to the cheerful larks, we find the
proportion again the same ; fifteen species for Palestine and one
for the whole United States. One congener of our species occurs
there ; the other genera call to mind the African deserts and Rus-
sian steppes. Motacillidse, again, ten to one against our fauna. We
have two Tanagridae to imitate them, besides the one true relative.
In swallows we are about equal, and in the forest-haunting Parid^
— titmice and wrens — we exceed a little ; but the comparison of
Sylviidse and Turdidas is most striking. These highest of the bird
series, especially made to gladden man's haunts with song, exceed
in number all the other ten-quilled Oscines together inhabiting
Palestine, amounting to seventy-five species. In our correspond-
ing region of the United States nineteen species is the quantum.
It is true no mocking-bird or wood-robin is known away from our
shores, but Palestine has the nightingale, the black-cap, and the
true warblers or sylvias, which, while they glean from shrub and
tree their smallest insect enemies, as do our equally numerous
small Tanagridse, have much louder and sweeter voices.

Our solitary bluebird represents the long-winged Turdidae ; in
the Holy Land there are twenty species corresponding, though
none are of our genus. There are, indeed, but three genera of
these two families common to both countries. One of these, La-
nius, the butcher-bird, occurs here in one species, in Palestine
in six.

Turning now to a lower series, we look in vain for Clamatorial
perchers ; that series which gives us the fierce king-bird and queru-
lous pewee, and which peoples South America with thrush and
warbler, and shrike and tree-creeper.

In taking a hasty glance over the lower groups, where the carot-
id arteries begin to be double, as the Syndactyli, we find Palestine
too far from the tropics to present us with much array ; but in
the related zygodactyles our forest-crowned continent must claim
great pre-eminence. It has but a solitary Picus, while we have
eight in the immediate neighborhood of lat. 40°, in our Eastern
States.

I will close with the birds of prey. Four swamp-hawks, eleven
species of falcons, four kites, and eight native eagles, form a list
unequaled in the annals of nobility by any land. There are to-
gether thirty-one species of Falconidae, and of Vultures four. The

118 GENEKAL EVOLUTION.

eagles appear to be all common, among them the most magnificent
birds of prey, the imperial and golden species of these creatures.

To the ornithologist, acquainted with the fauna of North
America, it will thus be readily perceived that, in comparison, the
ornis just examined, possesses more numerous representatives of
the higher groups of the birds, and among lower groups possesses
chiefly those of superior grade, or lacks them altogether. Let us,
however, compare it with that of Central America, where varied
surface and temperature offer even greater opportunity for variety,
within quite as restricted an area.

The bird fauna has been found by Messrs. Sclater and Salvia
to embrace about three hundred and eighty-five species, which is
sixty-three more than were mentioned to occur in Palestine, which
is open on three sides to the great continent. Eighty of three
hundred and forty-eight land birds are characteristic of Central
America ; and those which find their kin limited to the Isthmus
and adjoining regions of New Grenada and Equador amount to
about seventy-five more. Twenty-seven is the number not known
to extend beyond the boundaries of Palestine ; as to the Middle
States of our Union, not one species has been shown to be restricted
within such narrow limits.

A single species occurs in Europe ; this is the fish-hawk, an
animal which combines the cosmopolite habit of the sea-bird with
the powerful flight of the bird of prey. This is also the only sj^e-
cies common to the Panama and Palestine catalogues.

The birds of prey are numerous — twenty-nine species. Among
these there is no true eagle or falcon, and of the nineteen genera
but four belong to the fauna of the Holy Land. There is but one
species to represent the great grouse family, but, instead, three
families of their South American imitators, the Pullastrse, instead
of the one — that of the Pigeons — slimly represented in Palestine,
and in North America as well.

Coming to the closer test of superiority, the Passeres — those
delicate creatures, apparently so dependent on those laws which
govern increase and provision, and so affected by the changes that
man works in the face of Nature — what do we find ? We count
one hundred and six distinct species. There are none in Pales-
tine. Of songsters, the Oscines, ninety-six species, await man's
conquest of the wilderness, to increase in numbers and to display
their gifts, while Palestine rejoices in a whole army of them. But
the contrast is more remarkable if we analyze these forms. Of the

ON THE GRIGIN OF GENERA. 119

Isthmian Oscines, seventeen only hold the first rank, by virtue of
their additional, the tenth primary quill, while this feature marks
one hundred and twenty-eight species of Palestine. As we rapidly
follow the line to the point where its extreme is manifested, in the
family of the Thrushes or Turdidae, Panama is left but two soli-
tary pioneers of these songsters of the North, while seventy-five
species represent the family in Palestine.

The comparison between different faunae exhibits an apparent
gradation in some other groups equally curious. Thus, the true
Cyprinidae in the Palaearctic region reach a great development,
and produce the highest number of teeth on their pharyngeal jaws
known, as well as attains the greatest bulk and importance. The
number of these teeth is usually seven to five in the inner row ;
only two or three genera exhibit only four on both. In the Ne-
arctic region the number of teeth is almost always 4 — 4, more
rarely 4 — 5, and very seldom as high as 5 — 5. The species of the
family are excessively numerous, but are, with scarcely any excep-
tion, of small size and weak organism. These statements apply to
those of the eastern district of the region between the Rocky
Mountains and the Atlantic. Similar types occur in the northern
region of the Neotropical — Mexico, but in no great numbers.
Farther south the family disappears, its place being sujoplied by
the generalized family of Characinidae.

I have already alluded to the great variety of the highest or
pentamerous carnivorous beetles in the Palaearctic region. They
are extremely abundant in the Nearctic, while the intermediate
territory, the Sonoran and Mexican sub-districts, are the head-
quarters of the next lower form, the Tenebrionidae, which have
the tarsal joints 4 — 5. These give place in the Neotropical to the
multitudes of the still lower series — those with the joints 4 — 4 and
3 — 3 — Tetramera and Trimera.

The preceding comparisons indicate that an inherent difference
between the types of a continent exists at the present time, tliough
the difference is subordinated to a universal distribution of the
higher groups throughout the earth. Has this state of things ex-
isted for any long period, or is it a result of different progress in
the same group since the human period ? This brings us neces-
sarily to a consideration of the truths of paleontology, especially
of the last periods, which have been already urged by Darwin.
Thus the present fauna of Australia was preceded in the Post-Pli-
ocene and Pliocene by forms possessing similar peculiarities, and

120 GENERAL EVOLUTION.

belonging to the same classes. That is by herbivorous and car-
nivorous marsupials and monotremes, and by Varanid Sauria, all
of greater size than their predecessors.

The same fact is well known of the Neotropical region, its
present peculiar Edentata having been preceded by giants of the
same type in the Post- Pliocene and Pliocene.

In the Nearctic region peculiar existing genera, as Procyon,
Alces, Castor, Bos, Sciurus, Arctomys, Lepus, Ovibos, Sorex, Me-
phitis, Felis, Ursus, Menopoma, Aspidonectes, Orotalus, are rep-
resented by Post-Pliocene fossils.

The same occurs in the later Palsearctic formations, where Cer-
vus. Bos, Canis, Mustelidse, Insectivora, Vipera, Alytes, Triton,
etc., are allied predecessors of existing types. In the Palseotrop-
ical area a wonderful development of Elephas and Gavialis preceded
the same types of the present.

Prior to these faunas another state of things has, however, ex-
isted. North America has witnessed a withdrawal of a Neotrop-
ical fauna, and the Palaearctic the retreat of an Ethiopian type.
During the Post-Pliocene in North America, Neotropical genera
were to Nearctic as 12 to 29, as the record now stands. In the
Pliocene beds of Pikermi (Greece) antelopes, giraffes, rhinoceros,
hippopotamus, huge manis,* monkeys, monitors, and other genera
and species of African relationship are the prevailing forms.

Still earlier, a strong mingling of Nearctic, and more of Neo-
tropical types, abounded in the Palaearctic. The genera Chelydra,
Andrias, Podocnemis,t Platemys, Caviiform, Psammoryctid and
Hesperomys-like Eodentia, Opossums, and Raccoon-like Carnivora.

We have, then, three important terms from which to derive a
theory of the creation : 1, the existing six faunae bear in many of
their parts developmental relations to one another ; 2, they were
preceded immediately by faunae similar to them in each case, but
more remotely by faunae like that now next lower.

On the whole, there can be no doubt of the truth of the gen-
eralization : That the Southern Hemisphere is a geologic stage
hehind the Northern Hemisphere in progress, on account (1) of
its perfection in types extinct in the Northern, and (2) inferiority
in modern types prevalent in the Northern.

In order, however, to demonstrate this jDoint more fully, let us

* Ancylotherium, Macrotherium.

f P. howcrbanJcii {Platemys^ Owen). P. Icevis {JEinys, Owen).

ON THE ORIGIN OF GENERA. ;121

examine to what extent the higher types exist in the Southern
and lower or ancient in the Northern.

The Percoid fishes and their allies have Australian and South
American representatives in their fresh waters, but they are as
mere outliers of the great mass in the Northern Hemisphere. The
higher type of venomous serpents (Solenoglypha) occur in both
the Ethiopian and Neotropical regions, but they j^reponderate in
the Northern Hemisphere. The higher group of the Saurians
(the Acrodonta) abounds in the Ethiopian and Australian regions ;
they are as abundant in the Indian and Palaearctic regions of the
Northern Hemisphere. In the Southern, also, by Uromastix and
the Rynchocephalia, they approach nearest the ancient types of the
Dicynodontia and the Crocodilia. Lacertidae, and not Teidse,
occur in the Ethiopian ; but they are but a proportion of the
whole, which chiefly exists in the Nearctic.

Eaniform, and not Arciferous Anura, populate South Africa ;
they, however, form but a small proportion compared with the
great series of the Nearctic, Palaearctic, and Palseotropical regions.
It is, however, superior in Anura to the Nearctic, taken by itself.

Rasorial birds, and not Pallastrae, are the food species of South
Africa ; but they do not compare in abundance or size with those
of the three regions just mentioned.

Moreover, but few Clamatores exist in either Australia or
Ethiopia. The Oscine types are abundant ; nevertheless, they can
not be compared in relative abundance with those of the northern
regions. It must also be remembered that the migratory capa-
bilities of birds render them less expressive of the true nature of
any fauna.

The higher family of the Quadrumana, the Simiidae, replaces
in Africa the Cebidae of the Neotropical ; they are, however, most
abundant in the Palaeotropical region, in the other hemisphere.

There are two ancient or inferior types of the Northern Hemi-
sphere : First, its fishes, the Sturgeons of the Nearctic and Palse-
arctic, and the Gars of the Nearctic* The latter only have rep-
resentatives in the Southern Hemisphere, Polypterus and Cala-
moichthys in Africa, and so may be said to be equally distributed ;
but the former are confined to the north. We do not know, how-
ever, whether they are of a modern or an ancient type, nor do we

* Subsequent investigations have proved that Polypterus and Calamoichthys are
of much more ancient type than gars and sturgeons. (Ed. 1886.)

122 GENERAL EVOLUTION.

know of extinct sturgeons in the Southern Hemisphere. Indeed,
the Ganoid series is not well defined or known as yet. If, as
Agassiz states, the Siluroids pertain to it, it is cosmopolitan,
though least represented in the Palasarctic.

Second, the Tailed or Urodele Batrachia. This order, entirely
characteristic of the Northern Hemisphere, is a group which com-
bines characters of Anura with those of the ancient forms, and
possesses in its Nearctic types many of low development. The
Gymnophidia of the Southern HemisjDhere can not be considered
inferior to them. In the possession of this group the Northern
Hemisphere presents its first element of inferiority.

The preceding comparisons indicate also the relations of the
regions proper to each other. It is obvious enough that the Ethi-
opian is much superior to the two others of the Southern Hemi-
sphere. As to the Australian and Neotropical, the former must
still be regarded as probably the most ancient, though possessing
at the same time a much stronger admixture of northern forms.
I liave already presented the relations, with the inferior forms of
each, thus : *

R. Australis. — Inferior in possessing Monotrematous and Marsu-
pial Mammalia, Pullastriform and Struthious Birds, Serpent-
iform Pleurodont Lacertilia, Arciferous Batrachia, Pleuro-
dire Tortoises, its Elapid venomous snakes, and the whole
Flora, according to linger.

B, Neotropica. — Marsupial and Edentate Mammalia, Inferior
Rodentia and Quadrumana, Pleurodire Tortoises, Pleurodont
Lacertilia, Arciferous Batrachia, Clamatorial and Pullas-
triform Birds, Characin and Erythrinid Malacopterigii.

Conclusions,

The following may be looked upon as conclusions which have
been indicated in the preceding pages :

I. Species have developed from pre-existent species by an in-
herent tendency to variation, and have been preserved in given
directions and repressed in others by the operation of the law of
natural selection (Darwin).

II. Genera have been produced by a system of retardation or
acceleration in the development of individuals ; the former on
pre-established, the latter on preconceived lines of direction. Or,

«■ "

Jour. Acad. Nat. Sci.," Philada., 1866, p. 109.

ON THE ORIGIN OF GENERA. 123

in other words, that while nature's series have been projected in
accordance with the hiw of acceleration and retardation, they have
been limited, modified, and terminated by the law of natural se-
lection, which may itself have operated in part by the same law.

III. The processes of development of specific and generic, char-
acters have not proceeded pari passu, transitions of the one kind
not being synchronous with transitions of the other ; and that,
therefore, species may be transferred from one genus to another
without losing their specific characters, and genera from order to
order without losing their generic characters.

IV. And as the heterologous terms of the peculiar homologous
groups present an ^^ inexact parallelism" with each other; and
as types related by inexact parallelism are each among themselves
exact parallels in separate series, whose earliest members present
*^ exact parallelisms " with each other, it follows —

Y. That the heterologous terms or genera in the later series
are modified descendants of those of the earlier series ; in other
words, that certain groups higher than genera are produced from
others of similar high value by "descent with modification."

YI. That the result of such successional metamorphoses will
be expressed in geologic history by more or less abrupt transitions
or expression-points, rather than by uniformly gradual succes-
sions.

Of course, under the conclusion stated in Proposition II, the
genus Homo has been developed by the modification of some pre-
existent genus. All his traits which are merely functional have,
as a consequence, been produced during the process. Those traits
which are not functional, but spiritual, are of course amenable to
a different class of laws, which belong to the province of religion.

III.

ON THE THEOEY OF EVOLUTION".

At a meeting of the Philadelphia Academy of Natural Sci-
ences, held February 22, 1876, Prof. Cope gave a history of the
progress of the doctrine of evolution of animal and vegetable
types. While Darwin has been its prominent advocate within
the last few years, it was first presented to the scientific world, in
a rational form, by Lamarck, of Paris, at the commencement of
the present century. Owing to the adverse influence of Cuvier,
the doctrine remained dormant for half a century, and Darwin
resuscitated it, making important additions at the same time.
Thus Lamarck found the variations of species to be the primary
evidence of evolution by descent. Darwin enunciated the law of
*^ natural selection" as a result of the struggle for existence, in
■accordance with which "the fittest" only survive. This law,
now generally accepted, is Darwin's principal contribution to the
doctrine. It, however, has a secondary position in relation to
the origin of variation, which Lamarck saw, but did not account
for, and which Darwin has to assume in order to have materials
from which a " natural selection " can be made.

The relations exhibited by fully grown animals and plants
with transitional or embryonic stages of other animals and plants,
had attracted the attention of anatomists at the time of Lamarck.
Some naturalists deduced from this now universally observed
phenomenon that the lower types of animals were merely re-
pressed conditions of the higher, or, in other words, were embry-
onic stages become permanent. But the resemblances do not
usually extend to the entire organism, and- the parallels are so
incomplete that this view of the matter was clearly defective,
and did not constitute an explanation. Some embryologists, as
Lereboullet and Agassiz, asserted that no argument for a doctrine
of descent could be drawn from such facts.

The speaker, not adopting either view, made a full investiga-

ON THE THEORY OF EVOLUTION. 125

tion into the later embryonic stages, chiefly of the skeleton of the
Batrachia, in 1865, and Prof. Hyatt, of Salem, Mass., at the
same time made similar studies in the development of the Ammo-
nites and Nautili. The results as bearing on the doctrine of evo-
lution were published in 1869 (in ^^The Origin of Genera"). It
was there pointed out that the most nearly related forms of ani-
mals do present a relation of repression and advance, or of perma-
nent embryonic and adult type, leaving no doubt that the one is
descended from the other. This relation was termed exact paral-
lelism. It was also shown that, if the embryonic form were the
parent, the advanced descendant was produced by an increased
rate of growth, which phenomenon was called acceleration ; but
that if the embryonic type were the offspring, then its failure to
attain to the condition of the parent is due to the supervention of
a slower rate of growth ; to this phenomenon the term retarda-
tion was applied. It was then shown that the inexact parallelism
was the result of U7iequal acceleration or retardation ; that is, ac-
celeration affecting one organ or part more than another, thus
disturbing the combination of characters which is necessary for
the state of exact parallelism between the perfect stage of one
animal and the transitional state of another. Moreover, accelera-
tion implies constant addition to the parts of an animal, while re-
tardation implies continual subtraction from its characters, or
atrophy. He had also shown (''Method of Creation," 1871) that
the additions either appeared as exact repetitions of pre-existent
parts, or as modified repetitions, the former resulting in simple,
the latter in more complex organisms.

Prof. Haeckel, of Jena, has added the keystone to the doc-
trine of evolution in his gastrsea theory. Prior to this generaliza-
tion it had been impossible to determine the true relation existing
between the four types of embryonic growth, or, to speak other-
wise, than that they are inherently distinct from each other.
But Haeckel has happily determined the existence of identical
stages of growth in all of the types of eggs, the last of which is
the gastrula ; and beyond which the identity ceases. Not that
the four types of gastrula are without difference, but this differ-
ence maybe accounted for, on plain principles. In 1874, Haeckel,
in his "Anthropogenic," recognizes the importance of the irregu-
larity of time of appearance of the different characters of animals,
during the period of growth, as affecting their permanent struct-
ure. While maintaining the view that the low forms represent

126 GENERAL EVOLUTION.

the transitionaL stages of the higher, he proceeds to account for
the want of exact correspondence exhibited by them at the present
time, by reference to this principle. He believes that the rela-
tion of parent and descendant has been concealed and changed
by subsequent modifications of the order of appearance of charac-
ters in growth. To the original, simple descent he applies the
term palingenesis ; to the modified and later growth, coenogenesis.
The causes of the change from palingenesis to coenogenesis he re-
gards as three, viz., acceleration, retardation, and heterotopy.

It is clear that the two types of growth distinguished by Prof.
Haeckel are those which had been pointed out by Prof. Cope in
"The Origin of Genera," as producing the relations of "exact"
and "inexact parallelism"; and that his explanation of the
origin of the latter relation by acceleration or retardation is the
same as that of the latter essay. The importance which he at-
taches to the subject was a source of gratification to the speaker,
as it was a similar impression that led to the publication of " The
Origin of Genera " in 1869.

It remains to observe that the phenomena of exact parallelism
or palingenesis are quite as necessarily accounted for on the prin-
ciple of acceleration or retardation as are those of inexact paral-
lelism or coenogenesis. Were all parts of the organism acceler-
ated or retarded at a like rate, the relation of exact parallelism
would never be disturbed ; while the inexactitude of the parallel-
ism will depend on the number of variations in the rate of growth
of different organs of the individual, with additions introduced
from time to time. Hence it may be laid down that synchronous
acceleration or retardation produces exact parallelism, and lietero-
chronous acceleration or retardation produces inexact parallel-
ism.

In conclusion, it may be added that acceleration of the seg-
mentation of the protoplasma or animal portion of the primordial
Qgg, or retardation of segmentation of the deutoplasma or vegeta-
tive half of the Qgg, or both, or the same relation between the
growth of the circumference and center of the egg, has given rise
to the four types which the segmentation now presents.

An analysis of the laws of evolution may be tabulated as fol-
lows :

ON THE THEORY OF EVOLUTION.

127

-I:?

1 ^. ( Exact repetition .^

acceUrahon, \ Modified repetition I

which proceeds by ] g^^^^^^^pyj -

retardation^ j Exact atrophy ^

Avhich proceeds by ( Inexact atrophy (or senility r-' ^j.

o Si:

O Co

s 2.

Co i_l

*
*

a, a
O £1

t-b 05

* So called by Prof. Hyatt.

IV.
ON THE HYPOTHESIS OF EVOLUTION:

PHYSICAL AND METAPHYSICAL.

" Man shall not live by bread alone, but by every word that proceedeth out of the

mouth of God shall man live."

There is apparently considerable repugnance in the minds of
many excellent people to the acceptance, or eyen consideration, of
the hypothesis of development, or that of the gradual creation by
descent, with modifications from the simplest beginnings, of the
different forms of the organic world. This objection probably
results from two considerations : first, that the human sj^ecies is
certainly involved, and man's descent from an ape asserted ; and,
secondly, that the scheme in general seems to conflict with that
presented by the Mosaic account of the Creation, which is regarded
as communicated to its author by an infallible inspiration.

As the truth of the hypothesis is held to be infinitely probable
by a majority of the exponents of the natural sciences at the pres-
ent day, and is held as absolutely demonstrated by another por-
tion, it behooves those interested to restrain their condemnation,
and on the other hand to examine its evidences, and look any con-
sequent necessary modification of our metaphysical or theological
views squarely in the face.

The following pages state a few of the former ; if they suggest
some of the latter, it is hoped that they may be such as any logical
mind would deduce from the premises. That they will coincide
with the spirit of the most advanced Christianity, I have no
doubt ; and that they will add an appeal through the reason to
that direct influence of the Divine Spirit which should control the
motives of human action, seems an unavoidable conclusion.

I. PHYSICAL EVOLUTIOK.

It is well known that a species is usually represented by a great
number of individuals, distinguished from all other similar associ-

ON THE HYPOTHESIS OF EVOLUTION. 129

ations by more or less numerous points of structure, color, size,
etc., and by habits and instincts also, to a certain extent; that
the individuals of such associations reproduce their like, and can
not be produced by individuals of associations or species v^^hich
present differences of structure, color, etc., as defined by natural-
ists ; that the individuals of any such series or species are incapa-
ble of reproducing with those of any other species, with some
exceptions ; and that in the latter cases the offspring are usually
entirely infertile.

The hypothesis of Cuvier assumes that each species was created
by divine power as we now find it at some definite point of geo-
logic time. The paleontologist holding this view sees, in accord-
ance therewith, a succession of creations and destructions marking
the history of life on our planet from its commencement.

The development hypothesis states that all existing species
have been derived from species of pre-existent geological periods,
as offspring or by direct descent ; that there have been no total
destructions of life in past time, but only a transfer of it from
place to place, owing to changes of circumstance ; that the types
of structure become simpler and more similar to each other as we
trace them from later to earlier periods ; and that finally we reach
the simplest forms consistent with one or several original parent
types of the great divisions into which living beings naturally fall.

It is evident, therefore, that the hypothesis does not include
change of species by hybridization, nor allow the descent of living
species from any other living species : both these propositions are
errors of misapprehension or misrepresentation.

In order to understand the history of creation of a complex
being, it is necessary to analyze it and ascertain of what it con-
sists. In analyzing the construction of an animal or plant we
readily arrange its characters into those which it possesses in com-
mon with other animals or plants, and tliose in which it resem-
bles none other : the latter are its i7icUvidual characters, consti-
tuting its individuality. Next, we find a large body of characters,
generally of a very obvious kind, which it possesses in common
with a generally large number of individuals, which, taken col-
lectively, all men are accustomed to call a species ; these charac-
ters we consequently name specific. Thirdly, we find characters,
generally in parts of the body which are of importance in the ac-
tivities of the animal, or which lie in near relation to its mechan-
ical construction in details, which are shared by a still larger

130 GENERAL EVOLUTION.

number of individuals than those which were similar in specific
characters. In other words, it is common to a large number of
species. This kind of character we call generic^ and the grouping
it indicates is a genus.

Farther analysis brings to light characters of organism which
are common to a still greater number of individuals ; this we call
Si family character. Those which are common to still more nu-
merous individuals are the ordinal: they are usually found in
parts of the structure which have the closest connection with the
whole life-history of the being. Finally, the individuals compos-
ing many orders will be found identical in some important char-
acter of the systems by which ordinary life ic maintained, as in
the nervous and circulatory : the divisions thus outlined are called
classes.

By this process of analysis we reach in our animal or j^lant
those peculiarities which are common to the whole animal or vege-
table kingdom, and then we have exhausted the structure so com-
pletely that we have nothing remaining to take into account beyond
the cell-structure or homogeneous protoplasm by which we know
that it is organic, and not a mineral.

The history of the origin of a type, as species, genus, order,
etc., is simply the history of the origin of the structure or struct-
ures which define those groups respectively. It is nothing more
nor less than this, whether a man or an insect be the object of
investigation.

EVIDENCES OF DEEIVATION.

a. Of Specific Characters.

The evidences of derivation of species from species, within the
limits of the genus, are abundant and conclusive. In the first
place, the rule which naturalists observe in defining species is a
clear consequence of such a state of things. It is not amount and
degree of difference that determine the definition of species from
species, but it is the permanency of the characters in all cases and
under all circumstances. Many species of the systems include va-
rieties and extremes of form, etc., which, were they at all times
distinct, and not connected by intermediate forms, would be esti-
mated as species by the same and other writers, as can be easily
seen by reference to their works.

Thus, species are either "restricted " or '^protean," the latter

ON THE HYPOTHESIS OF EVOLUTION. 131

embracing many, the former few variations ; and the varieties in-
cluded by the protean species are often as different from each other
in their typical forms as are the ** restricted" species. As an ex-
ample, the species Homo sapiens (man) will suffice. His primary
varieties are as distinct as the species of many well-known genera,
but can not be defined, owing to the existence of innumerable in-
termediate forms between them.

As to the common origin of such '^varieties" of the protean
species, naturalists never had any doubt ; yet when it comes to the
restricted ^'^ species," the anti-developmentalist denies it in toto.
Thus the varieties of most of the domesticated animals are some
of them known — others held with great probability to have had a
common origin. Varieties of plumage in fowls and canaries are
of every-day occurrence, and are produced under our eyes. The
cart-horse and racer, the Shetland pony and the Norman, are
without doubt derived from the same parentage. The varieties of
pigeons and ducks are of the same kind, but not every one is
aware of the extent and amount of such variations. The varieties
in many characters seen in hogs and cattle, especially when exam-
ples from distant countries are compared, are very striking, and
are confessedly equal in degree to those found to define species in
a state of nature : here, however, they are not definitive.

It is easy to see that all that is necessary to produce in the
mind of the anti-developmentalist the illusion of distinct origin
by creation of many of these forms would be to destroy a number
of the intermediate conditions of specific form and structure, and
thus to leave remaining definable groups of individuals, and there-
fore "species."

That such destructions and extinctions have been going no
ever since the existence of life on the globe is well known. That
it should affect intermediate forms, such as bind together the
types of a protean species as well as restricted species, is equally
certain. That its result has been to produce definaUe species can
not be denied, especially in consideration of the following facts :
Protean species nearly always have a wide geographical distribu-
tion. Thev exist under more varied circumstances than do indi-
viduals of a more restricted species. The subordinate variations
of the protean species are generally, like the restricted species,
confined to distinct subdivisions of the geographical area which
the whole occupies. As in geological time changes of level have
separated areas once continuous by bodies of water or high mount-

132 GENERAL EVOLUTION.

ain-ranges, so have vast numbers of individuals occupying sucli
areas been destroyed. Important alterations of temperature, or
great changes in abundance or character of vegetable life over
given areas, would produce the same result.

This part of the subject might be prolonged, were it necessary,
but it has been ably discussed by Darwin. The rationale of the
^^ origin of species," as stated by him, may be examined a few
pages farther on.

p. Of the Characters of Higher Groups.

a. Relations of Structures. — The evidences of derivative origin
of the structures defining the groups called genera, and all those
of higher grade, are of a very different character from those dis-
cussed in relation to specific characters ; they are more diflScult of
observation and explanation.

First : It would appear to be supposed by many that the crea-
tion of organic types was an irregular and capricious process,
variously pursued by its Author as regards time and place, and
without definite final aim ; and this notwithstanding the wonder-
ful evidences we possess, in the facts of astronomy, chemistry,
sound, etc., of his adhesion to harmonious and symmetrical
sequences in his modes and plans.

Such regularity of plan is found to exist in the relations of the
great divisions of the animal and vegetable kingdoms as at present
existing on the earth. Thus, with animals we have a great class
of species which consists of nothing more than masses or cells of
protoplasmic matter, without distinct organs ; or the Protozoa.
We have then the Coelenterata (example, corals), where the organ- "
ism is composed of many cells arranged in distinct parts, but
where a single very simple system of organs, forming the only in-
ternal cavity of the body, does the work of the many systems of
the more complex animals. Next, the Echinodermata (such as
star-fish) present us with a body containing distinct systems of
organs inclosed in a visceral cavity, including a rudimental nerv-
ous system in the form of a ring. In the Molluscs to this con-
dition is added further complication, including extensions of
the nervous system from the ring as a starting-point, and a
special organ for a heart. In the Articulates (crabs, insects) we
have like complications, and a long distinct nervous axis on the
lower surface of the body. The last branch or division of ani-
mals is considered to be higher, because all the systems of life

ON" THE HYPOTHESIS OF EYOLUTIOX. 133

organs are most complex or specialized. The neryous rino- ig
almost obliterated by a great enlargement of its nsual gano-lja,
thus become a brain, which is succeeded by a long axis on the
upper side of the body. This and other points define the Ver-
tebrata.

Plans of structure, independent of the simplicity or perfection
of the special arrangement or structure of organs, also define
these great groups. Thus the Protozoa present a spiral, the
Coelenterata a radiate, the Echinodermata a bilateral radiate plan.
The Articulates are a series of external rings, each in one or more
respects repeating the others. The Molluscs are a sac, while a
ring above a ring, joined together by a solid center-piece, repre-
sents the plan of each of the many segments of the Vertebrates
which give the members of that branch their form.

These bulwarks of distinction of animal types are entered into
here simply because they are the most inviolable and radical of
those with which we have to deal, and to give the anti-develop-
mentalist the best foothold for his position. I will only allude to
the relations of their points of approach as these are affected by
considerations afterward introduced.

The Vertebrates approach the Molluscs closely at the lowest
extreme of the former and higher of the latter. The lamprey
eels of the one joossess several characters in common with the
cuttle-fish or squids of the latter. The amj)hioxus is called the
lowest Vertebrate, and, though it is nothing else, the definition of
the division must be altered to receive it ; it has no brain !

The lowest forms of the Molluscs and Articulates are scarcely
distinguishable from each other, so far as adhesion to the "plan "
is concerned, and some of the latter division are very near certain
Echinodermata. As we approach the boundary-lines of the two
lowest divisions, the approaches become equally close.

More instructive is the evidence of the relation of the subordi-
nate classes of any one of these divisions. The conditions of
those organs or parts which define classes exhibit a regular rela-
tion, commencing with simplicity and ending with complication ;
first associated with weak exhibitions of the highest functions of
the nervous system — at the last displaying the most exalted traits
found in the series.

For example : In the classes of Vertebrates we find the lowest
neryous system presents great simplicity — the brain can not be
recognized ; next (in lampreys), the end of the nervous axis is

134 GENERAL EVOLUTION.

subdivided, but scarcely according to the complex type that fol-
lows. In fishes the cerebellum and cerebral hemispheres are
minute, and the intermediate or optic lobes very large : in the
reptiles the cerebral hemispheres exceed the optic lobes, while the
cerebellum is smaller. In birds the cerebellum becomes complex
and the cerebrum greatly increases. In mammals the cerebellum
increases in complexity or number of parts, the o^^tic lobes
diminish, while the cerebral hemispheres become wonderfully
complex and enlarged, bringing us to the highest development,
in man.

The history of the circulatory system in the Vertebrates is the
same. First, a heart with one chamber, then one with two divis-
ions : three divisions belong to a large series, and the highest
possess four. The origins of the great artery of the body, the
aorta, are first five on each side : they lose one in the succeeding
class in the ascending scale, and one in each succeeding class or
order, till the Mammalia, including man, present us with but one
on one side.

From an infinitude of such considerations as the above, we
derive the certainty that the general arrangement of the various
grouj^s of the organic world is in scales, the subordinate within
the more comprehensive divisions. The identification of all the
23arts in such a complexity of organism as the highest animals
present is a matter requiring much care and attention, and con-
stitutes the study of homologies. Its pursuit has resulted in the
demonstration that every individual of every species of a given
branch of the animal kingdom is composed of elements common
to all, and that the differences which are so radical in the higher
groups are but the modifications of the same elemental parts,
representing completeness or incom^Dleteness, obliteration or sub-
division. Of the former character are rudimental organs, of
which almost every species possesses an example in some part of
its structure.

But we have other and still more satisfactory evidence of the
meaning of these relations. By the study of embryology we can
prove most indubitably that the simple and less complex are in-
ferior to the more complex. Selecting the Vertebrates again as
an example, the highest form of mammal — e. g., man — presents
in his earliest stages of embryonic growth a skeleton of cartilage,
like that of the lamprey ; he also possesses five origins of the
aorta and five slits on the neck : both which characters belong to

ox THE HYPOTHESIS OF EVOLUTION. 135

the lamprey and the shark. If the whole number of these parts
does not co-exist in the embryonic man, we find in embryos of
lower forms, more nearly related to the lamprey, that they do.
Later in the life of the mammal but four aortic origins are found,
which arrangement, with the heart now divided into two cham-
bers, from a beginning as a simple tube, is characteristic of the
class of Vertebrates next in order — the bony fishes. The optic
lobes of the human brain have also at this time a great predomi-
nance in size — a character above stated to be that of the same
class. With advancing development the infant mammal follows
the scale already pointed out. Three chambers of the heart and
three aortic origins follow, presenting the condition permanent
in the Batrachia ; and two origins, with enlarged cerebral hemi-
spheres of the brain, resemble the reptilian condition. Four
heart-chambers, and one aortic-root on each side, with slight
development of the cerebellum, follow, all characters defining the
crocodiles, and immediately precede the special conditions defin-
ing the mammals. These are, the single aorta-root from one
side, and the full development of the cerebellum ; later comes
that of the cerebrum also in its higher mammalian and human
traits.

Thus we see the order already pointed out to be true, and to
be an ascending one. This is the more evident as each type or
class passes through the conditions of those below it, as did the
mammal ; each scale being shorter as its highest terminus is
lower. Thus the crocodile passes through the stage of the lam-
prey, the fish, the batrachian, and the reptile proper.

h. In Time, — We have thus a scale of relations of existing
forms of animals and plants of a remarkable kind, and such as
to stimulate greatly our inquiries as to its significance. When
we turn to the remains of tlie past creation, preserved to us in
the deposits continued throughout geologic time, we are not
disappointed, for great light is at once thrown upon the sub-
ject.

We find, in brief, that the lowest division of the animal king-
dom appeared first, and long before any type of a higher charac-
ter was created. The Protozoon, Eozoon, is the earliest of
animals in geologic time, and represents the lowest type of
animal life now existing. We learn also that the highest branch
appeared last. No remains of Vertebrates have been found below
the lower Devonion period, or not until the Echinoderms and

136 GENERAL EVOLUTION.

Molluscs had reached a great pre-emmeuce. It is difficult to be
sure whether the Protozoa had a greater numerical extent in the
earliest periods than now, but there can be no doubt that the
Coelenterata (corals) and Echinoderms (crinoids) greatly exceeded
their present bounds in Paleozoic time, so that those at present
existing are but a feeble remnant. If we examine the sub-
divisions known as classes, evidence of the nature of the succes-
sion of creation is still more conclusive. The most poljp-like of
the Molluscs (Brachiopoda) constituted the great mass of its repre-
sentatives during Paleozoic time. Among Vertebrates the fishes
appear first, and had their greatest development in size and num-
bers during the earliest periods of the existence of the division.
Batrachia were much the largest and most important of land ani-
mals during the Carboniferous period, while the higher Verte-
brates were unknown. The later Mesozoic j^eriods saw the reign
of reptiles, whose position in structural develojoment has been
already stated. Finally, the most perfect, the mammal, came
upon the scene, and in his humblest rej^resentatives. In Tertiary
times Mammalia supplanted the reptiles entirely.

Thus the structural relations, the embryonic characters, and
the successive appearance in time of animals coincide. The same
is very probably true of plants.

That the existing state of the geological record of organic
types should be regarded as anything but a fragment is, from
our standpoint, quite preposterous. And, more, it may be as-
sumed with safety that when completed it will furnish us with
a series of regular successions, with but slight and regular in-
terruptions, if any, from the species which represented the sim-
plest beginnings of life at the dawn of creation, to those which
have displayed complication and power in later or in the present
periods.

For the labors of the paleontologist are daily bringing to light
structures intermediate between those never before so connected,
and thus creating lines of succession where before were only in-
terruptions. Many such instances might be adduced : two might
be selected as examiDles from American paleontology ; * i. e. , the

* Prof. Huxley, in the last anniversary lecture before the Geological Society
of London, recalls his opinion, enunciated in 1862, that "the positively-ascertained
truths of Paleontology " negative " the doctrines of progressive modification, which
suppose that modification to have taken place by a necessary progress from more to
less embryonic forms, from more to less generalized types, within the limits of the

ox THE HYPOTHESIS OF EVOLUTION. 137

near approach to birds made by the reptiles Laelaps and Megadac-
tylus, and the combination of characters of the old genera Ich-
thyosaurus and Plesiosaurus in the Polycotylus of Kansas.

We had no more reason to look for intermediate or connectino-
forms between such types as these than between any others of
similar degree of remove from each other with which we are ac-

period represented by the fossiliferous rocks ; that it shows no evidence of such
modification ; and, as to the nature of that modification, it yields no evidence what-
soever that the earlier members of any long-continued group were more generalized
in structure than the later ones."

Respecting this position, he says : " Thus far I have endeavored to expand and
enforce by fresh arguments, but not to modify in any important respect, the ideas
submitted to you on a former occasion. But when I come to the propositions re-
specting progressive modification, it appears to me, with the help of the new light
which has broken from various quarters, that there is much ground for softening
the somewhat Brutus-like severity with which I have dealt with a doctrine for the
truth of which I should have been glad enough to be able to find a good foundation
in 1862. So far indeed as the Invertebrata and the lower Vertebrata are concerned,
the facts and the conclusions which are to be drawn from them appear to me to re-
main what they were. For anything that as yet appears to the contrary, the earliest
known Marsupials may have been as highly organized as their living congeners ; the
Permian lizards show no signs of inferiority to those of the present day ; the laby-
rinthodonts can not be placed below the living salamander and triton ; the Devo-
nian ganoids are closely related to polypterus and lepidosiren."

To this it may be replied: 1. The scale of progression of the Vertebrata is
measured by the condition of the circulatory system, and in some measure by the
nervous, and not by the osseous : tested by this scale, there has been successional
complication of structure among Vertebrata in time. 2. The .question with the
evolutionist is, not what types have persisted to the present day, but the order in
which types appeared in time. 3. The Marsupials, Permian saurians, labyrintho-
donts, and Devonian ganoids are remarkably generalized groups, and predecessors of
types widely separated in the present period. 4. Prof. Huxley adduces many such
examples among the mammalian subdivisions in the remaining portion of his lect-
ure. 5. Two alternatives ai*e yet open in the explanation of the process of evolu-
tion : since generalized types, which combine the characters of higher and lower
groups of later periods, must thus be superior to the lower, the lower must (first) be
descended from such a generalized form by degradation ; or (second) not descended
from it at all, but from some lower contemporaneous type by advance ; the higher
only of the two being derived from the first-mentioned. The last I suspect to be
a true explanation, as it is in accordance with the homologous groups. This law
will shorten the demands of paleontologists for time, since, instead of deriving all
Reptilia, Batrachia, etc., from common origins, it points to the derivation of higher
Reptilia of a higher order from higher Reptilia of a lower order, lower Reptilia of
the first from lower Reptilia of the second ; finally, the several groups of the lowest
or most generalized order of Reptilia from a parallel series of the class below, or
Batrachia.

138 GENEPwAL EYOLUTIOK

quainted. And inasmucli as almost all groups, as genera, orders,
etc., which are held to be distinct, but adjacent, present certain
points of approximation to each other, the almost daily discovery
of intermediate forms gives us confidence to believe that the
pointings in other cases will also be realized.

y. Of Transitions.

The preceding statements were necessary to the comprehension
of the supposed mode of metamorphosis or development of the
various types of living beings, or, in other words, of the single
structural features which define them.

As it is evident that the groups of highest rank have had their
origin in remote ages, cases of transition from one to the other by
change of character can not be witnessed at the present day. We
therefore look to the most nearly related divisions, or those of the
lowest rank, for evidence of such change.

It is necessary to premise that embryology teaches that all the
species of a given branch of the animal kingdom (e. g., Verte-
brate, Mollusc, etc.) are quite identical in structural character at
their first appearance on the germinal layer of the yolk of the
parent Qgg. It shows that the character of the respective groups
of high rank api^ear first, then those of less grade, and last of all
those structures which distinguish them as genera. But among
the earliest characters which appear are those of the species, and
some of those of the individual.

We find the characters of different genera to bear the same re-
lation to each other that we have already seen in the case of those
definitive of orders, etc. In a natural assemblage of related genera
we discover that some are defined by characters found only in the
embryonic stages of others, while a second will present a perma-
nent condition of its definitive part, which marks a more ad-
vanced stage of that highest. In this manner many stages of the
highest genus a2:)pear to be represented by permanent genera in all
natural groups. Generally, however, this resmblance does not
involve an entire identity, there being some other immaturities
found in the highest genus at the time it presents the character
preserved in permanency by the lower, which the lower loses.
Thus (to use a very gross illustration) a frog at one stage of growth
has four legs and a tail ; the salamander always preserves four
legs and a tail, thus resembling the young frog. The latter is,
however, not a salamander at that time, because, among other

ON THE HYPOTHESIS OF EVOLUTION. 139

things, the skeleton is represented by cartilage only, and the sala-
mander's is ossified. This relation is therefore an imitation only,
and is called inexact ^parallelism.

As we compare nearer and nearer relations — i. e., the genera
which present fewest points of difference — we find the differences
between undeveloped stages of the higher and permanent con-
ditions of the lower to grow fewer and fewer, until we find numer-
ous instances where the lower genus is exactly the same as the
undeveloped stage of the higher. This relation is called that of
exact parallelism.

It must now be remembered that the permanence of a charac-
ter is what gives it its value in defining genus, order, etc., in the
eyes of the systematist. So long as the condition is permanent no
transition can be seen ; there is therefore no development. If the
condition is transitional, it defines nothing, and nothing is devel-
oped ; at least, so says the anti-developmentalist. It is the old
story of the settler and the Indian : ^^WiJl you take owl and I
take turkey, or I take turkey and you owl ? "

If we find a relation of exact parallelism to exist between two
sets of species in the condition of a certain organ, and the differ-
ence so expressed is the only one which distinguishes them as sets
from each other — if that condition is always the same in each set
— we call them two genera : if in any species the condition is va-
riable at maturity, or sometimes the undeveloped condition of the
part is persistent and sometimes transitory, the sets characterized
by this difference must be united by the systematist, and the whole
is called a single genus.

We know numerous cases where different individuals of the
same species present this relation of exact parallelism to each
other ; and, as we ascribe common origin to the individuals of a
species, we are assured that the condition of the inferior individual
is, in this case, simply one of repressed growth, or a failure to ful-
fill the course accomplished by the highest. Thus, certain species
of the salamandrine genus Amblystoma undergo a metamorphosis
involving several parts of the osseous and circulatory systems, etc.,
while half grown ; others delay it till fully grown ; one or two
species remain indifferently unchanged or changed, and breed in
either condition, while another species breeds unchanged, and has
never been known to complete a metamorphosis.

The nature of the relation of exact parallelism is thus explained
to be that of checked or advanced growth of individuals having a

140 GENERAL EVOLUTION.

common origin. The relation of inexact parallelism is readily ex-
plained as follows : With a case of exact 2^arallelism in the mind,
let the repression producing the character of form B parallelize
the latter with a stage of form A in which a second part is not
quite mature : we will have a slight want of correspondence be-
tween the two. Form B will be immature in but one point, the
incompleteness of A higher being seen in two points. If we
suppose the immaturity to consist in a repression at a still earlier
point in the history of the higher, the latter will be undeveloped
in other points also : thus, the spike-horned deer of South Amer-
ica have the horn of the second year of the North American genus.
They would be generically identical with that stage of the latter,
were it not that these still possess their milk dentition at two
years of age. In the same way the nature of the parallelisms seen
in higher groups, as orders, etc., may be a' counted for.

The theory of homologous groups furnishes important evidence
in favor of derivation. Many orders of animals (probably all,
when we come to know them) are divisible into two or more sec-
tions, which I have called homologous. These are series of genera
or families, which differ from each other by some marked charac-
ter, but whose contained genera or families differ from each other
in the same points of detail, and in fact correspond exactly. So
striking is this correspondence that were it not for the general and
common character separating the homologous series, they would
be regarded as the same, each to each. Now, it is remarkable that,
where studied, the difference common to all the terms of two ho-
mologous groups is found to be one of inexact parallelism, which
has been shown above to be evidence of descent. Homologous
groups always occupy different geographical areas on the earth's
surface, and their relation is precisely that which holds between
successive groups of life in the periods of geologic time.*

In a word, we learn from this source that distinct geologic
epochs co-exist at the same time on the earth. I have been forced
to this conclusion f by a study of the structure of terrestrial life,
and it has been remarkably confirmed by the results of recent
deep-sea dredgings made by the United States Coast Survey in the
Gulf Stream, and by the British naturalists in the North Atlantic.
These have brought to light types of Tertiary life, and of even

* The extinct family of the Nimravidas, which is homologous with the existing
family of Felidae, has been discovered since this was written. (Ed. 1886.)
f " Origin of Genera," pp. 70, 77, 79.

ON THE HYPOTHESIS OF EYOLUTIOK 141

the still more ancient Cretaceous periods, living at the present
day.* That this discovery invalidates in any wise the conclusions
of geology respecting lapse of time is an unwarranted assumption
that some are forward to make. If it changes the views of some
respecting the parallelism or co-existence of faunas in different
regions of the earth, it is only the anti-developmentalists whose
position must be changed.

For, if we find distinct geologic faunae, or epochs defined by
faunae, co-existing during the present period, and fading or merg-
ing into one another as they do at their geographical boundaries,
it is proof positive that the geologic epochs and periods of past
ages had in like manner no trenchant boundaries, but also passed
the one into the other. The assumption that the apparent inter-
ruptions are the result of transfer of life rather than destruction,
or of want of opportunities of preservation, is no doubt the true

one.

8. Rationale of Development.

a. In Characters of Higher Groups. — It is evident in the case
of the species in which there is an irregularity in the time of com-
pletion of metamorphosis, that some individuals traverse a longer
developmental line than those which remain more or less incom-
plete. As both accomplish growth in the same length of time, it
is obvious that it proceeds with greater rapidity in one sense in
that which accomplishes most ; its growth is said to be accelerated.
This phenomenon is especially common among insects, where the
females of perfect males are sometimes larvae or nearly so, or pupae,
or lack wings or some character of final development. Quite as
frequently, some males assume characters in advance of others,
sometimes in connection with a peculiar geographical range.

In cases of exact parallelism we reasonably suppose the cause
to be the same, since the conditions are identical, as has been
shown ; that is, the higher conditions have been produced by a
crowding back of the earlier characters and an acceleration of
growth, so that a given succession in order of advance has extended
over a longer range of growth than its predecessor in the same al-
lotted time. That allotted time is the period before maturity and
reproduction, and it is evident that as fast as modifications or
characters should be assumed sufficiently in advance of that pe-
riod, so certainly would they be conferred upon the offspring by

* Most of the deep-sea forms are, however, degenerate forms of existing orders.
(Ed. 1886.)

14:2 GENERAL EVOLUTION.

reproduction. The acceleration in the assumption of a character,
progressing more rapidly than the same in another character, must
soon produce^ in a type whose stages were once the exact parallel
of a permanent lower form, the condition of inexact parallelism.
As all the more comprehensive groups present this relation to each
other, we are compelled to believe that acceleration has been the
principle of their successive evolution during the long ages of ge-
ologic time.

Each type has, however, its day of supremacy and perfection
of organism, and a retrogression in these respects has succeeded.
This has no doubt followed a law the reverse of acceleration, which
has been called retardation. By the increasing slowness of the
growth of the individuals of a genus, and later and later assump-
tion of the characters of the latter, they would be successively lost.

To what power shall we ascribe this acceleration, by which the
first beginnings of structure have accumulated to themselves
through the long geologic ages complication and power, till from
the germ that was scarcely born into a sand-lance, a human being
climbed the complete scale, and stood easily the chief of the
whole ?

In the cases of species, where some individuals develop farther
than others, we say the former possess more growth-force, or
*' vigor," than the latter. We may therefore say that higher types
of structure possess more "vigor" than the lower. This, how-
ever, we do not know to be true, nor can we readily find means to
demonstrate it.

The food which is taken by an adult animal is either assimi-
lated, to be consumed in immediate activity of some kind, or
stored for future use, and the excess is rejected from the body.
We have no reason to suppose that the same kind of material
could be made to subserve the production of force by any other
means than that furnished by a living animal organism. The ma-
terial from which this organism is constructed is derived first from
the parent, and afterward from the food, etc., assimilated by the
individual itself so long as growth continues. As it is the activity
of assimilation directed to a special end during this latter period
which we suppose to be increased in accelerated develojoment, the
acceleration is evidently not brought about by increased facilities
for obtaining the means of life which the same individual possesses
as an adult. That it is not in consequence of such increased fa-
cilities possessed by its parents over those of the type preceding it

ON THE HYPOTHESIS OF EVOLUTION". 143

seems equally improbable when we consider that the characters in
which the parent's advance has appeared are rarely of a nature to
increase those facilities.

The nearest approach to an explanation that can be offered
appears to be somewhat in the following direction :

There is every reason to believe that the character of the
atmosphere has gradually changed during geologic time, and that
various constituents of the mixture have been successively re-
moved from it, and been stored in the solid material of the
earth's crust in a state of combination. Geological chemistry has
shown that the cooling of the earth has been accompanied by the
j)recipitation of many substances only gaseous at high tempera-
tures. Hydrochloric and sulphuric acids have been transferred
to mineral deposits or aqueous solutions. The removal of carbonic-
acid gas and the vapor of water has been a process of much slower
progress, and after the expiration of all the ages a proportion of
both yet remains. Evidence of the abundance of the former in
the earliest periods is seen in the vast deposits of limestone rock ;
later, in the prodigious quantities of shells which have been
elaborated from the same in solution. Proof of its abundance
in the atmosphere in later periods is seen in the extensive de-
posits of coal of the Carboniferous, Triassic, and Jurassic periods.
If the most luxuriant vegetation of the present day takes but fifty
tons of carbon from the atmosphere in a century, per acre, thus
producing a layer over that extent of less than a third of an inch
in thickness, what amount of carbon must be abstracted in order
to produce strata of thirty-five feet in depth ? No doubt it occu-
pied a long period, but the atmosphere, thus deprived of a large
proportion of carbonic acid, would in subsequent periods undoubt-
edly possess an improved capacity for the support of animal life.

The successively higher degree of oxidization of the blood in
the organs designed for that function, whether performing it in
water or air, would certainly accelerate the performances of all
the vital functions, and among others that of growth. Thus it
may be that acceleration can be accounted for, and the process of
the development of the orders and sundry lesser groups of the
Vertebrate kingdom indicated ; for, as already pointed out, the
definitions of such are radically placed in the different structures
of the organs which aerate the blood and distribute it to its
various destinations.

But the great question. What determined the direction of this

144 GENERAL EYOLUTIOK

acceleration ? remains unanswered. One can not understand why
more highly oxidized blood should hasten the growth of j)artition
of the ventricle of the heart in the serpent, the more perfectly to
separate the aerated from the impure fluid ; nor can we see why a
more perfectly constructed circulatory system, sending purer
blood to the brain, should direct accelerated growth to the cere-
bellum or cerebral hemispheres in the crocodile.

h. In Characters of the Specific Kind. — Some of the charac-
ters usually placed in the specific category have been shown to be
the same in kind as those of higher categories. The majority are,
however, of a different kind, and have been discussed several
pages back.

The cause of the origin of these characters is shrouded in as
much mystery as that of those which have occupied the pages im-
mediately preceding. As in that case, we have to assume, as
Darwin has done, a tendency in Nature to their production.
This is what he terms ^^the principle of variation." Against an
unlimited variation the great law of heredity or atavism has ever
been opposed, as a conservator and multiplier of type. This
principle is exemplified in the fact that like produces like — that
children are like their parents, frequently even in minutiae. It
may be compared to habit in metaphysical matters, or to that
singular love of time or rhythm seen in man and lower animals,
in both of which the tendency is to repeat in continual cycles a
motion or state of the mind or sense.

Further, only a proportion of the lines of variation is supposed
to have been perpetuated, and the extinction of intermediate
forms, as already stated, has left isolated groups or species.

The effective cause of these extinctions is stated by Darwin to
have been a "natural selection" — a proposition which distin-
guishes his theory from other development hypotheses, and w^hich
is stated in brief by the expression, "the survival of the fit-
test." Its meaning is this : that those characters appearing as
results of this spontaneous variation which are little adapted to
the conflict for subsistence, with the nature of the supply, or
with rivals in its pursuit, dwindle and are sooner or later ex-
tirpated ; while those which are adapted to their surroundings,
and favored in the struggle for means of life and increase, pre-
dominate, and ultimately become the centers of new variation.
"I am convinced," says Darwin, "that natural selection has
been the main, but not exclusive, means of modification."

ON THE HYPOTHESIS OF EVOLUTION. 145

That it has been to a large extent the means of preservation of
those structures known as specific, must, I think, be admitted.
They are related to their peculiar surroundings very closely, and
are therefore more likely to exist under their influence. Thus, if
a given genus extends its range over a continent, it is usually
found to be represented by peculiar species — one in a maritime
division, another in the desert, others in the forest, in the swamp
or the elevated areas of the region. The wonderful interdepend-
ence shown by Darwin to exist between insects and plants in the
fertilization of the latter, or between animals and their food-
plants, would almost induce one to believe that it were the true
expression of the whole law of development.

But the following are serious objections to its universal appli-
cation :

First : The characters of the higher groups, from genera up,
are rarely of a character to fit their possessors especially for sur-
rounding circumstances ; that is, the differences which separate
genus from genus, order from order, etc., in the ascending scale
of each, do not seem to present a superior adaptation to surround-
ing circumstances in the higher genus to that seen in the lower
genus, etc. Hence, superior adaptation could scarcely have
caused their selection above other forms not existing. Or, in
other words, the very differences in structure which indicate suc-
cessional relation, or which measure the steps of progress, seem to
be equally well fitted for their surroundings.

Second : The higher groups, as orders, classes, etc., have been
in each geologic period alike distributed over the whole earth,
under all the varied circumstances offered by climate and food.
Their characters do not seem to have been modified in reference
to these. Species, and often genera, are, on the other hand,
eminently restricted according to climate, and consequently vege-
table and animal food.

The law of development which we seek is indeed not that
which preserves the higher forms and rejects the lower after their
creation, but that which explains why higher forms were created
at all. Why in the results of a creation we see any relation of
higher and lower, and not rather a world of distinct types, each
perfectly adapted to its situation, but none properly higher than
another in an ascending scale, is the primary question. Given
the principle of advance, then natural selection has no doubt
modified the details; but in the successive advances we can
10

146 GENERAL EVOLUTION.

scarcely believe such a principle to be influential. We look
rather upon a progress as the result of the expenditure of some
force fore-arranged for that end.

It may become, then, a question whether in characters of high
grade the habit or use is not rather the result of the acquisition of
the structure than the structure the result of the encouragement
offered to its assumed beginnings by use, or by liberal nutrition
derived from the increasingly superior advantages it offers.

€. The Physical Origin of Man.

If the hypothesis here maintained be true, man is the de-
scendant of some 2^re-existent generic type, the which, if it were
now living, we would probably call an ape.

Man and the chimpanzee were in Linnseus's system only two
species of the same genus, but a truer anatomy places them in
separate genera and distinct families. There is no doubt, how-
ever, that Cuvier went much too far when he proposed to con-
sider Homo as the representative of an order distinct from the
Quadrumana, under the name of Bimana. The structural differ-
ences will not bear any such inter23retation, and have not the
same value as those distinguishing the orders of Mammalia ; as,
for instance, between Carnivora and bats, or the cloven-footed ani-
mals and the rodents, or rodents and edentates. The differences
between man and the chimpanzee are, as Huxley well puts it,
much less than those between the chimpanzee and lower Quadru-
mana, as lemurs, etc. In fact, man is the type of a family,
Hominidae, of the order Quadrumana, as indicated by the charac-
ters of the dentition, extremities, brain, etc. The reader who
may have any doubts on this score may read the dissections of
Geoffroy St. Hilaire, made in 1856, before the issue of Darwin's
'•'Origin of Species." He informs us that the brain of man is
nearer in structure to that of the orang than the orang's is to
that of the South American howler, and that the orang and
howler are more nearly related in this regard than are the howler
and the marmoset.

The modifications presented by man have, then, resulted from
an acceleration in development in some respects, and retardation
perhaps in others. But nntil the combination now characteristic
of the genus Homo was attained, the being could not properly be
called man.

And here it must be observed that as an organic type is char-

ON THE HYPOTHESIS OF EVOLUTION. 147

acterized by the co-existence of a number of peculiarities which
have been developed independently of each other, its distinctive
features and striking functions are not exhibited until that co-
existence is attained which is necessary for these ends.

Hence, the characters of the human genus were probably de-
veloped successively ; but few of the indications of human superi-
ority appeared until the combination was accomplished. Let the
opposable thumb be first perfected, but of what use would it be
in human affairs without a mind to direct ? And of what use a
mind without speech to unlock it ? xind speech could not be
possible though all the muscles of the larynx but one were devel-
oj^ed, or but a slight abnormal convexity in one pair of cartilages
remained.

It would be an objection of little weight could it be truly
urged that there have as yet no remains of ape-like men been dis-
covered, for we have frequently been called upon in the course of
paleontological discovery to bridge greater gaps than this, and
greater remain, which we expect to fill. But we have ape-like
characters exhibited by more than one race of men yet existing.

But the remains of that being which is supposed to have been
the progenitor of man may have been discovered a short time since
in the cave of Naulette, Belgium, with the bones of the extinct
rhinoceros and elephant.

We all admit the existence of higher and lower races, the latter
being those which we now find to present greater or less approxi-
mations to the apes. The peculiar structural characters that be-
long to the negro in his most typical form are of that kind, how-
ever great may be the distance of his remove therefrom. The
flattening of the nose and prolongation of the jaws constitute such
a resemblance ; so are the deficiency of the calf of the leg, and the
obliquity of the pelvis, which approaches more the horizontal po-
sition than it does in the Caucasian. The investigations made at
Washington during the war with reference to the physical charac-
teristics of the soldiers show that the arms of the negro are from
one to two inches longer than those of the whites : another ap-
proximation to the ape. In fact, this race is a species of the
genus Homo, as distinct in character from the Caucasian as those
we are accustomed to recognize in other departments of the ani-
mal kingdom ; but he is not distinct by isolation, since intermedi-
ate forms between him and the other species can be abundantly
found.

148 GENERAL EVOLUTION.

And here let it be particularly observed that two of the most
prominent characters of the negro are those of immature stages of
the Indo-European race in its characteristic types. The deficient
calf is the character of infants at a very early stage ; but, what is
more important, the flattened bridge of the nose and shortened
nasal cartilages are universally immature conditions of the same
parts in the Indo-European. Any one may convince himself of
that by examining the physiognomies of infants. In some races —
e. g., the Slavic — this undeveloped character persists later than in
some others. The Greek nose, with its elevated bridge, coincides
not only with assthetic beauty, but with developmental perfection.

This is, however, only ^^ inexact parallelism," as the charac-
ters of the hair, etc., can not be ex^^lained on this principle among
existing races. The embryonic characters mentioned are probably
a remnant of those characteristic of the primordial race or species.

.But the man of Naulette, if he be not a monstrosity, is a still
more distinct and ape-like species. The chin, that marked char-
acter of other species of men, is totally wanting, and the dentition
is quite approximate to the man-like apes, and different from that
of modern men. The form is very massive, as in apes. That he
was not abnormal is rendered probable by approximate characters
seen in a jaw from the cave of Puy-sur-Aube, and less marked in
the lowest races of Australia and New Caledonia.

As to the single or multiple origin of man, science as yet fur-
nishes no answer. It is very probable that, in many cases, the
species of one genus have descended from corresponding species of
another by change of generic characters only. It is a remarkable
fact that the orang possesses the peculiarly developed malar bones
and the copper color characteristic of the Mongolian inhabitants
of the regions in which this animal is found, while the gorilla ex-
hibits the prognathic jaws and black hue of the African races near
whom he dwells. This kind of geographical imitation is very
common in the animal kingdom.

II. METAPHYSICAL EVOLUTIOIT.

It is infinitely improbable that a being endowed with such ca-
pacities for gradual progress, as man has exhibited, should have
been full-fledged in accomplishments at the moment when he
could first claim his high title, and abandon that of his simian
ancestors. We are, therefore, required to admit the growth ot
human intelligence from a primitive state of inactivity and abso-

ON THE HYPOTHESIS OF EVOLUTION. 149

lute ignorance ; including the development of one important mode
of its expression — speech ; as well as that of the moral qualities,
and of man's social system — the form in which his ideas of moral-
ity are first displayed.

The expression '* evolution of morality" need not offend, for
the question in regard to the laws of this evolution is the really
important part of the discussion, and it is to the opposing views
on this point that the most serious interest attaches.

a. Development of Intelligence,

If the brain is the organ of mind, we may be surprised to find
that the brain of the intelligent man scarcely differs in structure
from that of the ape. Whence, then, the difference of power?
Though no one will now deny that many of the Mammalia are
capable of reasoning upon observed facts, yet how greatly the re-
sults of this capacity differ in number and importance from those
achieved by human intelligence ! Like water at the temperatures
of 50° and 53°, where we perceive no difference in essential char-
acter, so between the brains of the lower and higher monkeys no
difference of function or of intelligence is perceptible. But what
a difference do the two degrees of temperature from 33° to 31°
produce in water ! In like manner the difference between the
brain of the higher ape and that of man is accompanied by a dif-
ference in function and power, on which man's earthly destiny
depends. In development, as with the water, so with the higher
ape ; some Rubicon has been crossed, some floodgate has been
opened, which marks one of Nature's great transitions, such as
have been called ** expression-points" of progress.

What point of progress in such a history would account for
this accession of the powers of the human intelligence ? It has
been answered, with considerable confidence — the power of speech.
Let us picture man without speech. Each generation would learn
nothing from its predecessors. Whatever originality or observa-
tion might yield to a man would die with him. Each intellectual
life would begin where every other life began, and would end at a
point only differing with its original capacity. Concert of action,
by which man's power over the material world is maintained,
would not exceed, if it equaled, that which is seen among the
bees ; and the material results of his labors would not extend be-
yond securing the means of life and the employment of the sim-
plest modes of defense and attack.

150 GENERAL EVOLUTION.

The first men, therefore, are looked upon by tho develop-
mentalists as extremely embryonic in all that characterizes hu-
manity, and they appeal to the facts of history in support of this
yiew. If they do not derive much assistance from written his-
tory, evidence is found in the more enduring relics of human
handiwork.

The opposing view is, that the races which present or have
presented this condition of inferiority or savagery have reached it
by a process of degradation from a higher state — as some believe,
through moral delinquency. This position may be true in certain
cases, which represent perhaps a condition of senility, but in gen-
eral we believe that savagery was the condition of the first man,
which has in some races continued to the present day.

/?. Evidence from ArchcBology.

As the object of the present essay is not to examine fully into
the evidences for the theories of evolution here stated, but rather
to give a sketch of such theories and their connection, a few facts
only will be noticed.

Im'provement in the Use of Materials. — As is well known, the
remains of human handiwork of the earliest periods consist of
nothing but rude implements of stone and bone, useful only in
procuring food and preparing it for use. Even when enterprise
extended beyond the ordinary routine, it was restrained by the
want of proper instruments. Knives and other cutting imple-
ments of flint still attest the skill of the early races of men from
Java to the Cape of Good Hope, from Egypt to Ireland, and
through North and South America. Hatchets, spear-heads and
ornaments of serpentine, granite, silex, clay slates, and all other
suitable rock materials, are found to have been used by the first
men, to the exclusion of metals, in most of the regions of the
earth.

Later, the probably accidental discovery of the superiority of
some of the metals resulted in the substitution of them for stone
as a material for cutting implements. Copper — the only metal
which, while malleable, is hard enough to bear an imperfect edge
— was used by succeeding races in the Old World and the New.
Implements of this material are found scattered over extensive
regions. So desirable, however, did the hardening of the material
appear for the improvement of the cutting Q^ge, that combinations
with other metals were sought for and discovered. The alloy with

ON" THE HYPOTHESIS OF EVOLUTION. 151

tin, forming bronze and brass, was discovered and used in Enrojie,
while that with silver appears to have been most readily produced
in America, and was consequently used by the Peruvians and other
nations.

The discovery of the modes of reducing iron ores placed in
the hands of man the best material for bringing to a shape
convenient for his needs the raw material of the world. All im-
provements in this direction made since that time have been in
the quality of iron itself, and not through the introduction of any
new metal.

The prevalent phenomena of any given period are those which
give it its character, and by which we distinguish it. But this
fact does not exclude the co-existence of other phenomena belong-
ing to prior or subsequent stages. Thus during the many stages
of human progress there have been men more or less in advance
of the general body, and their characteristics have given a pecul-
iar stamp to the later and higher condition of the whole. It
furnishes no objection to this view that we find, as might have
been anticijoated, the stone, bronze, and iron periods overlapping
one another, or men of an inferior culture supplanting in some
cases a superior people. A case of this kind is seen in North
America, where the existing *^ Indians," stone-men, have suc-
ceeded the mound-builders, copper-men. The successional rela-
tion of discoveries is all that it is necessary to prove, and this
seems to be established.

The period at which the use of metallic implements was intro-
duced is unknown, but Whitney says that the language of the
Aryans, the ancestors of all the modern Indo-Europeans, indicates
an acquaintance with such implements, though it is not certain
whether those of iron are to be included. The dispersion of the
daughter races, the Hindoos, the Pelasgi, Teutons, Celts, etc.,
could not, it is thought, have taken j^lace later than 3000 b. c. —
a date seven hundred years prior to that assigned by the old chro-
nology to the Deluge. Those races co-existed with the Egyptian
and Chinese nations, already civilized, and as distinct from each
other in feature as they are now.

Improvement in Architecture. — The earliest periods, then, were
characterized by the utmost simplicity of invention and construc-
tion. Later, the efforts for defense from enemies and for architect-
ural display, which have always employed so much time and
power, began to be made. The megalithic period has left traces

152 GENERAL EVOLUTION.

over much of the earth. The great masses of stone piled on each
other in the simplest form in Southern India, and the circles of
stones planted on end in England at Stonehenge and Abury, and
in Peru at Sillustani, are relics of that period. More complex
are the great Himyaritic walls of Arabia, the works of the ances-
tors of the Phoenicians in Asia Minor, and the titanic workmanship
of the Pelasgi in Greece and Italy. In the iron age we find gra-
nitic hills shaped or excavated into temples ; as, for example,
everywhere in Southern India. Near Madura the circumference
of an acropolis-like hill is cut into a series of statues in high re-
lief, of sixty feet in elevation. Easter Island, composed of two
volcanic cones, one thousand miles from the west coast of South
America, in the bosom of the Pacific, possesses several colossi cut
from the intrusive basalt, some in high relief on the face of the
rock, others in detached blocks removed by human art from their
original positions and brought nearer the sea-shore.

Finally, at a more advanced stage, the more ornate and com-
plex structures of Central America, of Cambodia, Nineveh and
Egypt, represent the period of greatest display of architectural ex-
penditure. The same amount of human force has perhaps never
been expended in this direction since, though higher conceptions
of beauty have been developed in architecture with increasing in-
tellectuality.

Man has passed through the block-and-brick building period
of his boyhood, and should rise to higher conceptions of what is
the true disposition of power for " him who builds for aye," and
learn that *^ spectacle " is often the unwilling friend of j^rogress.

No traces of metallic implements have ever been found in the
salt-mines of Armenia, the turquoise-quarries in Arabia, the cities
of Central America, or the excavations for mica in North Carolina,
while the direct evidence points to the conclusion that in those
places flint was exclusively used.

The simplest occupations, as requiring the least exercise of
mind, are the pursuit of the chase and the tending of flocks and
herds. Accordingly, we find our first parents engaged in these
occupations. Cain, we are told, was, in addition, a tiller of the
ground. Agriculture in its simplest forms requires but little
more intelligence than the pursuits just mentioned, though no
employment is capable of higher development. If we look at the
savage nations at present occupying nearly half the land surface
of the earth, we shall find many examples of the former indus-

ON THE HYPOTHESIS OF EVOLUTION. I53

trial condition of our race preserved to the present day. Many
of them had no knowledge of the use of metals until they ob-
tained it from civilized men who visited them, while their pur-
suits were and are those of the chase, tending domestic animals,
and rudimental agriculture.

7. Development of the Fine Arts.

If we look at representation by drawing or sculpture, we find
that the efforts of the earliest races of which we have any knowl-
edge were quite similar to those which the untaught hand of in-
fancy traces on its .slate or the savage depicts on the rocky faces
of hills. The circle or triangle for the head and body, and
straight lines for the limbs, have been preserved as the first at-
tempts of the men of the stone period, as they are to this day tlie
sole representations of the human form which the North American
Indian places on his buffalo robe or mountain precipice. The
stiff, barely outlined form of the deer, the turtle, etc., are liter-
ally those of the infancy of civilized man.

The first attempts at sculpture were marred by the influence
of modism. Thus the idols of Cohan and Palenque, with human
faces of some merit, are overloaded with absurd ornament, and
deformed into frightful asymmetry, in compliance with the de-
mand of some imperious mode. In later days we have the stiff,
conventionalized figures of the palaces of Nineveh and the temples
of Egypt, where the representation of form has somewhat improved,
but is too often distorted by false fashion or imitation of some
unnatural standard, real or artistic. This is distinsfuished as the
day of archaic sculpture, which disappeared with the Etruscan
nation. So the drawings of the child, when he abandons the
simple lines, are stiff and awkward, and but a stage nearer true
representation ; and how often does he repeat some peculiarity or
absurdity of his own !

The introduction of the action and pose of life into sculpture
was not known before the early days of Greece, and it was there
that the art was brought to perfection. When art rose from its
mediaeval slumber, much the same succession of development may
be discovered. First, the stiff figures, with straightened limbs
and cylindric drapery, found in the old Northern churches — then
the forms of life that now adorn the porticoes and palaces of the
cities of Germanv.

154 GENERAL EVOLUTION.

d. Rationale of the Development of Intelligence.

The history of material development shows that the transition
from stage to stage of development, experienced by the most per-
fect forms of animals and plants in their growth from the primor-
dial cell, is similar to the succession of created beings which the
geological epochs produced. It also shows that the slow assump-
tion of main characters in the line of succession in early geological
periods produced the condition of inferiority, while an increased
rapidity of growth in later days has resulted in an attainment of
superiority. It is not to be supposed that in ^^acceleration" the
period of growth is shortened ; on the contrary, it continues the
same. Of two beings whose characters are assumed at the same
rate of succession, that with the quickest or shortest growth is
necessarily inferior. ^^Acceleration" means a gradual increase of
the rate of assumption of successive characters in the same period
of time. A fixed rate of assumption of characters, with gradual
increase in the length of the period of growth, would produce the
same result — viz., a longer developmental scale and the attainment
of an advanced position. The first is in part the relation of sexes
of a species ; the last of genera, and of other types of creation. If
from an observed relation of many facts we derive a law, we are
permitted, when we see in another class of facts similar relations,
to suspect that a similar law has operated, differing only in its ob-
jects. We find a marked resemblance between the facts of struct-
ural progress in matter and the phenomena of intellectual and
spiritual progress.

If the facts entering into the categories enumerated in the pre-
ceding section bear us out, we conclude that in the beginning of
human history the progress of the individual man was very slow,
and that but little was attained to ; that, through the profitable
direction of human energy, means were discovered from time to
time by which the process of individual development in all meta-
physical qualities has been accelerated ; and that up to the pres-
ent time the consequent advance of the whole race has been at an
increasing rate of progress. This is in accordance with the gen-
eral principle, that high development in intellectual things is
accomplished by rapidity in traversing the preliminary stages of
inferiority common to all, while low develo^oment signifies slug-
gishness in that progress, and a corresi^onding retention of in-
feriority.

ON THE HYPOTHESIS OF EVOLUTION. 155

How mucli meaning may we not see, from this standpoint,
in the history of the intelligence of our little ones ! First they
crawl, they walk on all-fours ; when they first assume the erect
position they are generally speechless, and utter only inarticulate
sounds. When they run about, stones and dirt, the objects that
first meet the eye, are the delight of their awakening powers ; but
these are all cast aside when the boy obtains his first jackknife.
Soon, however, reading and writing open a new world to him ;
and, finally, as a mature man he seizes the forces of Nature, and
steam and electricity do his bidding in the active pursuit of power
for still better and higher ends.

So with the history of the species : first, the quadrumane ;
then the speaking man, whose humble industry was, however,
confined to the objects that came first to hand, this being the
** stone age" of i^re-historic time. When the use of metals was
discovered, the range of industries expanded wonderfully, and the
*^iron age " saw many striking efforts of human power. With the
introduction of letters it became possible to record events and ex-
periences, and the spread of knowledge was thereby greatly in-
creased, and the delays and mistakes of ignorance correspondingly
diminished in the fields of the world's activity.

From the first we see in history a slow advance as knowledge
gained by the accumulation of tradition and by improvements in
habit based on experience ; but how slow was this advance while
the use of the metals was still unknown ! The iron age brought
with it not only new conveniences, but increased means of future
progress ; and here we have an acceleration in the rate of advance.
With the introduction of letters this rate was increased manifold,
and in the application of steam we have a change equal in utility
to any that has preceded it, and adding to the possibilities of fu-
ture advance in many directions. By it power, knowledge, and
means of happiness were to be distributed among the many.

The uses to which human intelligence has successively applied
the materials furnished by Nature have been — first, subsistence
and defense ; second, the accumulation of power in the shape of a
representative of that labor which the use of matter involves — in
other words, the accumulation of wealth. The possession of this
power involves new possibilities, for opportunity is offered for the
special pursuits of knowledge and the assistance of the weak or
undeveloped part of mankind in its struggles.

Thus, while the first men possessed the power of speech, and

156 GENERAL EVOLUTION.

could advance a little in knowledge through the accumulation of
the experiences of their predecessors, they possessed no means of
accumulating the power of labor, no control over the activity of
numbers — in other words, no wealth.

But the accumulation of knowledge finally brought this ad-
vance about. The extraction and utilization of the metals, espe-
cially iron, formed the most important step, since labor was thus
facilitated and its productiveness increased in an incalculable de-
gree. We have little evidence of the existence of a medium of ex-
change during the first or stone period, and no doubt barter was
the only form of trade. Before the use of metals, shells and other
objects were used ; remains of money of baked clay have been
found in Mexico. Finally, though in still ancient times, the pos-
session of wealth in money gradually became possible and more
common, and from that day to this avenues for reaching this stage
in social progress have ever been opening.

But wealth merely indicates a stage of progress, since it is but
a comparative term. All men could not become rich, for in that
case all would be equally poor. But labor has a still higher goal ;
for, thirdly, as capital, it constructs and employs machinery,
which does the work of many hands, and thus cheapens products,
which is equivalent in effect to an accumulation of wealth to the
consumer. And this increase of power may be used for the intel-
lectual and spiritual advance of men, or, otherwise, at the will of
the men thus favored. Machinery places man in the position of a
creator, operating on Mature through an increased number of
*' secondary causes."

Development of intelligence is seen, then, in the following
directions : First, in the knowledge of facts, including science ;
second, in language ; and, as consequences of these, the accumula-
tion of power by development — first, of means of subsistence ; and,
second, of mechanical invention ; and, third, in the apprehension
of beauty.

Thus, we have two terms to start with in estimating the be-
ginning of human development in knowledge and power : first,
the primary capacities of the human mind itself ; second, a mate-
rial world, whose infinitely varied components are so arranged as
to yield results to the energies of that mind. For example, the
transition-points of vaporization and liquefaction are so placed as
to be within the reach of man's agents ; their weights are so fixed
as to accord with the muscular or other forces which he is able to

ON THE HYPOTHESIS OF EVOLUTION. 157

exert ; and other living organizations are subject to his conven-
ience and rule, and not, as in previous geological periods, entirely
beyond his control. These two terms being given, it is maintained
that the present situation of the most civilized men has been at-
tained through the operation of a law of mutual action and reac-
tion— a law whose results, seen at the present time, have depended
on the acceleration or retardation of its rate of action ; which rate
has been regulated, according to the degree in which a third great
term, viz., the law of moral or (what is the same thing) true re-
ligious development, has been combined in the plan. What it is
necessary to establish in order to prove the above hypothesis is —

I. That in each of the particulars above enumerated the devel-
opment of the human species is similar to that of the individual
from infancy to maturity.

II. That from a condition of subserviency to the laws of mat-
ter, man's intelligence enables him, by an accumulation of power,
to become in a sense independent of those laws, and to pursue a
course of intellectual and spiritual progress.

III. That failure to accomplish a moral or spiritual develop-
ment will again reduce him to a subserviency to the laws of
matter.

This brings us to the subject of moral development. And here
I may be allowed to suggest that the weight of the evidence is
opposed to the philosophy, ^' falsely so called," of necessitarianism,
which asserts that the first two terms alone were sufficient to work
out man's salvation in this world and the next ; and, on the other
hand, to that anti-philosophy which asserts that all things in hu-
man progress, intellectual and moral, are regulated by immediate
divine interposition instead of through instrumentalities. Hence,
the subject divides itself at once into two great departments — viz.,
that of the development of mind or intelligence, and that of the
development of morality.

That these laws are distinct there can be no doubt, since in
the individual man one of them may produce results without the
aid of the other. Yet it can be shown that each is the most in-
valuable aid and stimulant to the other, and most favorable to
the rapid advance of the mind in either direction.

III. SPIRITUAL OR MORAL DEVELOPMENT.

In examining this subject, we first inquire (Section a) whether
there is any connection between physical and moral or religious

158 GENERAL EVOLUTION.

development ; then (/3), what indications of moral development
may be derived from history. Finally (y), a correlation of the
results of these inquiries, with the nature of the religious develop-
ment in the individual, is attempted. Of course in so stupendous
an inquiry but a few leading points can be presented here.

If it be true that the period of human existence on the earth
has seen a gradually increasing predominance of higher motives
over lower ones among the mass of mankind, and if any parts of
our metaphysical being have been derived by inheritance from
pre-existent beings, we are incited to the inquiry whether any of
the moral qualities are included among the latter ; and whether
there be any resemblance between moral and intellectual develop-
ment.

Thus, if there have been a physical derivation from a pre-
existent genus, and an embryonic condition of those physical
characters which distinguish Homo — if there has been also an
embryonic or infantile stage in intellectual qualities — we are led
to inquire whether the development of the individual in moral
nature will furnish us with a standard of estimation of the suc-
cessive conditions or present relations of the human species in
this aspect also.

a. Belations of Physical and Moral Nature.

Although, cmteris paribus, men are much alike in the deeper
qualities of their nature, there is a range of variation which is
best understood by a consideration of the extremes of such varia-
tion as seen in men of different latitudes, and women and chil-
dren.

{a) In Children. — Youth is distinguished by a peculiarity,
which no doubt depends upon an immature condition of the nerv-
ous center concerned, which might be called nervous impressi-
bility. It is exhibited in a greater tendency to tearfulness, in
timidity, less mental endurance, a greater facility in acquiring
knowledge, and more ready susceptibility to the influence of
sights, sounds, and sensations. In both sexes the emotional
nature predominates over the intelligence and judgment. In
those years the character is said to be in embryo, and theologians,
in using the phrase, '* reaching years of religious understanding,"
mean that in early years the religious capacities undergo develop-
ment coincidentally with those of the body.

{h) In Women. — If we examine the metaphysical characteris-

ON THE HYPOTHESIS OF EVOLUTION. 159

tics of women, we observe two classes of traits— namely, those
which are also found in men, and those which are absent or but
weakly developed in men. Those of the first class are very
similar in essential nature to those which men exhibit at an early
stage of development. This may be in some way related to the
fact that physical maturity occurs earlier in women.

The gentler sex is characterized by a greater impressibility,
often seen in the influence exercised by a stronger character, as
well as by music, color, or spectacle generally ; warmth of emo-
tion, submission to its influence rather than that of logic ; ti-
midity and irregularity of action in the outer world. All these
qualities belong to the male sex, as a general rule, at some period
of life, though different individuals lose them at very various
periods. Euggedness and sternness may rarely be developed in
infancy, yet at some still prior time they certainly do not exist in
any.

Probably most men can recollect some early period of their
lives when the emotional nature predominated — a time when
emotion at the sight of suffering was more easily stirred than in
maturer years. I do not now allude to the benevolence inspired,
kept alive, or developed by the influence of the Christian religion
on the heart, but rather to that which belongs to the natural
man. Perhaps all men can recall a period of youth when they
were hero-worshipers — when they felt the need of a stronger arm,
and loved to look up to the powerful friend who could sympathize
with and aid them. This is the ^* woman stage " of character : in
a large number of cases it is early passed ; in some it lasts longer ;
while in a very few men it persists through life. Severe disciiDline
and labor are unfavorable to its persistence. Luxury preserves its
bad qualities without its good, while Christianity j)reserves its
good elements without its bad.

It is not designed to say that woman in her emotional nature
does not differ from the undeveloped man. On the contrary,
though she does not differ in kind, she differs greatly in degree,
for her qualities grow with her growth, and exceed m poiver many
fold those exhibited by her companion at the original point of
departure. Hence, since it might be said that man is the unde-
veloped woman, a word of explanation will be useful. Embryonic
types abound in the fields of nature, but they are not therefore
immature in the usual sense. Maintaining the lower essential
quality, they yet exhibit the usual results of growth in individual

160 GENERAL EVOLUTION.

characters ; that is, increase of strength, powers of support and
protection, size and beauty. In order to maintain that the mas-
culine character coincides with that of the undeveloped woman,
it would be necessary to show that the latter during her infancy
possesses the male characters predominating — that is, unimpressi-
bility, judgment, physical courage, and the like.

If we look at the second class of female characters — nameh',
those which are imperfectly developed or absent in men, and in
respect to which man may be called undeveloped woman — we
note three prominent points : facility in language, tact or finesse,
and the love of children. The first two appear to me to be alto-
gether developed results of ^^impressibility," already considered
as an indication of immaturity. Imagination is also a quality of
impressibility, and, associated with finesse, is apt to degenerate
into duplicity and untruthfulness — a i^eculiarity more natural to
women than men.

The third quality is different. It generally appears at a very
early period of life. Who does not know how soon the little girl
selects the doll, and the boy the toy-horse or machine ? Here
man truly never gets beyond undeveloped woman. Nevertheless,
^^impressibility" seems to have a great deal to do with this
quality also.

Thus the metaphysical relation of the sexes would appear to
be one of inexact parallelism, as defined in Section I. That the
physical relation is a remote one of the same kind, several charac-
ters seem to point out. The case of the vocal organs will suffice.
Their structure is identical in both sexes in early youth, and botii
produce nearly similar sounds. They remain in this condition in
the woman, while they undergo a metamorjohosis and change both
in structure and vocal power in the man. In the same way, in
many of the lower creation, the females possess a majority of em-
bryonic features, though not invariably. A common example is
to be found in the plumage of birds, where the females and young
males are often undistinguishable.* But there are a few points in

* Meehan states that the upper limbs and stronc^ laterals in Coniferge and other
trees produce female flowers and cones, and the lower and more interior branches
the male flowers. He calls the former condition one of greater " vigor," and the
latter one of *' weakness," and argues that the vigorous condition of growth pro-
duces females, and the weaker males. What he points out, however, is in harmony
with the position here maintained — namely, that the female characters include more
of those which are embryonic in the males than the male characters include of those

ON THE HYPOTHESIS OF EVOLUTION. id

the physical structure of man also in which the male condition is
the immature one. In regard to structure, the point at which
the relation between the sexes is that of exact parallelism, or
where the mature condition of the one sex accords with the unde-
veloped condition of the other, is when reproduction is no longer
accomplished by budding or gemmation, but requires distinct
organs. Metaphysically, this relation is to be found where dis-
tinct individuality of the sexes first appears ; that is, where we
pass from the hermaphrodite to the bisexual condition.

But let us put the whole interpretation on this partial unde-
velopment of woman.

The types or conditions of organic life which have been the
most prominent in the world's history— the Ganoids of the first,
the Dinosaurs of the second, and the Mammoths of the third
period— have generally died with their day. The line of succes-
sion has not been from them. The law of anatom.y and paleon-
tology is, that we must seek the point of departure of the type
which is to predominate in the future, at lower stages on the line,
in less decided forms, or in what, in scientific parlance, are called
generalized types. In the same way, though the adults of the
tailless apes are in a physical sense more highly developed than
their young, yet the latter far more closely resemble the human
species in their large facial angle and shortened jaws.

How much significance, then, is added to the law uttered by
Christ ! — ^'Except ye become as little children, ye can not enter
the kingdom of heaven.'^ Submission of will, loving trust, con-
fiding faith — these belong to the child : how strange they appear
to the executing, commanding, reasoning man ! Are they so
strange to the woman ? We all know the answer. Woman is
nearer to the point of departure of that development which out-
lives time and j^eoples heaven ; and if man would find it, he must
retrace his steps, regain something he lost in youth, and join to

which are embryonic in the female : the female flowers are the product of the
younger and more growing portions of the tree — that is, those last produced (the
upper limbs and new branches) — while the male flowers are produced by the older
or more mature portions — that is, lower limbs or more axial regions. Further, we
are not accustomed to regard the condition of rapid growth as that of great vigor
in animals, but rather ascribe that quality to maturity, after such growth has
ceased.

Meehan's observations coincide with those of Thury and others on the origin
of sexes in animals and plants, which it appears to me admit of a similar explana-
tion.

102 GENERAL EVOLUTIOI^.

the powers and energies of his character the suhmission, love and
faith which the new birth alone can give.

Thus the summing up of the metaphj'sical qualities of woman
would be thus expressed : In the emotional world, man's superior ;
in the moral world, his equal ; in the laboring world, his inferior.

There are, however, vast differences in women in respect to
the number of masculine traits they may have assumed before be-
ing determined into their own special development. Woman also,
under the influence of necessity, in later years of life, may add
more or less to those qualities in her which are fully developed in
the man.

The relation of these facts to the principles stated as the two
opposing laws of development is, it apjDcars to me, to be exjolained
thus : First, that woman's most inherent peculiarities are not the
result of the external circumstances with which she has been
j)laced in contact, as the conflict theory would indicate. Such
circumstances are said to be her involuntary subserviency to the
physically more powerful man, and the effect of a compulsory
mode of life in preventing her from attaining a position of equali-
ty in the activities of the world. Second, that they are the result
of the different distributions of qualities as already indicated by
the harmonic theory of development ; that is, of the unequal posses-
sion of features which belong to different periods in the develop-
mental succession of the highest. There is then another beauti-
ful harmony which will ever remain, let the development of each
sex be extended as far as it may.

(c) In Men. — If we look at the male sex, we shall find various
exceptional approximations to the female in mental constitution.
Further, there can be little doubt that in the Indo-European race
maturity in some respects appears earlier in tropical than in
northern regions ; and though subject to many exceptions, this is
sufficiently general to be looked upon as a rule. Accordingly, we
find in that race — at least in the warmer regions of Europe and
America — a larger proportion of certain qualities which are more
universal in women ; as greater activity of the emotional nature
when compared with the judgment ; an impressibility of the nerv-
ous center, which, cmteris paribus, appreciates quickly the har-
monies of sound, form, and color ; answers most quickly to the
friendly greeting or the hostile menace ; is more careless of conse-
quences in the material expression of generosity or hatred, and
more indifferent to truth under the influence of personal relations.

ON THE HYPOTHESIS OF EVOLUTION. 1^3

The movements of the body and expressions of the countenance
answer to the temperament. More of grace and elegance in the
bearing marks the Greek, the Italian, and the Creole, than the
German, the Englishman, or the Green Mountain man. More of
vivacity and fire, for better or for worse, is displayed in the coun-
tenance.

Perhaps the more northern type left all that behind in its
youth. The rugged, angular character which appreciates force
better than harmony, the strong intellect which delights in fore-
thought and calculation, the less impressibility, reaching stolidity
in the uneducated, are its well-known traits. If there be in such
a character less generosity and but little chivalry, there is persist-
ency and unwavering fidelity, not readily obscured by the light-
ning of passion or the surmises of an active imagination.

All these peculiarities appear to result, first, from different de-
grees of quickness and depth in appreciating impressions from
without ; and, seco7id, from differing degrees of attention to the
intelligent judgment in consequent action. (I leave conscience
out, as not belonging to the category of inherited qualities.)

The above observations have been confined to the Indo-Euro-
pean race. It may be objected to the theory that savagery means
immaturity in the senses above described, as dependent largely on
"impressibility," while savages in general display the least '* im-
pressibility," as that word is generally understood. This can not
be asserted of the Africans, who, so far as we know them, possess
this peculiarity in a high degree. Moreover, it must be remem-
bered that the state of indifference which precedes that of impress-
ibility in the individual may characterize many savages ; while
their varied peculiarities may be largely accounted for by recol-
lecting that many combinations of different species of emotion
and kinds of intelligence go to make up the complete result in
each case.

(d) Conclusions. — Three types of religion may be selected
from the developmental conditions of man : first, an absence of
sensibility (early infancy) ; second, an emotional stage more pro-
ductive of faith than of works ; thirdly, an intellectual type, more
favorable to works than faith. Though in regard to responsibility
these states may be equal, there is absolutely no gain to laboring
humanity from the first type, and a serious loss in actual results
from the second, taken alone, as compared with the third.

These, then, are the physical vehicles of religion— \i the phrase

164 GENERAL EVOLUTION.

may be allowed — which give character and tone to the deeper
spiritual life, as the color of the transparent vessel is communi-
cated to the light which radiates from within.

But if evolution has taken place, there is evidently a provision
for the progress from the lower to the higher states, either in the
education of circumstances (^^ conflict ") or in the power of an in-
terior spiritual influence {'' harmony "), or both.

p. Evidence derived from History.

We trace the development of Morality in — first, the family, or
social order ; second, the civil order, or government.

Whatever may have been the extent of moral ignorance before
the Deluge, it does not appear that the earth was yet prepared for
the permanent habitation of the human race. All nations preserve
traditions of the drowning of the early peoples by floods, such as
have occurred frequently during geologic time. At the close of
each period of dry land, a period of submergence has set in, and
the depression of the level of the earth, and consequent overflow
by the sea, has caused the death and subsequent preservation of
the remains of the fauna and flora living upon it, while the eleva-
tion of the same has produced that interruption in the process of
deposit in the same region which marks the intervals between ge-
ologic periods. Changes in these respects do not occur to any very
material extent at the present time in the regions inhabited by the
most highly developed portions of the human race ; and as the
last which occurred seems to have been expressly designed for the
preparation of the earth's surface for the occupation of organized
human society, it may be doubted whether many such changes are
to be looked for in the future. The last great flooding was that
which stratified the drift materials of the north, and carried the
finer portions far over the south, determining the minor topogra-
phy of the surface and supplying it with soils.

The existence of floods which drowned many races of men may
be considered as established. The men destroyed by the one re-
corded by Moses are described by him as exceedingly wicked, so
that ^'i\\Q earth was filled with violence." In his ej-es the Flood
was designed for their extermination.

That their condition was evil must be fully believed if they
were condemned by the executive of the Jewish law. This law, it
will be remembered, permitted polygamy, slavery, revenge, ag-
gressive war. The Jews were expected to rob their neighbors, the

ON THE HYPOTHESIS OF EVOLUTION. 165

Egyptians, of jewels, and they were allowed *' an eye for an eye
and a tooth for a tooth." They were expected to butcher other
nations, with their women and children, their flocks and their
herds. If we look at the lives of men recorded in the Old Testa-
ment as examples of distinguished excellence, we find that their
standard, however superior to that of the people around them,
would ill accord with the morality of the present day. They were
all polygamists, slaveholders, and warriors. Abraham treated Ha-
gar and Ishmael with inhumanity. Jacob, with his mother's aid,
deceived Isaac, and received thereby a blessing which extended to
the whole Jewish nation. David, a man whom Paul tells us the
Lord found to be after his own heart, slew the messenger who
brought tidings of the death of Saul, and committed other acts
which would stain the reputation of a Christian beyond redemp-
tion. It is scarcely necessary to turn to other nations if this be
true of the chosen men of a chosen people. History, indeed, pre-
sents us with no people prior to, or contemporary with, the Jews
who were not morally their inferiors.*

If we turn to more modern periods, an examination of the mo-
rality of Greece and Rome reveals a curious intermixture of lower
and higher moral conditions. "While each of these nations pro-
duced excellent moralists, the influence of their teachings was not
sufficient to elevate the masses above what would now be regarded
as a very low standard. The popularity of those scenes of cruelty,
the gladiatorial shows and the combats with wild beasts, sufficiently
attests this. The Roman virtue of patriotism, while productive
of many noble deeds, is in itself far from being a disinterested
one, but partakes rather of the nature of partisanship and selfish-
ness. If the Greeks were superior to the Romans in humanity,
they were apparently their inferiors in the social virtues, and were
much below the standard of Christian nations in both resj^ects.

Ancient history points to a state of chronic war, in which tlie
social relations were in confusion, and the develoi3ment of the
useful arts was almost impossible. Savage races, which continue
to this day in a similar moral condition, are, we may easily be-
lieve, most unhappy. They are generally divided into tribes,
which are mutually hostile, or friendly only with the view of in-
juring some other tribe. Might is their law, and robbery, rapine.

* The evidence on this point being very imperfect, judgment may be properly
suspended. (Ed. 1886.)

166 GENERAL EYOLUTIOK

and murder express their mutual relations. This is the history of
the lowest grade of barbarism, and the history of primeval man so
far as it has come down to us in sacred and profane records. Man
as a species first appears in history as a sinful being. Then a race
maintaining a contest with tlie prevailing corruption and exhibit-
ing a higher moral idea is presented to us in Jewish history. Fi-
nally, early Christian society exhibits a greatly superior condition
of things. In it polygamy scarcely existed, and slavery and war
were condemned. But jorogress did not end here, for our Lord
said, *^I have yet many things to say unto you, but ye can not
bear them now. Howbeit, when he, the sj)irit of truth, is come,
he will guide you into all truth."

The progress revealed to us by history is truly great, and if a
similar difference existed between the first of the human sj^ecies
and the first of whose condition we have information, we can con-
ceive how low the oi'igin must have been. History begins with a
considerable progress in civilization, and from this we must infer
a long preceding period of human existence, such as a gradual
evolution would require.

y. Rationale of Moral Development,

I. Of the Species. — Let us now look at the moral condition of
the infant man of the present time. We know his small account-
ability, his trust, his innocence. We know that he is free from
the law that when he *^ would do good, evil is present with him,"
for good and evil are alike unknown. We know that until growth
has progressed to a certain degree he fully deserves the praise pro-
nounced by our Saviour, that "of such is the kingdom of heaven."
Growth, however, generally sees a change. We know that the
buddings of evil appear but too soon ; the lapse of a few months
sees exhibitions of anger, disobedience, malice, falsehood, and
their attendants — the fruit of a corruption within not manifested
before.

In early youth it may be said that moral susceptibility is often
in inverse ratio to physical vigor. But with growth the more
physically vigorous are often sooner taught the lessons of life, for
their energy brings them into earlier conflict with the antagonisms
and contradictions of the world. Here is a beautiful example of
the benevolent principle of compensation.

1. Innocence and the Fall. — If physical evolution be a reality,
we have reason to believe that the infantile stage of human mor-

ON THE HYPOTHESIS OF EVOLUTION. 157

als, as well as of human intellect, was much prolonged in the his-
tory of our first parents. This constitutes the period of human
purity, when we are told by Moses that the first pair dwelt in
Eden. But the growth to maturity saw the development of all
the qualities inherited from the irresponsible denizen of the forest.
Man inherits from his predecessors in the creation the buddino-s of
reason — he inherits passions, propensities, and appetites. His cor-
ruption is that of his animal progenitors, and his sin is the low
and bestial instinct of the brute creation. Thus only is the origin
of sin made clear — a problem which the pride of man would have
explained in any other way had it been possible.

But how startling the exhibition of evil by this new being as
compared with the scenes of the countless ages already past ! Then
the right of the strongest was God's law, and rapine and destruc-
tion were the history of life. But into man had been ^''breathed
the breath of life," and he had "■ become a Jiving soul." The law
of right, the Divine Spirit, was planted within him, and the laws
of the beast were in antagonism to that law. The natural devel-
opment of his inherited qualities necessarily brought him into col-
lision with that higher standard planted within him, and that war
was commenced which shall never cease "till he hath put all
things under his feet." The first act of man's disobedience con-
stituted the Fall, and with it would come the first intellectual
"knowledge of good and of evil" — an apprehension up to that
time derived exclusively from the divinity within, or conscience.*

2. Free Agency. — Heretofore development had been that of
physical types, but the Lord had rested on the seventh day, for
man closed the line of the physical creation. Now a new develop-
ment was to begin — the development of mind, of morality, and of
grace.

On the previous days of Creation all had progressed in accord-
ance with inevitable law apart from its objects. Now, two lines

* In our present translation of Genesis, the Fall is ascribed to the influence of
Satan assuming the form of the serpent, and this animal was cursed in consequence,
and compelled to assume a prone position. This rendering may well be revised,
since serpents, prone like others, existed in both America and Europe during the
Eocene epoch, five times as great a period before Adam as has elapsed since his day.
Clark states, with great probability, that "serpent" should be translated monkey or
ape — a conclusion, it will be observed, exactly comciding with our inductions on the
basis of evolution. The instigation to evil by an ape merely states inheritance in
another form. His curse, then, refers to the retention of the horizontal position re-
tained by all other quadrumana, as we find it at the present day.

168 GENERAL EVOLUTION.

of development were at the disposal of this being, between which
his free will was to choose. Did he choose the courses dictated
by the spirit of the brute, he was to be subject to the old law of
the brute creation — the right of the strongest and spiritual death.
Did he choose the guidance of the Divine Guest in his heart, he
became subject to the laws which are to guide — 1, tlie human spe-
cies to an ultimate ]3erfection, so far as consistent with this world ;
and, 3, the individual man to a higher life, where a new existence
awaits him as a spiritual being, freed from the laws of terrestrial
matter.

The charge brought against the theory of development, that
it implies a necessary progress of man to all perfection without his
co-operation — or necessitarianism, as it is called — is unfounded.

The free will of man remains 'the source alike of his j^i'ogress
and his relapse. But the choice once made, the laws of spiritual
development are apparently as inevitable as those of matter. Thus
men whose religious capacities are increased by attention to the
Divine Monitor within are in the advance of progress — progress
coinciding with that which in material things is called the har-
monic. On the other hand, those whose motives are of the lower
origin fall under the working of the law of conjlict.

The lesson derivable from the preceding considerations would
seem to be *^ necessitarian " as respects the whole human race, con-
sidered by itself ; and. I believe it is to be truly so interpreted.
That is, the Creator of 'all things has set agencies at work which
will slowly develop a perfect humanity out of his lower creation,
and nothing can thwart the jDrocess or alter the result. '' My word
shall not return unto me void, but it shall accomplish that which
I please, and it shall prosper in the thing whereto I sent it.^' This
is our great encouragement, our noblest hope — second only to that
which looks to a blessed inheritance in anotlier world. It is this
thought that should inspire the farmer, who, as he toils, wonders,
" Why all this labor ? The Good Father could have made me like
the lilies, who, though they toil not, neither spin, are yet clothed
in glory ; and why should I, a nobler being, be subject to the dust
and the sweat of labor ? " This thought should enlighten every
artisan of the thousands that people the factories and guide their
whirling machinery in our modern cities. Every revolution of a
wheel is moving the car of progress, and the timed stroke of the
crank and the rhythmic throw of the shuttle are but the music
the spheres have sung since time began. A new significance then

OiT THE HYPOTHESIS OF EVOLUTION. 169

appears in the prayer of David : '^ Let the beauty of the Lord our
God be upon us, and establish thou the work of our hands upon
us : the work of our hands, 0 Lord, establish thou it." But, be-
ware of the catastrophe, for '* He will sit as a refiner"; ''The
wheat shall be gathered into barns, but the chaff shall be burned
with unquenchable fire." If this be true, let us look for —

3. The Extinction of Evil. — How is necessitarianism to be
reconciled with free will ? It appears to me, thus : When a being
whose safety depends on the perfection of a system of laws aban-
dons the system by which he lives, he becomes subject to that
lower grade of laws which govern lower intelligences. Man, falling
from the laws of right, comes under the dominion of the laws of
brute force ; as said our Saviour, " Salt is good, but if the salt
have lost his savor, it is thenceforth good for nothing but to be
cast forth and trodden under foot of men."

In estimating the practical results to man of the actions
prompted by the lower i^ortion of our nature, it is only necessary
to carry out to its full development each of those animal qualities
which may in certain states of society be restrained by the social
system. In human history those qualities have repeatedly had
this development, and the battle of progress is fought to decide
whether they shall overthrow the system that restrains them, or
be overthrown by it.

Entire obedience to the lower instincts of our nature insures
destruction to the weaker, and generally to the stronger also. A
most marked case of this kind is seen where the developed vices of
civilization are introduced among a savage peo2:)le — as, for exam-
ple, the Korth American Indians. These seem in consequence to
be hastening to extinction.

But a system or a circuit of existence has been allotted to the
civil associations of the animal species man, independently of his
moral development. It may be briefly stated thus : Eaces begin
as poor offshoots or emigrants from a parent stock. The law of
labor develops their powers, and increases their wealth and num-
bers. These will be diminished by their various vices ; but, on
the whole, in proportion as the intellectual and economical ele-
ments prevail, wealth will increase — that is, they accumulate
power. When this has been accomplished, and before activity
has slackened its speed, the nation has reached the culminating
point, and then it enters upon the period of decline. The re-
straints imposed by economy and active occupation being removed.

170 GENERAL EVOLUTION.

the beastly traits find in accumulated power only increased means
of gratification, and industry and prosperity sink together. Power
is squandered, little is accumulated, and the nation goes down to
its extinction amid scenes of internal strife and vice. Its cycle is
soon fulfilled, and other nations, fresh from scenes of labor, as-
sault it, absorb its fragments, and it dies. This has been the
world's history, and it remains to be seen whether the virtues of
the nations now existing will be suflQcient to save them from a
like fate.

Thus the history of the animal man in nations is wonderfully
like that of the type or families of the animal and vegetable king-
doms during geologic ages. They rise, they increase, and reach a
period of multiplication and power. The force allotted to them
becoming exhausted, they diminish and sink and die.

II. Of the Individual. — In discussing physical development,
we are as yet compelled to restrict ourselves to the evidence of its
existence and some laws observed in the operation of its causative
force. What that force is, or what are its primary laws, we know-
not.

So, in the progress of moral development, we endeavor to prove
its existence and the mode of its operation, but why that mode
should exist, rather than some other mode, we can not explain.

The moral j)rogress of the species depends, of course, on the
moral progress of the individuals embraced in it. Eeligion is the
sum of those influences which determine the motives of men's
actions into harmony with the divine perfection and the divine
will.

Obedience to these influences constitutes the practice of religion,
while the statement of the growth and operation of these influences
constitutes the theory of religion, or doctrine.

The Divine Spirit j^lanted in man shows him that which is in
harmony with the Divine Mind, and it remains for his free will to
conform to it or reject it. This harmony is man's highest ideal of
happiness, and in seeking it, as well as in desiring to flee from
dissonance or pain, he but obeys the disposition common to all
conscious beings. If, however, he attemj)ts to conform to it, he
will find the law of evil present, and frequently obtaining the
mastery. If now he be in any degree observing, he will find that
the laws of morality and right are the only ones by which human
society exists in a condition superior to that of the lower animals,
and in which the capacities of man for happiness can approach a

ON THE HYPOTHESIS OF EVOLUTION. 171

state of satisfaction. He may be then said to be ^'awakened" to
the importance of religion. If he carry on the struggle to attain
to the high goal presented to his spiritual vision, he will be deeply
grieved and humbled at his failures ; then he is said to be '' con-
victed." Under these circumstances the necessity of a deliverance
becomes clear, and is willingly accepted in the only way in which
it has pleased the Author of all to present it, which has been epito-
mized by Paul as " the washing of regeneration and renewal of the
Holy Spirit through Jesus Christ." Thus a life of advanced and
ever-advancing moral excellence becomes possible, and the man
makes nearer approaches to the *' image of God."

Thus is opened a new era in spiritual development, which we
are led to believe leads to an ultimate condition in which the na-
ture inherited from our origin is entirely overcome, and an exist-
ence of moral perfection entered on. Thus, in the book of Mark
the simile occurs : ^^ First the blade, then the ear, after that the
full corn in the ear" ; and Solomon says that the development of
righteousness "shines more and more unto the perfect day."

8. Summary.

If it be true that general development in morality proceeds in
spite of the original predominance of evil in the world, through
the self-destructive nature of the latter, it is only necessary to ex-
amine the reasons why the excellence of the good may have been
subject also to progress, and how the remainder of the race may
have been influenced thereby.

The development of morality is then probably to be understood
in the following sense : Since the Divine Spirit, as the prime force
in human progress, can not in itself be supposed to have been in
any way under the influence of natural laws, its capacities were no
doubt as eternal and unerring in the first man as in the last. But
the facts and probabilities discussed above point to development
of religious sensiUlity, or capacity to appreciate moral good, or to
receive impressions from the source of good.

The evidence of this is supposed to be seen m— first, improve-
ment in man's views of his duty to his neighbor ; and, second, the
substitution of spiritual for symbolic religions : in other words,
improvement in the capacity for receiving spiritual impressions.

What the primary cause of this supposed development of re-
ligious sensibility may have been, is a question we reverently leave
untouched. Tliat it is intimately connected in some way with,

172 GENERAL EVOLUTION.

and in part dejoendent on, the evolution of tlie intelligence, appears
very probable ; for this evolution is seen — 'first, in a better under-
standing of the consequences of action, and of good and of evil in
many things ; and, second, in the production of means for the
spread of the special instrumentalities of good. The following
may be enumerated as such instrumentalities :

1. Furnishing literary means of record and distribution of the
truths of religion, morality, and science.

2. Creating and increasing modes of transportation of teachers
and literary means of disseminating truth.

3. Facilitating the migration and the spread of nations holding
the highest position in the scale of morality.

4. The increase of wealth, which multiplies the extent of the
preceding means.

And now, let no man attempt to set bounds to this develop-
ment. Let no man say even that morality accomplished is all that
is required of mankind, since that is not necessarily the evidence
of a spiritual development. If a man possess the capacity for prog-
ress beyond the condition in which he finds liimself, in refusing to
enter upon it he declines to conform to the divine law. For
*'from those to whom little is given, little is required, but from
those to whom much is given, much shall be required."

THE METHOD OF CREATION OF ORGANIC FORMS.

Chapter I — Ox the Law of Acceleration and Retardation. — !N"ature
of law of Natural Selection. Two kinds of evidence. Illustration.
Examples from Cervidae, HelicidaB, insects and men.

Chapter II — The Law of Repetitive Addition. — Segment and cell-
repetition. Illustration from limbs and vertebral column. A, On seg-
ment addition ; definitions. On repetition in bilateral and antero-pos-
terior symmetry ; in structure of compound teeth ; in segments of
Articulata; limbs of Reptilia ; brain of lain prey. B, On cell-repetition ;
simple segment a repetition of cells; simple diverticulum the same.
The cell theory ; the nucleated cell. C, Synthesis of repetition. From
unicellular to multicellular animals; simple repetition to compound
repetition ; Actinia, Lepidosiren, Ichthyosaurus, Plesiosaurus, Toenia ;
the heart; mammalian teeth. D, On growth-force; relation to other
forces; definition. E, Direction of repetition, its location, centrifugal
and longitudinal ; movements longitudinal. Inheritance ; its relation
to growth-force.

Chapter III — The Law of Use and Effort. — Points to be investigated.
A, On the location of growth-force. Relation of efi'ort to use. Rudi-
mental characters. Examples of growth under influence of physical
laws ; Examples of colors under influence of light. Use and disuse of
gills. Rattlesnake ; horned animals. Teeth of ruminants. B, Change
in amount of growth-force. Local increase of growth-force. Convo-
luted structures; brain, teeth, cotyledons. Absolute loss of growth-
force. Teeth and toes of Ruminants ; incisors of Rodents.

Chapter IY — On Grade Influence. — A, On the nature of Grade In-
fluence or Bathmism. Definitions. In plants; in animals. Increase
in time of Bathmism and growth-force. Vital forces and vital in-
fluences. Thought-force. Origin of Bathmism in time. B, Physio-
logical origin of Bathmism. Function of nervous system in force-
conversion. Automatic and habitual movements. Eflfect on nervous

system.
Chapter V — Intelligent Selection.— Development of intelligence. Stim-
uli to use. Compulsion, Choice ; Bees, Food, Rattlesnake ; Change of
color; Mimetic analogy ; Examples. Development of character.

In the present state of biological science, essays like the pres-
ent can only be tentative in so far as they treat of the laws of evo-

174 GENERAL EVOLUTION".

lution. Nevertheless the present time is pre-eminently one of
generalization in this field, and properly so. Facts have been ac-
cumulating for a long period, and are now sufficiently numerous
to yield important results, under proper classification and induc-
tion. Darwin led the way in this work, and the development
hypothesis is regarded as demonstrated by most biologists. The
discussion of the laws of its progress involves a multitude of
subordinate hypotheses. In the following essay, these are ar-
ranged under five prominent heads, viz. : 1. The law of Accelera-
tion and Eetardation; 2. The law of Repetitive Addition; 3. The
law of Use and Effort; 4. The law of Grade Influence; 5. The
law of Intelligent Selection. Of these, the first and second are
regarded by the author as demonstrated, the third and fourth as
only reduced to a partial demonstration, while the fifth is a con-
sequence of the third, and stands or falls with it.

The discussion of this subject divides itself into two parts,
viz. : a consideration of the proof that evolution of organic types
or descent with modification has taken place ; and, secondly, the
investigation of the laws in accordance with which this develop-
ment has progressed. As the latter involves the use of the evi-
dence included in the former, I will not devote a special chapter
to the proof for evolution.

The influences and forces which have operated to produce the
type structures of the animal kingdom have been plainly of two
kinds : 1. Originative ; 2. Directive. The prime importance of
the former is obvious ; that the latter is only secondary in the
order of time or succession is evident from the fact that it con-
trols the preservation or destruction of the results or creations of
the first, and thus furnishes the bases of the exhibitions of the
originative forces in the production of the successive generations
of living beings.

Wallace and Darwin have propounded as the cause of modifi-
cation in descent their law of natural selection. This law has
been epitomized by Spencer as the ''survival of the fittest."
This neat expression no doubt covers the case, but it leaves the
origin of the fittest entirely untouched. Darwin assumes a
''tendency to variation" in nature, and it is plainly necessary to
do this, in order that materials for the exercise of a selection
should exist. Darwin and Wallace's law is, then, only restrictive,
directive, conservative, or destructive of something already created.
I propose then to seek for the originative laws by which these sub-

THE METHOD OF CREATION OF ORGANIC FORMS. 175

jects are furnished — in other words, for the causes of the origin of
the fittest.

It has seemed to the author so clear from the first as to re-
quire no demonstration, that natural selection includes no ac-
tively progressive principle whatever ; that it must first wait for
the development of variation, and then, after securing the survival
of the best, wait again for the best to project its owm variations
for selection. In the question as to whether the latter are any
better or worse than the characters of the parent, natural selec-
tion m no wise concerns itself.

I. ON THE LAW OF ACCELEKATION" A:N"D RETAEDATIO]!^-.

There are two modes of demonstration of evolution, both de-
pending on direct observation. One of these has been success-
fully presented by Darwin. He has observed the origin of
varieties in animals and plants, either in the domesticated or
wild states, and has shown, what had been known to many, the
lack of distinction in the grades of difference which separate
varieties and species. But he has also pointed out that species
(such, so far, as distinctness goes) have been derived from other
species among domesticated animals, and he infers by induction
that other species, wiiose origin has not been observed, have also
descended from common parents. So far I believe his induction
to be justified ; but when from this basis evolution of divisions
defined by important structural characters, as genera, orders,
classes, etc., is inferred, I believe that we do not know enough of
the uniformity of Nature's processes in the premises to enable us
to regard this kind of proof as conclusive.

I therefore appeal to another mode of proving it, and one
which covers the case of all the more really structural features of
animals and plants.

It is well known that in both kingdoms, in a general way,
the young stages of the more perfect types are represented or imi-
tated with more or less exactitude by the adults of inferior ones.
But a true identity of these adults with the various stages of the
higher has, comparatively, rarely been observed. Let such a case
be supposed.

In A we have four species whose growth attains a given
point, a certain number of stages having been passed prior to its
termination or maturity. In B we have another series of four
(the number a matter of no importance), which, during the period

176 GENERAL EVOLUTION".

of growth, can not be distinguished by any common, i. e., generic
character, from the individuals of group A, but whose growth
has only attained to a point short of that reached by those of
group A at maturity. Here we have a parallelism, but no true
evidence of descent. But if we now find a set of individuals be-
longing to one species, or, still better, the individuals of a single
brood, and therefore held to have had a common origin or parent-
age, which present differences among themselves of the character

in question, we have gained a point.

-~ A We know in this case that the individ-
uals, a, have attained to the complete-
ness of character presented by group A,
while others, b, of the same parentage
have only attained to the structure of
those of group B. It is perfectly obvious
that the individuals of the first part of
the family have grown further, and, therefore, in one sense faster,
than those of group b. If the parents were like the individuals
of the more completely grown, then the offspring which did not
attain that completeness may be said to have been retarded in
their development. If, on the other hand, the parents were like
those less fully grown, then the offspring which have added some-
thing have been accelerated in their development.

I claim that a consideration of the uniformity of Nature's
processes, or inductive reasoning, requires me (however it may
affect the minds of others) to believe that the groups of species,
whose individuals I have never found to vary, but which differ in
the same point as those in which I have observed the above varia-
tions, are also derived from common parents, and the more ad-
vanced have been accelerated or the less advanced retarded, as the
case may have been with regard to the parents.

This is not an imaginary case, but a true representation of
many which have come under observation. The developmental
resemblances mentioned are universal in the animal, and probably
in the vegetable kingdoms, approaching the exactitude above de-
picted in proportion to the near structural similarity of the spe-
cies considered.

Example 1. — It is well known that the Cervidm of the Old
World develop a basal snag of the antler (see Cuvier, '' Ossemens
Fossiles," and Gray, " Oat. British Museum ") at the third year ; a
majority of those of the New World (genera Subulo, Cariacus)

THE METHOD OF CREATION OF ORGANIC FORMS. I77

never develop it except in abnormal cases in the most vio-orous
maturity of the most northern Cariacus [C. viryinianus), while
the South American Subulo retains to adult age the simple horn
or spike of the second year of all Cervidce»

Among the higher Gervidce^ Eusa and Axis never assume char-
acters beyond an equivalent of the fourth year of Cervus. In
Dama the characters are, on the other hand, assumed more rapidly
than in Cervus, its third year corresponding to the fourth of the
latter, and the development in after years of a broad plate of bone,
with points being substituted for the addition of the correspond-
ing snags, thus commencing another series which terminates in
the great fossil elk, Megacerus.

Returning to the American deer, we have Blastocerus, whose
antlers are identical with the fourth year of Cariacus. Corre-
sponding with the Dama-Megacerus type of the Old TVorld, we
have the moose (Alces) developing the same palmate horn- on the
basis of Cariacus (i. e., without eye-snag).

Example 2. — I select the following series, embracing the ma-
jority of the genera of the Korth American Helicidse.*

1. Turns of spire very few ; wide umbilicus ; shell thin, with thin W^s. . Binneya.

2. Turns few, but more ; rest as above Vitrina.

3. Turns still more numerous ; rest as above Hyalina.

4. As No. 3, but lip thickened inside Hygromia.

5. Coiled ; umbilicus closed ; lip thickened inside and out. . Tachea and Pomatia.

6. Same, with a parietal tootl^ Mesodon.

7. Same, with parietal and two interior lip teeth Isognomostoma.

* * Recommencing at Xo. 4. A.\\ ^iih. open umbilicus.

5. As No. 4, but lip thickened in and out Arionta.

6. Same as No. 5, but with parietal tooth Polymita .

T. Same, with both parietal and lip teeth Triodopsis.

The successional relation of these genera may be represented
in such a diagram as this :

Umbilicus open. Umbilicus closed.

Y * *

6 * *

5 * *

4 *

3 *

2 *

1 *

* See Tryon, *' Terrestrial Mollusca of the United States." Probably other (e. g.,
dental) characters distinguish some of these genera, but the above furnishes the
history of one set of characters.
12

178 GENERAL EYOLUTIOK

111 the history of the growth of the genera Isognomostoma and
Triodopsis, the extreme forms of the two series, it is well known
tliat at first the coils of the shell are extremely few, as in Binneya ;
and that, like it, it is very thin and with a delicately thin edge ;
that the turns increase successively in number, as in Vitrina and
Hyalina ; and that, finally, the lip thickens, as in Hygromia. Then
the umbilicus may close, as in Tachea, or (in Triodopsis) remain
open, as in Arionta. In either case a tooth is soon added on the
body-whorl (Polymita, Mesodon), and, finally, the full maturity
of the shell is seen in the added teeth of the inside of the lip-mar-
gin. How many of the stages of the genera Triodopsis and Meso-
don are identical with the genera of the series which represent
them, I leave to more thorough conchologists, but that some now
exhibit and all have once presented illustrations of the relation of
exact parallelism, I can not doubt.

Example 1. — An abundant race of the American deer, Caria-
cus virgiJiianus, exists in the Adirondack region of New York, in
which the development of the antlers never progresses beyond the
spike stage of the second year. Therefore, some individuals of
this species belong to Cariacus and some to Subulo. *

Example 2. — A large part of the individuals of the common
snail, Mesodon alhokibris, never develop the tooth of the body-
whorl, characteristic of the genus whose definition has to be modi-
fied to retain them.

Example 3. — Many individuals of Triodopsis tridentata from
eastern North Carolina occur withotit the lip-teeth, characteristic
of the genus Triodopsis. Hence these specimens, though of com-
mon origin with others of the species, must be referred to another
genus.

Example 4. — Structural characters are known in many, if not
all, species which are said to be *^ inconstant," being present or
absent indifferently, thus being useless for definition. They may
be rudimental when present or considerably developed. The pres-
ence or absence of wings in some species of insects may be cited ;
also the presence of generic characters in the male sex of many
Coleoptera and their absence in the females. The characters of

* Since the above was written the facts as stated have been denied. But the
author has seen specimens of Cariacus virgmianus and C. maa'oiis in which the
horns had assumed the characters of the genus Alces, throwing these individuals
into that genus. See "American Naturalist," 1883-'84. (Ed. 1886.)

THE METHOD OF CREATION OF ORGANIC FORMS. I79

males, females, workers and soldiers in bees and ants may be added.
All these facts belong to the same category as those cited among
deer and mollusks, and have a similar explanation.

Example 5. — It does not seem to be the law in '^retardation "
that parallelisms exhibited by the series in its rise to its highest
point of development should retrace the steps by which it attained
it, and that *' exact parallelisms " should be exhibited in a reversed
order. Parallelisms, it is true, are exhibited ; but so far as I have
observed always 'Mnexact," often in a high degree. A marked
case of retardation occurs in the dental development of a number
of persons who have come under my observation in the neighbor-
hood of Philadelphia. It is not very uncommon to find persons
in whom the third molars in both jaws are incomplete as to number,
one, two, three, or all, being deficient. It is still more common
for them to be incompletely covered by the enamel layer, and to
become in consequence so worthless as to require early removal. I
am acquainted with two families in which the absence of the ex-
terior upper incisor on each side is common. In one of these the
second and third generation have inherited it from the mother's
side, and it now characterizes many of the children. The signifi-
cance of this modification will be best understood by examining
the dental structures of the Qiiadrumana in general. Commencing
with the highest family and its abnormal dentition, w^e have :

Incisors. Canines. Premolars. Molars.

rr ■ '1 ( Abnormal. i i" f a — 2

( >iiormal. f 1 t t

Simiidce f \ I 3

Cebidce .... f "i- 3 f

LemuridcB f \ I — 3 3

Mammalia^ Normal | \ 4 I

In this table we see a decline in the number of teeth of the
higher groups. Thus, the premolars are one less than the normal
number in the whole order, and they lose one in each jaw in tlie
Old World apes, and man. The molars maintain the normal num-
ber throughout, but the third in both jaws is in the SimiidcB
reduced by the loss of a fifth or odd tubercle, thus becoming four-
lobed. In the upper jaw, this is first lost in the Semnopithecus ;
in the lower, in the next highest genus Cercopithecus. In Homo
its appearance is "retarded," the interval between that event and
the protrusion of the second molar— six to ten years— being rela-
tively greater than in any genus of Qiiadrumana. Its absence is

180 GENEPwAL EVOLUTION

then the result of continued retardation, not of a new and adaptive
suppression, and is of direct systematic zoological value.

In the incisors a reduction is also plainly visible, as we pass
from the most completely furnished mammals to the genus Homo.
One from the upper jaw is first lost, then, in the Cebidce, one from
the lower also. The number remains the same through the SimiidcB
and normal Hommidce, but, in the abnormal cases cited, the process
of reduction is continued and another incisor from each side disap-
pears. That this also is truly *^ retardation" is evident from the
fact, that the exterior incisor is the last developed, being delayed
in ordinary growth a year later than those of the inner pair. The
same retardation is seen in the quadrumane Cheiromys (the aye-
aye), and the whole order Rodentia. In the latter, the rare pres-
ence of the reduced second incisors, as in Lejjus, shows a less degree
of this modification. This retardation is also of systematic impor-
tance, and, should either of the characters described be constant in
any of the species of the genus Homo, would at once entitle it to
new generic rank. The very frequent absence of the posterior
molars (wisdom teeth) has been recently found to characterize a
race in India. Should this peculiarity prove constant, this race
would with propriety be referred to as a new genus of Hominidm,
as we have many cases of very similar species being referred to
different genera. It is altogether probable that such will, at some
future time, be the condition of some race or races of men.*

I am now disposed to regard the above as the method of produc-
tion, not only of generic but of all other, including specific char-
acters. It would appear that, by excessive acceleration or retarda-
tion, some of the characters of a series may be skipped; but observa-
tions are not conclusive on this point, since very close examination
is necessary for the appreciation of very transitory embryonic con-
ditions.

II. OK THE LAW OF REPETITIVE ADDITION.

The origin of new structures, which distinguish one generation
from those which have preceded it, I have stated to take place
under the law of acceleration. As growth (creation) of parts usu-
ally ceases with maturity, it is entirely plain that the process of
acceleration is limited to the period of infancy and youth in all
animals. It is also plain that the question of growth is one of

* The preceding section is merely an abbreviation, with new illustrations, of the
propositions brought forward in the writer's " Origin of Genera," 1868, where a con-
siderable extension of the subject will be found.

THE METHOD OF CREATION OF ORGANIC FORMS. 181

nutrition, or of the construction of organs and tissues out of pro-
toplasm.

The construction of the animal types may be referred to two
kinds of increase— the addition of identical segments and the addi-
tion of identical cells. The first is probably to be referred to the
last, but the laws which give rise to it can not now be explained.
Certain it is that segmentation is not only produced by addition of
identical parts, but also by subdivision of a homogeneous part. In
reducing the vertebrate or most complex animal to its simplest
expression, we find that all its specialized parts are but modifica-
tions of the segment, either simply or as sub-segments of compound
but identical segments. Gegenbaur has pointed out that the most
complex limb with hand or foot is constructed, first, of a single
longitudinal series of identical segments, from each of which a
similar segment diverges, the whole forming parallel series, not only
in the oblique transverse, but generally in the longitudinal sense.
Thus, the limb of the Lepidosiren represents the simple type, that
of the Ichthyosaurus a modification. In the latter, the first seg-
ment only (femur or humerus) is specialized, the other pieces being
undistinguishable. In the Plesiosaurian paddle the separate parts
are distinguished, the ulna and radius well marked, the carj^al
pieces hexagonal, the phalanges defined, etc.

As regards the whole skeleton, the same position may be safely
assumed. Though Huxley may reject Owen's theory of the verte-
brate character of the segments of the brain-case, because they are
so very different from the segments in other parts of the column,
the question rests entirely on the definition of a vertebra. If a
vertebra be a segment of the skeleton, of course the brain-case is
composed of vertebrae ; if not, then the cranium may be said to be
formed of ^'sclerotomes," or some other name mav be used. Cer-
tain it is, however, that the parts of the segments of the cranium
may be now more or less completely parallelized or homologized
with each other, and that, as we descend the scale of vertebrated
animals, the resemblance of these segments to vertebrae increases,
and the constituent segments of each become more similar. In the
types, as Amphioxus, etc., where the greatest resemblance is seen,
segmentation of either is incomplete, for they retain the original
non-osseous basis. Other animals which present cavities or parts
of a solid support are still more easily reduced to a simple basis of
segments, arranged either longitudinally (worm) or centrifugally
(star-fish, etc.).

182 GENERAL EVOLUTION.

DEFINITIONS.

a. The succession of construction of parts of a complex, was
originally a succession of identical repetitions ; and grade influ-
ence merely determined the number and location of such repeti-
tions.

(i. Acceleration signifies addition to the number of those repeti-
tions during the period preceding maturity, as compared with the
preceding generation, and retardation signifies a reduction of the
numbers of such repetitions during the same time.

y. The successive additions now characterizing the growth of the
highest animals are not exact repetitions of segments at this time,
because of influences brought to bear on cell-nutrition during long
periods. The nature of these influences is made the subject of
another section.

In the endeavor to prove these positions, I will produce evi-
dence, first, that some simpler animals grow according to the prin-
ciple of modified repetitive addition, and that traces of it are to be
observed in the most complex ; second, that every addition to
structure which has resulted in the complexity of the higher ani-
mals was originally a repetition of a pre-existent structure.

Detailed explanations of the law of repetitive addition are at-
tempted in the following pages, under two heads — segment-repeti-
tion, and cell-repetition.

A. On Segment- Repetition.

This is everywhere seen in the construction of animals and
plants. Double bilateral symmetry may serve as one example of
repetition in growth.

a. Bilateral symmetry. Anatomists have little diSiculty in de-
termining the bilateral symmetry in most animals — that is, the
homologies of the parts on opposite sides of the median line. It
might be almost asserted that it was a necessity of organization ;
but, when we observe the growth of many plants, we are unde-
ceived. And though bilateral symmetry in the Ccelenterata and
many Articulata is perfect, yet in higher animals it is more or less
departed from. In the Vertebrata the Amphioxus is almost com-
pletely bilaterally symmetrical. In the fishes, the digestive system
is the only one which does not conform to it ; while in the birds
the reproductive system is atrophied on one side. In the ser-
pents the respiratory and part of the circulatory are similarly

THE METHOD OF CREATION OF ORGANIC FORMS. 183

modified ; and in the Mammalia the digestive and circulatory
systems have both become unsymmetrical ; and the cranium, even
in the Cetacea.

If evolution be true, the unsymmetrical forms have descended
from the symmetrical, and the asymmetry being thus not inherited,
is the result of laws which have interfered with the original tend-
ency to bilateral repetition.

Many cases of bilaterally symmetrical diseases have been enu-
merated by physiologists, and I will select as an example one which
has come under my observation. They were those of two boys who
had had that disease involving the muco-dermal system called vari-
cella, while the crowns of the successional incisor teeth were still
inclosed in the mucous capsules of the alveolar walls. The deposit
of phosphate of lime forming their surfaces was interrupted by the
disease of the tissue, and the result was a surface pitted, or sculpt-
ured intaglio fashion. The sculpture of the two incisors of the
right side was precisely imitated by those of the left in reversed
order, even in minute details, which were numerous, thus produc-
ing a result not displeasing to the eye. This has been observed on
two distinct occasions some years apart.

Another interesting example of bilaterally symmetrical disease
is recorded in a paper on ^^ A Case of Universal Hyperostosis, etc.,"
by Drs. Mears, Keen, Allen, and Pepper.* They describe the skele-
ton of a boy of fourteen which displayed an extraordinarily exos-
tosed condition, the bones themselves remaining in the condition
known as osteoporosis. They describe the uniform repetition of
the abnormal growths of one side on the other in the following
language (p. 22) :

'^ Comparing the two sides externally, not only is there no dif-
ference in the extent and character of the disease, but there is the
most remarkable symmetry of the corresponding diseased bones,
which may be traced even into details. The disease begins and
ends on both sides at corresponding points, it changes in character
from simple porosity to the growth of osteophytes at corres])onding
points ; if, on one side, the posterior part of the bone is most dis-
eased, the same is true of the other side ; if the osteophyte growth
is continuous or interrupted on one bone (fibula, Fig. 18), it is so
on the opposite one ; if one is unusually diseased at a tendinous or
aponeurotic insertion, so is its mate ; if a groove or a variation in

* See "Proceed. Amer. Philos. Soc," 1810, p. 19.

184 GENERAL EVOLUTION.

color exist on the one side, the same will be found on the other
side ; even of single marked spiculae of bone the same may be said,
so that a description of one side will answer for both, minute dif-
ferences being noted as they occnr."

h. Anteroposterior symmetry.

That this is an absolute law of creation will be less readily ad-
mitted than in the case of double bilateral symmetry, since the ex-
ceptions appear to be so universal. Nevertheless, I believe it to be
as much a part of the law of repetitive nutrition as the other.
The anteroposterior homologies even of the human skeleton have
been largely demonstrated, bitt, as usual, we must appeal to the
lower forms for a clear view of it. In the rudimental skeletal axis
we find such symmetry almost perfect in the AmjoMoxus, but in no
other vertebrate. In limbs we have it clearly indicated in the
Eeptilian order Ichthyopterygia, and in the Piscine order Dipnoi,
where the anterior and posterior are scarcely or not at all distin-
guishable. In the scapular and pelvic arches we find it also ap-
proximated in the first-named orders.

In the nervous system it also exists approximately in the Am-
pMoxus. It is not seen in any vertebrate, and in but few other
animals, in the digestive system, but it appears to exist in some
lower Articulata in both the respiratory and circulatory systems.

c. As illustrations of exact repetition involving large portions
of the organism the higher Polyps may be cited, which differ from
the lower chiefly by the addition of similar septa and similar ten-
tacles. Examples of repetition of nearly the whole organism may
be found in many Entozoa, as Tmnia, where the cephalic segment
only differs from the others, the remainder or proglottides being
alike. The most entire repetition of structure is seen in Vibrio,
where the segments are all alike, there being none representing a
head.

d. As an example in special details of structure, the pelvic arch
of Ichthyosaurus, when first created, was a repetition of the scapu-
lar, and the hind limb, of the fore limb. The segments of the
limbs of the Dipnoi are mere repetitions, the later created of the
earlier. The special parts of the pes and manus of Ichthyosaurus
are simply repetitive efforts of growth-force joined with a dimin-
ishing amount. The addition of a digit, often distinguishing one
genus of Salamanders or Saurians from another, is evidence of a
similar repetitive effort. The low mammal Ornithorhynchus pos-
sesses but a single tooth in each jaw ; the simple teeth of armadil-

THE METHOD OF CEEATION OF ORGANTC FORMS. 185

los and cetaceans, increasing as they have done from a simpler
commencement, present examples of repetitiye acceleration of
growth-force.

e. Complication of a single element of repetition is accomplished
apparently by a double repetition. This is best understood by the
consideration of the transition from simple to complex teeth. In
the cetaceans this occurs in the Squalodonts ; the cylindric incisors
are followed by flattened ones, then by others grooved on the fang,
and then by two-rooted, but never double-crowned teeth. This is
the result of anteroposterior repetitive acceleration of the simple
cylindric dental type of the ordinary toothed cetacean.

Another mode of dental complication is by lateral repetition.
Thus, the heel of the sectorial tooth of a Carnivore is supported
by a fang alongside of the usual posterior support of a premolar,
and is the result of a repetitive effort of growth-force in a transverse
direction. More complex teeth, as the tubercular molars, merely
exhibit an additional lateral repetition, and sometimes additional
longitudinal ones. As is well known, the four tubercles of the
human molar commence as similar separate knobs on the dental
papilla.

The above are cited as examples to explain the meaning of the
proposition. When fuller demonstration is desired, a greater num-
ber might be given.

•

B. On Cell-Repetition.

That each additional act of creation in growth was originally
identical with one which preceded it, and therefore an exact repe-
tition in its character and results, is proved by the following con-
siderations.

It has been already determined by the study of homologies that
all organs and parts of an organism can be referred to an original
simple archetype.

The question then remains as to whether the first element, or
lowest term, of a given organized part is essentially a new struct-
ure, or whether it be a repetition of some previously existing one.
It may be asserted that the simplest expressions which shall cover
all organs are the solid segment, and the hollow sack, and tube.
For example, we have already noted that the ultimate element of
the limb is the first segment of the single ray of Lepidosiren. Is
this short cartilaginous cylinder (which probably represents the
fore limb of some undiscovered member of the Dipnoi) a result of

186 GENEKAL EVOLUTION.

the repetition of a pre-existent structural element ? This is no
doubt the case, for, as will be shown beyond, cartilage, though the
least cellular of all the tissues, is formed originally by cell repetition
or division. Again, the ultimate lobules of the most complex gland
are but repetitions of the diverticula of the simply branched, and
each of the latter repetitions of the simple cul-de-sac, which has
its origin in a convexity of an originally plane surface. This con-
vexity is again the result of repetition of cells or cell-division,
whereby their number is increased and the surface rendered
convex.

We are thus, in both the solid segment and hollow sack, brought
down to cell-repetition. Thus it is with organs, as with entire
animals, in which, following the line of simplification, we reach at
last forms composed of cells only {Act'mojjhrys, e. g.) and then
the unicellular (Amceba).

It this be the origin of organs, the question whether repetitive
growth has constructed tissues remains for consideration.

In growth, each segment — and this term includes the parts of
a complex whole or parts always undivided (as the jaw of a whale
or the sac-body of a mollusk) — is constructed, as is well known, by
cell-division. In the growing foetus the first cell divides its nucleus
and then its whole outline, and this process, repeated millions of
times, produces, according to the cell theory, all the tissues of the
animal organism or their bases, from first to last. That the ulti-
mate or histological elements of all organs are produced originally
by repetitive growth of simj^le nucleated cells, with various modifi-
cations of exactitude of repetition in the more complex, is taught
by the cell theory. The formation of some of the tissues is as fol-
lows :

First Change. — Formation of simple nucleated cells from ho-
mogeneous i^rotoplasm or the cytoblastema.

Second. — Formation of new cells by division of nucleus and body
of the old.

Third. — Formation of tissues by multiplication of cells with or
without addition of intercellular cytoblastema.

A. In connective tissue, by slight alteration of cells and addi-
tion of cytoblastema.

B. In blood, by addition of fluid cytoblastema (fibrin) to free
cells (lymph-corpuscles), which in higher animals (vertebrates) de-
velop into blood-corpuscles by loss of membrane, and by cell-devel-
opment of nucleus.

THE METHOD OF CREATION OF ORGANIC FORMS. 187

C. In muscles, by simple confluence of cells end to end, and
mingling of contents (Kolliker).

D. Of cartilage, by formation of cells in cytoblast which break
up, their contents being added to cytoblast ; this occurring seyeral
times, the result being an extensive cytoblast with few and small
cells (Vogt). The process is here an attempt at development with
only partial success, the result being a tissue of small vitality.

Even in repair-nutrition, recourse is had to the nucleated cell.
For Cohnhcim first showed that if the cornea of a frog's eye be
scarified, repair is immediately set on foot by the transportation
thither of white or lymph or nucleated corj^uscles from the neigh-
boring lymph-heart. This he ascertained by introducing aniline
dye into the latter. Repeated experiments have shown that this
is the history in great part of the construction of new tissues in
the adult man.

Now, it is well known that the circulating fluid of the foetus
contains for a period only these nucleated cells as corpuscles, and
that the lower vertebrates have a greater proportion of these corpus-
cles than the higher, whence probably the greater facility for repair
or reconstruction of lost limbs or parts enjoyed by them. The in-
vertebrates possess only nucleated blood-corpuscles.

C. Synthesis of Repetition.

That growth-force is capable of exhibiting great complexity of
movement with increase in amount, will now be shown. That this
quality of comiolication is one of its distinguishing features will
appear plain.

The simplest forms of life, as stated by Haeckel, are simply ho-
mogeneous drops of protoplasm {Protamoeha). These only grow
by ordinary accretion, and display a form of self division or repro-
duction which is the simplest possible — i. e., the bisection of the
mass by contraction at opposite points.

The next grade of animal type is represented by the nucleated
cell. This is simple in Amoeha, complex in Actinophrys, etc.
With such forms as the latter, cell-growth begins, and its develop-
ment is accomplished, by cell-division. This is simple repetition
of ultimate parts. In the growth of all higher types we have
nothing more than this, but following a law of complex repetition.
Thus in the growth of the parts of an archetypal vertebral column
or an archetypal limb, we have the repetition of cell-growth till
the first segment is formed, when it ceases at that point, and re-

188 GENERAL EVOLUTION.

peats the process again, forming another segment like the first ;
repetition within repetition. So with the construction of muscu-
lar tissue ; first, the nucleated cell repeated in a series, whose
adjacent walls disappear, and whose cell-contents flow together,
thus forming a fibrilla ; then a repetition of the same process,
forming a second fibrilla ; and so on to the completion of thou-
sands of them in fasciculi.

Let us then trace the series of repetitions and duplicated and
still more complex repetitions, seen in following up animal forms
from their archetypes.

In the simplest rejDetition of cell-growth in a longitudinal
direction we have Vibrio ; in the centrifugal, Actinophrys. The
former may be represented by a line of simple dots, thus : Fig. 1.

A.^... _.. ^

S.y" *V '

J Ci ao to aQOoa ^. ooQOococ3cCf cO ^3 O
f" o cjqOoc5 ^rs O oodODCD£i:n c:i> o ^^O,

In a complex repetition we rarely have the same degree of com-
plication in each repeated part. We have it centrifugally almost
perfect in a Coelenterate {Actinia), and linearly in some of the
lower vermes. An archetype of the latter kind might be repre-
sented thus : Fig. 2. In a more complex form, as of the pro-
glottides of TcBnia, thus : Fig. 3. The same might represent an
archetypal vertebrate.

If now we attempt to express the complication of an organ by
modified repetition of once identical parts, the history of extremi-
ties will serve us. Thus the limb of Lepidosiren, which is com-
posed of identical segments, may be thus represented : Fig. 2.
Each longitudinal segment of the limb of Ichthyosaurus may be
similarly represented with a modification, in size only, of the
proximal or humerus ; thus : Fig. 4. But in Plesiosatirus an
important series of changes of shape (but not in complexity) ap-
pears, which may be represented thus : Fig. 5 ; the first being

THE METHOD OF CREATION OF ORGANIC FORMS.. 189

humerus, second ulna, third and fourth carpals (tarsals), the last
phalanges, which are first specialized in this genus.

By far the most usual modification is, however, complication bv
duplicated and triplicated and still more highly multiplied repeti-
tion in some segments of the archetype, and its omission in other
segments. Thus in the Tcenia, the cejihalic segments are much
modified, and the nature of the repetition might be thus ex-
pressed : Fig. 6 ; the simpler segments representing the body
segment, the two complex representing those of the head. In
each, it will be observed, the complication is represented by loops
of similar form, and each loop of dots which represent the cells in
the first linear (Fig. 1) arrangement.

A somewhat similar figure might represent the nature of the
complication in the Myriapod. In the insect the additional com-
plications of the thoracic segments would alter the diagram near
the middle.

In the vertebrate cranium a somewhat similar diagram might
be used, except that the modification of the segments or vertebrae,
as compared with the segments of the vertebral column, is not by
rciDctition with modification of the parts of each segment, but
rather by modification of the forms of the parts of the segments.
The basicranial segments thus compare with the dorsal vertebrae
as the segments of the limb of Plesiosaurus do with those of Ich-
thyosaurus.

The above considerations have reference to repetition of parts
in a linear direction. Centrifugal repetition is seen in the addi-
tion of chambers to the heart, by the subdivision in the earliest
stages into auricle and ventricle in the linear direction, con-
sidered in connection with the earlier division of each in the
transverse direction by the growth of partitions. This mode of
repetitive addition is not readily represented by diagram.

A good example of repetitive addition, in both linear and
transverse direction, may be found in the successive complication
of tooth structure seen in Mammalia. In the dolphin, the dental
series may be represented thus : Fig. 7 ; in the squalodon thus :
Fig. 8 ; in the cat : Fig. 9 ; in the dog : Fig. 10 : in man : Fig.
11 ; in some Insectivora : Fig. 12.

The circles represented here are each a simple cusp.

In conclusion, the directions of repetitive growth may be
tabulated as follows : The types to the left represent the original ;
to the right, the derivative :

190 GENERAL EVOLUTION.

Centrifugal.

' More bilaterally { n ^ ^.'^ ^. ^
symmetrical. '] Only bilateral.

Longitudinal antero-pos- -<
terior and bilateral.

More antero-pos- j Only antero-
teriorly. ( posterior.

( In plane.
Centrifugal. •<

( In globe.

D. On Growtli-Force.

From such examples as those that precede, but more especially
from the last, it seems necessary to believe that there resides in
organized matter, and in its most unmodified representative, the
nucleated cell, an affection which displays itself in repetition.
This phenomenon reduced to its lowest terms, may mean cell-divis-
ion only, but the proof is only clear in cases of gi'owth proper.
This affection displays itself in very slow or more rapid repetitions
— cell-division in growth occurring rapidly, while its recurrences
at rutting seasons in the development of horns, feathers, etc., are
separated by long intervals of time. In acceleration these repeti-
tions occur with increased rapidity, i. e., in the adding of more
structures during the same growth periods, while in low types its
repetitions are few and therefore slow.

What is the relation of cell-division to the forces of nature, and
to which of them as a cause is it to be referred, if to any ? The
animal organism transfers solar heat and the chemism of the food
(protoplasm) to correlated amounts of heat, motion, electricity,
light (phosphorescence), and nerve force. But cell-division is an
affection of protoplasm distinct from any of these ; although addi-
tion to homogeneous lumps or parts of protoplasm (as in that low-
est animal, Protamceha of Hseckel) should prove to be an exhibi-
tion of mere molecular force, or attraction, cell-division is certainly
something distinct. It looks like an exhibition of another force,
which may be called groiuth-force. It is correlated to the other
forces, for its exhibitions cease unless the protoplasm exhibiting it
be fed.

Professor Henry i^ointed out many years ago that this must be
the case, basing his belief on the observed phenomena of growth in
the potato, and in the Qgg. The starch of the potato weighs much
more than the young shoot of cellulose, etc., into which it has been
converted by growth-activity, so that a portion of the substance
of the tuber has evidently escaped in some other direction. This

THE METHOD OF CREATION OF ORGANIC FORMS. 191

is shown to be carbonic acid gas and water, derived from the slow
combustion of the starch, which in thus running down from the
complex organic state to the more simple inorganic compounds,
evolves an amount of force precisely equal in amount to the chemi-
cal force (or chemism) requisite to bind together the elements in
the more complex substance.*

Carpenter also states that in his opinion the growth of the Funo-i
is produced by a force liberated by the retrograde metamorpliosts
of their food, which is of an organic character (i. e., humus).
This metamorphosis consists, as in the tuber, in the production of
carbonic acid gas and water, and a force equivalent to the chemism
which had bound them in the former complex union, f But in
higher forms of vegetable life, and in growth that follows germina-
tion, the plant must appropriate carbon from the carbonic acid of
the atmosphere. The decomposition of the binary compound
(which sets free its oxygen) liberates the chemical force which luid
previously maintained the compound (or an equivalent force), which
Henry regards as furnishing the growth-force, which produces the
plant. Carpenter derives but a portion of the force in this way,
obtaining the greater part from the heat of the sun. To this source
also he looks for the heat necessary to the construction of cold-
blooded animals ; while in warm-blooded animals, the retrograde
metamorphosis or running down of the material (protoplasm) of
the food furnishes a requisite amount of heat.

Growth-force we may then regard as potential in organized tis-
sue, and as energetic during growth. J; Our present knowledge

* "Agricultural Report of the Patent Office," ISSY.

•(• " Correlation of Physical and Vital Forces," 1864 (" Quarterly Jour, of Science ").

j: Bathmism or growth-force must be static or potential in each unit or plastid
(cell) of a living organism, the type differing with each organic species. When it is
in excess in a given locality it becomes energetic, and builds tissue in various forms.
A portion of this energy is, in this process, developed as molar motion of nutritive
material, and is accompanied in the completed structure by the ordinary cohesive
energy, by which the newly-built material maintains its attachment as a whole and
in its parts. If living tissue be constructed, a portion of the excess remains as the
static energy of the plastids or cells of the new part, as it did of the old. The
spermatozoid is highly endowed with static bathmism, and communicates it to the
female ovum. The mingling of the two elements in the presence of nutritious ma-
terial presents an excess, and form-building results. Its activity will regulate sub-
sequent new growth, by giving the motion of nutritive material its proper direc-
tion. When the tissue dies, this energy must leave behind a dynamic equivalent,
but what this may be is as yet a mystery. (Ed. 1886.)

192 ^ GENERAL EVOLUTION".

only permits us to believe that other force is only conA^erted into
it under the influence of pre-existent life, but of the real cause of
this conversion we are as ignorant as in the case of the physical
forces.

In the animal organism, different tissues display different de-
grees of ^^ vitality." The most vital display cell-organization and
its derivative forms, while the least so, approach nearer to homo-
geneity. As organized tissue is the machine for converting vital
forces, we may believe that less growth-force is potential as such in
cartilage than in muscle, for it is formed by a retrograde process,
by which cells once formed are mostly lost, and the contents form
the intercellular, nearly structureless mass characteristic of this
tissue. Growth-force must be here liberated in some other form,
perhaps the mere cohesive force of the former or ^^ dead" inter-
cellular substance.

The higher vitality we may believe to result from the greater
perfection of the more complex tnacliine as a force converter, as
compared with the ineiSiciency of the more simple.

E, On the Diredioii of Repetition,

It has been already pointed out ihoi groiutli-force exhibits itself
in cell or segment re^Dctition. The forms in which it thus displays
itself may be briefly considered. The approximate cause is treated
of in the next chapter ; but enough may be shown here to indicate
that duplication and complex duplication is the law of growth-force,
and that therefore this process must always follow an increase in
a7nount in any given locality.

The size of a part is then dependent on the amount of cell-divis-
ion or growth-force, which has given it origin, and the number
and shape of segments is due to the same cause. The whole ques-
tion, then, of the creation of animal and vegetable types is reduced
to one of the amount and location of groiuth-force.

Repetition is of two kinds, centrifugal and longitudinal. As
an example of the former, the genus Actinoplirys has been cited,
where the animal is composed of cells arranged equidistally around
a common center. The arrangement in this type may be dis-
coidal or globular, providing no definite axis be discoverable. As
an example of longitudi^ial repetition. Vibrio, and numerous
cellular plants may be cited, where the arrangement is in a single
line.

In by far the greater number of animals these kinds of repeti-

THE METHOD OF CREATION OF ORGANIC FORMS. I93

tive structure co-exist. The loyigitudinal is, however, predomi-
nant in the Vertedrata, Mollusca, and Articulata, while the cen-
trifugal is greatly developed in the Ooelenterata and Radiata. In
none but the simplest forms are either of these modes to be found
alone.

The centrifugal repetition, or addition, more nearly resembles
the mode of aggregation of atoms in inorganic or crystalline
bodies, and hence may be regarded as the inferior manifestation.
It implies that growth-force in this case conforms to a law of
polarity in exhibiting itself at equal distances from a center —
which is allied to ordinary molecular force, and independent of
the localizing influences of which higher organisms seem capable.
In centrifugal animals, then, the latter evidently plays an in-
ferior part. In Coelenterates and Radiates, however, the body
possesses a short longitudinal axis, in some (Asterias) very short,
in others (Holothuria) more elongate. The amount of com-
plication of centrifugal growth greatly exceeds the complication
in a longitudinal direction in all of these animals except the
Holothurida.

It is now important to observe that great numbers of centrifu-
gal animals are sedentary or sessile ; while the longitudinal are
vagrant, moving from place to place. Many of the centrifugal
animals which wander, do not do so in the direction of their axis,
but sideways {Medusce). It is also proper to notice that not only
the movements of the muscles but also the direction taken by
the food is in the long axis. It is therefore to be concluded that
in longitudinal animals growth-force has assumed a more truly
animal type, and that this tendency has predominated over the
polar or molecular tendency.

In most longitudinal animals, however, certain lateral portions,
limbs, etc., extend on each side of the axis ; and were the space
marked by their extremities, and the extremities of the axis, filled,
we would have the outline of a centrifugal animal.

Before discussing the influences which have increased and lo-
cated growth-force, it will be necessary to point out the mode in
which these influences must necessarily have effected growth.
Acceleration is only possible during the period of growth in ani-
mals, and during that time most of them are removed from the
influence of physical or biological causes, either through their
hidden lives or incapacity for the energetic performance of life
functions. These influences must, then, have operated on the

194 GENERAL EVOLUTION,

parents, and become energetic in the growing foetus of the next
generation. However little we may understand this mysterious
process, it is nevertheless a fact. Says Murphy, '' There is no act
which may not become habitual, and there is no habit that may
not be inherited." Materialized, this maybe rendered — there is
no act which does not direct growth-force, and therefore there is
no determination of growth-force which may not become habitual ;
there is, then, no habitual determination of growth-force which
may not be inherited ; and, of course, in a growing foetus becomes
at once energetic in the production of new structure in the direc-
tion inherited, which is acceleration.

But if the forces converted into growth-force are derived from
without the animal organism, whence and what the agency by
which the acceleration or retardation of the latter is inherited
from the parent ? A few suggestions only on this head can be
made in the fourth section.

III. THE LAW OF USE AKD EFFORT.

Up to this point we have followed paths more or less distinctly
traced in the field of nature. The positions taken appear to me
either to have been demonstrated or to have a great balance of
probability in their favor. In the closing part of this paper I
shall indulge in more of hypothesis than heretofore.

Since repetitive addition only produces identical results in
archetypes, and each effort produces results more and more unlike
its predecessor as structure becomes specialized, it becomes im-
portant to examine into the influences which have originally
modified the repetitive efforts successively, producing structures
more or less different in detail in the second generation from
those of the parents, in acceleration, or the reverse, in retarda-
tion.

Going further back, the question arises, why a simple exhibi-
tion of repetition (e. g., cell-division) should be converted into a
complex or duplicated repetition (e. g., jointed ray). This, it has
already been stated, is one consequence of increased amount of
the growth-force.

We then seek explanation of the main question, as to what de-
termines the location of this additional or new growth-force.
(Div. A.)

Lastly, why the total amount of this force should change in a
given individual or part of an individual. (Div. B.)

THE METHOD OF CREATION OF ORGANIC FORMS. I95

A. On the Location of Groivth-Force.

What are the influences locating growth-force ? The only
efficient ones with which we are acquainted, are, first, physical
and chemical causes ; second, use ; and I would add a third, viz. :
effort. I leave the first, as not especiaUy prominent in the econo-
my of type-growth among animals, and confine myself to the two
following. The effects of use are well known. We can not use
a muscle without increasing its bulk ; we can not long use the
teeth in mastication without inducing a renewed deposit of den-
tine within the pulp-cavity to meet the encroachments of attri-
tion. The hands of the laborer are always larger than those of
men of other pursuits. Pathology furnishes us with a host of hy-
pertrophies, exostoses, etc., produced by excessive use, or neces-
sity for increased means of performing excessive work. The
tendency, then, induced by use in the parent, is to add segments
or cells to the organ used. Use thus determines the locality of
new repetitions of parts already existing, and determines an in-
crease of growth-force at the same time, by the increase of food
always accompanying increase of work done, in every animal.

But supposing there be no part or organ to use. Such must
have been the condition of every animal prior to the appearance
of an additional digit or limb or other useful element. It ap-
pears to me that the cause of the determination of grow^th -force
is not merely the irritation of the part or organ used by contact
with the objects of its use. This would seem to be the remote
cause of the deposit of dentine in the used tooth ; in the thicken-
ing epidermis of the hand of the laborer ; in the wandering of
the lymph-cells to the scarified cornea of the frog in Cohnheim's
experiment. You can not rub the sclerotica of the eye without
producing an expansion of the capillary arteries and correspond-
ing increase in the amount of nutritive fluid. But the case may
be different in the muscles and other organs (as the pigment cells
of reptiles and fishes) which are under the control of the volition
of the animal. Here, and in many other instances which might
be cited, it can not be asserted that the nutrition of use is not
under the direct control of the will through the mediation of
nerve force. Therefore I am disposed to believe that growth-
force may be, through the motive, force of the animal, as readily
determined to a locality where an executive organ does not exist,
as to the first searment or cell of such an organ already com-

196 GENERAL EVOLUTION.

menced, and that therefore effort is, in the order of time, the
first factor in acceleration.

Addition and subtraction of growth-force, in accordance with
the modes pointed out below, account for the existence of many
characters which are not adaptive in their nature.

Acceleration under the influence of effort accounts for the ex-
istence of rudiments of organs in process of develoj)ment, while
rudiments of organs in process of extinction are results of retarda-
tion, occasioned by absolute or complementary loss of growth-force.
Many other characters will follow, at a distance, the modification
resulting from the operation of these laws.

Examples of the Influence of Physical Causes. — This is nowhere
better seen than in the case of coloration, which requires the light
of the sun for its production. The most striking examples of this
are seen in the colorless surface of animals inhabiting the recesses
of cayes, as the blind craw-fish and the AmUyopsis, etc. If evolu-
tion be true, these have descended from more highly colored jDro-
genitors. The flat fishes, also {Pleuronectidce), as is known, swim
on one side in adult age, but many of them are hatched symmetrical
fishes, or nearly so, one eye rotating from one side to the other by
a twisting of the cranial bones. It is thus probable that they have
descended from symmetrical fishes, which were similarly colored
on both sides. Now the lower side is colorless, the upj^er retain-
ing often brilliant hues. The influence of sunlight is thus as dis-
tinctly discoverable among animals as among plants, where it has
been generally accepted as a principle of vegetable physiology.*

Examples of the Effects of Effort and Use. — a. The Respiratory
and Circulatory System of Vei^tehrates. — It is well known that the
succession of classes of Vertebrates is measured first by their adapta-
tion to aeration in water, and then by their successive departures
from this type in connection with the faculty of breathing air.
The same succession of structure is traversed by the embryos of
the vertebrates, the number of stages passed being measured by
the final status of the adult. This transition takes place in the
Batrachia later in development than in any other class. Now, it
is well known that the transition or metamorphosis may be delayed

* In this and similar cases, care must be taken not to misunderstand the writer
by supposing him to mean that in each generation separately the peculiar coloration
is the result of changed exposure to light. The evolutionist will understand that the
effect of such influence increases with succeeding generations by the addition to in-
herited character of the effect of immediate external cause.

THE METHOD OF CREATION OF ORGANIC FORMS. 197

or encouraged by suppression of use of the branchial and encourage-
ment of use of the pulmonary organs, or the reverse.

The aquatic respiration of tadpoles may be indefinitely pro-
longed by preventing their access to the surface, and it is known
that in nature the size or age of the larva at time of metamorphosis
may vary much in the same species. If perennibranchiates (Siren,
e. g.) are deprived of their branchiae, they will aerate blood by
the lungs exclusively, and there is no reason to doubt that by use
of these, and disuse of the branchiae, aerial respiration might be-
come the habit of the animal. It is also easy to perceive that geo-
logic changes would bring about a necessity for precisely this change
of habit. This occurred in the period of the coal measures, where
large fresh-water areas were desiccated, and it was precisely at this
period that many air-breathing Batrachians originated and had a
great development.

j3. The rattle of the Rattlesnake. — Nearly all the larger harm-
less snakes which live on the ground have a habit of throwing the
end of the tail into violent vibrations when alarmed or excited,
with the view of alarming a supposed enemy. Among Coronelline
snakes, Ophiholus triangulus possesses it ; among the water snakes,
Tropidonotus sipedon. In the typical Colubrine group the black
snake, Bascanium constrictor, is an example ; Pityophis sayi also
shakes the tail violently. The copperhead {Ancistrodon contor-
trix) and the moccasin {A. piscivorus) (fide Giinther) have the
habit in a marked degree. Among the rattlesnakes it is a means
of both warning and defense, in connection with the rattle which
they carry.

In the structure of the end of the tail of harmless snakes, we
see a trace of the first button of the rattle in a horny cap that covers
the terminal vertebrae. In the venomous genera, it is conspicuous
in Lachesis especially, reaching a considerable length and having
a lateral groove. In the plate-headed rattlesnakes (Crotalus) this
corneous cap is inflated into a button with lateral groove, and in
some of them possesses only one or two buttons or joints. In the
perfected rattlesnakes {Gaudisona) not only are the segments nu-
merous and inflated, but a number of the terminal caudal vertebra?
are greatly enlarged vertically, and co-ossified into a mass.* This
is important from the fact that the rattlesnakes are the most spe-

* See good figures of this structure in *' Zeitschr. f. wissensch. Zoologic," viii,
Tab. 12.

198 GENERAL EVOLUTION.

cialized of all snakes, standing at the head of the order, and as
such, on the principle of acceleratio7i, present the greatest amount
of grade-nutrition.

Now it appears to me that the constant habit of violent vibra-
tion in a part tends to determine an increased amount of nutritive
fluid to it, in other words to localize growth-nutrition, and when
this has attained complex repetition or grade-nutrition, to result
in new grade-structure. (The segments of the rattle being nearly
all alike, it is a case of simple repetition.) This view appears to
be as reasonable as that generally entertained with regard to the
cause of spavin in the horse's leg. Here, owing to excessive use,
exostoses appear on the bones surrounding the tibio-tarsal articula-
tion. As to the reason of tbe structure in question not appearing
in forms lower in the scale than the rattlesnake, it is explained
below, if the law of accumulation of grade-nutrition be true. (See
Sec. B.) This is, that repetition (or acceleration) is only possible
where the animal has an excess of growth-force at its disposal, or
can abstract it from some portion which is unused or useless.

y. On horns. — The possession of horns on the posterior part
of the cranium, as defenses against enemies, is a character found
in many distinct types of animals. (Herbivora have no (dental)
weapons and need horns.) It is seen in the Batracliia Stego-
cephala in the extinct genus Ceraterpeton ; among ^?^^^r« it is
approached by Triprion and Hemiplir actus. Among Reptilia it
is well marked in PTirynosoma, a Lacertilian genus. In Mamma-
lia the Artiodactyla Ruminantia are the horned animals of the
order. We have opportunities of observing the habits of these
representatives of the Frogs, the Lizards, and the Mammals.

In the first case, any one who has kept ordinary toads and
tree-toads in confinement, is aware that when attacked and unable
to escape, they defend themselves by presenting the top of the
head forward and using it as a shield. Now I have already
pointed out * that in both toads, tree-toads, and frogs there are
natural series of genera, measured by the degree of ossification of
the superior cranial walls, the longest being that of the Hylidse,
which embraces six terms, viz. : Hylella, Hyla, Scytopis, Osteo-
ceplialus, Trachycephalus, and Triprion. The two last have the
head thoroughly shielded, and Hemipliractus has projecting an-
gles which appear in some South American forms, described bv M.

* " Origin of Geaera," 1868, p. 14. This work, article L

THE METHOD OF CREATION OF ORGANIC FORMS. 199

Espada, to be developed into short horns. That this excessive
ossification is associated with the habit of protecting the whole
body with the front seems likely.

In the case of Phrynosoma we know that precisely the same
habit is associated with the presence of the sharp horns ; and that
some genera without horns possess it also. Phrynosoma is an ex-
ceptionally sluggish genus in a family of most active forms, and
must necessarily resort to this mode of defense more than they.

In the case of Ruminants, we also know that defense is accom-
plished by throwing the head down with the horns thrown for-
ward. But this is not confined to this group. That generalized
suborder, the Artiodactyla Omnivora, represented by the hog,
which were no doubt the genetic predecessors of the Euminants
in time, also throw the head down in defense in the same way,
having thus a manner totally distinct from that seen in the Car-
nivora. The latter show their teeth and often crouch prepara-
tory to a leap.

These cases present so constant an association between habit
and use that, admitting evolution, we are compelled to believe
that the structure has given rise to the habit or the habit to the
structure. In the former case we have to suppose, with the au-
thor of ^' Katural Selection," that among the many spontaneous
variations rudimental horns occasionally appeared, and that their
possessors, being thus favored in the struggle for existence, were
preserved and multiplied ; while those not favored dwindled, and
were ultimately nearly all extirpated or starved. The question
of origin is here left to chance, and Alfred Bennett has made a
mathematical estimate of the chances of any particular profitable
variation occurring among the great number of possibilities of the
case. This has shown the chance to be so excessively small as to
amount in most cases to a great improbability.

If we turn to the probabilities of such structure having arisen
through the selection of that mode of defense by the animal, we
find them greatly increased. The position occupied by the horns,
in all the animals described, is that which is at once brought into
contact with an enemy in conflict, and as sport among animals is
a gentle imitation of conflict, the part would be constantly excited
in sport as well. With an excess of growth-nutrition, our knowl-
edge of the effects of friction on the epidermis, and of excessive
ligamentous strain and inflammation on bone (e. g., spavin in
horses), as well as of abnormal exostoses in general, would warrant

200 GENERAL EYOLUTION.

US in the belief that the use of the angles of the parts in question
in these animals would result in a normal exostosis, of a simple
kind in the frogs, or as horn cores in the Euminantia.* As to the
sheathing of the cores in the Bovidce, and nakedness in the Cer-
vidcB, it is in curious relation to their habitat and to their habits.
The epidermis and derm would of course share in the effects of
friction. In the Bovidae which dwell in treeless plains, or feed
on the grasses in great i:)art, the development of these coverings of
the horn cores into a horny sheath would naturally meet with
no interruption. In the case of the deer, which mostly live in
forests or browse on trees, constant contact with the latter would
prevent the healthy growth of the dermal covering, and it would
be liable to injury or constant excoriation by the animals them-
selves on the branches of trees, etc. This we know to be the pres-
ent habit of the deer as regards the dermal covering of the horns. f
I have elsewhere pointed out the similar connection between the
dental structure and habitat among the oxen and the deer. The
former, eating the harder grasses, are provided against the conse-
quent rapid attrition of the tooth by a prismatic form, which
allows of more prolonged growth and more rapid protrusion.
The deer, in accordance with their foliage-eating habits, do not
wear the crown of the tooth with such rapidity. Long-continned
protrusion is not so necessary, hence the teeth are more distinctly
rooted and have a prominence or shoulder, distinguishing the
body of the crown.

B. Change in Amount of Groioth- Force.

1. Absolute increase of Groiutli- Force. — As every type has had
its period of greatest development in numbers, size, and complica-
tion of structure, the present law indicates as an exjolanation, a
culmination of the process of conversion of growth-force from its
energetic to its potential state in tissue. The cause is primarily
the increased exercise of effort and use, which, while effecting a
conversion, increases the capacity of the organs by which further
conversion is effected.

* The now well-known fact that all cranial ossification was primitively dermal,
is confirmatory of the idea that its appearance was due to moderate friction of the
skin on resistant bodies. (Ed, 1886.)

f Palaeontological studies go far to show that the origin of the shedding of the
deer's horn was due to the loss of their dermal covering, and that this was caused by
violent use. (1886.)

THE METHOD OF CREATION OF ORGANIC FORMS. 201

2. Local increase of Growth-Force.— Bxam-phs of a local in-
crease of this kind are probably to be seen in conyoluted organs ;
as the convolutions of the brain in higher Mammalia ; the convo-
lutions of the tooth-dentine of the Labyrinthodont Batrachia ; the
same phenomenon in the cotyledons or plumule of some seeds. In
these cases the superficial area of the parts is excessively developed,
and the inclosing organs not being proportionately enlarged, a
convolution necessary follows. In the first case, the skull ; in the
second, the alveolus ; in the third case, the seed-envelope, restrain
the expanse of the contained part, which would otherwise follow
increase of growth-force.

3. Absolute loss of Growth-Force.— This will follow defective
nutrition, produced by inability of the animal to obtain heat and
food requisite to that end. This is supposed to be due, according
to the view hereafter proposed, primarily to deficiency of intelli-
gence, in failing to adapt habits to changed physical circumstances,
and secondarily to the unfavorable influence of such changed cir-
cumstances. The extinction of highly specialized types, which
has closed so many lines of animal types, will be accounted for by
their less degree of plasticity and want of capacity for change un-
der such changed circumstances. Such changes consist of modified
topography and temperature, with irruptions of many new forms
of life by migration. The less developed forms would be most
likely to experience modification of structure under a new order
of things, and paleontology teaches that the predecessors of the
characteristic types of one period were of the less specialized forms
of that period which went before.

Thus is explained the fact that, in following out the line of
succession of animal forms, we have constantly to retrace our steps
from specialized extremes (as osseous fishes, tailless Batrachia,
song birds, etc.) to more generalized or simple forms, in order to
advance beyond.

4. The complementary dimimitioii of growth-nutrition follows
the excess of the same in a new locality or organ, of necessity, if
the whole amount of which an animal is capable be, as I believe,
fixed. In this way are explained the cases of retardation of char-
acter seen in most higher types. The discovery of truly comple-
mentary parts is a matter of nice observation and experiment.
Perhaps the following cases may be correctly explained.

A complementary loss of growth-force may be seen in absence
of superior incisor teeth and digits in ruminating Mammalia, where

202 GENERAL EVOLUTION".

excessive force is evidently expended in the development of horns,
and complication of stomach and digestive organs. The excess
devoted to the latter region may account for the lack of teeth at
its anterior orifice, the mouth ; otherwise, there appears to be no
reason why the ruminating animals should not have the superior
incisors as well developed as in the odd-toed (Perissodactyl) Un-
gulates, many of which graze and browse. The loss to the osseous
system in the subtraction of digits may be made up in the develop-
ment of horns and horn-cores, the horn sheath being perhaps the
complement of the lost hoofs. It is not proposed to assert that
similar parts or organs are necessarily and in all groups comple-
mentary to each other. The horse has the bones of the feet still
further reduced than the ox, and is nevertheless without horns.
The expenditure of the complementary growth-force may be sought
elsewhere in this animal. The lateral digits of the Equidce are
successively retarded in their growth, their reduction being marked
in Hiypotlierium, the last of the three-toed horses ; it is accom-
panied by an almost coincident acceleration in the growth-nutri-
tion of the middle toe, which thus ajipears to be complementary
to them.

The superior incisors of the Artiodadyla disa^Dpear coincident-
ally with the appearance of horns, which always exist in the tooth-
less division of the order, excej)t in some very small antelopes
(Cephalophus, etc.) where the whole amount of growth-force is
small. Possibly the superior incisors and horns are complementary
here. The retardation in development of the teeth in the higher
apes and men, as compared with the lower apes, is coincident with
the increase of number of brain convolutions. That this is not
necessarily coincident with reduction of teeth in other groups is
plainly proved by the rodents and CMromys, where the loss of many
teeth is complementary to the great size of the incisors of the mid-
dle pair. But in man there is no complementary increase of
other teeth, and the reduction is no doubt due to contraction of
the jaws, which is complementary to increase in other parts of the
cranium, in both apes and men.

I am confident that the origin and loss of many structures may
be accounted for in this way, and the correlation of parts to each
other be measured accurately.

Objection, — The first one which arises is that which the author
of the ^^ Vestiges of Creation " made against Lamarck's theory of a
similar kind, i. e., that by assuming that effort, use, and physical

THE METHOD OF OREATIO]^ OF ORGANIC FORMS. 203

causes have originated modifications of structure, we give the
adaptive principle too much to do. I have made the same objec-
tion to the theory of natural selection. It is true that an ai^plica-
tion to a purpose is involved in the present theory of the 'location
of growth-force " ; but in point of fact, a large number of non-
adaptive characters are accounted for by it. These are the rudi-
mental and transitional ones which mark the successive steps pre-
liminary to the completion of an adaptive structure ; second, those
produced by deficiency of growth-force in less favored regions of
the body ; and third and fourth, phenomena consequent on general
deficiency and excess of growth-force.

And it may be said in conclusion that if the three principles,
or if use especially, should be found to be inadequate to the service
here demanded of them, it may be at least said that they, or the
last named, constitute the only controllers of growth-force to any
degree at all with which we are acquainted.

lY. 01^ GKADE-IKFLUE5^CE.

The object of the present section is the attempt to discuss how
the influence of effort and use on the parent is placed in a position
to be inherited by the offspring.

A. Of the Nature of Grade-Lifluence.

In the first place, it is necessary to note the definition and char-
acter of grade-influence.

a. Growth- force uninfluenced by grade-influence simply adds
tissue either {a) in enlarging size, or {b) in rejilacing waste. It
does this by repeating the cell, by division, in localities which have
already assumed their specific form. This form of growth-force
may persist throughout life, but with diminished energy in age.

(i. Grade-influence directs growth-force in building up the tis-
sues into organs, and constructs the parts of the body successively
to completion, the result expressing the type or grade of the ani-
mal or plant. Its energy terminates with maturity, except in
cases of periodical reproduction of sexual ornaments of the male
(birds, deer), where it continues throughout life, appearing at
regular intervals.

But it has occurred in acceleration that instead of a simple repe-
tition of the ultimate histological element of an organism, in add-
ing to its amount, it adds a completely organized part of the struct-

204 GENERAL EVOLUTION.

ure, as a tube, a phalange, a digit, a limb or an arch ; an ocellus
or a tooth. For instance, in the genus Amhlystoma, one section
possesses four phalanges on the longest digit ; another section
exhibits but three. In the species A, mavortium, some individuals
have the small number of phalanges, but the majority possess the
larger number. As all are of common parentage, a whole phalange
has been lost or added. The explanation of this phenomenon is
essential to the comprehension of the origin of type structures.

* In plants, growth-nutrition continues throughout life, but in
the higher plants it is more active during the earlier years in peren-
nial species, addition to size becoming less and less marked with
increasing age. Grade-nutrition also persists throughout life, but
is chiefly active during a short period only of every year, or during
flowering and fruiting. Not only in the production of the repro-
ductive organs, but also in the yearly additions to other tyj^ical
parts of the plant, grade-nutrition is active.

** In animals, growth-nutrition is more active in the early
stages of life, but is continued throughout in the lower divisions ;
in the highest, it is also continued throughout life, but there is a
greater contrast between its results during youth, when nearly the
whole size is attained, and during age, where the additions are
much less.

Grade-nutrition is, on the other hand, entirely confined to in-
fancy and youth, except in those low animals which produce their
reproductive organs periodically (some Fntozoa, etc.), where it may
be said to be in nearly the same condition as in plants.

y. While the amount of simple growth-force, represented in
adult living animals, has varied very irregularly throughout the
animal kingdom, there being large and small in every division, it
would seem to have accumulated, on the whole, with the rising
scale of animal types. Thus the lower or Protozoa are the small-
est ; Radiates are next in size ; Molluscs and Articulates reach
nearly the same maximum, which exceeds that of the Radiates,
and falls far below that of the Vertebrates. Among the last the
Mammalia have attained as large if not larger size than any of the
other orders (e. g., Cetaced). This is, however, not necessary to
the history of evolution.

That an increased amount of grade growth-force has been con-
stantly rendered potential during the advance of time is clear, if
the preceding inferences be true. It is also evident that some in-
dividuals have accumulated it more rapidly than others. If all

THE METHOD OF CREATION OF ORGANIC FORMS.

205

alike originated from the simplest forms known to us. Multi-
tudes have remained in the earliest stages {Protozoa) of the whole
series, or of their own special series {Lingula), forming *' persist-
ent types " ; or taken directions which rendered them incapable
of expansion beyond a certain point without exhaustion or death ;
for example, complicated types, as Ammonitidcs. The quadruma-
nous animal, which was the progenitor of man, may thus be be-
lieved to have acquired a higher capacity of this accumulation
than his contemporaries.

Assuming the nucleated cell to be the ultimate element of or-
ganic tissue, there are two types of hfe in which grade-influence
has not appeared, viz. : unicellular animals and plants, and living
forms composed of homogeneous protoplasm. In the latter neither
grade-influence nor animal growth-force is potential ; in the for-
mer, simple growth-force only. It is therefore apparent that grade-
influence has been developed in the organism itself ; perhaps this
may have been in the plant, through the modified influence of ex-
ternal physical causes ; in the animal, if our inductions as to use
and effort be true, under the influence of the activities of the par-
ent, which determined a structural change either in itself or in
its offspring. The possibilities of this origin are considered in the
next section.

8. The Location of Growth-Force proceeds under the direction
of what Prof. Henry calls "Vital Influence." With this author I
discard the use of the term "Vital Force," what was originally
understood by that term being a complex of distinct ideas. The
Vital forces are (nerve-force) Neurism, (growth-force) Bathnism,
and (thought-force) Plirenism.'^ All these are supposed to be
correlated to the Physical Forces, but are under direction and
control of the Vital principle which locates their action, etc., just
as molecular or atomic constitution determines the locality and
character of the physical forces. The laws of the vital principle
and of atomic constitution also determine the nature of the con-
version of one force into another. Now, since physical and vital
forces are correlated and convertible, the close relationship of the
two controlling principles becomes obvious and suggestive of their
identity.

* The objection of President Barnard to thought being an exhibition of a force,
is that " thought can not be measured." This objection docs not take into consid-
eration the two-fold nature of thought. The amount of thought can most assuredly
be measured, the quality of the thought can not.

206 GENERAL EVOLUTION.

Dr. Carpenter, in describing the correlation of j)hysical and
vital forces, defines the difference of organic species to be similar
to that prevailing between different chemical bodies (the latter
depending on different molecular and atomic constitution), which
leads them " to 'behave differently" from each other under simi-
lar circumstances. This may be more fully expressed by saying
that different species possess different capacities for the location
of the conversion of the physical forces into growth-force. A
" descent with modifications " contemplated by a process of evolu-
tion, signifies a progressive change in this capacity. Acceleration
means an increase in this capacity ; retardation a diminution of
it. Grade-infiuence means the influence which produces this
change of capacity.

B, The Origin of Grade-Injiuence.

Living protoplasm can convert heat and nutriment into
growth-force without the agency of the nervous system. This
is proved by the nutrition of the Protozoa and Ccelenterata, and
from experiments on the muscles of frogs, etc. In the latter case,
as is well known, the nerve may be divided, and the muscle retain
its size if a current of electricity be passed through it, thus sus-
taining the nutrition. As the presence and structure of the nerv-
ous system is in relation to the specialization of animal struct-
ure in other respects, it is very probable that the nervous system is
in higher animals the agent of the location of growth -force. In
the lowest it is not affected by any such means. As the nervous
system is the instrument of the metaj^hysical peculiarities of the
animal (emotions, choice, etc.), we may conclude that, in the
lower animals, location of growth-force is influenced by necessity
without choice ; in the higher by necessity with choice.

The impulses derived from the nervous system, it is known,
may be reflex or automatic in answer to stimuli from without.
They may become so, also, after having been originated conscious-
ly or by effort of will. In the case of habits, frequent exercise of
choice has so impressed the nervous system as to result in its
repetition of effort, often in opposition to changed choice.

The influence of effort in muscular action, through the nervous
system, appears to be, first, to enable it to convert heat to nerve-
force, and, then, to conduct nerve-force to the involuntary mus-
cles, or those controlling circulation, where it is converted into
motion, which thus controls nutrition throuirh circulation. The

THE METHOD OF CREATION OF ORGANIC FORMS. 207

nervous system, like others, develops in capacity with use, hence
probably nerve-tissue converts heat * into nerve-force as muscular
tissue converts heat into motion. In other words, by repetition,
the capacity of the nervous system for this conversion of heat is
known to increase. As the amount of heat converted is in pro-
portion to the amount of appropriate nerve-tissue (see above), it is
evident that use and effort increase the amount of nerve-tissue.

The phenomena of thought render the same modification of
structure j)robable. Effort in the direction of thought is supposed
to convert heat into thought-force. Inasmuch as the more intelli-
gent animals possess the highest development of cerebral hemi-
spheres, it is highly probable that brain substance converts heat
into growth-force also, which produces tissue of its own kind pre-
cisely as muscle does.

As different parts of the nervous centers subserve different
purposes, the development of these parts must proceed approxi-
mately under the influence of special kinds of effort and use.
Where, as. in the adult, heat is converted into growth-force in the
tissues to a very limited extent, if the above principles be true,
the conversion of heat by the nervous system into nerve growth-
force and tissue is, on the other hand, not terminated.

Capacity for effecting conversion of force is regarded, as above
pointed out, as dependent on molecular constitution. Hence we
conclude that change in that capacity on the part of the nervous
system involves a molecular change in its constitution.

Now, we know physical and metaphysical peculiarities of
parents to be inherited by offspring ; hence, no doubt, the nervous
structure determinative of growth-force is inherited. This will
then control the localities of special conversion of heat, etc.
(from the mother), into growth-force, in accordance with the
structure of the parent, and the more decidedly, as its own in-
crease progresses.

The result will be acceleration, or construction of tissues and
organs in excess of those of the parent, if the effort or use de-
voted to a nerve or organ be represented in the nerve-center of
the parent by a greater amount of force-converting tissue than is

* The supposition that this and other forms of vital energy are derived from
metamorphosis of heat, was in accordance with views held at the time this essay
was written (1871). The much more probable hypothesis is that such energy is
derived from retrograde metamorphosis of nutritive material. (Ed. 1886.)

208 GENERAL EVOLUTIOI^.

necessary when inherited in the foetus for the construction (by
conversion) of tissues and organs like those of the parent.

,y^ That this is a partial explanation of inheritance, is rendered
probable from the fact that the types of structure presented by

\ the nervous centers express the grade of the animals possessing
them far more nearly than those of any other organ or set of or-
gans. If the brain, like other organs, develops by intelligent use,
it can not be doubted that this relation of its development to

I grade is not accidental, but that grade-structure * is an expression
of its capacities, physical and mental.

V. o:n" intelligent selection.

As neither nse nor effort can be ascribed to plants, and as we
know that their life history is much more dependent on their sur-
roundings than is that of animals, we naturally look to the physi-
cal and chemical causes as having a prime influence in the origina-
tion of their type-structures. Without greater familiarity with
the subject, I will not attempt to say how far the various degrees
of growth-force possessed by parent plants, located under the influ-
ence of meteoric and other surroundings, and preserved, destroyed
or restricted by natural selection, may account for the characters
of their successors of the present period. But other agencies simi-
lar to use, that is, automatic movements, may be also introduced
as an element in the argument. The movements of tendrils seek-
ing for support may be here considered, and, as Dr. Asa Gray has
pointed out, have consequences similar to those of use in animals.
When the tendril seizes a support, growth-force is located at the
point of contact, for the tendril increases considerably in thick-
ness.

Among animals of the lowest grade, movement must be quite
similar to those of plants, or automatic from the start, and not
even at the beginning under the influence of will. Evidence of
will is, however, soon seen in the determinate movements of many
of the Protozoa in the seizing of food. With will necessarily ap-
pears a power of choice, however limited in its lowest exhibitions,
by the lack of suggestive metaphysical qualities, or the fewness of
alternatives of action presented by surrounding circumstances, to
animals of low and simple organism. We can, however, believe

^ Grade growth-force is not regarded here or elsewhere as a simple form of
energy, but as a class of energies, which are the resultants of the interference of
mind (i, e., consciousness) with simple growth-force. (Ed. 1886.)

THE METHOD OF CREATION OF ORGANIC FORMS. 209

that the presence of greater or less number of external facilities
for action characterize different situations on the earth's surface,
as well as that greater and less metaphysical capacity for perceiv-
ing and taking advantage of them must exist in diiferent indi-
viduals of every species of animal, however low, which possesses
consciousness and will. These qualities must, of course, influence
eifort and use to the advantage of the animal, or the reverse.

Effort and use have very various immediate stimuli to their
exertion.

Use of a part by an animal is either compulsory or optional.
In either case, the use may be followed by an increase of nutrition
under the influence of reflex action or of direct volition.

A compulsory use would naturally occur in new situations
which take place apart from the control of the animal, where no
alternatives are presented. Such a case would arise in a submerg-
ence of land where land-animals might be imprisoned on an island
or in swamps surrounded by water, and compelled to assume a
more or less aquatic life. Another case, which has also probably
often occurred, would be when the enemies of a species should so
increase as to compel a large number of the latter to combat who
had previously escaped it.

In these cases, the structure produced would be necessarily
adaptive. But the effect would sometimes be to destroy or injure
the animals (retard them) thus brought into new situations and
compelled to an additional struggle for existence, as has, no
doubt, been the case in geologic history.

Direct compulsion would also exist where alternatives should
be presented by nature, but of which the animal would not be
sufficiently intelligent to take advantage.

Most situations in the struggle for existence afford alterna-
tives, and the most intelligent individuals of a species will take
advantage of those most beneficial. Nevertheless, it is scarcely
conceivable that any change or increase of effort, or use, could
take place apart from compulsion derived from the relation of
external circumstances, as a more or less remote cause.

Preservation, with modifications, would most probably ensue
when change of stimulus should occur gradually, though change
of structure might occur abruptly, under the law of expression
points. *

* See " Origin of Genera," p. 3S.
14

210

GENERAL EYOLUTIOX.

Choice is influence not only by intelligence, but by the imagi-
nation and by the emotions.

Intelligence is a conservative principle, and always will direct
effort and use into lines which will be beneficial to its possessor.
Here we have the source of the fittest — i. e., addition of parts by
increase and location of growth-force, directed by the will — the
will being under the influence of various kinds of compulsion in
the lower, and intelligent option among higher animals.

The influences locating growth -force may be tabulated as
follows :

DIVISION.

INFLUENCE.

Plants.

Physical and )
chemical. ^

9 9

Plants with me-
c h a n i c a 1 move-
ments; animals
with indeterminate
movements.

Animals with de- ^
terminate move- I
ments or will,* but j
no intelligence. J

Animals with
will and less intel-
ligence.

Animals with
more intelligence.

-h use

-f- effort under
compulsion.

((

(( ((

-f choice.

-I- intelligent choice.

As examples of intelligent selection, the modified organisms of
the varieties of bees and ants must be regarded as striking cases.
Had all in the hive or hill been modified alike, all soldiers, neu-
ters, etc., the origin of the structures might have been thought to
be compulsory ; but varied and adapted as the different forms are
to the wants of a community, the influence of intelligence is too
obvious to be denied.

The selection of food offers an opportunity for the exercise of

* Will must be here regarded as the answer to stimulus, without any element of
freedom. See Article XX, on the " Origin of the Will." (Ed. 1886.)

THE METHOD OF CREATION OF ORGANIC FORMS. 211

intelligence, and the adoption of means for obtaining it still
greater ones. It is here that intelligent selection proves its su-
premacy as a guide of use, and consequently of structure, to all
the other agencies here proposed. The preference for vegetable
or for animal food determined by the choice of individual animals
among the omnivores, which were, no doubt, according to the
paleontological record, the predecessors of our herbivores, and per-
haps of carnivores also, must have determined their course of life
and thus all their parts, into these totally distinct directions.
The choice of food under ground, on the ground, or in the trees
would necessarily direct the uses of organs in the appropriate
directions respectively.

In the selection of means of defense a minor range of choice is
presented. The choice must be limited to the highest capabilities
of the animal, since in defense, these will, as a general thing, be
put forth. This will, however, not be necessarily the case, but
will depend in some measure on the intelligence of the animal, as
we readily observe in the case of domesticated species.

In the case of the rattlesnake, already cited, the habit of rapid
vibration of the tail appears to me to be the result of choice, and
not of compulsion. For the cobra of India, for the same pur-
pose, expands the anterior ribs, forming a hood, which is a very
different habit.* Here are two alternatives, from which choice
might be made, and violent hissing is a third, which the species
of the colubrine genus Pityopliis have adopted to some purpose.
As to the benefit of the rattle, it no doubt protects the animal
from all foes other than man ; but is rather a disadvantage as re-
gards the latter, being by a beautiful turn of events a protection
to the higher animal.

On the principle of natural selection it might be supposed that
the harmless snakes which imitate the Crotalus for the sake of
defense were preserved ; but if the above explanation of the origin
of the habit in the latter be true, the second explanation is not
valid. (Since in time the harmless snakes preceded the rattle-
snakes. Ed. 1886.)

The power of metachrosis, or of changing the color at will, by
the expansion under nerve-influence of special pigment cells, exists
in most Reptilia, Batrachia, and fishes. It is then easy to believe
that free choice should, under certain circumstances, so habitually

* The North American Heterodons possess a similar habit. (Ed. 1S86.)

212 GENERAL EVOLUTION.

avoid one or another color as to result finally in a loss of the power
to produce it.

Thus, it appears to be a fact that not only are species of fishes
which dwell in the mud of darker hues than those that inhabit
clear water, but that individuals of the same species differ in a simi-
lar manner in relation to their habitats ; those that live in impure
or muddy waters having darker tints than those of clear streams.

Land animals present equally abundant and remarkable imita-
tions of the objects or substances on which they live. This is
well known in insects and spiders, which look like sticks or
leaves, or the flowers on which they feed. It is seen in reptiles,
which in very many cases can voluntarily assume the hue of leaf,
stone, or bark, or have constantly the gray color of their native
desert sands.

These cases are largely selective or optional in their origin, for
though metachrosis is also induced by some external stimulus, as
an enemy or a food animal, yet other means of escaj)ing the one
and procuring the other are generally open.

These facts pave the way for a consideration of the phenome-
non of mimetic analogy, which, though well known to naturalists,
may be illustrated by the following new facts :

On the plains of Kansas there is a species of Mutilla whose
abdomen and thorax are colored ochraceous, or brown-yellow,
above. A spider of the genus SaUicus is equally abundant, and
is almost j)recisely similar in the color of the upper surfaces, so
much so as to deceive any but a most careful observer. The
Mutilla being a well-armed insect, and a severe stinger, there can
be no doubt that the SaUicus derives considerable immunity from
enemies from its resemblance.

On the same plains, the Crotalus conjiuentus, or prairie rattle-
snake, abounds. It is an olive gray, with a series of transverse
brown dorsal spots, and two rows of smaller lateral ones. The
head exhibits a number of brown and white bands. The prairie
Heteroclon {H. nasicus) possesses not only the same tints but the
same pattern of coloration, and at a short distance can not be dis-
tinguished from it.

In consequence, as one may justly say, this species is, with the
rattlesnake, the most common serpent of the plains, as it shares,
no doubt, in the protection which the armature of the Caudisona
gives its possessor. This is in accordance with the views of Wal-
lace and Bates.

THE METHOD OF CREATION OF ORGANIC FORMS. 213

A curious case occurred to me in four species of fishes, which
I took in a small tributary of the Yadkin River, in Roane County,
N. 0, Among several others, there were varieties of the widely
distributed species Chaenohryttus viridis, Hypsilepis analostanus,
and Ptychostomus pidie7isis (each representing a different family),
which differ from the typical form of each in the same manner,
viz. : in having the back and upper part of the sides with longi-
tudinal black lines, produced by a line along the middle of each
scale. This peculiarity I have not observed in these species from
any other locality. Until I had examined them I thought them
new species.

The only other species presenting such marking in the Yadkin
River is the large perch, the Roccus lineatus. According to the
theory of natural selection a resemblance to this well-armed species
might be of advantage to the much weaker species in question ;
yet the same species co-exist in other rivers without presenting
the same mimicry.

It is difficult not to urge the importance of the causes already
regarded as efficient in the origination of structure in the present
branch of the subject also. We are especially disposed to call in
use and effort here, after noticing how much more distinctly
change of color is under the control of the animal, than change of
shape. It must, however, be borne in mind that similar resem-
blances exist among plants ; though, as Professor Dyer shows, a
large majority of these cases occur in species of different floral
regions. Thus in this case, as in those of structure already cited,
we appeal first to physical laws in the lowest beings, but with the
increasing interference of use, effort, and intelligence, as we rise in
the scale. Thus it is that, in the Vertebrates generally, the mi-
metic resemblances are found in species of the same region, where
only an intelligent or emotional agency could be illustrated. If
among animals as low as butterflies the influence of intelligence be
denied, that of admiration for the beauty, or fear of the armature,
of the predominant species imitated, would appear to be sufficient
to account for the result. Admiration and fear are possessed by
animals of very low organization, and, with the instincts of hunger
and reproduction, constitute the most intense metaphysical con-
ditions of which they are capable. But our knowledge of this
branch of the subject is less than it ought to be, for animals pos-
sess many mental attributes for which they get little credit.

It appears to be impossible to account for the highest il lustra-

214 GENERAL EVOLUTION.

tions of mimetic analogy in any other way, the supposition of
Wallace that such forms must be spontaneously produced, and
then preserved by natural selection, being no explanation. It has
been shown by Bennett that the chances of such modification aris-
ing out of the many possibilities are exceedingly small.

If the above positions be true, we have here also the theory of
the development of intelligence and of other metaphysical traits.
In accordance with it, each trait appropriates from the material
world the means of perpetuating its exhibitions by constructing its
instruments. These react by furnishing increased means of exer-
cise of these qualities, which have thus grown to their full expres-
sion in man.

VI.

A EEVIEW OF THE MODEEN DOCTRmE OF EVO-
LUTION.*

The doctrine of evolution of organic types is sometimes appro-
priately called the doctrine of derivation, and its supporters, deriv-
atists. This is because it teaches the derivation of species, genera,
and other divisions, from pre-existent ones, by a process of modi-
fication in ordinary descent by reproduction. The opposite or
creativist doctrine teaches that these forms were created as we see
them to-day, or nearly so ; and that the natural divisions and spe-
cies of organic beings have never been capable of change, the one
into the other.

I. THE EVIDENCE FOR EVOLUTIOIS^

The reasons w^hich induce me to accept the derivatist doctrine,
and to reject the creational, fall under the two heads of probabil-
ities and conclusive evidence. The probabilities are cumulative in
their pointings, and strengthen that part of the evidence which
is, to my mind, conclusive. The reasons why derivation is prob-
able are the successional relation of increment or decrement of
structure, observed in :

1. Systematic relation (taxonomy) ; 2. Embryonic growth
(embryology) ; 3. In geologic time (paleontology) ; 4. And in the
coincidence in the successions seen in Nos. 1, 2, and 3.

The fact that it is necessary to arrange animals in an order cor-
responding with the phases of their embryonic history is remark-
able ; but the further fact, shown by paleontology, that the same
succession marked the ages of past time, at once brings evolution
within the limits of strong probability. Nevertheless, all this
might have been a mere system, without transitions between its

* Abstract of a lecture delivered before the California Academy of Sciences, Oct.
27, 1879.

216 GENERAL EVOLUTION.

members ; organic types miglit have been created unchangeable,
but presenting the mutual relations in question. But if transi-
tions among these members can be shown to take i^lace, then
indeed the phenomena mentioned received a sufficient explanation.
They are seen to be the necessary relations of the parts of a shift-
ing scene of progression and retrogression ; they express combina-
tions of structure, which, though often long enduring, are, never-
theless, not perpetual, but give way to other combinations to be
in their turn dissolved. Now, if there is anything well known in
nature, it is that there are divisions of various ranks in the vege-
table and animal kingdoms, whose contents present variations of
structure which are confessedly additions to or subtractions from
the characters of ancestors, which have appeared during ordinary
descent. The j^rotean species, genera, etc., are well known to
biologists, and every naturalist who admits varieties, sub-species,
sub-genera, etc., admits derivation so far as they are concerned.
The facts of variation, including ''^sporting," etc., are notorious,
not only among domesticated, but also in wild animals and plants.
The facts have led some persons to suggest that species have been
produced by evolution from a single specific center, but that the
genus and other comprehensive divisions are unchangeable. But
I think I have shown, in a paper entitled " The Origin of Gen-
era," * that the structural characters which define genera, and even
higher divisions, are subjects of variation to as great an extent as
are the less profound specific characters ; and, moreover, that the
evidence of derivation which they present is singularly clear and
conclusive. The changes of both genus and species character are
always of the nature of additions to or subtractions from those of
one generation displayed by their descendants. As such, they
form the closing chapters of the embryonic or growth-history of
the modified generation.

In order to explain more fully the application of the above
statements, I introduce a few examples selected from the subjects
of my studies. Their number might be indefinitely extended. I
first cite the genera of the tailless BatracMa Anura (frogs, toads,
etc.), whose relations are very simple and clear, and show the
parallelism between adult structure and embrj^onic succession. See
above, 1 and 2.

The greater number of BatracMa Anura fall into two divis-

* Philadelphia, 1869. "Proceedings Academy Natural Sciences, 1868."

REVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 217

Fig. 8.

Fig. 9.

ions, which differ only in the structure of the lower portion of
their scapular arch, or shoulder-girdle. In the one the opposite
halves are capable of movements which contract or expand the
capacity of the thorax; in the other the opposite halves abut
against each other so as to be incapable of movement, thus pre-
serving the size of the thoracic cavity. But during the early
stages, the frogs of this division have the movable shoulder-girdle
which characterizes those of the
other division, the consolidation con-
stituting a modification superadded
in attaining maturity. Further-
more, young Amir a are toothless,
and one section of the species with
embryonic shoulder-girdle never ac-
quire teeth. So here we have a
group which is imperfect in two
points instead of one. This is the
tribe Bufoniformia; the tribe with
teeth and embryonic shoulder-girdle
is called the Arcifera, and that
which is advanced in both these res-
pects is the Raniformia. Now the
frogs of each of these divisions pre-
sent nearly similar scales of develop-
ment of another part of the skeleton,
viz., the bones of the top of the skull.
We find some in which one of these
bones (ethmoid) is represented by
cartilage only, and the frontoparietals
and nasals are represented by only a
narrow strip of bone each. In the
next type the ethmoid is ossified ; in
the next, we have the frontoparietal
completely ossified, and the nasals
range from narrow strips to complete
roofs ; in the fourth station on the
line, these bones are rough, with a hyperostosis of their surfaces ;
and in the next set of species this ossification fills the skin, which
is thus no longer separable from the cranial bones ; in the sixth
form the ossification is extended so as to roof in the temporal
muscles and inclose the orbits behind, while in the rare seventh

Fig. 10.

SlIOULDEK-GIRDLES OF " AnURA."

Fig. 8, of the Arciferous type
(Scaphiopus holbroohi). Fig. 9,
Rana temporaria^ tadpole -nith
budding limbs. Fig. 10, do. adult.
Figs. 9 and 10 from Parker.

218 GENERAL EVOLUTION.

and last stage, the tympanum is also inclosed behind by bone.
Now all of these types are not found in all of the families of the
Anura, but the greater number of them are. Six principal fami-
lies, four of which belong to the Arcifera, are named in the dia-
gram below, and three or four others might have been added. I
do not give the names of the genera which are defined as above
described, referring to the explanation of the cuts for them, but
indicate them by the numbers attached in the plate, which corres-
pond to those of the definitions above given. A zero mark signi-
fies the absence or non-discovery of a generic type.

Sternum

embryonic.

Sternum complete.

Bufoniformia.
Bufonidae.

Arcifera.

Eaniformia.

Scaphiopidse
and Pelobatidae.

Cystignathidse.

Hylidae.

Eanidae.

1—

2—

3—

4—

5—

6—

1—

It is evident, from what has preceded, that a perfecting of the
shoulder-girdle in any of the species of the Bufoniform and Ar-
ciferous columns would place it in the series of Eaniformia. An
accession of teeth in a species of the division Bufonifor?ma would
make it one of the Arcifera j while a small amount of change in
the ossification of the bones of the skull would transfer a species
from one to another of the generic stations represented by the
numbers of the columns from one to seven.

There are few groups where this law of parallelism is so readily
observed among contemjoorary types as the Batracliia, but it is
none the less universal. The kind of parallelism usually observed
is that in which there is only a partial resemblance between adults
of certain animals and the young of others. This has been termed
*^ inexact parallelism," and the relation is presented by forms not
very nearly phylogenetically related. The more remote the phylo-
genetic lines of two types, the more *"' inexact " will their parallel-
ism be. It was once a question whether any parallelism can be
traced between the members of the five or six primary divisions of
animals, and in my essay on the *^ Origin of Genera," I was com-
pelled to state that there was then ^'no evidence of the community

KEVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 219

of origin of these diyisions." Since that time, Haeckel has pub-
lished his '^Gastraea Theory." This is a grand generalization
from the facts of embryology, which shows the community in
type of the early stages of all animals, and the similarity of the
phases which they present during a part of their larval life. The
exceptions to this law which have been
observed will probably be explained, as
have been those which have been urged
against the law of homologies in anatomy.
The paleontology of the Batracliia
anura is largely unknown, so we must
look elsewhere for proof of the truth of
the fourth proposition, viz., that the suc-
cessional relation in embryology corre-
sponds with that shown by paleontology
to have existed in geologic time.

For this purpose I select one of the
most complete series
known to paleontology;
that of the camels or
CameUdcB, whose re-
mains are found abund-
antly in various parts
of our country. The
succession of the known
genera is seen in the
structure of the bones
of the feet, and of the
superior incisor and
premolar teeth. The
metatarsal and meta-
carpal bones are or are
not co-ossified into a
cannon bone ; the first
and second superior in-
cisor teeth are present,
rudimental or wanting,
and the premolars num-
ber from four to one.
The relations which
these conditions bear

Fig. 11.

Fig. 12.

Fig. W.—Poebrotherium vilsoni carpus and meta-
carpus with end of radius, three fifths natural size.
Original ; from White Eiver Miocene of Colorado.

Fig. 12.— Carpus and metacarpus of Procamelus
occidentalism about two fifths natural size. Original ;
from report of G. M. Wheeler, U. S. Expl. Surv. W. ot
100th Mer., vol. iv, pt. ii. From New Mexico.

PLATE IV.

Fig. 1.

Fio. 33.

Fig. 2.

Fig. 3, wanting.

FjG. 5.

Fig. 6.

Fig. 7.
BUFONID^.

Fig. 7, wanting.
SCAPHIOPIDJE AND PELOBATIDM.

PLATE V.

Fig. 1.

Fig. 2.

Fig. 3.

Fig. 83.

Fig. 32.

Fig. 3 1.

Fig. 3.

Fig. 31.

Fig. 32.

Fig. 4.

Fig. 33.

Fig. 6.

Fig. 6.
CYSTIGNATHID^.

Fig. 5.
RANID^.

222 GENEKAL EVOLUTION.

EXPLANATION OF CUTS OF CRANIA OF ANURA.

The numbers in each column correspond with the types of ossification mentioned
in the text, and are the same as those in the table of families given in the same con-
nection. The power numbers attached to Fig. 3, represent the degree of ossification
of the nasal bones, except the ~\ which signifies unossified ethmoid. Most of the
cuts are original.

BcFONiDJE. — Fig. 2, anterior part of skull of Chdydohairachas gouldi Gray, from
Australia. Fig. 3, do. of Schismaderma carens Smith, S. Afi"ica. Fig. 6, top
of head of Peltaphryne peltacephala D. and B., Cuba. Fig. 7, top of head of
Otaspis empusa Cope, Cuba.

SoAPHiopiD^ AND Pelobatid^. — Fig. 2, diagram of top of cranium of Didocus
ccdcaratus Micahelles, Spain. Fig. 5, skull of Scaphiopm liolhroolci Harl.,
United States. Fig. 6, skull of Cultripes provincialis, from France, after
Duges.

llYLiDiE. — Fig. 1, Thoropa miliaris Spix., Brazil. Fig. 2, Hupsiboas doumerci D.
and B., Surinam. Fig. 2\ Hypaihoas punctatus Schn., Brazil. Fig. 3^, Scytopis
vemdosus Daudin, Brazil. Fig. 6, Trachycephalus geographicus D. and B.,
Brazil, after Steindachner.

Cystignathid^. — Fig. 1, Eusophus nehuloaiis Gir., Chili. Fig. 2, Borhoroccetes tas-
maniensis Gthr., Tasmania. Fig. 3, Elosia nasiis Licht., Brazil. Fig. 3^, Ify-
lodes oxyrhyiichus D. and B., W. Indies. Fig. 4, Grypiscus umbrinus Cope,
Brazil. Fig. 6, Calyptocephalus gayi D. and B., Chili.

Ranid^. — Fig. 3~^ — Ranula chry&oprasina Cope, Costa Rica. Fig. 3, Rana oxy-
rhyncha Sund., S. Africa. Fig. 3\ Rana clamata Daud., N. America. Fig. 3^,
Rana agilis Thomas. Fig. 3'^, Rana hexadactyla Less., India. Fig. 4, PoJy-
pedates quadrilineatus D. and B., Ceylon.

to geologic time are displayed in the follo^^ng table, commencing
with the lowest horizon :

No cannon bono. Cannon bone present.

Incisor teeth present. Incisors one and two wanting

4 premolars, 3 prem'rs. 2 prem's. 1 prem'r.

Lower Miocene. -] Pochrotherium.

{ Protolahis.

Upper Miocene. < Procamelus

Pliocene and Recent.

( Pliauchenia.

Camelus.

Auchenia.

This table shows that geological time has witnessed, in the his-
tory of the CamelidcB, the consolidation of the bones of the feet
and a great reduction in the numbers of the incisor and premolar
teeth. The embryonic history of these parts is as follows : In the

REVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 223

foetal state all the Ruminantia (to which the camels belong) have
the cannon bones divided as in Poehr other ium ; they exhibit also
incisor teeth, as in that genus and Protolabis. Very young recent

Fig. 13. — Protolabis Iransmontanus Cope, skull, a, in profile ; 5, from below, one
third (linear) natural size. Original; from vol. iv, Report U. S. Geol. Surv., under
F. V. Hayden. Ticholeptus bed of Oregon.

camels have the additional premolar of Pliauchenia. They shed
this tooth at an early period, but very rarely a camel is found
in which the tooth persists. The anterior premolar of the normal

Fig. 14. — Procamelus occidentalis Leidy, profile of skull, about two sevenths natu-
ral size. Original ; from report of Capt. G. M. Wheeler, IT. S. Geol. Geog. Surv. W.
of 100th Mer. Vol. iv, pt. ii. From Loup Fork bed of New Mexico.

Camelus is in like manner found in the young lama (Auchenia),
but is shed long before the animal attains maturity. I may add
that in some species of Procmnelus caducous scales of enamel

224: GENERAL EVOLUTIOIN".

and dentine in shallow cavities represent the incisive dentition of
Protolabis.

It remains to show that characters of the kind above men-
tioned are sometimes inconstant ; that they may or may not ap-
pear in individuals of a species. Under such circumstances it is
evident that their origin does not imply any break in the line of
descent.

First, as to a family character. It is well known that the deer
differ from the giraffes in the presence of a burr or ring of osseous
excrescences surrounding the base of the horn. Now, in the ex-
tinct tertiary genus Cosoryx there are three species which possess
or lack this burr indifferently. Why some individuals should,
and others should not possess it, is not known.*

Second, as to a generic character. The genus Canis (dog) is
defined by the presence of two tubercular molars in the inferior
series. The allied genus Tlious possesses three such teeth, while
Idicyon has but one. Kow examples of Canis familiar is (domes-
tic dog) with but one tubercular molar are not rare, while an in-
dividual with three is occasionally found.

To take another case. The normal dentition of Homo (man)
is, on each side, incisors, 2 ; canine, 1 ; premolars, 2 ; molars, 3.
It is very common to find in the higher races, individuals who
have molars only two in one or both jaws ; and the absence of
the external incisors of the upper jaw is almost as frequently met
with. Here we have two new generic variations in one and the
same species.

In specific characters variations are most familiar. Thus, the
young of deer are generally spotted, and the adults are nearly
uniform in coloration. Some deer (as the Axis) retain the spotted
coloration throughout life, while an occasional spotted individual
of unicolor species is a violation of specific character by a failure
to develop. The larvae of some salamanders are of uniform col-
oration, and the adults spotted. The unicolor adults of the same
species, not uncommonly met with, present examples of the same
kind of variation.

Any biologist can select hundreds of similar cases from his
special department of study.

* The explanation I have offered is that the horn was stripped of its integuments
to the position of the burr by the animals in fighting. The condition of the speci-
mens renders this hypothesis pi'obable. See "Report U. S. Expl. Surv. W. 100th
Mer.," Capt. G. M. Wheeler, vol. iv, pt. ii.

EEYIEW OF THE MODERN DOCTRmE OF EYOLUTIOIT. 225

II. THE LAWS OF EVOLUTIOIT.

Having reviewed the reasons why the doctrine of evolution
should be received as truth, I desire to give attention to the laws
which may be made out by reference to its phenomena. Progress
in this direction is difficult, owing to the natural impediments in
the way of studying the history of the growth of living beings.
We will, however, commence by examining more fully the phe-
nomena with which we have to deal.

It is well understood that the world of animal life is a nicely
adjusted equilibrium, maintained between each individual and its
environment. This environment exerts forces both purely physi-
cal, and those exercised by other animals. Animals antagonize
each other in procuring food, whether that food consist of vegeta-
tion or of other animals, but in the latter case the conflict is more
severe. A similar competition exists among male animals in the
matter of reproduction. These exhibitions of energy constitute
the struggle for existence, which is the daily business of the living
world. It is well understood that in this struggle the individuals
best provided with means of self-preservation necessarily survive,
while the weak in resources must disappear from the scene.
Hence those which survive must display some especial fitness for
existence under the circumstances of their environment, whatever
they may be. So the ^^ survival of the fittest" is believed to be a
law of evolution, and the process by which it is brought about has
been termed ** natural selection." The works of Darwin and
others have satisfied biologists that this is a vera causa.

Before the excellence of a machine can be tested, it must exist,
and before man or nature selects the best, there must be at least
two to choose from as alternatives. Furthermore, it is exceedingly
improbable that the nicely adapted machinery of animals should
have come into existence without the operation of causes leading
directly to that end. The doctrines of **^ selection " and "sur-
vival " plainly do not reach the kernel of evolution, which is, as I
have long since pointed out, the question of "the origin of the
fittest." The omission of this problem from the discussion of
evolution, is to leave Hamlet out of the play to which he has
given the name. The law by which structures originate is one
thing ; those by which they are restricted, directed, or destroyed,
is another thing.

There are two kinds of evolution, progressive and retrogres-
15

226 GENERAL EVOLUTION.

sive ; or, to use expressions more free from objection, by addition
of parts, and by subtraction of parts. It is further evident that
that animal which adds something to its structure which its par-
ents did not possess, has grown more than they ; while that
which does not attain to all the characteristics of its ancestors has
grown less than they. To express the change in the growth-his-
tory which constitutes the beginning of evolution, I have employed
the terms *^ acceleration and retardation." Generally these ex-
pressions are literally exact, i. e., there is an increased rate of
growth in evolution by addition, and a decreased rate in evolution
by subtraction ; but this is not always the case, for some divisions
of animals have increased the length of their growth-period with-
out reference to evolution in structure. The terms express the
phenomena figuratively, where not exact in the sense of time, and
I believe they are sufficiently clear. The origin of the fittest is
then a result of either acceleration or retardation. It is easy to
perceive that a character which makes its appearance in a j^arent
before or near to the breedino^ season is likelv to be transmitted to
its descendants ; so also a character which is lost near this time is
likely to be wanting from the offspring. The causes of accelera-
tion and retardation may next claim attention.

It is well known that the decomposition of the nutritive fluids
within living animals gives rise, in the appropriate tissues, to
exhibitions of different kinds of forces. These are, motion in all
classes ; heat in some only ; in a still smaller number, electricity
and light ; in all. at certain times, growth-force or bathmism ; in
many, phrenism or mental or thought-force. These are all derived
from equivalent amounts of chemical force which are liberated by
the dissolution of protoplasm. This organic substance, consisting
of CHON, undergoes retrograde metamorphosis, being resolyed
into the simpler CDs, HO, etc., and necessarily liberates force in
the process. None of the functions of animal life can be main-
tained without supplies of protoplasm. TVe have here to do with
bathmism. It consists of the movement of material to, and its
deposition in, certain definite portions of the growing egg, or
foetus, as the case may be. It is different in its movements in
every species, and its direction is probably the resultant of a num-
ber of opposing strains. In the simplest animals its polar equili-
brium is little disturbed, for these creatures consist of nearly
globular masses of cells. As we ascend the scale a greater and
more marked interference becomes apparent ; radiated animals

REVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 227

display energy in a number of radiating lines rather than in the
spaces between them ; and in longitudinal animals, a longitudinal
axis exceeds all others in extent and importance. In the highest
animals its results are much more evident at one extremity of the
axis (head) than at the other, and the diyerging lines are reduced
to four (the limbs). In each species the movements of this force
are uniform and habitual, and it is evident that the habit is so
deeply seated that only a very strong dynamic interference can
modify or divert it. The interfering forces are probably all those
transmissible through living tissue, and especially molar force.
Thus every species has its own specific kind of bathmic force.

The characters of living beings are either adaptive or non-
adaptive ; they are either machines especially fitted to meet the
peculiarities of their environment, or they are not. Among the
latter may be ranged rudimental structures and also many others
of no sufficient use. They are all due either to excess or defect of
growth-force ; they are either consequences of a removal of nutri-
tive material to other portions of the body ; or they are due to an
excess of such material which renders an organ or part useless
through disproportionate size. Of the former class may be cited
the absence of the tail in some monkeys and birds ; also of the
teeth in some Cetaceans ; of the latter kind are the enormous
tusks of the mammoth and the recurved superior canines of the
bab}Tussa. The change of destination of this material has been
probably due to the construction of adaptive machines whose per-
fection from time to time has required the use of larger and larger
proportions of force and material.

In considering the origin of adaptive structures, two alterna-
tive propositions are presented to us. Did the occasion for its use
follow the appearance of the structure, or did the need for the
structure precede its appearance ? The following answer to the
question has always been the most intelligible to me. Animals
and plants are dependent for existence on their environment. It
is an every-day experience that changes in environment occur
without any preparation for them on the part of living things. If
the changes are very great, death is the result. It is evident that
the influence of environment is brought to bear on life as it is, or
has been, and that special adaptations to it on their part must fol-
low, not precede, changes of climate, topography, population, etc.
We have another important consideration to add to this one, viz.,
the well-known influence of use, i. e., motion, on nutrition. Ex-

228 GENERAL EVOLUTION.

ercise of an organ determines nutritive material to it, and the
nervous or other influence which does this, equally determines
nutritive material to localities in the body to which an effort to
move is directed, whether an executive organ exist there or not.
The habit of effort or use determining the nutritive habit must be
inherited, and result in the growing young, in additional struct-
ure. Change of structure, denied to the adult on account of its
fixity, will be realized in the growing or plastic condition of foetal
or infant life. The two considerations here brought forward lead
me to think that the cause of acceleration, in many adaptive
structures, is environment alone, or environment producing move-
ments, which in turn modify structure. The character of the
stimulus in the successive grades of life may be expressed by the
following table, passing from the lowest to the highest :

1. Passive or motionless beings :

by climate and food only.

2. Movable beings :

by climate, food and motion.
By motion either :
a, unconscious, or *
aa, conscious, which is,

h, reflex, or
M, directed by desire without ratiocination, or
Mb, by desire directed by reason.

The only general rules as to the direct influence of motion on
structure which can be laid down at present are two, viz., That
density of tissue is in direct ratio to pressure, up to a certain
point ; t and that excess of growth-force, in a limited space, pro-
duces complications of the surfaces stimulated. \ These and other
laws, yet unknown, have probably led the changes expressed by
evolution, while many others have followed the disturbance of
equilibrium which they have produced.

I here allude incidentally to the question of transmission or
inheritance. It has been maintained above that the bathmic force
of each species is different from that of all other sj^ecies. This
force is characteristic of some unit of organization of living be-

* Movements coming under this head are often called reflex,
•f- See "Penn. Monthly," 1872; this work Art. L
X " Method of Creation," Philadelphia, 1871.

EEVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 229

ings ; and this probably consists of several molecules. This unit
has been termed, by Haeckel, the plastidule. The transmission
of the bathmic force of one generation to another would be effected
by the transmission of one or more living plastidules ; and this is
probably precisely what is accomplished in reproduction. The
Dynamic Tlieory of reproduction I proposed in 1871,* and it has
been since adopted by Haeckel under the name of perigenesis. I
compared the transmission of bathmic force to that of the phe-
nomenon of combustion, which is a force conversion transmitted
from substance to substance by contact. The recent observations
of Hertwig, Biitschli and others, confirm this view. The theory
of pangenesis, devised to explain the phenomenon of rej^roduction,
is to my mind quite inadequate.

III. METAPHYSICS OF EVOLUTION".

I enter here upon a wide field, over which I can only skim on
an occasion like the present. The subject has been already intro-
duced by reference to consciousness as modifying movement ; of
course, then, if movement modify structure, the latter is influenced
by consciousness. The word consciousness was then, and is now,
used in its simplest sense, viz. : as synonymous with physical
sensibility. Its lowest and most usual exhibition is the sense
of touch ; the special senses, taste, sight, etc., are higher forms,
while thoughts and desires are organized products of the same raw
material. Consciousness can not be denied to many of the inferior
animals ; indeed, if we grant it to any, we must admit that it is
displayed at times by even the lowest Protozoon. That these
humble creatures should possess it, is apparently quite as proba-
ble as that the very similar bioplasts of the brain of man should
be its seat.

Consciousness alone is not a sufficient basis for the develop-
ment of mind. For this, one more element is necessary, and that
is, memory. Impressions made by the environment are registered,
and soon cease to be present in consciousness. Under the influ-
ence of association the impressions return to consciousness. Asso-
ciations are those of place, of the order of time, and of similarity
or difference in various qualities, as size, color, or any other physi-
cal features. Experiences of these qualities are to all conscious
beings either painful, indifferent, or pleasurable. When associa-

* "Method of Creation," 18V1.

230 GENERAL EVOLUTION.

tion requires, events, objects, or cliaracteristics, are returned to
consciousness in the order in which they cohere most firmly in
the mind, which may or may not be that in which they entered it.
The liking for or dislike to the object, are equivalent to an attrac-
tion to or repulsion from it. Thus experience is begotten : as its
material increases, new combinations are formed, new relations
observed, and in the highest tyipes of mind, laws are discovered.
No one can deny memory to animals ; it is the medium of their
education by man, and has been as well the means of their edu-
cation by nature. Impressions cause a re-arrangement of cer-
tain elements of structure which give the form to consciousness
when it arises again. It is also probable that these arrangements
are not the same as those which represent classifications and con-
clusions, but that nevertheless the arrangement or organization
of these is determined by the simpler arrangements caused by
perceptive stimuli. Experience produces these combinations in
the bioplastic aggregations of all animals, be they in the form of
ganglia, brains, or less specialized forms. Nowhere in the human
organism are the effects of effort and use so strikingly witnessed
as in the increase of brain power ; and familiarity with the educa-
tion of the lower animals shows that this is the case with them
also, though in a lesser degree than in man.

If, then, we grant the p^ropositions, first, that effort and use
modify structure ; and second, that effort and use are determined
by mind in direct ratio to its development, we are led to the con-
clusion that evolution is an outgrowth of mind, and that mind is
the parent of the forms of living nature. This is, however, to
reverse a very usual evolutionary hypothesis, viz. : that mind is
the product and highest development of the universe of matter
and force. The contradiction is, however, not so absolute as at
first appears. By mind, as the author of the organic world, I
mean only the two elements, consciousness and memory. But it
is the view of some thinkers that consciousness is a product ; that
it is not only a correlative of force, but a kind of force. To the
latter theory I can not subscribe ; when it becomes possible to
metamorphose music into potatoes, mathematics into mountains,
and natural history into brown paper, then we can identify
consciousness with force. The nature of consciousness is such
as to distinguish it from all other thinkable things, and it
must be ranged with matter and force as the third element of the
universe.

EEVIEW OF THE MODERN" DOCTRINE OF EVOLUTION. 231

It is true that unconsciousness does not imply absence of life
as generally understood. A majority of the processes of life are
performed unconsciously by living creatures ; mind itself being
no exception to this rule. There is another class of acts whose
performance produces sensation, but consciousness is not con-
cerned in. them as an immediate cause. Therefore, it is a com-
mon endeavor to associate reflex and unconscious acts with the
molecular movements of inorganic and non-living substances.
But the one great difficulty in making this identification has
never been surmounted. This is the different nature of the
movements in the two cases. In non-living matter they are sim-
ply polar, nothing more. In living beings they display design.
Perhaps I use the word *^ design " in a new sense, but the expres-
sion is nevertheless appropriate. What I mean is, that the move-
ments of living things have direct reference to consciousness, to
the satisfaction of pleasures, and to the avoidance of pains. The
molecular movements within animals of the simplest class are the
digestion of food and the elaboration of the materials of repro-
duction. The molar movements of the simplest animals are to
enable them to escape the pains of hunger and celibacy. More-
over there is reason why the movements of living beings display
design. We all know the nature of habits ; how they are per-
formed unconsciously, and as automatically as digestion itself.
But did any one ever know of a habit in an animal, whose origin
he could trace, which has been formed in unconsciousness ? Ac-
cording to our knowledge, habits are always the result of stimuli
which are consciously felt, and which cause by repetition or
through reminiscence a repetition of the resulting movement.
After a sufficient number of rej^etitions such an act becomes a
habit, i. e., is performed automatically, or without the interven-
tion of effort, and frequently without consciousness. It thus be-
comes a part of the character of the individual or species. This
common phenomenon is explained by the hypothesis that an or-
ganization of the centers controlling action is caused by the efforts
of the animal under the stimulus, and that finally a machine is
constructed which determines the nature of the force expended,
without further mental exertion of the individual. Such a pro-
cess is education, and the result is an addition to the stock of
faculties already on hand. Thus is explained the vast number of
automatic and unconscious activities displayed by animals ; to the
same source, I believe, the common reflex acts may be traced ; it

232 GENERAL EVOLUTION.

even appears to me probable that the organic functions in general
have had the same origin.* While these latter have mostly long
since passed beyond the control of the mind, portions of the uro-
genital functions still linger within the confines of its jurisdiction.
Thus have consciousness and mind endowed living nature with
useful functions ; and this, which may be called the Theory of
Endoiument, accounts for the element of design which is so puz-
zling when seen in unconscious and reflex acts.

As it has been maintained above, that structure is the effect of
the control over matter exercised by mind, it is evident that the
evolution of mind must be directly followed by corresponding de-
velopment of organism. The science of paleontology substantiates
this theory in a wonderful manner. But the animal mind being
generally occupied with simple functions, its expressions in struct-
ure are usually nothing more than the progressive creation of im-
proved instruments for obtaining food, resisting climate, escaping
enemies, and reproducing their kind. The struggles of animals
have been seen on this j^latform, and mind has only been necessary
to aid in accomplishing the ends above mentioned. AYonderfully
effective machines for grinding, cutting, seizing, and digging ; for
running, swimming, and flying have been produced. The develop-
ment of mind proper must appear in the size and structure of the
brain ; and though the history of the latter in past ages must
always remain, in large part, hidden from us, it is known that in
the former respect there has been great progress made in various
lines of animals. Now the line which has carried brain to its pres-
ent development in man, the Quadrumana, has been deficient in
special mechanical excellencies of the kind enumerated above.
Perhaps primitive inferiority in these many respects has kept the
Quadrumana under greater mental tension, and compelled them
to exercise caution in their acts, and give that opportunity to
thought which was less demanded in the case of other animals.
Furthermore, if they are less specialized in their mechanism than
most other Mammalia, they are less restricted by it to peculiar
modes of life. They are more versatile, and more capable of the
adoption of new habits as a consequence. And here we have a
glimpse of a most important principle in evolution, which is the
keynote to its method ; this is what I have called the The Doctrine
of the Unspecialized.

* " Consciousness in Evolution." " Penn Monthly," 1875.

REVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 233

Paleontology shows that the succession of living types has not
been in a. single straight line. It has been in many divergent lines,
and a large number of them have not continued to the present
time. The history of life has been well compared to a tree with
divergent branches, many of which do not reach the elevation of
the summit. Furthermore, in the many cases in which we can
trace the lower lines to the present period, it is evident -that in
- their present condition they could not have given rise to the higher
forms. Each line, in fact, has developed to an extreme of spe-
cialization of structure, which it would seem is incapable of modifi-
cation in any direction very divergent from that which it has al-
ready taken. Much less have such specialized types been able to
survive the environment for which they were designed ; with im-
portant changes in that respect they have perished. A few exam-
ples will serve to illustrate my meaning. The direction of develop-
ment has been from fishes, through BatracMa and rei)tiles, to birds
and mammals. But we can not derive any living type from the
osseous fishes of the present or past ages {Teleostomi): to find the
origin of BatracMa, we must pass below these to more generalized
and older forms, the Dipnoi, a class whose position in the system
was for years a controverted point. We can not obtain Mammalia
from any of the existing types of reptiles, but we must go back to
the Permian period, and trace their outlines in the Tlieromorplia
of that day. In spite of the prophetic resemblance of these
remarkable animals, they are inferior to later Eeptilia in the
structure of their vertebral column, and display resemblance to
some of their immature stages, as well as to those of the Mammalia.
Among mammals we can not derive monkeys from Carnivora or
Ungulata, nor the latter from each other, but can only trace their
close approximation in the Bunotherian types of the Lower Eocene.
So with the great divisions of Ungulata ; Prohoscidians, Hyrax,
and the even- and odd-toed orders must all be traced to the un-
specialized AmUijpoda, with small brains and five-toed plantigrade
feet, as their ancestors.* It is easy to perceive that the generali-
zation and plasticity of all these forms has furnished the ground
of their ancestral relation.

"We are now in a position to comprehend more clearly the
general nature of evolution. The doctrine of the unspecialized

* See the origin of types of Mammalia educabilia, " Journal Academy," Philadel-
phia, 1874.

234: GENERAL EVOLUTION.

teaches that the perfection produced by each successive age has
not been the source or parent of future perfection. The types
which have displayed the most specialized mechanism have either
passed away, or, undergoing no change, have witnessed the prog-
ress and ultimate supremacy of those which were once their infe-
riors. This is largely true of animals which have attained great
bulk. Like those with perfected weapons, they have ever been
superior to the attacks of other animals in their day, and doubt-
less led, so long as food abounded, lives of luxurious indolence.
With change or diminution of food, such huge beasts would be
the first to succumb, and it is a fact that no type of land animals
has maintained great size through many geologic changes. It is
true that all of the lines of ancestry of the existing higher Mam-
malia, as the subdivisions of the Carnivora, Ungulata, and Quad-
rumana, which we know in detail, commenced with types of
small size and correspondingly little muscular power.

Some important conclusions may be derived from what has
preceded. It seems that evolution has witnessed a continual run-
ning down of types to their great specialization or extinction.
That many types have arisen in weak and small beginnings, but
that the conflict with more powerful forms has developed some
qualities in which they sooner or later excelled, and which formed
the basis of their future superiority and persistence. That while
this has probably been the true cause of the origin of the many
admirable mechanical adaptations displayed by animals, it is pre-
eminently true of the development of mind. That the reason
why progress has reached its limit in the lines of greatest speciali-
zation, has probably been the removal of the occasion of its origi-
nal cause, i. e., active exercise in the struggle for existence. This
explanation is suggested by the remarkable degradation which is
witnessed in animals whose mode of life relieves them from the
necessity of working for a livelihood, e. g., the parasites and ses-
sile animals whose young are free. Some of these creatures, on
assuming their parasitic life, lose the semblance of even the order
to which their young belong. The primary stages of various
plants move acti^^ely through the water like the lowest forms of
animals, and their sessile adult condition must be looked upon as
a degeneration. It is well known that the endeavor to relegate
the lowest forms of life to the two kingdoms of animal and vege-
table, has been generally abandoned. The great vegetable king-
dom probably exhibits a life degraded from more animal-like be-

KEVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 235

ginnings. Animal irritability and mobility have been lost, and
their own consciousness must be entirely eliminated from the
question of the origin of the many later and specialized types of
plants. But I venture here the hypothesis that the consciousness
of plant-using animals, as insects, has played a most important
part in modifying the structure of the organs of fructification in
the yegetable kingdom.* Certain it is that insects have been
effective agents in the preservation of certain forms of plants. I
would suggest whether the mutilations and strains they have for
long periods inflicted on the flowering organs, may not, as in some
similar cases in the animal kingdom, have originated peculiarities
of structure.

Evolution of living types is then a succession of elevations of
l^latforms on which succeeding ones have built. The history of
one horizon of life is, that its own completion but prej^ares the
way of a higher one, furnishing the latter with conditions of a
still further development. Thus the vegetable kingdom died, so
to speak, that the animal kingdom might live ; having descended
from an animal stage to subserve the function of food for animals.
The successive types of animals have first stimulated the develop-
ment of the most susceptible to the conflict of the struggle for
existence, and afterward furnished them with food. Doubtless,
in the occupation of the world's fields, the easiest and nearest
at hand have been first occupied, and successively those which
were more difficult. The digging animals are generally those
which first abandoned the open field to more courageous or
stronger rivals ; and they remain to this day generally of low type
compared with others of their classes (e. g., Monotremata, Roden-
Hay Insectivora). All occupations have been filled before that one
which requires the greatest expenditure of energy, i. e., mental
activity. But all other modes of life have fallen short of this one
in giving the supremacy over nature.

Automatism then represents a condition of ^'lapsed intelli-
gence" and diminished life. The unconscious automatism of
animals is a condition of still greater lapse. On the contrary,
sensibility is the condition of development, and the susceptibility
and impressibility which is the extreme reverse of automatism is
the especial character of youth. Here the " doctrine of the un-
specialized" finds justification again.

* This opinion has also been expressed by Hermann Miillcr.

236 GENERAL EYOLUTIOK

What the future has in store for us in the history of inorganic
force and its results we can not now foresee, but I call attention
in this connection to the important part played by life in the dis-
tribution of minerals. It has long been known that the carbon of
the earth's crust was once in a living state, and it is admitted that
the limestone once circulated in the fluids of animals. We have
recently been compelled to believe that siliceous rocks are com-
posed of the consolidated shells of minute plants, which they have
elaborated from the water of the ocean. Silver and gold are seg-
regated and deposited by seaweeds. The principal rock material,
whose relation to life has not been ascertained, is alumina. How
far the processes which now characterize dead matter were once
related to life is a problem for the future.

IV. THE MORALS OF EVOLUTION?".

The doctrines of the struggle for existence and survival of the
fit in human life have a two-fold application. The relative pro-
portions in which these applications are made will depend on the
moral development of him who makes them. Moral density and
intellectual stupidity (often nearly allied) will see in these two
laws only the struggle for material power, and the survival of the
strongest. They will hardly urge in these days, as they would
infallibly have done had they lived a few centuries ago, that the
strongest means the hardest hitter, or the most successful assassin,
but they will probably believe that this pre-eminent ]oosition be-
longs to the most wealthy. From a purely dynamical standpoint
this position is correct, yet it might be a useful question for such
advocates to consider why it is that physical oppression and assas-
sination should be less successful avenues to power than they once
were.

There, are two reasons why man does not grant the first place
in his esteem to physical force. The first principles of morals are
acquired in the struggle for existence* The idea of meum and
tuujYi was speedily developed so soon as men associated together ;
and the habit of justice has doubtless been formed by the insist-
ence of every man on his own rights, and by the power of combi-
nations of men to control those who may from superior strength
or other cause seek to violate the rights of property. Thus law
originated, and from the earliest history of the race to the present
day it has educated the barbarous and semi-barbarous to civiliza-
tion. It is then easy to perceive that man gives the highest place

EEVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 237

in his affections to the most just ; but there is yet another reason
why this should be the case.

The reproductive instinct in the lower animals has developed
into social affections, and these form a part of the character of
the higher animals and, in an especial degree, of man. The senti-
ments of sympathy and benevolence are j^robably outgrowths of
the same. While the rational faculties are concerned in the
knowledge of right, these sentiments are a source of the love of
right. This disposition is trusted by men as leading to ihQ prac-
tice of right, in cases where the power to enforce it is not immedi-
ately present. The struggle for existence then among men ranges
all the way from a rivalry of physical force to a rivalry for the
l")OSsession of human esteem and affection. The robber and assas-
sin of the lowest human races are represented by the slanderer and
defamer in the higher. The ultimate prosperity of the just, as-
serted and foretold by prophets and poets, is but a forecast of the
doctrine of the survival of the fittest. The unjust are sooner or
later eliminated by men from their society, either by death, seclu-
sion, or ostracism.

But the organized moral qualities can not normally transcend
in power, as motives of human action, those which secure man's
physical preservation. Lines of men in whom the sympathetic and
generous qualities predominate over the self-preservative, must
inevitably become extinct. Evolution can produce no higher de-
velopment of the race (whatever may sometimes appear in indi-
viduals) than an equivalency in these two classes of forces. Be-
yond this the organization of the social faculties of the brain must
always be repressed in the race, so that we can only expect to
attain an equilibrium between them and the more purely selfish
ones, as the very highest result of unassisted evolution. In this
position the judgment is suspended between the opposing classes
of motives ; and it must ever remain doubtful in general as to
whether resulting action will be just and right, or the reverse. I
exclude from this question those generous acts which do not appear
to the actor to conflict with self-interest. These may be termed
sympathetic acts, and are quite distinct from the altruistic* The
sympathetic actions are seen at times in most animals. The al-
truistic acts, on the other hand, are those that express what is usu-
ally called ''moral principles." Sach acts may often coincide

* " On the Origin of the Will." " Penn Monthly," 1877.

238 GENERAL EVOLUTION.

with the interest of the actor, but so long as they do not appear
to him to do so, they are altruistic. It is part of the doctrine of
evolution that habits will ultimately disappear on the removal of
their stimulating cause. The moral nature originated, and has
been maintained, through the pressure of the fear of consequences.
The removal of this pressure, through the acquisition of power,
would then ultimately result in the diminution or loss of the moral
nature, through disuse. The abuses of power are well known.
This appears to be all that evolution can do for us in the produc-
tion of the moral nature. So it would appear that no organized
faculty of self-sufficient altruistic justice can be derived by the
process of mental evolution. The result is rather a continued
struggle between justice and injustice. It is, then, evident that
any power which shall cause the permanent predominance of the
just over the selfish faculties must be derived from without.

After we omit from customary religion, cosmogony, which be-
longs to science, and theogony, which belongs to the imagination,
we have left an art which has for its object the development and
sustentation of good works or morals among men. If the teachers
and professors of this art produce the results in this direction at
which they aim, their great utility must be conceded by all. Their
method has the advantage over that of the law, in being of the
character of inducements supplied before action, instead of pains
and penalties inflicted after action. They strive to originate good
conduct, rather than to punish bad conduct. They are working
on the side of the originative force in development, rather than
the destructive ; the '^origin of the fittest y^' rather than the '^sur-
vival of the fittest. ^^ Whether man possesses the spontaneous power
called '*free will " or not, the work of supplying inducements for
good conduct is most useful to society. But religion, as generally
understood, pre-supposes free will ; and the definition of the word
responsibility implies its existence. The question as to the pres-
ence of such a faculty is an interesting one, and will now be briefly
considered.

The well-known doctrine of necessity leaves no j^lace for free
will. All acts are the consequences of motives, and are the out-
come of a balancing of interests. The heaviest side of the account
determines action. Our physical necessities supply the motives
for most of our activities ; our pursuit of food and clothing is of
necessity, and no condition is free from it. Evolution supports
and explains this doctrine, as can readily be perceived. It de-

EEVIEW OF THE MODERN DOCTRINE OF EVOLUTION. 239

rives our instincts from an ancestry whose daily occupation has
been their gratification. But it has been shown above that this
development does not supply the motives of an independent
morality. *

The direction of action under stimulus is determined by intel-
ligence, which is, as has been above maintained, the product of
experience. Intelligence is organized or classified knowledge, and
directs the activities set on foot by the likes and dislikes, that is,
the affections. When there is knowledge, there is no necessity for
spontaneous action or free will, since action is determined by the
organization of the mind. Even if the mind is conscious of insuf-
ficient knowledge, an inducement to seek knowledge is supplied,
and according to the result of investigation will be the direction
of knowledge.

But we are here brought to face the case where knowledge can
not be or is not obtained. This is the condition of the two ques-
tions of the practice of morals, and the nature of the future life.
The evolution of mind consists of a continual advance from the
known into the unknown, and a transfer of the unknown to the
known. So long as there is any inducement to progress of this
kind, and nature responds to inquiry, development will go on. Al-
though it is true that it is only among men, and but few men at
that, that the pursuit of knowledge is an occupation, most men
add to their stock incidentally as they pursue other avocations.
The knowledge of right and the inducements to its practice are
learned in their every-day intercourse, so far as it can be acquired.
But knowledge in these directions soon attains its limit, and ac-
cordingly, development dependent on knowledge must cease. If
any further progress in practical morals is to be made, some new
force must intervene at this point.

Here is the opportunity for the appearance of will or sponta-
neity ; here it is at least needed. I am willing to believe that it
may appear at this point, and that so long as we have to face the
unknown in moral progress, so long it will remain. As a force
it must be equivalent of other forces, but as a form of conscious-
ness it is a new element of mind. As represented in new molecu-
lar organization, it may always continue, even after much of the
unknown may have been conquered, and a stationary period may
have ensued. Such an accession to character would be a fitting

* " On the Origin of the Will." " Penn Monthly," ISVY.

240 GENERAL EVOLUTION.

crown of eyolution, and a justification of this labor of the ages.
If a true factor in human development, it might be compared, in
the creation of character, to the apical bud of a growing tree. As
the part pre-eminently living, it leads the growth of the trunk and
branches. They all follow of necessity the path it has marked out.
Under its lead they are successively formed, become fixed, and
finally decay.

PART II.

THE STEUOTUEAL EYIDEI^^CE OF

EYOLUTIO]^.

VII.

ON THE HOMOLOGIES AND ORIGIN OF THE TYPES
OF MOLAR TEETH OF THE MAMMALIA EDUCA-
BILIA.

I. THE TYPES OF MAMMALIAN MOLARS.

It has been already stated * that the transition from simple to
complex teeth is accomplished by repetition of the type of the
former in different directions. ^^In the cetaceans this occurs in
the Squalodonts ; the cylindric incisors are followed by flattened
ones, then by others grooved in the fang, and then by two-rooted,
but never by double-crowned teeth. This is the result of antero-
posterior repetitive acceleration of the simple cylindric dental type
of the ordinary toothed cetacean. Another mode of dental com-
plication is by lateral repetition. Thus the internal heel of the
superior sectorial tooth of a carnivore is supported by a fang
alongside of the usual posterior support of a premolar, and is the
result of a repetitive effort of growth-force in a transverse direc-
tion. More complex teeth, as the tubercular molars, merely ex-
hibit an additional lateral repetition, and sometimes additional
longitudinal ones. As is well known, the four tubercles of the
human molar commence as similar separated knobs on the [primi-
tive] dental papilla."

Accordingly, the simple tubercle may be regarded as the least
specialized form of tooth. It may be low and obtuse, as in the
Cliiromys, or the walrus ; more elevated and conic, as in the dol-

* " Method of Creation," p. 10. Philadelphia, 1871.
16

242 THE STRUCTURAL EVIDEN'CE OF EVOLUTION.

phins ; or truncate, as in sloths and some rodents. The form is
complicated in two ways, viz., either by the folding of the sides,
as in Glyptodon and many rodents, as Arvicola, Castor, Lepus,
etc. ; or by the develoj^ment of tubercles on the crown, as in Mus,
Dicotyles, Homo, etc. Upon this basis are constructed the more
complex types of teeth exhibited by the various families of Ungu-
lata and some Rodentia, as has been pointed out in the following
language : '^ The genus Uintatlierium^ has been shown to be a Pro-
boscidian, which combines some important features of the Peris-
sodadyla with those of its own order. . . . The number of such
characters was shown to be somewhat increased in Bathmodon,
which therefore stands still nearer to the common point of de-
parture of the two orders. This point is to be found in types still
nearer the clawed orders {Unguiculata) in the number of their
digits (4, 5), and in which the transverse and longitudinal crests
of the molar teeth are broken up into tubercles more or less con-
nected, either type of dentition [i. e., Proboscidian or Perissodac-
tyle] being derived according as such tubercles are expanded in
the transverse or longitudinal directions." f

As is well known, the crowns of the superior molar teeth of
the higher Mammalia are supported on three roots, two of which
are external, and the third internal. The corresponding inferior
molars are supported on two roots, and are therefore, in so far, less
complex. But these two roots usually support four tubercles, two
to each, while the roots of the superior molars support directly
but one each. Hence, as Prof. Harrison Allen remarks, the
crown of the inferior molar is more complex than that of the su-
perior. \

In tracing the degrees of complication of the crowns of the
superior molars of Mammalia from the simple cone of the Ceta-
cean, the first step is seen in the Squalodon and teeth of similar
character. In these there are two roots, antero-posteriorly related.
In the Squalodont Portheodon gervaisii {Squalodon Auct.) the
third root is present. In Mammalia with but three tubercles in
the crown, e. g., Carnivora, the inner root has much the form of
one of the external ones. In many of those with four tubercles
of the crown, e. g., Qiiadrumana, the form of the internal root is

* Eohasileus in the original. (Ed. 1886.)

f " On tlie Primitive Types of Mammalia Educabilia," published by E. D. Cope,
May 6, 1873. "Proceedings of the American Philosophical Society," 1873, p. 224.
X "Dental Cosmos," December, 1874.

MOLAK TEETH OF THE MAMMALIA EDUOABILIA. 243

not modified ; but in the Lophodont types it is materially altered.
In Hyracodon, RMnocerus, Anchitherium, Oreodon, Cervus, and
others, it is flattened, with the long diameter anteroposterior, and
is grooved on the inner face, so as to assume the form, as it does
the function, of two roots conjoined. In the temporary dentition
of Bus, Merychyus, etc., the inner root is divided, so that the
superior molar has four distinct roots.

The proper homologizing of the various forms of dental struct-
ure of the Ungulates with each other, and with the primitive
types of tubercular teeth, is entirely essential to their intelligent
classification, and therefore comprehension of their mode of origin.
In order to lay a foundation for this work, I define the four types
as follows, giving the subdivisions of the first two in brief, and
discussing those of the third and fourth more fully afterward :
Division I. Haplodont type ; the crown undivided or simple.
a. Crown low, obtuse; Cetacea {Be-
luga), Carnivora (Rosmarus).
h. Crown elevated, acute ; Cetacea
{Delplii7ius) ; canine teeth in
general.
c. Crown truncate ; Edentata {Bra-
dy pits) ; Rodentia { Qeomys,
Dipodomys).
Division 11. Ptycliodont type ; the crown folded on the sides ;
the folds frequently crossing the crown.
a. Sides only folded ; Rodentia
(Arvicola Castor) ; Edentata
^ {Glyptodon).
h. Summit of crown also folded ;
Rodentia {Lepus, Chinchilla).
Division III. Bunodont type ; crown supporting tubercles.
a. Tubercles few, opposite ; TJ71-
gulata, Achcenodon, Dicotyles,
Elotherium ; Carnivora, Pro-
cyon ; Rodentia, Heliscomys.
h. Tubercles few, alternate ; Hyop-

-, Fio. 17. — LeptocJicerus.

sodus.
c. Tubercles numerous, irregular ; Mastodon, Phacochoerus.
Division IV. Lophodont type ; the summit of the crowns
thrown into folds of transverse or longitudinal direction. Higher
Ungulates.

Fig. 15. — Glohicephalus.

Fig. 16. — Jaculus hudsonicus.

244 THE STRUCTURAL EVIDENCE OF EVOLUTION.

This division embraces the many types observed in the Ungu-
lates, some Rodents, and possibly Garni vora. Inasmuch as the
teeth of the maxillary and dentary (mandibular) bones do not al-
ways conform to the same type (e. g., Symborodo7i, Equus), it
will be necessary to consider them separately. Besides the differ-
ence in type, they differ in their rela-
tive development in width in the
more specialized forms ; thus, in
Homo, Mus, Mastodon, and such
genera, the molars of both jaws are
identical ; in Palceotlierium, Eohasi-
leus, Tcqnrus, etc., and most Car-
nivora, the superior are the wider,
the inferior narrower, appropriately
to the greater slenderness of the
mandibular bone. The latter, or
anisognathous type, may then be regarded as the more specialized.
The Bunodonts, except some Carnivora, are all of the former or
isognathous type ; among Lophodonts the few Rodents, the Dino-
theriidcB, and Elephas are isognathous, while all of the other
Prohoseidia, the Perissodactyla, and Rumina7itia are anisogna-
thous. Examples may be selected as follows :

Isognatlious ; Bunodonts : Homo, Dicotyles, Sus, Mastodon,
Elotlieriiim ; Lophodonts : Dmotheriidce, Eleplias ; Rodentia,
JSciuridce.

Anisognatlious ; Bunodonts : Macacus, Lemur oidea, Procyon ;
Lophodonts : A7iopIotherium, Hyoj^otamus, Oreodon, Ruminantia,
Perissodactyla, Batlimodon, TJintatlierium,

Fig. 18. — BJiinocerus (temporary).

II. THE subordi:n"ate types of bui^odojs^ts.

1. The Maxillary Teetli.^ »

It is apparent that the type of superior molar tooth which pre-
dominated during the Puerco epoch was triangular or tritubercu-
lar ; that is, with two external and one internal tubercles, f Thus,
of sixty-seven species of placental Mammalia of which the suj^erior
molars are known, all but four have three tubercles of the crown,

* This division is inserted from the " Proceedings of the American Philosophical
Society," for December, 1883, for the sake of supplying an omission in the original
memoir. (Ed. 1886.)

f See "American Naturalist," April, 1883, p. 407.

MOLAR TEETH OF THE MAMMALIA EDUOABILIA. 245

and of the remaining sixty-five, all are triangular, excepting those
of three species of Periptychus, and three of Oonoryctes, which
have a small supplementary lobe on each side of the median prin-
cipal inner tubercle.

This fact is important as indicating the mode of development
of the various types of superior molar teeth, on which we have not
heretofore had clear light. In the first place, this type of molar
exists to-day only in the insectivorous and carnivorous Marsupi-
alia ; in the Creodonta, and the tubercular molars of such Carnivo-
ra as possess them (excepting the i^lantigrades). In the Ungu-
lates its persistence is to be found in the molars of the Corypho-
dontidse of the AYasatch, and Dinocerata of the Bridger Eocenes.
In later epochs it is occasionally seen only in the last superior
molar.

It is also evident that the quadritubercular molar is derived
from the tritubercular by the addition of a lobe of the inner part
of a cingulum of the posterior base of the crown. Transitional
states are seen in some of the Periptychidae {Anisonchus), and in
the sectorials of the Procyonidae.

2. The Mandibular Teeth.

The tritubercular or triangular superior molar is associated
with a corresponding form of the anterior part of the inferior
molar. This kind of inferior molar I have called the tubercular
sectorial, and is very variable as to the degree of development of
the sectorial cutting edge. The anterior triangle is formed by the
connection by angle or crest, of the median and anterior internal
crests with the anterior external. Its primitive form is seen in
Didelphys, Pelycodus, Pantolambda and the Amblypoda gener-
ally ; in Centetes and Talpa ; and in its sectorial form, in Stypo-
lophus and Oxyaena, etc.

The * tubercular molar of some ViverridcB, and among the ex-
tinct forms especially the Didymictis protenus, Cope, present a
similar structure to that just described. This furnishes a ready
explanation of the tooth immediately in advance, which is the
primitive form of sectorial tooth characteristic of primitive Car-
nivora. The three anterior tubercles are largely developed, stand-

* The remainder of this section (2) is taken from the writer's " Synopsis of the
Vertebrata of the Eocene of New Mexico," p. 800. Publication of the U. S. G. G.
Survey, W. 100th Meridian, 1875. (Ed. 1886.)

246 THE STRUCTUKAL EVIDENCE OF EVOLUTION.

ing at opposite angles of a triangular space ; the outer and ante-
rior cusps are the most elevated, and the ridge which connects
them is now a cutting blade. The posterior portion of the tooth
does not share in this elevation, and its two tubercles are in some
genera obsolete, and in others replaced by an elevation of one mar-
gin, which leans obliquely toward the middle of the crown. In
Mesonyx this is represented by a median longitudinal crest. If
the two tubercles of the posterior part oi this tooth (which may be
termed a tubercular seciorial) are elevated and acute, we have the
molar of many recent and extinct Insectivora ; if the same por-
tion (now called a lieel) is much reduced, we have the type of
Oxycena and Stypolo2)lius. In the Canidce the three anterior tu-
bercles are much less elevated than in the genera above named ; the
external is much the larger, and the anterior removed farther for-
ward so as to give the blade a greater antero-posterior extent.
The heel is large and without prominent tubercles. In the Muste-
lidm the inner of the two median cusps is often reduced to a rudi-
ment, or is entirely wanting, and the heel is large. The lower
sectorial of the HycenidcB has no inner tubercle, and the heel is
much reduced. In some of the saber-toothed tigers the heel re-
mains as a mere rudiment, while in the true cats it has entirely
disappeared, and the carnassial tooth remains perfected by sub-
traction of parts, as a blade connecting two subequal cusps. The
HycBnodontidcB, as is known, possess three carnassial teeth without
inner tubercles. The history of this form is as yet uncertain, as
it was evidently not derived from contemporary forms of the
Eocene with tubercular sectorials.

The development of the inferior carnassial dentition has thus
been accomplished by the subtraction of the inner and posterior
cusps, so that of the original four of the quinquetuberculate molar
but a single one, i. e., the anterior external, remains.

III. THE SUBORDIjq-ATE TYPES OF LOPHODOXTS.

1. The Maxillary Teeth,

In the essay already quoted * the following remarks (page 7)
explain the relation between the Bunodont genera and several of
the Lophodont types of superior molar teeth : "In the superior

* "Primitive Types of Mammalia Educabilia," May, 1873, and Hayden's "Re-
port on Geological Survey of Montana, Wyoming, etc.," ISYS, p. 646.

MOLAR TEETH OF THE MAMMALIA EDUCABILIA. 247

molar series the flattening of the outer tubercles may proceed so
far as to produce, on wearing, a confluence of the [resulting] cres-
centoid surfaces. ... In both PalcBOsyops and Hyrachyus these
tubercles of the upper molars are confluent into two Vs (more or
less open when unworn). In the former the inner tubercles retain
their primitive conic tubercular form, but in Palceotheriwn, EJii-
nocerus, Lopliiodon^ Hyrachyus, and Tapirus they elongate trans-
versely so as to meet the corresponding outer tubercles (now crests)
forming the familiar cross-crests of those genera. If alternate,
the oblique crests of Palceotheriuyn ; if opposite, the cross-crests
of Tapirus. If, on the other hand, the inner tubercles flatten like
the outer, we have, on wearing, the quadricrescentoid [Selenodont]
type of the Ruminantia and Anoplotlierium: In the Quadruma-
nous families, including man, the primitive quadrituberculate type
of molars is preserved."

Four types of Lophodont dentition are included in the above
discussion, and three others may be added. They belong to two
series, viz., those in which the crests represent the modification
of opposite tubercles, and those where the tubercular elements of
the crown are alternate. These series may be called the Ammho-
dont (alternate), and Antiodont (opposite), and the component
types are :

Antiodoj5"ts. — Selenodont (Ruminants) ; Tapir odont {Tapir,
Rhinoceriis) ; Trichecliodont (Manati, Elephant).

Amcebodokts. — PalcBotheriodont (Palasotherium, etc.) ; Sym-
lorodont (Palaeosyops Symborodon, etc.) ; Batlimodont (Bathmo-
don, etc.) ; Loxolopliodont (Uintatherium, etc.).

These types are defined as follows :

1. Antiodoxts.

Sele7iodonts.—T\\Q tubercles separate or united at their angles,
much elevated, narrow crescentic in section, separated by deep
valleys.

To this group belong the molars of the Euminants, the Tra-
gulidce, the Oreodontidm, and Mery copotamido ; of Perissodac-
tyles the EquidcB.

Tapir odo7its.— The outer tubercles longitudinally compressed,
subcrescentic in section ; the inner transversely compressed, con-
tinued as transverse ridges to the end or middle of the correspond-
ing exterior crests.

RUnocerus, Tapirus, Hyrachyus, LopUodon, and Hyrax rep-

248 THE STRUCTURAL EVIDENCE OF EYOLUTIOX.

resent this type ; the last molar of LopModon appears to be Attkb-
lodont,

Tricliecliodonts. — Tubercles confluent into two or more trans-
verse crests.

The Dinotherium represents this form, so does Eleplias, Tri-
checus (the manati), and a number of the larger Marsupialia.

2. Amcebodonts.

PalcBotheriodonts. — External tubercles longitudinal, subcres-
centic in section ; the inner united with them by transverse oblique
crests.

Palceotherium and Ancliitlierium present this type, which only
differs from the Tapirodont in the alternation of the opposing
tubercles.

Syniborodonts. — External tubercles longitudinally compressed
and subcrescentic in section ; the inner indejDendeut and unal-
tered, i. e., conic.

To this group are to be referred the types of Palcsosyops, Me-
nodus, and Symhorodon. They, of all Lopliodonts, approach near-
est to the Bunodonts,

Bathmodonts. — The posterior pair of tubercles approximated
and connected, together compressed and subcrescentoid in section ;
the anterior outer connected with the anterior inner by an oblique
crest forming a V with the preceding.

Bathmodon and Metalopliodon. — The homologies of the crests
are difficult to make out ; the subcrescentic crest of the second
molar may include only the posterior outer tubercle, and thus be
entirely homologous with the posterior crescent of Palseosyops. In
support of this view we have the structure of the premolars, where
it becomes the only external crescent, while the anterior transverse
crest turns round on its inner side, supporting the inner anterior
tubercle of the tooth. [Note to this edition : The latter view is
the correct one, as the posterior inner tubercle is wanting.]

Loxolopliodonts — Anterior inner tubercle connected with the
two external by oblique crests ; the posterior inner tubercle rudi-
mental or wanting.

Uintatherium and probably Tillotherium represent this group,
both being like those of the last, extinct genera from the Eocene
of Wyoming.

MOLAR TEETH OF THE MAMMALIA EDUCABILIA. 249

• 2. Tlie Mandibular Teeth,

The types of structure are less numerous than those of the
maxillary teeth, since I am only acquainted with six. Still more
distinctly than those of the upper jaw do they represent the types
of opposite or alternating tubercles, or the antiodont and amoebo-
dont. The essential principles of modification are the same as in
the maxillaries, and they correspond with them as to genera, as
follows :

Aktiodont.

Inferior.

Selenodont.
Hyracodont.

Trichecodont.

Superior.

Selenodont.

Tapirodont pt.
j Tapirodont pt.
( Trichecodont.

Amcebodoxt.

J Palaeotheriodont.

■ I Symborodont.

Selenodont pt.

j Bathmodont.

( Loxolophodont.

The characteristics of these groups are as follows :

A. Antiodonts.

Symborodont.

Hippodont.

Loxolophodont.

Selenodonts. — Constructed, typically, like the upper molars,
Rummantia.

Hyracodonts, — External tubercles compressed longitudinally
and crescentic in section, continuous by a cross-crest with the cor-
responding tubercle of the iuner side.

The animals which possess this type of teeth are the Bliinoce-
riiSj Hyracodon, and the Hyrax ; it is nearly approached by some
of the Hyrachyi. It corresponds in structure with the true tapiro-
dont arrangement of the maxillary teeth ; but many of the Ta^^iro-
donts have the Trichecodont type of mandibular teeth.

Trichecodonts. — Definition the same as for the maxillary teeth.

Tapirus, LopModo7i, Hyracliyus, Dinotlierium, Eleplias, Tri-
checus (the manati), and the Kangaroos and their extinct allies

belong here.

B. Amcebodonts.

Hippodonts. — In the horses the maxillary molars are con-
structed on an opposite crested basis, while the mandibulars repre-

250 THE STRUCTURAL EYIDEII^OE OF EVOLUTION".

sent an alternate crested type. This is not constituted as in the
next form, by a union of alternating tubercles, but as in the Sele-
nodonts by the special deyelo^Dment of each crest into a crescent
extended antero-posteriorly. As alternating, the inner crescents
stand at the apices of the outer, and are connected with them.
In Ancliitherium the inner are so reduced as to constitute a condi-
tion intermediate between the Hippodont and Syiiiborodont types.

Syniborodonts. — The alternating tubercles connecting by
oblique ridges which form together two Vs.

To this type is to be referred a great number of Perissodac-
tyles, e. g., Anchitheiium, Palceotherium, Falmosyops, Menodus,
Syiiiborodon, A ncMppodus.

Loxolopliodonts. — Alternate cusps connected by two cross
ridges from the outside forward and one from the inside forward ;
from which result an oblique posterior cross ridge, and a V open-
ing inward.

Here are Eohasileus and Batlimodon- ; the last molar of the
latter having the anterior ridge of the V quite low.

S. Comparison of the Opposing Series.

In review, the above types of molar dentition may be classified
as follows, with reference to the amount or complication of the
modification of the tubercular type. The orders of Ungulata with
which they correspond, are also given.

a. Both inner and outer tubercles crescentoid.

JRuminantia.
(Anoplotheintim, Oreodon, Hyopotamus).
Perissodactyla (Equidce).
13. External tubercles only crescentoid ; the inner transverse
or tubercular.
Tapirodonts. j

Palaeotheriodonts. >• Perissodactyla in gen.
Symborodonts. )

y. Neither kind of tubercles crescentoid, but. united in pairs.
Trichecodonts. Prohoscidia.

It may be added that the groups arranged under y are the
only ones in which the types of crests of the superior and inferior
molars are fundamentally simple and alike. Thus in the group
a, tubercles of both upper and lower series are modified indeiDcnd-
ently to produce the type ; in group (3, the tubercles of the upper
series are modified independently of each other, while those of the

MOLAR TEETH OF THE MAMMALIA EDUCABILIA. 251

inferior series unite, in order to produce the result ; in diyision
y the tubercles of both jaws unite entirely across the crown, with-
out any distinction between those of the outer and inner sides.
Thus the molar type of dentition of the Proboscidians is the most
generalized among the Lophodonts, resembling in this respect the
type of construction of the feet.

lY. THE ORIGIK OF THE MODER]S" TYPES OF BUKODOKT AKD

L0PH0D02iT DENTITIOi^.

The four types of molar dentition, the Haplodont, Ptycho-
dont, Bunodont, and Lophodont, are by no means sharply de-
fined, but pass into each other by insensible gradations at many
points. The addition of cusps to the simple cone has been
accomplished by the appearance of folds at the base of the
crown, which have increased in size so as to resemble the primi-
tive cusp to which they are attached. As already pointed out,
the first additional cusp in the transverse direction appears on the
inner side of the first, or anterior cusp. The last one was ap-
parently the inner posterior. I first consider the carnassial mo-
lars.

1. Tlie Carnassial Bunodo7its.

In tracing the appearance of the different types of superior
sectorial in time, the following facts are patent : In the Eo-
cene genera Mesonyx, AmUyctonus, Oxymna, Stypolophus,* etc.,
the inner tubercle is much more largely developed than in any ex-
isting Carnivora, with the exception of some of the Viverridce. In
all, the sectorial crowns are less efficient as shear-like cutters than
in Canidce, Mustelidce, Hycenidm, and Felidce, on account of the
shortness of the posterior blade and the slight compression of the
anterior cone. On the other hand, in all of them the number of
teeth presenting the carnassial or three-tubercled type is greater
than in existing genera, the posterior upper molars in the latter
being either narrowly tubercular or wanting. The genus Hyceno-
don, while agreeing with the others in this respect, differs from
them in the great reduction of the inner cusp, which is obsolete
even in the representative of the true carnassial tooth, although
the inner root remains in all. Hence this type of dentition might
be regarded as the most specialized of those of the Carnivora,

* In the original, the synonym Prototomus is used here.

252 THE STRUCTURAL EVIDENCE OF EVOLUTION.

but for the fact of the imperfection of the shear blades in all ex-
cept the last. This is seen in the large and prominent anterior
cusp and very short posterior blade.

In all recent and most Miocene Carnivora, the sectorials are
reduced to one in each jaw, the exception in the latter period
being the genus Hycenodon, which did not continue later. The
posterior carnassials of the Eocene forms disappear, and in the
most specialized recent families HymnidcB^ Mustelidm, and Fe-
lidcB have scarcely any representatives. The shortening of the
series appears in the premolars as well, until we have the formula
of the FelidcB, P. m. 2 ; M. 2.

In the inferior dentition the same process may be observed in
the successional modifications of the entire series. The Eocene
forms of carnivora frequently display more numerous sectorial
teeth (such as they are) than any of the existing families. The
important change, which is clearly indicated, is the progressive
extinction of the genera with numerous sectorial teeth, accom-
panying the increasing specialization of the sectorial tooth in the
genera which remain. In other words, the numerous types of
digitigrade carnivora which have survived are those developing
but one sectorial tooth (whose earliest rei^resentative is Didymic-
Us). The increased perfection of the sectorial tooth has been as-
sociated with a reduction in the number of other molars, first,
posterior, then anterior to it, which reduction has been accom-
panied by an increased relative size of the sectorial. By this pro-
cess concentration of the carnassial function has been gained, and
increased robustness of the jaws, by progressive shortening. The
slender form of the rami of the Eocene genera and Hymnodon are
much less efficient in functional use than the stout jaws of exist-
ing MustelidcB, Hywnidce, and Felidce.

2. The Lopliodonts.

Transitions between the Bunodonts and Lopliodonts are very
obvious, so much so as to lead to the belief that the several sub-
divisions of the Lopliodonts represent modifications of correspond-
ing types of Bunodonts, and that the two are partially '^ homolo-
gous groups." Both present corresponding Amoebodont and An-
tiodont types ; as an example of the former kind of Bunodont,
the mandibular molars of the genus Hyopsodus may be cited ; of
the latter kind, the same of the genus AchcBnodon, both the ear-
liest, or Eocene genera. It remains to indicate the intermediate

MOLAE TEETH OF THE MAMMALIA EDUCABILIA. 253

forms, if any there be, which give color to the supposition that
the various divisions of Lophodonts have descended from Buno-
dont predecessors. Here, then, I mention a fact of prime impor-
tance, i. e., that in America, at least, no Selenodonts are known
from formations of older age than Miocene ; while the greatest
development of Bunodonts is in the beds of the next older epoch,
the Eocene.

The special forms of Lophodonts may be separately considered
as follows :

First, as to the opposite and alternate types, or the Antiodont
and Amoebodont. They pass into each other by many intermedi-
ate conditions among the Bunodonts, as in Notharchis, Lim-
notherium, etc., of the Wyoming Eocene. There is reason, also,
to believe that this has been the case with some of the Lophodonts
after they had left the bunodont stage behind. Thus Equus is an
antiodont as to its upper molars, but has been probably derived
from Palmotlieriodont ancestors, which are amoebodont ; this is
rendered especially probable by the fact that the mandibular teeth
are of the amoebodont division (hippodont). It is also highly
probable that the antiodont genus Tapirus, though so near to
PalcBotlierhim, was derived from an antiodont Bunodont. Hence,
while the discrimination between opposite and alternate types is in
some cases most radical, in others its importance is but slight.

L Antiodonts: Bunodont type AcTicenodon (Fig. 19).

1. Selenodont type apjDroximated by the bunodont Hippopota-
muSi where the tubercles are com^^ressed, thus : the intervening

Fig, 19. — AcTicenodon insolens.

valleys are deepened, and the cusps wear readily into separate
crescents. Another intermediate form is seen in the genus An-
tliracotherium, where the tubercles of the mandibular teeth are
compressed, while they remain conic (Fig. 21) ; selenodont forms
of Omnivora present us with near approaches to these Bunodont
genera. Thus in Hyopotamiis and Anoplotheriiim, the crowns.

254 THE STRUCTURAL EVIDENCE OF EYOLUTIOIT.

when unworn, present four principal tubercles, wliicli are openly
V-shaped in section, and which are separated by open valleys.

The latter are deeper than
those of the truly Btmo-
clont genera, but much
shallower than those of the
typical Selenodonts. In
Oreodon the valleys are
somewhat deepened and
the crescents elevated, while
in the deer the same infold-
ing is carried still further.
In the Cavicornia the type
reaches its fullest expres-
sion in the loss of the shoul-
der at the base of the crown,
the great elougation of the
latter, and corresponding-
ly deep infolding of the
terminal valleys.

Professor Lartet* states
that the most ancient deer
have very short - crowned
molars, and the depressions
on the surface are so shallow that the bottom is always visible,
while in the CervidcB of the more recent Tertiary periods, and

especially the Plistocene and living species,
these same cavities are so deep that what-

FiG. 20. — Hippopotamus.

Fig. 21. — Hyopotamus velaumis.

Fig. 22. — ITyopotamus americanus.

Fig. 23. — Procamelns robust us.

ever be the state of attrition, the bottom can not be seen. This,
he says, is a perfectly reliable rule for distinguishing the ancient
from the more modern forms of deer, and can be applied to other
animals as well as the CervidaB.

* u

Comptes Rendus," 1868, p. 1119.

MOLAR TEETH OF THE MAMMALIA EDUCABILIA. 255

Fig. 24. — Merychyus major.

The writer nearly contemporaneously * recalled the obserya-
tions of Leidy that the teeth of the Oreodont ^' Merycliyus are
more prismatic, have larger crowns atid shorter roots, approaching
the sheep, as Oreodon does the deer." Now Oreodon is Miocene,
and MerycJiyus Pliocene. It was then ob-
seryed : *' This phenomenon suggests an ex-
planation on the score of adajjtation which
the other cases do not. The existence dur-
ing the later period of a [hardjer material
of diet would increase the rapidity of wear-
ing of the crown of the tooth, and require a
longer crown and greater rapidity of j)rotru-
sion. This necessitates a diminution of the
basal shoulder and shortening of the roots, producing the prismatic
form aforesaid."

These observations render it highly probable that the seleno-
dont molar is produced by a modification of the antiodont buno-
dont molar. Also, that the manner of the change has been by
constant acceleration of growth of the folds of the tooth upward
and i^erhaps downward in its long axis ; and an acceleration in the
lengthening of the crown.

2. Tapir odonts. — This form is so nearly similar to the Palaeo-
theriodont that any series annectant between the latter and the
Bunodonts will render very probable such a connection for the
Tapirodonts also. Indeed, it is clear that the same evidence will

be sufficient in both cases, since the pre-
molars and last molar of Lopliiodon are
amoebodont, like Palceotherium. In point
of fact, however, the tubercles of the molars
of Achcenodon are partly united in transverse
pairs, while there are intermediate tubercles
connecting the opposite cones in some molars

of Elotlierium. These structures foreshadow this group as well

as the Trichechodont.

3. Trichecodonts. — The J[/«.«;^Of7o^5 and Elephants form a most
complete series between this form and the Bunodonts, as has been
pointed out by Falconer. In this series, the transverse rows or
pairs of tubercles, as well as the crests, may be few or many. Thus

Fig. 25. — Tapirus.

*" Proceedings of the Academy of Natural Sciences of Philadelphia," 1868,
p. 2Y4. " Origin of Genera," p. 44.

256 THE STRUCTURAL EVIDENCE OF EVOLUTION.

in Elotlierium, HalWierium, and Tricliechus they are few ; in
Trachytherium and Dinotlierium more numerous ; in Mastodon,

Stegodon, and Elephas, most
numerous. The tubercles are
united into serrated cross-
crests in Halitherium, the ex-
tinct sea-cow ; in Tracliytlie-
rium, another fossil ally of the
Manati, the tubercles are not
united. The succession from
Mastodon to Elephas may be
represented by the accompany-
ing figures : Fig. 26 (from
Cuvier) is a molar of M. an-

FiG. 26. — Mastodon angusHdens.

gustidens, where, beside the principal tubercles, numerous lesser
ones appear. Fig. 27 represents Mastodon oMoticus, in which

Fig. 27. — Mastodon oMoticus.

Fig. 28. — Dinotherium giganteum.

the opposite tubercles are nearly united into transverse crests.
In Dinotlierium (Fig. 28) and Elephas (Fig. 29) the union is
complete. The relation of these
genera has been described as
one of *' inexact parallelism" ; a
condition supposed by the writer
to de23end on modification in
descent under the law of acceler-
ation. The language used is :*
^* The young tooth of Elephas,
moreover, is represented by a

» . n T , TT 1 Fig, 29. — Elephas indicns.

series of independent parallel ^

laminee at first, which, when they unite, form a series of crests

* "Origin of Genera," p. 17.

MOLAR TEETH OF THE MAMMALIA EDUCABILIA. 257

similar to the type [i. e., pattern] of the genus Mastodon [Stego-
don\ and others of the beginning of the series. The deposit of
cementum takes place later, till the valleys are entirely filled
up. Thus the relations of this
part of the tooth structure in
the series are also those of the
cuccessional growth of Elephas
or the extreme of the series."
The transition from the

Fig. 30. — Microsyops elegans.

bunodont type to the lophodont in the mandibular dentition is
seen in the Eocene genera Microsyops and Limnotlierium, where
the opposite cones are connected by a low cross-crest.

n. Amcebodonts; Bunodont type ^^o/^.so(iws.*

4. Symlorodonts. — In Hyopsodus the exterior cones are already
somewhat excavated on the inner side, so that a section of each is
somewhat triangular. It is obvious that but little more compres-
sion and curvature are required to produce the type of FalceosyopSf

Fia. 31. — Eyopsodus.

Fig. 33. — AncMppodus.

Fig. 32. — PalcEOsyops IcEvidens.

Fig. 34. — Palceosyops.

etc. (Fig. 32). The angles of the outer cones in Hyopsodus are
also slightly produced as low ridges to the bases of the alternating
tubercles of the opposite side : the elevation of these ridges is only

* I oridnallv (" On the Priinitive Types of Mammalia Educabilia," p. 9 ; " Hay-
den's Geolog. Survey Terr.," 1872, 1873, p. 648) selected Pliolophus ( Oligotomus Cope)
for this position, but as it has a considerable diastema, it is better exchanged for
Hyopsodus^ where the dental series is uninterrupted.
17

258 THE STRUCTURAL EVIDENCE OF EVOLUTION.

iiG. 35. — Falcjcotherlum.

Fig. 36. — HipposTjus.

necessary to produce the two Vs of the mandibular dentition of
PcdcBotherium, Palceosyops (Fig. 34), Symiorodon, Anchippodus
(Fig. 33), and all their allies (Fig. 35, PalcB other ium).

5. PcdcBotlieriodont type.— Immediately following the form of
the Pcdceosyojjs molar we have that of Hipposyus, where inter-
mediate tubercles stand be-
tween the inner subconic and
the exterior longitudinal cres-
centoid tubercles. They are
compressed so as to be trans-
verse, and only need more
complete connection with the
adjacent tubercles to give the
oblique transverse ridges of
A ncliitheriiwi, Palceotherium,
and Hyracodon, Rlmiocerus,
etc. Hipposyus was origin-
ally compared with Anchitherium by Dr. Leidy, and the writer in
ignorance of his language remarked :* "An interesting annectant
form is seen in Lamhdotherium\ procyoiiinum, where the two inter-
mediate tubercles which separate the inner cones from the outer
Vs in Limnohyus are so developed as to constitute parts of an in-
complete pair of transverse
ridges wiiich disappear in
front of the bases of the
outer Vs. They represent
the oblique crests of Pcdmo-
therium and A^ichitherium,
and thus the genus Lamb-
dothermm furnishes a sta-
tion on the line from Palce-
osyops to the horses." Contemporaneously and quite independ-
ently Prof. Marsh expressed similar views X as to its affinities.

A greater longitudinal extent of these ridges or longitudinal
expansion of the tubercles in the molars in both jaws, the oblique
connections being still retained, gives the type of Equus (Fig. 39).
The elevation of the tubercles and deepening of the valleys gives

* Hayden's "Geol. Surv. Montana," etc., 1873, p. 647.

f This species was in the original erroneously called Orohippus procyonirvus,
(Ed. 1886.)

X "Amer. Joum. Sci. A>ts," 1873, p. 407.

Fig. 37. — Hipposyus. Fig. 38. — Ihjpoliippus.

Fig. 39.

MOLAR TEETH OF THE MAMMALIA EDUOABILIA. 259

us the Selenodont type of superior molars again in this genus •
while the lower molars only differ from that type in haying the
crescents alternate instead of opposite, forming the Hippodont
pattern (Fig. 40). There can be little doubt that the line of the
horses comes through Hipp osij us* from the Bunodonts, rather than
through Palceotherium, as has been sug-
gested by some writers.

6. Bathmoclont type. — I know of no ge-
nus which by its intermediate structure
connects this type of molar with the Amoe-
bodont form of Bunodonts.f Such will
doubtless be discovered, for it is impossible
that the upper molar of Bathmodon could
have been produced by the modification of
any known PalsGotheriodont, the type which
it most nearly resembles. The structure of
the feet of the animal forbids any such sup-
position. Such intermediate tyj^es would
have, firstly, the (oblique) crests more nearly
equal in length and similar in direction. A
depression of the crests and indication of
diagonal ridges connecting the tubercles in
the opposite direction would produce an
approach to a W, and the form of Hyopso-
dus. That this was probably the history
of this curious type is rendered probable by
the form of the mandibular teeth, which exhibit two of the in-
termediate stages above anticipated. Thus the last inferior molar
exhibits two obliquely transverse crests of subequal length, with
rudimental oblique or diagonal ridges connecting them. In the
median lower molai's one of the latter is developed, giving a V,
as in PalcBotherium, but the posterior one is undeveloped, leaving
only the original oblique cross- crest. J

7. The Loxolophodonts. — Like the preceding group I know
of no type connecting this form with the Bunodont, but antici-
pate the discovery of a type with, a rudimental posterior V on the

Superior molar of
Equus,

Fig. 40. — Inferior molar of

Equus.

* I have since shown that Hyracotherium and Pliolophus, which have very
similar dentition, are the types which occupy this position. (Ed. 1886.)

•f Such has since been discovered in the genus Pantolambda (Cope). (Ed. 1886).

X See " Proceed. Amer. Philosophical Society," Sept., 1872, " On the Dentition of
Metalophodony

260 THE STRUCTURAL EVIDENCE OF EVOLUTION.

upper molars,* which shall connect it with the W-shaped type
proposed above as the probable predecessor of Bathmodon. Or, a
pair of oblique parallel crests with rudimental diagonals like the
posterior lower molars of Bathmodon may intervene between this
form and the Bunodont. This is, however, not probable in view

Fig. 41. — Bathmodon.

of the diagonal crest of the upper molars (Fig. 42, Uintatlierium
robustum), and especially if the parallel with the type of the
lower molars is kept up. These are like those of Bathmodon, ex-

Figs. 42 and 43. — Uintatherium rohustum.

cept that the type of the middle molars of the latter is continued
to the posterior end of the series in Uintatherium (Fig. 43) ; that
is, the last molar of the latter consists of a V and an oblique cross-
crest.

Y. RELATIOKS OF THE TYPES OF DEI^TITIOI^' TO TYPES OF FOOT

STEUCTURE .

I hope that I have succeeded in showing that the Bunodont
and Lophodont types of dentition form two homologous series,

* This has since been discovered in Pantolambda (Cope). (Ed. 1886.)

MOLAR TEETH OF THE MAMMALIA EDUCABILIA. 261

similar to those already indicated among BatracMa, Anura, CepJi-
alopoda, etc.* That this relation indicates descent of the corre-
sponding terms of the one series from those of the other has also
been rendered highly probable. This conclusion has also been
previously stated as a theorem, f as follows : ^' V* The heterologous
terms or genera in the later series are modified descendants of those
of the earlier series " ; in other words, that certain groups higher
than genera are produced from others of a similar high value by
*^ descent with modification."

As already pointed out, the Bunodont primary genera belong to
the older geologic epoch of the Eocene, while most of the deriva-
tive ones belong to later periods. Some were contemporary with
the primary forms, but doubtless have descended from pre-existent
members of the same type as yet unknown to us. The genus
Achmnoclon, Cope, is especially generalized in three respects : (1)
the simplicity of the construction of its molars ; (2) the same
simplicity of the premolars, which are without inner or posterior
lobes ; (8) the absence of all diastemata and consequent continu-
ity of the dental series. Hence it maybe regarded as more primi-
tive than PalcBOchcerus, Cheer omor us, Dicotyles, or Elotlierium,
in all which there are marked diastemata. The two series may then
be arranged as follows : with the understanding that in some cases
names of genera used represent rather family groups, in which
the special generic lines have not yet been made out.|

The following table has been already published in its essential
features in the ^* Report on Geological Survey of the Territories,"
1873, p. 648.*

It remains now to ascertain whether the genealogical or taxo-
nomic relations expressed by the teeth coincide with those derived
from the other diagnostic regions of the body. First of these must
be selected, as of chief importance, the limbs and feet.

* See " Origin of Genera," p. 53. t Lo<^- ^«^- P- '^9.

X Since the following table was published it has become probable that Achaeno-
don is an unguiculate and a flesh-eater. It has also been discovered that the genus
Phenacodus possesses the characters which give it the place as the ancestor of all
the lines in the table. (Ed. 1886.)

# It was previously published in a separate form in " On the Primitive Types of
Mammalia Educabilia," May 6, 1SY3. An error occurs in this edition in the reversal
by a lapsus calami of the positions of the types Omnivora and Anoplothcrium. It
is also important to note, that in the " Report G. S.," p. 645, where it is stated that
" during the Eocene they (the orders) were in process of difPerentiation," etc., Mam-
malia Educabilia and not Zissencephala, are referred to.

262 THE STRUCTURAL EVIDENCE OF EVOLUTION.

r^_

13:1

52:
O

Q
O

•to

Loxolophodont

Bathmodont

o —

o -

Symborodont
Palseotheriodont
Selenodont pt.

-8

_ P _

■5.

OS
O

_ o

Trichechodont

8
•50

- o -

I-

Tapirodont

— % — h — -o Selenodont

-Y-

MOLAR TEETH OF THE MAMMALIA EDUCABILIA. 263

We may look on the Artiodadyla — even-toed or cloven- footed
mammals — as one of the most homogeneous groups in the class,
not only in respect to the structure of the extremities, but also in
that of the cranium, vertebrae, etc. But here we have both Buno-
dont and Selenodont types of molars. The Perissodactyla, as de-
fined by the feet, axis, palate, etc., present us with the Symhoro-
dont, PcdcBotheriodont, Tapirodont, and Selenodont types of denti-
tion in the superior series, and the Hippodont, Hyracodont, Pa-
IcBotheriodont, and Trichecliodont types in the mandibular teeth.
The pentadactyle, plantigrade type, for which I have used the
name Proboscidia, presents us with the Trichecliodont, Bathmo-
dont, and Loxolophodont types of molar structure. Among Siren-
ians, as defined by the marked peculiarities of the entire skeleton,
we have the great differences in dentition presented by Halicore
and Trichecus, the former being Haplodont, the other TrichecJio-
dont. Finally, the Marsupial group is unquestionably well defined,
and here Pliascolomys is Ptycliodont ; Didelphys, Bunodont j Pe-
taiirus between Bunodont and Selenodont, and the Kangaroos and
their gigantic extinct allies the Diprotodontidce, Trichecliodont.

It is thus evident that the molar types are everywhere subor-
dinated to those which we call ordinal ; therefore in the case of
the placental mammals, and especially those with complex folding
of the cerebral hemispheres, to the types of construction of the
feet. As to the modifications presented by the canine and incisor
teeth, these exist within a still more narrow range of variation ;
for instance, in the allied genera Equus, Rhinaster, and Symhoro-
don ; Sus and Phacochwrus ; Bathmodon and Unitatherium, and
others.

It is thus probable that modifications in the three points of
structure considered were introduced in the following order :

First, Of the feet.

Second, Of molar type.*

Third, of the relations of canines and incisors.

With regard to the significance of the tnree types of feet, Pro-
hoscidian, Perissodactyle, and Artiodactyle, it has been already
remarked: ^'It is to be observed that the lines of Ungulata,

* In the case of the Marsupialia the relation of the dental and extremital types
may be reversed. Thus we have pentadactyle plantigrade forms (Opossums) and
(nearly) didactyle digitigrade forms {Macropus) in the same order. Also Hahnatu-
rus and Diprotodon, both Trichechodonts, differ in the type of feet, as do the car-
nivorous Didelphys and Thylacinus, both Bunodonts.

264 THE STRUCTUEAL EVIDENCE OF EVOLUTION.

Quadrumana, and Carnivora originate in plantigrade types, a
state of things quite predominant among the lower series or Lis-
sencephala (smooth brains). It is universal in Edentata and very
usual in Rode7itia and Insectivora. The lower forms of Marsu-
pialia and all of the Monotremes present it. In the Marsupials,
Rodents, Ungulates, and Carnivores, we have series whose highest
expression is in the most highly digitigrade genera."* To this it
may be added that the lower terrestrial vertebrates are plantigrade,
with some exceptions. Thus in some Anurous BatracMa there is
a partial digitigradism ; the only digitigrade Reptilia are some
Dinosauria, especially such carnivorous forms as Lcelaps ; all
birds are digitigrade. The digitigrade modification evidently has
reference to speed in running, or projectile force in leaping.

The connecting points between the different types of foot-
structure among the Ma7nmalia Educahilia are as obvious as in
the case of the types of molar structure. Examples may be ad-
duced as follows :

Carnivora. — In all of the genera of the Eocene Carnivora which
I have had the opportunity of examining, excepting 3Iesonyx,
namely, Amhlyctonus, Oxycena, Prototomus, Didymictis, the tibio-
astragalar articulation is of a primitive character. The astragalus
is flat, and the applied surfaces are nearly a plane, and without
the pulley-shaped character seen in existing Carnivora ; as dogs,
cats, and in a less degree in the bears and in other Mammalia with
specialized extremities, as Perissodactyla, Artiodactyla, etc. The
simplicity of structure resembles, on the other hand, that found
in the opossum and various Insectivora, Rodentia, and Quadru-
mana, and in the Proioscidia, most of which have the generalized
type of feet. The structure indicates that the carnivorous genera
named were plantigrade — a conclusion which is in conformity
with the belief already expressed that the Mammalia of the Eocene
exhibit much less marked ordinal distinction than do those of the
Miocene or the recent periods. It is, indeed, questionable whether
some of the genera here included in the Carnivora are not gigantic
Insectivora, since the tibio-tarsal articulation in many, the separa-
tion of the scaphoid and lunar bones in Mesonyx, the form of the
molars, and the absence of incisor teeth in some, are all character-
istic of the latter rather than the former order.

Artiodactyla. — Approximations to the Perissodactyla are to be

*" Mammalia Educabilia," p. 8; Hayden's "Geological Survey," 18Y3, p. 647.

MOLAR TEETH OF THE MAMMALIA EDUOABILIA. 265

seen in Hippopotamus in the increase in development of the lat-
eral or first and fourth digits, thus equaling the number in the
fore-foot of Tapirus and Menodus, though preserving the equal-
ity of the two median digits. But an inequality of these digits
appears in the genera Anoplotherium and Cmnotlierium, as has
been stated^ in the following language : '^In Anoplotherium se-
cundarium the digit ii is developed in each foot, though not
nearly so long as m, which is nearly symmetrical in itself. There
is an approach to the same structure in the manus of Cmnotlie-
rium.^^ The only approximation to the Proboscidian type is to be
seen in the shortening of the metapodial bones in Hiiopopotamus,
a point of very inconsiderable value.

Perissodadyla. — Approximation to the preceding order is
made in the anterior foot of Menodus, in which, according to
Marsh, there are four toes of nearly equal size, f Apj^roximation
to the Proboscidia X is seen in Symtorodon, where the cuboid facet
of the astragalus is rather larger than in Rhinoceros, and devel-
oped much as in Bathmodon ; the small third trochanter of the
femur is also much like that in Bathmodon. The osseous horn-
cores may be compared with those on the front of Loxolophodon.
The knee was probably free from the integument of the abdomen,
as in Proboscidians, In all other respects there is no approxima-
tion to this order.

Proboscidia. — The approximations to other orders in the
structure of the feet are only to be seen in the Eocene genera
Bathmodon and Eohasileus. The latter, or its ally JJiyitatherium,
presents, according to Marsh, but four toes on the hind foot ; the
anterior has five. In the former point we have a resemblance to
Hippopotamus, but one of little significance, in view of the radical
differences between the two in the form of the astragalus, cal-
caneum, and cuboid bones. The former is essentially Proboscidian
in all respects, with the addition of a cuboid facet alongside of
and behind the navicular, as in Symhorodon ; thus constituting a
Perissodactyle character, but leaning to the forms of that order
which betray probably the closest, though slight, approach to the
omnivorous division of the Artiodactyla. Thus, while the Uinta-
theriidcB present the Proboscidian type of feet and molar dentition,

* Huxley, "Anatomy of the Vertebrated Animals," p. 321.
f "American Journal of Science and Arts," 1873, p. 486.

i This should be Amblypoda, not separated from the Proboscidia at the time
this was written. (Ed. 1886.)

266 THE STRUCTURAL EVIDENCE OF EVOLUTION.

if they present any ordinal characters resembling those of the
Artiodactyla, they are equally shared by certain extinct Perisso-
dactyla.

From the hints above furnished, we may regard the succession
of modifications of foot-structure to be nearly as follows ;

Ruminantia. Rhinocerus. Equus. Elephas.

Omnivora. Palseotheriura. Hyracotherium.*

\ / /

Sjinborodoa. Palseosyops. Uintatherium.

\ / /

x/ /

, * Bathmodon.

\ /

\v //

\ /

VI. THE ANCESTRAL TYPE OF MAMMALIA EDUCABILIA.

I trust that I have made it sufficiently obvious that the primi-
tive genera of this division of mammals must have been Buno-
donts with pentad actyle plantigrade feet. It therefore follows that
Eleplias was not the descendant of Eoiasileus nor Bathmodon in
a direct line, but from some common ancestor with tubercular
teeth, through Mastodon. We may anticipate the discovery of
such a genus, and believe that it will not be widely removed from
the Eocene Hyopsodus, or perhaps Achcenodon. This will, then,
be the primitive ungulate.

But it will be more than this ; it can not be far removed from
the primitive carnivore and the primitive quadrumane. The Car-
nivora are all modified bunodonts, and the lower forms ( Ursus
Procyon, e. g.) are pentadactyle and plantigrade. As to the
Quadrumana, man himself is a pentadactyle plantigrade buno-
dont. This view has been already expressed, as follows: '^^The
type of Tomitlierium, already described, evidently stands between
lemurine monkeys and such small allies of Palmotlieriidm with
conic tubercular teeth {Oligotomus, OrotJierium,\ etc.), and which
abound in the Eocenes of Wyoming. . . . The dentition of the
two types is, indeed, but little different in the Quadrumanous and

* This was called Hipposyus in the original essay — a name which really applies
to a different type. (Ed. 1886.)

t Both these are names for Pliolophus, a close allay of Ilyracotherium. (Ed.

1886.)

MOLAR TEETH OF THE MAMMALIA EDUCABILIA. 267

Ungulate types respectively, being a continuous series of I. 1 or
2 ; C. 1 ; P. m. 3 — 4 ; M. 3 ; the canines but moderately devel-
oped. "* Such a hypothetical type might be expressed by the
name BunotlieriidcB, with the expectation that it will present sub-
ordinate variations in premolar, canine, and incisor teeth. The
premolars might be expected to differ in the degree of development
of the internal lobes, the canine in its proportions, and the incisors
in their number.

In respect to the limbs proper, neither the Quadriimana nor
Carnivora attain to the specialization seen in the Artiodactyla
and Perissodadyla, for the ulna and fibula are never atrophied
nor co-ossified with the radius and tibia, but are always distinct
and free ; the only modification of structure in these points being
the slight one involved in developing the rotary capacity seen in
the higher monkeys.

Thus the human series preserves in its feet, limbs, and den-
tition, more of the characteristics of the primitive Bunotlieriwn
than any other line of descent of the Mammalia EducaMlia. It
even exhibits a retrogression, in the transition from the anisog-
nathous Tomitherium to the genus Homo, where the teeth in the
two jaws are exactly alike, as well as in the resumption of the
continuity of the dental series after the diastema had prevailed
among the higher monkeys. In one respect it has steadily ad-
vanced, viz., in the number of convolutions and extent of the
cerebral hemispheres and relative size of the brain as a whole.

Note (Ed. 188fi). — As remarked in a previous note, the discovery of the general
characters of the genus Phenacodus in 1881, more than six years after the publica-
tion of this paper, demonstrated the truth of the hypothesis here proposed, viz. :
that the ancestor of the Mammalia Educabilia was a pentadactyle plantigrade buno-
dont. The numerous genera and species allied to Phenacodus have been placed in
a suborder Condylarthra. See " American Naturalist," 1884, 790, for an illustrated
article on this group.

Ilayden's " Geological Survey of Montana," etc., 1872, p. 645.

VIII.

THE EELATION OF MAN TO THE TERTIARY

MAMMALIA.*

Ii^" order to prove the affirmative of a doctrine of evolution by
descent of the existing types of living beings, two propositions

must be established. The first,
that a relation of orderly succes-
sion of structure exists, which
corresponds with a succession in
time. Second, that the terms
(species, genus, etc.) of this suc-
cession actually display transitions
or connection by intermediate
forms, whether observed to arise
in descent, or to be of such vari-

Fia. AA.-Periptychm rhabdodon part ^^^^ character aS to admit of nO
of posterior foot, two thirds natural size ; • ^ i • • •

b, astragalus from above, showing flat other explanation of their origin

face; e, metatarsals, the first lost, show- than that of deSCCnt..

ing plantigrade foot. Original; from j^ ^|-^g g^i^j ^f paleontology it

Puerco Epoch of New Mexico. . ., -i i j t 7 i

IS quite possible to demonstrate
the first of these propositions, while the proof of the second is
necessarily restricted to the observation of variations and the dis-
covery of connecting forms which destroy the supposed definitions
of species, genera, etc. The conditions are more favorable for the
investigation of animals of the higher types than of those of the
lower. Their late origin insures to us the opportunity of discovery
of their ancestry far more certainly than in the case of the lower,
whose beginnings are lost in the remote past, and belong to periods
whose deposits have undergone physical changes, or have been en-
tirely removed and redeposited elsewhere, thus insuring the de-
struction of the fossil remains once contained in them. The series
of the tertiary Mammalia is becoming more complete through the

* Read before the American Association for the Advancement of Science, at
Detroit, 1875, under another title.

EELATION" OF MAN TO THE TERTIARY MAMMALIA.

269

Fig. 45. — Caryphodon elepJiantopiLS^ anterior
foot from above, one third natural size. From
Lower Eocene of New Mexico. The cuneiform
{Cu) is injured. (Original.)

recent explorations in the West, and the results are embraced in

the forthcoming quarto

reports of the Hayden and z^^^fc^^'^K^S'c

Wheeler U. S. Geological, Cu

etc., surveys of the Terri- ^'n-

tories. An abstract of

some of these is given in

the present essay.

The primary forms of
the Mammalia repose in
great measure on the struc-
ture of the feet. Those of
the teeth are also very sig-
nificant, but present a
greater number of varia-
tions among animals other-
wise nearly related. The
osteology of the feet of re-
cent land mammals falls into several categories. These may be

called the plantigrade,
many-toed type ; the car-
nivorous type ; the horse
type, and the ruminant
(e. g., ox) type. The
lower vertebrates, as sala-
manders, lizards, etc., dis-
play the simplest form of
feet, having usually five
toes, with numerous sepa-
rate bones of the palm
and the sole, which they
apply to the ground in
progression. The many-
toed or multidigitate
type of mammalian foot
most nearly resembles
this condition, but dif-

FiG. 46.— Posterior foot of CorypTiodon elephan- fers in the points of dif-
topus. From Lower Eocene of New Mexico. (Orig- f p^'ence which are Com-
mon to all Mammalia.
In the hind foot a succession of forms leads from this general-

270 THE STRUCTURAL EVIDENCE OF EVOLUTIOK

ized type to the extreme specializations observed in the horse and
the ox.

The modifications are as follows : The hind foot is composed
of two rows of tarsal bones, of which the second is followed by
the long metatarsal bones, from which the bones of the toes origi-
nate. The second segment of the hind leg is composed of two
boues, tibia and fibula, which in the salamander, etc., have a sub-
equal union with the foot. In some multidigitates, as the genus
Corypliodon, both these bones articulate with the
two bones of the first row of the tarsus, and one
(fibula) is the smaller of the two. In many higher
forms they articulate with but one of these tar-
sal bones, viz., the astragalus, with which they
form a perfect hinge joint ; the other tarsal bone
of the first row is the
calcaneum or heel-bone.
In Coryjjliodon the as-
tragalus and the applied
leg-bone (tibia) are near-
ly flat, offering an ex-
tremely imperfect hinge
for the foot, and the
heel-bone (calcaneum)
is exceedingly short.
The animal plainly
walked on the entire
sole of the foot, and
must have had an awk-
ward gait, from the Fig. 47.— Left anterior
slio'ht power of flexins^ ^ooX.oi Phenacodus primal- foot of PTienacodusprimos,-

the ankle-joint. From ""''^^"^- '^''- ^^"^^-^ t^^«, K nat. size. (Orig.)
this point to the horse on one side, and to the ox on the other, we
have a line of succession of intermediate forms. And before de-
scribing them, I may state that the Corypliodon is one of the old-
est known Mammalia, its remains having been found in the Lower
Eocene Tertiary of New Mexico and Wyoming, while the ox and
horse are extremely modern animals, their advent on the earth
having preceded that of man by but one geological period.

The most perfect ankle-joint is that of the ruminating animals.
The astragalus presents a deeply grooved segment of a pulley ; an
angulated pulley, face downward to the rest of the foot, and a

Fig. 48. — Left posterior

PLATE VI.

272 THE STRUCTURAL EVIDENCE OF EVOLUTION.

smooth convexity to the hollow of the applied heel-bone behind.
No such astragalus has ever been found in the Lower Eocene forma-
tions of America ; animals bearing it in a less perfect stage appear
in the next higher period, the Miocene ; but it is not until the
Pliocene and modern times that they abound. In the Hipjwpota-
mus foot, we have an example of the less perfect astragalus of this
type of animals. The pulley surfaces
are flatter and less deeply grooved.

In the horse, the upper surface
of the astragalus forms as perfect

>7mrve /irfaulan

POLLICIS

Cfjrpi'S

eJT. CARPI ULNAR IS

pni»M
RNoan

nir</f»

EXT. COWMUNIS
DICITORUM
EKI.INOICIS

EXT COMMUNIS
DlGlTOPtM

Fig. 49. — Anterior foot of Homo sapiens from
above, one tliird natural size. From Allen's
Anatomy.

Omnvf /tff

(>ER0NELIS1,0NCUS

Oroox-t* for
PONEUS BPEVIS

3liicn:/e/ororoyiit o^
AS: OIN. Die.

Fig. 50. — Posterior foot of do.
from above, one third natural
size. From Allen's Anatomy.

a joint as in ruminants, but the lower and hinder faces present
the flattened surfaces which belong to the many-toed Mammalia.
The lower face especially is mainly occupied by one large facet, in-
stead of the two-faced pulley of the ruminants. In the rhinoceros
a later facet is more distinct, while in the Miocene Menodus the
second facet is larger, resembling, except in the still convex tibial
articulation, the structure of that of the primitive Corypliodon.

RELATION OF MAN" TO THE TERTIARY MAMMALIA. 273

In the heel-bone we have a succession from the short and flat
form of Coryphodon to the long and slender one of the horse and
ruminants ; the increase in length being associated with the elon-
gation of the bones of the toes, and the assumption of the digiti-
grade type from the planti-
grade. The mammals of the
Lower Eocene* exhibit a
greater percentage of types
that walk on the entire sole
of the foot, while the suc-
ceeding periods exhibit an
increasing number of those
that walk on the toes, while
the hoofed animals and Car-
nivora of recent times nearly
all have the heel high in the
air, the principal exceptions
being the elephant and the
bear families.

A most noticeable succes-
sion is seen in the diminu-
tion of the number of toes.
In the series leading to the
horse, the ox, and the hyaena
and cat, this reduction pro-
ceeds by the loss of a toe
from the one side or the
other, until in the ruminants
but two are left, and in the
horse but one. The series ex-
tending from the primitive
Eocene types with five digits,
to the existing reduced forms,

is most complete, although Fig. b\.—Phenacodus primcevus skull, one

a few of the New Mexican third natural si^e, from below, showing quadri-
-c^ ,1 1 tubercular true molars. From specimen figured

Eocene genera themselves , . r &

^ _ on plate.

probably exhibit but four

digits on one or both pairs of feet. The presence of the rudiments

* All the Mammalia of the Puerco fauna (which was unknown at the time this
lecture was delivered) are plantigrade. (Ed. 1886.)

274 THE STRUCTURAL EVIDENCE OF EVOLUTION.

of the lost lateral digits is constantly observed, and when these
disappear it is to be finally replaced by the rudiments of the ad-
joining toes in i^rocess of similar reduction. The bones of the sec-
ond row of the tarsus which are in connection with the toes are
not reduced so rapidly as the toes themselves; hence, the bones of
the toes, in order to maintain the fit of the i^arts, increase in
width, and consequently in strength. As is well known, in the
horse the single toe is as stout as several united toes of lower
forms, and the two toes of the ruminants have their basal seg-
ments (metatarsals) united into a stout solid mass, the cannon-
bone. At the same time several of the small bones of the sec-
ond tarsal row become coossified, so that we have, in the rumi-
nants and horse, the greatest consolidation of structure, connected
in the former with the most elegant mechanism. It is scarcely
necessary to add that, in the various cases of coossification and
consolidation described, the foetus displays the original elements
separated.

In the fore limb the same successional reduction in the number
of toes may be traced as I have described in the hind foot ; but,
as the bones of the palm differ from those of the sole, the succes-
sional modification of these is also characteristic. The bones of
the second row of the carpus are four in number, but as the toes
are reduced, in the lines of the hoofed animals, the inner (tra-
pezium) is soon dropped, and the second (trapezoides) becomes
united with the third (magnum). In the carnivorous order, the
trapezoides is always separate, but the inner pair of bones of the
first row (scaphoid and the lunar) become consolidated into a single
mass, although their original distinctness is easily determined by
examination of the foetus.

The two bones of the leg which articulate with the foot and
hand, exhibit a succession of changes of relation in progress to-
ward the more specialized types. In the Corypliodon and Umta-
therium of the Eocene, each of these bones has considerable share
in the articulation ; but as we rise in the series, the surface of at-
tachment of the lesser bones, the fibula in the foot, and the ulna
in the hand, becomes successively smaller, until in the ruminants
the fibula is almost obliterated, its distal end remaining as a small
tuberosity coossified to the side of the end of the tibia. In the
same manner the articular end of the ulna in the fore leg is suc-
cessively reduced, until this bone also becomes a thin strip coossi-
fied to the lower side of the radius, with no distinct termination.

PLATE VIL

pec...

Fia. 5.

Fig. 7.

acQ

-ax

Fig. 9.

acc

Fig. 2.

Fig. 4.

ktti' ai pi

pi Pe ji

Fig. 6.

ai aV P}

Fig. 8.

ae y

—-h

Fig. 10.

Fig. 1, Mioclaenus corrxigatus^ superior molars. Fisf. 2, Pantolambda hathmodon^
superior true molars. Fig. 3, Phenacodus primcevus, superior molar. Fig. 4, do. inferior
molar. Fig. 5, Lambdotherium popoagicum^ superior molar. Fig. 6, do. inferior molar.
Fig. 7, AncMtherium anrelianense, superior molar. Fig. 8, Hippotlieriu'm gracile^ infe-
rior molar. Fig. 9, superior molar young crown of a Hippotherium. Fig. 10, superior
molar of Equus. Figs. 1, 2, 5, 6, from Cope ; 3, 4, from Wortman ; the others from
'"audry.

276 THE STRUCTURAL EVIDENCE OF EVOLUTION.

in both the horse and the ox. In the foetus these bones are well
distinguished.

The dentition tells as clearly as possible the same story. Here,
again, as I have pointed out in a paper on the ** Homologies and
Origin of the Types of Dentition of the Mammalia Educahilia,^''
the most specialized forms of dental structure are presented by the
horse, the ox, and the tiger. But they are all modifications of a
single type of tooth, viz., an oval crown supporting four tubercles
on the summit, in the lower jaw, and three or four in the upper
jaw. In the lower cutting molar of the cat but one of these tu-
bercles remains, forming with another in front of it a double shear
blade, whose development may be traced from its earliest begin-
nings in the genera of the Eocene. In the odd-toed forms (tapir,
rhinoceros, etc.) the tubercles become connected transversely,
forming cross-crests, and the outer ones are generally flattened on
the outer side. In the horse the tubercles have a very complex
form, and the spaces between them filled by a peculiar substance,
the cementum. In the ruminants the tubercles come to have a
crescent-shaped section and are drawn out to an enormous length,
forming a prismatic tooth : here, also, the intervening deep valleys
are filled with cementum. . In the third series, that of the ele-
phant, the original tubercles (permanently separate in the masto-
dons) are connected into cross-crests, which are drawn out to a
great length, and as in the other series are supported by a deposit
of hard cementum in the intervening valleys. The transitions be-
tween these and the primitive four-tubercled molar are numerous
and direct.

There is not now opportunity to consider the question of tran-
sition from type to type by descent, further than to indicate by a
few examples the manner in which it has evidently occurred.
This has been by unequal growth of parts during foetal life, ac-
cording to the laws of acceleration and retardation. The union
of the two basal bones of toes into a single one (the "cannon-
bone ") in the ruminants, is accomplished by the more and more
rapid completion of the process of ossification in the growth of
those bones ; the confluence of the various carpal and tarsal bones
in various orders has the same history. In many genera it has
been observed that the milk dentition has resemblances to other
and older dentitions, which entirely disappear in the permanent
teeth. This is the case with Coryphodon and Equus ; while it
may be observed in the kitten, whose sectorial milk-tooth has the

PLATE VIII.

278 THE STRUCTURAL EVIDENCE OF EVOLUTION.

heel belonging to all the lower and primitive Carnivora which is
wanting from the sectorial of the adult cat. Moreover, in complex
teeth, the different stages of wear represent primitive conditions
of the same animal, elsewhere preserved to us in extinct adult
genera and species.

Forms which violate the definitions of the orders above given
are also well known. Thus Mesonyx, with the skull and denti-
tion of a carnivore, has the separate scaphoid and lunar bones and
flat claws or hoofs of an ungulate. Calamodon has the molars
of an ungulate, the incisors of a rodent, and claws resembling
somewhat those of a carnivore. Uintatlierium has feet partly like
an elephant, and teeth of a tapir.

I have referred the Mammalia with five and four toes, the full
number of distinct tarsal and carpal bones, which form interlock-
ing series, and in which the tread is plantigrade, to a new order
called the AmUyjJoda. These represent the primitive type of the
higher Mammalia with convoluted brains, etc., but present much
variation in the constitution of the teeth. From the latter have
come off not only the three hoofed-orders represented by the ele-
phant, the horse, and the ox, but the origin of the Carnivora and
Quadrwnana is scarcely distinguishable from it, if at all ; while
there is little doubt that the natatory Sireniaii order was derived
from it by a process of degradation, chiefly of the extremities, in
connection with the assumption of an aquatic life. The mana-
tee, of which a fine example may now be seen in our zoological
gardens, represents this division.

The relation of man to this history is highly interesting. Thus
in all general points his limbs are those of the primitive type so
common in the Eocene. He is plantigrade, has five toes, separate
carpals and tarsals ; short heel, rather flat astragalus, and neither
hoofs nor claws, but something between the two. The bones of
the forearm and leg are not so unequal as in the higher types, and
remain entirely distinct from each other, and the ankle-joint is
not so perfect as in many of them. In his teeth his character is
thoroughly primitive. He possesses, in fact, the original quadri-
tuberculate molar with but little modification. His structural
superiority consists solely in the complexity and size of his brain.
The forms of the quadrumanous order, while agreeing with each
other in most respects, display the greatest range of brain struct-
ure, and show that while they have made but little progress since
the Eocene in perfection of organization of the skeleton, they

PLATE IX.

Fig. 7.

Fig. 1.

Fig. 4.

C V ^

Fig. 5.

Fig. 6.

Fig. 8.

COMPAEISOK BETWEEN THE DENTITION OF THE LEirtJE AnAPTOMORPHUS AND MaN.

Fig. 1, skull of Anaptomovplixis Tiormmctdus^ natural size. Fig. 2, same, oblique
view, displaying the large cerebral hemispheres ; compare Plate XIV for relatively small
size in a contemporary (Fig. 3) or a successor in time (Fig. 2). Fig. 3, superior view of
skull, natural size. Fig. 4, inferior view, 3/2 natural size. Figs. 5, 6, and 7, left branch of
lower jaw of Anaptomorphus cemulus, twice natural size; 5, from left side; 6, inner
Bide ; 7, from above. Fig. 8, superior dentition of Homo sapiens (from Alien), natural
size.

280 THE STRUCTURAL EVIDENCE OF EVOLUTION.

accom23lished a mucli greater work, the eyolution of tlie human
brain and its functions.

A very important lesson is derived from these and kindred facts.
The monkeys were anticipated in the greater fields of the world's
activity by more powerful rivals ; the ancestors of the ungulates
held the fields and the swamps, and the Carnivora, driven by hun-
ger, learned the arts and cruelty of the chase. The weaker an-
cestors of the Quadrumana possessed neither speed nor weapons
of offense and defense, and nothing but an arboreal life was left
them, where they developed the prehensile powers of the feet.
Their digestive system unspecialized, their food various, their life
the price of ceaseless vigilance, no wonder that that quality of in-
quisitiveness and wakefulness was stimulated and developed which
is the condition of progressive intelligence. So *' the race has not
been to the swift nor the battle to the strong" ; the *' survival of
the fittest" has been the survival of the most intelligent, and
natural selection proves to be, in its highest animal phase, intel-
ligent selection.

IX.

THE DEVELOPMENTAL SIGNIFICANCE OF HUMAN

PHYSIOGNOMY.*

The ability to read character in the form of the human face
and figure is a gift possessed by comparatively few persons, al-
though most people interpret, more or less correctly, the salient
points of human expression. The transient appearances of the
face reveal temporary phases of feeling which are common to all
men ; but the constant qualities of the mind should be expressed,
if at all, in the permanent forms of the executive instrument of
the mind, the body. To detect the peculiarities of the mind by
external marks has been the aim of the physiognomist of all
times ; but it is only in the light of modern evolutionary science
that much progress in this direction can be made. The mind, as
a function of part of the body, partakes of its perfections and its
defects, and exhibits parallel types of development. Every pecu-
liarity of the body has probably some corresponding significance in
the mind, and the causes of the former are the remoter causes of
the latter. Hence, before a true physiognomy can be attempted,
the origin of the features of the face and general form must be
known. Not that a perfect physiognomy will ever be possible. A
mental constitution so complex as that of man can not be expected
to exhibit more than its leading features in the body ; but these
include, after all, most of what it is important for us to be able to
read from a practical point of view.

The present essay will consider the probable origin of the
structural points which constitute the permanent expression.
These may be divided into three heads, viz. : (1) Those of the
general form or figure ; (2) those of the surface or integument of
the body with its appendages ; and (3) those of the forms of the

* Abstract of a lecture delivered before the Franklin Institute of Philadelphia,
January 20, 1881, in exposition of principles laid down in "The Hypothesis of Evo-
lution," New Haven, 1870, p. 31.

282 THE STRUCTURAL EVIDEN^OE OF EVOLUTION".

head and face. The principal points to be considered under each
of these heads are the following :

7. The General Form.

1. The size of the head.

2. The squareness or slope of the shoulders.

3. The length of the arms.

4. The constriction of the waist.

5. The width of the hips.

6. The length of the leg, principally of the thigh.

7. The sizes of the hands and feet.

8. The relatiye sizes of the muscles.

//. The Surfaces.

9. The structure of the hair (whether curled or not).

10. The length and position of the hair.

11. The size and shape of the nails.

12. The smoothness of the skin.

13. The color of the skin, hair, and irides.

III. The Head and Face.

14. The relative size of the cerebral to the facial regions.

15. The prominence of the forehead.

16. The prominence of the superciliary (eyebrow) ridges.

17. The prominence of the alveolar borders (jaws).

18. The prominence and width of the chin.

19. The relation of length to width of skull.

20. The prominence of the malar (cheek) bones.

21. The form of the nose.

22. The relative size of the orbits and eyes.

23. The size of the mouth and lips.

The significance of these, as of the more important structural
characters of man and the lower animals, must be considered from
two standpoints, the paleontological and the embryological. The
immediate paleontological history of man is unknown, but may
be easily inferred from the characteristics displayed by his nearest
relatives of the order Quadrumana. If we compare these animals
with man, we find the following general differences. The num-
bers correspond to those of the list above given.

HUMAN PHYSIOGNOMY.

283

/. As to General Form, — (3) In the apes the arms are longer ;
(8) the extensor muscles of the leg are smaller.

//. As to Surface, — (9) The body is covered with hair which
is not crisp or woolly ; (10) the hair of the head is short ; (13) the
color of the skin, etc., is dark,

///. As to Head and Face. — (14) The facial region of the
skull is large as compared with the cerebral ; (15) the forehead is

Fig. 52. — Section of skull of adult orang-outang {Simla safyrus). «, section of
skull of young orang, showing; relatively shorter jaws and more prominent cerebral
region.

not prominent, and is generally retreating ; (16) the superciliary
ridges are more prominent ; (17) the edges of the jaws are more
prominent ; (18) the chin is less prominent ; (20) the clieek-bones
are more prominent ; (21) the nose is without bridge, and with
short and flat cartilages ; (22) the orbits and eyes are smaller
(except in Nyctipithecus) ; (24) the mouth is small and the lips
are thin.

It is evident that the possession of any one of the above char-
acteristics by a man approximates him more to the monkeys, so

284: THE STRUCTURAL EVIDENCE OF EVOLUTION.

far as it goes. He retains features wliicli have been obliterated in
other persons in the process of evolution.

In considering the ph3'siognomy of man from an embryological
standpoint, we must consider the peculiarities of the infant at
birth. The numbers of the following list correspond with those
already used (Fig. 53).

/. As to the General Form. — (1) The head of the infant is rel-
atively much larger than in the adult ; (3) the arms are relatively

longer; (4) there is no waist;
(6) the legs, and especially
the thighs, are much shorter,
//. As to the Surfaces. —
(10) The body is covered with
fine hair, and that of the
head is short.

///. The Head and Face.
— (14) The cerebral part of
the skull greatly j^redomi-
nates over the facial ; (16)
the superciliary ridges are
not developed ; (17) the al-
veolar borders are not prom-
inent ; (20) the malar bones
are not prominent ; (21) the
nose is without bridge and
the cartilages are flat and
generally short ; (22) the
eyes are larger.

It is evident that per-
sons who present any of the
characters cited in the above
list are more infantile or em-
bryonic in those respects than
are others ; and that those who lack them have left them behind
in reaching maturity.

We have now two sets of characters in which men may differ
from each other. In the one set the characters are those of monk-
eys, in the other they are those of infants. Let us see whether
there be any identities in the two lists, i. e., whether there be any
of the monkey-like characters which are also infantile. We find
the following to be such :

Fig. 53. — ^Figure of infant at birth; a, front
of face.

huma:n' physiognomy.

285

L As to General Form. — (3) The arms are longer.

//. Surface. — (10) The hair of the head is short, and the hair
on the body is more distributed.

///. As to Head and Face. — (21) The nose is without bridge,
and the cartilages are short and flat.

Three characters only out of twenty- three. On the other hand,
the following characters of monkey-like significance are the oppo-
sites of those included in the embryonic list : (14) The facial re-
gion of the skull is large as compared with the cerebral ; (15) the
forehead is not prominent ; (16) the superciliary ridges are more

¥iQ. 54.

i'lG. 55.

Fig. 54. — Portrait of a girl at five years of age. Fig. 55. — Portrait of the same at
seventeen years, showing the elongation of the facial region, and less protuberance of
the cerebral.

prominent ; (17) the edges of the jaws are more prominent. Four
characters, all of the face and head. It is thus evident that in at-
taining maturity man resembles more and more the apes in some
important parts of his facial expression.

It must be noted here that the difference between the young
and embryonic monkeys and the adults is quite the same as those
just mentioned as distinguishing the young from the adult of man
(Figs. 1-2). The change, however, in the case of the monkeys is
greater than in the case of man. That is, in the monkeys the
jaws and superciliary ridges become still more prominent than in

PLATE X.

Esequibo Indian women, showing the following peculiarities : deficient bridge of
nose, prognathism, no waist, and deficiency of statm-e through short femur. From
photographs by Endlich.

HUMAN PHYSIOGNOMY.

287

man. As these characters result from a fuller course of growth,
from the infant, it is evident that in these respects the apes are
more fully developed than man. Man stops short in the develop-
ment of the face, and is in so far more embryonic* The promi-
nent forehead and reduced jaws of man are characters of " retar-
dation." The characters of the prominent nose, with its elevated
bridge, is a result of ^* acceleration," since it is a superaddition to
the quadrumanous type from both the standpoints of paleontology
and embryology. f The development of the bridge of the nose is
no doubt directly connected with the development of the front of
the cerebral j)art of the skull and ethmoid bone, which sooner or
later carries the nasal bones with it.

If we now examine the leading characters of the physiognomy
of three of the principal human sub-sj)ecies, the Negro, the Mon-

FiG. 56.

Fig. 57.

Fig. 56, — Profile of a Lucliatze negro woman, sbowin;? deficient bridge of nose and
chin, and elongate facial region and prognathism. Fig. 57. — Face of another Luchatze,
showing flat nose, less prognathism and larger cerebral region. From Serpa Pinto.

golian, and the Indo-European, we can readily observe that it is
in the two first named that there is a predominance of the quad-
rumanous features which are retarded in man ; and that the em-
bryonic characters which predominate, are those in which man is

* Thi3 fact has been well stated by C. S. Minot, in the "Naturalist " for 1882,
p. 511.

f See Cope, " The Hypothesis of Evolution," New Haven, 1870, p. 31.

288

THE STRUCTURAL EVIDENCE OF EVOLUTION

accelerated. In race description the prominence of the edges of

the jaws is called prognathism, and its absence orthognathism.

The significance of the two lower race characters, as compared

with those of the Indo-European, is as follows :

Negro. — Hair crisp (a special character), short (quadrnm. ac-

cel.) ; prognathous (quadrum. accel.) ; nose flat, without bridge

(quadrum. retard.) ;* malar bones prominent (quadrum. accel.) ;

beard short (quadrum. retard.) ; arms longer (quadrum. accel.) ;

extensor muscles of legs small (quadrum. retard.).

Mongolian. — Hair straight, long (accel.) ; jaws prognathous

(quadrum. accel.) ; nose flat or prominent, with or without bridge ;

malar bones prominent
(quadrum. accel.) ; beard
none (embryonic) ; arms
shorter (retard.) ; extensor
muscles of leg (''calf")
smaller (quad, retard.).

Indo-European. — Hair
long (accel.) ; jaws orthog-
nathous (embryonic re-
tard.) ; nose (generally)
prominent with bridge
(accel.) ; malar bones re-
duced (retard.) ; beard
long (accel.); arms shorter
(retard.) ; extensor mus-
cles of the leg large (accel.).
The Indo - European
race is then the highest by
virtue of the acceleration
of growth in the develop-
ment of the muscles by
which tiie body is main-
tained in the erect position

Fig. 58.— Portrait of Satauta, a late chief of the (extensorS of the leg), and

Kiowas (from the Ked Eiver of Texas), from a j^ those important elc-
pfiotoarraph. The predominance of the facial re- + -p v. i

gion, and especially of the malar bones, and the ^^nts 01 beauty, a WCll-

absence of beard, are noteworthy. developed nose and beard.

* In the Bochimans, the flat nasal bones are coossified with the adjacent ele-
ments as in the apes (Thulie).

PLATE XL

'■'V;;:;:Vi;:V;::;/;r'!'-.

^'S^\ii\^■'l■■r,l,,;■\^.v.i\\\t,</,:■■■,■,'.l;i■ri■ ,■:••-.•.

j^- -'--,.A','f»J^i^r^v?,.V,y.V^»>';I'.'->a

The Wrestler ; original in the Vatican. This figure displays the characters of the
male Indo-European, except the beard.
19

290 THE STRUCTURAL EVIDENCE OF EYOLUTION.

It is also superior in those points in which it is more embryonic
than the other races, viz., the want of prominence of the jaws
and cheek-bones, since these are associated with a greater predom-
inance of the cerebral part of the skull, increased size of cerebral
hemispheres, and greater intellectual power.

A comparison between the two sexes of the Indo-Europeans
expresses their physical and mental relations in a definite way. I
select the sexes of the most civilized races, since it is in these, ac-
cording to Broca and Topinard, that the sex characters are most
pronounced. They may be contrasted as follows. The numbers
are those of the list on page 282, already used. I first consider
those which are used in the tables of embryonic, quadrumanous,
and race characters :

MALE. FEMALE.

/. The General Form.

2. Shoulders square. Shoulders sloped.

4. Waist less constricted. Waist more constricted.

5. Hips narrower. Ilips wider.

6. Legs longer. Legs shorter (very frequently).
8. Muscles larger. Muscles smaller.

II. The Integuments^ etc.

10. More hair on body, that of head Less hair on body, that of head longer ;

shorter ; beard. no beard.

12. Skin rougher (generally). Skin smoother.

III. TJie Head and Face.

16. Superciliary ridges more prominent. Superciliary ridges low,
22. Eyes often smaller. Eyes often larger.

The characters in which the male is the most like the infant
are two, viz., the narrow hips and short hair. Those in which the
female is most embryonic are five, viz., the shorter legs, smaller
muscles, absence of beard, low superciliary ridges, and frequently
larger eyes. To these may be added two others not mentioned in
the above lists ; these are (1) the high-pitched voice, which never
falls an octave as does that of the male ; and (2) the structure of
the generative organs, which in all Mammalia more nearly resem-
ble the embryo and the lower Vertebrata, in the female than in the
male. Nevertheless, as Bischoff has pointed out, one of the most
important distinctions between man and the apes is to be found
in the external reproductive organs of the female.

From the preceding summary sketch the reader will be able to
explain the meaning of most of the peculiarities of face and form

HUMAIT PHYSIOGNOMY.

291

which he will meet with. Many persons possess at least one quad-
rumanous or embryonic character. The strongly convex upper lip
frequently seen among the lower classes of the Irish is a modified
quadrumanous character. Many people, especially those of the
Sclavic races, have more or less embryonic noses. A retreating
chin is a marked monkey character. Shortness of stature is mostly

Fig. 59, — Australian native (from Brough Smyth), showing small development oi
muscles of legs, and prognathism.

due to shortness of the femur, or thigh ; the inequalities of people
sitting are much less than those of people standing. A short femur
is embryonic ; so is a very large head. The faces of some people
are partially embryonic, in having a short face and light lower
jaw. Such faces are still more embryonic when the forehead and
eyes are protuberant. Retardation of this kind is most frequently

PLATE XIL

The Venus of the Capitol (Rome). The form and face present the characteristic
paculiarities of the female of the Indo-European race.

HUMAN PHYSIOGNOMY. 293

seen in children, and more frequently in women than in men. The
length of the arms would appear to have grown less in compar-
atively recent times. Thus the humerus in most of the Greek
statues, including the Apollo Belvidere, is longer than those of
modern Europeans, according to a writer in the '^Bulletin de la
Societe d' Anthropologic " of Paris, and resembles more nearly that
of the modern Nubians than any other people. This is a quad-
rumanous approximation. The miserably developed calves of
many of the savages of Australia, Africa, and America, are well
known. The fine swelling gastrocnemius and soleus muscles char-
acterize the highest races, and are most remote from the slender
shanks of the monkeys. The gluteus muscles developed in the
lower races as well as in the higher, distinguish them well from
the monkeys with their flat posterior outline.

It must be borne in mind that the quadrumanous indications
are found in the lower classes of the most developed races. The
status of a race or family is determined by the percentage of its
individuals who do and do not present the features in question.
Some embryonic characters may also appear in individuals of any
race, as a consequence of special circumstances. Such are, how-
ever, as important to the physiognomist as the more normal vari-
ations.

Some of these features have a purely physical significance, but
the majority of them are, as already remarked, intimately con-
nected with the development of the mind, as an effect or necessary
coincidence. I will examine these relations in a future article.

THE EVIDENCE FOR EVOLUTION IN THE HIS-
TORY OF THE EXTINCT MAMMALIA.*

The subject to which I wish to call your attention this morn-
ing requires neither preface nor apology, as it is one with the dis-
cussion of which you are perfectly familiar. I bring it before the
general session of the Association in view of the fact that you
are all familiar with it in a general way, and that it probably in-
terests the members of sections who do not pursue the sjoecial
branch to which it refers, as well as those who do : also, since it
has been brought before us in various public addresses for many
years, during the meetings of this Association, I thought it might
be well to introduce it at this meeting, in order that we might
not omit to have all the sides of it presented.

The interests which are involved in it are large : they are
chiefly, however, of a mental and metaphysical character ; they
do not refer so much to industrial and practical interests, nor do
they inyolve questions of applied science. They involve, however,
questions of opinion, questions of belief, questions which affect
human happiness, I venture to say, even more than questions of
applied science ; certainly, which affect the happiness of the
higher grades of men and women more than food or clothing, be-
cause they relate to the states of our mind, explaining as they do
the reasons of our relations to our fellow beings, and to all other
things by which we are surrounded, and the general system of the
forces by which we are controlled. So it has always appeared to
me : hence I have selected the department of biology for study,
and have taken a great interest in this aspect of it.

The doctrine of evolution, as taught by the biologists of to-
day, has several stages or parts of its presentation. First, the
foundation principle is this : that the species of animals and of

* An address delivered before the American Association for the Advancement of
Science, 1883.

THE EXTINCT MAMMALIA. 295

plants, the species of organic beings, as well as the yarious natu-
ral divisions into which these organic beings fall, have not always
been as we see them to-day, but they have been produced by a
process of change which has progressed from age to age through
the influence of natural laws ; that, therefore, the species which
now exist are the descendants of other species which have existed
heretofore, by the ordinary processes of reproduction ; and that
all the various structures of organic beings, which make them
what they are, and which compel them to act as they now act,
are the result of gradual or sudden modifications and changes
during the periods of geologic time. That is the first phase or
aspect which meets the naturalist or biologist.

Another phase of the question relates to the origin of that life
itself which is supposed to inhabit or possess organic beings.
There is an hypothesis of evolution which derives this life from
no-life, which derives vitality from non-vitality. This is another
branch of the subject, to which I can not devote much attention
to-day.

There is still another department of the subject, which relates
to the origin of mind, and which derives the mental organization
of the higher animals, especially of man, from pre-existent types
of mental organization. This gives us a genealogy of mind, a his-
tory of the production or creation of mind, as it is now j^resented
in its more complex aspects as a function of the human brain.
This aspect of the subject is, of course, interesting ; and upon
it I can touch with more confidence than upon the question of
the origin of life.

Coming now to the question of the origin of structures, we
have by this time accumulated a vast number of facts which have
been collated by laborious and faithful workers, in many countries
and during many years ; so that we can speak with a good deal of
confidence on this subject also. As to the phenomena which
meet the student of zoology and botany at every turn, I would
merely repeat what every one knows — and I beg pardon of my bio-
logical friends for telling them a few well-known truths, for there
may be those present who are not in the biological section — the
phenomena which meet the student of biology come under two
leading classes. The first is the remarkable fidelity of species in
reproducing their like. *^ Like produces like," is the old theo-
rem, and is true in a greiat many cases ; just as coins are struck
from the die, just as castings are turned out from a common

296 THE STRUCTURAL EVIDEXCK OF EYOLUTIOi^.

mold. It is one of the most wonderful phenomena of nature,
that such complex organisms, consisting of so many parts, should
be repeated from age to age, and from generation to generation,
with such surprising fidelity and precision. This fact is the first
that strikes the student of these sciences. The first impression
of the ordinary person would be, that these things must continue
unchanged. When I began to study zoology and botany, I was
surprised to find there was a science of which I had no concep-
tion, and that was this remarkable reproduction of types one
after another in continued succession. After a man has had
this idea thoroughly assimilated by his honest and conscien-
tious studies, he will be again struck with another class of
facts. He will find, not unfrequently, that this doctrine does
not apply. He will find a series of facts which show that many
individuals fail to coincide with their fellows precisely, the most
remarkable variations and the most remarkable half-way atti-
tudes and double-sided aspects occurring ; and he will come to
the conclusion, sooner or later, that like does not produce like in
some animals with the same precision and fidelity with which it
is accomplished in other animals. So that we have these two
classes of facts — the one relating to, and expressing, the law of
heredity ; the other which expresses the law of variation. I
should not like to say which class of facts is the most numerously
presented to the student. In the present fauna we find many
groups of species and varieties ; but exactly how many species we
have, how many genera and families we have, we can not defi-
nitely state. The more precise and exact a person is in his defini-
tion and in his analysis, the more definite his science becomes,
and the more precise and scientific his work. Biology is a science
of analvsis of forms. What the scales are to the chemist and the
physicist, the rule and measure are to the biologist. It is a ques-
tion of dimension, a question of length and breath and thickness,
a question of curves, a question of crooked shapes or simple
shapes — rarely simple shapes, mostly crooked, generally bilateral.
It requires that one should have a mechanical eye, and should
have also something of an artistic eye, to appreciate these forms,
to measure them, and to be able to compare and weigh them.

Now, when we come to arrange our shapes and our measure-
ments, we find, as I said before, a certain number of identities,
and a certain number of variations. This question of variation
is so common and so remarkable, that it becomes perfectly evi-

THE EXTINCT MAMMALIA. 297

dent to the specialist in each department, that like does not at
all times produce like. It is perfectly clear, and I will venture
the assertion that nearly all the biologists in this room will bear
me witness, that variability is practically unlimited in its range,
and multiplied in the number of its examples. That is to say :
species vary by adding or by failing to retain certain characteris-
tics ; and generic and other characters are found to appear or
disappear in accordance with some law to be discussed farther on.

I believe that this is the simplest mode of stating and explain-
ing the law of variation : that some forms acquire something
which their parents did not possess ; and that those which ac-
quire something additional have to pass through more numerous
stages than their ancestors ; and those which lose something pass
through fewer stages than their ancestors ; and these processes are
expressed by the terms *' acceleration " and *^ retardation."

Of course we are met with the opposite side of the case — the
law of heredity. We are told that the facts there are not ac-
counted for by any law of evolution ; that we can not pass from
one class of facts to the other class of facts ; that the law of the
one class is not that of the other. Here is a question of rational
processes, of ordinary reason. If the rules of chemistry are true
in America, I imagine they are true in Australia and Africa, al-
though I have not been there to see. If the law of gravitation is
effective here, I do not need to go to Australia or New Zealand
to ascertain whether it be true there. So, if we find in a group
of animals a law sufficient to account for their creation, it is not
necessary to know that others of their relatives have gone through
a similar process. I am willing to allow the ordinary practical
law of induction, the practical law of inference, to carry me over
these gaps, over these interruptions. And I state the case in this
way, because it is Just here that some people differ from me, and
it is Just here that I say the simple question of rationality comes
in. I can not believe that Nature's laws are so dissimilar, so
irregular, so inexact, that those which we can see and understand
in one place are not true in another ; I also believe that the ques-
tion of geological likelihood is similar to the question of geo-
graphical likelihood. If a given process be true in one of the
geological periods, it is true in another ; if it be true in one part
of the world, it is true in another ; because I find interruptions
in the series here, it does not follow that there need be interrup-
tions clear through from age to age. The assumption is on the

298 THE STRUCTUPwAL EVIDENCE OF EVOLUTION.

side of tlie man who asserts that transitions have not taken place
between forms which are now distinct.

We are told that we find no sort of evidence of that transition
in past geological periods ; we are assured that such changes have
not taken place ; we are even assured that no such sign of such
transition from one species to another has ever been observed — a
most astonishing assertion to make to a biologist, or hy a biolo-
gist ; and such persons have even the temerity to cite such a
special case as that between the wolf and the dog. Many of our
domestic dogs are nothing but wolves, which have been modified
by the hand of man to a very slight extent indeed. Many dogs,
in fact nearly all dogs, are descendants of wild species of various
countries, and are variously modified.

To take the question of the definition of species. Supposing
we have several species well defined, say four or five. In the
process of investigation we obtain a larger number of individuals,
many of which betray characters which invalidate the definitions.
It becomes necessary to unite the four or five species into one.
And so, then, because our system requires that we shall have ac-
curate definitions (the whole basis of the system is definitions ;
you know the very comprehension of the subject requires defini-
tions), we throw them all together, because we can not define all
the various special forms as we did before, until we have but one
species. And the critic of the view of evolution tells us, ^^I told
you so ! There is but one species, after all. There is no such
thing as a connection between species : you never will find it."
Now, how many discoveries of this kind will be necessary to con-
vince the world that there are connections between species ? How
long are we to go on finding connecting links, and putting them
together, as we have to do for the sake of the definition, and then
be told that we have, nevertheless, no intermediate forms between
species ? The matter is too plain for further comment. We
throw them together, simply because our definitions require it.
If we knew all the known individuals which have lived, we should
have no species, we should have no genera. That is all there is
of it. It is simply a question of a universal accretion of material,
and the collection of information. I do not believe that the well-
defined groups will be found to run together, as we call it, in any
one geological period, certainly in no one recent period. We
recognize, however, in looking backward, tliat they converge to
a wonderful extent : one group has diverged at one period, and

THE EXTINCT MAMMALIA. 299

another one has become diversified in a different period ; and so
each one has its history, some beginning farther back than others,
some reaching far back beyond the very beginning of the time
when fossils could be preserved. I call attention to this view be-
cause it is a very easy matter for us to use words for the purpose
of confusing the mind ; for, next to the power of language to ex-
press clear ideas, is its power of expressing no ideas at all. As we
all know, we can say many things which we can not tliink. It is
a very easy thing to say twice two are equal to six, but it is im-
possible to think it.

I would cite what I mean by variations of species in one of its
phases : I mention a genus of snakes, Ophibolus, which is found
in the United States. If we take the species of this snake-genus
as found in the Northern States, we have a good many species well
defined. If we go to the Gulf States, and examine our material,
we see we have certain other species well defined, and they are
very nicely distinguished. If, now, we go to the Pacific coast, to
Arizona and New Mexico, we shall find another set of species
well defined indeed. If we take all these different types of our
specimens of different localities together, our species, as the Ger-
mans say, all tumble together : definitions disappear, and we have
to recognize, out of the preliminary list of thirteen or fourteen,
only four or five. That is simply a case of the kind of fact with
which every biologist is perfectly familiar.

When we come to the history of the extinct forms of life, it is
perfectly true that we can not observe the process of descent in
actual operation, because, forsooth, fossils are necessarily dead.
We can not perceive any activities, because fossils have ceased to
act. But, if this doctrine be true, we should get the series, if
there be such a thing ; and we do, as a matter of fact, find longer
or shorter series of structures, series of organisms proceeding from
one form into another form, which are exactly as they ought to
be if this process of development by descent had taken place.

I am careful to say this ; because it is literally true, as we all
must admit, that species must fall into some kind of order or
other. You could not collect bottles, you could not collect old
shoes, but you could make some kind of a serial order of them.
There are, no doubt, characters by which such and such shoes
could be distinguished from other shoes, these bottles from other
bottles. But if serial order does not prove evolution, as is too
often assumed, we have in recent forms of life in zoology and

PLATE XIII.

THE EXTINCT MAMMALIA. 30I

botany, irrefragable proofs of the metamorphoses, and transfor-
mations, and changes of the species, in accordance with the doc-
trine with which we commenced.

We now come to the second chapter of our subject. With the
assumption, as I take it already satisfactorily proved, of species
having changed into others, in considering this matter of geo-
logical succession or biological succession, I bring you face to face
with the nature and mode of the change ; and hence we may get
a glance perhaps at its laws.

I have on the board a sketch or table which represents the
changes which took place in certain of the Mammalia. I give you
a summary of the kind of thing which we find in one of the
branches of paleontology. I have here two figures, one represent-
ing a restoration, and the other an actual picture, of two extinct
species that belong to the early Eocene periods. One represents
the ancestor of the horse line, Hyracotherium, which has four toes
on his anterior feet, and three behind ; and the other (Plate XIII)
a type of animal, Phenacodus, which is antecedent to all the horse
series, the elephant series, the hog, the rhinoceros, and all the other
series of hoofed animals. It has five toes on all the feet. Each
presents us with the primitive position in which their series first
come to our knowledge in the history of geological time.

I have also arranged here a series of some leading forms of the
three, principal epochs of the Mesozoic times, and six of the lead-
ing ones of the Tertiary time. I have added some dates to show
you the time when the faunae which are entombed in those beds
were discovered, in the course of our studies ; and you will easily
see how unsafe it is to say that any given type of life has never ex-
isted, or even to assert that such and such a form is unknown ;
and it is still more unsafe, I think, to assert that any given form
of life properly defined, or that a specific intermediate form of life,
will not be found. I think it is much safer to assert that such and
such intermediate forms will be found. I have frequently had the
pleasure of realizing anticipations of this kind. I have asserted
that certain types would be found, and they have been found.
You will see that I attend to the matter of time because there have
been a great many things discovered in the last ten or fifteen years
in this department. With these forms I give the date of the dis-
covery of the fauna in which they are embraced.

Here we have the White River fauna discovered in 1856 ; then
we skip a considerable period of time, and the next one was in 1869,

302 THE STRUCTURAL EVIDENCE OF EVOLUTION.

when the Cretaceous series was found. Six or seven Cretaceous
faunae have been discovered. Then we have the Bridger fauna in
1870, the Wasatch fauna in 1874. Next we have, in 1877, the
Equus beds and the fauna which they embrace, part of which was
also found in 1878. The Permian fauna, which is one of the last,
in 1879 ; and the latest, the Puerco, which gives the oldest and
ancestral types of the modern forms of Mammalia, was only found
in 1881. When I first commenced the study of this subject, about
1860, there were perhaps two hundred and fifty species known.
There are now somewhere above 1,000, and we are augmenting
them all the time. I have found many myself : if they were dis-
tributed through the days of the year, I think in some months I
should have had several every day. You see then that the acces-
sions to knowledge which are constantly being made make it un-
safe to indulge in any prophecies ; as, for instance, that, because
such and such things have not been found, therefore they can not
be ; for we find such and such things really have been and really
are discovered.

The successive changes that we have in the Mammalia have
taken place in the limbs, feet, teeth, and brain, and the vertebral
column. The parts which present us with the greatest numbers
of variations are those in which many parts are concerned, as in
the limbs and feet. In the Lower Eocene (Puerco), the toes were
5-5. In the Loup Fork fauna, some possess toes but 1-1. Prior
to this period no such reduction was known, although in the Loup
Fork fauna a very few species remained 5-5. Through this en-
tire series we have transitions steady and constant, from 5-5, to 4-
5, to 4-4, to 4-3, to 3-3, to 2-2, to 1-1. In the Puerco period there
was not a single mammal of any kind which had a good ankle-joint ;
which had an ankle-joint constructed as ankle-joints ought to be,
with tongue and groove. The model ankle-joint is a tongue-and-
groove arrangement. In this period they were nearly all perfectly
flat. As time passes on we get them more and more grooved, un-
til in the Loup Fork fauna and the White Eiver fauna they are near-
ly all grooved. The soles of the feet, in the Puerco fauna, are
all flat ; but in the Loup Fork fauna the soles of the feet are in
the air, and the toes only are applied to the ground, with the excep-
tion of the line of monkeys, in which the feet have not become erect
on the toes, and the elephant, in which the feet are nearly flat also,
and the line of bears, where they are also flat. As regards the
angulation between the small bones of the palm and of the sole,

THE EXTINCT MAMMALIA.

303

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304: THE STRUCTURAL EVIDENCE OF EVOLUTION.

tliere is not a single
instance in which those
bones are locked in the
Lower Eocene, as they
are in the later and
latest Tertiary. So
also with the articula-
tion of the toes with
the foot.

When we come to
the limbs, the species
of the Puerco fauna
have short legs. They
have gradually length-
ened out, and in the
late periods they are
nearly all relatively
long.

Coming to the ver-
tebrae as a part of the
osseous system, I men-
tion the zygapoj^hyses,
or anteroposteriorly
directed processes, of
which the posterior
looks down and the an-
terior looks up. They
move on each other, as
the vertebral column
bends from side to
side. In the lower
forms of vertebrates
they are always flat,
and in the hoofed
mammals of the Puer-
co period they are all
flat. In the Wasatch
period we get a single
group in which the
articulation, instead of
being perfectly flat, be-

THE EXTINCT MAMMALIA.

305

comes rounded ; in the later periods we get them very much
rounded ; and, finally, in the latest forms, we get the double
curve and the locking process in the vertebral column, which,
as in the limb, secures the greatest strength with" the greatest
mobility.

In the first stages of the growth of the spinal column, it is a
notochord, or a cylinder of cartilage or softer material. In later
stages the bony deposit is made in its sheath until it is perfectly
segmented. Now, all the Permian land-animals, reptiles and
batrachians, retain this notochord with the elements of osseous
vertebrae, in a greater or less degree of completeness. There are
some in South Africa, I believe, in which the ossification has come
clear through the notochord ; but they are few. In this charac-
teristic the Permian appears almost, perhaps absolutely, peculiar as

Fig. 61. — Sleeve of a coat showing folds produced by lateral flexure which leaves
interspaces similar to the segments of a rhachitoraous vertebra. Thus, i represents in-
tercentrum ; p^ pleuro-centrum ; and w, neurapophjsis.

regards land-animals. There is something to be said as to the con-
dition of the column from a mechanical standpoint, and it is this :
that the chorda exists, with its osseous elements disposed about it ;
and in the Permian batrachians, equally related to salamanders
and frogs, these osseous elements are arranged in the sheath or
skin of the chorda ; and they are in the form of regular concave
segments, very much like such segments as you can take from the
skin of an orange — but parts of a cylinder, and having greater or
less dimensions according to the group or species. Now, the point
of divergence of these segments is on the side of the column. The
contacts are placed on the side of the column where the segments
separate — the upper segments rising and the lower segments com-
ing downward. To the upper segments are attached the arches
and their articulations, and the lower segments are like the seg-
ments of a cylinder. If you take a flexible cylinder, and cover it
with a more or less inflexible skin or sheath, and bend that cj^linder

306 THE STRUCTURAL EVIDENCE OF EVOLUTION.

sidewise, you of course will find that the wrinkles or fractures of
that part of the surface will take place along the line of the
shortest curve, which is on the side ; and, as a matter of fact, you
have breaks of very much the character of the segments of the Per-
mian Batrachia. It may not be so symmetrical as in the actual
animal, for organic growth is symmetrical so far as not interfered
with ; for, when we have two forces, the one of hereditary growth,
and the other of change or alteration, and they contend, you will
find in the organic being a quite symmetrical result. That is the
universal rule. In the cylinder bending both ways, of course the
shortest line of curve is right at the center of the side of that C3^1-
inder, and the longest curve is of course at the summit and base,
and the shortest curve will be the point of fracture. And that is
exactly what I presume has happened in the case of the construc-
tion of the segments of the sheath of the vertebral column, by the
lateral motion of the animal in swimming, and which has been the
actual cause of the disposition of the osseous material in its form.
I have gone beyond the state of the discussion in calling attention
to one of the forces which have probably produced this kind of
result. That is the state of the vertebral column of many of the
Vertebrata of the Permian period.*

I go back to the Mammalia and call attention to the teeth.
The ordinary tooth of the higher type of the Mammalia, whether
hoofed or not, with some exceptions, is complex with crests or
cusps. By cutting the complex grinding surfaces, we find they
have been derived by the infolding of .extensions of four original
cusps or tubercles. They have been flattened, have been rendered
oblique, have run together, have folded up, have become acute,
have descended deeply, or have lifted themselves, so that we have
teeth of all sorts and kinds, sometimes very elegant, and often-

* Note (Ed. 1886). — Some further elucidation of this point is necessary, since the
fishes have not produced this kind of segmentation by the lateral motions of the
vertebral column in swimming ; at least, such segmentation is not yet known among
them, but rather simple discoidal segmentation. The rhachitomous segmentation
above described would result from a greater flexure than that required for the
propulsion of a fish through the water. This increased flexure was no doubt the
concomitant of the acquisition of a terrestrial mode of life by the early batrachians.
Progression on land by an animal wnth weak limbs requires much greater flexure of
the column than the act of swimming by the use of the caudal part of the body as
in fishes. One can easily convince himself of this by comparing the movements of
a fish in the water with those of a salamander on land. The snakes, where limbs
are wanting, show an even stronger flexure in progression.

THE EXTINCT MAMMALIA. 307

times yery effective in mechanism. In many primary ungulates,
the primitive condition of four conical tubercles is found. In
passing to older periods we find the Mammalia of the Puerco
period, which never have more than three principal tubercles,
with the exception of three or four species. In the succeeding
periods, however, they get the fourth tubercle on the posterior
side. Finally, you get a complicated series of grinding or cutting
apparatus, as the case may be.

Last, but not least, we take the series of the brain. No doubt
the generalization is true, that the primitive forms of Mammalia
had small brains with smooth hemispheres ; later ones had larger
brains with complex hemispheres. In general the Carnivora have
retained a more simple form of brain, while herbivorous animals
have retained a more complicated type of brain. The lowest
forms of Mammalia display the additional peculiarity of having the
middle brain exposed ; and the hemispheres or large lobes of the
brain, which are supposed to be the seat of the mental phenomena,
are so reduced in size at the back end, that you see the middle
brain distinctly, though it is smaller than in reptiles and fishes.
(See Plate XIV. )

It is beyond the possibility of controversy, that these series
have existed, that they have originated in simj^licity and have re-
sulted in complication ; and the further induction must be drawn,
that the process of succession has been toward greater effective-
ness of mechanical work. There are also cases of degradation, as
in the growing deficiency in dentition in man. There is no doubt
that a large number of people are now losing their wisdom-teeth
in both jaws.

We are now brought to the question of the relations which
mind bears to these principles. The question as to the nature of
mind is not so complex as it might seem. There is a great deal
of it, to be sure ; but on examination it resolves itself into a few
ultimate forms. An analysis reduces it to a few principal types or
departments — the departments of the intelligence and of the emo-
tions (with their primary simpler forms, likes and dislikes), and
the will, if such there be. These three groups, proposed by Kant,
are well known, and are adopted by many metaphysicians ; and
they stand the scrutiny of modern science as applied to both men
and the lower animals. But the question of the material of the
mind, the original raw stuff out of which mind was made, is one
which is claiming attention now from biologists, as it always has

PLATE XIV.

Fig. 1.

Fig. 2.

Fig. 3. Fig. 4.

FiGUBEs OF Casts of Bratn-Ciiambers of Extinct MAiiMALiA.

Fig. 1, Periptychus rJiahdodon., cast of roof of brain case, showing middle-brain hemispheres and
part of olfactory lobes, natural size. Original ; from Puerco bed of New Mexico. Fig. 2, Uinta-
therium mirabile^ one third natural size, from Marsh. From Bridger bed of Wyoming. Fig. 3,
Phenacodus primoevvs^ one half natural size. Original ; from Wasatch bed of Wyoming. Fig. 4,
Procamelus occidentalism one half natural size. Original; from Loup Fork bed of New Mexico.
Figs, o, profile ; ft, above ; c, below.

THE EXTINCT MAMMALIA, 309

done from physiologists proper, and physicians. This is sensi-
bility, mere sim2:)le sensibility, unmodified sensation, or con-
sciousness. Sensibility, in connection with memory, is sufficient
for the accomplishment of wonderful results. It is only necessary
to impress the sensibility with the stimuli which this world affords,
whether from the outside or the inside, to have the record made,
and to have the record kept. Among wonderful things this is
perhaps the most wonderful : that a given form of matter should
be able to retain a record of events, a record which is made during
a greater or less degree of sensibility ; which is retained in a state
of insensibility ; and is finally returned to the sensibility by some
curious process of adhesion, as the results of impresses which are
found on the material tissue concerned.

And these simple elements of mind are found in animals. No
zoologist who has perception or honesty, nor any farmer or
breeder, nor any person who has charge of animals in any way,
can deny sensibility to all the lower animals at times. The great
stumbling-block in the way of the thinker in all this field, is the
great evanescence of this sensibility ; the great ease with which
we dissipate it. The readiness with which we can deprive a fel-
low-being of his sense is a stumbling-block in more ways than one.
While it is a question of the greatest difficulty, nevertheless, like
other departments of nature, doubtless it will ultimately be ex-
plained by the researches of physiologists. I only need to call at-
tention to consciousness as an important factor in evolution.

We now approach the question of the origin of organic ma-
chines with fresh resources. Did the consciousness of the animal
find his structure made ready to hand, or did he, under the dire
stimuli of necessity, produce through ages these modifications in
his own structure ? We are told by some of our friends that law
implies a lawgiver, that evolution implies an evolver : the next
question is. Where is the lawgiver ? where is the evolver ? where
are they located ? This question is best answered, as it appears
to me, as follows. In the first place, I may say, it is distinctly
proved in some directions, that the constant applications of force
or motion in the form of strains, in the form of impacts and
blows, upon any given part of the animal organism, do not fail to
produce results in change of structure. I believe the changes in
the ungulates, to which I have called your attention, are the re-
sult of strains and impacts, precisely as I have shown you the
manner of the fracture of the vertebral column of the primitive

310 THE STRUCTURAL EVIDENCE OF EVOLUTION.

vertebrates of the Permian period. This would require long dis-
cussion to render clear ; nevertheless, I venture to make the asser-
tion that this series of structures is the result of definite and dis-
tinct organic forces, directed to special ends. We have yet to get
at the conflicting forces which have produced the results we see.
Mechanical evolution will give us a good deal to do for some time
to come. Of course, if motion has had any effect in modifying
structure, it behooves us to investigate those conditions which
give origin to motion in animals. First in order come the sensi-
bilities of the animal, which we have traced to simple conscious-
ness ; and stimuli, upon notice of which he immediately begins to
move. The primary stimulus of all kinds of motion is necessarily
touch. If a stone falls upon the tail of some animal which has
a tail, he immediately gets out of that vicinity. If a jelly-fish
with a stinging apparatus runs across an eel which has no scales,
the eel promptly moves. External applications of unpleasant
bodies will always cause an animal to chauge his location. Then
he is constantly assaulted by the dire enemy of beasts, hunger, an
instinct which is evidently universal, to judge from the actions of
animals. This seems to have fashioned, in large part, all forms
of life from the least to the greatest, from the most unorganized to
the most complex. Each exercised itself for the purpose of fill-
ing its stomach with protoplasm. Then come the stimuli which
appeal to a sense allied to that of touch, changes of tempera-
ture. No animals like to be too cold or too hot ; and when the
temperature is disagreeable, the tendency is to go away from that
locality. Among primary instincts must be included that of re-
production. After that comes the sensation of resistance, or,
carried to a high degree, of anger : when an animal's interests are
interfered with, its movements restricted, the most energetic dis-
plays are prompted. So, you see, it is a matter of necessity that
mental phenomena lie at the back of evolution, provided always
that the connecting link of the argument — that motion has ever
affected structure — be true. That is a point which, of course,
admits of much discussion. I have placed myself on the affirm-
ative side of that question ; and, if I live long enough, I expect to
see it absolutely demonstrated.

Of course the development of mind becomes possible under
such circumstances. It is not like a man lifting himself up by
his boots, which it would be were there no such thing as memory.
But with that memory which accumulates, which formulates, first

THE EXTINCT MAMMALIA. 311

habits and then structures, especially in the soft, delicate nervous
tissue, the development of the function of the mind, as well as the
machinery of the mind, becomes perfectly possible. We develop
our intellect through the accumulation of exact facts ; through
the collation of pure truth, no matter whether it be a humble
kind of truth — as the knowledge of the changes of the seasons,
which induces some animals to lay up the winter's store ; whether
it be knowledge of the fact that the sting of the bee is very dis-
agreeable ; or knowledge of the fact (of which the wild ox, no
doubt, is thoroughly aware) that the teeth of the wolf are not
pleasant to come in contact with ; or whether it be the complex
knowledge of man. When the cerebral matter has become larger
and more complex, it receives and retains a much greater number
of impressions, and the animal becomes a more highly educated
being.

As regards the department of emotions or passions, they are
also much stimulated by the environment. Animals which live in
a state of constant strife, naturally have their antagonistic passions
much developed ; while amiable, sympathetic sentiments are better
and more largely produced by peace-loving animals. Thus it is
that the various departments of the mind have the beautiful results
which we now find in the human species.

There are some departments of the mind which some of our
friends decline to admit having had such an origin. The moral
faculty, for instance, is excepted by many from this series. But
the reasons why they object to its production in this way are, to
my mind, not valid. The development of the moral faculty, which
is essentially the sense of justice, appears to them not to fall with-
in the scope of a theory of descent or of evolution. It consists of
two parts. First is the sentiment of benevolence, or of sympathy
with mankind, which gives us the desire to treat them as they
should be treated. It is not sufficient for justice that it is un-
mixed mercy or benevolence, which is sometimes very injurious,
and very often misplaced. It requires, in the second place, the
criticism of the judgment, of the mature intellect, of the rational
faculty, to enable the possessor to dispose of his sentiments in the
proper manner. The combination of rational discrimination and
judgment, with benevolence, constitutes the sense of justice, which
has been derived, no doubt, as a summary of the development of
those two departments of the mind — the emotions and the intel-
lect.

312 THE STRUCTURAL EVIDENCE OF EVOLUTION.

It is said that a sense of justice could not be derived from
no sense of justice ; that it could not have been derived from the
state of things which we find in the animals, because no animal is
known to exhibit real justice ; and that objection is valid as far
as it goes. 1 suspect that no animal has been observed to show a
true sense of justice. That they show sympathy and kindness,
there is no question ; but when it comes to real justice, they do
not display it. But do all men display justice ? Do all men
understand justice ? I am very sure not. There are a good many
men in civilized communities, and there are many tribes, who do
not know what justice is. It does not exist as a part of every
mental constitution. I never lived among the Bushmen, and do
not know exactly what their mental constitution is ; but in a gen-
eral way the justice of savages is restricted to the very smallest
possible circle — that of their tribe or of their own family. There
is a class of people who do not understand justice. I do not refer
to people who know what right is, and do not do it ; but to the
primitive state of moral character, in which, as in children, true
justice is unknown. I call attention to the fact, because some
of our friends have been very much afraid that the demonstration
of the law of evolution, physical and metaphysical, would result
in danger to society. I suspect not. The mode in which I under-
stand this question appears to me to be beneficial to society, rather
than injurious ; and I therefore take the liberty of appending this
part of the subject to its more material aspect.

I refer to another topic, that is to the nature of life, and the
physical basis of life. The word '* life " is so complex that it is
necessary to define it, and so to define it away that really the word
"life" does not retain its usual definition. Many phenomena of
life are chemical, physical, mechanical. We have to remove all
these from consideration, because they come within the ordinary
laws of mechanical forces ; but we have a few things left which
are of a different character. One is the law of growth, which is
displayed in the processes of embryonic succession ; secondly, the
wonderful phenomena of sensibility. Those two things we have
not yet reduced to any identity with the ordinary laws of force,
though we know of their dynamic equivalency. In the phenome-
na of embryology the phenomena of evolution are repeated, only
concentrated in the early stages through which animals have to
pass. So whatever explains the general phenomena of evolution
explains the phenomena of embryology.

THE EXXmCT MAMMALIA. 3I3

What is the nature of physical sensibility ? In this planet, it
is found residing only in one form of matter, which has a slightly
varied chemical constitution, namely, protoplasm, so called from
a physical standpoint. Now, this world, as 3'ou all know, has
passed through many changes of temperature. Its early periods,
it is probable, were so very hot that protoplasm had a very poor
chance. Again, can we assume for a moment that this little speck
in the great universe is the only seat of life ? I suppose scarcely
any scientific man will venture to do so. If, therefore, life exists
in other planets, worlds, and systems, does it necessarily occupy
bodies of protoplasm in those different, remote, spheres ? It would
be a great assumption. It is altogether improbable. The cer-
tainty is, that in those planets which are in proximity to the sun's
heat there could be no protoplasm. Protoplasm in the remote
planets would be a hard mineral, and near the sun it would be dis-
sipated into its component gases. So that, if life be found in other
parts of this universe, it must reside in some different kind of
material. It is extremely probable that the physical conditions
that reside in protoplasm might be found in other kinds of matter.
It is in its chemical inertness, and in its physical constitution, that
its adaptation to life resides ; and the physical constitution neces-
sary for the sustentation of life may be well supposed to exist in
matter in other parts of the universe. I only say the door is open
and not closed : any one who asserts that life can not exist in any
other material basis than protoplasm is assuming more than the
world of science will permit him to assume. And that it is con-
fined to this single planet, among the great systems of the universe
— that assumption will not for a moment be allowed. Therefore
the subject is one which allows us a free field for future investiga-
tion : it is by no means closed in the most important laws which
it presents to the rational thinker. I hope, also, if the evi-
dence in favor of this hypothesis of .the creation of living forms
be regarded as true, that no one will find in it any ground for any
very serious modification of existing ideas on the great questions of
right and wrong, which have been long since known by men as a
result of experience, and without any other scientific demonstra-
tion whatsoever.

XI.

ON THE EVOLUTION OF THE VERTEBRATA, PRO-
GRESSIVE AND RETROGRESSIVE.

I. PRELIMINARY.

IisT attempting to ascertain the course of evolution of the
Vertebrata, and to construct phylogenetic diagrams which shall
express this history, among the difficulties arising from deficient
information one is especially prominent. As is well known,
there are many types in all the orders of the Vertebrata which
present us with rudimentary organs, as rudimental digits, feet or
limbs, rudimental fins, teeth, and wings. There is scarcely an
organ or part which is not somewhere in a rudimental and more
or less useless condition. The difficulty which these cases present
is, simply, whether they be persistent primitive conditions, to be
regarded as ancestral types which have survived to the present
time, or whether, on the other hand, they be results of a pi'ocess
of degeneration, and therefore of comparatively modern origin.
The question, in brief, is, whether these creatures presenting
these features be primitive ancestors or degenerate descendants.

In the first place, let us define the meaning of the word degen-
erate. This must be done first from a structural or anatomical
standpoint. Degeneracy may be defined as a loss of parts with-
out corresponding development of other f>ai'ts. All animals are
degenerate in some respect or another, as, for instance, the Mam-
malia in the small size of the pineal gland and of the coracoid
bone ; so that degeneracy, as a whole, can only be affirmed where
the sum of the subtractions is greater than the sum of the addi-
tions. Function of the parts must, however, be consulted in this
matter. We naturally regard sensibility as the highest of animal
functions, and mind as the highest form of sensibility. There-
fore development of organs of sensibility and sense and mind, con-
stitutes a better claim of progress than development of stomach
or of skin. Since motion is under the direction of sensibility,

EVOLrXION OF THE VERTEBRATA. 315

organs of movement have much to do with the question. When
perfection in this respect conflicts with perfection of brain, in
evidence of position, we naturally give the preference to the
latter in deciding. Thus the ruminating mammals are much
superior to man in the structure of their feet, teeth, and stomach,
yet we properly assign the higher position to the Quadrumana and
to man, on account of the superior complication of their brain-
structure.

Paleontology has proved,* what had been already surmised,
that the development of animal organisms has been on lines of
increasing specialization of parts. That is, in lines of increas-
ingly perfect adaptations of structures to ends, or functions. In
certain series of animals we witness steadily increasing perfection
of mechanisms of the limbs for running ; in others for digging ;
in others for flying. In the teeth we find increasing perfection of
machines for grinding, for cutting, or for seizing. In the brain
the specialization has evidently been toward increased acuteness
of perception, increased energy of action, and increased intelli-
gence. Specialization does not, however, necessarily imply pro-
gressive development. Adaptation may be to a parasitic or a ses-
sile mode of life. Such adaptation is often displayed in a very
special modification of parts, as in the anterior limbs of some of
the parasitic Crustacea ; in the mouth parts of some Arachnida ;
in the feet of the sloth, and in the jaws of the ant-eaters.

Embryology has furnished, and will furnish, many important
hints and demonstrations as to the true meaning of the rudiment-
ary condition or absence of parts, and thus indicate the phylo-
genetic connections of animals. Thus the origin of the Tunicata
from primitive vertebrate-like forms would probably never have
been suspected but for embryological studies ; and the origin of
the very peculiar order of Eotifera has been explained in like
manner. But embryology has its limitations, for the transitional
characters presented by embryos are only partially of the nature
of a record of the structures which belonged to their ancestors in
successive geological ages, and are frequently special adaptations
to the necessities of their embryonic life. Such are the stato-
blasts which are present in fresh-water sponges and Polyzoa, and
wanting in the marine forms ; and the allantois and placenta of

* Cfr. " On the Evidence for Evolution in the History of the Extinct Mam-
malia," "Proc. Amer. Assoc. Adv. Sciences" for 1883.

316 THE STRUCTURAL EVIDENCE OF EVOLUTION.

Vertebrata. In a number of groups the embrj^o seems to have
been more susceptible to the influence of the environment than
the adults.* It results that in many cases the phylogeny can
only be determined by the discovery and investigation of the
ancestors themselves, as they are preserved in the crust of the
earth. In all cases this discovery confirms and establishes such
definite conclusions as may be derived from embryology. It is
also clear that on the discovery of phylogenetic series it becomes
at once possible to determine the nature of defective types. It
becomes possible to ascertain whether their rudimental parts
represent the beginnings of organs, or whether they are the
.result of a process of degeneration of organs once well develoj^ed.
A great deal of light has been happily thrown on this question,
as regards the Vertebrata, by the recent work done in North
American paleontology. The lines of descent of many of the
minor groups have been positively determined, and the phyloge-
netic connections of most of the primary divisions or classes have
been made out. The result of these investigations has been to

* A remarkable instance of this state of things appears in the history of the
evolution of the insects. It is quite impossible to understand this history without
believing that the larval and pupal states of the highest insects are the results of a
process of degeneracy which has affected the middle periods of growth but not the
mature results. The earliest insects are the Orthoptera, which have active aggres-
sive larvae and pupae, undergoing the least changes in their metamorphosis (Ameta-
bola), and never getting beyond the primitive mandibulate condition at the end.
The metamorphosis of the jawed Neuroptera is little more marked, and they are
one of the oldest orders.

The highest orders with jaws undergo a marked metamorphosis (Coleoptera,
Hymenoptera), the Hymenoptera even requiring artificial intervention in some in-
stances to make it successful. Finally, the most specialized orders, the suctorial
Diptera and Lepidoptera, especially the latter, present us with very unprotected
more or less parasitic stages, both active and inactive. These animals have
evidently degenerated, but not so as to prevent their completing a metamorphosis
necessary for purposes of reproduction. As is well known, many imagines (Satur-
niidae, (Estridae) can perform no other function, and soon die, while in some Diptera
the incomplete larvae themselves reproduce, so that the metamorphosis is never
completed.

This history is parallel to that proposed by Dohrn to account for the origin of
the Amraocoetes larval stage of the Marsipobranchii. He supposes this form to be
more degenerate than its probable ancestral type in the ancestral line of the Verte-
brata, as it is inferior to its own adult. An inactive life in mud is supposed by
Dohrn to have been the effective cause. An inactive life on the leaves of plants,
or in dead carcases, has probably been the cause of the same phenomenon in the
Lepidoptera and Diptera.

EVOLUTION OF THE VERTEBRATA. 317

prove that the evolution of the Vertebrata has proceeded not only
on lines of acceleration, but, to a much greater extent than has
been heretofore suspected, on lines of retardation.* That is, that
evolution has been not only progressive, but at times retrogressive.
This is entirely in accord with the views derived by Dohrn from
embryology,! who, however, wrote only of the origin of the
Vertebrata as a whole and not of its divisions, excepting only
the Leptocardii and Marsipobranchii, that is, of the sand-lance
and the lampreys and hags. The demonstration of such relations
for the higher Vertebrata is now done nearly for the first time. J

Omitting from consideration the two classes above mentioned,
whose remains have not yet been certainly found in a fossil state,
there remain the following : the Pisces, Batrachia, Eeptilia, Aves,
and Mammalia.

The Mammalia have been traced to the theromorphous reptiles
through the Monotremata. The birds, some of them at least, ap-
pear to have been derived from the Dinosaurian reptiles. The rep-
tiles, in their primary representative order, the Theromorpha, have
been probably derived from the rhachitomous Batrachia.* The
Batrachia have originated from the subclass of fishes, the Dipnoi,
though not from any known form. I have shown that the true
fishes or Teleostomi have descended from an order of sharks, ||
the Ichthyotomi, which possess characters of the Dipnoi also.
The origin of the sharks remains entirely obscure, as does also
that of the Pisces as a whole. Dohrn believes the Marsii^o-

* See "Origin of Genera," E. D. Cope, Philadelphia, 1868, where these terms
are introduced.

f See "Der Ursprung der Wirbelthiere u. d. Princip des Functionwechsels,"
Leipsic, 18'75.

^ "On the Phylogeny of the Vertebrata," Cope, " Amer. Naturalist," Dec., 1884.
I here remark that my researches have now, as I believe, disclosed the ancestry of
the mammals, the birds, the reptiles, and the true fishes, or Teleostomi, including
the special phylogenies of the Batrachia and Reptilia, and some of the Mammalia.
See the following references: "American Naturalist," 1884, p. 1136 ; "Proceedings
Academy Philadelphia," 186Y, p. 234; "Proceedings American Philosoph. Society,"
1884, p. 585; "American Naturalist," 1884, p. 27; "Proceedings American Asso-
ciation for the Advancement of Science," xix, ISTl, p. 233; "Proceedings Amer-
ican Philosophical Society," 1882, p. 447; "American Naturalist," 1884, pp. 261
and 1121 ; "Report U. S. Geol. Survey W. of lOOth Mer.," G. M. Wheeler, 1877,
iv, ii, p. 282.

* Through the batrachian order Embolomeri. (Ed. 1886.)
I "Proceedings Am. Phil. Soc," 1884, p. 585.

318 THE STRUCTURAL EVIDENCE OF EVOLUTIOi^.

branchii to have acquired its present characters by a process of
degeneration. The origin of the Vertebrata is as yet entirely un-
known, Kowalevsky deriving them from the Ascidians, and
Semper from the Annelida. The above results I have embodied
in the following phylogenetic diagram :

Aves Mammalia

\ /

Reptilia

/
/

[ Teleostomi* Batrachia

I I ^ ■

Pisces \ Selachii Ichthjotorai Dipnoi

Holocephali
Leptocardii

Marsipobranchi

Accepting this phylogeny, it becomes possible to determine
the course of development, first, of the whole series ; and, secondly,
of the contents of each class taken by itself. I will first consider
the direction of the evolution of the Vertebrata as a whole.

IT. THE VERTEBRATE LINE.

The Vertebrata exhibit the most unmistakable gradation in
the characters of the circulatory system, f It has long been the
custom to define the classes by means of these characters, taken
in connection with those of the skeleton. Commencing in the
Leptocardii with the simple tube, we have two chambers in the
Marsipobranchii and fishes ; three in the Batrachia and Reptilia ;
and four in the Aves and Mammalia. The aorta-roots commence
as numerous pairs of branchial arteries in the Leptocardii ; we
see seven in the Marsipobranchi, five in the fishes (with number
reduced in some) ; four and three in Batrachia, where they gener-
ally cease to perform branchial functions ; two and one on each
side in Reptilia ; the right-hand one in birds, and the left-hand
one in Mammalia. This order is clearly an ascending one through-
out. It consists of, first, a transition from adaptation to an aquatic,
to an aerial respiration ; and, second, an increase in the power to
aerate and distribute a circulating fluid of increased quantity,

* In the original I used the name Hyopomata for this division, but Owen's name
Teleostomi is prior. (Ed. 1886.)

+ See *' Origin of Genera/' 1868, p. 20, for a table of the characters of the circu-
latory system.

EVOLUTION OF THE YERTEBRATA. 319

and of increased calorific capacity. In other words, the circula-
tion passes from the cold to the hot blooded type coincidentally
with the changes of structure above enumerated. The accession
of a capacity to maintain a fixed temperature while that of the
surrounding medium changes, is an important advance in animal
economy.

The brain and nervous system also display a general progress-
ive ascent. Leaving the brainless Leptocardii, the Marsipo-
branchs and fishes present us with small hemispheres, larger
optic lobes, and well-developed cerebellum. The hemispheres
are really larger than they appear to be, as Rabl Riickard has
shown * that the supposed hemispheres are only corpora striata.
But the superior walls are membranous, and sujoport on their in-
ternal side only a layer of epithelial cells, as in the embryos of
other Vertebrata, instead of the gray substance. So that, al-
though we find that the cerebellum is really smaller in the
Batrachia and most Eeptilia than in the fishes, the better de-
velopment of the hemispheres in the former gives them the pre-
eminence. The Elasmobranchii show themselves superior to
many of the fishes in the large size of their corpora restiformia
and cerebellum. The Eeptilia constitute an advance on the Ba-
trachia. In the latter the optic thalami are, with some excep-
tions, of greater diameter than the hemispheres, while the reverse
is generally true of the reptiles. The crocodiles display much
superiority over the other reptiles in the larger cerebellum, with
rudimental lateral lobes. The great development of the hemi-
spheres in birds is well known, while the general superiority of
the brain of the living Mammalia over all other vertebrates is
admitted.

The consideration of the successive relations of the skeleton in
the classes of vertebrates embraces, of course, only the characters
which distinguish those classes. These are not numerous. They
embrace the structure of the axis of the skull ; of the ear-bones ;
of the suspensors of the lower jaw ; of the scapular arch and
anterior limb, and of the pelvic arch and posterior limb. Other
characters are numerous, but do not enter into consideration at
this time.

The persistence of the primitive cartilage in any part of the
skeleton is, embryologically speaking, a mark of inferiority.

* n

Biologisches Centralblatt," 1884, p. 449.

320 THE STRUCTURAL EVIDENCE OF EVOLUTION.

From a physiological or functional standpoint it has the same
significance, since it is far less effective both for support and for
movement than is the segmented osseous skeleton. That this is
a prevalent condition of the lower Vertebrata is well known.
The bony fishes and Batrachia have but little of the primitive
cartilage remaining, and the quantity is still more reduced in the
higher classes. Systematically, then, the vertebrate series is in
this respect an ascending one. The Leptocardii are membra-
nous ; the Marsipobranchii and most of the Elasmobranchii
cartihiginous ; the other Pisces and the Batrachia have tlie
basicranial axis cartilaginous, so that it is not until the Eeptilia
are reached that we have osseous sphenoid and presphenoid bones,
such as characterize the birds and mammals. The vertebral
column follows more or less inexactly the history of the base of
the skull, but its characters do not define the classes.

As regards the suspensor of the lower jaw, the scale is in the
main ascending. We witness a gradual change in the segmenta-
tion of the mandibular visceral arch of the skull, which clearly
has for its object such a concentration of the parts as will produce
the greatest effectiveness of the biting function. This is accom-
plished by reducing the number of the segments, so as to bring
the resistance of the teeth nearer and nearer to the power, that is,
the masse ter and related muscles, and their base of attachment,
the brain-case. This is seen in bony Vertebrates in the reduction
of the segments between the lower jaw proper and the skull, from
four to none. In the fishes we have the hyomandibular, the sym-
plectic, the inferior quadrate, and the articular. In the Ba-
trachia, reptiles and birds, we have the quadrate and articular
only, while in the Mammalia these elements also are wanting.

The examination of the pectoral and pelvic arches reveals a
successive modification of the adaptation of the parts to the me-
chanical needs of the limbs. In this regard the air-breathing
types display wide diversity from the gill-bearing types or fishes.
In the latter, the lateral elements unite below without the inter-
vention of a median element or sternum, while in the former the
sternum, or parts of it, is generally present. Either arrange-
ment is susceptible of much mechanical strength, as witness the
Siluroid fishes on the one hand, and the mole on the other. The
numerous segments of the fishes' pectoral arch must, however, be
an element of weakness, so that from a mechanical standpoint it
must take the lowest place. The presence of sternal elements,

EVOLUTION OF THE VERTEBRATA. 321

with both clavicle, procoracoid, and coracoid bones on each side,
gives the Reptilia the highest place for mechanical strength. The
loss of the coracoid seen in the tailed Batrachia, and loss of cora-
coid and procoracoid in the Mammalia, constitute an element of
weakness. The line is not then one of uniform ascent in this re-
spect.

The absence of pelvis, or its extremely rudimental condition in
fishes, places them at the foot of the line in this respect. The
forward extension of the ilium in some Batrachia and in the Mam-
malia, is to be compared with its backward direction in Reptilia,
and its extension both ways in the birds. These conditions are
all derived by descent from a strictly intermediate position in the
Batrachia and Reptilia of the Permian epoch. The anterior di-
rection must be regarded as having the mechanical advantage
over the posterior direction, since it shortens the vertebral column
and brings the posterior nearer to the anterior feet. The prev-
alence of the latter condition in the Mammalia enables them to
stand clear of the ground, while the Reptilia move with the abdo-
men resting upon it. As regards the inferior arches of the pelvis,
the Mammalia have the advantage again, in the strong bony me-
dian symphysis connecting the ischium and pubis.* This char-
acter, universal among the land Vertebrata of the Permian epoch,
has been lost by the modern Reptilia, and birds, and is retained
only by the Mammalia. So the lines, excepting the mammalian,
have degenerated in every direction in the characters of the pelvis.

The limbs of the Pisces are as well adapted to their environ-
ment as are those of the land Vertebrata ; but, from an embryolog-
ical standpoint, their structure is inferior. The primitive raj^s
are less modified in the fin than in the limb ; and limbs them-
selves display a constantly increasing differentiation of parts, com-
mencing with the Batrachia and ending with the Mammalia.
The details of these modifications belong to the history of the
contents of the classes, however, rather than to the succession of
the Vertebrata as a whole.

In review, it may be said that a comparison of the characters
which define the classes of the Vertebrates shows that this branch
of the animal kingdom has made with the ages successive steps
of progress from lower to higher conditions. This progress has
not been without exception, since, as regards the construction of

* This is an advantage as a protection during gestation.
21

322 THE STRUCTURAL EVIDENCE OF EVOLUTIOK

the scapular arch, the Mammalia have retrograded from the rep-
tilian standard as a Avhole.

In subsequent pages I shall take up the lines of the classes
separately.

III. THE LliTE OF THE UKOCHOKDA.

Embryological evidence leads us to anticipate that the primi-
tive Vertebrata possessed nothing representative of the vertebrate
skeleton beyond a chorda dorsalis. Above this axis should lie the
nervous chord, and below it the nutritive and reproductive sys-
tems and their appendages. Such a type we have in its simplest
form in the Branchiostoma, the representative of the division of
the Acrania. In the animals of this division the mouth and anus
have the usual vertebrate jDosition, at opposite ends of the body-
cavity. The Tunicata (formerly referred to the Mollusca) are now
known to present a still more primitive type of Vertebrata, to
which the name of Urochorda has been given. These curious,
frequently sessile creatures, have a vertebrate structure during the
larval stage, which they ultimately lose. They have the necessary
chorda, and nervous axis with a brain, and a cerebral eye. They
have at this time a tail> and are free-swimming ; a peculiarity
which a few of them retain throughout life (Appendicularia).*
They differ from the Acrania in the positions of the extremities
of the alimentary canal. The mouth is on the top of the anterior
end of the animal, and is supposed by some anatomists to repre-
sent an open extremity of the pineal gland of other Vertebrata ;
while the tract represented by this body, the third ventricle of the
brain, and the pituitary body of the Craniata, are the remains of
the primitive oesophagus of the Urochorda. The anus in the
adult tunicates is either dorsal, or it opens into the body-cavity, as
in the young larvas. In Appendicularia it is ventral (Gegenbaur).

The history of the Tunicata can not be traced by paleontolo-
gists as yet, owing to the absence of hard parts in their structure.
The evidence of embryology has, however, convinced phylogenists
that the ancestors of this class resembled their larvae, and that they
have as a whole undergone a remarkable degeneracy. They have
passed from an active, free life to a sessile one, and have lost the
characters which pertain to the life of vertebrates generally.

It was to have been anticipated, however, that all of these an-

* See Lankester on "Degeneration," " Nature Series," 1880.

EVOLUTION OF THE VERTEBRATA.

323

cestral Tunicata did not undergo this degenerative metamorphosis
for it is to such types that we must look for the ancestors of the
other Vertebrata, the Acrania and the Craniata. And here pale-
ontology steps in and throws new light on the question. I have
pointed out briefly, in the " American Naturalist/' * that a second
order must be added to the Urochorda, viz., the Antiarcha, in
which the anus presents the same position as in the Acrania, at
the posterior end of the body, while an orifice of the upper surface
represents the mouth of the Tunicata. To this order is to be re-
ferred the family of the Pterichthyidag, of which the typical genus,

Fig. 63.

Fig. 62.

Fig. 62. Bothriolepis canadensis Whiteaves, from above, half size of a small speci-
men. The valve of the dorsal mouth, or notostome, is broken. Fig. 63. Chelyosoma
maclomanum Brod. & Sow., Y3 natural size, from Point Barrow, Alaska.

Pterichthys, is a well-known form of the Devonian period. This
genus retained its tail, which was the cause, in connection with
the i^resence of lateral fin-like appendages, of its having been sup-
posed to be a fish, by Agassiz, Hugh Miller, and others. It is pos-
sible that the American Bothriolepis canadensis lost its tail, as in
the majority of Urochorda. The tunicate which approaches near-
est to the Antiarcha is the Arctic Chelyosoma.

From the Antiarcha to the Acrania and Craniata, then, the
line is an ascending one.

* March, 1885, p. 289.

324: THE STRUCTURAL EVIDENCE OF EVOLUTION.

lY. THE LIl^E OF THE PISCES.

The fishes form various series and subseries, and the tracing
of all of them is not yet practicable, owing to the deficiency in
our knowledge of the earliest or ancestral forms. Thus the ori-
gins of the four subclasses, Holocephali, Dipnoi, Elasmobranchii,
and Teleostomi, are lost in the obscurity of the early Palaeozoic
ages.

A comparison of the four subclasses just named shows that
they are related in pairs. The Holocephali and Dipnoi haye no
distinct suspensory segment for the lower jaw, while the Elasmo-
branchii and Hyopomata have such a separate element. The lat-
ter, therefore, present one step in the direction of complication be-
yond the former ; but whether the one type is descended from the
other, or whether both came from a common ancestor or not, is
unknown. If one type be derived from the other, it is not certain
which is ancestor, and whether the process has been one of advance
or retrogression. The fauna of the Permian epoch throws some
light on the relations of these subclasses in other respects. The
order of the Ichthyotomi,* while belonging technically to the
Elasmobranchi, presents characters of both the Dipnoi and the
Teleostomi. It is so near to the Dipnoi in the characters of the
skull that nothing save the presence of a free suspensor of the
lower jaw prevents its entering that subclass. It indicates that
the one of these divisions is descended from the other, or both
from a common division which may well be the group Ichthyotomi
itself. In case the Elasmobranchi have descended from the Ich-
thyotomi, they have undergone degeneracy, as the Ichthyotomi
have a higher degree of ossification and differentiation of the bones
of the skull. If they descended from a purely cartilaginous type
of Dipnoi, they have advanced, in the addition of the free hyo-
mandibular. If the Dipnoi have descended from either division,
they have retrograded, in the loss of the free hyomandibular. As
regards the Teleostomi, we have a clear advance over the other
subclasses in the presence of the maxillary arch and the opercular
apparatus.

Too little is known of the history of the subclasses, excepting
the Teleostomi, for us to be able to say much of the direction of

* See " Palseontological Bulletin," No. 38, E. D. Cope, 18S4, p. 512, on the genus
Didvmodus.

EVOLUTION OF THE VERTEBRATA. 325

the descent of their contained orders. On the sharks some light
is shed by the discovery of tlie genus Chlamydoselachus Garman,*
which is apparently nearly related to the Cladodonts of the Devo-
nian seas. This genus has more numerous branchial slits than all
but two of the genera of existing sharks, and it differs from all but
these two in having a more perfect articulation between the tooth-
bearing bones and the cranium. Of the Teleostomi a much clearer
history is accessible. It has three primary divisions or tribes which
differ solely in the structure of the supports of the fins. In the
first division, the Crossopterygia, the anterior limbs have numerous
basilar bones which are supported on a peduncle of axial bones.
The posterior limbs are similar. In the second division, or Chron-
drostei (the sturgeons, etc. ), the posterior limb remains the same,
while the anterior limbs have undergone a great abbreviation in
the loss of the axial bones and the reduction of the number and
length of the basilar bones. In the third group, or Actinopteri,t
both limbs have undergone reduction, the basilar bones in the pos-
terior fin being almost all atrophied, while those of the fore limb
are much reduced in number.

The phylogeny of these tribes is not easy to make out at pres-
ent. The descent has been, no doubt, in the order named in time,
but the starting-point is yet uncertain. Thus the Chondrostei
appear later in time than either of the other tribes, a history
which probably only represents our ignorance. The characters of
the genus Crossopholis Cope, from the American Eocene, strongly
suggest that the existing forms have descended from scaled an-
cestors. The Crossopterygian fore limb, with its arm-like axis,
tells of the origin of the first limbed vertebrates, the Batrachia,
whose skull-structure, however, only permits their derivation
from the Dipnoi or Ilolocephali. As the former subclass has the
Crossopterygian fin-structure, we can safely regard them as the
ancestors of the Batrachia, while the Crossopterygia are a side-
line from a similar type, probably the Ichthyotomi, because these
have a free suspensor of the lower jaw. But of the structure of
the fins of the Ichthyotomi unfortunately we know nothing. If
this position be true, then the successive derivation of the Chon-
drostei and the Teleostomi in one line is rendered probable. The
modification of structure has consisted in the contraction of the

* "Proceedings American Assoc. Adv. Sci.," 1884.

f Partly agrees with the Teleostei of Miiller, but includes many of his Ganoidea.

326 THE STRUCTUKAL EVIDENCE OF EYOLUTION.

supporting elements of the pectoral and ventral fins by the reduc-
tion of their numbers and length. According to paleontological
history, however, the tribe of Teleostomi with most contracted
fins, Actinopteri, appeared in the Coal Measures (Paleoniscidse),
or very soon after the Crossopterygia in the Devonian.

The descent of the fishes in general has witnessed, then, a
contraction of the limbs to a very small compass, and their sub-
stitution by a system of accessory radii. This has been an ever-
widening divergence from the type of the higher Vertebrata, and
from this standpoint, and also a view of the ^Hoss of parts with-
out complementary addition of other parts," may be regarded as
a process of degradation.

Taking up the great division of the Actinopteri, which em-
braces most of the species of living fishes, we can trace the direc-
tion of descent largely by reference to their systematic relations
when we have no fossils to guide us.

The three sub tribes adopted by Jordan represent three series
of the true fishes which indicate lines of descent. The Holostei
include the remainder of the old ganoids after the subtraction of
the Crossopterygia and the Chondrostei. They resemble these
forms in the muscular bulbus arteriosus of the heart and in the
chiasm of the optic nerves. Both of these characters are com-
plexities which the two other divisions do not possess, and which,
as descendants coming later in time, must be regarded as inferior,
and therefore to that extent degenerate. Of these divisions the
Physostomi approach nearest the Holostei, and are indeed not
distinctly definable without exceptions. The third division, or
Physoclysti, shows a marked advance beyond the others in : (1)
the obliteration of the primitive trachea, or ductus pneumaticus,
which connects the swim-bladder and oesophagus ; (2) the advance
of the ventral fins from the abdomen forward to the throat ; (3)
the separation of the parietal bones by the supraoccipital ; (4)
the presence of numerous spinous rays in the fins ; and (5) the
roughening of the edges of the scales, forming the ctenoid type.
There are more or less numerous exceptions to all of these char-
acters. The changes are all further divergencies from the other
vertebrate classes, or away from the general line of ascent of the
vertebrate series taken as a whole. The end gained is specializa-
tion ; but whether the series can be called either distinctively pro-
gressive or retrogressive, is not so clear. The development of
osseous spines, rough scales, and other weai)ons of defense, together

EVOLUTION" OF THE YERTEBRATA. 327

with the generally superior energy and tone which prevail among
the Physoclysti, characterize them as superior to the Physostomi,
but their departure from the ascending line of the Vertebrata has
another appearance.

The descent of the Physoclystous fishes has probably been
from Ilolostean ancestors, both with and without the intervention
of Physostomous forms. This is indicated by increase in the
number of basilar bones in the fins of families which have pec-
toral ventral fins, as in the extinct genus Dorypterus.*

The Physostomi display three or four distinct lines of descent.
The simplest type is represented by the order Isospondyli, and
paleontology indicates clearly that this order is also the oldest,
as it dates from the Trias at least. In one line the anterior dor-
sal vertebrae have become comjolicated, and form an interlocking
mass which is intimately connected with the sense of hearing.
This series commences with the Characinidae, passes through the
Cyprinidae, and ends with the Siluridae. The arrangements for
audition constitute a superadded complication, and to these are
added in the Siluroids defensive spines and armor. Some of
this order, however, are distinctly degenerate, as the soft pur-
blind Ageniosus, and the parasitic Stegophilus and Vandellia,
which are nearly blind, without weapons, and with greatly re-
duced fins.

The next line (the Haplomi, pike, etc.) loses the precoracoid
arch and has the parietal bones separated, both characters of the
Physoclysti. This group was apparently abundant during the
Cretaceous period, and it may have given origin to many of the
Physoclysti.

Another line also loses the precoracoid, but in other respects
diverges totally from the Physoclysti and all other Physostomi.
This is the line of the eels. They next lose the connection be-
tween the scapular arch and the skull, which is followed by the
loss of the pectoral fin. The ventral fin disappeared sooner. The
palatine bones and teeth disappear, and the suspensor of the lower
jaw grows longer and loses its symplectic element. The opercu-
lar bones grow smaller, and some of them disappear. The ossi-
fication of most of the hyoid elements disappears, and some of
their cartilaginous bases even vanish. These forms are the marine
eels or Colocephali. The most extraordinary example of speciali-

* See " Proceeds. Amer. Assoc. Adv. Science," 1 SVS, p. 297.

328 THE STRUCTURAL EVIDENCE OF EVOLUTION'.

zation and degeneracy is seen in the abyssal eels of the family
Eurypharyngidge. Here all the degenerate features above men-
tioned are present in excess, and others are added, as the loss of
ossification of a part of the skull, almost total obliteration of the
hyoid and scapular arches, and the semi-Dotochordal condition of
the vertebral column, etc.

The Physoclysti nearest the Physostomi have abdominal ven-
tral fins, and belong to several orders. It is such types as these
that may be supposed to have been derived directly from Holos-
tean ancestors. They appear in the Cretaceous period (Derceti-
dae), along with the types that connect with the Physostomi
(Haplomi). Intermediate forms between these and typical Phy-
soclysti occur in the Eocene (Trichophanes, Erismatopterus),
showing several lines of descent. The Dercetidse belong appar-
ently to the order Hemibranchi, while the Eocene genera named
belong apparently to the Aphododiridse, the immediate ancestor
of the highest Physoclysti, the Percomorphi. The order Hemi-
branchi is a series of much interest. Its members lose the mem-
brane of their dorsal spinous fin (Gasterosteidse), and then the fin
itself (Fistularia, Pegasus). The branchial apparatus has under-
gone, as in the eels, successive deossification (by retardation), and
this in direct relation to the degree with which the body comes
to be protected by bony shields, reaching the greatest defect in
the Amphisilidas. One more downward step is seen in the next
succeeding order of the Lophobranchii. The branchial hyoid
ap23aratus is reduced to a few cartilaginous pieces, and the bran-
chial fringes are much reduced in size. In the Hippocampidae
the caudal fin disappears and the tail becomes a prehensile organ
by the aid of which the species lead a sedentary life. The mouth
is much contracted and becomes the anterior orifice of a suctorial
tube. This is a second line of unmistakable degeneracy among
true fishes.

The Physoclysti with pectoral ventral fins present us with per-
haps ten important ordinal or subordinal divisions. Until the
paleontology of this series is better known, we shall have diffi-
culty in constructing phylogenies. Some of the lines may, how-
ever, be made out. The accompanying diagram will assist in un-
derstanding them.

The Anacanthini present a general weakening of the organiza-
tion in the less firmness of the osseous tissue and the frequent
reduction in the size and character of the fins. The caudal ver-

EVOLUTION OF THE VERTEBRATA. 329

tebrae are of the protocercal type. As tliis group does not appear
early in geological time, and as it is largely represented now in
the abyssal ocean fauna, there is every reason to regard it as a
degenerate type.* The
scyphobranch line presents
a specialization of the su-
perior pharyngeal bones,
which is continued by the
Haplodoci (Batrachid^e).
This can not be called a
degenerate line, although
the fin-ravs are soft. The
Heterosomata (flounders)
found it convenient to lie
on one side, a habit which
would appear to result
from a want of motive en-
ergy. The fins are very
inefficient organs of move-
ment in them, and they
are certainly no rivals for
swift-swimming fishes in
the struggle for existence,
excepting as they conceal
themselves. In order to

see the better while un- S 'S § \^ 13 "S

seen, the inferior eve has -^ S ^ '^ c .2

turned inward, i. e., up- | J ^ A' I 2 ^

ward, and finally has pen- ''^ "~^

etrated to the superior
surface, so that both eyes
are on one side. This pe-
culiarity would be incred-
ible if we did not know
of its existence, and is an
illustration of the extraordinary powers of accommodation pos-

* The general characters of the deep-sea fish-fauna are those of degeneracy.
(Ed. 1886.)

f This order was proposed by Gill for the Eurypharyngidae, and is now added,
(Ed. 1886.)

330 THE STRUCTURAL EVIDENCE OF EVOLUTION".

sessed by nature. ThQ Heterosomata can only be considered a
degenerate group.

The double bony floor of the skull of the Distegous percomorph
fishes is a complication which places them at the summit of the
line of true fishes. At the summit of this division must be placed
the Pharyngognathi, which fill an important role in the economy
of the tropical seas, and the fresh waters of the Southern hemi-
sphere. By means of their powerful grinding pharyngeal appara-
tus they can reduce yege table and animal food inaccessible to other
fishes. The result is seen in their multifarious species and innu-
merable individuals decked in gorgeous colors, and often reaching
considerable size. This is the royal order of fishes, and there is no
reason why they should not continue to increase in importance in
the present fauna.

Very different is the line of the Plectognathi. The probable
ancestors of this division, the Epilasmia (ChaetodontidaB, etc.), are
also abundant in the tropical seas, and are among the most brill-
iantly colored of fishes. One of their peculiarities is seen in a
shortening of the brain-case and prolongation of the jaws down-
ward and forward. The utility of this arrangement is probably to
enable them to procure their food from the holes and cavities of
the coral reefs among which they dwell. In some of the genera
the muzzle has become tubular (Chelmo), and is actually used as
a blow-gun by which insects are secured by shooting them with
drops of water. This shortening of the basicranial axis has pro-
duced a corresponding abbreviation of the hyoid apparatus. The
superior piharyngeal bones are so crowded as to have become a
series of vertical plates like the leaves of a book. These charac-
ters are further developed in the Plectognathi. The brain-case is
very small, the face is very elongate, and the mouth is much con-
tracted. The bones surrounding it in each jaw are co-ossified.
The axial elements (femora) of the posterior fins unite together,
become very elongate, and lose the natatory portion. In one group
(Orthagoriscidae) the posterior part of the vertebral column is lost
and the caudal fin is a nearly useless rudiment. In the Ostracion-
tidae (which may have had a different origin, as the pharyngeal
bones are not contracted) the natatory powers are much reduced,
and the body is inclosed in an osseous carapace so as to be capable
of very little movement. The entire order is deficient in osseous
tissue, the bones being thin and weak. It is a marked case of
degeneracy.

EVOLUTION OF THE VERTEBRATA. 331

There are several evident instances of sporadic degeneracy in
other orders. One of these is the case of the family of the Icos-
teidse, fishes from deep waters off the coast of California. Al-
though members of the Percomorphi, the skeleton in the two gen-
era Icosteus and Icichthys is unossified, and is perfectly flexible.
Approximations to this state of things are seen in the parasitic
genus Cyclopterus, and in the ribbon-fishes, Trachypteridee.

Thus nearly all the main lines of the Physoclysti are degener-
ate ; the exceptions are those that terminate in the Scombridse
(mackerel), Serranidae, and Scaridae (Pharyngognathi).

Y. THE LIKE OF THE BATRACHIA.

We know Batrachia first in the Coal Measures. They reach a
great development in the Permian epoch, and are represented by
large species in the Triassic period. From that time they dimin-
ish in numbers, and at the present day form an insignificant part
of the vertebrate fauna of the earth. The history of their suc-
cession is told by a table of classification such as I give below :

I. Supraoccipital, intercalary and supratemporal bones present. Propodial

bones distinct.

Vertebral centra, including atlas, segmented, one set of segments together support-
ing one arch Rhachitomi.

Vertebrae segmented, the superior and inferior segments each complete, forming two
centra to each arch EmbolomeH.

Vertebral centra, including atlas, not segmented, one to each arch StegoccpJiali.

II. Supraoccipital and supratemporal bones wanting. Frontal and propodial

bones distinct.

a. An OS intercalare,

A palatine arch and separate caudal vertebrae Proteida.

aa. No OS intercalare.
A maxillary arch ; palatine arch imperfect ; nasals, premaxillaries and caudal verte-
brae distinct Urodela*

No maxillary or palatine arches ; nasals and premaxillary, also caudal vertebrae, dis-
tinct Trachystomata,

III. Supraoccipital, intercalare and supratemporal bones wanting. Frontals
and parietals connate ; propodial bones and caudal vertebrae confluent.

Premaxillaries distinct from nasals ; no palatine arch ; astragalus and calcaneum
elongate, forming a distinct segment of the limb Anura.

The probable phylogeny of these orders as imperfectly indi-
cated by paleontology is as follows :

Probably includes the Gymnophiona.

332 THE STRUCTURAL EVIDENCE OF EVOLUTION".

Anura

Urodela Trachjstomata *

I
Proteida

Stegocephali

I.
Embolomeri Rhachitomif

Ganocephala J

An examination of the above tables shows that there has been
in the history of the Batrachian class a reduction in the number
of the elements composing the skull, both by loss and by fusion
with each other. It also shows that the vertebrae have passed from
a notochordal state with segmented centra, to biconcave centra,
and finally to ball-and-socket centra, with a great reduction of the
caudal* series. It is also the fact that the earlier forms (those of
the Permian epoch) show the most Mammalian characters of the
tarsus and of the pelvis. The latter forms, the salamanders,
show a more generalized form of carpus and tarsus and of pelvis
also. In the latest forms, the Anura, the carpus and tarsus are
reduced through loss of parts, except that the astragalus and cal-
caneum are phenomenally elongate. We have then, in the Batra-
chian series, a somewhat mixed kind of change ; but it princijDally
consists of concentration and consolidation of parts. The ques-
tion as to whether this process is one of progression or retrogres-
sion may be answered as follows : If degeneracy consists in **the
loss of parts without complementary addition of other parts," then
the Batrachian line is a degenerate line. This is only partly true
of the vertebral column, which presents the most primitive char-
acters in the early, Permian, genera (Rhachitomi). If departure
from the nearest approximation to the Mammalia is degeneracy,
then the changes in this class come under that head. The carpus,
tarsus, and scapular and pelvic arches of the Rachitomi are more
Mammalian than are those of any of their successors. ||

* The Trachystomata probably came from the Urodela by a process of degener-
acy. See "American Naturalist," Dec, 1 885. (Ed. 1886.)

f Includes the Eryopidae.

X Includes Trimcrorhachidae and Archegosauridae ; and is distinguished from the
Rhachitomi only by the presence of a single and cotyloid articulation of the skull
with the atlas.

* This reduction extends to the dorsal series as well. (Ed. 1S8G.)

11 This should read, than their latest, or anurous successors. (Ed. 1886.)

EVOLUTIOI!^ OF THE VERTEBRATA. 333

There are several groups which show special marks of degen-
eracy. Such are the reduced maxillary bones and persistent gills
of the Proteida; the absence of the maxillary bones and the
presence of gills in the Trachystomata ; the loss of a pair of legs
and feebleness of the remaining pair in the sirens ; and the ex-
treme reduction of the limbs in Amphiuma. Such I must also
regard, with Lankester, the persistent branchiae of the Siredons.
I may add that in the brain of the Proteid Necturus the hemi-
spheres are relatively larger than in the Anura, which are at the
end of the line.

It must be concluded, then, that in many respects the Ba-
trachia have undergone degeneracy with the passage of time.

VI. THE KEPTILIAl:^ LIKE.

As in the case of the Batrachia, the easiest way of obtaining a
general view of the history of this class is by throwing their prin-
cipal structural characters into a tabular form. As in the case of
that class, I commence with the oldest forms and end with the
latest in the order of time, which, as usual, corresponds with
the order of structure. I except from this the first order, the
Ichthyopterygia, which we do not know prior to the Triassic
period : *

A. Extremities not differentiated in form beyond proximal segment.

I. Os quadratum immovably articulated to squamosal, etc.

Tubercular and capitular rib-articulations present and distinct. . .1. Ichthyopterygia.
AA. Elements of extremities differentiated.

II. Os quadratum immovably articulated ; capitular and tubercular rib-articula-

tions distinct. Archosauria.
Pubis and ischium united, and with little or no obturator foramen ; one posterior

cranial arch ; limbs ambulatory ; a procoracoid 2. Theromorpha.

Ischium and pubis distinct, the latter directed forward, backward, or downward ;
two postei'ior cranial arches; limbs ambulatory; no procoracoid

3. Dinosawia.j-
Ischium and pubis united ; two postcranial arches ; anterior limbs volant

4. Ornlthosauria.

III. Os quadratum closely united to cranial arches ; but one rib-articulation.
Synaptosauria.

* Generally similar to the system published by me in " Proceedings Amer. Ass.
Adv. Science," xix, p. 233.

f This definition includes the Crocodilia in the Dinosauria, as it is absolutely
connected with the typical Dinosaurs by the Opisthocoela (Sauropoda Marsh).

334 THE STPwUCTURAL EVIDENCE OF EVOLUTION.

Distinct hyposternal and postabdominal bones ; ribs joining each two vertebrae, and
generally forming a carapace ; one posterior cranial arch 5. Testudinata.

Hyposternal and postabdominal bones not distinct ; two posterior cranial arches ;
ribs attached to one vertebra ; a sternum ; ? no procoracoid

6. RhyncliocepJialia.

Hyposternal and postabdominal bones not distinct ; two posterior cranial arches ;
ribs attached to one centrum ; no sternum ; * a procoracoid . . Y. Sauropterygia.

IV. Os quadratum attached only at the proximal extremity, and more or less
movable; ribs with one head. Streptostylica.f
Brain-case membranous in front of prootic bone ; trabecula not persistent

8. Lacertilia.
Brain-case with osseous walls anterior to prootic ; a scapular arch and sternum

9. PythonomorpJia.

Brain-case with osseous walls anterior to prootic ; no scapular arch nor sternum ;

trabecular grooves of sphenoid and presphenoid bones 10. Ophidia.

An inspection of the characters of these ten orders, and their
consideration in connection with their geological history, will give
a definite idea as to the character of their evolution. The history
of the class, and therefore the discussion of the question, is limited
in time to the period which has elapsed since the Permian epoch
inclusive, for it is then that the Eeptilia enter the field of our
knowledge. During this period but one order of reptiles in-
habited the earth, so far as now known, that of the Theromorpha.
The important character and role of this type may be inferred
from the fact that they are structurally nearer to both the Ba-
trachia and the Mammalia than any other, but present characters
which render it probable that all the other reptiles, with possibly
the exception of the Ichthyopterygia, derived their being from
them. The phylogeny may be thus expressed :

Dinosauria Testudinata Ehynchocephalia Lacertilia Ophidia

~ \ /

Pythonomorpha J

(Crocodilia)
Pterosauria

DinosauriaX Sauropterygia^

/
/
/

Ichthyopterygia Theromorpha

* Episternum present.

f It is quite possible that the three divisions of this head form one natural
order, the Streptostylica, or Squamata.

X Some unknown type of this order will represent the ancestor of the Ophidia,
while the Lacertilia may have come directly from the Theromorpha. (Ed. 1886.)

EVOLUTION OF THE VERTEBRATA. 335

In the first jDlace, this line departs with lapse of time from the
primitive and ancestral order, the Theromorpha, in two respects :
First, in the loss of the capitular articulation of the ribs, and, sec-
ond, in the gradual elongation and final freedom of the suspensory
bone of the lower jaw (the os quadratum). In so departing from
the Theromorpha, it also departs from the mammalian type. The
ribs assume the less perfect kind of attachment which the mam-
mals only exhibit in some of the whales, and the articulation of
the lower jaw loses in strength, while it gains in extensibility, as
is seen in the development of the line of the eels among fishes.
The end of this series, the snakes, must therefore be said to be
the result of a process of creation by degeneration, and their lack
of scapular arch and fore limb and usual lack of pelvic arch and
hind limb, are confirmatory evidence of the truth of this view of
the case.

Secondly, as regards the ossification of the anterior part of the
brain-case. This is deficient in some of the Theromorpha, the an-
cestral order, which resemble in this, as in many other things,
the contemporary Batrachia. Some of them, however (Diadecti-
dae), have the brain comjDletely inclosed in front. The late orders
mostly have the anterior walls membranous, but, in the strepto-
stylicate series at the end, the skull in the snakes becomes en-
tirely closed in front. In this respect, then^ the latter may be
said to be the highest or most perfect order.

As regards the scapular arch, including the sternum, no order
l^ossesses as many elements as thoroughly articulated for the use
of the anterior leg as the Permian Theromorpha, though the cor-
acoid is of reduced size. In all the orders there is loss of parts,
excepting only in the Ornithosauria and the Lacertilia. In the
former the adaptation is to flying. The latter retain nearly the
Theromorph type, enlarging the coracoid. An especial side de-
velopment is the modification of abdominal bones into two pecul-
iar elements to be united with the scapular arch into a plastron,
seen in the Testudinata. In this part of the skeleton the orders
are generally degenerate, the last one, the Ophidia, especially so.

The pelvic arch has a more simple history. Again, in the
Theromorpha we have the nearest approach to the Mammalia.
The only other order which displays similar characters is the
Ornithosauria (Dimorphodon, according to Seeley). In the Dino-
sauria we have a side modification which is an adaptation to the
erect or bipedal mode of progression, the inferior bones being

336 THE STRUCTURAL EVIDENCE OF EVOLUTION.

thrown backward so as to support the viscera in a more posterior
position. This is an obvious necessity to a bipedal animal where
the vertebral column is not perpendicular, as in birds. And it
is from the Dinosauria that the birds are supposed to have arisen.
(Plates XV and XVI.) The main line of the Eeptilia, however,
departs from both the mammalian and the avian type and loses
in strength as compared with the former. In the latest orders,
the Phythonomorpha and Ophidia, the pelvis is rudimental or
absent.

As regards the limbs, the degeneracy is well marked. No
reptilian order of later ages apj^roaches so near to the Mammalia
in these parts as do the Permian Theromorpha. This approxi-
mation is seen in the internal epicondylar foramen and well-devel-
oped condyles of the humerus, and in the well-differentiated
seven bones of the tarsus. The epicondylar foramen is only re-
tained in later reptiles in the Ehynchocephalian Hatteria (Dollo) ;
and the condyles of the Dinosauria and all of the other orders,
excepting the Ornithosauria and some Lacertilia, are greatly
wanting in the strong characterization seen in the Theromorpha.
The posterior foot seems to have stamped out the greater part of
the tarsus in the huge Dinosauria, and it is reduced, though to a
less degree, in all the other orders. In the paddled Sauroptery-
gia, dwellers in the sea, the tarsus and carpus have lost all char-
acterization, probably by a process of degeneracy, as in the mam-
malian whales. This is to be inferred from the comparatively
late period of their appearance in time. The still more unspecial-
ized feet and limbs of the Ichthyosaurus (Ichthyopterygia) can
not yet be ascribed to degeneracy, for their history is too little
known. At the end of the line, the snakes present us with another
evidence of degeneracy. But few have a pelvic arch (Stenostomi-
dse Peters), while very few (Peropoda) have any trace of a poste-
rior limb.

The vertebrae are not introduced into the definitions of the
orders, since they are not so exclusively distinctive as many other
parts of the skeleton. They nevertheless must not be overlooked.
As in the Batrachia, the Permian orders show inferioritv in the
deficient ossification of the centrum. Many of the Theromorpha
are notochordal, a character not found in any later order of
reptiles excepting in a few Lacertilia (Gecconidaa). They thus
differ from the Mammalia, whose characters are approached more
nearly by some of the terrestrial Dinosauria in this respect.

EVOLUTION OF THE VERTEBRATA. 337

Leaving this order, we soon reach the prevalent ball-and-socket
type of the majority of Reptilia. This strong kind of articula-
tion is a need which accompanies the more elongated column
which itself results at first from the posterior direction of the
ilium. In the order with the longest column, the Ophidia, a sec-
ond articulation, the zygosphen, is introduced. The mechanical
value of the later reptilian vertebral structure is obvious, and in
this respect the class may be said to present a higher or more
perfect condition than the Mammalia.

In review it may be said of the reptilian line, that it exhibits
marked degeneracy in its skeletal structure since the Permian
epoch ; the exception to this statement being in the nature of the
articulations of the vertebrae. And this specialization is an adap-
tation to one of the conditions of degeneracy, viz., the weakening
and final loss of the limbs and the arches to which they are at-
tached.

The history of the development of the brain in the Eeptilia
presents some interesting facts. In the Diadectid family of the
Permian Theromorpha it is smaller than in a Boa constrictor,
but larger than in some of the Jurassic Dinosauria. Marsh has
shown that some of the latter possess brains of relatively very
narrow hemispheres, so that in this organ those gigantic reptiles
were degenerate, while the existing streptostylicate orders have
advanced beyond their Permian ancestors.

There are many remarkable cases of what may now be safely
called degradation to be seen in the contents of the orders of
reptiles.* Among tortoises may be cited the loss of the rib-
heads and of one or two series of phalanges in the especially
terrestrial family of the Testudinidae. The cases among the
Lacertilia are the most remarkable. The entire families of the
Pygopodidse, the Aniellidse, the Anelytropidae, and the Dibamidae
are degraded from superior forms. In the Anguidae, Teidae, and
Scincidae, we have series of forms whose steps are measured by
the loss of a pair of limbs, or of from one to all the digits, and
even to all the limbs. In some series the surangular bone is lost.
In others the eye diminishes in size, loses its lids, loses the folds
of the epidermis which distinguishes the cornea, and finally is en-
tirely obscured by the closure of the ophthalmic orifice in the

* Such forms in the Lacertilia have been regarded as degradational by Lan-
!ou]

kester and Bouhmger,

PLATE XV.

cS
o

o
o

• r-H

CS
02

r— t

P
CO
o

PLATE XVI.

Diclonius mirabilis skull, one seventh natural size, from below.

340 THE STRUCTURAL EVIDEISrCE OF EVOLUTION.

true skin. Among the snakes a similar degradation of the organs
of sight has taken place in the order of the Scolecophidia, which
live underground, and often in ants' nests. The Tortricidae and
UropeltidsB are burro wing-snakes which display some of the earlier
stages of this process. One genus of the true snakes even (accord-
ing to Giinther) has the eyes obscured as completely as those of
the inferior types above named (genus Typhlogeophis).

YII. THE AVIAIiT LINE.

The paleontology of the birds not being well known, our con-
clusions respecting the character of their evolution must be very
incomplete. A few lines of succession are, however, quite ob-
vious, and some of them are clearly lines of progress, and others
are lines of retrogression. The first bird we know at all com-
pletely, is the celebrated Archeoj^teryx of the Solenhofen slates
of the Jurassic period. In its elongate series of caudal vertebrae
and the persistent digits of the anterior limbs we have a clear in-
dication of the process of change which has produced the true
birds, and we can see that it involves a specialization of a very
pronounced sort. The later forms described by Seeley and Marsh
from the Cretaceous beds of England and North America, some
of which have biconcave vertebrae, and all probably, the American
forms certainly, possessed teeth. This latter character was evi-
dently speedily lost, and others more characteristic of the subclass
became the field of developmental change. The parts which sub-
sequently attained especial development are the wings and their
appendages ; the feet and their envelopes, and the vocal organs.
Taking all things into consideration, the greatest sum of progress
has been made by the perching birds, whose feet have become
effective organs for grasping, whose vocal organs are most perfect,
and whose flight is generally good, and often very good. In
these birds also the circulatory system is most modified, in the
Ibss of one of the carotid arteries.

The power of flight, the especially avian character, has been
developed most irregularly, as it appears in all the orders in
especial cases. This is apparent so early as in the Cretaceous
toothed birds already mentioned. According to Marsh the Hes-
peornithidae have rudimental wings, while these organs are well
developed in the Ichthyornithidae. They are well developed
among natatorial forms in the albatrosses and frigate pelicans,
and in the skuas, gulls, and terns ; among rasorial types the

EVOLUTION OF THE VERTEBRATA. 341

sand-grouse, and, among the adjacent forms, the pigeons. Then
among the lower insessores, the humming-birds exceed all birds
in their powers of flight, and the swifts and some of the Capri-
mulgidae are highly developed in this respect. Among the higher
or true song birds, the swallows form a notable example. With
these high specializations occur some remarkable deficiencies.
Such are the reduction of the feet in the Caprimulgidae, swifts,
and swallows, and the foetal character of the bill in the same
families. In the syndactyle families, represented by the king-
fishers, the condition of the feet is evidently the result of a pro-
cess of degeneration.

A great many significant points may be observed in the
developmental history of the epidermic structures, especially in
the feathers. The scale of change in this respect is in general a
rising one, though various kinds of exceptions and variations
occur. In the development of the rectrices (tail-feathers) there
are genera of the wading and rasorial types, and even in the in-
sessorial series, where those feathers are greatly reduced or abso-
lutely wanting. These are cases of degeneracy.

There is no doubt that the avian series is in general an as-
cending one.

VIII. THE MAMMALIAN" LIXE.

Discoveries in paleontology have so far invalidated the ac-
cepted definitions of the orders of this class that it is difficult to
give a clearly cut analysis, especially from the skeleton alone.
The following scheme, therefore, while it expresses the natural
groupings and affinities, is defective in that some of the defini-
tions are not without exceptions :

I. A large coracoid bone articulating with the sternum.
Marsupial bones ; fibula articulating with proximal end of astragalus

1. Monotrcmata.

II, Coracoid a small process co-ossified with the scapula.

o. Marsupial bones ; palate with perforations (vagina double ; placenta and
corpus callosum rudimental or wanting; cerebral hemispheres small
and generally smooth).

But one deciduous molar tooth 2. Marsupialia.

aa. No marsupial bones; palate entire (one vagina; placenta and corpus
callosum well developed).
j8. Anterior limb reduced to more or less inflexible paddles, posterior
limbs wanting (Mutilata).

342 THE STRUCTURAL EVIDENCE OF EVOLUTION.

No elbow-joint ; carpals discoid, and with the digits separated by cartilage ; lower

jaw without ascending ramus 3. Cetacea,

An elbow-joint ; carpals and phalanges m ith normal articulations ; lower jaw with

ascending ramus 4. Sirenia.

j8^. Anterior limbs with flexible joints and distinct digits ; ungual pha-
langes not compressed and acute at apex* (Ungulata f).
y. Tarsal bones in linear series ; carpals generally in linear series.

Limbs ambulatory ; teeth with enamel 5. Taxeojxxla.X

77. Tarsal series alternating; carpal series linear.
Cuboid bone partly supporting navicular, not in contact with astragalus . 6. Prohoscidia.

777. Both tarsal and carpal series more or less alternating.
Os magnum not supporting scaphoides ; cuboid supporting astragalus ; superior

molars tritubercular 7. Arahlijpoda.

Os magnum supporting scaphoides ; superior molars quadritubercular *

8. Diplarthra,\
/3/3j3. Anterior limbs with flexible joints. Ungual phalanges compressed
and pointed-^ (Unguiculata).
e. Teeth without enamel; no incisors.

Limbs not volant; hemispheres small, smooth 9. Edentata.

66. Teeth with enamel ; incisors present.
No postglenoid process ; mandibular condyle round ; limbs not volant ; hemispheres

small, smooth 10. Rodentia.

Limbs volant ; hemispheres small, smooth 11. Chiroptera.

* Except the Ilapalidse. f Lamarck, "Zoologie Philosophique," 1809.

X This order has the following suborders, whose association is now made for the
first time :

Carpal series linear ; no intermedium ; fibula not interlocking with astragalus ; no

anapophyses ; incisors rooted ; hallux not opposable. Condylartha.

Carpal series linear ; an intermedium ; fibula interlocking with astragalus ; hallux

not opposable Hyracoidea.

An intermedium ; fibula not interlocking ; anapophyses ; hallux opposable ; incisors

growing from persistent pulps Dauhentonoidea.

An intermedium ; fibula not interlocking ; anapophyses; hallux opposable ; incisors

rooted ; carpus generally linear Qiiadt^mana.

No intermedium ; * nor anapophyses ; carpal rows alternating ; incisors rooted

A nthropoidea.\
The only difference between the Taxeopoda and the Bunotheria is in the unguli-
form terminal phalanges of the former as compared with the clawed or unguiculate
form in the latter. The marmosets among the former division are, however, fur-
nished with typical claws.

Some may prefer to use the term Primates in place of Taxeopoda, and such may
be the better course.

* Except Pantolestes.

II This order includes the suborders Pcrissodactyla and Artiodactyla. It is the
Ungulata of some authors.
^ Except Mesonyx.

* Except in Sijnia and Hylobates. t Includes the Anthropoid apes and man.

EYOLUTTON OF THE YERTEBRATA.

843

A postglenoid process; mandibular condyle transverse; limbs not volant; no
scapholunar bone;* hemispheres small, smooth 12. BuiiotheriaA

A postglenoid process ; limbs not volant, with a scapholunar bone ; hemispheres
larger, convoluted 13. Carnivora.

Paleontology has cleared up the phylogeny of most of these
orders, but some of them remain as yet unexplained. This is the
case with the Cetacea, the Sirenia, and the Taxeopoda. The
last-named order and the Marsupialia can be supposed with much
probability to have come oS from the Monotremata, but there is
as yet no paleontological evidence to sustain the hypothesis. Xo
progress has been made in unraveling the phylogeny of the Ceta-
cea and Sirenia. The facts and hypotheses as to the phylogeny
of the Mammalia may be representad in the following diagram :

Diplarthra Hyracoidea Insectivora Rodentia Chiroptera

Proboscidea
Amblypoda

Anthropoidea

I
Qaadrumana

Edentata

Carnivora

Sirenia
Cetacea

Tillodonta
Ta3niodonta [ Oreodonta

Oondylartbra
Marsupialia pt.J.
Monotremata

Marsupialia pt.

It will be readily seen from the above diagram that the dis-
covery of the Condylarthra was an important event in the history
of our knowledge of this subject. This suborder of the Lower
Eocene epoch stands to the placental Mammalia in the same rela-
tion as the Theromorphous order does to the reptilian orders. It
generalizes the characteristics of them all, and is apparently the
parent stock of all, excepting, perhaps, the Cetacea. The dis-
covery of the extinct Bunotherian suborders united together in-
separably the clawed orders, excepting the bats ; while the extinct
order Amblypoda is the ancestor of the most specialized of the
Ungulates, the odd- and even-toed Diplarthra.

The characters of the skeleton of the order Monotremata show
that it is nearest of kin to the Reptilia, and many subordinate

* Except Erinaceus.

f With the suborders Insectivora, Oreodonta, Taeniodonta, and Tillodonta.

X This was inadvertently omitted in the original. (Ed. 1886.)

34:4: THE STRUCTURAL EVIDENCE OF EYOLUTIOX.

characters point to tlie Theromorplia as its ancestral source.* In
the general characters the Marsupialia naturally follow in a rising
scale, as proved by the increasing perfection of the reproductive
system. The Monodelphia follow with improvements in the re-
productive system and the brain, as indicated in the table already
given. The oldest Monodelphia were, in respect to the structure
of the brain, much like the Marsupialia, and some of the existing
orders resemble them in some parts of their brain-structure.
Such are the Condylarthra and Amblypoda of extinct groups,
and the Bunotheria, Edentata, Rodentia, and Chiroptera, recent
and extinct. The characters of the brains of Amblypoda and some
Oreodonta are, in their superficial characters, even inferior to ex-
isting marsupials. The divided uterus of the recent forms named,
also gives them the position next to the Marsupialia. In the Car-
nivora, Hyracoidea, and Proboscidia, a decided advance in both
brain-structure and reproductive system is evident. The hemi-
spheres increase in size, and they become convoluted. A uterus
is formed, and the testes become external, etc. In the Quadru-
mana the culmination in these parts of the structure is reached,
excepting only that, in the lack of separation of the genital and
urinary efferent ducts, the males are inferior to those of many of
the Artiodactyla. This history displays a rising scale for the
Mammalia.

Looking at the skeleton, we observe the following successional
modifications : f

First, as to the feet, and (A) the digits. The Condylarthra
have five digits on both feet, and they are plantigrade. This char-
acter is retained in their descendants of the lines of Anthropoidea,
Quadrumana, and Hyracoidea, also in the Bunotheria, Edentata,
and most of the Rodentia. In the Amblypoda and Proboscidia
the palm and heel are a little raised. In the Carnivora and Dip-
larthra the heel is raised, often very high, above the ground, and
the number of toes is diminished, as is well known, to two in the
Artiodactyla and one in the Perissodactyla. (B) The tarsus and
carpus. In the Condylarthra the bones of the two series in the
carpus and tarsus are opposite each other, so as to form continuous
and separate longitudinal series of bones. This continues to be

* "Proceedings American Philosoph. Society," 18S4, p. 43.
f See the evidence for evolution in the history of the extinct Mammalia. " Pro-
ceeds. Araer. Assoc. Adv. Science," 1883.

PLATE XVII.

346 THE STRUCTURAL EVIDENCE OF EVOLUTION".

the case in the Hyracoidea and many of the Quadrumana, but in
the anthropoid apes and man the second row is displaced inwards
so as to alternate with the first row, thus interrupting the series in
the longitudinal direction, and forming a stronger structure than
that of the Condylarthra. In the Bunotherian Rodent and Eden-
tate series, the tarsus continues to be without alternation, as in
the Condylarthra, and is generally identical in the Carnivora. In
the hoofed series proper it undergoes change. In the Proboscidia
the carpus continues linear, while the tarsus alternates. In the
Amblypoda the tarsus alternates in another fashion, and the car-
pal bones are on the inner side linear, and on the outer side alter-
nating. The complete interlocking by universal alternation of the
two carpal series is only found in the Diplarthra. (C) As to the
ankle-joint. In most of the Condylarthra it is a flat joint or not
tongued or grooved. In most of the Carnivora, in a few Rodentia,
and in all Diplarthra, it is deeply tongued and grooved, forming a
more perfect and stronger joint than in the other orders, where
the surfaces of the tibia and astragalus are flat. (D) In the high-
est forms of the Rodentia and Diplarthra the fibula and ulna be-
come more or less co-ossified with the tibia and radius, and their
middle portions become attenuated or disappear.

Secondly, as regards the vertebras. The mutual articulations
(zygapophyses) in the Condylarthra have flat and nearly horizon-
tal surfaces. In higher forms, especially of the ungulate series,
they become curved, the posterior turning upward and outward,
and the anterior embracing them on the external side. In the
higher Diplartha this curvature is followed by another curvature
of the postzygapophysis ujDward and outward, so that the vertical
section of the face of this process is an S. Thus is formed a very
close and secure joint, such as is nowhere seen in any other
Vertebrata.

Thirdly, as regards the dentition. Of the two tjipes of Mono-
tremata, the Tachyglossidse and the Platypodid£e, the known gen-
era of the former possess no teeth, and the known genus of the
latter possesses only a single corneous epidermic grinder in each
jaw. As the Theromorphous reptiles from which these are de-
scended have well-developed teeth, their condition is evidently one
of degeneration, and we can look for well-toothed forms of Mono-
tremata in the beds of the Triassic and Jurassic periods. Perhaps
some such are already known from jaws and teeth. In the mar-
supial order we have a great range of dental structure, which almost

EYOLUTIOISr OF THE VERTEBRATA. 347

epitomizes that of the Monodelph orders. The dentition of the
carnivorous forms is creodont ; that of the kangaroos is perisso-
dactyle, and that of the wombats is rodent. Other forms repeat
the Insectivora. I therefore consider the phicental series espe-
cially. I have already shown that the greater number of the types
of this series have derived the characters of their molar teeth from
the stages of the following succession. First, a simple cone or
reptilian crown, alternating with that of the other jaw. Second,
a cone with lateral denticles. Third, the denticles to the inner
side of the crown forming a three-sided prism, with tritubercular
apex, which alternates with that of the opposite jaw. Fourth,
development of a heel projecting from the posterior base of the
lower jaw, which meets the crown of the superior, forming a
tubercular-sectorial inferior molar. From this stage the carnivo-
rous and sectorial dentition is derived, the tritubercular type being
retained. Fifth, the development of a posterior inner cusp in the
superior molar, and the elevation of the heel in the inferior molar,
with the loss of the anterior inner cusp. Thus the molars become
quadritubercular, and opposite. This is the type of many of the
Taxeopoda, including the Quadrumana and Insectivora as well as
the inferior Diplarthra. The higher Taxeopoda (Hyracoidea) and
Diplarthra add various complexities. Thus the tubercles become
flattened and then concave, so as to form Vs in the section pro-
duced by wearing ; or they are joined by cross- folds, forming vari-
ous patterns. In the Proboscidia the latter become multii^lied so
as to produce numerous cross-crests.

The dentition of some of the Sirenia is like that of some of
the Ungulata, especially of the suilline group, while in others the
teeth consist of cvlinders. In the Cetacea the molars of the old-
est (Eocene and Miocene) types are but two-rooted and com-
pressed, having much the form of the premolars of other Mam-
malia. In existing forms a few have simple conical teeth, while
in a considerable number teeth are entirely wanting.

A review of the characters of the existing Mammalia as com-
pared with those of their extinct ancestors displays a great deal
of improvement in many ways, and but few instances of retro-
gression. The succession in time of the Monotremata, the Mar-
supialia, and the Monodelphia, is a succession of advance in all
the characters of the soft parts and of the skeleton which define
them (see table of classification). As to the monotremes them-
selves, it is more than probable that the order has degenerated in

348 THE STRUCTURAL EVIDENCE OF EVOLUTION.

some res]3ects in producing the existing types. The history of the
Marsupialia is not made out, but the earliest forms of which we
know the skeleton, Polymastodon (Cope) of the Lower Eocene, is as
specialized as the most specialized recent forms. The dentition of
the Jurassic forms, Plagiaulax, etc., is quite specialized also, but
not more so than that of the kangaroos. The premolars are more
specialized, the true molars less specialized than in those animals.

Coming to the Monodelphia, the increase in the size and com-
plication of the brain, both of the cerebellum and the hemi-
spheres, is a remarkable evidence of advance. But one retro-
gressive line in this respect is known, viz., that of the order
Amblypoda,* where the brain has become relatively smaller with
the passage of time. The successive changes in the structure of
the feet are all in one direction, viz., in the reduction of the
number of the toes, the elevation of the heel, and the creation of
tongue and groove joints where plain surfaces had previously ex-
isted. The diminution in the number of toes might be regarded
as a degeneracy, but the loss is accompanied by a proportional
gain in the size of the toes that remain. In every respect the
progressive change in the feet is an advance. In the carpus and
tarsus we have a gradual rotation of the second row of bones on
the first, to the inner side. In the highest and latest orders this
process is most complete, and, as it results in a more perfect me-
chanical arrangement, the change is clearly an advance. The
same progressive improvement is seen in the development of dis-
tinct facets in the cubito-carpal articulation, and of a tongue and
groove (^* in tertrochlear crest ") in the elbow-joint. In the ver-
tebrae the development of the interlocking zygapophysial articula-
tions is a clear advance.

Progress is generally noticeable in the dental structures ; for,
unlike the marsupial line, the earliest dentitions are the most
simple, and the later the more complex. Some of the types re-
tain the primitive tritubercular molars, as the Centetidae, shrews
and some lemurs, and many Carnivora, but the quadritubercular
and its derivative forms are by far the most common type in the
recent fauna. The forms that produced the complicated modifica-
tions in the Proboscidia and Diplarthra appeared latest in time,
and the most complex genera. Bos and Equus, the latest of all.
The extreme sectorial modifications of the tritubercular type, as

* See "Naturalist," Jan., 1885, p. 55.

EVOLUTION OF THE YERTEBRATA. 349

seen in the Hyaenidge and the Felidae, are the latest of their line
also.

Some cases of degeneracy are, however, apparent in the mono-
delphous Mammalia. The loss of pelvis and posterior limbs in
the two mutilate orders is clearly a degenerate character, since
there can be no doubt that they have descended from forms
with those parts of the skeleton present. The reduction of flexi-
bility seen in the limbs of the Sirenia and the loss of this char-
acter in the fore limbs of the Cetacea are features of degeneracy
for the same reason. The teeth in both orders have undergone
degenerate evolution ; in the later and existing forms of the Ceta-
cea even to extinction. The Edentata appear to have undergone
degeneration. This is chiefly ajoparent in the teeth, which are
deprived of enamel, and which are wanting from the premaxillary
bone. A suborder of the Bunotheria, the Tgeniodonta of the
Lower Eocene period, display a great reduction of enamel on the
molar teeth, so that in much-worn examjoles it appears to be
wanting. Its place is taken by an extensive coat of cementum,
as is seen in Edentata, and the roots of the teeth are often un-
divided as in that order. It is probable that the Edentata are the
descendants of the Tseniodonta by a process of degeneracy.

Local or sporadic cases of degenerate loss of parts are seen in
various parts of the mammalian series, such as toothless jMamma-
lia wherever they occur. Such are cases where the teeth become
extremely simple, as in the honey-eating marsupial Tarsipes, the
carnivore Proteles, the Pteropod bats, and the aye-aye. Also where
teeth are lost from the series, as in the canine genus Dysodus, and
in man. The loss of the hallux and pollex without corresponding
gain in various genera, may be regarded in the same light.

In conclusion, the progressive may be compared with the re-
trogressive evolution of the Vertebrata, as follows : In the earlier
periods and with the lower forms, retrogressive evolution pre-
dominated. In the higher classes progressive evolution has pre-
dominated. When we consider the history of the first class of
vertebrates, the Tunicata, in this respect, and compare it with
that of the last class, the Mammalia, the contrast is very great.

PART III.

MECHAIs^IOAL EYOLUTIOE".

XII.

THE EELATION OF ANIMAL MOTION TO ANIMAL

EVOLUTION.

To explain the origin of variation in animal structure is, par
excellence, the object of the doctrine of evolution. There can be
little doubt that the law of natural selection includes the cause of
the preservation of certain modifications of pre-existent structure,
in preference to others, after they have been brought into exist-
ence. In what manner or by what process the growing tissues of
young animals have been so affected as to produce some organ or
part of an organ which the parent did or does not possess, must
be explained by a different set of laws. These have been termed
originative^ while those involved in natural selection are restrictive
only.

Of course we naturally look to something in the *^ surrounding
circumstances" in which a plant or animal is placed, or its "en-
vironment," as the most probable stimulant of change of its char-
acter, because we know that such beings are totally dependent on
cosmic and terrestrial forces for their sustenance and preservation.
The difficulty has been to connect these forces with change of
structure SLS originative ; to show their operation as multiplying,
restricting or destroying organisms already in existence is compar-
atively easy. This difficulty is partially due to the fact that such
modifications must be realized during a limited portion of the life
of an animal at least ; that is, during the period of growth, when
it is not at all or but little subject to the influence of external en-
vironment, but is usually protected or supported by the parent.

That the environment and changes in it affect the movements

RELATION OF ANIMAL MOTION TO ANIMAL EVOLUTION. 351

of plants and animals is clear enough. The potency of such
changes may be read in the physical history of the earth. A long
series of modifications preceded the advent of life upon it, and
change, both gradual and sudden, has been exhibited in the con-
figuration and climate of all portions of the surface of the globe
since that period. Animals have again and again been called
upon to face new conditions, and myriads of species have fallen
victims to the inflexibility of their organization which has pre-
vented adaptation to new surroundings. But it is evident that if
change of environment has had any influence in the progress of
evolution, it has not been alone destructive. It has preceded life
as well as death, and has furnished the stimulus to beings capable
of change, while it has destroyed those which were incapable of
it. It is a truism that change of physical conditions has preceded
all great faunal changes, and that the necessity for new mechanism
on the part of animals has always preceded the appearance of new
structure in geologic times.

The embryology and paleontology of vertebrated animals show
that the primary steps in the progress of this branch of the animal
kingdom are marked by the successive changes in the structure of
the circulatory system. First we have the various mechanical
methods for the aeration of blood in a watery medium ; the result
being a fluid whose metamorphosis in nutrition produces no heat.
After the fishes followed Batrachia, the earliest air-breathers,
whose long tarriance to-day in early aquatic stages is an epitome
of the necessarily *' amphibious" character of air-breathing verte-
brate life, when land and fresh water, in constantly changing
areas, were rising and separating from the universal ocean. The
successive disappearances of the traces of the fish type of circula-
tion in Batrachia and reptiles, are familiar facts ; and the exclu-
sion of the unaerated blood from the systemic circulation in the
birds and mammals marks the increase of general temperature
which gives those classes one of their claims to sui)eriority.

The appearance of land of course furnished the opportunity
for aquatic animals to assume a terrestrial life. Marine animals
which had acquired the habit of gulping air from the surface,
which some of them now possess, perhaps because its richness in
oxygen produced an agreeable exaltation or intoxication, would
not find visits to the land difficult. And this would naturally
follow the necessity of escape from aquatic enemies, or the search
for new supplies of food.

352 MECHANICAL EVOLUTION.

In fine, it requires little argument to sliow that the enyiron-
ment has had in the past, as in the present, a primary influence
over the movements of animals.

II.

I will now endeavor to exhibit some reasons for believing that
the movements of animals affect their structure directly.

There are two alternative propositions expressive of the rela-
tions of the structures of animals to their uses. Either the use
or attempt to use preceded the adaptive structure, or else the
structure preceded and gave origin to the use. The third alter-
native, that use and structure came into being independently of
each other, is too improbable for consideration in the present
article. Many facts render the first of these propositions much
the more probable of the two.

A general ground for suspecting that movement affects struct-
ure is the fact well known to systematic zoologists, that adaptive
characters are the least reliable in systematic classification, i. e.,
are the most variable. What we call adaptive characters are
those whose teleological significance we can most easily perceive ;
those whose uses are at the present time most obvious. System-
atists habitually fall back on characters which are apparently the
least related to the ordinary necessities of the life of the animal,
and this not from any theoretical considerations, but because such
characters are found to be the most constant. This is a very sig-
nificant fact, showing as it does that it is the adaptive structures
which are undergoing modification to-day. And this truth can
doubtless be discerned in all past ages, for many of the structures
which are not now more related to the needs of an animal than
many others might be, were at one time most essential to its well-
being, or necessarily related to its environment. Such are the
structural characters of the heart and arteries already enumerated.
There seems to be no reason why all Vertehrata might not exist
with equal comfort and success at the present if possessed of a
uniform organization in this respect. But the successive modi-
fications which they present were, in past ages, most intimately
connected with the progressive changes of the medium in which
they lived, as to the volume of oxygen su23plied for respiration,
as compared with that of the vapor of water, carbonic acid gas,
etc. But it must be here noted, in passing, that there are many
structures in animals which have never been adaptive, but which

RELATION OF ANIMAL MOTION TO ANIMAL EVOLUTION. 353

are simjoly due to excess or defect of nutrition following a redis-
tribution of force.*

The most direct evidence in support of the view that motion
affects structure directly is to be found in the well-known phe-
nomenon of the increase of the size and power of all organs by
use. This increase is limited in the adult animal by the general
fixity of all the organs, so that one of them cannot be developed
beyond a certain point without injury to others, or without ex-
hausting the source of supply of nutritive material or special force '
derived from other organs. The syncope of the gymnast is an
illustration of the natural limitation to the development of the 1
muscular system which proceeds at the expense of the digestive
and circulatory. But effort and exertion may become a habit of
mind, which, even if limited in its executive means, is probably in-
herited by offspring like all other mental traits. Such a quality
possessed by an infant or child doubtless tells on the growth of \
its organs during their plastic stage, and produces structure by \
growth which is impossible to the mature body.f And no one
knows as yet how far mental bias may affect the nutrition of the
parts of the infant in utero. Certain it is, that if use modifies
nutrition in the adult, it must have still greater influence in the
young ; and it is in the young that tlie changes which constitute
evolution necessarily appear.

Change of structure during growth is accomplished either by
addition of parts (^^acceleration") or by subtraction of parts
("retardation").

Acceleration is produced either by multiplication of parts (as
cells or segments) already present (^Miomotopy "), or by the
transfer of parts (cells) from one part of the organism to the
other (*^heterotopy "). Homotopy or repetition is the usual and
normal mode of acceleration ; it may proceed by an " exact repeti-
tion " of the parts already existing, as in the simplest animals and
plants ; or the new parts may differ from the old, as in higher
animals, where the process is called "modified repetition." Where
new forms traverse in their growth all the stages in which they
previously existed, they necessarily present at each stage the char-
acters of those forms which have remained stationary in them, and
have not changed. This relation of " exact parallelism " is the

* "Method of Creation," 1871, p. 23.
f In raan these changes are chiefly produced in the brain.
23

354 MECHANICAL EVOLUTION.

result of the simplest form of evolution or ^^palingenesis." When
the history of growth of an advanced form does not show an
identity between its stages and the various undeveloped or lower
adult types, the relation is termed 'Mnexact parallelism," and the
type of development '' coenogenesis. ''

Change of structure is seen to take place in accordance with
the mechanical effect of three forms of motion, viz.: hj friction,
pressure and strain. Under the first two, epidermal tissues be-
come both dense and thick, as is seen on the palms and soles of
the hands and feet, and in corns. There is no doubt that strength
of the teeth is intimately connected with the hardness of the
food. Density of osseous tissue and the coossification of parts of
the skeleton, are directly associated with the force and duration
of muscular contraction. Pathology abounds in illustrations of
the determination of nutrition to new localities to meet the exi-
gencies and demands arising from new stimuli. It is only neces-
sary for a structure-producing supply of nutritive material to be
habitually determined to a new locality by oft-recurring stimulus,
for the movement to become automatic and reflex ; and such a
tendency would sooner or later be inherited, and produce struct-
ure in the growing organism of the young to a degree far exceed-
ing anything that is possible in the adult.

In view of the above considerations, we can ascribe an exten-
sive class of osseous projections at points of muscular insertion,
to the strength and duration of muscular contractions. To the
same cause may be ascribed various anchyloses, such, for instance,
as is seen in the foot of the sloth. Transverse strains or their ab-
sence may be looked upon respectively as the cause of the hinge-
like or immovable articulations of the segments of the limbs of
vertebrate animals. It is well knoAvn that in land animals, where
easy flexibility of the limbs is essential to speed, these articula-
tions are highly developed, while in marine animals, where the
limbs are only used as paddles, they are almost or quite in-
flexible, and the extremities of the bones are truncate. In the
most highly organized land Mammalia, the tibio-tarsal and hu-
mero-cubital articulations display an interlocking or tongue-
and-groove character. The same thing is seen in the ulno-
radial fixed articulation in the same types. These arrangements
are especially adapted to prevent dislocation by side strains,
and if the preceding explanations be true, this structure is
a corrugation due to the lateral pressure of a more or less

RELATION OF ANIMAL MOTION TO ANIMAL EVOLUTION. 355

convex surface, on a concave one which embraces it, and vice
versa.

In the circulatory system, pressure has doubtless played an im-
portant part. Increased oxygenation of blood, the necessary con-
sequence of the purification of the atmosphere, would stimulate
the action of all the organs, including that of the heart. Greater
pressure on its walls and septa w^ould increase their size and
strength, and ultimately close such foramina as were not in the
course of the blood current, as the foramen septi ventriculorum
of reptiles, and the/, ovale. Increased force of the current would,
on the other hand, soon cause the enlargement of one or other of
the four or five pairs of primary aorta bows, and develop it at the
expense of the others, until finally the pre-eminence of one chan-
nel be secured and the aorta be the result. This part of the sub-
ject might be prolonged to an unlimited extent, but the above
illustrations must suffice to indicate the meaning of my proposi-
tions.

III.

That movements change the environment of a plant or an ani-
mal, or parts of them, is obvious enough. If we consider only
the reflex class, to which all the movements of plants and many
of those of animals belong, we perceive that but for them the or-
dinary functions of assimilation, circulation, etc., could not be
performed ; there would be no change in the contents of their
tubes and cells, and the environment of these would be unaltered.
But when we view the movements of the higher animals, w^e j)er-
ceive the immense importance of the powers and organs of move-
ment as a factor in evolution. It may be safely assumed that,
without powers of designed or adaptive movement, life would
never have advanced beyond the stage presented by the vegetable
kingdom.

The stimuli which are effective in animal consciousness are
four, viz.: excessive temperature, hunger, danger from enemies,
and the reproductive instinct. These prompt to the movements
which we observe in animals in a wild state, and without which
it is evident that the animals themselves would soon cease to
exist.

It can not be denied that organisms which are incapable of
moving from place to place in search of food, or of migration to
escape vicissitudes of temperature, are much more completely sub-

356 ' MECHANICAL EVOLUTION.

ject to the influences of their environment than those that are ca-
l)able cf such movement. Hence animals are much more inde-
pendent of the supply of food and of temperature than are plants.
Hence also, other things being equal, the greater the powers of
motion, the greater the independence.

Powers of movement then enable animals to avoid extremes
of climate by migrations or by protective arts. They enable them
to procure food by making journeys in search of it, and by all
methods of capturing it. They furnish the agent of active defense
against enemies, and of successfully reproducing their kind.

When, through changes of level of the earth's surface, drought
has overtaken a region, animals capable of the necessary migrations
have escaped. When an irruption of destructive animal enemies
has threatened an animal population with death, those members
of it whose strength or speed insured them safety, were the sur-
vivors. When land has been encroached upon by water to such a
degree as to bring starvation on its animal inhabitants, those which
could fly or swim have sought new localities.

Since all food-supply, as well as the ability to obtain food, is
dependent on temperature, those portions of the organism which
furnish means of resistance to climatic vicissitudes have the
deepest significance in the life-history of any division of ani-
mals.

The organs of circulation and motion are generally recognized
as primary in the classification of Vertehrata. All situations where
animal life is permitted by climate, support vegetable life also ; so
each of the primary divisions of animals presents types adapted to
the use of all kinds of food ; herbivorous, omnivorous, and carniv-
orous. Accordingly, it has been found that dental and other
structures connected with digestion define divisions of secondary
value and minor extent. Paleontology shows that the origin of
such divisions is of later date than that of the great classes first
mentioned ; and each of the latter has in its day been modified in
the subordinate directions indicated bv the teeth and beak. But
here also organs of movement are of great importance ; so that the
herbivorous and carnivorous types at least, have ever in land ani-
mals (reptiles, birds and mammals) been characterized by the
structure of their feet also.

RELATION OF ANIMAL MOTION TO ANIMAL EVOLUTION, 357

IV.

It has been maintained above, that environmeut governs the
movements of animals, and that the movements of animals then
alter their environment. It has also been maintained that the
movements of animals have modified their structure so as to render
them more or less independent of their environment. The history
of animal life is in fact that of a succession of conquests over the
restraints imposed by physical surroundings. Man has attained
to a wonderful degree of emancipation from the iron bonds that
confine the lower organisms.

It becomes then all important to examine into the elements in-
volved in animal movements.

These are of the two classes, reflex and conscious. To the
former belongs the accelerated activity of muscular action and
circulation, inferred to have accompanied increase in the percent-
age of oxygen in the atmosphere, during the periods of geological
time. To the consciously performed acts belong all those due to
states of pain or pleasure in animals ; such as are excited by the
four classes of stimuli already mentioned.

Doubtless physical changes in the surrounding medium have
always produced new reflex movements in animals, and have been
a first element in evolution. Such has been the immediate cause
of change of structure m plants, and in animals so far as they are
unconscious. But consciousness brings with it limitless possibili-
ties, since it places an animal in contact with innumerable stimuli
which leave unconscious beings unaffected. All the causes which
2)rovoke the movements of higher animals are appeals to conscious-
ness, and the consequences due to movements of such beings have
only been possible through consciousness.

It is evident then that sensibility to impressions has been the
prime essential to the acquisition of new movements, and hence
of new structure, other things being equal. Another essential, not
less important, has been memory ; because without this faculty,
experience, and hence education and the acquisition of habits of
movement, are not possible.

The ascending development of the bodily structure in higher
animals has thus been, m all probability, a concomitant of the evo-
lution of mind, and the progress of the one has been dependent
in an alternating way on the progress of the other. The develop-
ment of mind has secured to animals the greatest degree of inde-

358 MECHANICAL EVOLUTION.

pendence of their enyironment of whicli tbey are capable. The
first important acquisition leading to this end was aerial respira-
tion ; the second, rapid nutrition by hot blood. And as essential
to tlie production and preservation of these, improvements in
organs of movement have been superadded to every successive
type of life.

Consciousness remains as the unresolvable factor in the process ;
as at once the measure of, and respondent to a large class of phe-
nomena.

XIIL

ON THE TRITUBERCULATE TYPE OF MOLAR TOOTH

m THE MAMMALIA.

It is now apparent that the type of superior molar tooth which
predominated during the Puerco epoch was triangular or trituber-
cular ; that is, with two external and one internal tubercles.*
Thus, of sixty-seven species of placental Mammalia of which the
superior molars are known, all but four have three tubercles of the
crown, and of the remaining sixty-five, all are triangular, except-
ing those of three species of Periptychus, and three allied forms,
which have a small supplementary lobe on each side of the median
principal inner tubercle, f

This fact is important as indicating the mode of development
of the various types of superior molar teeth, on which we have not
heretofore had clear light. In the first place, this type of molar
exists to-day only in the insectivorous and carnivorous Marsupialia ;
in the Creodonta, and the tubercular molars of such Carnivora as
possess them (excepting the plantigrades). In the L^ngulates its
persistence is to be found in the molars of the Coryphodontidae of
the Wasatch, and Dinocerata of the Bridger Eocenes. In later
epochs it is occasionally seen only in the last superior molar.

The tritubercular or triangular superior molar is associated
with a corresponding form of the anterior part of the inferior
molar. This kind of inferior molar X I have called the tubercular

* See " American Naturalist," April, 1883, p. 407.

f This type is tlierefore only an extension of the tritubercular. (Ed. 18S6.)
X See Report G. M. Wheeler, D. Chief of Engineers on Explor. Surv. W. 100th
Mer., vol. iv, pt. ii ; on the Creodonta,

360

MECHAII^ICAL EVOLUTION.

sectorial, and is very variable as to the degree of development of
the sectorial cutting edge. The anterior triangle is formed by
the connection, by angle or crest, of the median and anterior in-
ternal crests with the anterior external. Its primitive form is
seen in Didelphys, Pelycodus, Pantolambda, and the Amblypoda
generally ; in Centetes and Talpa ; and in its sectorial form, in
Styi^olophus and Oxysena, etc.

Fia, 64. — StypolopJim ivMtim Cope, sTcull two thirds natural size. A Creodont
from the Wasatch Eocene, displaying well the tritubcrcular superior, and the tubercu-
lar-sectorial inferior molars.

The mechanical action of such teeth is as follows : Of course,
it results from the form of the superior molars that the spaces be-
tween them are wedge-shaped, the apex external, the base open-

TRITUBERCULATE TYPE OF MOLAR TOOTH. 361

ing to the palate. The base of the triangular section of the an-
terior part of the inferior molar is interior, and the apex exterior,
and when the jaws are closed this triangular prism exactly fits
the space between the superior molars. The lower heel of the in-
ferior molar receives the impact of the crown of the superior
molar. Thus the oblique edges of the inferior triangle shear on
the edges of two adjacent superior molars. The anterior parts of
the inferior molars, and the superior molars, form an alternate
dental series as distinguished from the prevalent opposed denti-
tion of most Mammalia. In so far it resembles the reptilian
dentition.

This primitive dentition has been modified in two directions,
viz., to form the grinding and the sectorial dentitions. As
already remarked, the superior molars gradually acquire a pos-
terior internal lobe, which produces the quadrituberculate type.
This, lobe, by opposing the anterior internal lobe of the next pos-
terior inferior molar, precludes the entrance of the anterior trian-
gle of the latter between the two superior molars. Hence we find
in the types which possess quadri tubercular superior molars, that
the anterior triangle of the inferior molar is not elevated, if pres-
ent, as, for instance, in Rhinocerus. It is, however, more fre-
quently atrophied, and disappears, contributing to form the in-
ferior quadritubercular molar so well known.

On the other hand, as I have pointed out,* the anterior
internal cusp of the triangle of the inferior molar may be more
developed antero-posteriorly, giving the antero-internal edge of
the triangle much greater obliquity than the postero-internal.
In correspondence with this modification, the superior triangular
molar loses its equilateral character by the more anterior position
of its internal angle, thus elongating the posterior internal side of
the crown. The latter thus fits the corresponding form of the
triangle of the inferior molar, forming with it the shear of the
sectorial tooth.

In a former article, ^^On the Homologies of the Molar Teeth,"
etc., I traced the modifications of the superior and many of the
inferior molars of the ungulate mammals to a parent quadrituber-
culate type. In a subsequent essay f I traced the origin of the

* On the origin of the sectorial tooth of the Carnivora, " American Naturalist,"
1875.

f "Journal Academy Natural Sciences," Philadelphia, March, 18Y4.

362

MECHANICAL EVOLUTION.

inferior sectorial to a primitive five-tubercled, or '^tubercular
sectorial" type. Farther than this I did not go, and made no
attempt to derive the few cases of triangular superior molars then
known, nor the type of the superior sectorial. The revelations of
the Puerco fauna show that the superior molars of both ungulate
and unguiculate Mammalia have been derived from a tritubercular

Fig. 65. — Deltatherium fnndaminis Cope, skull and ramus mandibuli, two thirds
natural size, from the Puerco beds of New Mexico. Fitrs. a, i, c, from one individual.
Fig, d^ from a second animal. Fig. a, right side of cranium ; J, palate from below ; c,
mandible part, from above ; d^ left ramus, outer side. From the Eeport U. S. Geol.
Surv. Terrs., vol. iii.

Original.

type ; and that the inferior true molars of both have been derived
from a " tubercular sectorial " type. Shall we look for the origin
of the latter in a tritubercular tooth also, i. e., tubercular sec-
torial without heel ; and will the crowns of the true molars of the
primitive mammals alternate with, instead of opjDose each other ?
This is a probable result of future discovery.

xiy.

THE ORIGIN OF THE SPECIALIZED TEETH OF THE

CARJSTIVORA.

The specially developed teeth of the Carnivora are the canines
and sectorials. The former are large in many orders of Mam-
malia, and their origin is probably to be sought among the Thero-
morphous reptilia,* as Clepsydrops and Deuterosaxirus, if not in
still lower types. The successive modifications of form which
have resulted in the existing sj)ecialized single lower sectorial
tooth of the FelidcB have been already pointed out.f They were
shown to consist in the gradual obliteration of the internal and
posterior tubercles, and the enlargement of the external anterior
tubercle in connection with an additional anterior tubercle. The
modification in the character of the dentition, taken as a whole,
was shown to consist in the reduction in the number of teeth, un-
til in Felis, etc., we have almost the entire function of the molar
series confined to a single large sectorial in each jaw.

Observation on the movements of the jaws of Carnivora shows
that they produce a shearing motion of the inferior on the su-
perior teeth. This is quite distinct from the sub-horizontal
movement of Ruminants, or the vertical motion of hogs and
monkeys. Examination of the crowns of the sectorials shows
that the inner side of the superior, and the external side of the
inferior, are worn in the process of mastication. The attempt to
cut the tough and stringy substances found in animal bodies is
best accomplished by the shearing of the outer edge of the lower
molar on the inner edge of the external tubercles of the superior
molar, in an animal with simple tubercular teeth. The width of
the mandible is too great to allow the inferior teeth to shear on
the inner edge of the inner tubercles of the superior series. The

* " American Naturalist," 1878, p. 829.

f Cope, "Proceedings Academy Philada.," 1875, p. 22.

PLATE XVIII.

Hycenodon horridus Leidy, skull one half natural size. From the White River formation
of Nebraska. From Leidy's " Extinct Mammalia of Dakota and Nebraska."

ORIGIN OF SPECIALIZED TEETH OF THE CARNIVORA. 365

cusps of both superior and inferior teeth engaged in this process
have developed in elevation, at the expense of those not engaged
in it, viz. : the internal cusps of the same teetli. The atrophy of
the latter can not have been due to friction, since the internal
cusps of the inferior series, which have not been subjected to it,
are reduced like those of the superior sectorial, which have. In-
deed, it is possible that some of the Creodonta, the carnivores of

Fig. 66. — Oxymna lupina Cope, jaws, one half natural size, from the Wasatch beds
of New Mexico. Fig. a, maxillary bone with teeth, from below ; 6, last superior molar,
from behind. Original ; from the Eeport U. S. G. G. Survey W. of 100th Mer., G. M.
Wheeler.

the Lower Eocene, may have been derived from ancestors without
or with rudi mental inner cusps. In any case the effect of use in
lengthening the external cusps appears to have operated in the
Carnivora, as it has done to a greater degree in the Uiigidata ; and
the lateral vertical wear would appear to have resulted in the
blade-form, as transverse wear in the Ungulates has resulted in
the plane grinding surface.

The specialization of one tooth to the exclusion of others as a
sectorial, appears to be due to the following causes. It is to be
observed, in the first place, that when a carnivore devours a
carcass, it cuts off masses with its sectorials, using them as
shears. In so doing it brings the part to be divided to the angle
or canthus of the soft walls of the mouth, which is at the front of
the masseter muscle. At this point, the greatest amount of force
is gained, since the weight is thus brought immediately to the
power, which would not be the case were the sectorial situated
much in front of the masseter. On the other hand the sectorial
could not be situated farther back, since it would then be inac-
cessible to a carcass or mass too large to be taken into the mouth.

The position of the sectorial tooth being thus shown to be de-

366

MECHANICAL EVOLUTION",

pendent on that of the masseter muscle, it remains to ascertain a
probable cause for the relation of the latter to the dental series in

modern Carnivora. Why, for
instance, were not the last
molars modified into sectorial
teeth in these animals, as in
the extinct Hycenodon, and
various Creodontaf The an-
swer obviously is to be found
in the development of the pre-
hensile character of the canine
teeth. It is probable that the
gape of the mouth in the Hyae-
nodons was very wide, since the
masseter was situated relative-
ly far posteriorly. In such an
animal the anterior parts of
the jaws with the canines had
little prehensile power, as their form and anterior direction also
indicates. They doubtless snapped rather than lacerated their
enemies. The same habit is seen in the existing dogs, whose long

F G. 67. — rrooelurvs jalieni Filh., two
thirds natural size. From tlic Phosphorites
of France. From Filhol.

Fig. 68. — Dinidis ajclops^ one half natural size. From John Day Miocene of
Oregon. Mus. Cope. From vol. iii, U. S. Gcol. Surv. Terrs.

jaws do not permit the lacerating power of the canines of the
Felidce, though more effective in this respect than those of the
Hycenodons. The usefulness of a lever of the third kind depends
on the approximation of the power to the weight ; that is, in the

ORIGIN OF SPECIALIZED TEETH OF THE CARNIYORA. 367

present case, the more anterior the position of the masseter muscle,
the more effective the canine teeth. Hence it appears that the rela-
tion of this muscle to the inferior dental series depended originally
on the use of the canines as prehensile and lacerating organs, and
that its insertion has advanced from behind forward in the history
of carnivorous types. Thus it is that the only accessible molars,
the fourth above and the fifth below, have become specialized as
sectorials, while the fifth, sixth, and seventh have, firstly, remained
tubercular as in the dogs, or, secondly, have been lost, as in hy-
enas and cats.

XV.

ox THE ORIGIN OF THE FOOT STRUCTURES OF

THE UNGULATES.

The following considerations have been suggested by a study
of the primitive types of the odd- and even-toed ungulates. I
first, in 1874, recorded the opinion that the Mammalia with a
reduced number of digits were derived from pentadactyle planti-
grade types.* The ungulate order which fulfills this requirement
is the Amhlypoda, and from them, I doubt not, both the Perisso-
dactyla and Artiodactyla have arisen, although not from any of
the genera now known. Both of these great orders display a
regular diminution in the number of the digits ; in the former,
by reduction and extinction on both sides of the third digit ; in
the latter, by reduction and extinction on each side of the third
and fourth digits. Mr. John A. Ryder f has pointed out that
reduction in digits is probably directly related to strains and im-
pacts. He reminds us that the anterior digits are reduced in
Mammalia of unusual scansorial or fossorial powers ; while in
forms which display powers of running, the reduction is seen first
in the posterior feet, which j)ropel the* body much more than the
fore feet. This view is well illustrated in the Perissodactyle
families, the majority of which have the digital formula 4 — 3.

No reason has ever been suggested, so far as I am aware, in
explanation of the fact that one series of ungulates has retained
two digits, and the other only one ; that is, why there should
have been two kinds of digital reduction instead of one kind. In
seeking for an explanation, we will remember that the tarsus in
the odd or single-toed line is bound together by fixed articula-
tions, while in the cloven-footed line it is interrupted by the hinge
between the first (astragalus) and second rows of bones. The
hinge-joint, being more liable to luxation than the fixed articula-

* "Journal Academy Philadelphia," March, 1874.
f "American Naturalist," October, ISY?.

ORIGIN OF FOOT STRUCTURES OF THE UNGULATES. 369

tion, requires a wider basis of support, such as would be furnished
by two divergent digits, rather than by a single central one.

In the early types, w^here the median digits are slender, the
mechanical advantage in favor of the bidigital over the undigital
arrangement is much more obvious than in modern genera. Late
in time, the horse developed the middle digit to such a width as
to form almost as good a support as the bidigital structure. In
the Eocene genera, the slender median digit could not have sus-
tained the weight on a hinge, without great risk of dislocation.

Fig. 70.

Fig. 71.

Fig. 70. — Eight posterior foot of a species of Corypliodon from New Mexico, one
half natural size. From Report Expl. W. of 100th Mer., G. M. Wheeler, iv, PI. ILx.

Fig. 71. — Right posterior foot of the rhinoceros, ApJielops megalodus Cope, from
Colorado, one half natural size. From Report U. S. Geol. Surv. Terrs. F. V. Hayden,
iv, PI. cxxx.

This explanation, it can be said, applies only to the posterior foot.
The posterior foot has, however, led the way in the evolution of
Ungulata, and the fore foot may have followed in accordance
with the law of antero-posterior symmetry in growth. A curi-
ously malformed deer from Mendocino County,' Cal., throws some
light on this subject. It has apparently a single functional digit
on each foot. Examination shows that the posterior foot is bi-
digital, but that the phalanges are fused ; while the anterior foot
24

370

MECHANICAL EVOLUTION.

is perissodactyle, all the digits but the third being rudimental !
Similar evidence is furnished by the genus Anoplotlierium * of the
French Eocene. Its posterior foot is modified artiodactyle, while
the anterior is modified perissodactyle. We may assume from

Fig. 72. Fig. 73.

Fig. 72. — Right posterior foot of ProtoTiippug sejunctus Cope, from Colorado, about
one half natural size. From Eeport U. S. Geol. Surv. Terrs. F. V. Hayden, iv.

Fig. 73. — Eight posterior foot of Foehrotherium labiatum Cope, from Colorado, three
fifths natural size. From Hajden's Eeport, iv, PI. cxv.

these facts, that the posterior foot is more subject to the influ-
ences which tend to produce the bidigital structure than is the
anterior limb.

* Euryiherium Gerv. in the original, a name shown by Schlossev to apply to
Anoplotherium. (Ed. 1886.)

ORIGIN OF FOOT STRUCTURES OF THE UNGULATES. 37I

I suspect that the production of a ginglymus in the middle of
the tarsus has been due to the use of the posterior limb in soft
swampy ground. In the absence of this condition, as in a life on
harder ground than swamp, no ginglymus would be formed.
The action of an ungulate in walking through deep mud is very
suggestive. The posterior foot is bent on the leg, and the antero-
posterior strain of the weight or propulsive force is transverse to
its long axis. In progression on dry land, the impact is in the
direction of the length or axis of the foot. The obvious effect of
a cross strain is to produce by degrees greater and greater mobility
of some articulation. The one which has yielded is that between
the two tarsal rows. Another effect of walking in swampy ground
is to spread the digits apart. As the first digit
of both feet is always of reduced size, there are
practically but four digits to be considered.
The weight falling nearly medially on these,
would tend to spread them equally, two on
each side. Thus the same cause may have been
effective in producing both the artiodactyle
structures. The perissodactyle structure, so
soon as the lateral digits are much reduced,
ceases to be favorable for progression in soft
ground, owing to the liability of the lateral
digits to injury, in following the principal one
into the yielding material, filled with sticks
and other hard debris.

The lowest existing forms of the Artiodac-
tyJa, the Omnivora, are universally swamp
lovers and livers. So, we are told, are the lower
existing Perissodactyla, the tapirs and rhinoce-
roses. The higher types of both orders are
dwellers on plains and in forests. We do not
know the habits of the Eocene Perissodactyla, Colorado, three fifths
but I doubt their having inhabited muddy ^^a^urai size. From
ground to the same extent as the hogs and hip- pf^^xT ^ ^^^° ' ^^'
popotami, the lowest of the Artlodadyla. Now,
in progression on dry land, any pre-existent inequality in the
length of the digits would tend to become exaggerated. Such an
inequality exists in the Amllypoda, the third, digit being a little
the longer. In rapid movement on hard ground the longest toe
receives the greatest part of the impact, even if its excess of

Fig. 74.— Left fore
foot with part of ra-
dius of Poebrotheritim-
mlso/ii Leidy, from

372 MECHAmCAL EVOLUTION".

length is but little. The harder the ground, the larger the pro-
portion of impact it will receive.

The fact that the Perissodadyla did not develojo the solid un-
gulate or equine foot until a late geological jDcriod, or, in other
words, that the orders so long retained the digital formula 4 — 3,
would indicate that it did not adopt a habitat wdiich required
great speed as a condition of safety, so early as the Artioclactyla.

XVI.

ON" THE EFFECT OF IMPACTS AND STRAINS ON
THE FEET OF MAMMALIA.*

The principal specializations in the structure of the feet of the
Mammalia may be summarized as follows :

I. The reduction of the number of the toes to one in the Peris-
sodadyla (horses, etc.), and two in the Artiodactyla (cloven feet).

II. The second hinge-Joint in the tarsus of the Artiodactyla.

III. The trochlear ridges and keels at the various movable
articulations of the limbs. These are as follows :

1. Looking downward —

a, Intertrochlear crests of the humerus.

/?. On the carpal end of the radius.

y. Metacarpals, distal ends.

6. Tibia distally.

e. Metatarsals distally.

2. Looking upward —

a. Radius distally.

j9. Astragalus, edges.

y. Astragalus distally {Artiodactyla).

6. Phalanges (very weak).

The following observations may be made respecting the struct-
ures included under Division III : The trochlear keels which look
downward are much the most prominent and important. Those
enumerated as looking upward are weak and insignificant, or of a
different character from the down-looking ones. The latter are
all projections from the middles of the ends of the respective ele-
ments. The up-looking are generally projections of the edges of
bones. Such are the lateral crests of the astragalus, and the ad-
jacent edges of the cuboid and navicular bones which cause the
distal emargination of the astragalus in the Artiodactyla. The

* Read before the National Academy of Sciences, April, 1881, Abstract. Some
of the points of this paper have already been discussed in the preceding article, but
the present abstract contains additional matter.

374 MECHANICAL EVOLUTION.

proximal ridges of the phalanges are very weak, and the concavities
in the extremity of the radius can not be called trochlear, as they
are adaptations to the carpal bones.

I. The reduction in the number of toes is supposed to be due
to the elongation of those which slightly exceeded the others in
length, in consequence of the greater number of strains and im-
pacts received by them in rapid progression, and the complement-
ary loss of material available for the growth of the smaller ones.
This is rendered probable from the fact that the types with re-
duced digits are dwellers on dry land in both orders, and those
that have more numerous digits are inhabitants of swamps and
mud. In geological history it is supposed that the Perissodactyles
(Figs. 72, 73) originated from the AmUypoda, or primitive Ungu-
lata (Figs. 69, 70), which first assumed terrestrial habits, while
the Artiodadyla (Fig. 74), originating from the same order, long
continued as mud dwellers ; as witness the hippopotami and hogs
of to-day. The mechanical effect of walking in the mud is
to spread the toes equally on opposite sides of the middle line.
This would encourage the equal development of the digits on each
side of the middle line, as in the cloven-footed types. In progres-
sion on hard ground, the longest toe (the third) will receive the
greatest amount of shock from contact with the earth. There is
every reason to believe that shocks, if not excessive, encourage
gi'owth in the direction of the force applied. This is strongly
suggested by the relations between the length of the legs and the
rate of speed of animals ; and the lengths of the teeth and their
long-continued use. Certain it is that the lengths of the bones of
the feet of the Ungulate orders have a direct relation to the dry-
ness of the ground they inhabit, and the possibility of speed which
their habitat permits them, or necessarily imposes on them.

II. The hinge between the first and second series of tarsal
bones in the Artiodadyla may be accounted for by reference to
the habits which are supposed to have caused the cloven-footed
character. Observation on an animal of this order walking in
mud, shows that there is a great strain antero-posteriorly trans-
verse to the long axis of the foot, which would readily cause a
gradual loosening of an articulation like that connecting the two
series of tarsals in the extinct Amblypoda. Any one who has ex-
amined this part of Corypliodon will see that a little additional
mobility at this point w^ould soon resemble the second tarsal joint
of the hogs. In the case of animals which progress on hard

IMPACTS AND STRAINS ON TOE FEET OF MAMMALIA. 375

ground, no such cross-strain would be experienced, and the effect
would be to consolidate by flattening the fixed articulation.

III. The trochleae. These prominences, which form the
tongues of the tongue and groove articulations, exhibit various
degrees of development in the different Mammalia, Those of
different parts of the skeleton coincide in their
condition in any one type of ambulatory Mam-
malia, and so may be all considered together.
This fact suggests strongly that they are all
due to a common cause.

They are all imperfect in the Rodentia and
Carnivora (Figs. 75-77) (except the Leporidce,
which are especially characterized by their great
speed). Among ungulates they are very imjDer-
f ect in the Prohoscidea.
The orders mentioned
all have elastic pads on
the under sides of their
feet or toes. The same
is true of the lowest
types of both the Ar-
tiodactyla and Perisso-
dactyla, the hippopo-
tami and rhinoceroses.
In the Rumina7itia the
trochleae are well de-
veloped (Fig. 80) with
one exception, and that
is the distal metacar-
pal and metatarsal
keels of the Camelidm
(Figs. 79, 81). These
animals confirm the
probability of the keels
being the effect of long-
continued shocks, for
they are the only Euminants which have elastic pads on the in-
ferior sides of their digits.

That these processes may be displacements due to shocks long
continued, is rendered probable by the structure of the bones
themselves. (1) They project mostly in the direction of gravity.

Fig. 75. Fig. 76. Fio. 78. Fig. 77.

Fi^. 75, Distal extremity of tibia of Amhlyctonus
sinosus Cope. Fig. 76, Distal extremity of tibia of
Oxycena morsitans Cope. Both flesh-eaters, and two
thirds natural size. From Eeport Expl. and Surv. W.
of 100th Mer., G. M. Wheeler, iv, Pt. ii.

Fig. 77, End of tibia and astragalus of Archcelurus
debilis. Fig. 78^ Femnr of jyimravusffomphodus. Car-
nivora ; one third natural size. Mus. Cope.

376

MECHAmCAL EVOLUTION".

Constant jarring on the lower extremity of a hollow cylinder with
soft (medullary) contents and flexible end walls, w^ould tend to a
decurvature of both inferior and superior adjacent end walls. If

the side walls are wide and resistant, the
projection will be median, and will be
prolonged in the direction of the flexure
of the joint. The groove of the astraga-
lus deepens coincidently with the increase
of digitigradism, showing that, while it

is primarily pro-
duced by shocks,
it is extended
fore and aft by
the repeated flex-
ure of the ankle-
joint. (2) They

Fig. 7U.

Fig. 80.

Fig. 81.

Fig. 79, Part of anterior foot of Procamelus occidentalis from New Mexico. Oiig-
inal from Eeport of Capt. G. M. Wheeler, vol. iv, Pt. ii.

Fig. 80, Metacar]~>als of Cosoryx furcatus from Nebraska, two thirds natural size,
c, anterior face ; ft, posterior ; c, proximal end ; d^ distal end.

Fig. 81, Left fore foot with part of radius of Poehrotherium tilsoni Leidy, from
Colorado, tiiree fifths natural size. From Hajden's Eeport, iv.

fit entering grooves of the proximal ends of corresponding bones.
These will be the result of the same application of force and

IMPACTS AND STRAINS OX THE FEET OF MAMMALIA. 377

displacement as the protrusion of tlie inferior, commencing with
a concavity (Eleplias) ; becoming more concave (Fig. 77), and
becoming finally a groove. (3) When the dense edge of a bone,
as in the case of the lateral walls of the astragalus, is presented
upward, a groove is produced in the down-looking bone ; e. g.,
the lateral grooves of the distal end of the tibia. (4) When the
inferior bones are the denser, the superior articular face yields ;
e. g., the distal end of the radius to the first row of carpals
(Fig. 81).

(5) The metapodial keels commence in the lower types on the
posterior side of the distal extremity of the bone. This is j^artly
due to the presence there of a pair of sesamoid bones which, with
the tendons in which they are developed, sustain and press on the
lateral parts of the extremities, and leave the middle line without
support (Figs. 79-81).

PART IV.

METAPHYSICAL EYOLUTIOIsr.

XVII.

THE EVOLUTIONARY SIGNIFICANCE OF HUMAN

CHARACTER.*

The complicated constitution of the human mind is well im-
pressed on the investigator as he seeks to understand the origin
of any one of the many different types of character which come
before him. The number of possible combinations of its numer-
ous elements, each of which present developmental phases, is
necessarily very great. The species of human minds, as one may
properly term them, are probably as numerous as the species of
animals, as defined by their physical structure. As in the case
of anatomical species, however, analysis of the mind reduces its
many details to a few leading departments. Although the classi-
fication of the elements of the mind is a classification of func-
tions, it is, if correct, a sure index of the classification of struct-
ure also ; of the grosser and more minute structure of the brain,
principally of the gray matter.

The division of mental activities into three primary divisions
is generally admitted. These are : the emotions, the intellect, and
the will. The emotions include the likes and dislikes, or the
tastes, and their strongest forms, the emotions and the passions.
The intellect includes those powers which rearrange the experi-
ences in an order different from that in which they enter the
mind. This new order may have sole reference to questions of
liking and disliking, and is then a product of the imagination ;

* The present article is in continuation of the previous one on the Evolutionary
Significance of Human Physiognomy, published in the "Naturalist" of June, 1883.

EVOLUTIONARY SIGNIFICANCE OF HUMAN CHARACTER. 379

or it may be a result of experience of the laws of pure necessity,
without regard to questions of taste ; then it is a process of rea-
son. The will, properly so called, is the spontaneous power of
the mind by which the other processes are originated, directed
or restrained. The range of the will, and even its existence, are
questions of dispute.

Below and behind these mental activities lies seiisihility or
consciousness, in its forms of general and special sensation ; that
is, touch and hearing, taste, smell, sight, and the muscular sense,
with many others, concomitants of both health and disease. It is
well understood that these primitive mental qualities are more or
less developed in animals in which the more purely mental func-
tions are rudimental. The doctrine of evolution teaches that
from this class the higher activities of the mind have been devel-
oped, during long ages, through the agency of memory. The
nature of the present essay only permits a casual reference to the
astonishing character of memory, and the remark that its phe-
nomena demonstrate most clearly, of all others, that mind is an
attribute of some kind of matter.

If we now consider these natural divisions of the mind as they
present themselves in the combinations which we call human
character, we shall observe a variety in the mode of their action
which pervades all divisions alike. These variations fall under
two heads, those of quantity and of quality.

Thus as to quantity ; one human mind may present a greater
amount of intellectual than emotional activity ; of imaginative
than rational intellection ; of affectionate than irascible emotion ;
of gastronomic than musical taste, etc., etc. The quantity here
indicated is probably an index of the proportion of brain tissue
devoted to the functions mentioned. The intensity or force of the
action is a matter of quality.

Of qualities the variety is much larger. They are often paral-
lel to those of inorganic force, and suggest the same kind of modi-
fications of the material bases as those which affect the latter.
Two prominent qualities are fineness and coarseness. Fineness
observes and uses detail in both rational and emotive acts, and is
essential to the precision of finish. Coarseness neglects detail,
but deals with the gross of things, and is sometimes accompanied
by largeness of quantity. When it is not, the result is not good.
Fineness is, on the other hand, often associated with smallness. It
is a more feminine attribute, while coarseness is more masculine.

380 METAPHYSICAL EVOLUTIOK

Another pair of antitlietic qualities are intensity of action and
the reverse. This probably means that a given bulk of brain
tissue produces (i. e. , converts) a greater amount of energy in a
given time than an equal bulk of non-intense tissue.

The speed or rate of action in time, and its opposite, slowness,
are related to the last-named qualities, but are not identical with
them. Thus growth of the mind always witnesses a diminution
in the rate of action, but an increase in intensity.

Tenacity of mental action is a very marked character, and of
great importance. It signifies the persistence of mental action,
or mental endurance, and may characterize the entire mind, or
only a part of it. Its opposite, seen in changeability, desultori-
ness or fickleness, may also characterize all or a part only of the
mind. According as it characterizes the intellectual or emotional
departments are its exhibitions most varied, though they probably
have a common histological basis.

Impressihility and stolidity express antitheses of character
which are seen every day. The term impressibility is used as
identical with irritability, and is preferred, because the latter has
special physiological and popular meanings, some of which are
only among its phases. These qualities are apt to pervade the
entire mental organism, although, like others, they may char-
acterize a part only. Impressibility is obviously a condition of
tissue, since it varies greatly with physiological conditions in the
same person. Its exhibitions in the department of the emotions
may be confounded with strong development of the emotions
themselves. A moment's thought, however, shows that easy ex-
citation of emotion is a different thing from energy of emotion,
and is often found apart from it. Impressibility of intellect
shares with tenacity a leading position as an attribute of a first-
class mind, and the combination of the two forms a partnership)
of superior excellence.

I may mention here a quality whose absence is pathological,
and hence does not properly enter the field ; this is tonicity. In
its normal condition, every organ should be supplied with suffi-
cient nutriment or energy to insure the occupation of its entire
mechanism. Anything short of this is followed by poor work.
Debility of mental action in the emotional department is seen in
abnormal irritability, such as peevishness or *^ spooning" ; and in
the intelligence, in absence of mind and blundering; and in both,
in general frivolity.

EYOLUTIOXARY SIGNIFICANCE OF HUMAN CHARACTER. 381

Eeturning to the primary elements of mind, we may examine
their divisions with reference to the question of growth. To be-
gin with the perceptions, there are great diversities in the acute-
ness of the general and special senses, and greater and less sus-
ceptibilities to physical pleasure and pain. In the important
representative faculty, memory, the ditferences between people
are great. As perception as well as thinking involves a certain
amount of structural change, it is evident that susceptibility or
impressibility of the senses, which is the first stage of memory,
signifies ready metamorphosis of tissue. Unimpressibility, which
impedes memory, is a consequence of resistance on the part of
tissue to the usual stimuli. Hence the effect of " sights, sounds,
and sensations " is greatest in childhood, and the memory is most
impressible, for at that time the nervous tissue is undergoing con-
stant change, and nutrition, being in excess of waste, constantly \
presents new material to be organized. And I may here refer to
the general truth, that consciousness of all kinds is the especial
and distinguishing attribute of life as distinguished from death
or no life.* Whatever other phenomena we may be accustomed
to regard as "vital," are only distinguishable from inorganic
motion or force, because they primitively took their form under
the guidance of consciousness, and are hence, so to speak, its
children. With the perfect working of most of the mechanism of
the body, consciousness no longer concerns itself, although it may
speedily do so in pathological conditions. This prerogative is
now restricted to the nervous system, and to certain parts of it ;
the one which is, histologically speaking, the most generalized of
the systems. And it is quite consistent with the '^^ doctrine of
the unspecialized," that nervous tissue in its unfinished state in
childhood should be more impressible to stimuli than at later
periods of life. But this statement requires this modification,
that there is a stage of imperfection of mechanism which does not
display high sensibility, as, for instance, in the earliest infancy.
With age sensibility gradually diminishes.

Next in order of appearance in growth are the emotions. It
is true that some of these are not fully developed until long after
the appearance of many or all of the intellectual faculties ; but it
is also true that their full development precedes that of the intel-
lect, in so far as they are developed at all. The primitive condi-

* "The Origin of the Will," " Penn Monthly," 1877, p. 440.

382 METAPHYSICAL EVOLUTION.

tion of the emotions is that of appetites. The first of these in
the necessary physiological order, and hence in time, is the appe-
tite of hunger. Second in order in the history of life, but not in
the growth of individuals, is the instinct of reproduction, such as
it is in animals that only multiply by fission. Very early in evo-
lution the emotion of fear must have arisen, and it is probably
the immediate successor of hunger in the young of most animals.
Anger appears as early as the mind can appreciate resistance to
its first desires, and no doubt followed as third or fourth in the
history of evolution. The rudiments of parental feeling would
follow the origin of reproduction at a considerable interval of
time. One of the latest of the instincts to appear would be the
love of power ; while later still would be the emotions of rela-
tivity (Bain), because they are dependent on a degree of mental
appreciation of objects. Such are admiration, surprise, and won-
der. These, as well as all other consequences of inherited intel-
lect, appear earlier in infancy than they did in evolution, as may
be readily understood.

Of these instincts and emotions, it is to be supposed that hun-
ger remains much as it has ever been. The reproductive instinct
' has, on the other hand, undergone the greatest modifications.
Sex instinct could not have existed prior to the origin of the
male sex, which must be regarded in evolution as a derivative
from the female. Hence it is probable that the parental instinct
preceded the sexual in time. These two instincts being the only
ones which involve interest in individuals other than self, furnish
the sources of sympathy in all its benevolent aspects. Hence it
has developed in man into the powerful passion of love ; into
affection and charity in all their degrees and bearings. Fear be-
ing, as Bain shows, largely dependent on weakness, has varied in
development in all times, but must be most pronounced in ani-
mals of high sensibility, other things being equal. Hence its
power has, on the whole, increased until it probably reached its
extreme in the monkeys or the lowest races of men. Increasing
intelligence of the higher order diminishes the number of its
occasions, so that it is the privilege of the highest types of men
to possess but little of it. The earliest of the emotions of rela-
tivity to appear in time has probably been the love of beauty ;
how early it may have appeared it is difficult to imagine. Sur-
prise and wonder, as distinct from fear, one can only conceive as
following an advanced state of intelligence.

EVOLUTIONARY SIGNIFICANCE OF HUMAN CHARACTER. 383

Thus in psychology as in physiognomy,* the palcontological
order of development is somewhat different from the embryologi-
cal. I might compare the two orders as follows :

PAL EONTOLOGIC AL.

EMDRYOLOGICAL.

Hunger.

Reproduction.

Fear.

Anger.

Beauty.

Parental instinct.

Wonder.

Sex.

Power.

Admiration.

Beauty.

Pity.

Wonder.

Sex.

Parental instinct.

The qualities enumerated in the first column follow each other
directly in order from the simple to the complex. In the second
column this order is disturbed by the earlier appearance of the
derivative emotions, beauty, wonder, admiration, and pity, or be-
nevolence, and the later appearance of the simple emotion of sex.
Thus in psychological as in other evolution, some of the products
of development appear earlier and earlier in life in accordance
with the law of acceleration.

The intelligence has already been considered under the two
heads of the imagination and the reason. The action of the im-
agination, unmixed with the exercise of reason, is chiefly to be
seen in the creative fine arts, as distinguished from the imitative,
the mechanic, and other arts. The musician, the painter, the
sculptor, the poet, the novelist and the playwright, so far as they
are not imitators, present the best illustrations of the work of the
imagination. It is a faculty which must be very little developed
in the animals below man. They occasionally make mistakes in
the nature of objects, and suppose them to be other than what
they are. Thus the Antilocapra supposes the Indian disguised
with a skin and horns to be one of his own species, and suffers
the penalty. But this is a most rudimental act of imagination, if
it be not mere curiosity.

The reason, properly so called, begins in its lowest grades with
the simplest re-arrangement of the objects of sense and memory,
in accordance with some principle of relation. As the principle
or standard of relation varies, so does the intellectual process. If

*" Naturalist," 1883, p. 618.

384 METAPHYSICAL EYOLUTION".

the process be discovery, or the enlargement of knowledge, many
experiences (or hypotheses) will be successiyely encountered and
tested, and appropriate generalizations reached (inductions). If
the process be to accomplish the practical ends of life by use of
well-known means, the intellect uses the customary rules of action
as standards, be they moral or mechanical, financial or political,
and attains its deductions and applications. These two types of
intellect are strikingly distinct, and produce the most diverse con-
sequences. The inductive type is the most generalized, and hence
callable of the largest growth and adaptability, and the widest
range of thought. The deductive is the more specialized, the
more ^^ practical," but less capable of growth or general thought.
Its most remarkable exhibitions are seen in the skill with which
some men conduct the game of chess, and corresponding enter-
prises in real life. Also the ingenuity of mechanical invention,
and the wonderful rapidity of calculation which some minds dis-
play. In intellectual as in many other vital phenomena, the facil-
ity once developed, the active process is often unaccompanied by
consciousness in many or even all of its stages.

Rapid and exact control of the muscles in obeying the direc-
tions of the mind is essential to the practice of many arts, espe-
cially to that of the musician. This accomplishment is acquired
through the medium of the conscious mind, and may be regarded
simply as the reflex of impressions made on the senses directed by
some simple rule which has been impressed on the memory. The
often surprising results involve the exercise of a very simj^le phase
of intellection.

The appearance of the rational faculties in time, may be esti-
mated by their relative development in the existing divisions of
animals whose period of origin is known or inferred. The ani-
mal mind is capable of simple forms of induction and deduction,
and sometimes acquires considerable artistic skill. Bees, ants and
spiders display these in varying degrees, and their antiquity is
probably co-extensive with that of the known sedimentary rocks.
The supposed Ascidian ancestors of the Vertebrata, and even the
lowest vertebrate (Branchiostoma), display far less intelligence than
the articulates mentioned, which are really lower in the scale of
organic types. From such unpromising sources did the noble verte-
brate line descend. It is probable that the inductive act preceded
by a little the deductive in time, as it does in logical order. But
the elaboration of these powers was doubtless long delayed ; for

EVOLUTIONARY SIGNIFICANCE OF HUMAN CIIxVRACTER. 385

untold ages they involved nothing more than the discovery and
application of general principles of the simplest kind ; such as the
customary sequence of natural phenomena, and the anticipation
of their operations, as, for instance, in the laying up of winter
provisions. Occasionally deductive application of an old rule to a
new case would arise, as in that of the Mygale spider which was
observed by Dr. McCook to substitute cotton for her own silk for
the lining of her nest. The development of the rational faculty
has been rather in quantity and quality, than in the nature of its
constituent parts. I may remark, however, that the embryological
order is here again different from the paleontological. Inherited
aptitudes, as for music, calculation, etc., precede, in children, any
considerable powers of thought, while the order of development of
the race has been the reverse.

As regards the appearance of the qualities of mind already
mentioned, which depend on character of tissue, it is difficult to
present an order which shall be generally true. Our ignorance
of the subject is profound ; nevertheless observation of animals
and men leads to the following conclusions : First, the primitive
mind is negative, unimpressible, and little sensitive. In evolution,
sensibility has been developed under stimuli, and diminished by
disuse and repose. The energy of high-strung sensibility has prob-
ably ever won for its possessors success in the struggle for existence,
and more or less immunity from the pains which stimulate to ac
tion.* It is true that the non-aggressive and ever-harassed Her-
bivora have developed the higher brain structure. The inferiority
of brain type of the Carnivora is a well-known fact of present and
past time. The early ruminants were smaller than the contempo-
rary flesh-eaters, and therefore subject to the greatest risks. The
best-developed brains, those of the Quadrumana, have been devel-
oped in still more defenseless animals, who in their arboreal life
have been confronted by still more complex conditions.!

Impressibility or sensitiveness has evidently been the means of
acquisition of some of the other qualities mentioned. Thus inten-
sity may have resulted from active use accompanied by vigorous
nutrition, and the consequent construction of compact force-con-
verting tissue. Rapidity without intensity must also result from

* " The Relation of Man to the Tertiary Mammalia," "Penn Monthly," 1875.

f Mr. C. Morris very reasonably regards the social life of these animals as the

source of their development of intelligence. See "American Naturalist," June,

1886. (Ed. 1886.)
25

386 METAPHYSICAL EVOLUTION.

exercise, with a less yigorous construction of tissue. Fineness and
tenacity, on the other hand, can not be regarded as being so much
produced by use as by very primitive conditions of tissue. Ee-
straint under ]3ressure might produce fineness. Long-continued
freedom from sudden changes, under pressure, might account for
the origin of tenacious tissue. As to quantity, deficiency or diver-
sion of nutritive energy or material must produce smallness, and
the reverse condition, largeness.

These qualities impress themselves on the external as well as
the internal organization, and can be more or less successfully dis-
cerned by the observer. I reserve the question of physiognomy to
a later article, and here consider only the evolutionary bearings of
character itself. As in physiognomy, we may arrange the facul-
ties and their qualities under the two heads of ancestral and embry-
onic, or that of the species and that of the individual. The order
of succession is the same in both kinds of development.

SPECIES. INDIVIDUAL.

Indifference. . Indifference.

Einotions. Emotions.

Intellect. Intellect.

a. Imagination. a. Imagination.

b. Reason. b. Beaso7i.

It is not practicable to go farther than this into the order of
evolution of characteristics. There is probably little uniformity
of sequence other than that I have already pointed out under the
head of the emotions.

As a complex outcome of the emotional and rational faculties
must be now mentioned the moral sense, or the sense of justice.
It consists of two elements, the emotion henevolence, and the ra-
tional power of discrimination or judgment. The former fur-
nishes the desire to do what is right to a fellow-being. Without
the aid of reason, it is benevolence, not justice, and may often fail
of its object. The rational element has acquired from experience
a generalization, the law of right. It perceives what is most con-
ducive to the best interest of the object of benevolence in his rela-
tion to others or to society, or whether he be a proper object of
benevolence at all. By itself, this quality is absolutely useless to
mankind. When it guides the action of human symj^athy, it dis-
plays itself as the most noble of human attributes. Many animals
display sympathy and benevolence, but justice has not yet been
observed in anv of them. Hence it has been said that it can not

EVOLUTIONARY SIGNIFICANCE OF HUMAN CHARACTER. 387

be a derivative faculty, but is '^intuitive" in man. The objec-
tion to this view is its great variability and occasional entire ab-
sence in man, individually and racially. It is the last to appear
in individual growth, as it has doubtless been in the order of evo-
lution, of mind.

I now devote a little space to the discussion of the distribution
of these qualities in races and sexes.

As regards the relative preponderance in action of the emotive
and intellectual faculties, it is an axiom that in the great majority
of mankind, apart from the necessities imposed by the simple
physical instincts, it is a taste or an affection or an emotion that
lies at the basis of their activities. Perhaps the most universal is
the affection of sex. Given two types of rational beings who are
objects of admiration and of pleasure to each other, each of whom
desires to possess the other, and who therefore employs many de-
vices to please and attract the other, and we have an effective agent
of general development. Then the parental, and especially the
maternal, affections arouse and direct many labors. Fear of suf-
fering and death is at the basis of many others. The love of power
or of possession, including ambition, is a well-known stimulus.
The love of beauty is a strong motive in many persons. The
pleasure derived from the exercise of the intelligence is a sufficient
motive for a life-work in a comparatively small number of persons.
These are the artists and the scientists ; but it is far from being an
unmixed motive in many of them.

Intellectual motives, however, enter into association with the
affectional in many instances, as, for example, in the profession of
teaching. But it is as guide and agent in the accomplishment of
the main ends of life that the intellect, especially the reason, has
its great field, and displays itself in an endless variety of ways.

If we now survey men as we find them, it is a general truth
that it is in the male sex that the greatest proportion of rational
method is to be found, and in the female the greatest proportion
of the affectional and emotional. As we descend the scale of
humanity, the energy and amount of the rational element grows
less and less, while the affectional elements change their propor-
tions. The benevolent and sex elements diminish in force more
rapidly than the other sentiments, but it is probable that all the
emotions are less active in savages, excepting those of power and
of fear. In the lowest races there is a general deficiency of the
emotional qualities, excepting fear, a condition which resembles

388 METAPHYSICAL EVOLUTION.

one of the stages of childhood of the most perfect humanity. To
this must be added revenge, where hatred may be re-enforced by
several other sentiments, with a feeble perception of equivalent
suffering or punishment, which may or may not be just. The
pleasure of muscular exercise is greatly developed in people of out-
door habits.

The order of the appearance of the intelligence is nearly de-
pendent on the development of the powers of observation. In
most savages these are very acute, and vary according to the na-
ture of the environment which impresses them. The character
of most civilizations tends to diminish the power of the ]3ercep-
tive, while the higher departments of imagination and reason are
enlarged. The imagination reached a high development before
reason had attained much strength. With the exception of a few
families, the intelligence of mankind has, up to within two or
three centuries, expressed itself in works of the imagination.
When exact knowledge first began to be cultivated, it was in the
department of astronomy, where the least precision was attain-
able, and where the greatest scope for the imagination is to be
found.* Next in time metaphysics was the throne of learning, a
field in which much may be said with the least possible reference
to the facts of observation. With the modern cultivation of the
natural and physical sciences, the perceptive faculties will be
restored, it is to be hojoed, to their true place, and thus many
avenues opened up for the higher thought-power of a developed
race. Thus it is that in the order of human development there
is to be a return to the primitive powers of observation, without
loss of the later acquired and more noble capacities of the intellect.

The relation of the qualities of impressibility, fineness, inten-
sity, speed and tenacity, to our development in time, may have
been as follows : Impressibility of mind is no doubt an embryonic
character of ^' retardation," parallel to, and probably a consequence
of, the retardation which is also expressed in the human skull and
face. The preponderance of the osseous and nutritive elements
over the nervous is the usual accompaniment of non-impressi-
bility, and vice versa. Hence this quality is of late origin in the

* The governments of antiquity required the knowledge of the Chaldean astrono-
mers as important to the success of their undertakings, and the governments of
Europe and America were, for a long period, more liberal in their support of as-
tronomy than any other science. At present, however, geology shares in this aid,
and to a less degree botany and zoology.

EVOLUTION"ARY SIGNIFICANCE OF HUMAN CHARACTER. 389

history of the Vertebrata and of man, and is most developed in
the young, and better developed in women than in men.

Tenacity has an opposite significance, being an especial charac-
teristic of maturity in the human mind. Hence it may have been
more general in early ages than at present, but could have little
value so long as the mind remained small in quantity. Curiously,
it is a quality which may co-exist with a good deal of impressibility.

Fineness can only be a quality of full development, and is
totally independent of the other qualities. It is unknown among
savages, and is developed apj)arently in a few animals. Of inten-
sity it is difficult to say much definitely. The nervous operations
of animals often display the highest degree of this quality, and it
is not unlikely that its appearances differ as much in savages as
in civilized people. Its importance in mental action depends of
course on the kind and amount of mental function which exhibits
it. The same may be said of speed. The faculties which exist
are more or less affected by it. In the well -formed reason it is an
important characteristic, and a special form of development.

Having gone as far into the origin and developmental relation
of mental functions and qualities as the nature of this sketch jier-
mits, I refer briefly to the stimulus to their growth ; always re-
membering that the percentage of inherited qualities is much
larger in a given character than that of acquired ones. On this
head one word expresses a good deal, and that word is use. No
truth is better known than this one, that mental faculties develop
with use more rapidly than those of any other organ of the human
body. Brain and nerve are apparently the most plastic of all tis-
sues ; the one which retains the properties of the primitive pro-
toplasm, multiplied and intensified a thousand fold. It has al-
ways been the seat of creation, throwing off its " formed matter "
in useful directions. It is still doing so ; and in the human
brain, ever creating itself, is in addition the seat of a new creation,
which it executes through its instruments, the other organs of
the body. Hence the greatest sin against the brain is idleness,
or disuse. The brain activity of to-day is an indication of health
and happiness beyond what the world has seen hitherto.

The greatest stimulus to exercise of the brain is human soci-
ety. Hence the greatest developments of mind have always been
in the centers of population. Whatever may be the passive vir-
tues of country life, it is the cities that furnish both the stimulus
and the field for the triumphs of mind.

XVIIL
CONSCIOUSNESS IN EVOLUTION.*

I. PRELIMIKAKY.

The evidence of what is termed ^^ design " in the structure of
beings exhibiting life, is often appealed to by one class of think-
ers, as proving the intervention of a personal Deity in the crea-
tion of such ; and the same feature exhibited in the movements
of living creatures is regarded by metaphysicians of a similar class
as an indication of their possession of a power of choice, or " free
agency," at least in the case of man. The opposing school, of
whom Professor Bain may be selected as an example, believes that
designed acts are without an element of freedom, but are simply
performed in obedience to stimuli of various kinds, motion fol-
lowing stimulus as inevitably as effect succeeds cause in the non-
living world. The evolutionists attempt to explain design in
structure through the operation of the Darwinian law of the
*^ survival of the fittest," showing that only those beings whose
organization displays that adaptation to use in relation to its sur-
roundings, which is termed '^design," could possibly continue to
exist. It is justly urged against this reasoning that it attempts
no explanation of the origin of such structures. Another school
of evolutionists have therefore maintained that such structures are
due to the effect of effort, i. e., stimulus or use, exerted by the
living being on its own body, and that the design thus displayed
is an expression of the intelligence at some time possessed by itself.

So long as there is any probability of the last explanation
proving valid, it will be important to examine into the questions
of metaphysics which it necessarily involves. The investigation
is indeed but the necessary projection of those which have re-
sulted in satisfying the great majority of biologists of the reality
of evolution, or of the fact of the descent of existing living beings,

* A lecture delivered before the Franklin Institute, Philadelphia, February, 1874.

CONSCIOUSNESS IN" EVOLUTION. 391

species by species, order by order, and class by class, from others
which have preceded them in time. Clearly, then, we enter the
question by considering the nature of movements of plants and
animals in relation to the stimuli which are supposed to call
them forth.

II. THE UNCONSCIOUS.

A true study of metaphysics necessarily has for its objects
plants, animals, idiots, and infants, as well as healthy men ; never-
theless, necessity compels us, in discussing the question, to dwell
on our own experiences as a sine qua non. Now experience, in a
general sense, includes not only the memory of our conscious acts,
but a knowledge of our unconscious ones, and to the latter espe-
cial attention must be directed, since they are most readily over-
looked. The marvelous character of memory can not be too
much considered. Of the millions of impressions which the mind
has received and registered, in the course of a lifetime, but one
can be clearly present in consciousness at one time. The remain-
ing millions are not lost ; they are stored, each in its apj^ropriate
place, to be sprung into consciousness when the apj)ropriate
suggestion presents. How much more vast, from this point of
view, is the unconscious mind than the conscious ! But the
phenomenon is not confined to memory. Who that has ever at-
tempted the digestion of a subject which includes a mass of de-
tails, is not acquainted with the unconscious activity of the mind
in classification ? How frequently a question involving many
parts, is, on the first reception of the constituent facts, all con-
fusion ; but in time displays its symmetry clearly to the con-
sciousness, every part in its proper place, and that with little or
no further attention having been devoted to it. It is indeed proba-
ble that the every-day process of inductive reasoning is conducted
in unconsciousness on the part of the subject. Induction con-
sists in the generalization of some quality as common to a great
number of objects of memory ; a greater or smaller number of
other qualities being neglected in the process. When this act is
performed voluntarily, one or many qualities are successively
passed in review before the mind — each one being in its turn im-
pressed on the perceptive centers — so long as it is the object of
inquiry, the others being excluded from consciousness for the
time being. It is simply a process of classification, and when per-
formed in consciousness, constitutes "experiment." But when

392 METAPHYSICAL EVOLUTION".

no generality is anticipated, and its existence is unknown, it often
hajjpens that sucli generalization becomes known or rises into con-
sciousness, without the bestowal of effort in classification of the
objects to which it refers. The impressions consciously received
have been arranged out of consciousness, and when revived into
consciousness display an order wliich was not previously known
to exist. It is in the latter way that the '^23ractical man " "finds
out " the rules by which, as by an instinct, he regulates his inter-
course with the world. He often can not explain the reasons of
their truth, nor does he know how he came by them, being gen-
erally content to call them the results of ^' experience." In some
persons they are so feebly expressed in consciousness as to be called
*' feelings" ; and many experiences or repetitions are sometimes
necessary to impress on us the importance of these mental prod-
ucts before we are willing to follow them in action. '^ Strength
of mind " is an expression applied to a high degree of this uncon-
scious reasoning ; expressing the extent of ground the process
covers continuously, as well as the exactitude of its results. The
experimental investigator, on the other hand, performs this work
deliberately, and is acquainted with the processes ; he is, there-
fore, at first more confident of his results. And we observe here,
in passing, that a rule once discovered is as readily retained in
the cells of the unconscious as is the memory of a simple object
or event.

Another form of unconscious cerebration is seen in deductive
reasoning, which employs rules already discovered in application
to new cases. Calculating prodigies are a case in point. It is
well known that those persons who have from time to time ap-
peared possessed of the power of calculating with enormous num-
bers with marvelous rapidity, have never been able to explain the
process by which they reach their conclusion, nor are they con-
scious of going through the steps involved in the calculation they
perform ; and it has been said that great calculators have rarely
been great mathematicians.

The explanation of these phenomena is not far to seek. In
simpler forms it is presented to us every day. Thus it is an easy
matter to read with but little consciousness of the process, and no
recollection of the subject-matter of what is read. Most manual
operations can be performed while the consciousness is occupied
with other objects.

If these be facts of human experience, how much more likely

CONSCIOUSNESS IN EVOLUTION. 393

are they to be true of animals ? If man be unconscious of the
process during the performance of some of his most complex acts,
how much more probable is it that animals are so while pursuing
the narrower circle of their simpler ones ? Yet animals are not
devoid of consciousness ; indeed, it is scarcely credible that any
one should deny to them consciousness, after exjoerience in their
education.

But let these automatic acts be ever so simple or complex, it is
here claimed that they could not have origmated out of conscious-
ness. Whatever we call voluntary acts in ourselves undoubtedly
have to be learned. The acquisition of the primary act of walking
is accomplished by a slow and painful education ; while knitting
and other manual exercises necessarily require preliminary train-
ing, some of shorter, others of longer, duration. This is true of
such voluntary acts as we perform most readily automaticall}^, and
such as might be supposed to be most probably acquired by heredi-
tary transmission, as for instance speaking. The case is the same
with animals. All those services which are useful to us, or tricks
which amuse us, are acquired at the expense of training, which
involves a system of stimuli, consisting of rewards and punish-
ments, as in our own species. Is there any reason to suppose that
those habits which we observe them to possess in a state of nature
have had a different origin ?

It is incontrovertible that a regular succession of muscular
movements may be committed to memory as certainly as a color
or a shape, and that a change of brain substance, such as causes
the retention of the simple impression, is also involved in the
retention of the complex. When this machinery is completed,
through the repetition of conscious stimulus, it works thenceforth
without necessary intervention of consciousness. The conscious-
ness may then be engaged in fresh acquisitions, accomplishing new
organizations, thus accumulating a store of powers. Once organ-
ized, these powers are at the disposal of their possessor, yet the
organized machine will at some time undergo change, if not more
or less frequently used. Without use it may indeed finally disap-
pear, showing that the caj)acity for organization is identical with
a facility of disorganization.

III. THE ORIGII^ OF AUTOMATIC MOYEMEJ^TS.

Is any habit originated in unconsciousness ? Those who affirm
this proposition point to the movements of plants in the extension

394 METAPHYSICAL EVOLUTION.

of their tendrils, and the closing of some sensitive leaves ; the
timely expansion of the down of the Asclepias seed, and the in-
sect-catchinof habits of Brosera and Dioncea. No one surely
attributes consciousness to these. And there are many similar
movements in animals which are as thoroughly unconsciously
performed as are those of plants, from the first moment of the ani-
mal's birth : as, for instance, the involuntary activities of the cir-
culatory and digestive systems, etc. Did these originate in con-
sciousness or unconsciousness ? The answer to this question
constitutes the key to the mysteries of evolution, and around it
the battle of the evolutionists of the coming years will be fought.

It may be asserted at the outset that those habits whose origin
we have had the opportunity of observing in ourselves and in other
animals were certainly acquired in consciousness, and that we do
not believe that they could have originated out of it. The stimuli
to action are divided into the two general classes of pleasures and
pains, and each stimulus is potent in proportion to the intensity
with which it is consciously apprehended. If many and complex
acts may be performed automatically, through the organization of
special machinery in the gray matter of the brain, it is altogether
reasonable that similar powers should be found to be conferred on
gray nervous tissues in parts of the body which are no longer seats
of consciousness. It is well known that the spinal cord of the head-
less frog responds to stimuli, in the vigorous muscular contractions
of the limbs which follow the application of acid to the skin. So
the ganglionic centers of organic life respond to their appropriate
excitants ; the various glands of the digestive system discharging
their contents into the ingesta at the proper moment, conscious-
ness having no share in the proceeding. These phenomena are
more readily explained on the theory of endowment than on that
of physical movements ; since by means of the former the evident
design in the movements is accounted for, while the latter gives us
no clew to this characteristic feature of these and all other vital
processes.

The lowest form of consciousness is common sensibility ; and,
judging by the resemblance between our own experience and that
of the higher animals, the lowest of animals also are not devoid
of this quality. The structureless jelly of Rhizopods, such as
Amoebas, Gromias, etc., evidently selects its food with regard to
its nutritious qualities, in most instances preferring diatoms and
desmids to sand and other innutritions substances. Its acquisi-

CONSCIOUSNESS IN EVOLUTION. 395

tions in knowledge of articles of food can only be accounted for
on the hypothesis of original, pleasurable or painful, conscious-
ness of the effects of external and internal contact with these sub-
stances, and retention of the impression in unconsciousness. The
impression reviving on the recurring of a similar contact, the sub-
stance is accepted or rejected as the former sensations were pleas-
urable or painful. And this is not incredible, if, as the researches
indicate, the structure of the protoplasm of these creatures is of
the same type as that of the bioplastic bodies of the gray tissue of
the brain.

in accordance with this view, the automatic *^ involuntary "
movements of the heart, intestines, reproductive systems, etc.,
were organized in successive states of consciousness, which con-
ferred rhythmic movements, whose results varied with the ma-
chinery already existing and the material at hand for use. It is
not inconceivable that circulation may have been established by
the suffering produced by an overloaded stomach demanding dis-
tribution of its contents. The structure of the Coelenterata offers
the structural conditions of such a process. A want of j^ropul-
sion in a stomach or body sack occupied with its own functions
would lead to a painful clogging of the flow of its products, and
the *' voluntary" contractility of the body or tube-wall being thus
stimulated, would at some point originate the pulsation necessary
to relieve the tension. Thus might have originated the " con-
tractile vesicle" of some protozoa, or contractile tube of some
higher animals ; its ultimate product being the mammalian heart.
So with reproduction. Perhaps an excess of assimilation in well-
fed individuals of the first animals led to the discovery that self-
division constituted a relief from the oppression of too great bulk.
With the increasing specialization of form, this process would be-
come necessarily localized in the body, and growth would repeat
such resulting structure in descent, as readily as any of tlie other
structural peculiarities. No function bears the mark of conscious
origin more than this one, as consciousness is still one of the con-
ditions of its performance. While less completely "voluntary"
than muscular action, it is more dependent on stimulus for its
initial movements, and does not in these display the unconscious
automatism characteristic of the muscular acts of many other
functions.

Bearing in mind the property of protoplasm to organize ma-
chinery which shall work automatically in the absence of con-

396 METAPHYSICAL EVOLUTION.

sciousness, we can glance at the succession of vegetable forms.
The active movements of the primary stages of the x^lgae are well
known. After swimming actively through the water, they settle
down, take root, and assume the role of plants. The Aethalium,
swimming with the movements of a Rhizopod, has been known to
take food before establishing itself on the damp piles of the tan-
bark, where it speedily becomes a low form of fungus. The ap-
proximation of the lower forms of plants to animals is notorious.
The fungi, it is said, are the only terrestrial j)lants which live like
animals on organic matter, appropriating the humus of their rich
nidus in a state of solution. ISTow the paleontology of animals has
absolutely established the fact that the predecessors of all charac-
teristic or sioecialized ty|3es have been unspecialized or generalized
types, '' neither one thing nor another." It may then be regarded
as almost certain that the ancestors of the present higher types
of plants were more animal-like than they ; that the forms dis-
playing automatic movements were more numerous, and the diffi-
culty of deciding on the vegetable or animal nature of a living
organism greater than it is now. Hence it may be concluded that
*^ animal" consciousness has from time to time organized its ma-
chinery and then disappeared forever, leaving as result the per-
manent form of life which we call vegetable. But it is not to be
supposed that all changes of structure cease with the departure of
consciousness. Given spontaneous movement (i. e., growth), and
surrounding conditions, and the resultant product must be struct-
ures adapted to their surroundings, just as the plastic clay is fitted
to its mold. And this is essentially the distinguishing character
of vegetable teleology as compared with animal. In the average
plant we see adaptation to the conditions of unconscious nutrition ;
in the animal, adaptation to conditions of conscious contact with
the world under a great variety of conditions.

IT. GROWTH-FORCE.

The active processes of living beings are examples of conversion
of physical forces, only differing from the conversions observed to
take place in inorganic bodies, in the nature of the machinery
which exhibits them. The construction of this machinerv, as in
its use when finished, involves a conversion of force, the resultant
consisting of the attraction of nutritious material in definite new
directions. This determinate attraction has been regarded as a
distinct force, to which the name of bathmic or growth force has

CONSCIOUSNESS IN EVOLUTION. 397

been ap2)lied. It differs from all the physical forces in this, that
while they are only exerted inversely as the square of the distance,
this one is in addition most excessive where pleasure has been ex-
perienced, and weakest where pain has left its deepest traces. In
other words, its movements express design, the essential condition
of which is consciousness. It is thus evident that it differs utterly
from all other forces, although a retrograde metamorphosis of mat-
ter is as necessary for its production as for that of any of the other
forces. Now, although the evidences that stimulated consciousness,
or if you choose, mind, can modify structure, are, as matter of
observation, not very satisfactory ; yet, since the essential 2:)ecul-
iarity of growth-force is its instant attendance on the needs of
consciousness, it is a permissible hypothesis that its activity is
immediately due to consciousness. This activity is located in
bioplasts which do not exhibit consciousness ; whetlier it co-exists
with consciousness in brain bioplasts is unknown. The successive
exhibitions of this force, from the low^est to the highest of living
beings, have ever been additions to the executive machinery of a
more and more specialized consciousness. Thus it is that its re-
sults in structure have ever become more and more complex, that
is, composed of an ever-increasing number of parts in some region
of the organism. Hence another point of distinction from other
forces exists, which has been pointed out in a previous paper. It
is quite evident that the higher forms of life are the result of con-
tinued superaddition of one result of growth-force on another,
some examples of subtraction or simplification of i^arts being gen-
erally accompanied by a great preponderance of additions. This
is evidence of the accumulation of the property of producing this
kind of force, since each successive addition imposes on the grow-
ing animals a great number of successive stages before the process
reaches its termination, maturity. This involves the belief that
the property of exhibiting frequent *' repetitions" of growth-ac-
tivity exists in a higher degree in the reproductive bioplasm of the
more complex animal than in that of the lower ones. This is in
accordance with the fact of the regular increase in relative com-
plexity and bulk of the nervous system, which accompanies com-
plexity of structure in other respects in the ascending scale of ani-
mals. Thus this force differs from all others, as remarked by Prof.
Hartshorne, in that its expenditure ultimately increases the amount
of its production, because it constructs machinery which feeds its
especial organs more and more successfully. Although expended

398 METAPHYSICAL EVOLUTION.

by becoming energetic, its energy produces the means of its own
increase. Unlike the physical forces whose expenditure renders
matter ever more inert, growth-force when expended adds mate-
rial which, as a profitable addition, increases the power of the cen-
tral machine from which the force emanates, by furnishing an in-
creased supply of food.*

Thus it is evident that growth-force is not concentric nor j)olar
in its activity, as are the physical forces, and that its determina-
tions are antagonistic to these. Its existence in the earth has
been a succession of conquests over polar force, and, if preceding
assumj^tions be true, the gradual progress presented by animals in
abandoning the symmetrical forms exhibited by the lower types
has doubtless been due to the constantly increasing amount of
consciousness.

V. THE DOCTRINE OF THE UXSPECIALIZED.

It is, however, evident that the directing power of conscious-
ness is limited by the nature of the matter with which it has to
deal. There are certain fundamental necessities to which it must
conform. No one supposes that any degree of power can make
twice two equal to six, cause two solid substances to occupy the
same space at the same time, or make an absolutely solid sub-
stance out of incompressible atoms of different forms. These in-
volve the absurdity that something can be made out of nothing,
or nothing out of something. From the present conduct of the
inorganic world, it would appear to possess properties which ren-
der consciousness impossible to it. This is doubtless due to the
relations existing between the atoms or molecules of which its
various species consist. The movements it displays are polar.
The colloid molecular state is, so far as this planet is concerned,
the only one which we know to be capable of consciousness, and
then only while in a state of active transformation. As we have
seen, when protoplasm is once organized and working automati-
cally, consciousness need not be present ; and when this is absent,
the rate of transformation, that is, the amount of food consumed,
is greatly lessened. The excess of expenditure during conscious

* It is incorrect to say that growth-force is "potential" in highly organized-
types, as it is undoubtedly expended in the movement of nutritive pabulum to a
given locality. The maintenance of it in that locality is due to ordinary molecular
cohesion, which can only be set free by greater molecular consolidation.

CONSCIOUSNESS IN EVOLUTION. 399

activity over that necessary to unconscious activity is well known.
It is thus evident that organization renders consciousness unne-
cessary, GO long as external conditions are unchanged, and most
probably a degree of fixity may be attained which renders con-
sciousness impossible. The history of the evolution of animal
types is apparently an illustration of this truth. The relations
of the divisions of the animal kingdom are those of the limbs,
branches, and trunk of a tree. Although the termini of the
branches are successively nearer the root or starting-point as we
proceed from the apex downward or backward, yet the connec-
tion is not from end to end of these. To find this we pass down
the limb to its junction with the trunk, and trace the branches
from the axis outward. Thus with the branches of the animal
kingdom. Although the divisions Vertebrata, Mollusca, Echino-
dermata, etc., stand in an undoubted relation of succession to
each other, there is no connection between the highest representa-
tive of one and the lowest of another. It is the lower or less
specialized forms of each which exhibit the relationship. Thus,
among the articulates, the low group of the worms gives us con-
nection with the Mollusca above by BracMopoda, and the echino-
derms connect themselves with the Vermes by the less specialized
Holothurida. It seems highly probable also that the point of con-
tact of the Vertebrata with these is by one of the lowest divisions,
formerly regarded as molluscan, viz.: the Ascidia. The same
principle holds good within the great divisions. The most spe-
cialized orders of Mammalia are the Artiodactyla, higher Perisso-
dactrjla, the Carnivora, Quadrumana, and perhaps Cetacea ; but
the higher of these have not been derived from the lower. Mod-
ern investigations show that several of them have been derived
from a common type of mammals of the Eocene period, wiiich is
intimately connected with their lower forms, while wanting in
the features which give them their special characters. These two
illustrations serve to explain the universal law of zoological affin-
ity, and therefore of evolution.

The conclusion derived from a survey of this field is, that
structure, like habit, when once established, is closely adhered to,
and that the movement of growth-force once determined or or-
ganized becomes automatic, i. e., independent of consciousness.
Therefore a type which reproduces itself automatically becomes
after a time so established as to be incapable of radical change, in
consequence of a molecular fixity which precludes it. Neverthe-

400 METAPHYSICAL EVOLUTION".

less susceptibility to influences of conscious stimuli may remain in
some j)ortions of the organism, and thus subordinate modifica-
tions of structure have their origin. When conditions of life
change, as they often have done during geologic time, those
changes of structure which are possible take place under the
stimulus of roused consciousness. But if the changes be radical,
affecting the foundation processes of vital economy, the specialized
forms must undoubtedly perish, and the life of the succeeding
time be derived from forms of less pronounced character. The
adaptability of generalized types, as to habits, and the absence of
mechanical peculiarities in their structure, explain fully the cause
of their standing in ancestral relation to all the typical faunse of
the earth.

Nowhere is this truth more remarkably illustrated than in the
case of man, the predominant mammal of the present period.
From the generalized mammalian fauna of the Eocene, the Car-
nivora developed a highly organized apparatus for the destruction
of life and appropriation of living beings as food. The cloven-
footed and odd- toed hoofed orders * are the result of constantly
increasing growth of the mechanical apjDliances for rapid motion
over the ground ; the former superadding exceptional powers of
assimilation of innutritions food. The proboscidians developed
huge bulk and an extraordinary prehensile organ. The Quadru-
mana produced none of these things. In respect to speed of limb
and powers of digestion, both in function and structure, they re-
main nearly in the generalized condition from which the other
orders of mammals have risen. The limbs and teeth of man re-
tain the characters of the primitive type. Yet but two species of
proboscidians remain ; the Perissodactyle multitudes are repre-
sented by but a few vanishing species. The day of the Car-
nivora has passed forever, and the remaining Artiodactyle herds
exist but by the permission of their master, man. But past geo-
logic time reveals no such abundance of true Quadrumana as the
present period displays. These animals were evidently unable to
compete with those of other types in seizing on the opjjortuni-
ties of livino^. Thev were excluded from the chase bv the more
sanguinary ancestors of the Carnivora, and from the field by the
multiplying herds of the swifter or more resistant hoofed animals.
They possessed neither bulk, nor speed, nor cruelty to serve them

* Represented by the ox and the horse.

CONSCIOUSNESS IN EVOLUTION. 40I

in the struggle for existence. So they, were doubtless compelled
to assume an arboreal life, which required little or no modifica-
tion of the limbs for its maintenance, although the ultimate pro-
duction of the grasping thumb from their primitive squirrel-like
feet may be traced to this mode of life. The acquisition of a
hand must be regarded as the first step in that marvelous acces-
sion of experiences which is the condition of mental develoj)ment.
And this latter growth has taken the place of all other means of
conquering a position in the world of life, so that man has even
retrograded in the efficiency of bodily powers. He has lost the
prehensile quality of the hind feet, and the special usefulness of
his canine teeth. But the competition among men continues to
be such as to render it in the highest degree improbable that he
will, as a species, lose the position gained, or suffer any prolonged
diminution of the power of intelligence.

Now it is obvious that the more restricted the conditions of the
life of a given animal type, the more sensitive it will be to changes.
Hence it is that the risks to the existence of Carnivora, Artiodac-
tyla, Prohoscidia, etc., are much greater than to the omnivorous,
all-adaptive order of Quadrwnana. The same is true of mind.
The greater the proportion of unconscious automatism of habits,
the less the power of adaptation ; and this must be the condition
of all animals whose structure is so specialized as to place them
beyond reach of competition, or to cut them off from a wide range
of experiences. The greater the degree of consciousness of stim-
ulus, the greater will be the degree of adaptability to new rela-
tions, and to such constant rousing the unspecialized mind is
always open. If, without strong natural weapons, vigilance is the
price of existence ; if not confined by organization to a peculiar
kind of food, ceaseless investigation is stimulated. And these are
the mental peculiarities which distinguish the monkeys among all
the Mammalia.

The reverse of this picture may now be described, as has been
done by Prof. Vogt. It is well known that the young of many
parasitic animals are free and active, and discover during migra-
tion the localities to which they afterward attach themselves for
life. During the early stages they present the characteristic marks
of their order and class, and in some instances the males, remain-
ing free, continue to do so. Such are the Entoconclia miraMUs,
the SaccidincB and the Trematoda ; the first a mollusk, the second
a cirrhiped crustacean, the third a worm. On their becoming at-

402 METAPHYSICAL EVOLUTION".

tached to their host a successive obliteration of their distinctive
characters takes place, so that they become so simplified as to be
no longer referable to their proper class, but susceptible, as Prof.
Vogt remarks, of being united in a single division. A similar
process is observed in the structural degeneration of the Lernean
parasites, which are at first free, but afterward become parasitic
on fishes. There is in this instance a coincidence between degen-
eracy of structure and loss of compulsory activity : not only is
every function of their sluggish lives automatically performed, but
consciousness itself must experience little stimulus.

From what has preceded, it is evident that automatism is at
once the product and the antagonist of evolution, and that it is
represented in structure by specialization. It appears also that
consciousness is the condition of the inauguration of new habits,
and this is only possible to structures which are not already too
far specialized. This is doubtless true, whether osseous and mus-
cular tissue be concerned in evolution, or whether it be nervous
and brain tissue. Hence in the highest form of development,
that of brain mechanism, automatism is the enemy, and con-
sciousness the condition of progress. As a product of develop-
ment, automatism is the condition of stationary existence, and
constitutes its effective machinery, but every additional step re-
quires the presence of consciousness. This may be expressed in
the every-day language of human affairs, by saying that routine
and progress are the opposite poles of social economy.

YI. THE OKIGIiq" OF COKSCIOUSKESS.

This question has not yet been touched upon, nor is it neces-
sary to give it prolonged attention at present. Consciousness is
in itself inscrutable to us, and the contrast which it presents to
physical and vital forces is the great fact of life. It is obvious
enough that certain molecular conditions are essential to its ap-
pearance ; drugs intensify or obscure it ; concussions and lesions
destroy it. It will doubtless become jDOssible to exhibit a parallel
scale of relations between stimuli on the one hand, and the de-
grees of consciousness on the other. Yet for all this it will be
impossible to express self-knowledge in terms of force. The ques-
tion as to whether the product of the force conversion involved is
the consciousness itself, or only a condition of consciousness, may
receive light from the following consideration.

Nowhere does "the doctrine of the unspecialized" receive

CONSCIOUSNESS IN EVOLUTION. 403

greater warrant than in the constitution of protoplasm. Modern
chemistry refers compound substances to four classes, each of which
is characterized by a special formula of combination. These are
called the hydrochloric-acid type, the water-gas type, the ammonia
type, and the marsh-gas type. These series are defined by the
volumetric relations of their component simple substances : thus, in
the first, a single volume unites with an equal volume of hydrogen ;
in the second, two volumes of hydrogen unite with a single volume of
another element ; in the third, three, and in the fourth, four vol-
umes of hydrogen unite with the single volume of other elements.
Hence the composition of these compounds is expressed by the fol-
lowing formulas — chlorine, oxygen, nitrogen, and carbon being
selected as typical of their respective classes : HCl, HjO, H3N, and
H4O. Now it is an interesting fact that protoplasm is composed
of definite proportions of four simple substances, each one repre-
senting one of the classes above named, or, in other words, the ca-
pacity for proportional molecular combination which characterizes
them. The formula C24N8OH17 expresses the constitution of this
remarkable substance. Now, although the significance of these
combining numbers is unknown, there is a conceivable connection
between the characteristic peculiarities of protoplasm and the na-
ture of the substances which compose it. It is probable that these,
when in combination with each other, exert a mutually antago-
nistic control over each other's especial and powerful tendencies to
form stable, and hence dead, compounds. It is therefore reason-
able that the terms **unspecialized" or *^ undecided" should be
applicable to the molecular condition of protoplasm, and in so far
it is a suitable nidus for higher molecular organization, and a ca-
pacity for higher forms of force-conversion than any other known
substance. If also in inorganic types, as in the organic, the gen-
eralized have preceded the specialized in the order of evolution, we
are directed to a primitive condition of matter which presented
the essentially unspecialized condition of protoplasm, without
some of its physical features. We are not necessarily bound to
the hypothesis that protoplasm is the only substance capable of
supporting consciousness, but to the opposite view, that the proba-
bilities are in favor of other and unspecialized, at present un-
known, forms of matter possessing this capacity.

Consciousness constitutes then the only apparently initial point
of motion with which we are acquainted. If so, we are at liberty
to search for the origin of the physical forces in consciousness, as

404 METAPHYSICAL EYOLUTIOlSr.

well as the vital ; their present unconscious condition being possi-
bly due, as in the case of the vital, to automatism : the automa-
tism being the expression of the atomic type of the substance ex-
hibiting it. And, doubtless, the simple quantitative relations of
the lowest types of forces are related to correspondingly simple
geometrical conditions of matter, both representing the simplest
grade of automatic action and machinery. We may also suppose
that all of these primary conditions were necessary to the produc-
tion of protoplasm, the only form of matter known to us in which
consciousness can persist.

In conclusion, it is obvious that the metastatic condition of
protoplasm necessary to the persistence of consciousness could not
be supported without a constant source of supply by assimilation.
Hence it would appear that the preliminary creation of dead and
unconscious substances and organisms were a necessary antecedent
to the accomplishment of this end ; at least under circumstances
of temperature under which living beings or protoplasm exist on
this planet. Without the unconscious inorganic and organic prod-
ucts of nature, consciousness could not exist on the earth for a
day. No animal can maintain consciousness without food ; and
that food must be, in the main, protoplasm. Protoplasm is manu-
factured from inorganic matter by the (sujoposed) unconscious
protoplasm of the plant. What form of matter originally gave
origin to protoplasm is yet unknown, but it is obvious that the
ordinary physical forces must have existed as conditions of its
creation, since now they are absolutely necessary to its persistence.
Hence we may view the succession of automatic activities some-
what in the light of the fagots used by the elephant to lift itself
from the well into which it had fallen. One placed upon another
finally raised the footing to an elevation which enabled the animal
to obtain its freedom.

Consciousness is the essential condition of personality ; so that
in this view of the case we are led to a j)rimitive personality, al-
though not to what we call life. And the reason why this person-
ality is to us so obscure a conception is probably to be found in
the fact that it, as well as ourselves, is conditioned in its rela-
tions to matter by necessary laws of ^'^mathematical" truth.

XIX.
ON ARCHJESTHETISM.

I. THE HYPOTHESIS OF USE AND EFFORT.

The claims of the theory of Lamarck, that use modifies struct-
ure in the animal kingdom, are being more carefully considered
than heretofore, and are being admitted in quarters where they
have been hitherto neglected or ignored. Eleven years ago I re-
stated the question as follows : *

** The influences and forces which have operated to j^roduce
the type-structures of the animal kingdom have been plainlv of
two kinds : 1. Originative; 2. Directive. The prime importance
of the former is obvious ; that the latter is only secondary in the
order of time or succession, is evident from the fact that it con-
trols the preservation or destruction of the results or creations of
the first.

*^ Wallace and Darwin have propounded as the cause of modi-
fication in descent their law of natural selection. This law has
been epitomized by Spencer as the ^survival of the fittest.' Tiiis
neat expression no doubt covers the case, but it leaves the origin
of the fittest entirely untouched, Darwin assumes a tendency
to variation ' in nature, and it is plainly necessary to do this, in
order that materials for the exercise of a selection should exist.
Darwin and Wallace's law Is, then, only restrictive, directive, con-
servative, or destructive of something already created. I propose
then to seek for the originative laws by which these subjects are
furnished — in other words, for the causes of the origin of the
fittest.

" It has seemed to the author so clear from the first as to re-
quire no demonstration, that natural selection includes no actively
progressive principle whatever ; that it must first wait for the de-

* "The Method of Creation," 1871, pp. 2 and 18, Walker Prize Essay, Proceeds.
Amer. Phllos. Soc, pp. 230-246.

406 METAPHYSICAL EVOLUTION.

velopment of variation, and then, after securing the survival of
the best, wait again for the best to i^roject its own variations for
selection. In the question as to whether the latter are any better
or worse than the characters of the parent, natural selection in no
wise concerns itself."

In seeking for the causes of the origin of variation, the follow-
ing hypothesis was proposed :

^^ What are the influences locating growth -force ? The only
efficient ones with which we are acquainted are, first, physical
and chemical causes ; second, use ; and I would add a third, viz. :
effort. I leave the first as not especially prominent in the econ-
omy of type-growth among animals, and confine myself to the
two following. The effects of use are well known. We can not
use a muscle without increasing its bulk ; we can not long use
the teeth in mastication without inducing a renewed deposit of
dentine within the pulp-cavity to meet the encroachments of at-
trition. The hands of a race of laborers are always larger than
those of men of other pursuits. Pathology furnishes us with a
host of hypertrophies, exostoses, etc., produced by excessive use,
or necessity for increased means of performing excessive work.
The tendency, then, induced by use in the parent, is to add
segments or cells to the organ used. Use thus determines the
locality of new repetitions of parts already existing, and deter-
mines an increase of growth-force at the same time, by the in-
crease of food always accompanying increase of work done, in
every animal.

^ ^ But supposing there be no part or organ to use. Such must
have been the condition of every animal prior to the appearance
of an additional digit or limb or other useful element. It appears
to me that the cause of the determination of growth-force is not
merely the irritation of the part or organ used by contact with
the objects of its use. This would seem to be the remote cause
of the deposit of dentine in the used tooth ; in the thickening
epidermis of the hand of the laborer ; in the wandering of the
lymph-cells to the scarified cornea of the frog in Cohnheim's ex-
periment. You can not rub the sclerotica of the eye without
producing an expansion of the capillary arteries and correspond-
ing increase in the amount of nutritive fluid. But the case may
be different in the muscles and other organs (as the pigment cells
of reptiles and fishes) which are under the control of the volition
of the animal. Here, and in many other instances which might

ON" ARCHiESTHETISM. 407

be cited, it can not be asserted that the nutrition of use is not
under the direct control of the will through the mediation of
nerve-force. Therefore I am disposed to believe that growth-
force may be, through the motive force of the animal, as readily
determined to a locality where an executive organ does not exist,
as to the first segment or cell of such an organ already com-
menced, and that therefore effort is, in the order of time, the
first factor in acceleration."

A difficulty in the way of this hypothesis is the frequently
unyielding character of the structures of adult animals, and the
difficulty of bringing sufficient pressure to bear on them without
destroying life. But in fact the modifications must, in most in-
stances, take place during the period of growth. It is well
known that the mental characteristics of the father are trans-
mitted through the spermatozooid, and that therefore the molec-
ular movements which produce the mechanism of such mental
characters must exist in the spermatozooid. But the material of
the spermatozooid is combined with that of the ovum, and the
embryo is composed of the united contents of both bodies. In a
wonderful way the embryo develops into a being which resembles
one or both parents in minute details. This result is evidently
determined by the molecular and dynamic character of the origi-
nal reproductive cells, which necessarily communicate their prop-
erties to the embryo, which is produced by their subdivision.
Rud. Hering has identified this property of the original cells with
the faculty of memory. This is a brilliant thought, and, under
restriction, probably correct. The sensations of persons who have
suffered amputation shows that their sensorium retains a picture
or map of the body so far as regards the location of all its sensitive
regions. This simulacrum is invaded by consciousness whenever
the proper stimulus is applied, and the locality of the stimulus is
fixed by it. This picture probably resides in many of the cells,
both sensory and motor, and it doubtless does so in the few cells
of simple and low forms of life. The spermatozooid is such a
cell, and, how or why we know not, also contains such an ar-
rangement of its contents, and contains and communicates such
a type of force. It is probable that in the brain-cell this is the
condition of memory of locality. If now an intense and long-
continued pressure of stimulus produces an unconscious picture
of some organ of the body in the mind, there is reason to suppose
that the energies communicated to the embryo by the spermato-

408 METAPHYSICAL EVOLUTION'.

zooid and ovum will partake of tlie character of the memory thus
created. The only reason why the oft-repeated stories of birth-
marks are so often untrue is because the effect of temporary im-
pressions on the mother is not strong enough to counterbalance
the molecular structure established by impressions oftener re-
peated throughout much longer periods of time.

The demonstration of the truth or falsity of this position, so as
to constitute it the true doctrine of evolution, could only be veri-
fied from the prosecution of the science of paleontology. It is
only in this field that the consecutive series of structures can be
obtained which show the directions in which modification has
taken place, and thus furnish evidence as to the causes of change.
The most complete result of these investigations, up to the present
time, has been the obtaining of sufficiently full series of the Mam-
malia of the Tertiary period to show their lines of descent. In
this way the series of modifications of their teeth and feet has
been discovered, and the homologies of their parts been ascer-
tained.* Perhaps the most important result of these investiga-
tions is the following : The variations from which natural selec-
tion has derived the persistent types of life have not been general
or even very extensive. They have been in a limited number of
directions, f and the most of these have been toward the increase
in perfection of some machine. They bear the impress of the
presence of an adequate originating cause, directed to a special
end. Some of the lines struck out have been apparently inade-
quate to cope with their environment, and have been discon-
tinued. Others have been more successful, and have remained,
and attained further modification.

The reader can estimate the chance of the production of an
especially adaptive mechanism in the absence of any pressure of
force directing growth to that end. It appears to me that the
probability of such variation appearing under such circumstances
is very slight indeed, and its continuance through many geologic
ages directed to the perfecting of one and the same machine still
smaller. For this reason, attempts have been made to demon-
strate a mechanical cause for the modifications of structure ob-

* " Homologies and Origin of the Molar Teeth of the Mammalia educabilia."
Journal Academy Nat. Sciences, Philadelphia, March, 1874. Proceedings Academy
Nat. Sci., 1865, p. 22.

f See Hyatt on this point, *' Tertiary Planorbis of Steinheim." Anniv. Mem.
Bost. Soc. Nat. Hist., 1880, p. 20.

ON APwCn^STHETISM. 409

served. For these I refer to papers by Messrs. Alpheus Hyatt,
J. A. Ryder and myself : by Prof. Hyatt ..." Upon the Effects
of Gravity on the Forms of Shells and Animals ; " * Mr. Ryder
*'0n the Mechanical Genesis of Tooth Forms ;" f and '*0n the
Laws of Digital Reduction ;" ]; by myself '' On the Origin of the
Specialized Teeth of the Oarnivora ; " * " On the Origin of the
Foot Structures of the Ungulates ; " || "On the Effect of Impacts
and Strains on the Feet of Mammalia." ^ Now demonstration of
the meclianical effects of the application of force to matter can
only be obtained by observation of the process, and this can not
be seen, of course, by the observation of fossils. The relation of
the observed facts to the hypothesis is, however, shown by the
above papers to be so precise that it only needs observation on the
production of similar changes by similar causes in living types to
give us a demonstration by induction, which will satisfy most
minds. That such facts have been observed among the lower ani-
mals is well known. The change of form of animals without
hard parts, in adaptation to their environment, is an every-day
occurrence.

That these views are now shared by many naturalists is be-
coming every day more evident. Prof. E. Dubois-Raymond ^ has
recently delivered a lecture before the physicians of the German
army, on exercise or use, in which he makes some important
admissions. We give the following extract : " We should be,
therefore, free to admit, with some appearance of reason, that the
vigor of the muscles of wings and of digging feet ; the thick
epidermis of the palm of the hand and of the sole of the foot ;
the callosities of the tail and of the ischia of some monkeys ; the
processes of bones for the insertion of muscles ; are the conse-
quences of nutritive and formative excitation, transmitted by
heredity." In this position Prof. Raymond is in strict accord
with the Lamarckian school of evolutionists. But Prof. Raymond
still clings to the obscurities of the Darwinians, though Darwin
himself is not responsible for them, in the following sentences :
" It is necessary to admit, along with development by use, develop-

* "Proceeds. Amer. Assoc. Adv. Science," 1880, p. 527.

f " Proceedings Academy Philadelphia," 1878, p. 45 ; 1879, 47.
X Loe. cit.^ 1877, October.

# " American Naturalist," March, 1879, p. 171.

II Loc. cit, April, 1881, p. 269. ^ Loc. cit, July, 1881, p. 542.

l "Revue Scientifique," Paris, Jan. 28, 1882.

410 METAPHYSICAL EYOLUTION.

ment by natural selection, and that for three reasons. First,
there are innumerable adaptations — I cite only those known as
mimetic coloration — which appear to be only explicable by nat-
ural selection and not by use. Second, plants which are, in their
way, as well adapted to their environment as animals, are of
course incapable of activity. Thirdly, we need the doctrine of
natural selection to explain the origin of the capacity for exercise
itself. Unless we admit that which it is imj^ossible to do from a
scientific stand-point, that designed structures have a mechanical
origin, it is necessary to conclude that in the struggle for exist-
ence the victory has been secured by those living beings who in
exercising their natural functions have increased by chance {^ par
hasard^) their capacity for these functions more than others, and
that the beings thus favored have transmitted their fortunate gifts
to be still further developed by their descendants."

To take up first the second and third of these propositions.
Prof. Kaymond does not for the moment remember that move-
ment (or use) is an attribute of all life in its simplest forms, and
that the sessile types of life, both vegetable and animal, must, in
view of the facts, be regarded as a condition of degeneration. It
is scarcely to be doubted that the primordial types of vegetation
were all free swimmers, and that their habit of building cellulose
and starch is resjjonsible for their early-assumed stationary condi-
tion. Their protoplasm is still in motion in the limited confines
of their walls of cellulose. The movements of primitive plants
have doubtless modified their structure to the extent of their dura-
tion and scope, and probably laid slightly varied foundations, on
which automatic nutrition has built widely diverse results. We
may attribute the origi7i of the forms of the vegetable kingdom
to three kinds of motion which have acted in conjunction with
the physical environment ; first, their primordial free movements ;
second, the intracellular movements of protoplasm ; third, the
movements of insects, which have doubtless modified the structure
of the floral organs. Of the forms thus produced, the fit have sur-
vived and the unfit have been lost, and that is what natural selec-
tion has had to do with it.

The origin of mimetic coloration, like many other things, is yet
unknown. An orthodox Darwinian attributes it to ^' natural selec-
tion," which turns out, on analysis, to be '"liasard.'^^ The survival
of useful coloration is no doubt the result of natural selection.
But this can not be confounded with the question of origin. On

ON AROH^STHETISM. 411

this point the Darwinian is on the same footing as the old-time
Creationist. The latter says God made the variations, and the
Darwinian says that they came by chance. Between these posi-
tions science can perceive nothing to choose.

I have attempted to explain the relation which non-adaptive
structures bear to the theory of use and effort, in the following
language : *

*' The complementary diminution of growth-nutrition follows
the excess of the same in a new locality or organ, of necessity, if
the whole amount of which an animal is capable be, as I believe
[for the time being], fixed. In this way are explained the cases
of retardation of character seen in most higher types. The dis-
covery of truly complementary parts is a matter of nice observation
and experiment. Perhaps the following cases may be correctly ex-
plained.

'^ A complementary loss of growth-force may be seen in the ab-
sence of superior incisor teeth and digits in ruminating Mammalia,
where excessive force is evidently expended in the development of
horns, and complication of stomach and digestive organs. The
excess devoted to the latter region may account for the lack of
teeth at its anterior orifice, the mouth ; otherwise, there appears
to be no reason why the ruminating animals should not have the
superior incisors as well developed as in the odd-toed (Perisso-
dactyl) Ungulates, many of which graze and browse. The loss to
the osseous system in the subtraction of digits may be made up in
the development of horns and horn-cores, the horn sheath being
perhaps the complement of the lost hoofs. It is not proposed to
assert that similar parts or organs are necessarily and in all groups
complementary to each other. The horse has the bones of the
feet still further reduced than the ox, and is nevertheless without
horns. The expenditure of the complementary growth-force may
be sought elsewhere in this animal. The lateral digits of the
EquidcB are successively retarded in their growth, their redaction
being marked in Hippotlierium, the last of the three-toed horses ;
it is accompanied by an almost coincident acceleration in the
growth-nutrition of the middle toe, which thus appears to be com-
plementary to them."

* "Method of Creation," p. 23, ISTl.

412 METAPHYSICAL EYOLUTIOI^.

II. THE OFFICE OF COKSCIOUSi^ESS.

If the law of modification of structure by use and effort be
true, it is evident that consciousness or sensibility must play an
important part in evolution. This is because movements of ani-
mals are plainly in part controlled by their conscious states. The
question as to how many of the actions of animals are due to con-
scious states at once arises. It is well known that most of the
more strictly vital functions are unconsciously performed. Not
only these, but many acts which have to be learned come to be
performed in unconsciousness. Further, movements appropriate
to needs which arise at the moment, and which are ordinarily
termed voluntary, because they require the introduction of more
or less of the rational faculty, are readily performed by verte-
brated animals deprived of a brain, through the agency of the
spinal cord alone.* The history of the origin of these movements
must then be traced.

The movements of living beings generally possess the pecul-
iarity of design, in which they differ from the movements of non-
living bodies. That is, their actions have some definite reference
to their well-being or pleasure, or their preservation from injury
or pain, and are varied with circumstances as they arise. This is
not the case with non-living bodies, which move regardless of
their integrity or of that of objects near them. This characteris-
tic at once suggests that some element enters into them which is
wanting to the movements of non-living masses. It has been
suggested that the attraction of animals for their food and their
repulsion from pain are derivatives from the attractions and repul-
sions of inorganic bodies, supposed to be the exhibitions of the
force called chemism. But this supposition does not explain the
wide difference between the two classes of acts. The adaptation
to the environment seen in organic acts is unknown to the inor-
ganic world, while the invariable character of the motions of in-
organic force is greatly modified in beings possessed of life.
Whether consciously performed or not, the acts of organic beings
resemble those of conscious beings actuated by instincts of hunger,
reproduction, and defense.

An explanation of these facts seems to be offered by a well-

* Such expressions as " unconscious sensibility " and " unconscious will " are not
used here, as being self -contradictory in terms and without meaning.

ON" ARCH^STHETISM. 413

known phenomenon. We know that it is true of ourselves and
of many other animals, that while all new movements have to be
learned by repeated attempts, with each succeeding movement
the act becomes easier, and that finally it can be performed with-
out requiring any attention whatever. If continued, the move-
ment becomes automatic, so that it may be or is performed in a
state of unconsciousness. In the words of Spencer, nervous cur-
rents move most readily along accustomed channels. Thus the
" habits " of animals may be looked on as movements acquired
in consciousness, and become automatic through frequent repeti-
tion. Not only this, but the organization thus produced in the
parent is transmitted to the succeeding generation, so that the
movements of the latter are automatically and often unconsciously
performed. This view may be even extended to the purely vital
functions, with every probability of its being the true explanation
of their origin and development. On a former occasion * I wrote :
*^In accordance with this view, the automatic 'involuntary'
movements of the heart, intestines, reproductive systems, etc.,
were organized in successive states of consciousness, which con-
ferred rhythmic movements whose results varied with the ma-
chinery already existing and the material at hand for use. It is
not inconceivable that circulation may have been established by
the suffering produced by an overloaded stomach demanding dis-
tribution of its contents. The structure of the Coelenterata offers
the structural conditions of such a process. A want of propulsive
power in a stomach or body sac occupied with its own functions,
would lead to a painful clogging of the flow of its i3roducts, and
the * voluntary ' contractility of the body or tube wall being thus
stimulated, would at some point originate the pulsation necessary
to relieve the tension, Thus might have originated the ' con-
tractile vesicle ' of some protozoa, or contractile tube of some
higher animals ; its ultimate product being the mammalian heart.
So with reproduction. Perhaps an excess of assimilation in wtII-
fed individuals of the first animals led to the discoverv that self-
division constituted a relief from the oppression of too great
bulk. With the increasing specialization of form, this process
would become necessarily localized in the body, and growth would
repeat such resulting structure in descent as readily as any of
the other structural peculiarities. No function bears the mark

* " Consciousness iu Evolution." "Penn Monthly," August, 1875, p. 565.

414 METAPHYSICAL EYOLUTION".

of conscious origin more than this one, as consciousness is still
one of the conditions of its performance. While less completely
* voluntary ' than muscular action, it is more dependent on stim-
ulus for its initial movements, and does not in these display the
unconscious automatism characteristic of the muscular acts of
many other functions."

It was not proposed in the preceding paragraph that the con-
tractility of living protoplasm should be regarded as due to con-
sciousness, but that the location in a particular place of a contrac-
tility already existing might be due to that cause.

The preceding hypotheses bring us to a general theory of the
evolution of organic structures or species. It is that they are the
result of movements long continued and inherited, and that the
character of these movements was originally determined by con-
sciousness or sensibility. It remains then to consider the nature
of consciousness.

It may be mentioned that it is here left open whether there be
any form of force which may be especially designated as *^ vital."
Many of the animal functions are known to be physical and
chemical, and if there be any one which appears to be less expli-
cable by reference to these forces than the others, it is that of
nutrition. Probably in this instance force has been so metamor-
phosed, through the influence of the originative or conscious force
in evolution, that it is a distinct species in the category of forces.
Assuming it to be such, I have given it the name of Bathmism
('^Method of Creation," 1871, p. 26). Perhaps the contractility
generally regarded as an attribute of living protoplasm may be a
mechanical phenomenon dependent of course on nutrition ; or it
may be the exhibition of a force peculiar to living beings ; and
hence one of the * vital ' group.

III. ARCH^STHETISM.

The doctrine of evolution derives the organs of special sense
from those of simple sensibility or touch. In other words, their
history has been that of other organs ; the complex have been
derived from the general and simple. There are then generalized
consciousness and specialized consciousness. A number of forms
of consciousness multiplies its vividness, the one kind reenforcing
the other by a slightly different appreciation of the same thing.
In the case of persons deprived of the sense of touch, the sense
of sight is not sufficient to convince them of their own existence,

ON ARCHiESTHETISM. 415

as a matter of intellectual reflection. When there is no nervous
system we must suppose sensibility to be generally distributed
throughout the protoplasmic substance of the animal. The locali-
zation of consciousness must depend on a localization of the kind
and condition of protoplasm which sustains it ; while in other
parts of the body the protoplasm is modified in other directions
and for other purposes. If this be true, the nervous tissue of the
higher animals should retain the characters of the lowest simple
organisms. In point of fact this is the case, the nucleated cell
being the essentially active element in the functions of brain and
nerve, and being more numerous in that tissue than in any other.

The remarkable evanescence of consciousness is one of its most
marked characteristics. It is this peculiarity which has led
many thinkers to deny its existence in the lower animals, and to
induce others to believe that it can have had but little place among
the causes of evolution. Partly for the same reason many biolo-
gists attempt to derive it by metamorphosis from some form of
force.

But the nature of consciousness is such that it can not be de-
rived from unconsciousness, any more than matter can be derived
from no matter, or force from no force. The *' unthinkable dogma
of creation " (Haeckel) can not be applied to consciousness more
than to matter or force. It is a thing by itself, and with matter
and force forms a trio of primitive things which have to be
accepted as ultimate facts. This is perfectly consistent with the
position that consciousness is an attribute of matter, and neither
more nor less difficult to comprehend than the fact that force is
an attribute of matter. This view is maintained in a fashion of
his own by G. H. Lewes. Prof. Raymond* says in support of
the same position :

*^ More temperate heads betrayed the weakness of their dia-
lectics in that they could not grasp the difference between the
view which I opposed, that consciousness can be explained upon a
mechanical basis, and the view which I did not question, but sup-
ported with new arguments, that consciousness is bound to mate-
rial antecedents." This position has been maintained by various
writers, among them Prof. Allman f and the writer. But Prof.

* Address on the celebration of the Birthday of Leibnitz. " Pop. Science Month-
ly," Feb., 1882.

f Address delivered before the British Association for the Advancement of
Science.

416 METAPHYSICAL EYOLUTIOK

Raymond has not found it to be acceptable to his nearest contem-
poraries. He says : " The opposition which has been offered to
my assertion of tiie incomprehensibility of consciousness on a me-
chanical theory, shows how mistaken is the idea of the later phi-
losophy, that that incomprehensibility is self-evident. It ap-
pears, rather, that all philosophizing upon the mind must begin
with the statement of this point." In stating this point some
years ago we used the following language :* ^^It will doubtless
become possible to exhibit a parallel scale of relations between
stimuli on the one hand and the degrees of consciousness on the
other. Yet for all this it will be impossible to express self-knowl-
edge in terms of force." And again : f *'An unprejudiced scru-
tiny of the nature of consciousness, no matter how limited that
scrutiny necessarily is, shows that it is qualitatively comparable
to nothing else. . . . From this stand-point it is looked upon as
a state of matter which is coeternal with it, but not coextensive."

It is probable then that consciousness is a condition of matter
in some peculiar state, and that wherever that condition of mat-
ter exists consciousness will be found, and that the absence of that
state implies the absence of consciousness. What is that state ?

It would be a monstrous assumption to suppose that conscious-
ness and life are confined to the planet on which we dwell. I
presume that no one would be willing to maintain such an hypoth-
esis. Yet it is obvious that if there be beings possessed of these
attributes in the planets Mercury and Saturn, they can not be
composed of protoplasm, nor of any identical substance in the
two. In the one planet protoplasm would be utterly disorganized
and represented by its component gases ; in the other it would be
a solid, suitable for the manufacture of sharp-edged tools. J; But
as it is probable that j^rotoplasm is adapted for the phenomena of
consciousness by a certain peculiarity of its constitution, it seems
evident that other substances having a similar peculiarity may
also be able to sustain it. I have elsewhere attempted to discover
what this is, in the following language : *

*^ Nowhere does ^the doctrine of the unspecialized ' receive
greater warrant than in the constitution of protoplasm. Modern
chemistry refers compound substances to four classes, each of

* "Consciousness in Evolution." "Penn Monthly," July, 1875.
f " The OrijTin of the Will." " Penn Monthly," 1877, p, 439.
X Frazer in "American Naturalist," 1879, p. 420.

* "Consciousness in Evolution," 1S75, p. 573.

ON AECH^STHETISM. 4I7

which is characterized by a special formula of combination.
These are called the hydrochloric-acid type, the water-gas type,
the ammonia type, and the marsh-gas type. These series are de-
fined by the volumetric relations of their component simple sub-
stances : thus in the first, a single volume unites with an equal
volume of hydrogen ; in the second, two volumes of hydrogen
unite with a single volume of another element ; in the third, three,
and in the fourth, four volumes of hydrogen unite with the single
volume of other elements. Hence the composition of these com-
pounds is expressed by the following formulas — chlorine, oxygen,
nitrogen, and carbon being selected as typical of their respective
classes : HCl, H2O, H3N", and H4C. Noav it is an interesting fact
that protoplasm is composed of definite proportions of four simple
substances, each one representing one of the classes above named,
or, in other words, the capacity for proportional molecular com-
bination which characterizes them. The formula C24N8OH1T ex-
presses the constitution of this remarkable substance. Now, al-
though the significance of these combining numbers is unknown,
there is a conceivable connection between the characteristic pecul-
iarities of protoplasm and the nature of the substances which
compose it. It is probable that these, when in combination with
each other, exert a mutually antagonistic control over each other's
especial and powerful tendencies to form stable, and hence dead,
compounds. It is therefore reasonable that the terms ' unspecial-
ized' or -^undecided' should be applicable to the molecular con-
dition of protoplasm, and in so far it is a suitable nidus for higher
molecular organization, and a capacity for higher forms of force-
conversion than any other known substance. If also in inorganic
types, as in the organic, the generalized have preceded the spe-
cialized in the order of evolution, we are directed to a primitive
condition of matter which presented the essentially un specialized
condition of protoplasm, without some of its physical features.
We are not necessarily bound to the hypothesis that protoplasm is
the only substance capable of supporting consciousness, but to the
opposite view, that the probabilities are in favor of other and un-
specialized, but unknown, forms of matter possessing this ca-
pacity."

The condition of living protoplasm was also referred to in the
following language in a later publication : *

* " The Origin of the Will." " Pouii Monthly," June, 1877, p. 439.

418 METAPHYSICAL EVOLUTION.

^^ The cause of tlie difference between conscious and uncon-
scious force must be secondarily due to different conditions of
matter as to its atomic constitution ; consciousness being only
possible, so far as we can ascertain, to matter which has not fallen
into fixed and automatic relations of its atoms."

Protoplasm in the form of food is not conscious ; and tissue
formed of protoplasm is not conscious, excepting certain cells
where the forming process is in action. Nor is consciousness
present in all cells where nutrition is active. From the increased
consumption of energy, and the increased expenditure of energy
(heat, Lombard) which takes place during conscious processes, we
may well believe that the decomposition of protoj^lasm is more
considerable in such processes than in other forms of nervous ac-
tivity. We can imagine simple nutrition to be a condition of the
elements of this substance in which the chemical force is simul-
taneously combining and dissolving its combination, and that dur-
ing the process there is a condition in which the chemism is for
the time being unsatisfied, though present. The direction which
this nutrition or metastasis takes, is due to the arrangement of the
molecules already existing in the tissue, the new molecules taking
the form of the old ones in replacement, so long as no extraneous
force interferes. That they are rearranged under the influence of
consciousness is apparent in the origin of variations of structure
in accordance with the views of evolution already entertained. It
is the arrangement of the molecules which constitutes the auto-
matic machinery of nutrition as well as of other activities, so that
consciousness necessarily only appears in that stage of nutrition
while the matter is in a transition state, and unformed. Whether
chemism must be regarded as suspended, or only unsatisfied, at
this stage, can only be imagined. As non-satisfaction is probably
the tem|)orary condition in all nutrition, it is not unlikely that sus-
pension may be the condition of consciousness.

Perhaps the character of the components of protoplasm is such
that the movements of their atoms, i. e., their chemism, mutually
interfere and destroy each other, as in the cases of the interference
of the waves of light and sound.

The colloid form of protoplasm is especially favorable to inter-
nal movements which shall not destroy the integrity of the mass,
perhaps more so than a gaseous state in a compound of similar con-
stitution. It is, moreover, more favorable to the preservation of
molarity than a gas could be, on account of the ease with which

ON ARCIIiESTnETISM. 4I9

it adheres to solid substances, and transports and locates them as
part of its external and internal supports. But it is not incon-
ceivable that under other conditions of temperature, etc., the
gaseous condition of matter jnight answer the same purpose. It
must be borne in mind, however, that this is a subordinate ques-
tion, and that the real characteristic of the "physical basis of life "
is to be found rather in its generalized dynamic condition.

We must then believe that wherever this generalized condition
exists, consciousness will be present. As soon as mechanical or
chemical force appears in the molecules of the sustaining sub-
stance, consciousness disappears. The organism has taken the first
step toward death, but is not dead, but is anmsthetized. Constant
nutrition is essential to the performance of all life functions, in-
cluding consciousness, and it is evident that this is necessary to
the maintenance of the unspecialized condition in which the latter
appears.

Is the appearance of sensibility on the development of its sus-
taining condition, evidence that the latter stands to the former in
the relation of cause and effect ? If the view of the pre-existence
of consciousness be true, there is no more relation of cause and
effect than in the case of the opening of a door which admits a
wind. The force expended in opening the door is not converted
into the energy exerted by the wind as it enters the room. It
simply releases it, or admits it to a new field. It is, however, true,
that consciousness having once entered, a larger conversion of force
is necessary to its ^persistence than is expended during its absence.
Like combustion, which is only communicable under suitable con-
ditions, consciousness having once been transmitted to a new cestJie-
topliore* lives on it, and requires constant supplies of material for
its sustenance.

The hypothesis of the primitive and creative function of con-
sciousness may be called Archmsthetism,

IV. PAN^STHETISM.

It has been the custom of men from the dawn of thought to
attempt to construct for themselves cosmogonies and theologies.
Science is yet far from supplying the facts necessary to the con-
struction of a true system of the universe, and philosophy can only
stretch out a little further into the unknown by the use of neces-

* -^sthetophore, a substance which sustains consciousness.

420 METAPHYSICAL EVOLUTIOIN'.

sary inference. In spite, however, of the insufficiency of the data,
men still suggest new yiews or cling to old ones, and an occasional
flight into this region of thought at least brings the thinker into
sympathy with the thoughts of his fellow-men.

The admission of the possibility of the existence of conscious-
ness in other forms of matter than protoplasm, and in other regions
than the Earth, lends countenance to a rational belief in the so-
called ^^supernatural" (better called the supersensuous) so preva-
lent among men in irrational forms. The question naturally
arises. Is there any generalized form, of matter distributed through
the universe which could sustain consciousness ? The presump-
tion is that such a form of matter may well exist. Evolution or
specialization has only worked up part of its raw material in the or-
ganic world. Wherever primitive conditions remain, there primi-
tive organisms abound. Protozoa are yet numerous on land, and
the Protolatliyhius inhabits the depths of the sea. Highly spe-
cialized forms of life are in fact numerically a minority of living
beings. May not this be true also of inorganic beings ? It is
thought that various celestial bodies reiDresent unfinished worlds.
Is it not probable that the grand sources of matter not yet spe-
cialized into the sixty odd substances known to us, may still sus-
tain the primitive force not yet modified into its species, and that
this combination of states may be the condition of persistent con-
sciousness from which all lesser lights derive their brilliancy ?
There is much to warrant such a view in the observed facts of life,
taken in connection with the general course of evolution. More-
over, that some form of matter connects the interstellar S2oaces, is
thought to be proved by the transmission of light in some cases,
and light and heat in others. That such a form of matter per-
vades all spaces whatever, is the theory of some physicists. If it
be so generalized as to be capable of sustaining consciousness, it
becomes the source from which other substances derive it, so soon
as they, through the energy of nutrition, which resists death,
maintain the same primitive and unformed constitution capable
of exhibiting it.

Of course there is no evidence in our own memory of the ex-
istence of our personality prior to our human experience. No
one on awaking from unconsciousness remembers having been
anywhere in particular during the interval. These facts may be
harmonized with the theory here presented, on the supposition
that memory is lost on a transfer of consciousness from one physi-

ON ARCH^STHETISM. 421

cal basis to another. The arguments in favor of a transfer of
consciousness do not sustain the idea of a transfer of memory.
Memory requires an arrangement of molecules or atoms which
when finished no longer exhibits consciousness. With proper
stimulus, when the proper kind of force conversion is set up in
them, consciousness extends into them, and, taking their form,
produces reminiscence or conscious memory. The molecular
arrangement would be probably lost on a transfer of conscious-
ness to a new material basis. It might then be supposed that with
every such transfer a new personality is established. Though
the correct definition of personality includes memory as well as
consciousness, when viewed as an objective concept, it may be
questioned whether memory is necessary to the subjective belief
in one's own personality. Those insane persons who believe that
they have lost their personality, and think that they are some one
else, nevertheless recognize the fact that what they now are has
a continuity of existence with what they once were. The mate-
rial limitations of consciousness are the authors of the kind of
personality it presents. A limitation or an expansion of its range
would not destroy the idea of personality, but would simply re-
strict or extend it. The possible confluence of many personalities
would not destroy them, but each one would regard the others
as additions to himself, and himself, therefore, as so much the
greater being.

As a summary of the preceding conclusions, the following
analysis of metaphysical systems may be given. It defines the
place of the doctrine of archsesthetism, above proposed, as dis-
tinguished from the opposing view of metsesthetism, which is
held by many monists :

I. Consciousness (" spirit ") is independent of mattei' Dualism.

II. Consciousness is an attribute of matter Monism.

o. Consciousness is primitive and a cause of evolution ArcJucsthetism.

iS. Consciousness is a product of the evolution of matter and force.

Metcesthdism.

XX.

ON CATAGENESIS.*

I. THE EVOLUTIOJ^ OF ORGANISMS.

The general proposition that life has preceded organization in
the order of time, may be regarded as established. It follows ne-
cessarily from the fact which has been derived from paleontological
investigation, that the simple forms have, with few sporadic ex-
ceptions, preceded the complex in the order of appearance on the
earth. The history of the lowest and simplest animals will never
be known, on account of their perishability ; but it is a safe infer-
ence from what is known, that the earliest forms of life were the
rhizopods, whose organization is not even cellular, and includes
no organs whatever. Yet these creatures are alive, and authors
familiar with them agree that they display, among their vital
qualities, evidences of some degree of sensibility.

The following propositions were laid down by Lamarck, as
established by facts known to him, in 1809 : f

I. '^In every animal which has not passed the term of its de-
velopment, the frequent and sustained employment of an organ,
gradually strengthening it, develops and enlarges it, and gives it
power proportional to the duration of its use ; whilst the constant
disuse of a like organ insensibly weakens it, deteriorates it, pro-
gressively reduces its functions, and finally causes it to disappear.

II. *^ All that nature acquires or loses in individuals, through
the influence of circumstances to which the race has been exposed
for a long time, either by the predominant use of an organ or by
the disuse of such part, she preserves by generation among new

* An address delivered before the Biological Section of the American Associa-
tion for the Advancement of Science, at Philadelphia, September 4, 1884, by E. D.
Cope, vice-president.

f "Philosophic Zoologique," Pt. I, p. 235 (Edit. 1830).

ON CATAGENESIS. 423

indiyiduals wliicli spring from it, j^rovidod the acquired changes
be common to both sexes or to those which produce new indi-
yiduals.''

The same ^proposition was previously enunciated by Lamarck
in the following condensed form ('^Recherches sur les Corps
vivans," p. 50) :

^^ It is not the organ, that is, the nature and form of the parts
of the body, which have given origin to its habits and peculiar
functions, but it is, on the contrary, its habits, its manner of life,
and the circumstances in which individuals from which it came
found themselves, which have, after a time, constituted the form
of the body, the number and character of its organs, and the func-
tions which it possesses."

Several years ago, not having read Lamarck, I characterized
the above hypothesis as the ^Haw of use and effort," * and I have
subsequently formulated the modus operandi of this law into two
propositions. The first of these is, that animal structures have
been produced, directly or indirectly, by animal movements, or
the doctrine of Icinetogenesis ; the second is, that as animal move-
ments are primitively determined by sensibility, or consciousness,
consciousness has been and is one of the primary factors in the
evolution of animal forms. This is the doctrine of arclicBsfl^ci-
ism. The doctrine of kinetogenesis is implied in the speculations
of Lamarck in the following language ('* Philosophie Zoologique,"
ed. 1830, p. 239): *'With regard to the circumstances which
[Nature] uses every day to vary that which she produces, one can
say that they are inexhaustible. The principal arise from the
influence of climates ; from diverse temperature of the atmos-
phere and of the environment generally ; from diversity of loca-
tion ; from habits, the most ordinary movements, and most fre-
quent actions," etc. The influence of motion on development is
involved in Spencer's theory of the origin of vertebrae by strains ; \
and I have maintained the view that the various agencies in pro-
ducing change mentioned by Lamarck are, in the case of animals,
simply stimuli to motion. \ The immediate mechanical effect of
motion on animal structure has been discussed in papers by Eyder,

* " Method of Creation," " Proceedings American Philosophical Society,'' 1871, p.
247.

\ "Principles of Biology," II, p. 195.

X " On the Relation of Animal Motion to Animal Evolution," "American Natural-
ist," Jan., 1878.

424 METAPHYSICAL EVOLUTION".

Hyatt, eleven ger, and myself, and I have cited the evidence of
vertebrate paleontology as conclusively proving such an effect." *

The object of the present paper is to pursue the question of the
relation of sensibility to evolution, and to consider some of the
consequences which it involves. It is scarcely necessary to observe
that, in the early stage which the subject presents at the present
time, I can only i^oint out the logical conclusions deriyable from
facts well established rather than any exj^erimental discoA^eries not
already known. And I will say here to those who object to the
introduction of metaphysics into biology, that they can not logic-
ally exclude the subject. As in one sense a function of nervous
tissue, mind is one of the functions of the body. Its phenomena
are everywhere present in the animal kingdom. Moreover, when
studied in the inductive, a posteriori method, metaphysics is an
exact science. As Bain observes, it is a good deal easier to fore-
tell the actions of a man than those of the weather. It is only
want of familiarity with the subject which can induce a biologist
to exclude the science of mind from the field.

For the benefit of those who are not familiar with the doctrine
of archaesthetism, f I give an outline of its implications. In the
first place, the hypothesis that consciousness had jolayed a leading
part in evolution would seem to be negatived by the well-known
facts of reflex action, automatism, etc., where acts are often un-
consciously performed, and often performed in direct opposition
to present stimuli. But while it is well understood that these
phenomena are functions of organized structure, it is believed
that the habits which they represent were inaugurated through
the immediate agency of consciousness. It is not believed that
a designed act can have been performed /or the first time X without
consciousness on the part of the animal of the want which the
act was designed to relieve or supply. This opinion accords with
our knowledge of ourselves, and, by irresistible inference, with our
belief regarding other animals. From such familiar observation
we also know that so soon as a movement of body or mind has
been acquired by repetition, consciousness need no longer accom-
pany the act. The act is said to be automatic when performed

* " The Evidence for Evolution in the History of the Extinct Mammalia," Am.
Ass. Adv. 8ci., 1883, p. 32.

f "American Naturalist," 1882, p. 454.

X The same view is expressed by Ribot, " Diseases of the Will," p. 38 (Humboldt
Libr.).

ON CATAGENESIS. 425

witliout exertion, either consciously or unconsciously, and in those
functions now removed from the influence of the unconscious
mind such acts are called reflex. The origin of the acts is, how-
ever, believed to have been in consciousness, not only for the rea-
sons above stated, but also from facts of still wider application.
The hypothesis of archsesthetism then maintains that conscious-
ness as well as life preceded organism, and has been the jjrimum
mobile in the creation of organic structure. This conclusion also
flows from a due consideration of the nature of life. I think it
possible to show that the true definition of life is, enei^gy directed
hy sensihility, or ly a mechanism luliich has originated under the
direction of sensiMUty. If this be true, the two statements that
life has preceded organism, and that consciousness has preceded
organism, are co-equal expressions.

II. COls'SCIOUSIi^ESS, EITERGY, AN'D MATTER.

Eegarding for the time being the phenomena of life as energy
primitively determined by consciousness, let us look more closely
into the characteristics of this remarkable attribute. That con-
sciousness, and therefore mind, is a property of matter, is a neces-
sary truth which to some minds seems difficult of acceptance.
That it is not an attribute of all kinds of matter is clear enough,
but to say that it is not an attribute of any kind of matter is to
utter an -unthinkable proposition. To my mind the absence of
tridimensional matter is synonymous with nothingness or abso-
lute vacuity. To say that phenomena have a material basis, is for
me only another way of saying that they exist. It being granted
then that consciousness is an attribute of matter, or a certain
behavior of matter, it remains to trace its relation to energy,
which is here used in the sense of motion. Consciousness is clearly
not one of the known so-called inorganic forces. Objects which
are hot, or luminous, or sonorous, are not, as is well known, on
that account conscious. Consciousness is not then a necessary
condition of energy. On the other hand, in order to be conscious,
bodies must possess a suitable temperature, and must be suitably
nourished. So energy is a necessary condition of consciousness.
For this reason some thinkers regard consciousness as a form or
species of energy. For my own part, in classification, I prefer to
keep very different things apart. To classify consciousness with
heat, light, sound, etc., does violence to my sense of fitness and
to all proper definitions. This is well shown by Prof. Clifford in

426 METAPHYSICAL EYOLUTIOX.

the following passage : *^ It will be found excellent practice, in the
mental operations required by this doctrine, to imagine a train
the fore part of which is an engine and three carriages linked with
iron couplings, and the hind part three other carriages linked
with iron couplings ; the bond between the two parts being made
out of the sentiments of amity subsisting between the stoker and
the guard." * This satire, whether intentionally or not on thfe
part of its learned author, expresses at once the distinctive char-
acter of consciousness in esse and the imjDossibility of dissociating
it from energy in posse. For it is sufficiently clear that while the
conscious feelings of the stoker and the guard could hy tJie7nselves
do nothing for the train, such a state is essential to the energy
displayed by them when they are at work for its benefit. We all
understand the absurdity of such expressions as the equivalency
of force and matter, or the conversion of matter into force. They
are not, however, more absurd than the corresponding proposition
more frequently heard, that consciousness can be converted into
energy, and vice versa.

The energetic side of consciousness, however, may be readily
perceived by a little attention to its operations. Acts j^erformed
in consciousness involve a greater exjDenditure of energy than the
same acts unconsciously performed. The difficulty of a given
piece of labor is in direct proportion to its novelty ; that is, is in
direct proportion to the amount of endeavor we use in its per-
formance. This is another way of saying that the labor is direct-
ly as the consciousness involved. Another evidence of the dynam-
ic character of consciousness is its exclusive and therefore com-
plementary character. Two opposite emotions can not occupy
the mind at the same moment of time. An emotion excludes all
high intellectual work, and vice versa.

But there is no fact with which we are more familiar than that
consciousness in some way determines the direction of the energy
which it characterizes. The stimuli which affect the movements of
animals at first only produce their results by transmission through
the intermediation of consciousness. Without consciousness, edu-
cation, habits, and designed movements would be impossible. So
far as we know, the instinct of hunger, which is at the foundation
of animal being, is a state of consciousness in all animals. This in-
contestable fact is overlooked by the materialists properly so called.

* " Scientific Basis of Morals," Humboldt Library Ed., p. 21.

ON" CATAGENESIS. 427

On the other hand, as consciousness is an attribute of matter,
it is of course subject to the laws of necessity to which matter
and energy conform. For instance, it can not cause two solid
bodies to occupy the same space at the same time, nor can it add
one body to one body and thus make three bodies. No more can
it make ten foot-pounds of energy out of five foot-j^ouuds of
energy, and it can not abolish time more than it can annihilate
space. These are fundamental truths which are overlooked by a
majority of mankind. Moreover, nothing is more common than
to hear life or mind spoken of as though it of itself is a "sub-
stance," and not, as it should be, as an attribute or condition of
substance or matter.

What is, then, the immediate action of consciousness in direct-
ing energy into one channel rather than another ? To take an
illustration : Why, from a purely mechanical point of view, is the
adductor muscle of the right side of the horse's tail contracted
to brush away the stinging fly from the right side of the horse's
body rather than the left adductor muscle ? Why was the con-
traction-provoking energy deflected into the right interspinal
motor nerves rather than into those of the left side ? Why is the
ear of the horse turned forward to catch tlie sound in front of
him and backward to gather the sound coming from behind ?
The first crude thought is, that consciousness supplies another
energy which turns aside the course of the energy required to
produce the muscular contraction ; either as the man with the
rein in his hand turns aside the horse's head, or as the shield he
holds deflects a moving body. But consciousness jt?er 5e, that is,
regarding it in its proper and distinctive definition, is not itself a
force (= energy). How, then, can it exercise energy ? Certainly
no more than the bare good-will of the train hands can pull the
train. Such an explanation is to admit the possibility of making
something out of nothing.

III. THE RETROGRADE METAMORPHOSIS OF EifERGY.

The key to many weighty and mysterious phenomena lies in
the explanation of the so-called voluntary movements of animals.
I sav "so-called," because true will is not at all involved in the
question. I mean the acts directed by consciousness, the acts
which would not take place at all if the animal were unconscious.
That there are many such acts you well know. The explanation
can only be found in a simple acceptance of the fact as it is, in

428 METAPHYSICAL EVOLUTION.

the thesis, that energy can 'be conscious. If true, this is an ulti-
mate fact, neither more nor less difficult to comprehend than the
nature of energy or matter in their ultimate analyses. But how
is such a hypothesis to be reconciled with the facts of nature,
where consciousness plays a part so infinitesimally small ? The
explanation lies close at hand, and has already been referred to.
Energy become automatic is no longer conscious, or is about to be-
come unconscious. That this is the case is matter of every-day
observation on ourselves and on other animals. "What the molec-
ular conditions of consciousness are, is one of the problems of
the future, and for us a very interesting one. One thing is cer-
tain, the organization of the mechanism of habits is its enemy.
It is clear that in animals, energy, on the loss of consciousness, un-
dergoes a retrograde metamorjohosis, as it does later in the history
of organized beings on their death. This loss of consciousness
is first succeeded by the so-called involuntary and automatic func-
tions of animals. According to the law of catagenesis, the vege-
tative and other vital functions of animals and plants are a later
product of the retrograde metamorphosis of energy. With death,
energy falls to the level of the polar tensions of chemism, and the
regular and symmetrical movements of molecules in the crystalli-
zation of its inorganic products. Let us now trace in more de-
tail the energies displayed by animals and plants.

It has been already advanced (see page 425) that the phenom-
ena of growth-force, which are especially characteristic of living
things, originated in the direction given to nutrition by conscious-
ness and by the automatic movements derived from it. There
remain, however, some other phenomena which do not yield so
readily to this analysis. These are : first, the conversion by ani-
mals of dead into living protoplasm ; second, the conversion of
inorganic substances into protoplasm by plants ; and third, the
manufacture of the so-called organic compounds from the inor-
ganic by plants. To these points we may return again. It is
also well known that living animal organisms act as producers, by
conversion, of various kinds of inorganic eneregy, as heat, light,
sound, electricity, motion, etc. It is the uses to which these
forces are put by the animal organism, the evident design in the
occasion of their production, that gives them the stamp of organic
life. We recognize the specific ultility of the secretions of the
glands, the appropriate distribution of the products of digestion,
and adaptation of muscular motion to many uses. The increase

ON CATAGENESIS. 4,29

of heat to protect against depression of temperature ; tlie liglit to
direct the sexes to each other ; the electricity as a defense against
enemies — display unmistakably the same utility. We must not
only believe that these functions of animals were originally used
by them under stimulus, for their benefit, but, if life preceded
organism, that the molar mechanism which does the work has
developed as the result of the animal's exertions under stimuli.
This will especially apply to the mechanism for the production of
motion and sound. Heat, light, chemism, and electricity doubt-
less result from molecular aptitudes inherent in the constitution
of protoplasm. But the first and last production of even these
phenomena is dependent on the motions of the animal in obtain-
ing and assimilating nutrition. For without nutrition all energy
would speedily cease. Now the motion required for the obtain-
ing of nutrition has its origin in the sensation of hunger. So,
even for the first stej)s necessary to the production of inorganic
forces in animals, we are brought back to a primitive conscious-
ness.

To regard consciousness as the primitive condition of energy,
contemplates an order of evolution in large degree the reverse of
the one which is ordinarily entertained. The usual view is, that
life is a derivative from inorganic energies as a result of high or
complex molecular organization, and that consciousness (= sen-
sibility) is the ultimate outcome of the nervous or equivalent
energy possessed by living bodies. The failure of the attempts
to demonstrate spontaneous generation will prove, if continued,
fatal to this theory. Nevertheless the order can not be absolutely
reversed. Such a proceeding is negatived by the facts of the
necessary dependence of the animal kingdom on the vegetable,
and the vegetable on the inorganic, for nutrition, and consequently
for existence. So the animal organism could not have existed
prior to the vegetable, nor the vegetable prior to the mineral.
The explanation is found in the wide application of the ^^ doctrine
of the unspecialized," * so clearly demonstrated by paleontology.
From this point of view creation consists in specialization, an ex-
pression which describes the specific action of the general princi-
ple described by Spencer as the conversion of the homogeneous
into the heterogeneous. To be more explicit, it consists of the

* The term specialized, introduced into biology by Prof. Dana, has been used in
connection with energy in creation by the author, "Penn Monthly," 1875, p. 569.

430 METAPHYSICAL EVOLUTION.

production of mechanism outof no mechanism, of different kinds
of energy out of one kind of energy. The material basis of con-
sciousness must then be a generalized substance which does not
display the more automatic and the polar forms of energy. From
a physical standpoint j^rotoplasm is such a substance. Its insta-
bility indicates weakness of chemical energy also, which suggests
that the complexity of its molecule may be due to some form of
energy not properly chemical. The readiness with which it un-
dergoes retrograde metamorphosis shows that it is not self-sustain-
ing, and furnishes a good illustration of creation of specialized
substances by a running down in the scale of being. Loew and
Bokorny * suggest that 'Hhe cause of the living movements in
protoplasm is to be sought for in the intense atomic movements,
and therefore easy metamorphosis of its aldehyde groups of com-
ponents " ; the molecular movements becoming molar, to use the
language of Lester Ward. The position which I now present re-
quires the reversal of the relations of these phenomena. General-
ized matter must be supposed to be capable of more varied molecu-
lar movements than specialized matter, and it is believed that the
most intense of all such movements are those of brain tissue in
mental action, which are furthest removed of all from molar move-
ments. From this point of view, when molar movements are
derived from molecular movements, it is by a process of running
down of energy, not of elevation ; by an increase of the distance
from mental energy, not an approximation to it.

The fact that the physical basis of consciousness is composed
of four substances, which are respectively a monad, a dyad, a
triad, and a tetrad, doubtless has something to do, as I have sug-
gested,! with its exhibition of this remarkable attribute. It might
be supposed that the presence of carbon had the effect of restrain-
ing the chemical and physical molecular tendencies of the three
other substances. From this standing-ground we may imagine
that other substances besides protoplasm might support conscious-
ness and life. In other parts of the universe, other substances
they would have to be, if consciousness exist there.

The manner m which protoplasm is made at the present tinie
is highly suggestive. It is manufactured by living plants out of

* " Die chcmische Kraftquelle in Icbenden Protoplasma." von 0. Loew u. T. Bo-
korny, Munich, 1882, L

t "Penn Monthly," 1875, p. 574.

ON CATAGENESIS. 43I

inorganic matter, the hydrogen, carbon, nitrogen, and oxygen
contained in the atmosphere and in the earth. As dead plants
will not perform this function, this action is regarded as in some
way due to the presence of life. The energy peculiar to living pro-
toplasm, and derived primarily in part only from the sun's rays,
directs energy so that the complex molecular aggregation proto-
plasm is the result. This is the only known method of manufact-
ure from inorganic matter of this substance. The first piece of
protoplasm had, however, no paternal protoplasm from which to
derive its being. The protoplasm-producing energy must, there-
fore, have previously existed in some form of matter not proto-
plasm. This is also suggested by the fact that it really antagonizes
the chemical forces, and might be called, from this fact, anticliem"
ism. The protoplasm-sustaining energy of animal protoplasm
may be a less energetic derivative, or vice versa. In terms of the
theory of catagenesis, the plant life is a derivative of the primi-
tive life, and it has retained enough of the primitive quality of
self-maintenance to prevent it from running down into forms of
energy which are below the life level ; that is, such as are of the
inorganic chemical type, or the crystalline physical type. A part
of the energy does so run down, as can be seen in the few auto-
matic movements of plants, and the phosphorescence of some.
Also symmetrical crystals are made by some. But M. Pasteur
has shown * that whenever the crystals are of the organic type,
i. e., contain carbon, they are not symmetrical but are unilateral,
or, as he terms them, dissymmetrical. This indicates that the
presence of carbon has restrained a little the absolute symmet-
rical automatism of the formative force.

IV. ORIGIN" OF LIFE ON" THE EARTH.

If, then, some form of matter other than protoplasm has been
capable of sustaining the essential energy of life, it remains for
future research to detect it, and to ascertain whether it has long
existed as part of the earth's material substance or not. The
heat of the earlier stages of our planet may have forbidden its
presence, or it may not. If it were excluded from the earth in
its first stages we may recognize the validity of Sir William
Thomson's suggestion that the physical basis of life may have
reached us from some other region of the cosmos by transporta-

* "Revue Scientifique," 1884, Jan., p. 2.

432 METAPHYSICAL EYOLUTIOK

tion on a meteorite. If protoplasm in any form were essential to
the introduction of life on our planet, this hypothesis becomes a
necessary truth. Here let me refer to the fact that hydrocar-
bonaceous substances have been discoyered in meteorites. Here
also the remarkable discovery of Huggins claims attention.* This
veteran spectroscopist has detected the lines of some hydrocar-
bon vapor in the spectra of interplanetary spaces. The signifi-
cance of this discovery is at once perceived if we believe that
hydrocarbons are only produced under the direction of life.f

Granting the existence of living protoplasm on the earth, there
is little doubt that we have some of its earliest forms still with us.
From these simplest of living beings both vegetable and animal
kingdoms have been derived. But how was the distinction be-
tween the two lines of development, now so widely divergent,
originally produced ? The process is not difficult to imagine.
The original plastid dissolved the salts of the earth and appro-
priated the gases of the atmosphere and built for itself more pro-
toplasm. Its energy was sufficient to overcome the chemism that
binds the molecules of nitrogen and hydrogen in ammonia, and of
carbon and oxygen in carbonic dioxide. It apparently communi-
cated to these molecules its own method of being, and raised the
type of energy from the polar non-vital to tlje adaptive vital by
the process. Thus it transformed the dead mineral world, j^er-
haps by a process of invasion, as when a fire communicates itself
from burning to not burning combustible material. Thus it has
been doing ever since, but it has redeposited some of its gathered
stores in various non-vital forms. Some of these are in organic
forms, as cellulose ; others are crystals imprisoned in its cells ;
while others are amorphous, as waxes, resins, and oils. But con-
sciousness a]3parently early abandoned the vegetable line. Doubt-

* See address of C. W. Siemens, Prest. British Ass. Adv. Science, 1882 ; " Nature/'
1882, p. 400.

•}■ Says Mr. S. F. Peckham ("American Journal of Science and Arts," 1884, p.
105), on the origin of bitumens: "These chemical theories [of the origin of bitu-
men] are supported by great names, and are based upon very elaborate researches,
but they require the assumption of operations nowhere witnessed in nature or known
to technology. . . . In the chemical processes of nature complex organic com-
pounds pass to simpler forms, of which operation marsh gas, like asphaltum, is a
resultant, and never the crude material upon which decomposing forces act."

The fact that many organic compounds are now produced in the laboratory,
does not prove that such substances can be produced without the exercise of a spe-
cies of energy different from the inorganic types with which we are acquainted.

OlSr CATAGENESIS. 433

less all the energies of vegetable protoplasm soon became automatic.
The plants in general, in the persons of their protist ancestors,
soon left a free-swimming life and became sessile. Their lives
thus became parasitic, more automatic, and in one sense degen-
erate.

The animal line may have originated in this wise. Some indi-
vidual protists, perhaps accidentally, devoured some of their fel-
lows. The easy nutrition which ensued was probably pleasura-
ble, and once enjoyed was repeated, and soon became a habit.
The excess of energy thus saved from the laborious process of
making j^rotoplasm was available as the vehicle of an extended
consciousness. From that day to this, consciousness has aban-
doned few if any members of the animal kingdom. In many of
them it has specialized into more or less mind. Organization
to subserve its needs has achieved a multifarious development.
There is abundant evidence to show that the permanent and the
successful forms have ever been those in which motion and sensi-
bility have been preserved, and most highly developed.

This review of the history of living organisms has been epito-
mized in the following language: *^ Evolution of living types is
then a succession of elevation of platforms, on which succeeding
ones have built. The history of one horizon of life is that its
own completion but prepares the way for a higher one, furnish-
ing the latter with conditions of a still further development.
Thus the vegetable kingdom died, so to speak, that the animal
kingdom might live, having descended from an animal stage to
subserve the function of food for animals. The successive types of
animals first stimulated the development of the most susceptible
to the conflict, in the struggle for existence, and afterward fur-
nished them with food."

V. CATAGEN"ESIS OF IXORGAIN'IC ENERGY.

If the principles adopted in the preceding pages be true, it is
highly probable that all forms of energy have originated in the
process of running down or specialization from the primitive
energy.

In the department of physics I am not at home, and touch
upon it merely to carry out to a necessary conclusion the hy-
pothesis presented in the preceding pages. It may be that physi-
cists and chemists may find value in the suggestions which come
from the side of biology. A cursory perusal of the general hy-
28

434 METAPHYSICAL EVOLUTION.

potheses current in these departments shows that the door is
wide open to receive light from this quarter. What can be offered
here is of the vaguest, yet it may suggest thought and research
in some minds.

In the first i^lace, it is highly probable that one of the problems
to be solved by the physicists of the present and future is that of
a true genealogy of the different kinds of energy. In this con-
nection a leading question will be the determination of the essen-
tial differences between the different forms of energy and the
material conditions which cause the metamorphosis of one kind
of energy into another.

In constructing a genealogy of energies, it must be observed
that we will probably obtain not a single line of succession, but
several lines of varying lengths. It must also be remembered
that, as in the forms of the material world, which are their expres-
sion, a greater or less extensive exhibition of all the types remains
to the present day.

That the tendency of purely inorganic energy is to '*run
down," in all excejot possibly some electric operations, is well
known. Inorganic chemical activity constantly tends to make
simpler compounds out of the more complex, and to end in a
satisfaction of affinities which can not be further disturbed excej)t
by access of additional energy. In chemical reaction the prefer-
ence of energy is to create solid precipitates. In the field of the
physical forces we are met by the same phenomenon of running
down. All inorganic energies or modes of motion tend to be ulti-
mately converted into heat, and heat is being steadily dissipated
into space. Therefore the result has been and will be the creation
of the mineral kingdom ; of the rocks and fluids that constitute
the masses of the worlds.

The process of creation by the retrograde metamorphosis of
energy, or, what is the same thing, by the specialization of energy,
may be called catagenesis. It may be denied, however, that this
process results in a specialization of energy. The vital energies
are often regarded as the most special, and the inorganic as the
most simple. If we regard them, however, solely in the light of
the essential nature of energy, i. e., power, we must see that the
chemical and physical forces are most specialized. The range of
each species is absolutely limited to one kind of effect, and their
diversity from each other is total. How different this from the
versatility of the vital energy ! It seems to dominate all forms of

ON CATAGENESIS. 435

conversion of energy, by the mechanisms which it has, by evolu-
tion, constructed. Thus, if the inorganic forces are the products
of a primitive condition of energy which had the essential qhar-
acteristics of vital energy, it has been by a process of specializa-
tion. As we have seen, it is this specialization which is every-
where inconsistent with life.

With these preliminary remarks we may now consider very
tentatively the relations of the different kinds of energy to each
other and to consciousness. In practice it is sometimes difficult
to draw the line between conscious and unconscious states of
energy. One reason is that, although a given form of energy
may be unconscious, consciousness may apprehend the action by
perceiving its results. The distinction is rendered clearer by
the reflection that we can perceive by sight or touch any action
of the body of whatever character The energy of the conscious
type is therefore altogether mental. The relations may be ex-
pressed as follows :

A. Designed (always molecular). Examples.

I. Conscious.

1. Involving effort " Voluntary " acts.

n -Ki ^ • ^ - tc ^ \ Passive perception.

2. Not involvmc^ effort „,

( Conscious automatism.

II. Unconscious.

3. Involving mental process Unconscious automatic.

4. Not involving mental process Eefiex.

B. Not designed.

I. Molecular.

5. Electric,

6. Chemical, )

7 Ph ' 1 \ Crystallific and non-crystallific.

II. Molar.

8. Cosmic.

The only strictly molar energies of the above list are the cos-
mical movements of the heavenly bodies. The others are molec-
ular, although they give rise to molar movements, as those of the
muscles, of magnetism, etc. Some molar movements of organic
beings are not, in their last phases, designed ; as those produced
by nervous diseases.

The transition between the organic and the inorganic energies
may be possibly found in the electric group. Its influence on life,
its production of contractions in protoplasm, and its resemblance
to nerve force, are well known. It also compels chemical unions

436 METAPHYSICAL EVOLUTION.

otherwise impracticable, thus resembling the energy of the pro-
toplasm of plants, whose energy in actively resisting the disinte-
grating inorganic forces of nature is so well known. Perhaps this
type of force is an early-born of the primitive energy, one which
has not descended so far in the scale as the chemism which holds
so large a part of nature in the embrace of death.

Vibration is inseparable from our ideas of motion or energy,
not excluding conscious energy. There are reasons for supposing
that in the latter type of activity the vibrations are the most rapid
of all those characteristic of the forces. A center of such vibra-
tions in generalized matter would radiate them in all directions.
With radiant divergence the wave lengths would become longer,
and their rate of movement slower. In the differing rates of vibra-
tions we may trace not only the different forms of energy, but
diverse results in material aggregations. Such may have been
the origin of the specialization of energy and of matter v/hich
we behold in nature.

Such thoughts arise unbidden as a remote but still a legitimate
induction from a study of the wonderful phenomenon of animal
motion ; a phenomenon everywhere present, yet one which re-
treats, as we pursue it, into the dimness of the origin of things.
And when we follow it to its fountain head, we seem to have
reached the origin of all energy, and it turns upon us, the king
and master of the worlds.

XXI.

THE OEIGIN OF THE WILL.

I. THE defikitio:n" of the will.

Defikitioks of tlie term '"Will," as we find them in meta-
physical writers, are not identical ; and much apparent difference
of opinion depends, as usual, on this diversity of statement. Locke
regards the concepts *^ will "and ** freedom "as entirely distinct
in their nature, and not essentially related to each other. He says :
*^ Freedom belongs as little to the will, as swiftness to sleep, or
squareness to virtue. Freedom to do is one power, will to do is
another : will, a power of the mind exerting dominion over some
part of a man by employing it in or withholding it from any par-
ticular action ; freedom, again, a power which a man has to do or
to forbear doing any particular action." It appears that what
Locke here denominates will is that common activity of the mind
which expresses itself in action, which may be readily considered
apart from the question of choice. This doubtless expressed some-
thing to the metaphysicians of that time, but merely signifies to
the physiologist of the present day the movement derived from
the metamorphosis of nutritive material in the arterioles of the
brain, which when consciously performed are called thoughts and
feelings, and are the necessary precursors of a class of muscular
acts. The question of will properly so called is not yet entered
on at this point. Dr. Willis * elaborates Locke's position in the
following language : *^ But there is, in fact, no one particular
primitive faculty that wills in the human mind ; will is a general
term, and belongs to and is expressive of the activity of each of
the primitive faculties of our nature ; the benevolent faculty being
active, causes us to will to do good and charitable offices ; the rev-
erential faculty being active, to will to feel respectfully or rever-
ently ; the musical faculty active, to will to sing or hear music,

* "Benedict do Spinoza: his Life, Correspondence, and Ethics," 1S70, p. 145.

438 METAPHYSICAL EVOLUTION.

etc. ; and the Vvilling here is necessary ; but whether we yield to
the impulse of the benevolent, reverential, or musical faculty, and
indulge therein their various willings, is not so ; here we are free,
and can yield or abstain as we list." This passage renders it the
more clear that the latter part of Locke's statement, in which he
defines freedom, is that in which he really refers to the will as
generally understood ; and Dr. Willis's assertion of the existence
of our ability 'Ho yield or abstain as we list," grants all that the
advocate of 'Hhe freedom of the will" could desire.

The modern automatic school only avoid discarding the term
will altogether by using it in the sense of Locke's definition.
They make it merely the conscious mental activity that precedes
the act ; the direction of that activity being necessary in its char-
acter; i. e., the result of impinging stimuli. In other words, on
the automatic theory, the spontaneous activity of the body is
directed or deflected by stimuli, whose ultimate form depends on
the existing mental machinery through which they pass. There
is avowedly no room for a self-determination in such a process,
and its existence is therefore denied by this school. Inasmuch as
a faculty of self-determination is what is here understood by the
term will, and the question in the present article is whether there
be or be not such a faculty, the inquiry to which we address our-
S3lves is whether a human will exist or not. Says Dr. Carpenter : *
'' The psychologist may throw himself into the deepest waters of
speculative inquiry in regard to the relation between his mind
and its bodily instrument, provided that he trusts to the inherent
buoyancy of that great fact of consciousness that zue have within
us a self'determiiiing poiuer which we call will, " The existence of
such a faculty is in these words assumed by Dr. Carpenter, but I
have looked in vain in his writings for a demonstration of the
truth of this position. The same is true of the works of many
other metaphysicians.

Will may be considered in two aspects : first, as a control over
the origin of mental or bodily movements ; and second, as a con-
trol over the direction which those movements take. The latter
case is the one chiefly considered here, as the one involved in cus-
tomary definitions of human will.

It need scarcely be added that the concept will is an abstrac-
tion from supposed special exhibitions of it, and represents a sup-
posed mental property.

* " Mental Physiology," p. 28.

THE ORIGIN" OF THE WILL. 439

II. THE iq^ATUEE OF ACTIONS.

The discussion between the advocates of the freedom of the will
on the one hand, and those of the doctrine of necessity on the
other, has often been obstructed by a petitio principii, which
yields the case to the latter side at the outset. This is the dictum
which has often passed unchallenged by both parties, that "■ human
action is the product of the strongest inducement," or, otherwise
stated,. that "the will is the result of a balancing of opposing
motives," or that "the will obeys the strongest motive." This is
simply the statement, in reversed order, of what we might suppose
without examination to be a general truth, viz. : that the motives
which precede the acts which we observe are stronger than all
others at the time. If this proposition be true without qualifica-
tion, there is no further need of discussion, since it involves the
negation of freedom, or of a power of choosing. But as such, it
is an assumption in advance of a conclusion in the case under con-
sideration ; a begging of the question in a clear sense. Such a
position can only be adopted as a result of the fullest investigation
into the phenomena ; it can not be accorded before examination
into the facts.

But the statement may be admitted with this important qualifi-
cation, by which the argument is transferred to another stage of
the subject, viz. : that we do not thereby explain why the induce-
ments to act thus and so, do, in many obvious cases, overbalance
all others in a given human mind. This inquiry is not fruitless,
so long as we have before us every day examples of men acting
differently under identical circumstances. If there be any " lib-
erty," it is exercised at the point of permitting inducements or
motives of one kind to occupy the mind to the exclusion of those
of another kind ; and secondly, such occupation being granted,
freedom might be exercised in removing restraint from the press-
ure of the present motive, so that the act can take place. If there
be no inherent power of controlling the attention, and none of
restraining the pressure of motive, then there is no will in any
proper sense of the word, and man is an irresponsible automaton.
The proof or disproof of this proposition must, however, be the end,
not the beginning, of the discussion.

An inquiry into the origin of actions must be preceded by an
examination into the nature of the acts themselves. The follow-
ing classification is offered, as expressing as nearly as possible their

44:0 METAPHYSICAL EVOLUTIOK

relations to the general developmental position of active beings,
without any pre-suppositions as to their automatic or voluntary
character. It is necessarily assumed that all acts are performed
with reference to the acquisition of pleasure or the avoidance of
pain ; in other words, that all acts are due to motive, and are the
expression of design on the part of the actor. This is as true of
the simplest as of the most complex actions of animals, whether
consciously or unconsciously performed. The movement of the
Amoeha in ingulfing a Diatom in its jelly, is as much designed as
the diplomacy of the statesman, or the investigations of the stu-
dent. And the motive may be the same in all three cases ; viz. :
hunger. But as the unconscious acts have been probably derived
from conscious ones by organization, a fundamental classification
must first recognize their relations to the two necessary terms of
consciousness, the subject and the object. All actions may then
be divided into two classes ; those which are performed witli the
design of securing the pleasure of the subject, and those whose
motive is to secure pleasure for the object as distinct from, i. e.,
opposed to, that of the subject. The tendencies thus defined have
been named, in other connections, the appetent and the altruistic,
and these names may be preserved as equally appropriate for the
present purpose. Actions of the appetent class difl'er according to
the developmental grade of the animal displaying them, or the
grade of the organ of the body to which they are proper. In their
simplest form they are mechanical movements, following a stimu-
lus without the intervention of any rational process ; the end being
attained by movements, whose directions are determined by me-
chanical or physical laws only. Such acts belong to the lowest
type of animals, and are also seen in the organic functions of all
animals ; they may be called the anoesthetic division. They may
be performed consciously or unconscicasly. Acts of another order
are those which, while due to stimuli, are directed by a process of
ratiocination. They are higher than those of the previous order,
because they successfully accomplish their object under changing
circumstances, to which they adapt themselves as the others can
not. Like them they may be performed in consciousness or in
unconsciousness, or in a still higher state of the mind, that of self-
consciousness. The last condition is only possible to animals of a
high order of intelligence, since it not only demands an exercise
of the rational faculty, with reference to objects, but also with
reference to itself — the subject. These three groups form the

TEE OPJGIX OF THE WILL. 441

rational order. The unconscious actions of both tlie anaesthetic
and rational kinds are called '^ reflex ; " and all of them are ** auto-
matic," in so far as they are performed without will ; terms more
fully defined in the following pages. The process of intellection
in unconsciousness is called unconscious cerebration.

Actions of the second great class, the altruistic, demand for
their performance the attributes necessary for the highest of the
appetent class. They require intelligence enough for the percep-
tion of what is the pleasure of the object, and self-consciousness,
to know that that pleasure is inconsistent with its own, or subject-
ive pleasure.

The arrangement may be summarized as follows :
L Appetent class.

-.A J.1 i.- ( Unconscious (reflex).

1. Anaesthetic. 1 ^^ .

( Oonscious.

( Unconscious (reflex).

2. Eational. I Conscious.

( Self-conscious.
II. Altruistic class ; rational and self-conscious.

Under the definition of will above given, it can not be present
in unconscious or reflex actions, and the inquiry is limited to the
conscious groups exclusively. It may then be well to add a few
words on the nature of consciousness.

This faculty is here understood in its broadest sense, namely,
subjective perception. The term consciousness expresses the
knowledge by the subject of the effects of stimuli on itself, which
ranges all the way from the mere sense of contact to, the sense of
an idea. An unprejudiced scrutiny of the nature of conscious-
ness, no matter how limited that scrutiny necessarily is, shows that
it is qualitatively comparable to nothing else. The attempts to
correlate it with the physical forces have so far been utter failures,
although the vital forces, to which it gives direction, are evidently
not excluded from the laws of quality and quantity. The com-
mon hj^pothesis that consciousness is the product of evolution
appears to the writer, in view of this primary fact, to be irra-
tional ; while the converse, that evolution is a product of con-
sciousness, is far more likely to receive ultimate demonstration.
From this stand-point it is looked upon as a state of matter
which is co-eternal with it, but not co-extensive. Itself in its
totality a reservoir of force, it is the source of all physical and
vital forces, with which it has therefore an equivalency of quanti-

442 METAPHYSICAL EVOLUTION.

ties, but not of qualities. Tlie cause of the difference between
conscious and unconscious force must be secondarily due to differ-
ent conditions of matter as to its atomic constitution ; conscious-
ness being only possible, so far as we can ascertain, to matter
which has not fallen into fixed and automatic relations of its
atoms. The condition appears to be one of tension, in which
the automatic (crystalline) tendencies antagonize each other, the
material being all the while in the metastatic condition of nutri-
tion. This idea is parallel to that of Heraclitus, who held that
the essence of all things lay in per|)etual modification, a universal
becoming, an eternal emergence and disappearance.

In accordance with the preceding views, the relations between
consciousness and matter are thus depicted as of a mutually ne-
cessary character, the movements of conscious force involving con-
sequences to itself from which the properties of matter necessarily
preclude its escape.

If we trace the consciousness of animals to such an origin, it
may be asked. Why have not such beings the powers and perfec-
tions of their source, in quality if not in quantity ? The answer to
this query, in view of the fact that they have not such qualities,
is only to be found in an investigation of the nature of memory.
The absence of memory of the past would be equivalent to igno-
rance ; while a new material vehicle might render memory possi-
ble for the future, and thus education, under new surroundings,
create diverse beings from a primal common source.

We must include in our estimation of the distributions of con-
sciousness and forces not our planet alone, nor our system only,
but the universe. Hence Sir William Thompson's idea, that con-
sciousness ("life") was originally exotic to our earth, is an alto-
gether permissible hypothesis.

If there be such a state of consciousness as will, it must have
appeared in course of the evolution of animals, at some point in
the series of the stages of progress through which their mind has
passed. Yet it is maintained by some thinkers that the doctrine
of evolution necessarily excludes the idea of freedom from the
nature of the minds thus produced. The case is, however, in-
volved in that of consciousness, and the investigation of it must
proceed in the same manner. If it has been shown that will does
exist in connection with evolution, we must proceed to discover,
if possible, the relation between the two facts.

The proof of the existence of a freedom, power of choice, or

THE ORIGIN OF THE WILL. 443

will, is found in the origin of the altruistic class of acts, which are
probably only possible to the human species. These have been
above defined as those in which the pleasure of the object, as dis-
tinct from, and therefore opposed to, that of the subject, is the
design of the act. This definition excludes acts for the benefit of
others in which the actor is also gratified, since the motive may
be in that case the pleasure of the subject. No doubt, many gen-
erous acts are of this character, but they were not such the first
time they were performed, since experience of their pleasurable
character had not then been acquired, and the evidence of all
past experience was of a diametrically opposite character. In
other words, the motives already organized in the mind of the
subject were all in favor of the subject. The laws of evolution
render the introduction of a new element of character at this point
absolutely necessary. It is well known that the development of
mind, and through it of all the acts of the first or appetent class,
has been due to the pursuit of pleasure and avoidance of pain on
the part of the subject. The pursuit of an opposite course, by
animals whose pleasures and pains are those of the successful ful-
fillment of the necessary functions of life, or the reverse, would
insure their speedy extinction. Their survival has been due to
their prompt discrimination of favorable and unfavorable con-
ditions through their sensibilities, and the human species, as the
product of evolution, displays these sensibilities in their highest
form. Under these circumstances it is obvious, since none but
the inherited motives, with refinements due to more complex
circumstances, can be found in his mind, that without the inter-
vention of will, an altruistic act is impossible.

It has also been pointed out that such can only be performed
by a being capable of the highest state of consciousness, i. e., self-
consciousness ; in other words, by a being capable of recognizing
its own mental states. Under such circumstance only can it dis-
tinguish the mental states of a being apart from itself, toward
whom the altruistic act is directed.

It being then conceded that will is exhibited in certain human
actions, it becomes important to determine, if possible, the condi-
tions under which it appeared in the course of the evolution of
man.

III. THE ELEMENTS OF MIND.

Prior to considering the origin of states of mind, it is neces-
sary to go over the well-trodden field of its original constitution.

444 METAPHYSICAL EVOLUTION.

There are three primary conditions of consciousness^ which
naturally grade into each other, viz.: pain, indifference, and
pleasure. Consciousness is of one or the other of these types in
all animals. The constant flow of activity, either in movements
of the whole body or of particular 2:)arts of the body, has brought
animals from their beginning into contact with other bodies,
either at rest, or animated by active forces, as light and heat,
which have varied their sensations, rendering them more positive
in each of the three directions named. These sensations soon
cease, leaving consciousness where it was, but not without marks
of their former presence in the organism. They are recorded,
and continue in unconsciousness so long as the organism remains
unchanged. This is the first part of memory, i. e., retention.
Under the influence of what is called cohesion, the impressions
may be returned to consciousness in a less distinct form by the
occurrence of new impressions which have some near relation
with them as to time, place, or qualities of other kinds. This is
the second part of memory, or reminiscence. The sum of the
impressions which are necessar}' to memory constitutes experi-
ence. It is evident that reminiscence is pleasurable or painful,
as the experiences recalled were pleasurable or painful. Another
quality is rendered possible by the two faculties of retention and
cohesion, viz.: classification. This consists of a re-arrangement
of retained impressions in accordance with different kinds of co-
hesions, i. e., different kinds of likenesses. The products of
classification may be brought into consciousness just as sensible
impressions are revived ; but unlike these, they constitute in their
totality a new experience of internal origin. When a cohesion
between two circumstances is due to a repeated experience of the
one as following the other, men entertain the idea that one is
necessary to the other. From memory of the necessary results
of our own activity, we have come to regard necessary sequences
as the result of activity somewhere. If activity be discerned in
the first of two coherent events, we regard it as a cause of the
second : if the first be passive, the idea of cause does not arise in
connection with it, but in some other active agent. Finally, all
processes involving reminiscences are less distinct than the original
impressions. Spencer calls the former /«m^, the loiter distinct ;
the faint order are the processes of reason ; the distinct, of per-
ception.

Whether these processes are pleasurable, painful, or indifferent,

THE ORIGIN OF THE WILL. 445

depends on the characteristics of the reminiscences wliich are
their subjects. As the reminiscence is less distinct than the origi-
nal impression, so there comes to be, as pointed out by Spencer, a
faint order of pleasures and pains, which, with the indifferent class,
form the material of the processes of reason. These mental states
of pleasurable and painful consciousness constitute that primary
diyision of the mind, the feelings or affections, as distinguished
from the intellect.

The feelings co-exist with intellectual operations of all grades
of complication, since pleasures and pains are states which follow
all kinds of activities, and therefore also reminiscences. To seek
pleasure and to avoid pain constitutes the business of the lives of
all conscious organisms ; and hence the feelings, as derived from
exjDeriences, are the directive and often originative conditions of
movements or actions. In animals with higher intellectual powers,
the general classification of experiences of given objects or actions
results in a higher order of the mental feelings, which are called
likes and dislikes. When these forms of consciousness assume an
intense condition due to stimuli, they become emotions or pas-
sions.

These details are entered into in order to show that the feel-
ings in their various grades are the motives of action in all ani-
mals, from the Amcela to man. In the former they are mere
reminiscences ; in the latter they are so generalized as to become
enduring principles of action, which put the intellect to every
conceivable labor. And it is evident, from this foundation fact,
how the intellect itself has been constructed. The activity stimu-
lated by the feelings has resulted in new experiences, and the ac-
cumulation and elaboration of these into new combinations of the
faint type of consciousness, has been the law of their development.
This we can observe in the education of one generation of living
animals, and it has doubtless been the law of the generations of
the past as well. We may then review the probable method of
development of mind through the ages of past time.

IV. THE DEYELOPMENT OF MIND.

In the first place, it is evident that the evolution of mind has
been due to the activity of animal life. Although not asserted, it
is sometimes implied that '^ circumstances," in which the animal
is passive, have been the efficient cause of mental development.
That this could have been the case is inherently impossible, and

446 METAPHYSICAL EVOLUTION.

since animals of the lowest types possess powers of movement,
their activity has necessarily been an immediate cause, while sur-
rounding circumstances have exercised a controlling influence.

Animal activity must be traced to the generation of force or
motion by a protoplasmic body which is constantly supplied with
nutriment. This production of force is the basis of the acts of
animals, up to and including man ; often, as remarked by Prof.
Bain, displaying itself in aimless discharges or playful movements,
as in lambs and boys.

But we observe even in very simple organisms, as the Ammla,
etc., that many movements are not aimless, nor without design.
"We observe that these mere specks of jelly devour nutritious sub-
stances, and reject the innutritions ; that they even distinguish
between the Diatom which contains protoplasm within its shell,
and the empty shell. Many facts of this kind lead us to believe
in the consciousness of these pioneers of life, and seem to show
that they have experiences of the pleasures of nutrition, and of
the pains of retaining insoluble substances in the seats of assimi-
lation. It would also appear that they rememler these sensations,
so as to seek the pleasures and reject the pains, when in the course
of their wanderings they again come into contact with the ma-
terial objects which have caused thenl. Given these two terms,
sensibility (consciousnsess) and memory, and we have the con-
ditions by means of which the entire complex superstructure of
the affectional and the intelligent acts has been elaborated out of
mere movements.

This has been accomplished by the well-known laws of organi-
zation of habits, and heredity. The performance of an act under
stimulus so modifies the structure of the bioplasts of the brain as
to facilitate its repetition. With further repetition the organiza-
tion is soon complete, and action follows the stimulus without
direction, so long as no adverse influence affects the consciousness.
Whether the act be one of the Rational or Anaesthetic orders, from
this habitual stage it becomes automatic in the true sense, between
which and the reflex act no line can be drawn. It is evident that
the degree of consciousness present in animals will depend on the
number of changes appearing in their surroundings, whether due
to modifications of the external world, or movements of their own
bodies. Inasmuch as the habits of the lower animals are few and
simple, most of them must be automatically performed, the con-
sciousness being only present at the commencements of the several

THE ORIGIN OF TOE WILL. 447

processes. It is probable tliat the organization of mental functions
was at the first identical with the so-called organic functions,* so
far as they consist of mechanical movements ; and that the latter
early became reflex and devoid of consciousness, developing sub-
sequent forms through mechanical causes. The organization of
mental functions, on the other hand, was by continued education,
which requires the presence of consciousness at every step.

The well-known fact of the inheritance of mental qualities
shows that the evolution of mind has advanced by a continued
process of accumulation as the product of animal experiences.
The new generation has inherited the organization of the old, and
all the reflex and automatic activities entailed by it, and has pro-
ceeded in proportion to its activity to acquire new experiences,
habits, and organization.

V. THE BEGII^NIXGS OF DEVELOPMENT.

(a) The Feeliiigs.

The intellectual faculties of every animal thus belong to two
classes : first, those which have been inherited ; and second, those
which it has acquired by its own experiences. Of course 4:)rogress
consists in accessions to the latter class, since inheritance without
addition is mere repetition. If no acquisitions were made, or to
be made, the mental, i. e., the cerebral organization inherited by
animals would continually repeat the form of their actions as un-
erringly as the nature of a machine gives the character to the
movements propagated through its wheels and cranks. That
much the larger proportion of animal acts are of this class, that
is, are automatic, there can be no room to doubt. With an im-
petus to movement given, the strongest liking or disliking selects
the object or direction, and the reason furnishes the mode of ac-
quisition or avoidance. The known past teaches of the unknown
future, and the established circle of the functions of life is ful-
filled. But without acquisitions, development is impossible.

Acquisitions to experience are gained by movements of the
body, and hence by the mental activity to which the latter are
due. But it is evident that the primary movement has preced-
ence in the order of time over the feeling which deflects it, or
the experience which directs later actions. In the lowest animal

* See " On Consciousness in Evolution, " "Pcnn Monthly," 1875, Aug., where
this view' is held.

4^8 METAPHYSICAL EVOLUTION.

the first movement was doubtless a mere discliarge of force ; but
the first designed action, the appropriation of food, was due to a
sense of want or hunger, which is a form of pain. This was fol-
lowed by gratification, a pleasure, the memory of which consti-
tuted a motive for a more evidently designed act, viz. : pursuit.

These two mental states, the one painful, the other pleasurable,
form the basis in the feelings of all appetent acts. The painful
sense of want is the motive to the performance of the jDrimary
class of actions, and the experience of pleasurable gratification fur-
nishes the motive for a class which must be regarded as secondary.

The primary organized feelings of animals are not numerous.

In man, the most highly developed. Prof. Bain enumerates *
only eleven types, and some of these he states may be further re-
solved. From the stand-point of the evolutionist this is evidently
necessary, and a corresponding reduction in number can be made.
The develoiDment of the feelings has proceeded from the early be-
ginnings above described, in subsequent ages, pari passu with that
of the intellect. It is necessary in the nature of things that it
should be so, since the finer and fuller the sensibility to pleasures
and pains in all directions, the greater will be the complexity of
experience, and hence of intelligence. It is not practicable to
trace the history of the feelings here, but I allude briefly to one
class of them — the social affections — as they have been treated by
Herbert Spencer, whose contributions to this department of
knowledge have been very important.

This author maintains that the social affections are the product,
in the department of mind, of the function of reproduction.
They are the organized products of experiences of pleasures de-
rived from fellow beings, just as other kinds of likes and dislikes
are derived from experiences of the qualities of various objects.
It is sufficiently evident that this faculty must survive, and the
social instincts become more and more refined or specialized. It
is a remarkable fact in the successional relations, and hence evo-
lution, of the vertehrata, that the only system that has accompa-
nied the nervous in its progress from generalization to specializa-
tion and perfection, is the reproductive. Man, standing at the
head of the series by his develojDcd brain, possesses also the most
specialized reproductive system. He is inferior to many other
Mammalia in his osseous and muscular type, and in his digestive

* " The Emotions and the Will," p. 36.

THE ORIGIN OF THE WILL. 449

organs, including dentition, etc., but the orders wliicli are his
superiors in these respects yield to him the supremacy in the two
systems mentioned.

Functionally the two systems oppose each other, and that
exercise of the one is at the exjoense of the other is a physiological
law. Health of the individual, and persistence of the species,
depend on the maintenance of the equilibrium between them.
This is because success in obtaining food on the one hand depends
on intelligence, and undue power can not be expended in other
directions without starvation. Thus the law of evolution lends
full support to the doctrine first formulated by Kant, of the dual
nature of the human mind, in its division into the intellect and
the affections.

(b) In the Intelligence.

The intellect includes a record of experiences of resemblances
and differences, of causes and effects, arranged in orders of place,
time, and of qualities of all kinds. The importance of an intellect
depends on the number of experiences it contains ; on the clear-
ness with which qualities can be brought into consciousness ; on
the correctness with which the classification expresses the quali-
ties ; on the relation which the qualities preferred bear to an ob-
ject of pursuit ; and on the rapidity with which any or all of these
functions may be performed. The triumph of reason is foresight
or predication, in which it brings into consciousness the unknown,
by reproducing its experiences of the known. This is the serv-
ice rendered by education, by the acquisition either of experiences
themselves, or of the experiences of others.

Acquisitions then do not imply a predication of the unknown
from the known, but an actual addition to the stock of the known.
The automatic life above described includes no such process, but
is a routine varying only in unimportant details, and changing in
no great feature. Progress evidently depends on something be-
sides knowledge, for in proportion to the degree of progress is the
departure from the known, and in proportion to the novelty of a
situation is experience worthless as a guide.

Designed actions which are performed without a basis of knowl-
edge which is sufficient for predication are not automatic. That
is, while the activity may be physically spontaneous and comi)ul-
3ory, the direction it takes and the mode of its execution can not
be automatic, unless the machinery which must give the direction,
and which creates the mode, be already in existence.
29

450 METAPHYSICAL EVOLUTION.

The field of the known is very limited, as compared with that
of the unknown, in the experience of the Amcela. In its first
movements, it has absolutely no basis on which to establish an
anticipation of the future. Such is also the situation of the young
of every animal. But the cases of the inferior and superior spe-
cies present the important difference that in the former there
exist few or no mental powers derived by inheritance, while in
the latter such are present in proportion to the position of the
species in the scale of intelligence.

The facts of evolution teach that the habits of animals have
been modified during past geological ages, under the influence of
changes in their physical surroundings. While these changes may,
perhaps, have furnished the stimuli to the adoption of new habits,
the conditions have not often been so rigid as to define exactly
what those habits should be, in some or all of their details. The
animal has necessarily proceeded blindly in many instances ; in
others, his mental darkness has been illumined by a low grade of
imagination. This may be believed in view of the many attempts
which animals often make before succeeding in attaining a desired
end. Imagination plays an important part in the origin of mo-
tives and of actions, and is related to predication. It is defined
as the presentation or construction of images or representations
from items of experience, which representations so far differ in
the connection of their details from actual experience, or so far
lack the qualities of experiences, as not to constitute a predica-
tion of future events. Predication mav be defined as the certain
knowledge of the unexperienced from the experienced ; while
imagination includes the grades of probable, possible, and impos-
sible concepts, constructed from the same material as predication.
Whether this faculty exists in the animals which can not speak,
is not readily ascertained ; but, inasmuch as many of them predi-
cate, it is probable that they possess some degree of imagination
also. But it is obviously a quality of the highest types of mind,
since its development depends primarily on the furniture of mem-
ory, derived from a long period of experience, whose amount de-
pends on receptivity and retentiveness.

YI. THE OEIGIi^ OF MOTIVES.

It has been said that the operation ordinarily called choosing,
in which the will is popularly supposed to be free, consists merely
of a sum in addition and subtraction, where various inducements

THE OPJGIX OF THE WILL. 451

are balanced, the resultant preponderance being expressed in the
act. It will be easily seen that while this statement is true in re-
gard to cases where the elements of the calculation are known, it is
not true where any or all of them are unknown. The difference
in the two cases is very great. All likes and dislikes are based
upon experience or knowledge ; and when there is no knowledge,
likes and dislikes can not be said to exist. Since likes and dis-
likes constitute motives, where the former are wanting the latter
are also wanting. Whatever inducements are presented from be-
yond the field of knowledge are derived from the imagination,
and are in self-conscious minds relatively weak as motives, or
absolutely without weight. They might be regarded as motives
in embryo, ready to become such on the acquisition of a corre-
sponding experience. The imagination can prefigure one alterna-
tive as well as another, in a direction wdiere experience is wanting,
and might indeed be said under such circumstances to have no
existence, and the expression, ^'1 can't imagine," be thought to
have foundation in fact. The influence of such a guide is not
imperative, and raises no obstacle to the origin of a new feature
of consciousness by an act of choosing, when the pressure to act
at all is sufficiently great.

There is, perhaps, but one situation of the mind where the
pressure of feeling is strong enough, and predication and imagina-
tion sufficiently excluded, to develop a will which shall create
motives rather than obey them. This is in the cases where self-
interest is weighed in the balance against the interest or good of
other people. Here the feelings are most severely ju-essed, and
the future results to self most uncertain. Self-sacrifice may be
beneficial to self, or it may not : one may be the gainer by the
general prosperity, or he may be the loser. Morality may promise
future good to the community, but why sacrifice self for the com-
munity ? Gratitude for services rendered is an uncertain antici-
pation. Man's most limited knowledge and greatest inability in
predication is in the field of human motives and actions, and
chiefly in respect to those which belong to his moral feelings. As
already remarked, the complication in this direction is so great as
to produce the effect of novelty : so that man, come into posses-
sion of an intellect which is the product of ages of development,
finds before him a new field of his own making, where his in-
herited powers fail.

This is the field where the most momentous decisions possible

452 METAPHYSICAL EVOLUTION".

in human life are made. Since questions of right and wrong re-
late to the happiness of men in their relations to each other, the
social affections are the stronghold of the motives that bear on
this result. It is evident that a thousand subordinate motives
take their direction from the primary decisions between these two
original alternatives of feeling.

It is true that the predication of human actions, necessitated
by bodily functions alone, is eas}^ even when' they come to be of
a highly complex character, as in the mercantile transaction of a
populous business center. But so soon as the ethical element
enters into the calculation the difficulty is greatly increased, and
with the majority of men predication ceases, and faith begins.
This is illustrated in the many credit transactions, without which
it is well known that trade on any but the most limited scale is
impossible. So it must be admitted that many men practice faith
in many affairs, and that this faith is chiefly reposed in the moral
excellence of other men. Under these circumstances, that state of
the affections arises in most men which is termed faith, and which
is only present in the highest form of progressive action, whether
the results of tliat action be beneficial or not. It is a condition of
the affections, as imagination is a condition of the intellect. The
lowest animal, when attempting a novel act in obedience to im-
perative stimuli, doubtless moves blindly, and adopts one of two
or more alternatives through pure accident. In animals of a
higher grade of intelligence, new situations are known to be such,
and fear or suspicion is the usual result. Generall}^, animals of the
higher orders do not adopt new habits excepting under severe press-
ure, and the majority of them have perished, in past geologic ages,
on account of their inability to assume new modes of life. Never-
theless, in so far as an animal or a man ventures into an unknown
field of action, where he is without the guidance of a past ex-
perience, he or it performs an act of trust in the broad meaning
of the word. So far as this state of mind is known to the subject,
the act is one of true faith in the restricted or proper sense of the
word. Imaginations may and do assume to men the importance of
truths, and in so far they are such to them. But in proportion
as this is the case, faith in its proper sense is wanting, and the
action following is automatic. The highest form of intellect is
necessary to the highest form of faith, since it is only by a knowl-
edge of the absence of knowledge that an act of faith is possible.
In proportion to this knowledge of self is faith enlarged ; in pro-

THE ORIGIN OF THE WILL. 453

portion to certainty, or supposed certainty, in affairs, is faith
diminished in its scope.

It is evident then that, abstractly speaking, occasions must
arise in human experience where a decision between two alterna-
tives is dependent on choice alone. That these occasions have
arisen, and the choice been made, is shown by the existence of the
altruistic class of actions. The number of these occasions may
not be very great, but the consequences are ver}' important. In
whatever direction these decisions are made, long series of auto-
matic actions are organized.

Although the existence of the altruistic class of acts affords the
clearest proof of the origin of will, it is not denied that corre-
sponding situations may not occur in other directions. It is also
probable that will, once organized as a faculty of consciouness,
can be exercised in many acts in opposition to habits, differing in
accordance with the constitution of the individual ; and that it
can be inherited like any other quality of mind. But I will show
later, that the organization of altruistic habits has narrower limits
than that of those of the appetent class, because self-preservation
depends on the latter, and not on the former, so that the appe-
tent qualities are more certain to be inherited and survive.

The conclusion of this portion of the subject is, that that de-
partment of mind called the feelings * is the primary source of
action ; that they act automatically, with or without the aid of the
reasoning powers, when dealing with the known ; but when deal-
ing with the unknown may develop, in self-conscious beings, the
state of faith and acts of will ; that this freedom is born of ten-
sion of the affections and of inability of the intellect.

Thus have the irregular and fortuitous decisions of animals
been replaced by volition, as the highest quality of the mind, and
therefore the crown of evolution. No new " physical '' force is
here called into requisition. The determination of the direction
of such forces already existing in or passing through the brain in
executive action need not add to nor substract from them. Will is,
under these circumstances, looked upon as developed consciousness.

All this is, of course, opposed by the doctrine of the origin of
moral excellence by development, on the basis of the utilitarian
theory of morals. I therefore proceed to a brief examination of
its claims in this direction.

* Which appears to be identical with what Schopenhauer calls the will.

4:54: METAPHYSICAL EVOLUTION".

Good is well defined as tlie greatest happiness of the greatest
number ; and by a natural transfer, the term is applied to what-
ever is conducive to that object. It therefore includes not only
present pleasures, but also the influences which conduce to future
pleasures, and which may be sown in the mind long before they
bring forth fruit. As present pleasures are not always consistent
with greater ones in the future, so present pleasure is not always
good. Evil being the reverse or negation of good, or happiness, is
avoided by all beings to whom it is consciously known ; but what
they regard as evil will of course depend on their intelligence in
determining or predicating the future effects of actions. But no
matter what the degree of intelligence, no responsibility, as usu-
ally understood, can be expected of beings which have no power
of choosing, or will.

The utilitarian theory of the evolution of morals asserts that
the development of goodness is simply due to the discovery and
enforcement of the law of self-jirotection and preservation. The
selfish interests require the protection of person and property,
without which a community is an impossibility. Law being thus
established and enforced, moral habits are imposed ujDon men,
which become incorporated into character and transmitted to suc-
ceeding generations. This is all doubtless true, but whether it is
a fundamental or secondary truth is the point requiring attention.

The fundamental objection to this hypothesis is, that the al-
truistic affections are not inherited or transmitted. This is be-
cause the pains and penalties of wrong-doing as inflicted by law,
can not (and ought not to) overcome the inherent instinct of self-
preservation in man. It is true that moral character is inherited,
and that changes in this department for better or worse are trans-
mitted to offspring. The mental organization of a race may be
improved by the weakening of the emotional or the strengthen-
ing of the rational faculties. But since the affections are at the
foundation of all activity whatsoever, of right-doing as well as of
wrong-doing, it is obvious that no amount of legal restraint can
render them innocuous. Their existence is necessary for self-
preservation, and law only restrains their activities to certain di-
rections. That intelligence tends to restrain wrong-doing is true ;
but although intellect is inherited, the manner in which its teacli-
ings are applied in practice is not. Each man must learn the
merits of different courses of action in regard to morals for him-
self ; his intelligence places before him the facts, and shows him

THE ORIGIN OF TUE WILL. 455

how to execute his wishes, but the state of his affections deter-
mines the direction of his acts. Moral amelioration has attended
the progress of intelligence on the one hand, and moral abase-
ment on the other. Intelligence is the condition of the perception
of moral truth ; in other words, intelligence, as applied to moral
questions, is the conscience. Consequences of acts are understood,
and their relations to the pleasures and pains of men are weighed.
Thus, no doubt, the world has advanced in the knowledge of good
and evil, and of right and wrong. That it has improved in the
practice of right has not been due to the inheritance of respect
for law, but to the self-destructive nature of wrong. That con-
tinued wrong sooner or later ends in the destruction of the wronc:-
doer, either from within or without, must be generally admitted.
Thus is the truth of the doctrine of '^ the survival of the fittest "
vindicated in moral as in natural law. But it is also true that
this law is restrictive onl}^, and that the school of Hume and
Bentham has overlooked the deeper originative law in moral phi-
losophy, as the school of Darwin has done in biological philosophy.

It may still be urged that, if it be granted that experience of
the pains of evil-doing be not transmitted as an intellectual ac-
quisition from generation to generation, nevertheless such experi-
ence is sufficient to educate each separate generation as it passes,
without any other than automatic action on their part. It may
be replied to this that the results thus obtained are not due to
will, but simply follow compulsion, the motive thus created only
varying in strength with the characters of the individuals. Its
success is restricted to circumstances where the j^enalties are suffi-
ciently certain to constitute counter-inducements to effect the
necessary restraint. This can only be the case with the weaker
members of society. Wherever there is sufficient power to escape
penalties, wrong-doing has no restraint. Under such a system
might and right are identical ; for the strongest needs no protec-
tion of law. It is true that society can combine against a single
malefactor, but it is also true that malefactors can combine. In
fact, it is one of the usual phenomena of human society to find
men becoming malefactors as soon as they attain to power ; or to
find society governed by a few malefactors who have an army to
enforce their pleasure.

While then inheritance does not secure the performance of
altruistic acts, appetent affections maybe so increased by accumu-
lation in descent as to become uncontrollable, so that will either

456 METAPHYSICAL EVOLUTIOK

does not come into existence, or is extinguished, so far as regards
those affections. In such a situation there is no such equivalency
between opposing motives as gives opportunity for the will, the
experience of appetent pleasure being too strong to allow of hesi-
tancy in the face of vague representations of imaginary conse-
quences on the other side. Even in highly intelligent men, to
whom consequences are best known, knowledge may be thrust
from consciousness, by strong feeling in favor of one alternative
at the moment of action.

YII. COl^SEQUEIirCES.

It is now w^ell to consider how far an automatic mind has any
claim to personality or individuality, as generally understood.
From the usual stand-point, a being without 'liberty," or will
properly so called, is without character, and is in so far a nonen-
tity. Even the character of the Deity can not escape this de-
structive analysis ; for according to Spinoza, if He is good, but a
single line of action, without alternatives, lies open to God, if He
be at the same time omniscient. All this is changed if the ele-
ment of spontaneity in character be presupposed. The existence
of such a quality in man renders foresight of its decisions in some
cases no more than a calculation of chances, and in other cases
impossible ; thus offering the only conceivable limit to omnis-
cience, and hence to omnipotence. And as we regard the good-
ness of God as the anchor of the universe, if that goodness be in
some respect inconsistent with omnipotence, we are strengthened
if we discover that there is ground for correcting our traditional
suppositions in regard to the latter. Can we not find this ground
in a liberty or freedom which is the condition of what we suppose,
in the absence of knowledge, to be the characteristic of the highest
class of conscious existences ?

Note. — Another explanation of this conclusion of Spinoza's, quite apart from
the question of human freedom, is to be found in some of the necessary properties
of matter. The old theologians expressed this point obscurely in their phrase, " the
intractability of matter." (Ed. 1886.)

Second Note. (Ed. 1886.) — The preceding essay was written several years
prior to that on Catagenesis. In the latter article a mental quality was referred to
as present in all animals, which constitutes " the will " of various writers, although
it is not free. It is described in the following passage : " Why, from a purely me-
chanical point of view, is the adductor muscle of the right side of the horse's tail con-
tracted to brush away the stinging fly from the right side of the horse's body, rather
than the left adductor muscle ? Why was the contraction-provoking energy deflected

ON THE ORIGIN OF THE WILL. 457

into the right interspinal motor nerves rather than into those of the left side ? "
The conclusion was that this phenomenon can not be explained on purely mechani-
cal principles ; but that it required the assumption of the thesis that " energy can
be conscious." {Supra, p. 427.)

Further thought on this subject shows clearly that this conscious state of energy
is self-directive in accordance with the lessons of experience, but without being
necessarily free in the sense referred to in the preceding essay. In Mammalia the
current of energy derived from stimulus, after reaching the cortical cells of the an-
terior cerebral lobes, issues from them in a direction appropriate to the needs of
the animal, having undergone a deflection or determination within them. This
capacity for " design " is peculiar to beings which can be conscious, and constitutes
the most important proof in evidence of a degree of control of mind over matter.
The evidence strongly suggests that this control is greatest when the environment
is simple or generalized, since motives are then relatively simple.

Note to Catagenesis by the Author, 1886. On p. 434 reference is made to
the fact that " in chemical reaction the preference of energy is to create solid pre-
cipitates." This fact is but one illustration of the law of thermo-chemistry that
*' in any reaction, those bodies, the formation of which gives rise to the greatest de-
velopment of heat, are formed in preference to others." This is a retrograde meta-
morphosis of energy, or catagenesis.

IS"DEX.

Acceleration, vi, 142, 182, 287, 383.

Acceleration and retardation, 2, 11, 125,
127, 297.

Acrania, 322, 323.

Actinia, 33,

Actinophrys, 27, 187, 192.

Actinopteri, 325, 326.

^sthetophore, 419.

Aethalium, 396.

Agassiz,vii, 8, 45, 58, 60, 61, 62, 83, 91,
92, 103, 121, 124.

Ageniosus, 327.

Allen's "Anatomy," 272, 279.

Allen, H., 115, 242.

Allen, Keen, and Pepper on " Universal
Hyperostosis," 183.

Allman, Prof., 415,

Altruism, xi, 237, 441, 453.

Amhlydomis sinosus, 375.

Amblyopsis, 196.

Amblypoda, 278, 342, 343, 344, 346, 348,
360, 368, 371, 374,

Amblystoma, 4.

Amblijstoma mavortium^ 88.
tigrhmm, 89.

Ameiva pleii, 87.

American Association for the Advance-
ment of Science, x, xi, xii, xiii.

"American Naturalist," ix, xi, xii, xiii,
244, 277, 359, 363, 383.

Ametabola, 316.

Aniiui'us, 4.

Amiurus albidics, 85.
lynx, 85.

Ammocoetes, 316.

Ammonites, 18.

Amoeba, 440, 445, 446, 450.
Amoebodonts, 247, 248, 257.
Araphioxus, 182.
Amphiuma, 333.
Anaptomorphus cemiilus, 279.

homnnculus^ 279.
Ancestral types of mammalia cducabilia,

266.
Anchitherium awclianense, 275.
Ancisfrodon cordortrix, 197.

piscivorus, 197.
Anelytropidae, 337.
Anguidae, 337.
Aniellidae, 337.
Anisonchus, 245, 359.
Anolis, 4.

Anoplotberium, 247, 265, 370.
Anthracotherium, x.
Anthropoidea, 342, 343.
Antiarcha, 323.
Antilocapra, 383.
Antiodonts, 247.
Anura, 331, 332, 333.
Aphelops meffalodvs, 369.
Aphododiridae, 328.
Appendicularia, 322.
Archcelu7'us dibilis, 375.
Archaesthetism, xii, 406, 414, 419, 421.
Arcliaeopteryx, 340.
Arcifcrous anura, 95, 218.
Artiodactyla, 344, 368, 371-374, 375,
399, 401.
omnivora, 199.
Ascertained cases of transition, 87.
Ascidia, 399.
Atrophy, 13, 127.

4:60

INDEX.

Aturia, lY.

Australian native, 291.
Avian line, the, 340.

Bain, Prof., 446, 448.

Baird, S. R, 55, 85, 87.

Barnard, 205.

Bascanium constrictor, 197.

Bathmism, 26, 205, 226, 414.

Bathmodonts, 248, 259.

Batrachia, 351.

Batrachia anura, 46, 216, 332.

Beginnings of development, the, 447.

Bennett, Alfred, 199, 214.

Bentham, 455.

Bokorny, 430.

Borborocoetes, 4.

Bos, 348.

Bothriolepis canadensis, 323.

Boulanger, 337.

Bibron, 95.

Bidens frondosa, 86.

BischofP, 290.

Brachiopoda, 399.

Branchiostoma, 322, 384.

Bridger fauna, 302.

Broca, 290.

Bronn, Prof., 45, 51, 102.

Bufoniformia, 217.

Bunodont type, 243.

Bunotheria, 343, 346, 349.

Buteo, 4.

Calamodon, 278.

California Academy of Sciences, xi.

Caraelidae, 375.

Canidae, 246.

Cams familia.i'is, 224.

Caprimulgidae, 341.

Cariacus virginianus, 50, 177-178,

macrotis, 178.
Carnassial bunodonts, the, 251.
Carnivora, 264, 278, 344-346, 348, 399-

.401.
Carpenter, Dr., viii, 191, 206, 438.
Casts of brain-chambers of extinct mam-
malia, figures of, 308.
Catagenesis, xiii, 422, 428, 434.

Caudisona, 4.
Causes of evolution, 14.
Cebidae, 180.
Cebus apella, 12.

capucinus, 12, 38.
Celestics pJioxinus, 84.
Cell-repetition, on, 185.
Centetes, 360.
Centetidas, 348.
Centrotelma geograpldcum, 85.
Cephalizatiou, 39.
Cervidae, 177.

Cetacea, 26, 342, 343, 347, 349, 399.
Chaenobryttus viridis, 213.
ChEetodontidas, 330.
Chamcesaura angiiina, 84.
Change in amount of growth-force, 200.
Characinidae, 327.

Character of higher groups, of the, 132.
Chelyosoma maclovianum, 323.
Chiromys, 180, 202.
Chiroptera, 342, 343, 344.
Chorophilus, 4.
Chrondrostei, 325, 326.
Cinclidium maximum, 85.
Cladodonts, 325.
Clark, H. J., 167.
Clepsydrops, 363.
Clevenger, 424.
Clifford, Prof., 425.
Coelenterata, 182, 413.
Coenogenesis, 126.
Cohnheim, 195, 406.
Coleoptera, 316.
Colocephali, 327.

Comparison of the opposing series, 250.
Complementary diminution of growth

force, viii.
Condylarthra, xiii, 342-6.
Consciousness, energy, and matter, 425.
Consciousness in evolution, x, xii, 390.
Coranus suhapterus, 89.
Coreopsis discoidca, 86.
Correlation of physical and vital forces,

191.
Corvus, 4.
Coryphodon, 270, 272, 273, 274, 276, 369,

374.

INDEX.

4G1

Coryphodon elephantopiis^ 2G9.
Coryphodontidae, 359.
Cosoryx, 224, 271, 376.
Crania of anura, 222.
Craniata, 322, 323.
Creodonta, 359, 365.
Cretaceous fauna, 302.
Crossopterygia, 325, 326.
Crotalus conjluentus^ 212.
Cuvier, 8, 88, 124, 129, 146, 176
Cyclopterus, 331.
Cyprinidse, 327.

Dana, J. D., 39, 429.

Darwin, Charles, 2, 3, 11, 13, 15, 42, 106,

124, 174, 405, 409, 455.
Daubentonioidea, 342.
Deltatherium ftmdaminis, 362.
De Serres, Prof., 74, 77.
Desmognatlms jusca, 87.

nigra, 87.
Deuterosaurus, 363.
Development of the fine arts, 153.

of intelligence, 149.

of mind, the, 445.
Developmental relation of generic to

specific characters, 82.
Developmental significance of human

physiognomy, 281.
Diadectidae, 335.
Dibamid^, 337.
Didonius mirabilis, 338, 339.
Didelphys, 360.
Didymictis protemcs, 215.
Dimorphodon, 335.
Dinidis cydops, 366.
Dinocerata, 359.
Dinosauria, 333, 335, 336, 338.
Dinotherium, 248.
Diplarthra, 342, 343, 346, 347.
Diploglossus monotropis, 84.
Dipnoi, 184, 324.
Diptera, 316.

Direction of repetition, on the, 192.
Doctrine of the unspecialized, the, 398.
Dohrn, 316, 317.
D'Orbigny, 101.
Dorypterus, 327.

Dualism, 421,

Dubois-Raymond, Prof. E,, 409.
Dumeril, 88, 89, 91, 95.
Dyer, 213.
Dysodus, 349.

Edentata, 342, 343, 344, 349.

Effect of impacts and strains on the feet

of mammalia, on the, xii, 373.
Effort, 195, 206-7, 426.
Elaps, 4.

Elasmobranchii, 319, 320, 324.
Electric energy, 435.
Elements of mind, the, 443.
Elephas, 377.

africanus, 110.

antiqxius, 110.

meridionalis, 110.

planifrons, 110.

primigenius, 110.
Embolomeri, 331, 332.
Embryology, 383.
Emotions, 158, 163, 381, 447.
Empidonax, 4.

" Encyclopaedia of Dentistry," 104.
Endlich, 286.
Entocondm mirabilis, 401.
" Entwickelungsgeschichte der Natter,"

94.
Eobasileus, 250.
Epochal relations, 112.
Epilasmia, 330.
Equidae, 411.
Equus, 276, 348.
Eryops megacephalus, 304.
Esequibo Indian women, 286.
Eucnemis hicolor, 114.
Eurypharyngida% 328, 329.
Eurytherium, 370.
Eutaenia, 4.

Evidence from archaeology, 150.
Evidences of derivation, 130, 215.
Evidence for evolution in the history of

extinct mammalia, xii, 294.
Evolution and its consequences, ix, 1.
Evolution of organisms, the, 422.
Evolution of the vertcbrata, progressive
and retrogressive, xiii, 314.

462

INDEX.

Evolutionary significance of human char-
acter, xii, 378.

Exact parallelism, vi, 46, 76, 139.

Extent of parallelism, 74.

Extinction of evil, the, 169.

" Extinct Mammalia of Dakota and Ne-
braska," 384.

Falco, 4,

Falconer, 55, 109.

Feelings, the, 447.

Felidfe, 349, 363, 366.

Felis, 363.

" Final Reports of the U. S. Geological

Surveys," v.
Flower, W. H., 104.

Ganocephala, 332.

Garman, 325.

Gastrsea theory, 219.

Gaudry, A., 275.

Gecconidge, 336.

Gegenbaur, 322.

General evolution, 1.

" Geological Survey of Montana," 258,

267.
Geothlypis teplirocotis, 85.
Gill, T., 329.
Goethe, 7.
Goniatites, 18.
Grade characteristics, viii.
Grade influence, viii, 203-6.
Gratiolet, 104.
Gray, 86, 176.
Gray, Asa, 208.
Greatest resistance, 30.
Gronias nigrilahris, 84.
Growth-force, 18, 190, 396.
GUnther, 58, 86, 340.
Gymnophiona, 331.
Glyptostrobus europcciis, 86.

Haeckel, ix, x, xiii, 75, 125, 190, 219

229, 415.
Halohates amcricanus, 90.
Haplodont type, 243.
Hartshorne, Prof., 397.
Hayden, F. V., v, 246, 269, 369-71, 376.

Hemibranchi, 328.

Henry, Prof. Joseph, 19, 191.

HesperornithidaB, 340.

Hetcrodon nasicus, 212.

Heterology, 96.

Heterosomata, 328.

Hippocampidae, 328.

Hippodonts, 249.

Hippopotamus, 272.

Hippotherium, 202, 411.

JIippothe7'ium gracile, 275.

History of creation, xiii.

Hogg, 89.

Holoccphali, 324.

Holothurida, 193, 399.

Hominidae, 180.

Homo sapiens, 272, 279.

Homologies and origin of the types of

molar teeth of the mammalia educa-

bilia, 241.
Homologous groups, vi, 26, 95.
Homology, 6.
Humboldt, 425.
Hume, 455.

Huxley, 15, 136, 146, 265.
Hyaenidae, 246, 349.
Hyaenodon, 366.
Hycenodon horridus, 364.
Hyaenodontidae, 246.
Hyatt, A., 2, 8, 11, oi, 91, 125, 408-9,

424.
Hyla, 4.

Hylorana erythrcna, 114.
Hyopomata, 318,324.
Hypothesis of evolution, physical and

metaphysical, vii, xii, 128, 167, 287.
Hypothesis of use and effort, the, 403.
Hypsilepis analostanus, 213.
Hymenoptera, 316.
Hyrachyus, 247.

Hyracoidea, 342, 343, 344, 346, 347.
Hyracodonts, 249.
Hyracotherium, 301.
Hyracotherium vcniicohon, 271.
Hyrax, 233.

Ichthyopterygia, 184, 333, 336.
Ichthyornithidae, 340.

INDEX.

4G3

Ichthyosaurus, 184, 336.

Icichthys, 331.

Icosteus, 331.

Improvement in architecture, 151.

Improvement in the use of materials, 150.

Increase of growth-force, 200-1.

Indo-European, 2SS.

Induction, 6, 14.

Inexact parallelism, 52, 139.

Influence of physical causes, 196.

Insectivora, 347.

Intelligence, 449.

Intelligent selection, viii, ix, 35, 208.

Isospondyli, 327.

Jena, 8.

John Day river epoch, 366,
Jones, Rupert, 86,
Jordan, D. S., 326.

Kant, 307, 449.
Kiowa Indian, 288.
Kner, R., 113.
Kolliker, 15, 103.
Kowalevsky, x, 318.

Laccrtilia, 334, 335, 336.

Lamarck, viii, 124, 342, 422, 405, 422-

423.
Lambdoiherium popoafficum, 275.
Lartet, 104, 254.
Lankester, 96, 322, 333, 337,
Laws -of evolution, the, 225.
Least resistance, 30.
Leconte, 115.
Leibnitz, 415.

Leidy, 50, 85, 258, 364, 371, 376.
Lepidoptera, 316.
Leporidse, 375.

Leptocardii, 317, 318, 319, 320.
Lereboullet, 8, 60, 74, 75, 77, 124,
Lespes, 57.
Lewes, G. H., 415.
Line of the Batrachia, the, 331.
Line of the Pisces, the, 324.
Location of growth-force, on the, 24,

195, 205.
Locke, 438.

Loew, 0., 430.
Lombard, 418.
Lophiodon, 247.
Lophodont type, 243.
Loss of growth-force, 201.
Loup Fork fauna, 302.
Loxolophodonts, 248, 250, 259.
Luchatze negro woman, 287.
Lund, 367.
Lvcodon, 4.

Mammalia^ 278.

Mammalia educabilia, ix, 241.

Mammalian line, the, 341.

Man, development of, 123, 146, 155, 267,
278.

3f uncus macrolipis, 84.

Mandibular teeth, the, 245, 249.

Manner of evolution, the, 6, 11.

Marsh, 0. C, x, 258, 277, 308, 333, 340.

Marsipobranchii, 316, 317, 318, 319,
320.

Marsupialia, 341-344, 317-348, 359.

Mastodon ohioticus, 56.

Maternal impressions, viii, 213.

Maxillary teeth, the, 244, 246,

McCook, Dr., 385.

Meehan, T., 160, 161.

Mechanical evolution, 350.

Meleagris, 24.

" Memoirs Boston Society Natural His-
tory," 51.

3fcnodus, 272.

" Mental Physiology," 438.

Mcsodon albolabris, 178.

Mesonyx, 246, 278.

Metachrosis, 211.

Metaesthetism, 421.

Metaphysical evolution, ix, 148, 378.

Metaphysical species, on. 111.

Metaphysics of evolution, 229.

Method of creation of organic types, vii,
11, 173, 229, 241, 353.

Mimetic analogy, viii, 104, 212.

Mind, development of, 214, 385, 445.

Minot, C. S., 287.

Mioclacnus corruffatiis, 275,

Mivart, 15, 28.

4:64:

INDEX.

Modifications of animals under domesti-
cation, 110.
Monas, 27.
Mongolian, 288.
Monism, 421.

Monodelphia, 344, 347, 348.
Monotremata, 341, 346, 347.
Morals of evolution, the, 236, 311.
Morris, C, 385.
Miiller, 8, 325.
Murphy, 194.
MustelidaB, 246.
Mutilla, 212.
Mycelium, 30.
Myiodioctes canadensis^ 85.

Naja, 4.

Natural selection, 2, 14, 43, 78, 106, 107,

174, 175.
Nature of actions, the, 439.
Nautilus, 18.
Necturus, 333.
Necturus maculatuii^ 49.
Negro, 288.
Neurism, 20, 205.
Numida, 24.
Neuroptera, 316.
Newton, 14.
Nimravus gomphodus^ 375,

(Estridae, 316.

Office of consciousness, 412.

Oken, 7.

Omnivora, 371.

Oncocephalus griscus, 90.

Ophiholus, 299.
triangulus^ 197.

Opbidia, 334, 335.

Oporornis agilis, 85.
formosus, 85.

Orconeetes pcUucidus, 1 3 .

Origin of automatic movements, the, 393.

Origin of consciousness, 402.

" Origin of the Fittest," xiii, 175, 225.

Origin of the foot-structure of the un-
gulates, xi, 368.

"Origin of Genera," vi, vii, 11, 41, 125,
256.

Origin of inexact parallelism, 92.

Origin of intelligence, 31.

Origin of the modern types of bunodont

and lophodont dentition, 251.
Origin of motives, 450.
Origin of the specialized teeth of the

carnivora, xi, 363.
Origin of species, 2, 7, 42, 107.
Origin of the will, x, 437.
Ornithorhynchus, 184.
Ornithosauria, 335, 336.
Orthagoriscidse, 330.
Orthoceras, 18.
Osborn, H., 277.
Ossemens fossiles, 49, 176,
Osteocephalus, 46, 221.
Ostraciontidas, 330.
Owen, Sir K., 88, 91, lOS, 318.
Oxyaena, 246, 360.
Oxycena lupina^ 365.

morsitans, 375.
Oxyrrhopus, 4.

Packard, A. S., 2, 13.

Palaeosyops, 247.

Palaeotheriodont, 258.

Palaeotherium, 247, 248.

Paleontological bulletins, xii.

Paleontological evidence, 383.

Palingenesis, 126.

Pangesthetism, 419.

Pantolambda, 360.

Pantolambda hathmodon^ 275.

Parallelism, 7.

Parallelism in higher groups, 58.

Parker, 86.

Pasteur, 431.

Pavo, 24.

Pelycodus, 360.

Perca, 4.

Percomorphi, 328, 331.

Perigenesis, ix.

Periptychus, 359.

Periptychus rhahdodon, 268, 308.

Pcrissodactyla, 250, 265, 3^'8, 371-373,

375, 399.
Permian fauna, 302.
Peters, 336.

INDEX.

465

Pharyngognathi, 330, 331.

Phenacodus, 301.

Phenacodus primoevus, 270, 273, 275, 300,

808.
vortmani, 345.
"Philosophie Zoologique," viii, 423.
Phrenism, 205.
Physical evolution, 128.
Physical origin of man, the, 146.
Physiophilosophs, 7.
Physoclysti, 328.
Physostomi, 328.
Pityophis sayi, 197.
Plagiaulax, 348.
Platypodidse, 346.
Plecostomus, 4.
Plectognathi, 330.
Plesiosaurus, 26, 188.
Pleuronectidse, 196.
Pliauchenia, 223.
Poebrotherium, 223.
Poebrotherium labiatum, 271, 370.

vilsoni, 371, 376.
Polycystina, 27.
Polyphyletic descent, vii.
Porter, Noah, xi.
Pressure, effect of, 228.
"Primitive Types of Mammalia Educa-

bilia," 246.
*' Principles of Biology," ix, xi, 423.
" Principles of Psychology," ix.
Procelurus julieni, 366.
Probable cases of transition, 83.
Proboscidia, 233, 265, 342-4, 346-8, 375,

401.
Procamehis occidentalis, 308, 376.
Procyonidee, 359.
Prostemma gutiula^ 89.
Protamoeba, 190.
Proteida, 331-3.
Proteles, 349.
Protobathybius, 420.
Protohippus sejundtis, 271, 370.
Protolabis, 223.
Protozoa, 33, 420.
Ptychodont type, 243.
Ptychostomus, 4.
Ptychosiomus pidiensis, 213.
80

Puerco fauna, 302.
Pygopodidae, 337.
Pythonomorpha, 26, 334.

Quadrumana, 179, 278, 280, 342-4, 347,
385, 899, 400, 401.

Radcliffe, 20.
Ptadiata, 27.
Rana, 4.
Rana affilis, 222.

affijiis, 47, 84.

areolata^ 48.

catcsheiana, 48.

clamata, 222.

corrugata, 48.

cyanopldydisy 48.

delalandii, 47.

ehrenhergii, 48.

fasdata, 47.

fuscigultty 48.

gracilis^ 48.

grayi, 47.

grunniens, 48.

hexadactyla, 48, 222.

mascariensis, 47.

occipitalis, 48.

oxyrhyncJms, 47, 222.

palmipes, 47.

porosissima, 47.

temporaria, 84.

tigrina, 48.

vittigera, 48.
Raniformia, 217.
Ranula chrysoprasina, 222.
Rathke, 57, 61, 76, 93.
Rationale of moral development, 166.
Rattle of the rattlesnake, the, 197.
Raymond, Dubois, 21, 409, 415.
Relation of animal motion to animal evo-
lution, xi, 266, 350.
Rationale of the development of intelli-
gence, 154.
Relation of man to the tertiary mamma-
lia, X, 268.
Relations of nearly allied genera, on

the, 44.
Relations of physical and moral nature,
158.

466

INDEX.

Eelations of the types of dentition to

types of foot, 260.
Repetitive addition, 180.
"Report on Geological Survey of Mon-
tana, Wyoming, etc.," 246.
" Report United States Exploring Survey

W. lOOth Meridian," 224.
Reptilian line, the, 333,
Respiratory and circulatory system of

vertebrates. 196.
Retardation, vi, 13, 142, 182, 281, 385.
Retardation and acceleration, 11, 43, 15,

115, 226.
Retrograde metamorphosis of energy,

427.
" Review of Birds of North America," 55.
Review of modern doctrine of evolution,

xi, 215.
Rhachitomi, 331, 332.
Rhinocerus, 247.
Rhynchocephalia, 334, 336.
Riickhard, Rabl, 319.
Roccus lineatus, 213.
Rodentia, 180, 342-4, 346, 375,
Rotifera, 315.
Ruminantia, 223, 247, 375.
Ryder, J. A., ix, 368, 409, 423.

Sacculina, 401.
Salamandra atra, 87.

maculosa, 87.
Salmo, 4.
Salticus, 212.
Saturniidae, 316.
Sauropterygia, 334, 336.
ScaridsD, 331. .
Schlosser, 370.
Schopenhauer, 453.
Schopfungsgeschichte, xiii.
Schreiber, 87.
Scincidae, 337.
Sclater and Salvin, 118.
Scolecophidia, 340.
Scombridge, 331.
Scops asio, 4.
Seeley, H. G., 335, 340.
Segment-repetition, 182.
fSelenodonts, 247.

Serranidae, 331.

Siluridae, 327.

Simia satyrus, 283.

Simiidae, 180.

Siredon, 333.

Sirenia, 342, 347, 349.

Smilodoti neogceus, 367.

Smith, Aubrey, 86.

Smyth, Brough, 291.

Spelerpes, 4.

Spencer, Herbert, viii, ix, xi, 2, 15, 413,

444, 445, 448.
Spinoza, 90, 456.

Spiritual or moral development, 157.
Spizclla pusilla, 16.

socialis, 16.
Stegocephali, 331, 332.
Stegophilus, 327.
Steindachner, 86.
St.-Hilaire, 91, 146.
Streptostylica, 334.
Structural evidence of evolution, the,

241.
Stypolophus, 246.

whitice, 360.
Subordinate types of bunodonts, the,

244.
Subordinate types of lophodonts, the,

246.
Successional relation, 7.
Survival of the fittest, 15.
Swainson, 96.

Symborodonts, 248, 250, 257.
Synopsis of the vertebrata of the eocene

of New Mexico, 245.
Synthesis of repetition, 187.

Taenia, 184.
Taeniodonta, 343, 349.
Tachyglossidae, 346.
Talpa, 360.
Tapirodonts, 247, 255.
Tapirus, 247.
Taxeopoda, 342, 347.
Taxodium distichum, 86.
TeidaD, 337.
Teleology, 7, 16.
Teleostomi, 318, 324-326,

INDEX.

467

"Tertiary Planorbis of Steiuhcira,"

408.
Testudinata, 334.
Testudinidae, 33Y.
Theory of evolution, x, 124.
Theromorpha, 333, 335, 3oY.
Thomson, Sir William, 431, 442.
Thulie, 288.
Tillodonta, 343.
Tillotherium, 248.
Topinard, 290.
Tortricidae, 340.
Trachystomata, 331, 332, 333.
Trematoda, 401.
Trichechodonts, 248, 255.
Trichodiscus, 27.
Triodopsis tridentata^ 178.
Tritubercular type of molar teeth in the

mammalia, xii, 359.
Tropidonotits sipedon^ 197.
Tryon, G. W., 177.

Types of mammalian molars, the, 241.
Typhlichthys subfei'raneiis, 1 3.
Typhlogeophis, 340.

Uhler, P. Ft., 90.
Uintatherium, 248, 274, 278.
Uintai/ierium cornuium, 277.

mirabile, 277, 308.
Unconscious, the, 391.
Unconscious cerebration, 32.
Ungulata, 347, 359, 365, 369, 374.
Unity in variety, 7.
Urochorda, 322, 323.

Urodela, 331, 332.

Use and effort, ix, 6, 194.

Vegetable growth, force of, 31.

Velia, 90.

Venus of the Capitol, 292.

Vermes, 399.

Vertcbrata, 352, 356.

Vertebrate line, the, 318.

Vibrio, 188, 192.

Viverridae, 245.

Vogt, C, 12, 401, 402.

Von Baer, vi, 8, 46, 60, 62, 74, 77, 92.

Von Siebold, 86.

Wagler, 88, 95.

Walker prize, viii.

Wallace, 13, 14, 15, 106, 174, 405.

Wallace and Bates, 212.

Ward, Lester, 430.

Wasatch fauna, 302.

Wheeler, G. M., v, 224, 317, 359, 365-

369, 375, 376.
Westwood, 89.
Whiteavcs, 323.
White river fauna, 301, 302.
Wiegmann, 95, 100.
Will, 208, 210, 434, 456.
Willis, Dr., 438.
Wrestler, the, 289.
Wortman, J. L., 104, 275.
Wyman, 87.

"*
" Zoologie Philosophique," 342, 423.

THE END.

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his work is to be attributed to the fact that he is himself an accomplished artist as
well as an authoritative expounder of science." — Ediahurgh Review^ October^ 1870,
in an article on '-'•The Fkilosophij of Color J'''

Education as a Science.

By Alexander Bain, LL. D. 12mo. Cloth, Sl.YS.

" This work must be pronounced the most remarkable discussion of educational
problems which has been published in our day. We do not hesitate to bespeak for
it the widest circulation and the most earnest attention. It should be in the hands
of every school-teacher and friend of education throughout the land." — IS'ew York

Sun.

A History of the Growth of the Steam-Engine.

By Robert H. Thurston, A. M., C. E., Professor of Mechanical Engineering
in the Stevens Institute of Technology, Hoboken, N. J., etc. With one
hundred and sixty-three Illustrations, including fifteen Portraits. 12mo.
Cloth, $2.50.

" Professor Thurston almost exhausts his subject; details of mechanism arc fol-
lowed by interesting biographies of the more important inventors. If, as is con-
tended, the steam-engine is the most important physical agent in civilizing the
world, its history is a'desideratum, and the readers of the present work will agree
that it could have a no more amusing and intelligent historian than our author." —
Boston Gazette.

Studies in Spectrum Analysis.

By J. Norman Lockyer, F. R. S., Corespondent of the Institute of France,
etc. With sixty Illustrations. 12mo. Cloth, $2.50.

" The study of spectrum analysis is one fraught with a peculiar fascination, and
some of the author's experiments'are exceedingly picturesque in their results. They
are so lucidly described, too, that the reader^ keeps on, from page to page, never
flagging in interest in the matter before him, nor putting down the book until the
last page is reached." — JS^eio York Evening Express.

New York: D. APPLETON & CO., 1, 3, & 5 Bond Street.

SCIENTIFIC PUBLICATIONS.

General Physiology of Muscles and Nerves.

By Dr. I. Rosenthal, Professor of Physiology at the University of Erlan-
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" The attempt at a connected account of the general physiology of muscles and
nerves is, as far as I know, the first of its kind. The general data for this branch of
science have been gamed only within the past thii'ty years." — Extract from Preface.

Sight :

An Exposition of the Principles of Monocular and Binocular Vision. By
Joseph Le Conte, LL. D., author of "Elements of Geology"; "Religion
and Science" ; and Professor of Geology and Natural History in the Uni-
versity of California. With numerous Illustrations. 12mo. Cloth, $1.50.

"It is pleasant to find an American book which can rank with the very best of
foreign works on this subject. Professor Le Conte has long been known as an origi-
nal investigator in this department ; all that he gives us is treated with a master-
haad." — The JVation.

Animal Life,

As affected by the Natural Conditions of Existence. By Karl Semper,
Professor of the University of Wurzburg. With two Maps and one hundred
and six Woodcuts, and Index. 12mo. Cloth, $2.00.

" This is in many respects one of the most interesting contributions to zoological
literature which has appeared for some time." — Mature.

The Atomic Theory.

By Ad. Wurtz, Membre de I'lnstitut; Doyen Honoraire de la Faculte de
Medecine ; Professeur a la Faculte des Sciences de Paris. Translated by E.
Cleminshaw, M. a., F. C. S., F. I. C, Assistant Master at Sherborne School.
12mo. Cloth, $1.50.

" There was need for a book like this, which discusses the atomic theorv both
in its historic evolution and in its present form. And perhaps no man of this age
could have been selected so able to perform the task in a masterly way as the illus-
trious French chemist, Adolph Wurtz. It is impossible to convey to the reader, in
a notice like this, any adequate idea of the scope, lucid instructiveness, and scien-
tific interest of Professor Wurtz's book. The modem problems of chemistry, which
are common!}^ so obscure from imperfect exposition, are here made wonderfully clear
and attractive." — The Fojoular Science Monthly.

The Crayfish.

An Introduction to the Study of Zoology. By Professor T. H. IIuxley,
F. R. S. With eighty-two Illustrations. "l2mo. Cloth, $1.75.

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himself the statements which they contain, will find himself brought face to face
with all the great zoological questions which excite so lively an interest at the pres-
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SUICIDE :

AN ESSAY IN COMPARATIVE MORAL STATISTICS. By Henry Morselli,
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"Suicide" is a scientific inquiry, on the basis of the Btatistical melhod, into the laws
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VOLCANOES :

WHAT THEY ARE AND WHAT THEY TEACH. By J. W. Judd, Profc?sor
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a presentation of the terrestrial facta and laws with which volcanic phenomena are asso-
ciated."—Pop?<tor Science Monthly.

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THE SUN.

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ments are plain, direct, clear, and condensed, thouch ample enough for his purpose, and
the substance of what is generally wanted will be found accurately given in jjis pages." —
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ILLUSIONS :

A PSYCHOLOGICAL STUDY. By James Sully, author of " Sensation and
Intuition," etc. 12mo, cloth. $1.50.

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The Brain and its Functions.

By J. LuYS, Physician to the Hospice de la Salpetriere. With Illustra-
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many functional observations of various other physiolog-ists, including of course Professor
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"■Dr. Luys, at the head of the great French Insane Asylum, is one of the most eminenit
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tions of the brain. We have been fascinated by this volume more than by any other treatise
we have yet seen on the machinery of sensibility and thought ; and we have been instructed
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The Concepts and Theories of Modem Physica

By J. B. Stallo. 12mo. Cloth, ll.TS.

"^ Judge Stallo's work is an inquiry into the validity of those mechanical conceptions
of the universe which are now held as fundamental in physical science. He takes up the
l.^ading modern doctrines which are based upon this rueebanical conception, such as the
atomic constitution of matter, the kinetic theory of gases, the conservation of energy, the
nebilar hypothesis, and other views, to find how much stands upon solid empirical trround,
and how much rests upon metaphysical speculation. Since the appearance of Dr. Draper's
*• Religion and Science," no book has been published in the country calculated to make so
deep an impression on thoughtful and educated readers as this volume. . . . The range
and minuteness of the author's learning, the a<nteness of his reasoning, and the sineulai
precision and clearness of his style, ara qualities which very seldom have been jointly
exhibited in a scientifi.c treatise. "■ — Xem York Sun.

The Formation of Vegetable Mould,

THROUGH Tim ACTIOX OF WORMS, WITH OBSERTATIONS ON
THEIR HABITS. By Charles Daewix, LL. D., F. R. S., author of " On

the Origin of Spedss^" etc., etc With Illustratiori&. 12mOy elotk Price,

$1.5a.

"Mr. Darwin''s Tittle volume on the- habits jmd fnstfncts erf earth-worms is no less
marked than the earlier or more elaborate etForts of his genius by freshness of observation,,
unfailing power of interpreting and correlating fact*, and logical vigoF in generalizing
upon the?m. The main purpose erf" the work is to point out the share which worms have
taken in the formation of the layerof vegetable mould which covers the whole surface of
the land in every- modei-ately humid country. All lovers of nature will unite in thanking
Mr. Darwin for the new and interesting Ireht he has thrown upon a subject so long over-
looked, yet so fun of interest and instruction, as the stnrcttrre and the labors of the earth-
worm."— Satmiim/ Eeviem.

" Respecting worms as among the most useful portions of anima'te nature, Dr. Darwim
relates, fn this remarkable book, their structure and hrsbits, the part they have played in
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rocks, the preparation of soil for the growth ol plants, and in the natural history of the
viQria.''— Boston Advertiser.

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Ants, Bees, and Wasps.

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tion, and the Primitive Condition of Slan," etc., etc. With Colored Plates.
12mo, cloth, $2.00.

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in^r the last ten years, with a view to test their mental condition and j)Owei-s of sense. The prin-
cipal point in which ?ir John's mode of experiment dift'ers from thost.- of lluber. P^ord. McCook,
and others, is that he has carefully watched and marked particular insects, and has had their
nests under observation for Ions' periods — one of his ants' nests havinj,' been imder c<mstatit in-
spection ever since 1S74. His observations are made principally uj)on ants because they show
more power and flexibihty of mind; and the value of his studies is that they belong to the de-
partment of original research."

" We have no hesitation in saying that the author has presented \is with the most valuahie
series of observations on a special subject that has ever been produced, charuiingly written, full of
logical deductions, and, when we consider his multitudinous engagements, a remarkable illus-
tration of economy of time. As a contribution to insect psychology, it will be long before this
boot finds a parallel." — London Athenceum.

Diseases of Memory :

An Essay in the Positive Psychology. By Tii. Ribot, author of " Heredity,"

etc. Translated from the French by William IIlntingtox Smith. 12mo,

cloth, $1.50.

"M. Eibot reduces diseases of memory to law, and his treatise is of extraordinary interest.*'
—Philadelphia Press.

"Not merely to scientific, but to all thinking men, this volume will prove intensely interc:£t-
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"M. Ribot has bestowed the most painstaking attention upon bis theme, and numerous ex-
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Philadelpkia North American.

'•To th« general reader the work is made entertaining by many illustratiors connected with
6uch namt'j as Linnaeus, Newton, Sir Walter Scott, Horace Vernet, Gustave Dore, and many
others."— larrishurg Telegraph.

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" It is not too much to say that in no single work have so many curious cases been brouglit
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Myth and Science.

By Tito Yignoli. 12mo, cloth, price, $1.50.

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quered myth is extremely well wrought out, and is probably in essentials correct." — Saturduy
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" An attempt made. Avith much ability and no small measure of success, to trace the origin and
development of the myth. The author has pursued his inquiry with much patience and ingenuity,
and has produced a very readable and luminous treatise.''' —p'hiladelphia JVorth Ainerican.

" It 13 a curious if not startling contribution both to psychology and to the em-ly history ol
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N'ew York : D. APPLETOX & CO., 1, 3, «fe 5 Bond Street.

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Man before Metals.

By N. Jolt, Professor at the Science Faculty of Toulouse ; Correspondent
of the Institute. With 148 Illustrations. 12mo. Cloth, $1.75.

" The discussion of man's origin and early history, by Professor De Quatrefages, formed one
of the most useful volumes in the ' International Scfentific Series,' and the same collection
is now further enriched by a popular treatise on paleontology, by M. N. Joly, Professor in the
University of Toulouse. The title of the book, ' Man before Metals,' indicates the limitations of
the writer's theme. His object is to bring together the numerous proofs, collected by modern
research, of the sreat age of the human race, and to show us what man was. in respect of cus-
toms, Industries, and moral or religious ideas, before the use of metals was known to him.'' —
New York Sun.

"■ An interesting, not to say fascinating volume." — New YorJc Churchman.

" M. Joly's book sums up the discoveries of modern science bearing on the primeval history
of man, on the antiquity of the human race, and on the circumstances attending its slow and
partial ascent to the modern level of civilization. It also presents with brevity but thoroughness
the generally accepted theories relating to the habits and environment of primitive man. Its
usefulness and interest are much increased by numerous and excellent illustrations." — Pkiladel-
phia North Amencan.

" This is a book worth owning." — New Toric Christian Advocate.

Animal Intalligence.

By George J. Romanes, F. R. S., Zoological Secretary of the Liunsean
Society, etc. 12mo. Cloth, %l.1o.

" My object in the work a3 a whole is twofold : First, I have thought it desirable that there
should be something resembling a text-book of the focts of Comparative Psychology, to which
men of science, and also metaphysicians, may turn whenever they have occasion to acquaint
themselves with the particular level of intelligence to which this or that species of animal
attains. My second and much more important object is that of considering the facts of animal
Intelligence in their relation to the theory of descent." — From the Preface.

" Unless we are greatly mistaken, Mr. Eomanes's work will take its place as one of the most
attractive volumes of the ' International Scientific Series.' Some persons may, indeed, be dis-
l)osed to say that it is too attractive, that it feeds the popular taste for the curious and marvelous
without supplying any commensurate discipline in exact scientific reflection : but the author has,
we think, fully justified himself in his modest preface. The resnlt is the appearance of a collec-
tion of facts which will be a real boon to the student of Comparative Psychology, for this is the
first attempt to present systematically well-assured observations on the'mental life of animals.
—Saturday Revieiv.

"The author believes himself, not without ample cause, to have completely bridged the sup-
posed gap between instinct and reason by the authentic proofs here marshaled of remarkable
Intelligence in some of the higher animals. It is the seemingly conclusive evidence of reasoning
powers furnished by the adaptation of means to ends in cases which can not be explained on the
theory of inherited aptitude or habit."' — 2\ew York Sun.

The Science of Politics.

By Sheldon Amos, M. A., author of " The Science of Law," etc. 12mo.
Cloth, ll.YS.

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the modern schools in the English field, not slighting the teachings of the American Eevolution
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New York : D. APPLETON & CO., 1, 3, & 5 Bond StreeL

D. APPLETON & CO.'S PUBLICATIONS.

CHAPTERS IN POI.ITICAL ECONOMY. By Albert S. Bolles,

Lecturer on rolitical Economy in the Boston University. Square 12ttio.

Cloth, 11.50.

CONTENTS.— The Field and Importance of Political Economy : The Payment of
Labor; On the Increase of Wages; Etiect of Machinery on Labor ; On the Meaning and
Causes of Value ; A Measure of Value ; Money and its Uses : Decline in the Value of Gold
and Silver; The Money of the Future; The Good and Evil of Banking; The Financial
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Interference with the Loan of Money, Payment of Labor, and Contracts of Corporations ;
Advantages of Exchange ; Taxation.

FINANCIAL HISTORY OF THE UNITED STATES FR03I

1774 TO 1789, EMBRACING THE rEKIOD OF THE AMERICAN

REVOLUTION. By Albert S. Bolles. 8vo. Cloth, S2.50.

" It fills a place and meets a want which, so far as my observation extends, is not pup-
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FINANCIAL HISTORY OF THE UNITED STATES FROM

1789 TO 18G0. By Albert S. Bolles. 8vo. Cloth, $3.50.

FINANCIAL HISTORY OF THE UNITED STATES FR03I

1861 TO 1885. By Albert S. Bolles. 8vo. Cloth, $3.50.

NOMISMA ; OR, " LEGAL TENDER." By Henri Cernuschi, author of " Bi-
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The principal part of the information contained in this volume was given by the author,
before a commission appointed by Congress, for the purpose of ascertaining whether it
was feasible for the United States to introduce a bi-metallic standard of gold and silver.

The author is an authority on tinance in France.

ON THE PROBABLE FALL IN THE VALUE OF GOLD. By

Michel Chevalier. Translated by Richard Cobden. Svo, Cloth, §1.25.

WEIGHTS, MEASURES, AND MONEY OF ALL NATIONS.

Compiled by F. W. Clarke, S. B., Professor of Physics and Chemistry in the
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HAND-BOOK OF SOCIAL ECONOMY; OR, THE WORKER'S A

B C. By Edmond About. 12mo. Cloth, $2.00.

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POLITICAL ECONOMY. By W. Stanley Jetons, Professor of Logic and
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PRINCIPLES OF POLITICAL ECONOMY, WITH SOME OF
THEIR APPLICATIONS TO SOCIAL PHILOSOPHY. By

John Stuart Mill. 2 vols. 8vo. Cloth, $4.00 ; half calf, extra, $8.00.

In the whole range of extant authorship on political economy, there is no writer except
Aflam Smith with whom John Stuart Mill can, without injustice, be compared, in
originality, Adam Smith, as being the acknowledged father of the science, takes the pre-
cedence, as he does also in exuberance of apt illustration. But in rectitude of understand-
ing, clearness, and sagacity, Mill is fully his peer; in precision of method, range of topics,
and adaptation to the present state of society, he is altogether his superior. The '•'Wealth
of Nations " now belongs, indeed, rather to the history of the science than to its exposi-
tion. But the "Principles of Political Economy" is'an orderly, symmetrical, and lucid,
exposition of the science in its present advanced state. In extent oi" information, breadth
of treatment, pertinence of fresh illustration, and accommodation to the present wants of
the statesman, the merchant, and the social philosopher, this work is unrivaled. It is
written in a luminous and smooth, yet clear-cut style; and there is diffused over it a soft
atmosphere of feeling, derived from the author's unaffected humanity and enlightened in-
terest in the welfare of the masses.

MILL^S PRINCIPLES OF POLITICAL ECONOMY : ACniDGED,
WITH CRITICAL, BIBLIOGRAPHICAL, AND EXPLAXATORY XOTES,
AXD A SKETCH OF THE HISTORY OF POLITICAL ECONOMY. By
J. Laurence Laughlix, Ph. D., Assistant Professor of Political Economy in
Harvard University. With Twenty-four Maps and Charts. A Text-Book for
Colleges. 8vo. 658 pages. Cloth, $3.50.

"An experience of five years with Mr. Mill's treatise in the class-room convinced me,
not only of the great usefulness of what still remains one of the most lucid and systematic
books yet published which cover the whole range of the study, but I have also been con-
vinced of the need of such additions as should give the results of later thinking, without
militating against the general tenor of Mr. Mill's system ; of such illustrations as should
fit it better for American students, by turning their attention to the application of princi-
ples in the facts around us ; of a bibliography which should make it easier to get at the
writers of other schools who offer opposing views on controrerted questions : and of some
attempts to lighten those parts of his work in which Mr. Mill frightened away the reader
by an appearance of too great abstractness, aud to render them, if possible, rnore easy of
comprehension to the student who first appioacbes Political Economy through this
author.-'— i^^AOWi Preface.

THE STUDY OF POLITICAL EC0IV03IY. HIXTS TO STU-
DEXTS AXD TEACHERS. By J. LaurExVce Laughlin, Ph. D., Assistant
Professor of Political Economy in Harvard University. 16mo. Cloth, $1.00.

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ures into a general form, in order that they might assist inquirers in any part of the
country."— i^rcwi Preface.

THE HISTORY OF BIMETALLIS3I IN THE UNITED STATES.

By J. Laurence Laughlix, Ph. D., Assistant Professor of Political Economy
in Harvard University. 12mo. Cloth.

MONEY. By Charles Moran. 12mo. Cloth, $1.25.

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THE MAN VERSUS THE STATE: containing " The New Toryism,*^
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cal Superstition," liy Herbert Spencer. With a Postscript. Small 8vo.
Paper, 30 cents.

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of Mr. Spencer. Men of all parties should read his earnest warniniis a^jainst the periloue
drift of that spirit of interference and meddlinjr with private concerns of which every
year we see many evidences at Washington and all the State capitals."— iN'ei^; York Jour-
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DYNAMIC SOCIOLOGY, or Applied Social Science, as based upon
Statical Sociology and the Less Complex Sciences. By Lester F.
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fully vindicates from the oppi-obrium with which superficial prejudice has surrounded
them, and we would particularly recommend to all those who take interest in social ques-
tions, and who are capable of free and unbiased thought, his remarks upon 3Iarriage In-
stitutions.

" We are glad to find that Mr. Ward strongly dissents from the views expressed with
such curious emphaj^is by Mr. Herbert Spencer upon the subject of compulsory state educa-
tion. A consideration of the matter, means, and method of education brings to its con-
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expounded, can not fail to derive benefit, more especially if they are capable of brintring to
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CONFLICT IN NATURE AND LIFE: A Study op Antagonism in
the Constitution op Things. For the Elucidation of the Problem of Good
and Evil, and the Keconciliation of Optimism and Pessimism. 12mo, cloth,

$2.00.

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