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BOOKS BY
WILLIAM EMERSON RITTER

The Higher Usefulness of Science.

The Probable Infinity of Nature
AND Life.

The Unity of the Organism, or
the Organismal Conception of
Life. Illustrated.

The Unity of the Organic Species,
with Special Reference to the
Human Species.

War, Science and Civilization.

An Organismal Conception of
Consciousness,

RICHARD G. BADGER, publisher, BOSTON

r

THE UNITY OF THE
ORGANISM

OR
THE ORGANISMAL CONCEPTION OF LIFE

BY

William Emerson Ritter

Director of the Scripps Institution for

Biological Research of the University

of California, La Jolla

California

TWO VOLUMES
VOLUME ONE

ILLUSTRATED

BOSTON

RICHARD G. BADGER

THE GORHAM PRESS

Copyright, Idli), by Richard G. Badger

All Rights Reserved

This work contains the text of the hook:
**An Organismal Theory of Consciousness" •

Made in the United States of America

The Gorham Press, Boston, U. S. A.

TO MY WIFE

MARY BENNETT RITTER

MY SEVEREST CRITIC AND
BEST HELPER

PREFACE

'THHE right of any book to live must be determined finally
-*■ by what is on its pages. Nevertheless, when the author
of a scientific book undertakes such a task as I have under-
taken in this one, his natural and acquired fitness for carry-
ing out his project ought to count in some measure toward
the determination. An attempt to speak with some degree
of originality and autliority on subjects so remote from one
another as are the chemistry of organisms, heredity, human
consciousness, and the nature of knowledge, would be some-
what audacious even if made by an author of secure reputa-
tion as an investigator in one or more of these fields. When,
however, the attempt is that of a complete stranger to all
the fields, as thus judged, the attempt is no longer entitled
to be called "somewhat audacious." It is audacious out and
out, and if defensible at all is defensible in spite of its
audacity. But the very nature of the task I have attempted
seems to require me to contend that while it is audacious it
is yet not impossible, and to point out something of my own
qualifications for performing it.

Such professional fitness as I have rests primarily on my
being a general zoologist in the proper sense ; that is, a
student of the phenomena of the animal world without ex-
clusion of any aspect of that world from professional in-
terest and some measure of professional attention. These
facts of my vocation, and of my conception of the nature of
that vocation are crucial for the quality not only of this
book but all my general writings.

If once one becomes as deeply convinced as I am of both
the fundamental unity and the fundamental diversity of all

ix

X Preface

nature; if, in other words, he becomes convinced that the
whole of nature is, indeed, and not in mere expression, a
system, the conviction will carry with it the perception that
all specialized natural knowledge is absolutely dependent for
meaning on the relation it has to its appropriate larger body
of knowledge. Either analytic knowledge or synthetic knowl-
edge of nature would be wholly void of meaning were it to
be completely wrenched from the other. Most men of
science perhaps, and most philosophers probably, would ad-
mit that this is true as an abstract proposition. But what
about its truth when brought to the test of particular cases?

The audacity of my enterprise really consists in my at-
tempting to act according to this general truth in a par-
ticular case — the case, that is, of the phenomena of animal
life. I have gone on the assumption that knowledge of
animal chemistry, for example, at one extreme, and of
human consciousness at the other, would be simple blanks as
to meaning but for the relation of the two knowledges to
each other and to still more general knowledge of animal
life. Could we imagine a chimpanzee possessed of as much
laboratory knowledge of organic chemistry as an Emil
Fischer, that knowledge would be really meaningless were
the creature's mind that of a chimpanzee in all other re-
spects.

A systematic defense of a conception of zoology based on
a general theory of natural knowledge such as this, can not,
of course, be thought of in a preface. Indeed, such a con-
ception can not be fully justified by any argument merely
for it. The justification must be found largely in a worked-
out application of the conception itself. In other words, the
very fabric of this book must be the chief justification
sought. All I can wish to do in a preface is to mention
certain subsidiary ideas and principles that have been spe-
cially influential in determining the plans of my undertaking;
and certain methods and disciplinary preparations and pres-

Preface xi

ent conditions that have been specially useful in carrying
them out.

Probably no one zoological item has influenced me more
than the perception that the evolutionary interpretation of
man does not mean that man's derivation from the lower
animals made him something that is now not animal. It
means that man is just as much an animal to-day as were
his prehuman ancestors. The truth is exactly stated by
saying that when the transformation took place by which
man came into existence that transformation was from a
lower to a higher stage of animal life. The actual problem,
consequently, of man's nature is not as to what man is in
opposition to animals, but as to the kind, or species of ani-
mal he is.

With the distinction here made once fully grasped comes
the revelation tliat man is an object of zoological research
and treatment no less certainly than is a horse, a fish, a
lobster, or an amoeba. But since man's highest, that is his
psychical or spiritual attributes are the ones most decisive
of his hvnd, it is these attributes which make him particularly
interesting, zoologically speaking — just as, for example, it
is the attributes of a horse as a horse, and not as an animal
generally that elicits our particular interest in the horse.
Zoology rightly understood is preeminent among all the
sciences as the science of particulars. This important truth
seems to have been first appreciated by Aristotle; and the
fact that one of the most fundamental differences between
him and his teacher, Plato, concerned the doctrine of Par-
ticulars as opposed to that of Universals, is probably con-
nected closely with Aristotle's great interest in and attention
to zoology. I have not seen any reference to this surmise
by writers on Aristotle and his philosophy, yet it appears
to me highly significant.

From these perceptions relative to the nature of man and
the science of animal life, it follows that when the zoological

xii Preface

study of man is undertaken — when the general zoologist
becomes for the time being an anthropological zoologist —
all the best tested and most approved methods of that
science are taxed to their uttermost, simply because of the
great complexity of the species under examination. Now it
is absolutely beyond question, I believe, that of the methods
employed in the biological sciences, none are more important,
especially for the study of man, than those of description
and classification with their necessary accompaniment, com-
parison. The essay The Place of Description, Depnition a7ul
Classification in Philosophical Biology in my little book. The
Higher Usefulness of Science, treats of this subject some-
what at length. But that to which I attach mucli more
importance is that almost everything contained in the pres-
ent book, except the heart of Chapter 24, I regard as an
embodiment of the fundamental principles of descriptive and
classificatory biology as these principles are established by
modern research.

It seems to me I am privileged to claim that no reader of
this and other general writings of mine is in position to pass
judgment on them, except, of course, as touching trustworthi-
ness of observation and statement, and of dependability of
authorities cited, without having considered conscientiously
my position as to method. For instance, am I right or wrong
in holding (see the above mentioned essay) that far the
larger part of what is usually called explanation in dealing
with the phenomena of nature is really partial or tentative
or hypothetical description and classification .^^ What justi-
fication and scope are there for my contention that the motto
"neglect nothing," which has long done good service in taxo-
nomic research based on morphology, must be extended to
all departments of structural and functional biology.'^ What
grounding and applicability are there for my distinction
between synoi)tic and analytic description, and synoptic and
analytic classification? Not until one has come to see that

Preface xiii

questions of this sort arc necessary consequences of progress
in information about, and interpretation of living nature,
is he able to appreciate fully what I mean by chemical and
psychological zoology. Formal biochemistry and animal
psychology, that is, the chemistry and the psychology of
laboratories devoted to these subjects, are to my zoological
eyes really quite Incidental and partial and crude, albeit
immensely important. Let one once feel the full weight of
the inductive evidence favorable to the hypothesis that every
organism whatever performs every jot and tittle of its ac-
tivities through chemico-physical agencies, and he must at
tlie same time feel the meagerness and crudity, compara-
tively speaking, of even the fullest and best laboratory
knowledge of those agencies by which he himself, let us say,
operates as he carries through and expresses in words an
argument like that now occupying us.

The absolute trustworthiness of the main findings of
laboratory biochemistry and its incalculably great impor-
tance, but at the same time its great imperfection as com-
pared with natural biochemistry, are what especially impress
me as I bring my best powers to bear on the deepest, most
distinctive problems of anthropological zoology ; problems,
in other words, of tlie human animal.

Sucli an attitude toward biochemistry will, I hope, be
recognized even by biochemists as calculated to induce at
least a receptive frame of mind toward knowledge in this
domain. It should be one Important qualification for "read-
ing up" In the domain. But certain it is that something
more than a receptive mind is essential to enable one disci-
plined in one field of science to be a successful gleaner of
ripened fruit in another field. It Is not true that all the
domains of natural knowledge, highly developed as they now
are, are enough alike to make training In any one an ade-
quate preparation for acquiring second hand knowledge in
every other. At least a background of systematic instruc-

XIV Preface

tion in a particular science is requisite to make a liiglilj
successful reader even in that science.

So far, then, as I am able to pass upon my own quali-
fication for making such use as I have made of biochemistry,
it is a question of whether I have a sufficient ground-work
of formal training to make me a safe chooser among authori-
ties and estimater of the significance of their results.

Although my chemical practice was limited to three years,
one of these as a student assistant, so much did I live in the
laboratories during that period, that even to-day the open-
ing of a book or journal on chemistry seems to fill my nose
with foul though pleasantly reminiscent odors and to en-
crust and stain my fingers with diverse corrosives — all of
which may mean that I was more a musser in chemicals than
a real student of chemistry. Nevertheless I verily believe
the experience enabled me to be a more intelligent reader of
chemical writings.

As for the science of mind, I am obliged to own that I
have never spent a day in an experimental laboratory of
either animal behavior or human psychology. But I own
also that for this I am not regretful if such defect of train-
ing be an essential condition of escape from the narrowing
of interest in and conception of "behavior" which has at-
tended later work in this field. I do not believe, however, that
this is the only way of such escape. Zoologists must realize
before long, I am quite sure, that laboratory experimentation
in animal behavior can be only a rather minor agent for the
task of understanding the psychical life of the animal world
as a whole.

This leads to the remark I wish to make about the discus-
sion of psychic integration in the last chapters of this book.
One of the most important things accomplished by that dis-
cussion is, I estimate, the calling attention to the tendency
of instinctive activity to excessiveness over the actual needs
served by the activity. Why has this truth (for there can

Preface xv

be no question that it is a truth) not received more atten-
tion from modern beliavior specialists? There are probably
several reasons, but a particularly influential one seems to be
the fact that the very purpose, and the method of experimen-
tation involving the idea of control by the student are
such as to encourage overlooking the phenomena, and to
obscure their significance even if they are noticed.

Unorthodoxly enough from the standpoint of present
school psychology, my entrance into this realm was from
the side of the nature and the theory of knowledge. And so
far as my explorations in the realm have gone, two men,
Aristotle and the late Professor G. H. Howison have influ-
enced me so vitally that I must say a few words on the
subject.

For many years Aristotle was two distinct persons to me,
so far as any real influence upon my thinking was con-
cerned. On the one hand there was Aristotle the metaphysi-
cian to whom I had been formally introduced by Howison in
a private outside-of-hours University course (which with
great generosity he had given me), the medium of the in-
troduction being the De Anvma. On the other hand was
Aristotle the zoologist, acquaintance with whom was at first
picked up in the usual naturalist fashion, but which had
later ripened into intimac}^, as I like to characterize it, by
our common interest in marine zoology, his good description
of the anatomy of a tunicate being a special passport to my
affection. It would hardly be an exaggeration to say that
all my philosophizing in biology has aimed at fusing these
two Aristotles into one. I do not mean that this has been
my conscious and express aim. It has been so only instinc-
tively, or intuitively, or "at heart," or by "working hy-
pothesis," or by whatever expression one chooses for it.
And here comes the part played by Professor Howison : As
I take a bird's eye view now of what is set forth in this and
other general writings of mine, and contemplate the whole in

xvi Preface

the light of the preface to Howison's book, The Limits of
Evolution, and then look reflectively back over my thirty
years of contact with him and his teachings, most of it inci-
dental and fitful, but some of it rather close, a few influences
of his, sonie positive and some negative, stand out sharply
indeed. The positive influences I mention first. No other
influence contributed so much to my belief in the power of
reason ; that is, in a substratum of truth to the idealistic
philosophy. Again no other influence contributed more to
my belief in persons — in the power of personality; that is,
in a substratum of truth to the Howisonian philosophy of
personal idealism.

A statement of the negative influence coming from the
same source takes us back to Aristotle. In the preface to
The Limits of Evolution Howison writes, referring to his
own theory of Personal Idealism, "The character of the
present theory, relatively to Aristotle, is to be found in its
attempt to carry out the individualistic tendencies in Arls-
totelianism to a conclusion consistently coherent." This
statement I could almost adopt word for word as a charac-
terization of the purpose that has animated all my general
thinking and writing. Yet how profoundly does the out-
come of my eff*orts diff^er from that resulting from Profes-
sor Howison's efforts ! And here is the kernel of my present
remarks : In commending to me the De Anima of Aristotle
and generously undertaking to guide me through it, as a
response to my appeal for help toward clarifying my mind
concerning the deeper, the philosophical meaning of bio-
logical evolution, my greatly learned and much esteemed
teacher had a purpose, I am now quite sure, that is impos-
sible of realization. That purpose was to show that Aris-
totle failed in his eff'ort to recognize a "real world" through
combining "ideal form" w^ith "real matter," because for him
a real world was more fundamentally a sense-experienceable
world than is actually the case. As I labored through the

Preface xvii

De Anima I recall that I was disturbed by the rather cavalier
fashion in which we disposed of those portions of the work
which treat of reproduction, nutrition and growth, and espe-
cially the portions dealing with the senses. At the stage
of scientific development I was then in, I knew little or noth-
ing of Aristotle's biological writings, and Howison referred
to them only in the most cursory way, if indeed he men-
tioned them at all. Certain it is he did nothing to arouse
my interest in them, or to indicate that he regarded them
as specially significant in connection with such important
views of Aristotle's as those on the relation of Body and
Soul. The question which now seems to me indispensable
for grasping the essense of the Aristotelian psychology and
philosophy that, namely, of why Aristotle was so greatly in-
terested in zoology, and devoted so much time to its study,
never came up during the course, I am quite sure. In sci-
ence and philosophy as in everything else, the character of
one's interests is a surer index to his general views and atti-
tude than is anything he can express verbally. There may
be ambiguity and error in Aristotle's theory of "synthetic
Entelechy." This theory may, probably does, "beset," as
Howison remarks, "all individual existence both behind and
before," thereby implying some theoretical derogation from
the real nature of personality. But over against this error
and ambiguity stands indubitable proof of Aristotle's prac-
tical faith in the Particular, the Individual, that proof be-
ing the vast labor he expended in learning and interpreting
the life of the animal world. The chief philosophic signifi-
cance of Aristotle's zoological works is not in any informa-
tion or theories they contain but in the fact that he pro-
duced them at all, since, as mentioned above, zoology is pre-
eminent as the science of particulars, and his doctrine of
Particulars as opposed to Universals was very close to the
heart of his whole philosophic system.

This prepares for my final remark about the influence upon

xviii Preface

my thinking of Professor Howison and the idealistic philoso-
phy generally. That philosophic Idealism, no matter of
what variety, contains elements that are fundamentally er-
roneous seems to me to be proved more conclusively by its
inadequacy for understanding the world in its entirety than
by any particular errors of fact or reasoning which it can
be shown to contain. Were all men philosophical idealists,
there would be no natural science, merely because in the
domain of learning men will not choose as their primary
life work what they fully believe to be of secondary im-
portance.

Fallaciousness or inconclusiveness of argument never de-
terred me half as much from embracing Professor Howison's
teachings in their entirety as did his usually dignified but
always-present presumption of professional self-superiority
over all his colleagues who did not come under the, to him,
sacred segis of Philosophy. The reason why sincere humility
and the spirit of democracy are alien to all forms of idealis-
tic philosophy becomes clear once one attains a world view
which truly strives to include, but makes no pretense of hav-
ing already included, the whole world wholly in that view.

There remains the pleasant though difficult task of men-
tioning the few among my numberless obligations which are
so personal and weighty that to leave them unacknowledged
would be to brand me as ungrateful, more conspicuously than
I can endure.

First as to those persons and conditions which, during the
last ten years, have relieved me from the routine duties of a
University teacher, and also from most of the exactions
customarily attaching to an administrative post even in an
institution of scientific research, and have given me a status
the central purpose of which is scientific work. Whatever
be the quality and final significance of my life-work, could
these, I ask myself, have reached as high a level as they
have reached had I not come into my present position? Al-

Preface xix

most certainly not, must be the answer. And beyond a doubt
the raising of the question involves principles of organization
for scientific research that lift it high above mere personal
concern.

No faith of mine is greater because none is rooted more
deeply in my scientific philosophy, than that in the ultimate
triumph of popular, that is of democratic principles in all
aspects of civilization. Indeed the facts — not the theories —
of organic unity and integration which have dominated all
my later work are the foundation of this faith. Whether
my particular hypotheses and theories of organismalism suc-
ceed or fail, there still are the raw data on which they rest.
These can not fail. If success does not crown my efforts in
handling the data it will crown those of others who shall
come after me. And when the principles for which I contend
shall have worked themselves more fully into the fabric of
civilization, the organizational, the administrative, and the
scientific policies aimed at in the Scripps Institution for Bio-
logical Research of the University of California will be
recognized as fundamentally sound. I will be specific here
to the extent of mentioning the policy of providing a special
business management for such institutions.

Although my indebtedness to my professional co-workers
and official associates of the Zoological Department and the
]\Iuseum of Vertebrate Zoology at Berkeley, Professors C. A.
Kofoid, S. J. Holmes, and Dr. Joseph Grinnell, is indicated
by special references in the body of this book, I should be
sorry to have these references taken to indicate the full ex-
tent of my obligation to them, or to indicate that these are
the only members of those departments to whom I am in-
debted.

It would be a source of keen regret to me, too, should my
single short reference to two of my biological associates on
the staff of the Scripps Institution, Mr. E. L. Michael and
Dr. C, O. Esterly, be taken a-s the full measure of what I

XX Preface

owe to them. I hope that my reference to their work, brief
though it is, will be recognized as indicative of the high im-
portance I attach to what they have done and are doing.

But what about my indebtedness to professional associates
here in the home group of whose work no mention is made
in my text? How subtle and far-reaching and innumerable
are the influences which bear upon one from his daily co-
workers ! For example, by what unit of measurement could
be gauged the effects on my treatment of heredity, which have
come from my perpetual contact with the work of Dr. F. B.
Sumner and Mr. H. H. Collins ? But these men would prob-
ably resent the ascription to them of responsibility for my
main conclusions in this field. Again, not many "environ-
mental factors" have been more determinative of my present
feelings (I hardly dare call them views) relative to various
problems in geo-physics, and relative to quantitative meth-
ods in natural science, than have Dr. G. F. McEwen and his
oceanographic work. Yet I hesitate even to mention this
fact lest some one be led thereby to hold Dr. McEwen ac-
countable for crudities, actual or implied, I may manifest
in these domains.

Nor are my indebtednesses confined to the narrow circle
of my immediately professional and official co-workers. In-
deed I am keenly conscious of great debts beyond this circle.
These are so numerous and on the whole so general as to
make specification impossible, but I cannot pass by without
mentioning my debt to my long-time and much-cherished
friend. Professor G. M. Stratton, for the connnentaries on
the chapters on psychic integration made by him while this
portion of the book was in an advanced though still forma-
tive stage.

For aid in structurel labor, as it may be called, my de-
pendence upon Mr. Frank E. A. Thone, my secretary and
scientific assistant, has been varied and intimate, and of a
quality for which money can only partly pay.

Preface xxl

To Dr. Christine Essenberg, librarian and member of the
scientific staff of the Scripps Institution, I am indebted for
help on the index and glossary.

And finally, what can I say about the part played in the
creation of this and my other works by her to whom this
volume is dedicated? The extent to which her life is involved
with mine in these works only we two can know ; but the
wording of my dedication indicates something of the char-
acter of that involvement.

CONTENTS

PART I

CRITIQUE OF THE ELEMEXTALIST COXC'EPTION OF THE

ORGANISM

A. Composition of the Living Individual

CHAPTER PAGE

I. IxTROnUCTORY 1

Historic background, 1. Nature and scope of the undertak-
ing, 24.

II. The Orgaxism axd its Major Parts 30

Reflections on the problem of individuality in the living world,
30. The individual plant and its parts, 33. The individual
animal and its parts, 39.

III. The Aximal Organism axd its Germ Layers .... 45
The germ-layers, their role in development, and the germ-layer
theory, /^o. Are germ-layers developmental organs and subser-
vient to the developmental requirements of the organism? ^<5.

A negative answer to the question in the last section expected
of elementalist biology, 49. Evidence that germ-layers are
thus subservient to the organism, 49: (a) Evidence from bud
propagation in compound ascidians, 50; (6) Evidence from
bud propagation in bryozoa, 53; (c) Evidence from the regen-
eration of the lens of the amphibian eye, 57. The germ-layer
theory and the germ-plasni theory, 58. The exact mode of
involvement of the germ-plasm theory in the germ-layer
theory, 59. Weismann's studies on the origin of germ-cells in
hydroids, 60. Inconclusiveness of Weismann's results shoion
by Goette and others, 62. Weismann's erroneous conclusions
concerning the origin of sex-cells in hydroids as an example
of the effect on the observing powers of the germ-plasm type
of speculation, 66. The strongly organismal implications of
Goette's conclusions on the origin and migration of germ cells

xxiii

xxlv Contents

CHAPTER PAGE

in hydroids, 68. Remarks on the relation of germ-cells to
germ-layers and to the organism generally, 72, The relation of
ideas and observations as exemplified in the discussions of this
chapter, 74'

IV. The Organism and its Chemistry 75

Standpoint of the discussion that of the evolutionary natural-
ist, 75. The organism as a chemical laboratory, 78. Different
organisms as different chemical laboratories, 83. (a) Different
odors and flavors of animals cmd plants as distinguishable by
man, 84- {b) Differences in animal odors as distinguished by
animals themselves, 88. The ruituralist's approach to biochem-
ical problerns, 90. Some biochemical results viewed from the
naturalist's standpoint, 95. (a) Reichert and Brown's results

on hcemoglobin, 95; {b) The precipitin reaction between bloods
of different ani/mals, 99; (c) Comparative chemistry of the
sperm, of different species of fishes, 102; {d) Comparative
chemistry of milk of different species, 103; (e) Comparative
chemistry of digestive enzymes, 104; (/) Instances in general
biochemistry where interesting facts of comparative chemistry
are incidentally brought out, 106. The coalescence of natural
history and comparative biochemistry, 107. Provisional enur-
m,eration of chemico-naturalist inquiries, 109. Peculiar im-
portance to natural history of the application of physical
chemistry to the chemistry of living beings, 110: (a) Iridi-
viduation and speciation of "organic matter" ftinda/mental
biologic facts. 111; (6) Indications that variation and indi-
viduation are primarily chemical, while constancy and uni-
formity are primarily physical, 115.

V. The Organism and its Protoplasm 130

Protoplasm and mystification, 120. Responsibility for the
mystification of protoplasm, 121. Conception of animal sar-
code and plant protoplasm, as "identical stuffs," 123. Max
Schultze's actual teachings as to protoplasm and sarcode, 125:
(a) Cell nucleus distinct from protoplasm, but both nucleus
and protoplasm essential to life of cell, 126; (6) Recognized
common attributes but not identity of protoplasm in all or-
ganisms, 128. Ernst Briicke's conception of the cell as an
organism, 129. Characteiistic organization in all cells, 131.
Results of later descri/ption and classification of cell sub-

Contents xxv

CHAPTER PAGE

stances, 133: (a) Cyfojjlasni and karyoplasni cliff ereiitiated
areas of a common ba.sic substance, 135; (b) Details of cyto-
plasmic structure, 137; (c) lliree mxiin theories of the struc-
ture of 'protoplasm,, 138; (d) "No universal formula for proto-
plasmic structure," 139. Preliminary remarks on the bearing
of physical chemistry on the protojjlasm doctrine, I40. Ex-
perimental evidence for the specificity of protoplasms, 1/^3:
(a) Greater fusibility between closely related species as in
tissue mixtures and grafts, lJf3; (b) Protoplasms and not
protojylasm must be the form of the protoplasmic conception,
148.

VI. The Organism and its Cei,t.s 150

What the cell-theory is, viewed historically and substantively,
150: (a) Importance and general character of the theory,
150; (b) Various forms of the theory as currently held, 150;

(c) Statement of the theory justified by present state of
knowledge, 154- Certain inadequacies of the cell-theory, 158:
(a) As tested by embryonic development, 158; (b) As tested
by isolated cells and tissues, 167.

VII. The Cell-theory not Sufficient for Explaining the Or-

GANIS3I 179

More general inadeqiuicy of the cell-theory, 179: (a) As
tested by the regeneration and restitution of mutilated organ-
isms, 179; (b) As tested by the principle of aggregation, 182.
(c) As tested by the specificity and metaplasy of differen-
tiated cells, 186. Summary of examination of inadequacy of
cell-theory, 190. Advance t&ivard the organismal standpoint
through conception of cell reached by biochemistry p^ursued in
accordance loith the principles of physical chemistry, 191.

VIII. Further Exa3iination of the Cell-Theory . . . 198
The mosaic theory, 198. What the mosaic theory is, 198; A
modicum of truth in the mosaic theory, 198. The theory of
totipotence, 202. Experimental facts on ichich the theory
rests, 202. Balancing the account between the mosaic and
totipotence theories, 206. The "promorphology" of germ cells,
211: (a) Facts of immediate observation on which the coTir-
ception rests, 212; (6) Grounds for believing minute observ-
able specific differences between germ cells important, 214;

xxvi Contents

CHAPTER PAGE

(c) Re/lections on a 'promorpliology of germ cells beyond the
Umits of lusibility.

IX. Organisms Consisting of One Cell 237

A. Adult form and structure. Remarks on the conception

of the cell as an elementary organism, 221. Com,parison of
the structure of a single cell with that of orgatiisms composed
of many cells, 230: (a) Comparison of certain ciliates and
metazoans, 232; (6) Comparison of a radiokirian and a jelly-
fish, 235; (c) Comparison of the shell of a rhizopod and a
nautilus, 237. The unjustifiable conception that unicellular
organisms can have no tissues, 240. True organs in some pro-
tozoans, 242. A true nervous system probably present in some
protozoa, 244- -^ more critical examination of the term "or-
gan," 245. More detailed examination of the anatomy of
higher protozoa, 249. The fiction of structureless organisms,
256. The structure of bacteria, 257 : (a) Membrane and sur-
face structures, 257; (6) Structure of inner portion, 260; (c)
The question of a nucleus in bacteria, 261. Bacteria un-
doubted organisms whether ''true cells" or not, 263. B. De-
velopment, 267. False conceptions about development in pro-
tozoa, 267. Misuse of the term "ontogeny," 271. Development
of Stentor as an example of protozoan ontogeny, 272. The
terms ''embryology" and "ontogeny" inevitably used by in-
vestigators of protozoan reproduction, 277.

X. History of the Attempt to Subordinate the Protista to the

Cell-theory . . . 280

Clash between Ehrenberg and Dujardin a special case of the
conflict between organismal and elementalist conceptions, 280.
Modern opposition to the effort to Tnake protista conform to
celhdar elementalism, 286: (a) Position of Friederich Stein,
286; (b) Position of Huxley, R. Hertwig and others, 288.
General conclusions from examination of knowledge and views
as to the nature of uni- and multicellular organisms, 291.

B. The Production of Individuals by Other Individuals

XI. The Nature of Heredity and the Problem of its Mechan-
ism

Heredity the chief present-day stronghold of biological ele-

305

Contents xxvii

CHAPTER PAGE

mentalism, 305. This due particularly to discovery of inter-
dependence between adult characters and chromosomes of
germ-cells, 306. Revised conception of heredity essential to
interpreting this interdependence, 307. Unwarrantal>le tend-
ency to restrict heredity to sexual propagation, 308. Unwar-
rantable tendency to restrict heredity to adult characters, 311.
Importance of recognizing heredity as working by transforma-
tion rather than by transmission, 312. Tendency to confuse
heredity tvith causes of heredity, 313. Definition of heredity
adopted in this discussion, with remarks on its application to
the chromosome theory, Sl/f. Meaning and criterion of "mech-
anism of heredity," 322.

33fi

XII. EviDEXCE Favorable to Chromatin as Hereditary Sub-

STAXCE ..........

A. Direct Evidence. Evidence from the ontogeny of some
protozoans, 3S6. Evidence from certain cells of multicellular
organisms, 331. Evidence from spermatozoan, 333. Evidence
from pigment cells, 333. B. Indirect Evidence, 341. The
chromosomes of germ-cells in fertilization, 342. Fertilization
of the ova of one species by the sperm of another species, 344'
The connection of sex with a particular chromosome, 346. The
connection of mutations with particular chromosomes, S53.
Chromosomes and the Mendelian mode of inheritance, 356.

XIII, Kvidexce from Protozoans That Substances Other Than

Chromatin Are Physical Bases of Heredity . . . 369
Evidence from the ontogeny of various protozoans, 363: (a)
Stentor, 363; (b) What study of the ontogeny of Diplodinium
will probably discover, 370; (c) The origin of flagella, 370;
(d) Various organs of Stylonychia and Paramecium, 373; (e)
The skeleton of radiolaria, 375; (f) Openings in the central
capsule of the radiolaria, 379; (g) The shells of foraminifera,
385; (h) The clinging organs of sporozoa, 386; (i) The "di-
vision center" of Noctiluca, 390; (j) The centrosphere of pro-
tozoa generally, 394. Concluding remark on the evidence pre-
sented, 397.

LIST OF ILLUSTRATIONS

FIGURE PAGE

1. Diplodinium (After Sharp) 231

2. Hydra (After Parker and Parker) 232

3. Stylonychia Mytilus (From Hartog, After Lang) . . .233

4. Stenostoma Leucops (After Ott) 233

5. Stylonychia Mytihis (After Putter) 235

(>. Stylonychia Histrio (After Maier) 250

7. Crithidia Leptocoridis (After McCuUoch) 251

8. Crithidia Leptocoridis (After McCuUoch) 252

9. Giardia Muris (After Kofoid and Christiansen) . . . 255

10. Coryceila Armata (From Wasielewski, After Leger) . . 270

11, 12, 13, 14. Stentor Caeruleus (After Johnson) . . . 274, 275

15. Frontonia Leucas (After Tonniges) 327

l(j. Naegleria Gruberi (After Kofoid) 329

17. Spermatid of the Rat (After Duesberg) . . . . .334

18. Spermatid of Salamander (After Heidenhain) . . . .334

19. Spermatid of Snail (After Heidenhain) 336

20. Flagelliim of Euglena (After Biitschli) 371

21. Frontonia Leucas, Trichocyst (After Tonniges) . . . 374

22. Aulosphaera (After Haecker) 376

23. Aulosphaera Elegantissima (After Haecker). Detail of

Structure 377

24. Auloceros (After Haecker). Detail Section of Spine . . 377

25. Aulacantha (After Borget) 379

26. Acanthometron Pellucidum (After Moroflf and Stiasny) . . 381

27. Euglypha Alveolata, Division Stages (After Minchin) . . 384

28. Development of Pyxinia (After Leger and Dubosq) . . 387

29. Epimerite of Pileocephalus Heerii (After Lankester) . . 388

30. Epimerite of Geneiorhynchus Monnieri (After Lankester) . 388

31. Epimerite of Echinomera Hispida (After Lankester) . . 388

32. Epimerite of Beloides Firmus (After Lankester) . . . 389

33. Epimerite of Comeloides Crinitus (After Lankester) . . 389

34. Noctiluca Miliaris (After Hertwig) . ... . . .390

35. Fission Stages of Noctiluca Miliaris (After Calkins) . , 39X

XX13?

V

PART I

CRITIQUE OF THE ELEMENTALIST CONCEPTION

OF THE ORGANISM

A. Composition of the Living Individual

THE UNITY OF THE ORGANISM

Chapter I
INTRODUCTORY

Historic Background

EVERY biologist is familiar with the phrase "the organ-
ism as a whole." It occurs over and over again, par-
ticularly in later 3^ears, in written and spoken discussion
touching a wide range of subjects; and the essential idea,
expressed in different tenns, is still more common. To at-
tempt an exhaustive list of instances of the use of the
phrase or its equivalents would be profitless, but enough
must be said both at the outset and at various places
along the way to furnish a secure historic foundation for
the enterprise we are undertaking.

In its earliest infancy the science of living beings pre-
sented two theories apparently diametrically and irreconcil-
ably opposed to each other. Stating the case in familiar
terminology, according to the one the organism is explained
by the substances or elements of which it is composed, while
according to the other the substances or elements are ex-
plained by the organism. * Since it will be necessary to
refer frequently throughout our discussion to these two

* The word "explain" calls so loudly to be itself "explained" when
used in this offhand way that one reluctantly lets it go unheeded even
temporarily, but it must be passed now with this sole remark: whatever
meaning may be attached to it in one of the above propositions, exactly
the same meaning must it have in the other.

1

2 The Unity of the Organism

standpoints or theories, a short designation for each is
desirable. Historically viewed they might be spoken of as
the Aristotelian and the Lucretian. But far more satisfac-
tory because descriptive in a luminous way, are the terms
"organismal theory," or if one may be permitted to coin a
word, "organismalism," for the Aristotelian ; and "elemental
theory," or "elementalism" for the Lucretian.

The essence of the idea is set forth with admirable clear-
ness in the early pages of that protogenal book on zoology,
On the Farts of Animals, by Aristotle. "But if man and
animals and their several parts are natural phenomena,
then the natural philosopher must take into consideration
not merely the ultimate substances of which they are made,
but also flesh, bone, blood, and all other homogeneous parts ;
not only these, but also the heterogeneous parts, such as
face, hand, foot, and so on. For to say what are the ulti-
mate substances out of which an animal is foraied ... is
no more sufficient than would be a similar account in the
case of a couch or the like. For we should not be con-
tent with saying that the couch was made of bronze or wood
or whatever it might be, but should try to describe its de-
sign or mode of composition in preference to the material.
. . . For a couch is such and such a form embodied in this
or that matter, or such and such a matter with this or
that form. ... It is plain, then, that the teaching of the
old physiologists is inadequate, and that the true method
is to state what are the definitive characters that distin-
guish the animal as a whole; to explain what it is, both in
substance and in form, and to deal after the same fashion
with its several organs." ^

Not only is the idea itself piquantly stated, but as no one
will fail to notice, the antithetic idea with which it has had
to contend perpetually from that day to this is also unmis-
takably indicated. Another cardinal point will not be
missed: not only does Aristotle sketch these two antithetic

Introductory 3

ideas with a firm hand, but he leaves no room for doubt as
to which side of tlie a^cs-long controversy he is on. He is
always on the side of the organism as against its substance.

Were we permitted to take this statement by Aristotle
out of its setting in his general doctrine of living beings it
would very well present, as far as it goes, the standpoint
that will be maintained in the present treatise. However,
when we come to follow him further and find what his dis-
tinction is between substance and form, and to see how
the latter is related to the soul and becomes involved in the
problems of purpose and necessity, we have to recognize that
in reality the passage comes a long way from meaning what
we should mean by the same words. Wherein the difference
lies will appear as our enterprise develops.

The earliest defender of the opposite idea whom we shall
notice was Lucretius. Although this poet-naturalist pro-
fessed to be a follower of Empedocles and Epicurus, his
formulation of biological elementalism is so explicit and so
readily accessible to modem readers that it will sei've well
the needs of this discussion. In the third, book of The
Nature of Things Lucretius gives his reasons for rejecting
the Greek notion of the "mental sense" of man and animals
as a Harmony — a something which arises as a vital product
of the whole, and then defends at length the counter hypo-
thesis, namely that the mind and soul, that is, life, is a defi-
nite, indep.endent, though complex substance. I quote a
few sentences from the theory which Lucretius is sure is
right, using the translation by the Reverend J. S. Watson :
"I shall now proceed to give you a demonstration, in plain
words, of what substance this mind is, and of what it con-
sists. In the first place, I say that it is extremely subtle,
and is formed of very minute atoms." After illustrating the
activity and pervasiveness of the soul throughout the body,
the author continues : "It must therefore necessarily be
the case, that the whole soul consists of extremely small

4 The Unity of the Organism

seminal-atoms, connected and diffused throughout the veins,
the viscera and the nerves." Then comes a discourse on the
nature of the soul substance: "Nor jet is this nature or
substance to be regarded by us as simple and uncom-
pounded. For a cert~ain subtle aura, mixed with heat, leaves
dying persons ; the heat moreover, carries air with it. . . .
Nor yet are all these constituent parts, aura, heat, and air,
sufficient to produce mental sense or power. A certain
fourth nature or substance must therefore necessarily be
added to these : this is wholly without a name ; it is a sub-
stance, however, than which nothing exists more active or
subtle, nor is anything more essentially composed of small
and smooth elementary particles ; and it is this substance
which first distributes sensible motions through the mem-
bers. . . . This fourth principle lies entirely hid, and re-
mains in secret, within ; nor is anything more deeply seated
within the body ; and it is itself, moreover, the soul of the
whole soul." ^

The further need our enterprise has to draw upon history
as such permits us to leap across nearly eighteen centuries,
for the next occurrences touching these theories which
greatly concern us belong to the period of splendid achieve-
ment in the sciences of living beings from Linnaeus' System
of Nature to Darwin's Origin of Species. The course of
thinking and discovery during this period has been so in-
terpreted as to appear to constitute a virtual proof of the
correctness of the elementalist theor3^ It is said that in the
Linnean era plants and animals were treated from the
standpoint of the organism as a whole, and that later, under
the chieftainship of Cuvier, "instead of the complete or-
ganism, the organs of which it is composed became the chief
subject of analysis." Then, w^ith Bichat leading, came tlie
advance to the tissues ; then before long the discovery w^as
made that not the tissues but the cells are the real units
of structure, Schleiden and Schwann being foremost in this

Itifroductor// 5

forward step; and finally, with tlic demonstration, ac-
complished chiefly by Max Schultze, that one substance,
protoplasm, is the common basis of life in plants and ani-
mals, real biology was attained. This interpretation de-
clares that on the morphological side there was progress
step by step "from the organism as a whole to organs, to
tissues, to cells, and finally to protoplasm, the study of
which in all its phases is the chief pursuit of biologists." ^

This picture is undoubtedly true to a certain extent.
Science surely began with observations on organisms whole
and living, and only gradually did it take them to pieces
to learn their parts and so to deepen understanding. But
in so far as it gives the impression that the study of organic
beings has moved along a direct course from the organism
as a whole toward the ultimate elements or substances of
which organisms are composed, and has become scientific
just in so far as and no further than it has advanced in
this direction, becoming genuine biology only when proto-
plasm is reached, it is not in accord with history or the
nature of scientific knowledge. The introduction of the
word biology into science by Treviranus and Lamarck in the
very first years of the nineteenth century was deliberate
and fully justified though it had no special reference to tis-
sues or cells, much less to protoplasm. But the unfaithful-
ness of the above sketch to actual history which I wish to
point out particularly, concerns the part played by the
group of French biologists of which Cuvier is the best
known member.

It would hardly be possible to miss more completely the
significance of these men than to conceive Cuvier as making
the "organs of which the organism is composed" the chief
subject of study "instead of the completed organism." The
distinctive feature about the school was not the idea of the
organs as such, but as parts of the whole. The ensemble,
the principles of co-existence, or correlation, of subordina-

6 The Unity of the Organism

tion of organs and "characters," are what stand out most
prominently in the writings of these men, so far as general
conceptions are concerned. Cuvier, as above indicated, is
regarded as the central figure of the group, but this comes
more from the vast extent of his achievements and from
his general masterfulness than from his originality and
depth of insight. The leading idea was not due to him, as
he fully recognized, but to the Jussieus, uncle and nephew.
Concerning their Geriera Plantariiim, Cuvier said in his
History of the Natural Sciences: "This work produced a
veritable revolution in botany, for only since its publication
have plants been studied according to the relations which
they exhibit and according to the totality of their organiza-
tion." These botanists, we are told, conceived the organs
and parts to be correlated with one another, i.e., dependent
on each other and united to form the totality of their or-
ganization. Cuvier made this principle his own by adoption,
and applied it with great vigor and success in all his zo-
ological and anatomical studies. His statements of it are
numerous and varied in form, one of the fullest and clearest
being in the "Discourse" with which the Researches on Fos-
sil Fishes is introduced : "Every organized being forms a
whole, a system unique and closed, of which the parts mu-
tually correspond and concur in the same definitive action
through a reciprocal reaction. No part may change with-
out the others changing also ; and consequently each of
them, taken separately, serves as an index and an exposition
of the others." ^

While Cuvier made much of this principle, his shortcom-
ings in understanding and applying it are obvious and far-
reaching. He used it primarily in the interest of classifica-
tion, and classification seems to have been the first goal of
liis scientific endeavor. But it being as little possible for a
Cuvier as for any other thoughtful biologist really to go
no further than to glean and marshall facts, it was exactly

IntrofJuctory 7

this principle that became his speculative stronghold, and
then his speculative undoing. He made it the basis of his
conception of types, and the Type became with him a sort
of Platonic Idea, an eternal, more or less subjective entity.
It was in the hands of Geoffroy Saint-Hilaire, Cuvier's
early collaborator and later antagonist, that the principle
received its best development. Working out a Theory of
Analogies in his Philosophical Anatomy, he considers sev-
eral possible explanations of analogies but rejects all but
three, these being: (1) the relative position, the mutual de-
pendence of organs; (2) the elective affinities among the
organs, defined to mean that "the materials of the organs
survive in some fashion the organs themselves, and, when
the latter cease to exist, the analogy nevertheless does not
cease"; and (3) the balance of organs, the meaning of which
is that "an org^n, normal or pathologic, never acquires an
unusual prosperity, without a related organ, or one in the
same system, suff'ering for it." ^

Saint-Hilaire's application of these principles to the in-
terpretation of rudimentary organs and to teretological
growths show well the thorough- going objectivity of his
conception ; and his Principles of Philosophical Zoology
(1830) are only accentuated examples of the fact that the
organism as a whole, as he looked upon it, was the organism
as composed of all its parts, and further, that he was a
genuine biologist if ever there was one, in spite of the fact
that if he ever saw any protoplasm there is no evidence that
it played any considerable part in his thinking. This whole
group of the late eighteenth and early nineteenth century
biologists must be taken not only as upholders of the or-
ganismal theory, but as having greatly advanced its defini-
tion and application.*

* Were it our purpose in this chapter to present an exhaustive critical
study of the presence and growth of organismal conceptions in biology
it would be necessary to examine somewhere, probably at this point, the
ideas of the oryanicists, a group of embryologists and physiologists who

8 The Unity of the Organism

As we glanced at the organismal and elemental theories
when they opposed each other in the infancy of biology, we
must look at them still opposing each other in this era of
what we may call the adolescence of the science. The or-
ganismal side we have already spoken of in our glance at
the work of the French biologists of the early nineteenth
century. As an elementalist of this period I choose Theodor
Schwann. In his Microscopical Researches into the Accord-
ance in the Structure and the Growth of Aiiimcds and
Plants, published in 1839, he said: "We may, then, form
the two following ideas of the cause of organic phenomena,
such as growth, etc. First, that the cause resides in the
totality of the organism. By the combination of the mole-
cules into a synthetic whole, such as the organism is in every
stage of its development, a power is engendered, which en-
ables such an organism to take up fresh material from
without, and appropriate it either to the formation of new
elementary parts, or to the growth of those already present.
Here therefore the cause of the growth of the elementary
parts resides in the totality of the organism.

"The other mode of explanation is that growth does not
ensue from a power resident in the entire organism, but
that each separate elementary part is possessed of an inde-
pendent power, an independent life, so to speak: in other
words, the molecules in each separate elementary part are
so combined as to set free a power by which it is capable
of attracting new molecules and thus increasing, and the
whole organism subsists only by means of the reciprocal
action of the single elementary parts. So that here the sin-
worked during the first two-thirds of the nineteenth century. Delage
(L'Heredite, p. 750) mentions C. E. Von Baer, Claude Bernard, M.
l?iohtit, W. His and K. Pfliiger as representative of this group. The
philoso])hic'al importance of the ideas held by these investigators has been
emphasized by I.. J. Henderson (The Order of Nature). But there is,
as I believe, a vein of subjeotivistic metaphysics implicit in their con-
ceptions which throws them somewhat out of the main organismal
current.

Introductory 9

gle elementary parts only exert an active influence on nu-
trition, and the totality of the organism may indeed be a
condition, but is not in this view a cause." ^

It is hardly necessary to say that Schwann himself
adopted the view last presented, and that cells were, as he
believed, the "elementary parts" mentioned in his statement.
Under other heads we shall find it necessary to speak with
some fullness of Schwann's doctrinal views and mode of
reasoning. Our needs in this purely historical reference
will be satisfied by calling attention to the fact that he
states the elementalist theory in general terms only, that is,
in terms of "elementary parts" and "molecules." This fact
shows his conception of the problem in the large. His con-
tention that cells are the elements sought must be under-
stood to be an hypothesis secondary only to his broader
conceptions. The recognition of this two-fold aspect of
Schwann's teaching I deem of prime importance, for it shows
clearly that his theory of cells as the ultimate elements of
living beings was not a conclusion arrived at by purely in-
ductive processes, but rather as an interpretation of cells
in accordance with an ancient idea well known to him and
adopted by him. So the very great significance of Schwann's
work must be looked upon in two distinct lights : first, in
that of a generalization of unqualified validity and of the
highest importance, concerning the proximate composition
of plants and animals, that is, their cellular composition ;
and second, in that of furnishing what seemed so solid a
foundation for the ages-old elementalist theory of living
beings as to secure to it well-nigh complete domination of
biological thought for a generation. I think it is not going
too far to say that through the influence of the cell theory
as promulgated by Schwann, following as it did close upon
the foundation of histology by Bichat, the organismal con-
ception lay almost wholly dormant during the fifty years
from 1840 to 1890.

10 TJie Unity of the Organism

This reference to Schwann as an elementalist being
primarily in the interest of our historic background, a crit-
ical examination of his position would be out of place. But
it is desirable to call attention to one important logical, or
perhaps more properly psychological, implication of his
standpoint. The elemental theory applied to organisms
w^hich, as we have just seen, he stated so well and adopted
in his interpretation of the cellular composition of organ-
isms, is in reality not so much of a theory of organic
phenomena themselves as of knowledge of those phenomena.
In other words, Schwann started out in his investigations
not, in the first instance, with a theory of organisms, but
with a theor}^ of knowledge of organisms. The great im-
portance of this mode of approach to biological problems
will be brought out more fully later. Enough is it to re-
mark here that so much has the theory of scientific knowl-
edge applied in Schwann's position grown in definiteness and
influence with time, that to-day many biological elementalists
hold unquestioningly the view that the sum and substance
of scientific knowledge of organic beings is a knowledge of
the elements of which these beings are composed. According
to the theory of biology held by these biologists, the busi-
ness, and the only legitimate business, of the science is to
reduce organisms to as few and as simple elements as pos-
sible ; and in its extreme form the aim is exactly what
it was with the very earliest elementalists, namely to reach
finally one or a very few ultimate elements. To explain or-
ganisms is, according to this theory of knowledge, to reduce
them to their elements, and it is nothing else.

Since 1890 the organismal view has exhibited a rather
vigorous reanimation. Details as to how this has come
about and as to what the renewed manifestations of life
consist in cannot be entered into now. Hovvx'ver, one highl}^
significant circumstance must be noted : the rehabilitation
has h^d little or nothing to do with the form assumed by

hitroduetory 11

the theory in the hands of the French biologists considered
above. It has on the contrary arisen in a sense de novOy and
in consequence of a growing recognition of the inadequacy
of elcnientalism as bodied forth in tlie cell theory applied
to the development of individual organisms. So while we
listen now to voices that have been raised against the at-
tempt to explain ontogenesis as a cellular phenomenon mere-
ly, it must be borne in mind that we are doing so not for
the purpose of examining the cell doctrine in general, but
only to fix attention on the historical fact that the elemen-
talist standpoint as manifested in this aspect of the cell
theory finds itself face to face once again with its old
opponent, the organismal standpoint. The cell theory as
such will demand a chapter for itself, when its turn comes.
The case of the organismal theory is shown with special
clearness in the writings of three American biologists, C. O.
Whitman, E. B. Wilson and F. R. Lillie. Whitman, as is
well known, was primarily an embryologist, his best re-
searches having been on the development of leeches and
bony fishes, and his observations in this field were the start-
ing point for his views on the relation existing between
cells and the organism. In his essay, The Inadequacy of the
Cell-Theory of Development, he says : "Comparative em-
bryology reminds us at every turn that the organism domi-
nates cell-fonnation, using for the same purpose one, several,
or many cells, massing its material and directing its move-
ments and shaping its organs, as if cells did not exist, or as
if they existed only in complete subordination to its will,
if I ma}^ so speak." "^ And he ends the essay The Seat of
Formative and Regenerative Energy, with this : "The fact
that physiological unity is not broken by cell-boundaries is
confirmed in so many ways that it must be accepted as one
of the fundamental truths of biology." ^ The reader should
not fail to notice that while in both these essays Whitman's
arguments were against the hegemony of cells, in the one

1^ The Unity of tJie Organism

case he was looking at the organism primarily from the
morphological standpoint while in the other he viewed it
more from the physiological side.

In the mere matter of extent and deliberateness of re-
liance-upon the principle of organic wholeness, nothing in
recent biological literature with which I am acquainted is
more impressive than what one finds in The Cell in Develop-
ment and Inheritance, by E. B. Wilson. The organism as
a whole or some obvious substitute therefor is appealed to
on no less than seventeen pages of this book, these appeals
being scattered all through from the beginning to the end
of the volume. So far as such views of this distinguished
cytologist have been embodied in a single sentence, the fol-
lowing in his essay. The Mosaic Theory of Dezrelopment
seem to contain them : "The only real unity is that of the
entire organism, and as long as its cells remain in con-
tinuity they are to be regarded, not as morphological indi-
viduals, but as specialized centers of action into which
the living body resolves itself, and by means of which the
physiological division of labor is effected." ^

The most recent and in several ways the most significant
presentation of the organismal theory in relation to cells
comes from another embryologist, F. R. Lillie. It is worth
noting that this time the chief grounds of the presentation
are experimental embryology, whereas with Whitman they
are embryology unaided by experiment. In 1906 Doctor
Lillie published an unusually interesting research on the de-
velopment of a species of worm, Chaefopterus pergamen-
taccus. The kernel of the results was a confirmation and
extension of previous observations by himself and several
other investigators that under certain conditions the embryo
of some species of annelid worms may progress some dis-
tance on the develo})inental course before cellular or even
nuclear multiplication takes place. The author's summary
of facts may be given in his own words : "In general the

Introductory 13

following statement may bo made concerning the differen-
tiation of the uninucleatcd eggs. (1) Organs are never
formed, but only such structural elements as may occur
in single cells of the trocho])hore. (^) Organs may, how-
ever, be simulated by the aggregation of the characteristic
matter of the organ, for instance in the case of the yellow
endoplasm, which simulates the gut of the trochophore, or
the row of large vacuoles situated near the upper margin
of the yellow endoplasm which simulates the row of vacuoles
of the prototroch. (3) Structural elements appear in the
same order of time as in the trochophore. (4) The distri-
bution of the structural elements tends to resemble that of
the trochophore. (5) The yellow endoplasm (yolk?) is used
up, apparently for the maintenance of the metabolism in the
ciliated unsegmented eggs precisely as in the larva." ^^ The
theoretical bearings of the observations are indicated by the
following: "The possibihty of a considerable amount of
embryonal differentiation without either nuclear or cyto-
plasmic division may be considered established. This in it-
self is an important fact, for it disposes effectually of all
theones of development that make the process of cell-division
the primary factor of embryonal differentiation, whether
in the form of Weismann's qualitative nuclear division, or
Hertwig's cellular interaction theory. Further, the phe-
nomenon establishes firmly, as I pointed out in 1901, the
view that the role of cell-division in development is prima-
rily a process of localization.^^

Lillie presents his still broader interpretation in an ex-
ceedingly interesting section headed "Properties of the
Whole (Principle of Unity)." From this I quote somewhat
more at length than is essential for our immediate purpose
of gaining a bird's-eye view of the field we are entering, since
later w^e shall want to examine several of the Items more
closely. "The traditional view, held by many embryologists
at the present day, is that the physiological unity arises in

14 The Unity of the Organism

the course of embryonic development by the secondary
adaptation of originally independent parts to one another;
But this explanation has, in my opinion, become untenable,
and must be replaced by the view that there are certain
properties of the whole, constituting a principle of unity of
organization, that are part of the original inheritance and
thus continue through the cycles of the generations,
and do not arise anew in each. Weismann places this prin-
ciple of unity of organization in the architecture of the
germ-plasm, but, as I cannot accept his view of vast com-
plexity of the germ-plasm, neither can I accept this prin-
ciple in the, sense of Weismann." ^^ . . . "If any radical
conclusion from the immense amount of investigation of the
elementary phenomena of development be justified this is:
That the cells are subordinate to the organism, which pro-
duces them, and makes them large or small, of a slow or
rapid rate of division, causes them to divide, now in this
direction, now in that, and in all respects so disposes them
that the latent being comes to full expression. . . . The
organism is primary, not secondary ; it is an individual, not
by virtue of the cooperation of countless lesser individual-
ities, but an individual that produces these lesser individu-
alities. . . . The persistence of organization is a primary
law of embryonic development." ^^

Without looking further into recent and contemporaneous
literature, enough has been brought forward to show that
the organismal standpoint has a solid footing in current
biological theory. We should, however, be grievously amiss
should we conclude that because the theory has captured
one stronghold it lias won the whole battle. As a matter
of fact, the very men who have admitted the rights of the
organism as against its cells in development are yet far
from admitting those rights as a general proposition; that
is, as against all the elements of whatever order that enter
into its makeup. Thus Whitman says, "If the formative

Introductory 15

processes cannot be referred to cell-division, to what can
tliev be referred? To cellular interaction? . . . The
answer . . . will ... as Wiesncr has so well insisted, find
a common basis for every grade of organization. It will
fin<l the secret of organization, growth, development, not in
cell-division, but in those ultimate elements of living matter
for which idiosomes seems to me an appropriate name." ^*
This sentence, w^ith those immediately following it, leaves
no question that in 1893, when he wrote the essay in which
it occurs. Whitman was at heart an elementalist as much as
was Lucretius or Schwann or Weismann. The only real
step he had taken in the direction of the organismal stand-
point was that of seeing clearly that the cells could not be
'^ultimate units" of organization. Indeed there is consider-
able indication that so far as the general problem is con-
cerned, tlie position he held in 1893 was somewhat backward
from that w^hich he held five years before, when he w^rote The
Seat of Formative and Regenerative Energy, for in that
essay he said: "Let us now consider whether any rational
basis can be found for the idea of a formative power as a
resultant from, and an expression of, physiological unity.
I am fully conscious that the subject is one of profound
mystery, the solution of which appears to lie as far beyond
our grasp to-day as at any time in the past. We draw
nearer to the problem, but the effect is rather to enhance
than to reduce its apparent magnitude. Every step in ad-
vance only brings us to a keener sense of the subtle and
incomprehensible nature of the force or forces contem-
plated." 1^

The extent and nature of Wilson's faltering between the
two standpoints, even as between the organism and its cells,
in spite of his constant and earnest appeal to the the organ-
ism as the "only real unity" we shall consider in some de-
tail when we deal with the cell-theory.

Lillie has, I believe, advanced farther toward the con-

16 The Unity of the Organism

ception that will be defended in this work than either of the
other biologists whose view we are now considering, even
though he Is far from admitting the organism to full stand-
ing in his conceptions. "Undoubtedly," he says, "it [the
principle of unity] is capable of further analysis, and it
must ultimately be derived from particular relations and
properties of material particles" ;^*' and the conceptual form
which the material particles, by virtue of their "particular
relations and properties" assumes in Lillie's mind is the
"formative stuffs" which, since the theory of such sub-
stances was first given definiteness and plausibility by Juhus
Sachs, have figured largely in speculative biology. "The
theory of formative stuffs," Lillie writes, "does away with
any 'determinant' hypothesis. 'Characters' are not due to
'unfolding' of the 'potencies' of 'detemiinants' but are re-
sults of morphogenic reactions between two or more forma-
tive stuffs. The 'character' need no more be preformed in
the reagents (formative stuffs) in the case of a morphogenic
than in the case of a chemical reaction." ^^

This interesting, and up to a certain point entirely ac-
ceptable, language of Lillie's will be examined more closely
in another connection. Enough for now to say dogmatically
that the author's "formative stuffs" is only another elemen-
talist refuge and so no more satisfactory than is the cellular
refuge which he himself abandons, or than are any of the
innumerable other refuges to which innumerable other ele-
mentalists have fled.

The historic background for our enterprise will be com-
pleted when we have pointed out how it is faring with these
two theories at present. This can be done with great brev-
ity since what we find will be exactly what will most occupy
us when we come to the substantive rather than the historic
part of our task, when the superstructure rather than the
foundation is at hand.

The organismal line of descent which our cursory sur-

Introductory 1*7

vcy has traced from tlic period of Aristotelian zoology,
through that of French comparative anatomy of the late
eighteenth and early nineteenth centuries, through what
might with propriety be called the period of American em-
bryology, now barely ended, holds its unmistakable course
on into what we may speak of as a physiological period,
in the midst of which we now are. It should be remarked
tliat "physiological" as lierc used does not refer so much
to pliysiology in the professional sense as to an approach
to certain developmental phenomena of the organism from
the functional side, since the biologists who are tending to-
ward the organism al theory are not primarily physiologists
but students of individual development.

The term most characteristic of this latest outcrop of
organ ismalism is correlation, and what is distinctive about
the present effort as contrasted with that which marked
the idea of correlation held by the French anatomists is
tliat now the correlatedness of parts in the organism is being
h)oked at from the functional more than from the structural
side ; and that the necessity is felt more than it was in the
earlier period, of finding a causal explanation of the correla-
tions. "Equilibrium" is anotlier term that is frequently
used by the biologists whose thinking is of this cast, and
the kinship of this to Saint-Hilaire's "balance" will not
escape the reader's notice. This doctrine of physiological
correlation is receiving its fullest elaboration at the hands
of C. M. Child, though numerous investigators are con-
tributing importantly to it. K. Goebel, E. Radl, W. Pfeffer,
L. Jost, J. Nusbaum, E. Schultz, H. Rand, S. J. Holmes
and C. Zeleny may be mentioned as biologists who have
dealt more or less directly with the problem. Undoubtedly
H. Driesch's "harmonious equipotential systems" ought to
be mentioned in this connection, though this author's un-
qualified commitment to an extra-natural explanation of
biological phenomena will hardly permit us to enroll him

18 The Uiiity of the Organism

in the group of workers referred to.

The organismal standpoint escapes its ancient adversa-
ries when it comes to expression as physiological correlation
just as little as it has escaped when it has appeared under
any of its earlier forms. Thus although correlation plays
a large role in the writings of W. Rbux, the founder of
developmental mechanics, approach to the correlation-com-
plex for him seems always to be from the direction of the
elements in the complex and never from that of the complex
itself ; so it results that the organism as such has no stand-
ing in his conceptions on a par with that of the elements
which constitute it. This fact comes out clearly from an
examination of the various definitions bearing on the point
given by Roux in his Terminologie der Enhdcklungsme-
chanik der Tiere und Pfianzen. Thus as a definition of or-
ganism we find '^Orgajiism means a complex of organs ; hence,
of instruments." ^^ Or for living being (regarded as a syn-
onym for organism) we find: ^^Limiig beings^ bion, pi. bion-
ten, are natural bodies which distinguish themselves
'minimally' from inorganic natural bodies through a sum
of definite elementary functions which directly or indirectly
subserve self-preservation, as also through self-regulation
in the exercise of all these functions ; and thereby, in spite
of 'self-alteration,' and through the same, and also in spite
of the necessary complicated and soft structure, are very
permanent." ^^ Again, " 'Ganzbildung,' Holoplast, is a more
or less fully developed, but fully formed structure, represent-
ing an entire organism, which has arisen out of a blastomere,
or egg-fragment." ^^

From these as typical definitions it is seen that in no case
is organism conceived and defined as having characters
wholly its own, but, by implication, only those belonging to
its parts. Indeed, a critical study of the speculative writ-
ings of Roux and his adherents will, I believe, convince any
one that tlie most characteristic thing about developmental

Introductory 19

mechanics as a system of thinking on biological subjects is
its effort to deal with organisms in terais of parts of or-
ganisms; otherwise expressed, that it is a systematic effort
to avoid recognizing the organism in itself as a true objec-
tive entity. Because of the persistence, industry, enthusiasm,
and withal great ability shown by Roux in applying ele-
mentalism to many aspects of living beings, his title to
chieftainship of what the Germans call "Zersplitterungs-
theorien" can hardly be disputed, at least so far as this
present era is concerned.

We shall have to deal with both the practical and theoret-
ical sides of the Rouxian school under several other captions,
but this much may be said now. Developmental mechanics
has one great merit over any other form that elementalism
has taken at any time in the history of biology, in that it
gives ungrudging recognition to many orders of constituent
parts of plants and animals. Organs and tissues of various
grades and classes — cells, nuclei, chromosomes — in short all
the parts of the organism, are accepted as real existences,
only the organism itself being ruled out. In this respect
Roux's elementalism is far more genuinely biological and
scientific than is, for example, the purely chemical form of
elementalism, that form which virtually denies reality not
only to the organism as a whole but to all of its parts except
what in its most general mode of expression it calls the
"living substance."

Superior in some respects as the conceptions underlying
developmental mechanics are to those underlying purely
chemical elementalism, far more superior are they to that
form of elementalism the citadel of whose biological faith
is constructed from deepest foundation to highest pinnacle
of "hypothetical living units," of which Spencer's physio-
logical units, Darwin's pangens, and Weismann's determi-
nants are the most famous examples. The reason why
strictly metajjhysical conceptions of this type all prove to

20 The Unity of the Organism

be so noxious to scientific biology we shall point out later.

Finally, to bring our historical survey to the present
hour, brief reference must be made to the form the contro-
versy has assumed in its very latest stage. To show that
the Mendelian-unit-character-factorial-chromosomal theory
of heredity has become thoroughly permeated by the elemen-
talistic philosophy will be one of the cardinal aims of some
of our critical chapters. This philosophy more than the in-
trinsic importance of the objective discoveries is what has
aroused the imagination and enthusiasm and stimulated the
activity of geneticists, as the new school of investigators of
sexual reproduction call themselves. Reference to this lat-
est phase of biological elementalism cannot serve the future
in any better way, I think, than by calling attention to the
remarkable illustration furnished by these late developments
of the narrowing power of elementalistic philosophy.

A calm and just judgment of what the strongest motive
in philosophical biology is to-day, would be that it is a firm
belief that the most imjDortant problems of the whole living
world are centered in — what? Sex-cells.'^ No, not even in
entities thus large and complex ; but in a few minute and
relatively simple fractions or parts of these cells, the chro-
mosomes !

Viewed broadly both as to historical development and
factual content, we are warranted in being confident of the
triumph of the organismal standpoint at a day not far dis-
tant, this confidence being warranted largely by the fact
that it seems as though elementalism has run nearly its
whole natural course. It has consumed all the material there
is for it to live on, as one may say. It is now engaged in
trying out the very last portion of the organism as the
"seat" or ultimate explanation of life phenomena. This
judgment of the situation becomes especially cogent if the
broadly generic term "chemical substances", be put in the
place of "hereditary substance" or "genes" which are imag-

Introductory 21

ined to make up largely or wholly the chromosomes.

A striking example of the rapid progress made by ele-
mentalism toward its own extinction through contracting
itself to nothingness is furnished by the course of speculation
about ultimate biological units from the period of Spencer
and Darwin to the present moment. Spencer's physiological
units were by no means restricted to the germ-cells but
were held to permeate the whole organism. In this the
doctrine had a strong organismal flavor. And Darwin's
gemmules had an unmistakable organismal leaning in that
they belonged to the organism as a whole at least as much
as to the germ-cells. His conception was one of pan or uni-
versal genesis and not merely of genesis from germ-cells
toward soma. In fact, the main object of his quest was an
explanation of how body, or soma, may influence germ-cells.

After Darwin came the next long step toward elementalist
reductio ad ahsurdum in Weismann's proposal to limit the
efficient ultimates of organization, the determinants, to the
germ-plasm whether this be in sex or other reproductive
cells ; that is, to so conceive the ultimate nature of the or-
ganism that there should be no reciprocal action between
soma and germinal elements ; that the whole movement, both
individual and racial, in organic evolution should be a one-
way movement, that way being from invisible germ to visible
organism.

Finall}^, there has arrived the ultra-modern school, the
geneticists, with those wonderfully efficient instruments of
analysis, the factorial hypothesis of Mendelian inheritance,
and the hypothesis that chromosomes are the "seat" of the
"factors" of heredity. These two hypotheses coupled to-
gether and with the hypotheses that all evolution is by mu-
tation, and that all mutations consist in the dropping out
or losing of factors and characters, need only to be pushed
hard enough and speculative biology will be carried to its
apotheosis and objective biology to its extinguishment.

S2 The Unity of the Organism

How far theorizing has gone on this road is indicated by
the much noticed address by WilHam Bateson, one of the
foremost MendeHan geneticists, as president of the British
Association for the Advancement of Science in 191^. In this
address Bateson suggested, whether with full seriousness or
not no one seems quite sure, the above mentioned hypotheses
of the loss-of-characters method of origin of all organic
species.

The chromosome theory having been elaborated into what
it now is, the easy step, to the conception that the First,
or Original Organism, as something close of kin to a chro-
mosome, has already been taken by an able student, E. A.
Minchin, the imaginary Primal Organism being called by
him "Biococcus." This speculation we shall consider in our
f oraial discussion of the chromosome theory of heredity.

To bring together these suggestions by Bateson and Min-
chin and elaborate them into a complete, well-rounded theory
requires only a biologist, preferably a German, with the
industry and learning and imaginative logic of a Weismann.
This accomplished, the ultimate nature and the evolution
of the whole past, present, and future organic world would
be causally explained by referring it to a primordial chro-
matinic hierarchy which contained the detenniners, or fac-
tors, of all later visible organisms, and from which these
issued by the transformation of latent into actual organisms
throuo;h the removal of factors which inhibit the actuation
of other factors. But practicable as such a complete ex-
planatory theory is, and harmonious as it could readily be
made with certain far-reaching and widely favored concep-
tions in modern physics, it is very doubtful if the enterprise
is ever carried out — at least for any other purpose than as
an illustration of how elaborate and consistent and withal
beautiful a structure can be erected by pure logic.

My main reason for believing the entei-prise will never be
carried through, seriously, is that the organismal stand-

Introductory 23

point has already advanced so far on secure observational
and experimental and inductive foundations, that the scien-
tific uselessness if not folly of such elementalistic systems
will deter working biologists from spending their time on
them.

The barest mention of some of the most important lines
of organismal advance, just referred to, will fittingly close
tliis historical sketch.

From the standpoint of biology in the narrowest sense,
no researches are yielding more of organismal significance
than are those on internal secretions or hormones, or "chem-
ical messengers" as they have been called by Starling, one
of the foremost investigators of these substances. Two
chapters of the constructive part of this work are devoted
to this subject.

Another province in which research is yielding results
scarcely if at all secondary in significance to those coming
from the biochemical realm just mentioned, is that on the
integrating office of the nervous system. The fundamental
and extensive work of Sherrington is of prime importance
here. But a genuinely organismal aspect is recognized in
the tropism theor}^ of Jacques Loeb, which turns out to be
almost as important for our general enterprise as the unify-
ing character of the nervous system.

Finally, the realm of the indubitably psychic life of or-
ganisms, particularly of man, is found to contain much of
the utmost usefulness to the organismal conception. Espe-
cially to be mentioned in this connection is the doctrine
of Apperception as understood and worked out by Wundt,
and its relation to the tropism theory, this relation having
apparently been first pointed out by Royce. A discussion
prominently involving this relation w^ill conclude the con-
structive part of the volume.

24 The Unity of the Organism

Nature and Scope of the Undertaking

The foundation of our enterprise, so far as historic sum-
mary is concerned, being laid, we may now exhibit the plans,
floor-plans and elevations, as architects say, of the super-
structure; but the barest outlines will suffice. Leaving off
figurative speaking, we must now state in bald outline the
central aim of the undertaking. It is to show that while
the two conceptions, the organismal and the elemental, con-
tain much that is thoroughly irreconcilable, there is a great
substratum of truth underlying both. Adhering to the mode
of expression previously used in characterizing the two
points of view, the central idea which we shall try to es-
tablish may be put as follows : The organism in its totality
is as essential to an explanation of its elements as its ele-
ments are to an explanation of the organism. This formula-
tion which has been in service with me for many years in
university lectures and in verbal discussions with colleagues,
is approached, somewhat remotely by several authors, earlier
and later. Thus L. Rhumbler says at the conclusion of the
article Correlation, in tlie Handworterhuch der Naturwis-
senschaften: "One may assume perhaps that each function
of an organ, etc., is bound correlatively to the functions of
all other organs, even though perhaps many times in the
slightest way and through means in part replaceable, so that
by this the organism as a whole is influenced to a definite
degree by each of its organs, and vice versa [that] through
these numberless influences the so-called influence of the
whole upon the parts in turn finds its explanation even
though complicatedly and at present reaching only to some
details." ^^ We have here the Rouxian form of elementalism
at which we have already glanced, but it seemed worth while
to notice this particular expression of it since its advance
toward organlsmalism as contrasted with chemical elemen-
talism is well brought out.

Introductory 25

We may preface a slight expansion of our dogmatic
formula by asking the question, "How is it that the prin-
ciple, embodied in such phrases as the 'Organism as a whole'
so confidently used by eminent investigators, sliould be so
distrusted by most biologists as to give it little influence on
biological conceptions?" The proximate reply is that for
most biologists the notion is too vague and general to be
of high and permanent worth. One statement of this de-
preciatory estimate is that to take the organism in its en-
tirety is to take it unanalyzed ; and this, so such a view
holds, is superficial and contrary to the whole purpose and
spirit of modern research. To analyze complexes of natural
phenomena, that is to reduce them to their elements is, ac-
cording to this view, exactly what makes science science.
Scientific knowledge in biology as in all other fields, is ana-
lytic knowledge; and conversely, analytic knowledge not
only is science, but (at least so says full-fledged elemental-
ism) is the whole of science. Our undertaking will require
us to combat, incidentally but yet vigorously, this view.
Stated positively, while assiuning as science always does as-
sume, the validity of analytic knowledge of nature, we shall
contend that synthetic knowledge of nature is not only valid
also, but that it is as foundational and essential a part
of science as is analytic knowledge. Furthermore we sliall
touch briefly, but as we believe very fundamentally, the
question of the nature of synthetic knowledge itself.

In accordance with this general statement of purpose,
I hope to be able to clear the conception of the "organism"
taken alive and whole, of the vagueness that has hitherto
enveloped it and make it as clear, as sei-^^iceable, and as in-
dispensable to science as are "foot"' or "liead" or "brain,"
or "eye" or "muscle" or "cell" or "ovum" or "nucleus"
or "chromosome" or "nucleo-proteid" or "ptyalin" or any
other fully accredited and unescapable biological entity.
Let me state the case from a slightly different angle, attach-

^6 The Unity of the Organism

ing it to a quotation from E. B. Wilson given in our historic
survey. This quotation is : "The only real unity is that of
the entire organism." This I would modify thus : The entire
organism is not the only real unity but it is a real unity, and
represented by the highest animals, especially man, is the
supreme unity.

Whatever warrantableness there may be in the prejudg-
ment among biologists to the effect that the "organism as
a whole" connotates "the organism unanalyzed" even if not
unanalyzable, will I hope be met largely by the phrase "Or-
ganismal Integrity" of which I make much. Obviously, if
one stops to reflect a little, "the organism as a whole" if
taken strictly, could mean nothing less than the organism
and all of its parts. The whole would not be the w^hole if
some of its parts were omitted ; so even from this standpoint
one might contend that "the organism as a whole" must
mean the organism taken wholly, that is, through and
through, no part being neglected, and that consequently
instead of connotating the organism unanalyzed, in reality
it connotates just the opposite and thus indicates the only
starting point for complete analysis of the organism. But
"organismal integrity" not only carries all the other phrase
implies so far as mere totality is concerned, but it does more
in that integrity and its etymological kindred, point defin-
itely not only to the parts, but to them as interdependent.
The past participial form of the verb integrate, i.e., in-
tegrated, we shall find particularly serviceable, it being sus-
ceptible of use in the comparative degree. The greater or
less extent of integratedness of organisms we shall need to
speak much about as we proceed. Again such tenns as
integration, integrally, and integrality will, upon occasion,
contribute to precision and flexibility of expression. The
kinship, both as to terminology and conception, between
what is foreshadowed in the justification of the phrase or-
ganismal integrity and Herbert Spencer's Physiological In-

Introductory 27

tegration will not escape the notice of any reader acquainted
with Spencer's ideas, particularly if he be at the same time
acquainted with the conception as adopted by O. Hertwig
and made the third law in his Theory of Biogenesis. Hert-
wig's elaboration of this law contains more probably that
accords with my central thesis than does any other writing
known to me.

A brief on the procedure which will be followed in devel-
oping our thesis may now be given.

Part I will be devoted to setting fortli efforts that have
been made in recent and present-day biology to deal with
several great classes of the constituent ])arts or elements
of organisms in accordance with the eknientalist theory.
If my basal proposition be true that tiie organism taken
alive and whole is as essential to an explanation of its ele-
ments as its elements are to an explanation of the organism,
then it would follow that all attempts to assign explanatory
values to the elements in their relation to the whole organ-
ism, while at the same time denying either expressly or
tacitly, similar values to the entire organism in its rela-
tions to the elements, must fail in large degree.

And here comes in sight a vitally important aspect of my
general standpoint. Were the basal proposition just stated
handed out as a postulate, that is, as a proposition the ac-
ceptance of which is demanded without proof, or were it
even held to need no other proof than such as might be ad-
duced by syllogistic reasoning alone, in the manner, for ex-
ample, that both Aristotle and Lucretius mainly supported
their views, our task would be comparatively simple. As an
illustration of how easily organismalism could be demon-
strated by this method, take the case of the relation of the
organism to its cells. We should first point out in general
terms what characters certain groups and classes of cells
might be expected to show in accordance with the hypothesis
that the larger structural and functional requirements of

28 The Unity of the Orgamsm

the organism influence its elements, and then search among
the cells for examples of such influence. But this, the de-
ductive mode of reasoning, is a complete antithesis to that
on which we shall chiefly rely in this treatise, indeed to that
on which biology always has chiefly relied so far as its prog-
ress has been healthy and vigorous and straight ahead.

Holding, consequently that the proposition must be in-
ductively established if it is to be established at all, the
heavy task devolves upon us of examining, as above in-
dicated, a great range of the biological field to see how it
fares with the two opposing hypotheses (and viewing the
theories from the present stage of our enterprise, they
should be considered as hypotheses in the strictest sense)
when they are tested by a great number of fully authen-
ticated observations. From this general statement it is
apparent that the first division must be for the most part
distinctively critical. That, however, it is not wholly of
this character, I trust will be patent enough to the attentive
reader.

Part II will consist of a systematic presentation of the
fullv established inductive evidence which, if fairlv consid-
ered, compels, as I believe, the adoption of some such
general view as that here defended and would be called,
according to nomenclatorial precedent, organismalism.

On behalf of this unauthorized and rather bungling word,
I make no plea. In fact, the use of it goes against the grain
with me somewhat and I avoid it as far as possible. The
sum and substance of the situation is, though, that the term
seems to force itself upon me at times. It corners us, so
to speak, and will not let us escape without taking it u]) and
carrying it with us. But perhaps the possession of such
power as this is just wliat entitles new words to live. If so,
and should tlic idea prevail for which the word stands, the
word will prevail too unless some one liaving special com-
petency in fabricating words finds a better. Which of these

Introductory

29

alternatives may befall is imniaterial. My only concern is
for the idea. If that survives and flourishes I shall be satis-
fied, no matter under what name it becomes known.

1. Aristotle ('11)

2. Lucretius

3. I>ocy 139

4. Merz II, 240

5. Saint-Hilaire 314

(). Schwann & Schleiden 191

7. Whitman ('93) 119

S. Whitman ('88) 49

9. Wilson ('93) 9

10. Lillie, F. R 237

11. Lillie, F. R 245

12. Lillie, F. R 251

13. Lillie, F. R 202

14. Whitman ('93) 123

15. Whitman ('88) 43

16. Lillie, F. R 253

17. Lillie, F. R 258

18. Roux ('12) 287

19. Roux ('12) 241

20. Roux ('12) 163

21. Handworterbuch II, 736

Chapter II
THE ORGANISM AND ITS MAJOR PARTS

Reflections on the Problem of Individuality in the living

World

THERE has been a great deal of inconclusive discussion
of late years, about the nature of the organic indi-
vidual. Biologists holding the natural-history viewpoint
have never had much difficulty in making up their minds as
to what an individual is, but many experimenters, encounter-
ing problems presented by the parts of an individual and by
individuals as parts of a society, have tended to dodge the
issue — have attemjjtcd to find a solution to the puzzle of
individualit}^ by the rather naive method of changing their
definitions of it.

To get some clear-cut idea on this question, out of the
welter of nebulous notions that prevail at present, is so im-
portant for our general discussion that we can afford to
stop for a moment to consider it.

A homely and common illustration will serve as a starting-
point. When a scientific dairyman is buying a milch cow
or a bull, the deciding factor in the deal is usually what he
calls the animal's "individual performance." That is, while
various separate "])oints" are taken into consideration and
pedigree lists are consulted, the final decision is based not
so much on these as on the cow's record as a milk producer
or the bull's as a sire of good calves. In the estimation of
the purchaser, the animal stands or falls on its own merits
as an individual.

30

The Organism and its Major Parts 31

While the individual plant docs not appear quite so con-
spicuously in plant husbandry as docs the individual in ani-
mal husbandry, it is still never a negligible, and is often an
important element. This is especially true in horticulture,
where individual performance is subject to much the kind of
testing that is applied to the individual animal, namely that
of seasonal repetition. In a well kept orchard, for example,
the individual tree holds a prominent place.

To question the reality of the individual cow or apple
tree would be, to a breeder or orchardist, equivalent to
questioning the reality of any such animal at all as a cow,
or any such plant as an apple tree. Yet a considerable
number of zoologists and botanists have been thrown into a
distracted state of mind as to the reality of the individual,
especially among the lower orders of plants and animals.
Botanists have been particularly subject to this malady,
obviously because in none of the plants, not even the highest,
are the individuals so thoroughly integrated as they are in
most animals, particularly in the higher classes. And so,
as we shall see presently, some speculative botanists have
gone to the ridiculous extreme of asserting that there is no
such thing as an individual plant.

What, exactly, is the matter with biological reasoning
which lands men in such absurdities? For absurdities they
surely are, even though given the habiliments of science.
Test the matter this way : If I look at a tree and a man
standing beside each other, there is, so far as this observa-
tion is concerned, not a shred of valid objection against
applying the term "individual" to each. The one is an
individual tree and the other an individual man, and the
individuality of neither is a whit less certain or more cer-
tain than that of the other, as I now perceive the two.

But as I now perceive the two is exactly what we are
here discussing. For anybody to contend that one of these
beings — the man' — is an individual, while the other — the tree

32 The Unity of the Organism

— is not, merely on the ground of what is learned by later
study about the differences in makeup of the two, is literal
nonsense. It is a virtual denial of the validity of oberva-
tional knowledge. Granted that science can not rest satis-
fied with "common-sense" knowledge, there is still no ground
for repudiating all commonsense.

Attempting to ascertain what the trouble is with biolo-
gists who reason thus about individuality, one soon dis-
covers that the botanist who deals with a tree thus unjustly
quite ignores the obvious and unescapable fact that the raw
material of all his botanical knowledge is individual plants
taken one after another; that for trees there is an each tree;
that each, as it actually stands before him, is one, not two
or three or any other number ; and that it is not in the least
confusable witli any other tree, no matter if several are
connected together by their roots or in some other way.
These confused-minded persons either ignore the patent facts
of observation., or if their sophistication is refined, they deny
the validity of the "mere perception" of an individual when
that way of predicating individuality is measured against
supposedly more fundamental principles of scientific knowl-
edge-getting, as analysis is held to be.

This question of more and less fundamental principles
of scientific procedure, especially those involved in analysis,
is undoubtedly of great importance. But undoubtedly, too,
it is a question of the nature of scientific knowledge rather
than of the nature of plants and animals, so does not fall
within the scope of such a treatise as the one now occupying
us. The question before us is that of the nature of the in-
dividual organism.

As soon as we see the necessity of separating these two
questions, and address ourselves to the strictly objective
question, we perceive that the difficulties center around the
fact that no individual plant or animal is simple in its con-
stitution, but in alniost all cases is exceedingly complex,

The Organism and its Major Farts 33

The kernel of the difficulty arising from the complex make-
up lies in the fact, emphasized by recent investigations, espe-
cially those on regeneration, that in very many animals and
plants, when the individual is artificially divided, parts of
individuals have remarkable powers of independent life, even
to the extent of reconstituting themselves into other indi-
viduals as perfect as the one that was divided. The reason-
ing from these facts is, essentially, that because a given in-
dividual may divide or be divided artificially into two or
more parts, which may in turn develop into other individuals
like the original, the original was therefore not a single in-
dividual. In other words, individuality is denied these or-
ganisms because of what parts of them can do when severed
from the whole. The unity, the integrity of the individual
is called in question, not on account of what it is here and
now, but on account of what the parts may do after they
have heen severed, naturally or artificially, from the original
unity.

No biologist, and especially no organismal biologist, would
minimize the significance of the fact that the severed parts
of many organisms possess such remarkable reconstitutive
powers. The organismal biologist, I assert, is especially
interested in the phenomena because they are to him unique
and unanticipated evidence favorable to his general stand-
point. What he denies is that the phenomena count a scin-
tilla against the reality and essentiality of the individual.
He points out that their importance, so far as the prob-
lem of individuality is concerned, is not that they show much
about the ultimate nature of the individual's unity, but that
they do show much about the degree of that unity.

The Individual Plant and Its Parts

The purposes of this chapter will be best served by de-
voting a section to examining a few efforts which have been

34 The Unity of the Organisin

made to interpret the organism in accordance with the
theory which denies its individuahty. Our first instance will
be taken from botany. But before proceeding with this, it
is desirable to point out that some of the most distinguished
botanists, especially physiological botanists, have recog-
nized the unity of the plant without stint or cavil.

We appeal to only one of the botanists of this class,
PfefFer. In The Physiology of Plants, he says : "The in-
timate correlation of the entire vital mechanism renders it
probable that every excitation exercises some effect upon
other manifestations of irritability, even though this effect
may not always be directly perceptible."^

Again : "In the plant community the activity of every
cell and of every organ is subservient to the common weal,
and may, when necessary, be modified as already indicated
so as to fulfill the changed requirements of the whole. "^

It is true, I believe, that the mode of thought about plants
illustrated b}^ these quotations is characteristic of botanists
in whom observation and speculation maintain a due bal-
ance; botanists with whom, in other words, speculation has
not got the upper hand of obsei'vation.

It is highly significant that one of the most pronounced
and, so far as I have discovered, earliest authors to specu-
late on the non-individuality of the plant was Schleiden, one
of the fathers of the cell-theory. In his famous Contribu-
tion to Phytogenesis we read in a discussion of the individu-
ality of plants : "In the strictest sense of the word, only the
separate cell deserves to be called an individual."^ Elabor-
ating this notion, "The woody stem," he tells us, "cannot
come under the idea of a plant." And further: "It neces-
sarily pertains to the notion of a plant, that it produces
foliaceous organs on its stem, yet there is no tree which
produces leaves."^ This last statement sounds, the author
admits, rather paradoxical, but, he contended rightly
enough, the mere circumstance of its sounding paradoxical

The Organism and its Major Parts 35

\

docs not prove it false. Since, as we have previously seen,
Schkiden's brand of elcnientalisni necessitated the sacrifice
of the individuality of the 2)lant to that of tlie cell, our
critical examination of it belongs properly to our examina-
tion of the cell-theory. Here, consequently, we do no more
than point out that Schleiden himself did not succeed in
carrying through fully his simple denial of the plant's unity.
The oneness of the young dei'dopincj j)lant was an obstacle
to his theory, even though he seems not to have been aware
of the fact. "After the wood}' mass is formed, we miss,"
he says, "the influence of the law of formation, which until
then had without exception directed the growth of the entire
jilant in all its parts. "^

Schleiden seems to have felt no difficulty in his conception
that the "law of formation" w^hich "directed the growth of
the entire plant in all its parts" could be accounted for by
the "separate cell," the only individual "in a strict sense."
His immunity from qualms on this score was due probably
to the fact that, being an "ultimate problem" botanist in-
stead of a naturalist really interested in plants, it did not
occur to him that the question of how^ the cells could explain
the fact that in one instance the "entire plant in all its
parts" shbuld be an apple tree, in another an oak tree, in
a third an orange tree, and so on, might be considered a
really important one by somebody.

We now pass to the examination of a single modern in-
stance of the attempt to "explain away" the individuality
of the plant. The principle made use of in this attempt is
that of symbiosis, which is a sort of partnership between
organisms of different species, so close in some cases as to be
really organic. Although I do not know that the example
I have chosen has had much recognition among botanists, it
yet seems justifiable to use it since it is certainly typical,
even though possibly somewhat extreme. It is taken from H.
C. Davidson, an English botanist, his publication being en-

36 The Unity of the Organism

titled The Nature of the Plant. After illustrating the prin-
ciple of symbiosis by referring particularly to the case of
the mutually dependent combination existing between the
flat-worm Convoluta roscoffensis and a green alga, recently
well studied by Keeble and Gamble, Mr. Davidson goes on
to argue that if a typical plant, a tree for example, be
considered to be a like sjanbiotic complex, "much that
has been dark in the vegetable world becomes clear."^

The members of the partnership in the plant so con-
ceived would be the flowers, equivalent to the "hermaphro-
dites and males and females" occurring in the world of in-
sects, and the buds equivalent to the underdeveloped females
or neuters. Among the darknesses enveloping plant life
which the author believes would be illumined by this theory
he mentions that of the plant's individuality. In the light
of the theory it becomes obvious, the author holds, that a
"plant is not, as is generall}^ supposed, an individual entity,
but in reality a group or family of individuals, associated
within a common protecting envelope, the bark, and upon a
common root for the common good."^ These "associated
individuals" Mr. Davidson calls ylantagens since, he says,
"they cannot well be written about unless they have a name."

Another meritorious thing about the plantagen theory,
its inventor believes, is that it removes the difficulties in the
way of the germ-plasm theory of Weismann, presented by
plants. The type of reasoning which has given rise to this
rather ingenious speculation will receive due attention in
various parts of this volume. I bring up the case here only
as a specific instance of "certain general tendencies to er-
roneous reasoning" above referred to. There is always the
inclination to ascribe more casually interpretative value to
some of the parts of organisms in their relation to other
parts and to the whole than actually belongs to them. In
the present instance this eff^ort is seen in the fact that both
the asexually and sexually propagating elements of any

The Organism and its Major Parts 37

given plant are treated as though they were distinct, ulti-
mate data, whereas they certainly are not. The term
"symbiosis" was introduced into biology exactly for the
purpose of expressing the fact that individual organisms,
usually of very distinct species, get together in an intimate
relation wherein one or both members of the partnership
gain some advantage, each at the same time preserving its
unmistakable identity. There is certainly not the slightest
evidence that tlie asexual and sexual parts of plants were
originally independent of each other in this way.

Let us accept momentarily (since his speculation is de-
pendent on our doing so) Mr. Davidson's contention that
"germ-cell must develop from germ-cell, bud from bud, in-
dividual from individual." Even so, no biologist who is a
genuine believer in organic evolution, that is, in the teach-
ing that all organic kinds have descended from ancestors of
different kinds, can allow that "much tliat has been dark
in the vegetable world" is made any less dark by the as-
sumption of such a fundamental independence of germ-cells
and germ-buds and "individuals" until he is informed as to
the ancestry, not only proximate but remote, of germ-cells
and germ-buds and "individuals."

The kinship between these modern speculations about sym-
biosis and an ancient notion due, it seems, to Empedocles,
comes to light at this stage of the discussion. What that
notion is we shall see presently. Mr. Davidson's symbiosis
theory of plants involves, he points out, his theory of plant-
SigenSy which last theory involves, as he rightly says, the
conception that "germ-cell must develop from germ-cell,
bud from bud, individual from individual." But any ten-
year-old farmer's son may know this statement is not true.
Keeping the fonn though not the meaning of Davidson's
expression, such a boy can assert that germ-cells develop
not only from germ-cells but also from buds, and that buds
develop not only from buds but also from germ-cells.

B8 The Vnity of the Oi'ganism

Following a killing frost in southern California a few
years ago, thousands of lemon trees whose normal foliage
had been destroyed put forth great numbers of new shoots
on their trunks and largest branches. Such new shoots may
occur anywhere and everywhere on the trunk and branches,
and since they rarely arise, so long as there is no occasion
for them because of the activities of the normal foliage, the
term "adventitious"* is appropriately applied to them. So
lemon-tree germ-cells and lemon-tree plantagens, or speak-
ing in terms free from speculative sophistry, lemon-tree
seeds and lemon-tree buds, are dependent for their origin
upon lemon trees. In other words, the tree is as essential to
a causal explanation of the seed and the bud as the seed
and the bud are to a causal explanation of the tree.

Reproduction by adventitious buds among the higher
plants is so important from the organismal standpoint that
we must consider it a little further. One additional fact
which the reader should appreciate is that the method is by
no means an exceptional and insignificant thing in plant
economy. It is a regular way many trees have of perpetu-
ating themselves. An illustration of this even more striking
than that of the lemon tree is furnished by the Coast Red-
wood of California {Sequoia sempermrens). A stump of
this tree, even a stump that has passed through a severe

* The question of adventitious or cambium buds from lemon trees
seems not to have received much attention from botanists. Judging from
the distribution of the new growths in such an epidemic, as it miglit
be called, of budding as that which takes place imder conditions like
those here mentioned, there is scarcelv a doubt that verv many of the
new l)ranches arise quite independently of previous bud germs; in other
words, from some source not germinal mitil it becomes so under the
special conditions. The only experimentation on bud production in the
lemon with which T am acquainted has been carried on by Prof. H. S.
Reed of the Citrus Kxperimeut Station of the University of California,
at Riverside. Doctor Reed has kindly shown me the results of his
work and pennitted me to make use of them in this coimection. So
far as these experiments go, it seems that while leafless pieces of
branches kept under suital)le contlitions readily put out undoubted cam-
bium buds, these produce roots only.

The Orgatiism and its Major Parts 39

forest fire, will put out thousands of shoots. That these
arise from the cambium I am assured by Dr. Percy Brandt,
a botanist who iias given special attention to the matter.
Now I ask the reader to reflect on what is before us here.
When the tree's life not merely as an individual but as a
potential parent is destroyed, so far as all visible evidences
are concerned, one of the general tissues of the stump, its
cambium layer, proceeds forthwith to do what under the
normal life-conditions of the tree it does not do, namely,
produce new buds, each one a potential new redwood tree.
The indubitable facts compel us to recognize that any part
whatever of the cambium, at the base of the tree at least, is
capable of being diverted from its normal function and
made to do what it would not do except for the special con-
ditions imposed. I say it is "made to do" these things rather
than merely that it "does" them as though from its own
inherent nature alone, simply because it does not do them
unless they are subjected to the very particular conditions
which are imposed, namely those of the destruction of the
normal propagative parts of the tree.

Whether one has in mind the question of how the whole
cambium, normally not reproductive, becomes endowed with
reproductive power; or the negative side of the question,
that of why it should not be reproductive under normal
conditions, there is no way of reasoning adequately about
the causes of the phenomena without bringing in the tree
as a structural and functional whole. The redwood tree
as a whole is essential to a causal explanation of the ca-
pacity of its cambium tissue. Efforts to escape such a rec-
ognition by resorting to conceptions like those of germ-
plasm and plantagens is unmitigated sophistry.

The Individual Animal and Its Parts

So obvious is it that in the full-grown individual of any
of the higher animals the organs and parts are in some

40 The Unity of the Organism

measure an adaptation to one another and have some struc-
tural dependence upon and correlation with one another,
that it would be superfluous to enumerate the facts and di-
late on their significance. The subject constitutes no small
part of the older comparative anatomy and physiology.

Almost as obvious is it, too, that the major parts of such
animals are incapable of long-continued life when they are
severed from the whole. But the great capacity for con-
tinuance in the living state possessed by certain parts of
some classes of animals has attracted much attention, most-
ly because of the intrinsic physiological and morphological
importance of the phenomena themselves rather than of any
assumed support afforded by them to the doctrine of au-
tonomy of the parts in a strictly elementalistic sense. But
these and other facts of organ-independence have been used
as a groundwoi^k for certain elementalistic conceptions of
the organism which, viewed in their liistorical setting, are of
much broader interest. The historical setting to which I
refer goes back to a speculation by that primal elementalist
Empedocles, and may be called an organ-assembling theory.
The modern relatives of this old theory may be called ag-
gregational theories, and are typified by the conception that
the normal individual plant or animal is an affair of sym-
biosis or secondary union of previously independent organ-
isms. A concise statement of Empedocles' hypothesis is
found in the De Generatione Animalium of Aristotle (Book
I, 722^, 20) : "in the time of his 'Reign of Love' says he
[Empedocles], 'many heads sprang up without necks,' and
later on these isolated parts combined into animals."

Symbiosis, as illustrated by Davidson's speculation, means
a partnership between individual organisms of different
species so intimate as to make each member of the combina-
tion really dependent to some extent on the other. A con-
siderable number of such cases are now known in both bot-
any and zoology. Perhaps the most striking example is

The Organism and its Major Parts 41

that of the partnership between an alga and a fungus to
make a Hchen. The kinsliip between such a speculation as
that of Empedocles concerning the origin of the individual
and the modern speculation which would have the individual
arise sjmbiotically is unmistakable. The most important
likeness between the two conceptions is the fact that both
are fundamentally wow-evolutional. The isolated heads,
necks, legs and arms of the ancient Greek, like the genn-
cells and germ-buds of the modern Englishman, are just
taken because they are necessary for the particular specu-
lation. The question of how heads and legs and of how
tree germ-cells and germ-buds arose in the first instance is
not raised, or if it were it could be answered in accordance
with the basal principle involved, only by assuming another
and another and another set of elements of the same kind,
ad infinitum. In a word, the theory really contains no pro-
vision in a truly organic sense for transformation, which is
the very essence of the conception of organic evolution. It
should be noticed that the principles of Love and Hate ap-
pealed to by Empedocles and that of struggle and survival
appealed to by neo-Darwinians are held to explain not the
origin of the heads, legs, etc., or of the gerai-cells and germ-
buds, but the origin of actual animals and plants from the
respective elements once the elements are at hand. In a
word, expressing the limitations on this mode of theorizing
in the familiar language of Darwinism proper i^not neo-
Dainv^inism), the natural selection hypothesis does not pre-
tend to explain the origin of variations and variants, but
assumes them. What we are bound to see if we look at the
relevant facts squarely is that the doctrine of organic evo-
lution involves the conception of ancestry as fundamentally
as it does that of progeny. Observation finds organisms
produced hy parents no less indubitably and inevitably than
it finds them giving origin to progeny, so that the effort
constantly recurring in recent biology to find ultimate se-

42 The Unit?/ of lire Orgainsm

curity in something or other to which the word genesis
can be attached, but which can yet be conceived as not sub-
ject to transfgrmation, is everywhere hostile in a funda-
mental sense to the descent theory.

The latest manifestation of this hostility is the gene or
factor theory of the ultra-Mendelians among present-day
geneticists. The gene as conceived in the genotype theory
turns out on close inspection to be still another something-
or-other, which though not itself transformable can explain
transformation in something else, and which has been ap-
pealed to by generation after generation of elemental-
minded theorizers about the origin of living beings, from the
ancient Grecian period at least. Jennings, one of the ablest
of the experimental geneticists, and one vf\\o has a genuine
regard for the visible as contrasted with the invisible and
hypothetical data of organic genesis, has lately pointed out
the essentially non-evolutionary character of the genotype
theory. "The whole conception," he rightly says, "is in
its essential nature static ; alteration does not fit into the
scheme." ^ We shall have occasion to consider this new
phase of the non-transformism in other connections. Our
purpose in referring to it here is merely to point out where
it belongs in the general scheme of genetic theorizing when
this scheme is viewed historically. Biology at present needs
few things more sorely than a system of reasoning which
shall not beget in students the mental habit of allowing re-
condite concepts and postulates and strange words to cast
every-day, familiar facts into outer darkness. One of the
most obvious and indubitable facts about all organic de-
velopment is transformation. The development of a chick
from a hen's egg is accomplished not merel}^ by a great in-
crease in size, but by the profoundest sort of transforma-
tion, this being deployed, as one may say, through a long
series of stages grading insensibly one into another. And
so with every other ontogeny, animal ontogen^^ especially.

The Orgfivism and its Major Parts 43

The working out of these innumerable transformational
stages constitutes the science of embryogenetics.

This transformational character of individual develop-
ment, or ontogenesis, is even more startling, and in some
ways confusing, in certain of tlie lower animals like the
coral polyps, where secondary individuals arQ produced
asexually but do not become whollv severed from the stock
or colony. But each multiple animal, as these may be called,
is a single germ-cell in the earliest stage of its life, and this
alone is proof of a certain measure of individuality of the
whole "colony" produced from the same egg. Indeed, some
zoologists, Huxley for instance '* have used this as the sole
or chief criterion of organic individuality, and have defined
the individual as all that arises from a single germ-cell.
There can be no doubt about the validity and usefulness of
this conception as one criterion of individuality, even though
it does not constitute a basis for a complete definition. An
exceedingly fertile field of zoological research is that of the
varying degrees and exact character of functional as well
as developmental integration in these metagenetically built-
up, loose animal individualities. Much is already known
on the subject, but very much is not known, and to extend
knowledge in this field is one of the urgent needs of zoology.
The subject received much more attention, relatively, two
or three decades ago than it does now^ ; so that few of the
investigations on which he have to rely have had the benefit
of the best technical methods. We may confidently antici-
pate that when the later technique of studies on neuro-mus-
cular stimulus and response and on internal secretions are
applied to metagenetic group-individuals, such as are found
in many of the coelenterates and in some of the tunicates,
much new light will be thrown on the interrelationship of
the members and organs in these poorly unified individuals.

But — and the point is cardinal for us — no matter how
much or what new knowledge we get as to the members and

44 The Viiity of the Organism

their relations to one another in these individuals, we are
sure that that knowledge will not militate in the least against
the reality of the individuals, nor against the fact that every
individual has some measure of unity, of integratedness,
structural, functional and developmental.

REFERENCE INDEX

I'

1. Pfeffer 18 6. Davidson 407

Q. Pfeffer 27 7. Davidson 405

3. Schwann and Schleiden.. 258 S.Jennings ('17) 283

4. Schwann and Schleiden.. 259 9. Huxley ('52) 146

5. Schwann and Schleiden . . 261

Chapter III

THE ANIMAL ORGANISM AND ITS GERM-LAYERS

The Germ-layers, Their Role In Development, and the

Germ-layer Theory

^^TRICT fidelity to the natural sequences of biological
^^ knowledge as viewed in this work would not permit us
to introduce at this early stage of our discussion such a
subject as that of germ-layers, or indeed any other purely
developmental aspect of the organism, but would require us
to deal more fully than we yet have with the completed or-
ganism. However, our general attitude having much of the
pragmatic about it will be broadly tolerant in the matter of
adapting methods to ends sought. This way of beginning
is chosen for the two-fold reason that in this domain my
own researches first came upon facts which contributed
very largely to the ideas underlying this whole undertaking,
and also that these and kindred facts constitute some of the
most striking evidence we have of the ability of the organism
to gain its developmental ends in unusual ways when the
usual ways chance to be obstructed — evidence, in other
words, of the domination of the organism as a totality over
its parts.

From its very beginning with Wolff and von Baer, mod-
ern embryology has recognized that animal embryos pass
through a stage in which the body consists of little more
than unifomi layers of cells, first one, then two, then three,
and finally, in several classes of animals, four ; these being
disposed one inside the other and more or less regularly

45 . ,

46 The Unity of the Organism

concentric. From these layers all the organs and tissues
are developed by a great variety of unequal thickenings and
foldings and concentrations and cellular differentiations.
Details are not necessary for our purpose. As expressed by
one standard textbook of embryology, these layers are as
a rule "structural units of a higher order than the cells."
"Primary organs of the animal body" is another term ap-
plied to them. The appropriateness of the descriptive term
"germinal" applied to these layers is found in the fact that
the tissues and organs are generated from them.

The passage of the embryos of so many different animals
through this layered condition makes the phenomenon a law
of animal ontogeny or individual development of wide ap-
plicability and this law, looked at from the standpoint of
the full-layered stage, is found to reach in both directions,
i.e., backward to the mode of origin of the layers from the
single undivided egg-stage of the organism, and forward to
the mode of origin of the tissues and organs from the layers.
Because of the great measure of uniformity among many
groups of animals which pervades the passage of the em-
byro from the egg-stage to the full-layered stage, embry-
ologists have been able to recognize and so name several
stages, the descriptions of which are in many cases very
clear and precise. The best defined of these are the morula
or cell-cluster stage, the blastula or one-layer stage, and the
gastrula or two-layer stage.

On the other hand, looking from the full-layered stage
toward the completed organism, a dominant uniformity in
developmental procedure, i.e., a conspicuous law of onto-
genesis, is seen in the part contributed by each layer to the
completed animal. Since it is this aspect of the matter that
particularly concerns us, we must go into a little more
detail. As laid down in the standard text-books of embry-
ology, three layers are recognized, namely the outermost,
called the ectoderm; the middle, called the mesoderm (in

The Animal Organism and its Germ-Layers 47

nianj groups split into two, thus making a four-layered
stage) ; and the innermost, called the endoderm. The deriva-
tives of these layers, as typically stated, are : From the
ectoderm, "The epidermis and its appendages, hairs, nails,
epidermal glands, and the enamel of the teeth. The nmcous
membrane lining the mouth and the nasal cavities, as well
as that lining the lower part of the rectum. The nervous
system and the nervous elements of the sense-organs, to-
gether with the lens of the eye." From the endoderm: "The
mucous membrane lining the digestive tract in general, to-
gether with the epithelium of the various glands associated
with it, such as the liver and pancreas. The lining epithe-
lium of the larynx, trachea, and lungs. The epithelium of
the bladder and urethra." From the mesoderm: "The vari-
ous connective tissues, including bone and the teeth (except
the enamel). The muscles, both striated and non-striated.
The circulatory system, including the blood itself and the
lymphatic system. The lining membrane of the serous cavi-
ties of the body. The kidneys and ureters. The organs of
reproduction." ^

The summary here given is taken from The Development
of the Human Body, by J. Playfair McMurrich, and conse-
quently has special application to man ; but it is a presen-
tation of what is usually understood to be contained in the
germ-layer theory applicable to all the metazoa with cer-
tain general modifications for the groups like the coelenter-
ata which never advance to the three-layered condition. As
thus treated the germ-layers are structures as indubitably
as are bones or muscles or feet or hands or brains ; and the
now unquestioned fact that they are so alike in both struc-
ture and relations in so great a range of animals, and give
rise with such constancy to the corresponding parts of
the completed animals, has been and ever must be of great
importance for the interpretation and comprehension of the
vast complexity of animal structure. Says one of the fore-

48 The Unity of the Organism

most embryologists : "As our knowledge of the development
from the germ-layers has grown, we have learned with ever-
increasing certainty that each germ-layer has its specific
role to play." ^

Are Germ-layers Developmental Organs and Subservient to
the Developmental Requirements of the Organism?

But after all this has been fully and gladly granted, there
still remains much to be said concerning the deeper biologi-
cal meaning of the germ-layers, and the different attitudes
of mind which different biologists may assume, indeed do
assume, toward these layers. What we have to offer on this
subject will be from the standpoint of the difference bet-
tween the elemental and the organismal ways of looking at
biological phenomena generally. This difference may be
brought out by asking, does the obviously very general rule
of origin of the tissues and organs from the different layers
hold with genuine universality, that is, in all animals in
which the three (or four) layers occur, and under all cir-
cumstances of development in every animal .^^ Or, putting
essentially the same question, but modified so as to show
more clearly its relevancy to the organismal and elemental
standpoints : are the germ-layers, when looked at as "struc-
tural units" or elements "of a higher order than cells" so
fundamentally independent of one another and of the or-
ganism as a whole that they always and under all conditions
must give rise to just the tissues and parts typically arising
from them, and nothing else? Or, shifting the point of view
a little : has the organism, as such, needs and abilities so
paramount that it is able to realize these needs by modi-
fying to any extent the developmental course usual to the
gorni-layers?

The Animal Organism and its Germ-Layers 49

A Negative Answer to the Question in the Last Section
Expected of Element alist Biology

Any one who perceives the essence of elementalism and
so has seen that it perforce implies a denial of causal
power of the whole organism oA^er its parts in development
will foresee what answer biology as strongly elementalist as
the science has been in the recent period wall be likely to give
to these questions. It will not be satisfied with basing its
expectation that an organ or tissue has arisen from a par-
ticular germ-layer solely on the fact that in all hitherto
obsers^ed cases it has so arisen. The contention may be ex-
pected that the independence and autocracy of the layers
are in no way subject to modification to meet the require-
ments of the organism as a unit: that in case of conflict
between the needs of the organism as such and the proper
powers of the layers, the organism must accommodate itself
to the layers if any accommodating is to be done. As a
matter of fact the germ-layer theory has been defended with
great vigor in just this hard-and-fast way. Nerve tissue
must arise from ectoderm if it comes into existence at all.
Under no circumstances is it permissible to believe it to have
arisen from either of the other layers. Muscle tissue must
arise from mesoderm (or mesenchyme) or not at all; and
so on, according to this way of viewing developmental phe-
nomena. Numerous biologists say in substance that the
entire teaching of embryology, anatomy, histology, and
pathology, should be based on the doctrine of the germ-
layers.

Evidence That Germ-Layers Are Thus Subservient to the

Organism

This brings us to the facts previously alluded to as
having played so considerable a part in genex'ating the sys-

N

50 The Unity of the Organism

tern of ideas set forth in this treatise. Put into a nutshell,
the case is one in which the ontogeny or individual develop-
ment being much out of the ordinary, several of the germ-
layer relationships prevailing in ordinar'y ontogeny are
profoundly modified, the end-results being the same as that
resulting from an ordinary development. To be explicit
on a single point, an instance is presented in which the
nervous s} stem arises not from the ectoderm in accordance
with the general rule, but from the endoderm, this profound
deviation from the typical being explicable, seemingly, from
the generally different entogenetic course followed in blasto-
genesis. The case, well known to embryologists but insuf-
ficiently heeded, is one of bud propagation in some of the
compound ascidians. I was not the first to observe the
uniqueness in this form of development ; but since in one of
the instances studied by me the facts are probably clearer
than in any other that has been examined, it will be best
to present in the barest outline only, the evidence furnished
by this one case. Full details are in my memoir.^

{a) Evidence From Bud Propagation in Compound Ascidians

We will confine our attention almost entirely to the one
species, Goodsiria dura (according to the later classifica-
tion Metandrocarpa dura), an abundant species on the
coast of California. To understand the particular points
with which we are concerned, it Avill be necessary to say a
few words about bud formation and development in this
grou]^. The buds are not produced by "Stolons" as they
are in most bud-propagating ascidians, but each blasto-
zooid, as the bud-individuals are called, arises separately
and directly from its parent zooid. It forms at the anterior
end of the parent and in such a way as to be two-layered
from the very first, the layers being ectoderm or outer
laver^, and endoderm or inner layer. The bud when first

The Animal Organism and its Germ-Layers 51

separated from the parent is exceedingly simple, being an
almost perfect sphere. The layers are, at this stage, only
a single cell thick and are quite uniform throughout. The
endodermal layer, or "inner vesicle" as it is spoken of
technically, is separated from the ectoderm or "outer ves-
icle" by a wide space all around. Because of these simple
conditions the investigator is able to make out with great
certainty most of the events in the transformation of the
vesiculate stage into the completed organism. The first
differentiating step noticeable in the inner vesicle consists
of a somewhat elongated outpocketing of the wall of the
dorsal side of tlie vesicle. What occurs later in connection
with this outpocketing may be stated by quoting from the
original paper: "Simultaneously with the closing off from
the inner vesicle from before backward of the hypophyseal
duct, the ganglion becomes differentiated in the same order
from the cell mass that forms the last connection between
the duct and the vesicle." The "ganglion" is, it should
be stated, the beginning of the whole central nervous system
of these animals. My observations being a confirmation and
extension of those by other zoologists on other species, not-
ably by the older zoologists Giard and Kowalevsky, and in
the period of recent methods, by Hjort, there can be no
question that the nervous system arises in some gemmipar-
ously produced ascidians, from the inner germ-layer whereas
in individuals of the same sjjecies produced from eggs, the
nervous system arises as it does in the vast majority of
animals from the outer germ-layer.

The only point that has been or can be made against
this as an instance of complete transfer of the place of
origin of the nervous system from one germ-layer to another,
is that the "inner vesicle" of the bud is not in reality endo-
derm but ectoderm, this resulting from the manner of de-
velopment in the parent of the layer from which the inner
vesicle originates. There i§ considerable ground for this

52 The Unity of the Organism

interpretation of the inner vesicle so far as Botryllus is
concerned, but much ground against it for several other
species. Even though the Irishism that the endoderm of the
bud is not endoderm but ectoderm, that is, that the inner-
derm is really an outer-derm be accepted as true, the real
issue so far as this discussion is concerned remains unaf-
fected. Whatever the inner layer should be considered as
judged by its origin, judged by its developmental potency
its endodermal nature is beyond question, for nothing is
more certain than that it gives rise to the main part of the
alimentary system as, in accordance with the general rule,
it ought to. The kernel of the matter is that here is a case
in which both the digestive organ and the ner\^ous system
arise from the same germ-layer, which is contrary to the
almost universal rule. What that layer should be called
matters not, as we are now looking at the situation.

We can see, as intimated at the outset, the probable im-
mediate cause of this fundamental modification of the on-
togeny. Hjort was the first to dwell adequately on this
aspect of the subject. But since my own conclusions were
drawn before his memoir reached me and so were wholly in-
dependent of his, it will be permissible to present the ex-
planation in my own way. This I will do in the original
language slightly modified. The ectoderm of the ascidian
bud, even at its very beginning, is part and parcel of the
ectoderm of the parent, particularly in Goodsiria and Bot-
ryllus where, in the absence of a stolon, the budding region
is enveloped in the cellulose tunic characteristic of ail
tunicata. This is equivalent to saying that the ectodeiTn
of the bud is not, even at the very outset, an embryonic
structure at all. It is, on the contrary, a differentiated
organ whose function is, as in the parent, to secrete the
cellulose matrix of the outer tunic. In the performance of
this function, it would appear to be vigorously and con-
sistently active, for the matrix is large in quantity and prob-

The Ammal Organifim and its Germ-Layers 53

ably constantly renewed. This production may, as Hjort
liad well contended, be compared with the production of
horn, or still better, of cartilage matrix by the cells appro-
priate to these substances. So the ectoderm has a well-
established physiological role to play from the very earliest
stage in the career of the bud. Quite otherwise is it with
the endoderm. It is difficult to see how a structure could be
more favorabl}'^ circumstanced for retaining, so far as its
physiological relation to the organism as a whole is con-
cerned, an undifferentiated state than is the case with this
one. It is wholly protected from contact with the external
world by being enclosed in the ectodermic vesicle; further-
more, it has little or nothing to do with the preparation of
its own nutriment, since it is constantly and completely
bathed in the maternal blood. So why should not the pro-
duction of structures which in embryogenesis belong to the
ectoderm, be here transferred to the endoderm .^^ And so
it is.

This conclusion is the more justified when one considers
how differently circumstanced are the two layers in the
embryo. Here the incipient nervous system arises from
the ectodeiTn while the layer is in a strictly embryonic stage
and before the endoderm has freed itself from the rich store
of yolk material which is passed on to it from the egg. We
seem to have here an instance in nature where the later
functional requirements of the organism as such have run
counter to the way in which, through the operation of re-
moter hereditary influences alone, development would pro-
ceed; and the former have proved more powerful.

(b) Evidence From Bud Propagation in Bryozoa

Defiance of the germ-layer doctrine is by no means re-
stricted to the gemmiparous ascidians. In bud propagation
in bryozoa, a widely different group, departure from the

54 The Unity of the Organism

rule is no less certain and fundamental. The developmental
processes in these animals are somewhat more obscure at
several crucial points than in the ascidians, and there has
been proportionately more diversity of interpretation among
investigators. Nearly all, however, from H. Nitsche who
first pointed out the anomalies here presented, to the latest
students in this field, Calvet and Romer, agree to the extent
of recognizing that the layers of the buds in these animals
do not conform to the germ-layer scheme that prevails so
widely in ontogenesis starting from the ^gg.

A good summary of the view most commonly held by
specialists in this field is given by Harmer.* "There is
good reason for believing that in polyzoa the polypide-bud is
developed entirely from ectoderm and mesoderm. This bud is
a two-layered vesicle, attached to the inner side of the body-
wall. Its inner layer is derived from the ectoderm, which at
first projects into the body-cavity in the form of a solid
knob surrounded by mesoderm-cells. A cavity appears in
the inner, ectodermic mass, and the upper part of the
vesicle so developed becomes excessively thin, forming the
tentacle-sliciith, which is always in the condition of retrac-
tion. The lower part becomes thicker; its inner layer gives
rise to tlie lining of tlie alimentary canal, to the nervous
system, and to the outer epithelium of the tentacles, which
grow out into the tentacle sheath. The outer layer gives
rise to the mcsodermic structures, such as the muscles, con-
nective tissue, and generative organs." Although this de-
scription may not give a very clear picture to readers un-
acquainted witli the structure and development of the bry-
ozoa, the point of central importance to tliis discussion is
clear enough : The outer layer of the body wall gives rise
to the inner layer of the bud, and from tliis layer is pro-
duced the lining of the alimentary canal, and the entire
nervous system. No matter what the outer layer of the
body-wall and its continuation as inner layer of the undif-

The Animal Organism and its Germ-Layers 55

ferentiated bud be called, the germ-layer doctrine is set
at nauglit since one laj^er gives rise to both the digestive
epithelium and the nerve ganglion.

As a matter of fact, this statement falls short of reveal-
ing the full measure of confusion as regards germ-layers
wliich prevails in these animals, since one layer, the outer
of the body-wall, contributes to every essential part of the
polypide in some species. Thus Calvert shows that in Bug-
ula sahaiieri cells are set free into the body cavity from the
outer layer at the time that the knob of cells of that layer,
which is the foundation of the bud, makes its appearance,
and these freed cells assemble to produce, in part at least,
the layer on the surface of the knob usually called the meso-
derm of the bud. And this observation Romer has confirmed
"mit aller bestimmtheit" for another species, Aleyonidium
mytile. It seems that the entire polypide may be formed
from a single germ-layer, namely the ectoderm.

The reader should not fail to compare what is here set
forth about bryozoan budding with what we learned about
ascidian budding to the extent of noticing that whereas in the
ascidian we found the inner layer (no matter whether called
endoderm or by some other name) producing nearly the entire
zooid ; in the bryozoan the outer layer (no matter by what
name called) produces in some cases, nearly the entire poly-
pide.

If it be asked whether the principle invoked to explain
why the ectoderm of the ascidian bud takes so small a part
in producing the future animal (namely, that of greater
functional specialization and activity of the ectoderm than
of the endodoiTn at the place of origin of the bud,) be also
available for explaining the reverse order in layer con-
tribution to the bud-produced animal in the bryozoan, no
very satisfactory answer is forthcoming from the infor-
mation we now possess. Two facts may be adverted to, how-
ever, which suggest that the same principle is operative in

56 The Unity of the Organism

the two cases. In the first place, it may be reasonably
doubted whether the thin cuticular covering produced by the
outer layer of the body wall in the bryozoan involves as great
a degree of specialization either in nature of product or in
extent of activity as does the far more voluminous "test"
material produced by the ascidian ectoderm. In the second
place, the so-called mesodermal layer of the bryozoan body-
wall surely has no such direct and intimate connection with
the parent polypides, i.e. the other members of the colony,
as does the "cloison" or inner tube of the ascidian colony
from which the inner vesicle of the bud is produced. We may
consequently surmise that in the bryozoan as in the ascidian
the layer that is most available because of being least fully
occupied with activities pertaining to the parent organism
is most largely drawn upon in bud propagation. A kind
of balance between the functions of growth and maintenance
on the one hand, and propagation on the other, is struck in
each case although this implicates the germ-layers in op-
posite ways in two cases.

^'

The Animal Organism and its Germ-Layers 57

(c) Evidence from the Regeneration of the Lens of the

Amphibian Eye

The supremacy of the organism over its germ-layer is
shown in no way more strikingly than in facts brought to
light in some of the researches of late years on animal re-
generation. Perhaps the case at once the best established
and most discussed is that of the way the extirpated lens
of the eye is renewed in some amphibians. Referring to the
parts enumerated above as arising from each of the three
germ-layers in vertebrates, we note that the lens is assigned
to the ectodeiTn. To be a little more explicit, this member
originates from the outermost epithelial layer of the head
of the embryo. Hardly any point in vertebrate embryology
is easier to demonstrate than this. Experiments have
proved, however, that when a new lens is produced in a full
grown animal, to take the place of one that has been de-
stroyed, this does not arise as did the original from the
surface epithelium but from the edge of the iris, that is,
from a part of the eye itself. The discoverer, Collucci, did
not consider it to be out of accord with the genn-layer doc-
trine because the iris is the highly modified rim of the orig-
inal optic cup, which is derived from the cerebral vesicle,
which in its turn is derived from the ectoderm, so that in a
round-about way the iris is an ectoderaial product. The
fact remains, nevertheless, that the mode of origination of
the new lens is so radically different from that of the old
that to regard it as sufficiently dealt with when attention
is called to the fact that it conforms in a way to the genn-
layer doctrine is an impressive illustration of the evil effects
of subserviency to a theory — of the inhibiting effect of such
a mental attitude upon interest and observation. Later
investigators, notably G. Wolff, A. Fischel, and W. N.
Lewis, have shown how much more there is to the phenomena
of development and regeneration of the vertebrate eye than

58 The Unity of the Organism

the single matter of reference of the several parts to their
appropriate germ-layers. The work of these students car-
ries the subject into other fields, particularly those of re-
generation, and of formative stimulation.

The Germ-Layer Theory and the Germ-Plasm Theory

This discussion of the germ-layers will terminate with a
section on the part played by the layers in producing the sex-
cells where propagation is by the sexual method. This ter-
mination will also be the culmination in point of importance,
since it will lead as well into the examination, to be con-
tinued in other sections and chapters, of the results and
the general modes of reasoning of the Weismannian school of
speculation about heredity.

The manner of involvement of the layers in the specula-
tions of this school becomes apparent on a moment's reflec-
tion. As is widely known, Weismann and his adlierents
conceive a particular substance known as germ-plasm to
which all the phenomena of heredity are due, this being fun-
damentally different from and independent of the great mass
of substance called by them somatoplasm which makes up
tlie bodies of organisms. Not only is this germ-plasm quite
apart from the somatoplasm in a given individual plant or
animal, but it passes along from parent to offspring, gen-
eration after generation, wholly uncontaminated, as one may
say, by contact with the somatoplasm. This supposition of
a propagative stream or string has been elaborated into
what is known as the doctrine of the "continuity of the
germ-plasm." A point fundamental to the doctrine is that
not merely the germ-plasm may pass over in this way from
parent to offspring, or that so7ne portion of it always does
thus pass, but that all the germ-plasm the offspring ever has
comes from this source. Otherwise expressed, the doctrine
is tliat germ-plasm is never produced anew in a strict sense.

The Animal Organism and its Germ-Layers 59

Weismann is sufficiently explicit on this point. Not only
does he assume that germ-plasm cannot be produced by the
transformation of somatoplasm, but he holds it cannot be
produced in any other way. Touching the more special case
we read : "All these facts support the assumption that so-
matic idioplasm is never transformed into germ-plasm, and
this conclusion forms the basis of the theory of the compo-
sition of the germ-plasm as propounded here." ^

A fairly typical expression of the author's all-embracing
denial of new germ-plasm is the following: "The off-
spring owes its origin to a peculiar substance of extremely
complicated structure, viz.: the 'gcrni-phism.' This sub-
stance can never he formed anew; it can only grow, multiply,
and be transmitted from, one generation to another.'* ^ A
form of expression much used by Weismann particularly in
his later writings, which somewliat disguises though does
not surrender the main point, is that of "primary con-
stituents" of the germinal substance. Thus in his discus-
sion of the germ-plasm doctrine in his last extensive work,
The Evolution Theory, we find "I am forced to see in this
fact alone [that of metamorphosis in ontogeny] an invalida-
tion of all epigenetic theories of development, that is of all
theories which assume a germ-substance without primary
constituents, which can produce the complicated body solely
by varying step by step under the influence of external in-
fluences, both extra- and intra-somatic."*^ *

The Exact Mode of Involvement of the Germ-plasm Theory

in the Germ-Layer Theory

We return now to the immediate point, namely that of
the way the germ-plasm doctrine involves the genn-layers.

* While this is not the place to point out in detail the far-reaching
consequences of this assumed impossibility of new formation in or-
ganic evolution, much less to show the subtle fallacy which it involves,
the general subject is so important and will loom up so greatly in our
enterprise as a whole, that I would wish to get it well into the read-
er's attention even at this early stage of our progress.

60 The Unity of the Organism

Since it is the main office of the sex-cells to carry the sup-
posed germ-plasm, and since germ-plasm cannot be distin-
guished from somatoplasm by direct observation, and since
sex-cells are not present in the individual organism of most
species up to and including the layered stage of its life, the
question of exactly how and where the sex-cells arise will
be seen to involve the question of which of the layers they
arise in. The problem may be stated more explicitly as
follows : Where is the germ-plasm between the time when the
germ-cell which is the beginning of a new individual disap-
pears through division, and the appearance of new germ-
cells within that individual, as the first stage in the life of
an individual of the next generation? Or, stating the ques-
tion still more explicitly, by what means and by what route
does the assumed pre-existent germ-plasm get from its orig-
inal place in the sex-cell which produces a given individual
to the sex-cell produced by that individual?

Weismann'*s Studies on the Origin of Germ-Cells in Hydroids

Our purpose restricts our examination of the question
stated in this general form, to the particular question of
where and how (relative to the germ-layer) the sex-cells
arise in an individual. Since Weismann elaborated his solu-
tion of the problem largely on the basis of phenomena pre-
sented by the Hydromedusae, many of which phenomena
were brought to light by his own researches, we shall give
these animals the central place in our examination. In the
first place, the fact should be clearly understood that Weis-
mann has never contended that a direct observable continu-
ity between the parent sex-cell and the sex-cells of the off-
spring occurs in this group of animals. On the contrary,
he fully recognizes, as do all students of these animals who
have occupied themselves with this particular point, that
a wide gap separates the parental from the filial sex-cells.

The Animal Organism a7id its Germ-Layers 61

The very earliest recognizable sex-cells occur in the one or
the other of the two body layers ; that is, in the ectoderm
or the endodenn of the fully developed animal. Since Weis-
mann's theory denies the possibility of the origin of the
sex-cells, or at least the essential part of these, the germ-
plasm, from somatoplasm, his theory of sex-cell production
in such animals as the hydroids must contain two quite
distinct parts : one as to the route by which the germ-plasm
travels from parental to filial sex-cell, and the other as to
the force or forces by whicli the journey is accomplished.

The first part of the theory starts from the indubitable
facts that in those hydromedus.x' having a free-swimming
medusa, or jelly fish, the sex-cells are borne by this and not
by the polyp; that these cells do not as a rule arise in the
medusa itself, but somewhere in the colony of polyps, from
which location they migrate (in some cases for considerable
distances) to the buds whicli later develop into medusae; and
that in the majority of species which have been examined
with reference to the point, the mature sex-cells are found
in the ectoderm and not in the endodenn. On the basis of
these facts Weismann thought out a very elaborate and in-
genious theory by means of which through various assump-
tions about the evolutionary history of the hydromedusa?,
he was able to make the facts seem not only to harmonize
with, but to support positively the doctrine of the con-
tinuity of the germ-plasm. Into that part of the theory
which concerns the phylogenetic relation of the medusoid to
the polypoid forms of the group, we need not. go further
than to say that through his speculations on this point he
was able to provide a Marschronte or germinal highway or
germ track from the parent sex-cell to the filial sex-cell. The
question of where this Marschronte runs, with reference to
the germ-layers is what immediately concerns us.

According to the theory, the germ-plasm of the parental
sex-cells passes first into certain cells of the ectoderm of

62 ^ The Unity of the Organism

the polyp-generation from which place those cells make their
journey to the ectoderm of the medusa, usually to some
portion of it connected with the manubrium or digestive
part of the animal. But — and here we come to the real
point of the present discussion — since sex-cells are found by
actual observation in the endoderm, in several genera and
species, the theory is that the Marschroute lies first in the
ectoderm, then passes over into the endoderm and returns
later to the final goal of the sex-cells in the manubrial ec-
toderm. The ectoderm therefore is the home by natural-
ization, so to say, of the germ-plasm in these animals ; it is
originally planted there from the parental egg and finally
matured there. As will be seen from what has previously
been said, the kernel of the theory is to account for the
positions and movements of the sex-cells in accordance with
the supposition that their most essential part, their genri-
plasm, cannot be formed anew from somatoplasm of any
sort either entodcrmal or ectodermal, but must come over
in direct continuity from the germ-plasm of the parental
egg. The reason why the theory is so insistent on ascrib-
ing the sex-cells to the ectoderai is that it supposes that
originally in the evolutional history of the group,, the germ-
plasm destined for the next generation of sex-cells was
lodged in the ectoderm, and that this predestined it to that
layer for all time.

Inconclusive ness of Weismanns Results Shown hy Goette

and Others

We have now to inquire how it has fared in later research
with the numerous subsidiary hypotheses which enter into
this complex tlieory of germ-plasm behavior in these organ-
isms. Alexander Goette has lately gone over almost the
entire grounds covered by Weismann in tlio monograph al-
ready mentioned, and his i*esults and general conclusions

The Animal Organism and its Germ-Layers 63

are interesting in the liighest degree. It would be impossible,
even were it desirable, to review the memoir exhaustively.
As to the most general aspect of it, it will suffice to say that
Goette takes issue with nearly every one of Weismann's most
important conceptions. The liypothesis that the gonophores
are in all cases degenerate medusae; the hypothesis of Mar-
scliroute (of hard and fast germ tracks); the hypothesis
of entirely independent activity of the sex-cells in migration
supported by the suggestion that the cells migrate by virtue
of a "homing instinct" something like that supposed by
some naturalists to be possessed by migratory birds ; and
finally and most relevant to the present discussion, the hy-
pothesis which denies the actual origin of the germ cells in
the endodenn : all these hypotheses and others which could
be mentioned, Goette holds to be either in positive opposition
to the observed facts or not necessitated by them.

It would be contended on the Weismannian mode of theor-
izing that since the issue is mainh^ one of interpreting facts,
and not of what the facts are, Goette's views are entitled
to no more weight than are Weismann's, and so do not con-
stitute a disproof of the hypotheses in question. As this con-
tention comes very near to the center of Weissmann's logical
procedure, we must look at it attentively. Assuming that
Weismann and Goette are equally endowed by nature and by
training as observational biologists (and I have no doubt
the great majority of unbiased zoologists who know the
work of the two men would allow this), it must be granted
that Goette as pitted against Weismann does not constitute
a disproof of the latter's hypotheses. But does this admis-
sion leave these hypotheses just where they were before
Goette's attack upon them? By no means. We may state
the case this way : Weismann observes a long series of facts
concerning the structure and development of a particular
group of animals, and on the basis of these and in the
interest of a theory of still more general scope, and of pre-

64 TJie Unity of the Organism

vious formulations, sets up a number of hypotheses. That
these are fully proved is not contended even by Weismann
himself: they are only given a good degree of plausibility
or probability. Then comes another investigator of equal
competency who goes over essentially the same ground and
reaches essentially the same factual results, but who does not
believe the hypotheses propounded by the first investigator
are supported by the facts. What can a third person legiti-
mately see in the total situation other than that whatever
probability was given the hypotheses by the one investigator
has been taken away from them by the other investigator?
So far as we have yet gone with our examination we are, I
think, compelled to recognize that as regards interpretation
of structure and reproduction in the hydromedusae, Goette's
work leaves the matter just where it was before Weismann
propounded his hypothesis. But we have not concluded the
inspection ; we have only considered Goette's w^ork in its re-
futational or destructive aspect. Whatever of positive re-
sults both as to observation and hypothesis he has to set
over against Weismann's must now be briefly considered.
And here we return to the matter in hand in this section,
that, namely, of the relation of the sex-cells to the germ-
layers.

Goette believes he has proved incontestably that the sex-
cells do arise in the endodervi in some species, so that Weis-
mann's assertion that in this group they always arise in the
ectodcnn is wrong. But of far greater importance, Goette
shows that not only the endodcrmal but also the ectodeiTnal
origin of the sex-cells is such as not to give the least warrant
for the hypothesis that any part of the cell (the supposed
germplasm being of course aimed at) does not arise by trans-
formation of the material of the layer in which they first
appear. And in this it seems to me he has made his case.
His description accompanied by numerous drawings of the
sex-cells in Corydendrium parasiticum, may be instanced

The Animal Organism and its Germ-Layers Q5

as a particularly clear case of the genuine transformation of
cndoderm cells into sex-cells. To be still more explicit, in
liis figure (115 plate V,) is shown a sex-cell so slightly differ-
ent from the neighboring cndoderm cells, and so related to
the surrounding cells, that no one would hesitate to conclude
that it had very recently arisen by division of one of the
cndoderm cells unless influenced by considerations other than
the evidence actually before his eyes. Exactly the same
conditions, he says, are observable in Clava, Sertularia, and
Sertularella; and he then remarks: "From these observ'^ations
it becomes unfair to assume that in other cases where germ
cells are found in the endoderm that they have wandered
from the ectoderm. Proof of tliis must be absolute." ^ The
full force of this remark is seen only when it is taken in
connection with Weismann's own statements about the sex-
cells of Corydendrium parasiticwm. He saw here no less
positively than did Goette, very young stages of the cells in
the endoderm ; but since, he says, he could not find the ab-
solutely first stages "the possibility of the ectodermal ori-
gin of the sex-cells is not excluded." ^ In other words, the
absence of absolute proof of the endodermal origin of the
cells is used to support the a priori conclusion that they
arise in the ectoderm ! So far as the observational evidence
in this specific case goes, it strongly supports, as Weismann
himself grants, the conclusion that the reproductive cells
arise in the endoderm, but since the evidence falls a little
short of finality it may be cast aside wholly in favor of
purely theoretical grounds for supposing the origin to be
elsewhere! Against this method of reasoning Goette
strongly protests, and every biologist who genuinely be-
lieves that speculative proof must yield to observational
proof when the two come into conflict, will say amen. And
when once one sees the extent to which Weismann's whole
system rests upon this method, and sees at the same time
how widely influential the system is, he will recognize that

66 The Unity of the Organism

it is hardly possible to overestimate the importance of cor-
recting the method and neutralising the evil it has wrought.

Weismanns Erroneous Conclusions Concerning the Origin
of Sex-Cells in Hydroids as an Example of the
Effect on the Observing Powers of the Germ-
Plasm Type of Speculation.

A striking example of the effect of this system of specula-
tion on the observing and reasoning faculties is afforded by
Weismann's way of viewing the part played by the genn-
layers in bud propagation in young animals. We might
have presented the case when we were dealing with budding
in ascidians and bryozoans, but as it implicates germ-cells
and germ-plasm more intimately than we were prepared for
at that time we speak of it here.

As pointed out above, Weismann's general interpretation
of the sex-cells in the hydromedusa^ led him to conceive that
the germ-plasm is lodged in the ectoderm in these animals.
This being so, he naturally concluded that his imaginary
bound C^gebu/nden*'), or unalterable, or accessory germ-
plasm set aside for bud propagation ("blastogenic germ-
plasm") must also be confined to the ectoderm. But ac-
cording to the various researches, both endoderm and ecto-
derm participate, as a rule, in giving origin to the bud.
What was to be done about this? Notice carefully what,
according to the system, would be a sufficient confirmation
of the theoretical view that buds really arise solely from
the ectoderm: To find one or a few instances in which the
buds do either certainly or probably begin in that layer, to
assume this to be the phylogenetically primitive condition,
and then to point out that in cases in which the two layers
undoubtedly enter into the bud in the earliest stage, the
"possibility is not excluded" that latent invisible germ-plasm
is present in the ectoderm, becomes active at the place where

The Animal Organism and its Germ-Layers 67

a bud is to form, iiiigratcs into the ciidoderin, and so ex-
plains the participation of the endoderni in bud production.

Goette's conclusions as to the actual endodernial origin
of sex-cells in the h^^droids are not unsupported by other
workers. Thus Tichoniiroff holds tiiat the sperm cells of
Eudendr'iurn aurentiwm arise in this layer, and C. W. Har-
gitt, who has devoted much time to the question, is unc^uali-
fied in his statements. He writes in a sunnnary presentation
of his results : "It may be said that while in Eudendrium
ramoswm and E. tenue the ova arise strictly in the endo-
derm, and never at any time find their way into the ectoderm,
in the species racemosum and disjxir these products are
found abundantly in both tissues." ^^ So the observations
seem conclusive that taking the group of hydromedusae as
a whole, the sex-cells arise in the ectoderm in some species
and in the endoderni in other species, and that this origina-
tion is by a transformation of substance in both cases from
what it was originally into that of the reproductive elements.
Indeed the power of the propagative function of the organ-
ism to start indifFerentl}' with either ectodermal or endo-
dermal material and reach the same end as seen in different
genera of the hydi^omedusa?, seems in some cases to extend
to different species of the same genus. "If one holds rigor-
ously to the facts," writes Goette, "he must in spite of all
hold to it as most probable that the Reims tcitte in different
species of End end riant, perhaps indeed in the same spe-
cies, changes." ^^

Finally, and as a cap-sheaf to the arguments here pre-
sented in favor of the view that sex-cells do arise genuinely
anew in each individual in the hydromedusse, it remains to be
shown that Weismann himself was really in accord with
Goette on this point when he wrote the monograph on the
origin of the sex-cells ; and that only later under the impul-
sion of his speculations about genn-plasm did he come to
repudiate this view. On page 284 of the monograph we find

68 The Unity of the Organism

the following: "After all this, there can be no doubt that the
germ cells may reach their differentiation and separation
from somatic cells only when the germ-layers have long since
been formed, and it is impossible to accept as a general law
the view of Xus.sbaum that sex cells are 'absolutely indepen-
dent of the germ layers.' So far as we can now see, the sex-
cells always arise in the hydroids from elements of one of the
germ-layers and they are not merely inclusions in a germ-
Iryqi' but are derivatives, are division products of it." ^^
Stripj^ed of all so})histry, how is it ])ossible to avoid seeing
that we have before us a clear case in which Weismann can
defend his doctrine of heredity at one of its most critical
points only })y making purely speculative considerations
supplant observational evidence which he himself produced
at an earlier period in his career?

The conception of an "hereditary substance" distinct
from a non-hereditary substance, by whatever name called,
and continuous from parent to offspring is contrary to the
observed facts of sexual reproduction in the hydromedus^e
as established by Weismann himself and by other and later
biologists of unquestioned competency and trustworthiness.
To this conclusion we are forced by an examination of the
available knowledge of the sex-cells in their relation to the
germ-layers in this group of organisms.

The Stronglij Oryanismal Implications, of Gocttc's Conclu-
sions on the Origin and Migration of Germ-
Cells in Hydroids

With this conclusion we return to the examination of the
constructive as contrasted with the destructive results of
Goette's research. We have sliown the most specific and im-
mediate of these as viewed from the standpoint of this sec-
tion on the organism and its germ-layers, that, namely,

The Amm(d Organism 4rid its Germ-Layers 60

wherein lie proves tlie actual origin of the sex-cells from
the endoderm. The only other positive result which I will
touch upon is that concerning the route and cause of
migration of the sex-cells from their place of origin to their
place of maturing. Goette denies that they have any single
road which is the same for all species, as contended by
Weismann. He affirms on the contrary, that at least four
paths are demonstrable, namely, the gastric endoderm; the
bases of the pouches of the radial canal ; the spadix ; and the
ectoderm of the manubrium. The kernel of Goette's con-
clusion on this subject, as opposed to Weismann's is, as I
understand, that the sex-cells arise widely scattered in the
parts and tissues of the polypoid colony, and that the de-
velopment of the gonads or sex glands consists in large part
in the drawing together or concentration of these dissemi-
nated elements, in some cases into buds that are to become
medusae proper, and in other cases where the medusoid is
wholly absent, into the gonophores or brood-sacs which are
outgrowths on the polyps. The diversity of the place of
origin precludes the possibility of any single "germ track."

Again Goette does not believe, as Weismann does, that
the journeyings of the sex-cells are due wholly to their own
independent activity , and considers the comparison of their
movements with those of migratory birds, and the ascrip-
tion to them of an innate instinct, to be entirely fanciful.
He holds, on the contrary, that these cells are largely car-
ried along passively by forces which originate in the sur-
rounding tissues and structures. His observations on the
cells of Podocoryne have, he says, been particularly con-
vincing that the wanderings are largely passive, and that
even where there is intrinsic movement this is indeterminate
as to direction, so that the final goal of the cells is in every
case determined chiefly by influences which lie outside the
cells themselves.

What the outside force is which Goette conceives to pro-

70 The Unity of the Organism

duce and direct the movements, we will hear him state in his
own words. It is "a result of the directive activity of the
definite and always similar developmental processes, . . .
therefore of those conditions which determine not only the
form of a body part, or organ, but also the transportation
and definitive emplacement of the separate particles. I re-
tain for this the expression 'form-conditions' used by me
several years ago."^^ Obviously this statement by Goette
carries us far beyond the bounds of germ-layers or even of
sex-cells and hereditary substance.

To the numerous biologists who would refuse to accept
Goette's "directing activity of the developmental process"
and his "Form-conditions" as an explanation of the mi-
gration of the sex-cells in tlie hydromedusse, because they
are vague and "unanalysed" conceptions, I put the question :
Are Weismann's conceptions of a wholly independent power
of movement possessed by the cells, and a deteniiination of
the route followed by them as an innate instinct of their an-
cestral home possessed by the cells, less vague and more
satisfactory because of the results of such an "analysis"?
Let it be granted for a moment that the cells perforai their
journeys by activities wholly their own, that they are com-
petent both to travel and to reach the end proper to them.
What then about the elements which enter into their make-
up, for surely no one would contend for a moment that they
are without elements.^ Shall we conceive that in moving they
do so by making use of their elements or parts in such fash-
ion as may be necessary to enable them to accomplish their
journeys? Or sliall we deny to the cells as such the power
of using their parts, but conceive that the parts are the
real seat of power — that in reality they move the cells instead
of being moved by the cells? If we accept the latter alter-
native, as in consistency witli tlie elementalist standpoint we
should have to, we shall be committed to either a never-
ending though ever-vanishing senes of biological elements.

The Animal Organism and its Germ-Layers 71

or to ultimate chemical elements endowed with, homing in-
stincts and the rest. Surely if either of these sub-alterna-
tives be accepted the analysis which goes no farther than
that of ascribing to the sex-cells power and instinct suffi-
cient to enable them to do what they do, would have gone
but a short way on its course and ought not to make any
pretence of being a complete explanation of the phenomena.
On the other hand, if we conceive that the sex-cells move
through the agency of their elements and are not merely
moved by means of these elements, why not as well allow that
the developing organism as such may move its cells to meet
its needs? As a purely logical matter there would be no
more hesitancy in admitting that the organism moves its
parts than in contending that the cell moves its parts, for
the difficulty of conceiving how the thing is done is no greater
in the one case than in the other. The only reason why the
conception that the cells migrate wholly by their own pow-
ers seems less vague, that is more analyzed, than the concep-
tion that the cells are moved by the growing organism, is
that in the first case a whole set of inevitable collateral phe-
nomena, that is those pertaining to the parts 'of the cells
themselves, is unconsciously excluded from the view. In
other words, the satisfaction felt by analysis of this sort
is an entirely spurious and illegitimate satisfaction begot-
ten of the fact that the analysis is false. It is a process
of searching for the factors involved in the complex of
phenomena under contemplation, but ignoring all excepting
a few of these factors. And this criticism of Weismann's
attempt to explain fully the migration of the sex-cells holds
for the attempt to explain on elementalist principles any
biological phenomena whatever.

I remarked above that as a "purely logical matter" there
is no more ground for refusing to believe the organism directs
the movements of the sex-cells than for refusinir to believe
the cells direct their own movements. It will not do to let

72 The Unity of the Organism

this remark go even in a tentative discussion of this vastly
important subject. If it is merely a question of equality
of claim upon belief as between the two conceptions so far
as logic is concerned, what is to determine the choice? Why
not accept the elemental as well as the organismal way of
interpreting the case if logically its claims be equal to that
of the latter? Because, I answer with emphasis, the observa-
tional evidence is stronger in favor of the organismal inter-
pretation. That is the sole legitimate ground on which to
rest the decision. Assuming, as we do, that Weismann and
Goette are equally competent and trustworthy investigators,
and basing the decision for the present on their results alone,
we are bound to recognize that Goette has brought forAvard
much more observational evidence that the migration of the
sex-cells is largely though not wholly passive than Weis-
mann has that it is wholly active.

Remarks on the Relation of Germ-Cells to Germ-Layers and

to the Organism Generally

Before taking leave of the concrete objects, germ-layers
and germ-cells, I speak of one aspect of the general results
of our examination which may escape the reader unless his
attention is specially directed to the matter. In all those
animals in which the sex-cells do not appear until the lay-
ered stage of the embryo is reached, and in which these cells
arise by a genuine transformation of cells of the layer, as
they do in hydromedusse, the layers are gemiinal in a very
fundamental sense, for it is in them that the transformations
begin which issue in the completed tissues and organs of all
sorts, the sexual tissues and organs with the rest. Viewed in
this light the germ-layers have, on the whole, gained rather
than lost in importance and interest, for while we are led
to deny the rigorous specificity to each particular layer as
to what may or may not arise from it that often constituted

The Animal Organism and its Germ-Lazjers 75

a part of the germ-layer theory, it is a great gain to have
perceived clearly that it is in the layered stage of the in-
dividual's life in many species that the next generation of
individuals takes its rise. However, it does not by any
means follow that because the sex-cells are born, as one
might say, at this early time in the life of the parent, they
are fully exem})t from parental influence during all the per-
iod intervening between the layered stage of the parent and
its stage of sexual maturity, that is, of final separation and
extrusion of the sex-cells.

It seems to me the fact that the sex-cells of even some
vertebrates are found at an early stage of embryonal life
embedded in one or another of the germ-layers at points far
removed from where the definitive germ glands will later ap-
pear, may signify just such influence. In other words, it
may be the meaning of the "precocious segregation," as it is
called, of germ-cells ought to be taken along with their wide
dissemination in the embryo, and interpreted as speaking
against and not for the fundamental isolation of the germ-
plasm.

The distribution of sex-cells in the early embryos of ver-
tebrates has been studied by several zoologists, among them
being C. H. Eigenmann and B. M. Allen. Allen's investiga-
tions are specially important because of their wide com-
parative scope. In The Origin of the Sex-Cells of Amia and
Lepidosteus he gives a set of useful diagrammatical com-
parative drawings showing the mode of origin of the sex-
cells from the endoderm of a reptile (Chrtjsomys), an am-
])hibian (Frog), and two fishes (Amia and Lepidosteus), but
reaffirms in his discussion the result that the cells arise in
the mesoderm in the tailed amphibians.

74 The Unity of the Organism

The Relatio7i of Ideas and Observations as Exemplified in
the Discussions of This Chapter

I would have this discussion stand as one example of the
general method of interpretation which underlies our whole
undertaking: while interpretation of biological phenomena
is wholly impossible without ideas, some of which take the
form of hypotheses and theories, equally true is it that
hypothesis and theory are wholly dependent upon observa-
tion for validity. To this every biologist in whatever field
of research and of whatever manner of thinking, would as-
sent. But I go farther and assert that no hypothesis is
proved, nor can be elevated to the rank of a general theory
or doctrine until it is brought into acdord with all relevant
and fully verified observational knowledge. To this no ele-
mentalist assents in practice even though he may in words.
Measured by this standard our final constructive discussion
will reveal the fact that such conceptions as those of Weis-
mann's germ-plasm and DeVries' pangens are not legitimate
scientific theories at all. They are not because they can be
maintained only by positively refusing to admit as evidence
many of the demonstrable relevant obsei^^ational facts.

REFERENCE INDEX

1. McMurrich 79 8. Goette 63

2. Minot 250 9. Weismann ('83) 42

3. Ritter ('96) 183 10. Hai-gitt 24^

4. Harmer 514 11. Goette 63

5. Weismann ('12) 190 12. Weismann ('83) 284

6. Weismann ('12) xiii 13. Goette 301

7. Weismann ('04) 400

Chapter IV

THE ORGANISM AND ITS CHEMISTRY

Standpomt of the Discussion that of the Evolutionary

Naturalist

I3HYSIOLOGISTS and biochemists are not forced into
^ contact with questions of organic evolution to any such
extent as are botanists and zoologists. Occupied as they
are in any particular investigation with relatively restricted
aspects of one or a few organisms, such matters as geogra-
phic distribution, geologic succession, abundance and variety
of individuals and species, adaptation, and so on, come to
their attention very little or not at all. But these are
exactly the problems with which the naturalist is occupied,
and they are at the same time the very building stones of
the evolution theory. This difference in interests and occu-
pations doubtless accounts for the fact that the great
evolutionists of history have been, without exception, natu-
ralists primarily. The three names that stand out with
mountain like conspicuousness among those who in modem
times have made the idea of evolution a household posses-
sion, Lamarck, Darwin, and Wallace, sufficiently illustrate
the point. These men were each botanist and zoologist in
almost equal degree and in the strictest sense. Their work
began out of doors with the vast riches of living plants
and animals, and the impetus from this source dominated all
they did.

In the highly subdivided and specialized biological realm
of to-day, those who are trained in either botany or zoology

75

'76 The Unity of the Organism

or in both, are perforce the ones who think most in terms
of the doctrine of evolution, and whose undertakings are
most guided and fashioned by evolutionary conceptions :
How and where and under what influences did these organ-
isms, these organs and tissues have their beginnings and
undergo development? So it happens that when a zoologist,
for example, is confronted with the vast array of chemical
compounds which his co-workers in the chemical laboratories
have made known, he is bound to extend to them his usual
string of queries. No matter how much information he is
given about the molecular construction, the solubility, the
reactions, the methods of laborator^^ production, of organic
compounds, he can be in no wise satisfied until he has been
told something about their original source, their way of get-
ting into existence, not only in the individual organisms but
also in the race. Many physiologists on the other hand, and
also it must be confessed, a considerable number of modern
botanists and zoologists, are very little concerned Avith such
questions. In fact it seems as though the evolution doctrine
had not made the slightest impression on many biologists
animated by the chemico-physiological spirit, so far as cjon-
cerns their attitude toward their special problems. These
students appear to "take" the substances they deal with as
things without beginnings, as eternally existent, or as com-
ing into being "by free grace," in some such way as pre-
Darwinian naturalists "took" their species. We had oc-
casion to refer at some length to a similar un-evolutionary
character of elementalist biology in a preceding chapter.

The question of how far such an attitude is due to the
fact that physics is preeminently not an evolutionary science
is one of great interest, both practical and theoretical. The
very basal conception of modern physics, that of Matter and
Energy as the only real things (as in the quotation from
Watson : ". . . in the pliysical universe there are only two
classes of things ; to these the names Matter and Energy are

The Organism and its Chemistry 77

given."), or at least as the most real of all things in nature,
seems to carry with it an element of liostility to evolution,
to the conception of origination by transformation and
growtli. But tliis is no place to deal with the vast problems
thus intimated; sufficient to have mentioned the matter for
the sake of a background for the discussion now before us.
Our standpoint in this chapter on the organism and its
chemical substances is to be that of the evolutionary natu-
ralist. We are to j)ush our studies of the structure and
function (the morphology and ])hysiology) of organisms
into chemical foundations, and are then to inquire concern-
ing the mode and place of origin of the foundational sub-
stances, and also concerning the adaptation of these to the
needs of the organism. In other words, we are to look upon
the chemical elements and compounds entering into the make
up of organisms in the same way that w'e look upon the cells,
tissues, and organs which enter into their composition. In
fidelity to the best traditions and practices of natural his-
tory for the last century at least, the evolutional and adap-
tational aspects of our inquiry will presuppose much careful
description, definition, comparison and classification of these
substances.

Touching the descriptions presupposed, the following
qualifying considerations should always be kept in mind :
The naturalist is entirely unable to "go behind the returns"
of the chemist in estimating the accuracy and fulness of the
descriptions. He must accept what is furnished him from
the chemical laboratories, exercising no critical judgment
beyond that always requisite in tlie choice of authorities
where one is obliged to go into fields not his own for facts.
From this consideration very little actual description of
organic chemical substances will be given in our discussion.
We shall in general restrict ourselves to substances the
existence and main attributes of which seem to be no longer
in question among chemists themselves.

78 The Unitij of the Organism

The second and more fundamental qualifying considera-
tion is that, knowing as he does something of the methods
by which the chemist gets at the chemical substances of or-
ganisms in order to describe them, the naturalist is unable
to suppose the compounds and processes described by his
chemical coworkers to be anything better than more or less
distant approaches to the substances that actually exist,
and the processes that actually go on in the organism as the
naturalist is primarily concerned with it ; that is, as living
normally. The naturalist accepts not only without hesita-
tion but with eagerness and gratitude the chemist's report
on what he is able to get out of the organism. That these
reports come near setting forth what the organism actually
is, the naturalist is bound to recognize cannot be the case.

This reservation the naturalist feels the more justified in
making by noticing that there are physiologists of unques-
tioned standing who hold views which amount really to the
same thing. Thus the distinction between living and dead
albumen (Eiweiss), first sharply drawn by Pfliiger (Ueber
die physiologische Verbrennung in den lebendigen Organis-
men, Archiv fiir die gesamten Physiologic, Bd. 10, 1875)
and since recognized by other investigators hardly less
eminent is manifestly of the same import. ( See, for example,
j\Iax Verworn, p. 596, Allegemeine Physiologic, sechstc Aufl.)

The Organism as a Chemical Laboratory

Immediately the fertilized Qg^r begins to develop, chemical
substances are produced within it. Among the higher ani-
mals the hen's ^gg has been the most studied in this as in
many other aspects. "Neither nucleo-proteins nor pentoses
are present in the fresh (^gg-, and purine bases are present
only in very small amounts. The fact that during develop-
ment these substances rapidly increase in amount indicates
therefore that a synthesis of nucleo-protein from the reserve

The Organism and its Chemistry 79

material of the egg (proteins and pliospliorized fats) takes
place during development." ^ This statement by Marshall
on the authority of Kossel and of Mendel and Leavenworth,
may be taken as typifying a wide range of present-day
knowledge of the synthesizing power of the growing embryo.
Because of its inaccessibility the mammalian ovum has
been but little studied chemically. However from what is
known of the chemistry of the eggs and embryos of other
animals, particularly' of the chick, we are entirely warranted
in asserting that a full grown man, for example, contains an
enormous number of chemical substances which are not pres-
ent in the egg from which he developed. The chondrin of
cartilage, the paraglobulin of blood serum, the haemoglobin
of red blood corpuscles, the nwosin of striated muscles, the
various enzymes of the digestive glands, the neurokeratin
and protagon of the central nei'^'ous system, and innumer-
able other compounds more or less specific for particular
organs and tissues, come into existence in the course of
development. And this production of new substances con-
tinues, with many organisms at least, up to the very end
of the developmental series, even to the end of the lives of
the organisms. This is well illustrated by the more or less
distinctive oils, essences, acids, etc. occurring in ripe fruit.
And few facts bring home more forcibly the subtlety and
intricacy of the organism as a producer of chemical sub-
stances than do odors and flavors of flowers and fruits.
The products of the organism's operations as a manufac-
turing chemist are seen to be of two rather shai'ply dis-
tinguishable sorts when the total chemical make-up of the
developed organism is compared with the total make-up (oi
the germ-cells. First there is a considerable number of sub-
stances common to adult and germ. Thus both tail and
head of the spermatozoa of various fishes were shown by
the well known researches of Miescher and Kossel to contain
lecithin and cholestrin, both substances occurring also in a

80 The Unity of the Organism

large number of adult tissues, as the blood, brain and nerves.
The nucleic acid of the spermatozoa is said by Cramer to be
very similar to that of the somatic cells and "probably iden-
tical with the nucleic acid prepared from the thymus." "
But more interesting- than the substances of identical struc-
ture which may be extracted from both germ and adult are
the series of mixtures of phosphorized fats more complex
than lecithin, which are present in the yolk of various eggs,
some portions of which disappear as development progresses,
seemingly being consumed as a part of the energy of develop-
ment.^ Other portions are transformed (?) substances of
the same general nature in the tissues.^

So far then as concerns substances that are identical in
germ-cells and cell^ of the mature organism, development
consists merely or primarily in increasing their quantity.
Such substances may consequently be looked upon as an
actual realization of the doctrine of preformation which
formerly played so great a role in speculative embryology.
But the number of substances remaining exactly the same
from the earliest to the latest stages of development is very
small in comparison ^vith the number wholly or partly new
in the later stages. So that from the chemical standpoint
development is for the most part strictly epigenetic; that
is, it is a process not merely of increasing the mass, the
quantity, of what previously existed, but as well of coming
into existence of new kinds of substance. It is a qualitative
as well as a quantitative, process. The living, growing or-
ganism is creative in the strictest sense and that on a vast
scale. "The lout," writes Oliver Wendell Holmes, "who lies
stretched on the tavern bench, with just mental activity
enough to keep his pipe from going out, is the unconscious
tenant of a laboratory where such combinations are con-
stantly being made as never Wohler or Berthelot could put
together : where such fabrics are woven, such colors dyed,
such a commerce carried on Avith the elements and forces

The Organism and its Chemistry 81

of the outer universe, that the industries of all the factories
and trading estahlishnients in the world are mere indolence
and awkwardness and unproductiveness compared with the
miraculous activities of which his lazy bulk is the unheeding
center." ^

The scientist cannot afford to let the literary quality of
this paragraph obscure the truth it expresses. The ac-
complishments of organic chemistry in producing substances
in the laboratory which it was formerly supposed could be
produced onl}' by the living organism, have been so brilliant
as to obscure somewhat the significance of the ibict that these
artificial products are imitations: Nature made them before
man did, and for the ends they originally answered they are
still produced only as they formerly were, by the organism
itself.

The fact that the chemist is able to produce what the
organism produces in no way derogates from the significance
of the fact that the organism does produce them. One can
hardly see the import of the point here made until he reflects
on the difference between the chemist's ability to produce
in his laboratory compounds which are the same as the dis-
carded end-products of the living organism's operations, or
wliich can be extracted from the dead body of the organism,
and the elaboration of substances which constitute the es-
sential parts of the organism while it is still living and work-
ing. The problem can be put in concrete form by noting
that the chemist produces certain substances in his labora-
tory by the activities of his brain and hands, and certain
other substances in his body by the activities of his digestive
organs, glands, muscles, brain and so on ; and then asking
how far those produced by the first means can be the same
as those produced by the second. May the operations of
the first kind be fully substituted for those of the second
kind? May the brain and the hands with the appropriate
laboratory apparatus ever be able to do the aictual ^york

82 The Unity of the Organism

of the liver for example, or the blood, or the testes or the
ovary? The views prevailing to-day among physiologists
and biochemists would favor an affirmative answer to these
questions. In order to maintain some show of modesty the
contention would be that while the chemist is not yet able
to make these substances, there is no reason for supposing
he will not be later. At any rate, so the view is, except for
practical manipulative difficulties the substitutions might
be made.

And it should be pointed out that thinking of the organ-
ism as a chemical laboratory, as suggested above, is not a
mere literary fancy somewhat tinctured with science. By
modifying the conception to the extent of making cells and
tissues instead of an individual man the laboratory, it has
figured considerably in recent biochemistry. According to
Bayliss,^ Hofmeister definitely formulated the idea in 1901,
so far as the cell is concerned, and it "is rapidly gaining
ground."

About the clearest statement of it I have come upon was-
made in 1913 by F. G. Hopkins. This biochemist illustrates
the synthesizing activities of the organism by several spe-
cific examples, the last of which concerns nicotinic acid.
When this "is fed to animals, it is excreted as trigonellin, a
known vegetable base. This conversion involves methyla-
tion, and is of striking character as an instance of the
artificially induced production of a plant alkaloid in the
animal body." ^ * At the conclusion of tlie illustrations
Hopkins says : "The known facts have, one feels, an aca-
demic character in the view of the physiologist and even in
that of the pharmacologist, to whom we owe most of our
knowledge about them. But, in my opinion, the chemical
response of the tissues to the chemical stimulus of foreign

* Looking upon the production here instanced as "artificially induced"
is worth noticing, since it clearly suggests that the conception of the
organism as "chemical lal)oratory" im})lies not only the laboratory luit
the chemist who works in it.

TJie Organism and its Chemistry 83

substances of simple constitution is of profound biological
significance. Apart from its biological bearings as the sim-
plest type of immunity reaction, it throws vivid light, and
its further study must throw fresh light, on the potentiali-
ties of the tissue laboratories." ^

Different Organisms as Different Chemical Laboratories

But this glance in the exclusively descriptive way, at the
chemical foundations of the organism in the various stages
of its life, in no wise satisfies the modern natural history
standpoint. As indicated in the remarks introductory to
this chapter, that standpoint is comparative as essentially
as it is descriptive. The moment this methodological plank
in the natural historian's platform is reached, the insuffi-
ciency is seen of the conclusion that some individual organ-
isms are manufacturing chemists or even that all are.
Taken thus the result is altogether too general. The most
cursory observation leads to the recognition that if every
organism be a producer of chemical substances, not all
organisms can be producers of the same substances, and
that the extent and nature of the diversity of products
w^ould be interesting and important from both scientific and
practical considerations. Now the comparative method in
zoology has its roots in the every day knowledge that ani-
mals and plants are to some extent different from one
another. Applying this method consistently and with suffi-
cient rigor for the present inquiry, the problem formulates
itself as follows : How far do the readily observable re-
semblances and differences betw^een organisms reach down
into their chemical make-up? Does the present state of
advancement of biochemistry warrant the supposition that
for every well-established similarity and for every well-es-
tablished difference between organisms, both as to individuals
and species and as to structure and function, there is a
corresponding chemical siinilarity and difference?

84 The Unity of the Organism

{a) Different Odors and Flavors of Animals and Plants as

Distinguish ahlc hy Man

The attcni])t to answer these questions should be prefaced
by calling attention to the fact that experience is very
familiar with a group of phenomena that bears directly on
the problem even though not much definite chemical knowl-
edge of these phenomena has yet been acquired. I refer to
the odors and flavors so wide-spread in the organic world.
Everybody knows that the odor of the cow is different from
that of the sheep, and that that of the pig is different from
both. Equally familiar is the fact that the flavor of the
meat of these three animals is different. Apples are dif-
ferent from pears in both smell and taste, as are peaches
from apricots. No one with normal senses of smell and
taste would ever mistake potatoes for turnips even thoug'.i
he did not touch or see them. We might go on indefinitely
mentioning differences of this sort in both the animal and
plant worlds. That these differences have a chemical basis
is certain. As is well known, the odors of living animals are
to a large extent dependent upon tlie secretions of various
glands of the skin, some of these being sweat-glands and
others glands of more specialized character. But the urine
and feces contribute much to animal odors, a large number
of more or less well known chemical substances being im-
plicated ; and the flavors of meat are known to be connected
to some extent with the bile.

These facts of common experience and of fragmentary
chemical experience lead naturally to more specific ques-
tions in two widely different directions. In the first place
we wish to know how far the odor differences, so sharply
characteristic of animal and plant groups widely separated
from one another in classification, hold as between groups
less and less separated; and second, we inquire whether the
phepiical differences which reveaj themselves by differences

The Oryanifim and its Chemistry 85

iii smell and taste, are the only or even the chief chemical
differences between tlie organisms concerned. Taking the
first question first, we may make it more specific by asking
if there is any evidence as to whether or not species of the
same genus and varieties of the same species are kn^own
to differ from one another in smell, or their flesh in taste.

Special students of mammals and birds seem to have given
less attention to odors as specific differences in these classes
than the subject deserves. I find little beyond incidental
reference to the matter in the literature consulted, and Dr.
Joseph Grinnell, Director of the Museum of Vertebrate
Zoology at the University of California, writes "I know of
no naturalist who has attempted to make a general classi-
ficatory stud}^ of odors." Answering my question as to
whether the different species of skunks and petrels are dis-
tinguishable by their odors, this experienced naturalist tells
me he cannot smell any difference between two species of
skunk, a Spilogale and a Mephitis^ and that the species of
the genus Oceanodroma (petrels) produce an odor which,
"as far as my experience has gone, seems identical in all
the species." But Dr. Grinnell says he can distinguish a
weasel from a skunk by smell, not only in the volume as one
might say, but in the quality of the odor. And the two
genera Mustila and Mephitis to which these animals belong,
are allowed by all mammologists to be rather close of kin.

As to petrels, Mr. L. M. Loomis, whose work on the water
birds of the Pacific Coast of North America is mdely and
favorably known, writes : "The strong musky odor of the
petrels renders their discovery in the rock piles easy. It is
only necessary to insert the nose into likely crevices to find
them. With little practice one may become very expert
in this kind of hunting, readily detennining whether it is an
auklet or a petrel that has its residence in any particular
cranny." The auklets and petrels are rather widely sep-
arated in the S3^stem of classification, being assigned to dif-

86 The Unity of the Organism

ferent orders. Nevertheless their similarity in food and
other habits makes this difference in odor interesting.

The great variety not onl}^ as to form and secretion but
as to position on the body, of the scent glands in the mam-
malia has an obvious bearing on the topic in hand. The
abdominal glands of the shrew-mice, the hip glands of the
mouse genus Microtus; the leg glands and foot glands and
suborbital glands of the deer family ; the anal glands of
many orders ; and the almost universal presence of glands
whose secretions are odoriferous connected with the sexual
organs, may be mentioned as illustrating the w^de distribu-
tion of such structures in the body. And it is noteworthy
that these may be present or absent in closely allied forms.
Thus the Indian rhinoceros {Rhinoceros indicus) is said
to have hoof glands while the Sumatran species (i?/i. Su-
matrensis) has none.^^

The well known fact may also be recalled that scent
glands are often distinctive of the sexes. The musk-deer
{Moschiis moschiferus) affords a particularly striking il-
lustration of this, not merely as to the production of the
perfume which makes this animal famous, but as to a glandu-
lar secretion of quite another sort. In the adult male there
is a naked area around the root of the tail which is, as
Darwin expresses it, "bedewed with an odoriferous fluid."
This area is neither devoid of hair nor secretory in the
female at any time in life, nor does it appear in the male
until he is two years old. Tliat the musk-gland of this
species is a strictly masculine affair goes without saying
when it is recalled that it is connected with the male sexual
organs.

Ants are particularly instructive from this as from many
other standpoints, the sense of smell in them being of far
greater importance relatively to the other senses than in
the higher orders. This has been established particularly
by the admirable researches of Forel and Wasmann. Cor-

The Organism and its Chemistry 87

responding to the high development of the olfactory sense
there is a great diversity of odoriferous substances produced
by these animals. Something of the extent of this diver-
sification is indicated by Wheeler, the foremost student of
ants in this country, who remarks: "Even the degenerate
human olfactories can detect the different species and in
some cases even the different castes of ants (Eciton) by their
odors." ^^

Among plants there are many examples of easily recog-
nizable differences in smell and taste between species of the
same genus and even between varieties of the same species.
In some species of Rhus, for example R. integrifolia, the
ripe fruit is covered with a thick, white, pasty exudate
which is extremely sour, while the fruit of R. laurina has
no trace of such a product. Since these species are both
native of southern California and often occur together, they
furnish an impressive instance of difference in chemical ac-
tivity of two closely related plants. While referring to
RhuSy the familiar fact that some of the species as Rhus
lobata "Poison-oak" produce an exceedingly active poison
while others do not, may be noted as a case of undoubted
chemical difference between species that are close of kin.
And this difference in the poison producing habit of plants
is rather common and found in widely separated portions of
the plant world. The cases of Rhus and Solanum, some
species of which are poisonous and some are not, chosen
from the higher plants, are paralleled by the genus Amanita
(mushrooms) among lower plants. According to Charles
Mcllvaine, of the twenty-seven species of the genus, nine are
edible, nine are known to be either deadly or are so closely
allied to deadly species that it is unsafe to class them as
other than poisonous ; while about the others nothing is
known in this regard.

Some tests on apples make it highly probable that the
different kinds might be distinguished from one another to

88 The Unity of the Organism

a high degree of nicety, by smelling them. This is the case
with three varieties selected by chance and known locally as
"wine-saps," "pippins," and "pearmains." In attempts to
recognize them blindfolded the successes were considerably
more numerous than the failures. This conjecture is clearly
supported by the familiar fact that some groups of varie-
ties, as for example the russets, are less odoriferous than
other gr'oups ; and that other varieties as the "belle fleur"
have a higlily characteristic odor.

The suggestion that not only apples and fruits and flow-
ers are distinguishable by their odors to a far greater ex-
tent than we are accustomed to suppose, is in keeping with
the well known trade practices of tea-tasting, wine-tasting,
tobacco snifling and so on.

(h) Differences in Animal Odors as Distinguished hy Animals

Themselves

Even though the little eff*ort that has been made by na-
turaKsts to distinguish species and varieties of animals and
plants by smell does not warrant the assertion that differ-
ences of this degree of refinement do not exist, it yet would
not be worth w^hile to speculate on the possibility of their
existence had we not evidence of their existence of quite a
diff*erent sort from that furnished by the naturalist's nose.
I refer to the evidence furnished by the noses of the animals
themselves ; evidence, in a word, of the extent to which ani-
mals recognize one another by smell. Although we have
only a few thoroughgoing researches in which animals have
been made to serve through their sense of smell as analytical
chemists of one another, the few we have are exceedingly
interesting. The case of ants which has received so much at-
tention in recent years may be brought forward first in
illustration of the point. "The multiplicity of lodors," says
Fore], "is enormous, and it is possible to demonstrate, as I

The Organism and its Chemistry 89

have done for the ants, and von Buttel-Reepen for the bees,
that these animals in distinguishing their different nest-
mates and their enemies, betray nothing beyond the percep-
tion of extremely delicate and numerous gradations in the
qualities of odors." ^^ And continuing the statement quoted
from above relative to the odors of ants recognizable by
man, Wheeler says, "but these insects carry the discrimina-
tion much further. They not only differentiate the different
odors peculiar to species, sex, caste, and individual, and tlie
adventitious or 'incurred' odors of the nest and environ-
ment, but, according to Miss Fielde, tliey can detect 'pro-
gressive odors' due to change of physiological condition
with the age of the individual." ^^

Miss Fielde's formulation of her hypothesis referred to
by Wheeler is as follows: "1. The Specific Odor — The moth-
er-ant transmits to her offspring the distinctive odor which
is identical for ants of all ages and of both sexes within
the species. 2. Progressive Odor. — Female ants, including
queens and workers, have, beside their specific odor, an odor
which m^y be termed progressive. Queens of different lin-
eage have different progressive odors. In a queen this odor
is either unchanging or changes very slowly, and it is sim-
ilar to that of her newly hatched offspring. As worker-
ants advance in age their progressive odor intensifies or
changes to such a degree that they may be said to attain
a new odor every two or three months." ^'*

To Ernest Seton is due credit for the nearest approach
tliat has been made to a scientific application of this metliod
of discovering chemical differences between animals of the
vertebrate orders. The theory of what he calls scent-
language is founded on his study of carnivorous animals
which hunt by smell.

Nor can we, while on this subiect of odors as a means by
which individual animals of the same group distinguish one
another, neglect the case of the human animal.

90 The Unity of the Organism

The well known fact that some at least of the races of
mankind emit distinctive odors may be first alluded to.

"The Lord He loves the nigger well,
He knows His nigger by the smell,"

is the way the negroes of the West Indies are said to express
their claim to distinction through this character. Anthro-
pologists generally recognize that races are differentiated to
some extent in this way. Thus Deniker,'' while not certain
that the claims made by such travelers as Erman and Hue,
can be fully allowed that populations may be recognized by
their odors, still affirms the constanc}^ of difference between
some races in this regard. He accepts the statement that
peculiarities in the smell of negroes and Chinese cannot be
fully obliterated even "with most scrupulous cleanliness."
Nor has this author neglected to note the importance of
distinguishing between odors that are "sui generis" as he
says, and those due to odoriferous foods or other substances
with which certain peoples are habitually associated.

Ludwig Hopf asserts, largely on the authority of Jager,
that "some people have the power of differentiating rela-
tively insignificant odours of individuals as well as family
odours, and even the peculiar scent attaching to th^ inhabi-
tants of the same village (spezifische dorferriiche)." ^^

The Naturalist's Approach to Biochemical Problems

We now pass to the examination of the chemical nature
of organisms as this has been determined by chemical re-
searches proper. The first remark to be made under this
head must be on the exceedingly detached and haphazard
character of the knowledge in this realm when it is looked
upon from the standpoint of the zoologist and the botanist.
I hasten to explain my meaning of "detached and haphaz-
ard" and of being "looked upon from the standpoint of the

The Orgnnifim and its Chemistry 91

zoologist and botanist" for the statement may sound dep-
recatory of biochemistry and its allied branches.

As to actual quantity of knowledge and also as to the
complexity and reconditeness and exactness of much of that
knowledge, the chemistry of organisms is an impressive and
admiration-compelling science indeed. When, however, the
naturalist plunges into the great archives and monographs
and handbooks in which the knowledge is stored, that he
may find what there is that will contribute to the deepening
and broadening of his systematic information about and in-
terpretation of the animal and plant worlds, he soon becomes
aware that this knowledge has not been gathered with any
reference to the initial and most elementah needs of liis en-
terprise; that is, with reference to the necessities of describ-
ing and classifying the natural objects, the animals and
plants -wdth which he deals. What he finds is that the in-
vestigators who have produced the knowledge have been
in the main impelled by their interest in certain junctions
as displayed by the most familiar animals and plants, man's
own organ-activities being by far the most usual starting
point. For example, some young physiologist, ambitious
and energetic, becomes interested in a particular function,
say the circulation of the blood or muscular contraction or
digestion, wins a reputation by his studies, and being, as
most investigators have ever been, a teacher in some institu-
tion of learning, draws assistants and students into the re-
searches, and much new knowledge, with perhaps a whole
system of theoretical views, is developed concerning this
particular activity. And what has been the material on
which the researches have been prosecuted .^ If blood and
its physiological role stands at the center of his interest,
blood first and foremost, is what he wants and must have
for his studies. What animal within wide limits it comes
from matters little. The very fact that a fluid is found
in many animals so alike as to receive a single name, bloody

92 The Unity of the Organism

accepted without question as applicable in all the cases, is
a guarantee that it has more in common in all the cases
than the attributes by which it is familiarly recognized. For
instance the redness of the fluid in all vertebrates makes it
almost certain that with the obviously common color there
will be other coinmon attributes not obvious to ordinary ob-
serv^ation. And so it happens that our physiologist goes
to the dog or the ox or the horse or the rabbit, or with a
little more hesitancy, to the frog for his supply, these being
as a rule the most convenient sources.

One cannot reflect too carefully on tlie diff'erence between
this mode of approach to the phenomena of organisms, and
that peculiar to the natural historian. Consider a moment
the difference as touching one thing, the blood, and as be-
tween only two animals, the dog and ox let us say. Notice
first that whereas the physiologist's primary interest would
be satisfied with what he might get from a study of tlie blood
of either of these animals without reference to the other,
not so with the naturalist. Just blood is what the physiolo-
gist is concerned witli in this particular series of researches.
Comparison is no essential part of his enterprise. All he
does in this way is incidental, is secondary. Could he get all
the dog's bliood he needed to make out all that can be learned
about that blood, he would never concern himself as a strict
physiologist about the blood of any otlier animal. The
physiologist so far as he holds himself to his calHng, and
accepts his calHng as it has delimited itself in modern times,
namely, as having for its field one aspect of organisms,
i.e., their functions, can never consistently go outside of
function except incidentally — except for such morphological
facts as are essentially related in one way or another to
function. To the physiologist blood is blood no matter
whether from a dog or an ox.

To tlie zoologist, on the other liand, blood is never just
blood. It is always blood of a dog or of an ox, or of some

The Organism and its Chemistry 93

other animal, for the animal as an animal, the dog as a
dog, the ox as an ox, is an avowed concern of his. So it
comes about, as said in a former section, that the compara-
tive method is fundamental to tlic naturalist. From this it
directlv follows that for him differences between organisms
are no less basal than are similarities. As a zoologist in the
strict sense he is no more concerned with the problem of
wherein the bloods of the doo; and the ox are alike than in
that of wherein they are unlike. This is so because the dog
and the ox being both animals, neither can be to him of any
more significance or interest than the other, so that which
makes the dog a dog is no more and no less significant than
that which makes the ox an ox, and it matters not at all
whether the differentiating attributes pertain to the feet
or teeth or ears or stomach or blood. See then what this
implies as regards the zoologist's attitude toward the chem-
ical makeup of the dog and the ox. He wants to know
everything about the chemistry of the dog, and also of the
ox. It implies that the taxonomizing naturalist must be
chemical-minded to some extent and also that the biochemist
must be a taxonomic naturalist to some extent.

That the comparative method, so fundamental and indis-
pensable to the naturalist, becomes no less so to the bio-
chemist before his work is done, finds no better illustration
than in this very problem of the chemistry of the blood.
The effects of the bloods of different species of animals upon
one another has now become a recognized and important
branch of biochemistry. But here is a point the significance
of which neither biologists nor chemists appear to have fully
grasped : the discoveries in this field could not have been
made by any other means than those by which they were
made, that is, by actually mingling the bloods of different
animals in the living animals. Chemical discoveries of great
importance are here dependent absolutely on one of the
naturalisfs most cherished methods, the comparative, the

94 The Unity of the Organism

chemist having, however, sui'passed the iiaturaHst in the
refinement of the method. This coming of the chemist into
the field of the taxonomist is of the utmost interest to the
naturalist, since on the naturalist's principle of "neglect
nothing" it is impossible for him to be satisfied until he
knows the chemical as well as the anatomical and histolo-
gical makeup of organisms.

Not organic-chemistry nor physiologic- nor bio-chemistry
is what he wants, but homonine, bovine, canine, salmonine,
quercine chemistry, and so on. Surely nothing less than
this will satisfy him and probably this will not, for even it
is only generic chemistry; it is not species chemistry, much
less individual chemistry, and in all probability the time
is not far distant when he will demand individual or per-
sonal chemistry.

From the standpoint of chemical practice this demand is
almost overwhelming. Take a live dog or even a live shark
to the best manned and best equipped chemical laboratory
on earth and seriously propose that a complete chemical
analysis be made, and what sort of an answer do you sup-
pose you would get? Still more what will the answer be
when you go on to say to the director of the laboratory that
the analysis of this dog alone will not meet your needs, but
that one other animal at least must be analyzed with equal
care and completeness since your enterprise is as essentially
comparative as it is descriptive and that really what you
will finally call for will be an equally thorough analysis of
every animal.

These reflections lead straight-away to the inquiry, first
in a general way, as to how much may be found in the store-
houses of chemical knowledge that is to the naturalist's
pui'pose; and second, as to whether or not chemical re-
searches of the sort needed by him have been undertaken
to any extent. Or turning this into language in which the
naturalist is wont to express himself, how far has biocheii]-

The Organism and its Chemistry 95

istry become systematic biochemistry? How far has it. un-
dertaken to contribute to the vast task of describing and
classifying and interpreting tlie world of limng beings? Or
varying the form of the question a little, how far has biotic
chemistry become biologic chemistry? How far has the
chemistry of organisms become biologically scientific in the
systematic sense?

Some Biochemical Results Viewed from the Naturalist^s

Standpoint

With a stronger desire to indicate a naturalist's apprecia-
tion than to observe historical or logical sequences in treat-
ment, I speak first of the most important research which
up to that time had been made in this direction. Reference
is made to the monumental undertaking conceived and now
well advanced by E. T. Reichert. The title to the install-
ment so far published deserves special notice : "The Differ-
entiation and Specificity of Corresponding Proteins and
other Vital Substances in relation to Biological Classifica-
tion and Organic Evolution ; The Crystallography of Hemo-
globins."

Highly significant from the standpoint of method no less
than from that of accomplishment is the fact that in order
to carry through this piece of work, Reichert was obliged
to associate himself with a mineralogist, and that in his
university colleague, A. P. Browm, he found a man both
capable and willing to undertake the task.

(a) Reichert and Browns Results on Haemoglobin

The discussion will be best served by seeing first the main
factual results of the research. Afterward Reichert's mode
of approach and interpretation of these results can be con-
sidered. Reichert has summed up in a short paragraph of

96 The Unity of the Organism

the preface written by himself alone what was made out by
the observations : "It has been conclusively shown not only
that corresponding hemoglobins are not identical, but also
that their peculiarities are of positive generic specificity,
and even much more sensitive in their differentiations than
the 'zooprecipitin test.' Moreover it has been found that
one can with some certainty predict by these peculiarities,
without previous knowledge of the species from which the
hemoglobins were derived, whether or not interbreeding is
probable or possible, and also certain characteristics of
habit, etc., as will be seen in the context. The question of
inter-breeding has, for instance, seemed perfectly clear in
the case of Canidae and Mnridae, and no difficulty was ex-
perienced in forecasting similarities and dissimilarities of
habit in Sciurldoe, Murldae, Felidae, etc., not because hemo-
globin is per se the determining factor, but because, accord-
ing to this hypothesis it sei"\'es as an index (gross though
it be, witli our present knowledge) of those physico-chemical
properties which serve directly or indirectly to differ-
entiate genera, species, and individuals." ^^ This investiga-
tion was extended to the blood of more than one hundred
species of vertebrates and included representatives of all
the classes of the phylum, though many more mammals
than any of the other classes were studied. In several gen-
era, as Canis and Felis, a number of species and varieties
were included.

The crystallographic method was used almost exclusively
in the investigation. Concerning the value of this method
for recognizing cliemical similarities and differences, the au-
thors, trusting partly to such authorities as Groth, rest on
the view that "Differences of chemical constitution are ac-
companied by differences of pliysical structure, and tlie
crystallographic test of the differences of chemical consti-
tution is recognized as the most delicate test of such dif-
ferences." ^^ In accordance with this the dictum, "Sub-

The Organism and its Chemistry 97

stances that show differences in crystallographic structure
are different chemical substances" ^^ is accepted.

As far as the conditions of the researches would permit,
the crystals of oxyhemoglobin were made the standard of
comparison. When several forms of this are obtained from
the same blood "eacli form, A-oxyhemoglobin, B-oxyhemo-
globin, etc., appears always in its own proper form and
axial ratio when the blood of different individuals of the
same species are examined. The same is true of the
other hemoglobins — metoxyhemoglobin, reduced hemoglobin,
methemoglobin ; so that the hemoglobins of any species are
definite substances for that species. But upon comparing
the corresponding substances in different species of a genus
it is generally found that they differ the one from the other
to a greater or less degree ; the differences being such that
when complete crystallographic data are available, the dif-
ferent species can be distinguished by these differences in
their hemoglobins. As these hemoglobins crystallize in iso-
morphous series, the differences between the angles of the
crystals of the species of a genus are not, as a rule, great;
but they are as great as is usually found to be the case
with minerals or chemical salts that belong to an isomor-
phous group." ^^ In illustration we may select the table
for the species of cats studied, this being based on the crys-
tals of reduced hemoglohi/n. Tlie crystals belong to the
orthorhombic system and are optically positive for all the
species, so these items need not appear in the table.

Angle of unit

Angle of

ISame of Species

Axial ratio

prisms (normals)

macro donne
normals

Felis leo

0.9743:1:0.3707

88 30'

41 50'

F. tiajris

0.9742:1:0.3838

88 30'

43 0'

F. bengalensis

0.9657:1:0.3667

88 0'

41 35'

F. pardalis

0.9489:1:0.3931

87 0'

45 0'

X

F. domestica

0.9(5.56:1:0.3839

88 0' ■

43 20'

I^ynx rufus

0.9869:1:0.3914

89 15'

42 46'

L. canadensis

0.9605:1:0.3944

87 42'

41 30'

98 The Unity of the Organism

As another example the table for the crystals of B-oxy-

heiiioglobin from the baboons of the genus Papio is chosen.

These all belong to the monoclinic system and all except

those from the Guinea Baboon (P. sphinx) are optically

positive.

Prism,
Name of species Axial ratio Angle B angle

Yellow Baboon {Papio babuin) 1.6808:1 :c' 72° 72' 30" 118 30'

Guinea Baboon (P. sphinx) 1.8418 :l:c' 70° 123 0'

Long-armed Baboon (P. Langheldi) 1.655 :l:c' 70° 30' 117 44'

Chacma (P. porcarius) 1.732 :l:c' 75° 120 0'

Anubis (P. anubis) 1.737 :l:c' 72° 30' 120° 11'

So far as one with little knowledge of crystallography
may judge the numerous tables of which these two are sam-
ples, the copious illustrations many of which are from pho-
tographs, and the discussions, seem to justify fully the
generalizations above quoted, with others to which no ref-
erence has been made. It would however be quite wrong to
gain the impression that the very positive conclusions as to
the specificity of hemoglobin crystals reached by these
authors is in accord with all researches that have been made
on the subject. Summing up their rather extensive re-
view of studies previous to theirs, the authors say : "Equally
expert observers working with blood of the same species
have arrived at very different conclusions as to the specific-
ity or non-specificity of hemoglobin crystals in relation to
species, some claiming that the crystals are occasionally
specific, others that they are always specific, and others that
they are not specific because the same blood may yield crys-
tals of very different forms and that the differences are
probably accidental. Crystals of various colors and vary-
ing forms have been obtained from the same blood." ^^

A highly significant thing that comes from considering
the results reached by those students who have opposed the
idea of specificity of hemoglobin from different kinds of
animals, is not that they claim that all hemoglobin crystals

The Organism and its Chemistry 99

are alike, or even that only a few sorts can be demonstrated,
but that the great number of kinds do not correspond in
any definite way to different kinds of animals. And here
comes the particular point made against these views by
Heichert and Brown — and it is of great importance gener-
ally, and peculiarly interesting to the natural historian.
They show that the reason wlu' so many previous observers
have failed to find a correspondence between kinds of crys-
tals and kinds of animals, is that the crystals have not been
described zmth sufficie7it fulness and accuracy. In a word
the issue is, to the naturalist, the old and familiar one of
descrijjtion, comparison and classification. For example,
the authors lay particular stress upon the insufficient atten-
tion hitherto given to the crystal fomis of the different
sub-species of hemoglobins, namely, oxyhemoglobin, re-
duced hemoglobin, metoxyhemoglobin, methemoglobin, etc.
Again they point out the great inadequacy of earlier studies
in the determinations of the axial relations and other phys-
ical attributes of the crystals. The upshot of their cnti-
cism of previous studies as seen in the light of their own,
is that when a classification of hemoglobin crystals from
the blood of many kinds of animals is based on sufficiently
thorough going description, that classification correlates
itself with the kinds of animals from which the blood is
taken.

(6) The Precipitin Reaction Between Bloods of Different

Animals

If our comparative chemical knowledge of vertebrate
blood were limited to the results of studies like this by
Reichert and Brown, the presumption in the absence of very
positive evidence to the contrary, would yet be strongly
in favor of the hypothesis that the blood of each animal
species is in some of its constituents unique to that species.

100 The Unity of the Organism

As is now widely known, this hypothesis is supported by
another great mass of evidence from quite a different source,
whicli though not as directly cliemical as that just adduced,
is still so clearly so in its implications that reference to it
in this chapter is undoubtedly justifiable. What is in mind
arc the discoveries of recent years touching the compatibility
and non-compatibility of the blood of one kind of animal
for that of another kind ; discoveries in other words, con-
cerning the so-called "precipitin reaction" as between or-
ganisms of different kinds. Although this subject has at-
tracted a good measure of attention, only a portion of its
more fundamental significations has been much regarded.
Its bearings on problems of affinity and racial descent, for
example, have elicited their due of interest. But its con-
tribution to light upon the o]:)posite aspect of animal nature,
namely, that of difference as well as of likeness between
kinds, has not been appreciated in proportion to its merits.
Once grasp the conception of each organic species, to say
nothing of each indi\adual, as something genuinely unique
in the world in certain of its more obvious attributes, as a
scheme of organization, shape, etc., and then extend this
down into basal composition and process, so that the organ-
ism is seen in its role not merely of transformer and creator,
but to some extent of exclusive transformer and creator of
the elements of which it is constructed, and these and kin-
dred discoveries fall into their right perspective of meaning
and interest.

The underlying general principle of the precipitin reac-
tion i^ that of the production within the organism of anti-
hodies as a result of injecting into it certain foreign sub-
stances which, when the reaction occurs, are known as anti-
ge7is, the anti-gerhs and anti-bodies usually reacting definitely
and specifically upon each other. In one form of this re-
action the antibody acting upon certain proteins, forms a
precipitate, this precipitate carrying down both the antigen

The Organhm and its Chemhirif 101

and the antibody. The point of special significance for us
now is tliat the blood of a given species of animal has been
found to act as an antigen when injected into the circula-
tion of another species, and the extent of the reaction is in
large measure dependent on the degree of affinity between
the animal species to which the different bloods pertain.

A particularly instructive case worked out by Hamburger
is given by Arrhenius. Serum from a rabbit was treated
with serum from a sheep, the rabbit serum being in this way
made to contain an antibody. The rabbit serum tlms af-
fected was then used for experimenting upon the serum of
a normal sheep, a goat and an ox, with a view to testing
(juantitatively the action in the three cases. The same
quantity of rabbit serum containing the antibody was used
in each case, as was also the same quantity of equally diluted
serum of the animals to be tested, and the amount of pre-
cipitate in each case was measured. The results given in
terms of the antibody or precipitin, rather than in that of
the precipitate are, in Arrhenius' words, as follows: "On
injection of sheep-serum into rabbit blood we have obtained
an antiserum containing per centimeter cube 300 equivalents
of ])recipitin against sheep-serum, 212 equivalents of preci-
pitin against goat-serum, and only 90 equivalents of pre-
cipitin against bullock-serum." ^^ This result is obviously
in agreement with the general zoological evidence that the
goat and the sheep are somewhat closer of kin than the
ox and the sheep or the ox and the goat.

Another inference of quite different import drawn from
the experiments is not to be missed, namely, that the dif-
ferent amounts of precipitation in the three sera is not due
merely to a quantitative difference in the precipitin con-
tained in the rabbit serum, but that there are really three
precipitins involved. This conclusion, Arrhenius points out,
se^ms necessitated by the fact that a unit quantity (1 c. c.)
of the normal serum from each of the three animals tested

102 The Unity of the Organism

contains nearly the same number of equivalents of the
precipitate.

In his well known work Blood Immunity and Blood Re-
lationship, G. Nuttall has applied this principle more widely
to the animal kingdom than any one else.

(c) Comparative Chemistry of the Sperm of Different

Species of Fislies

Several biologists are impressed with the importance of
knowledge in tiiis field as bearing on philosophical natural
history. No physiologist has so far as I am aware, ventured
quite so far into the realm of prophecy with reference to it
as has E. Abderhalden. He points out the possibility of
increasing the number of attributes now recognized as dis-
tinguishing not only species but individuals through a sys-
tematic and concerted carrying out of researches already
begun in this field, and foresees the time when biochemistry
will play a leading role in problems of racial descent and
taxonomic affinity.-^ The march of research in the decade
since Abderhalden made these forecasts, has undoubtedly
been toward a fulfillment of them, at least as touching bio-
chemical distinctions between individuals. Thus C. Todd
has very recently given a useful summary of what has been
done up to the present hour on the comparative chemistry
of the blood as revealed by the methods here being consid-
ered, and an account of an exceedingly interesting resarch
of his own.

The chemico-zoological researches standing next in in-
terest and importance to those on the blood are the well
known ones inaugurated by ^liescher and continued by Kos-
sel and liis students, on the spermatozoa of fish. Miescher
discovered in the sperm of the salmon a group of protein
substances called by him protamines, which are said not
to have been found as yet elsewhere than in fish sperm.

The Orgavism and itfi Chemistr?/ 103

There has been some question whether these are true
proteids, but at any rate they seem to be relatively simple
and definite in composition so that Kossel has regarded
them as the foundation of the protein bodies. It has been
possible to^work out probable empirical formulae for them,
and herein their natural history significance comes strikingly
to view. The formula C32H54N18O4 was assigned by Miescher
to the protamine of Salmon sperm, the substance being
proved to contain the nucleic acid radical. The comparative
studies of Kossel and his students extended to the sperm
of the herring, mackerel, sturgeon, and perch, and brought
out the fact that while the nucleic acid part of the molecule
is the same for the different genera, the basic part is dif-
ferent in each, so a name is required for the protamine de-
rived from each kind of fish. The names salmme, clupeme,
scombrine, sturine, cyprinine, cyclopterine, etc., proposed
by Kossel have consequently come into general use. These
differ in formulae. Thus Kossel gives clupine as C30H62N14
O9 and sturine as CseHegNigOy. They also differ in the
cleavage products yielded, histidine for example, being ex-
tracted from sturine and from none of the others, and tyr-
rosine from cyclopterine exclusively. All, on the other
hand, yield arginine while lycine was found only in sturine
and cyprinine, and so on.

(r/) Comparative Chemistry of Milk From Different Species

The milk of several species of mammals has been ex-
tensively investigated mostly from physiological and dietetic
standpoints, but the difference between the milks of dif-
ferent groups has come out with positiveness. It seems that
on the whole the milks of carnivorous species are more alike,
and those of herbivorous species are more alike, than those
of either of these categories are like those of the other, but
there are not enough observations to warrant laying this

104 The Unity of the Organism

down as a law. As thorough a chemico-zoological investi-
gation of milk as that made by Reichert and Brown of
blood, ought to yield highly interesting results, for not only
common knowledge, but technical knowledge as well, obtained
in connection with the dairy industry recognizes that even
as between different breeds of cows the milk differs in con-
stitution. Jersey cows for example, produce milk contain-
ing a larger proportion of butter fat than do Ayrshires, and
some at least of these breed-differences in milk cannot be
explained on the basis of differences in food or other en-
vironmental factors, powerfully as these do undoubtedly
influence milk.

Attention may be called to the extreme chemical sensitive-
ness of this fluid as a registering instrument. "Circum-
stances tending to cause discomfort usually lower the pro-
portion of volatile acids present in the butter-fat, but the
variation in the composition is very irregular, and appears
to depend partly upon the nervous temperament of the
cow." ^^ And there is ample evidence that the character of
the milk of women may be so changed by nervous and mental
conditions as to become unfit for the nursing babe.^^

{e) Comparative Chemistry of Digestive Enzymes

Another great field of chemico-zoological research has
recently been opened up by studies on the enzymes of diges-
tion. The investigations of this sort which we will notice
have been specially prosecuted by the Swedish chemist, S.
Hedin. The results are given in outline by A. Hardens
and from this the following statement is, in the main,
drawn. ^^ The problem concerns rennet, the familiar milk
clotting substance produced in the calf's stomacli, and
Hedin's results are not influenced so far as I can see, by
the much debated question of whether or not pepsin and
rennin are two entirely distinct bodies. It is shown that the

The Organism and its Chemistry 105

mother-substance, the zymogen, of the clot-inducing sub-
stance is not simple but is a compound of the enzyme and an
inhibitant for that enzyme. By proper treatment of the
water extract of rennet with dilute acid, the enzyme is
liberated and the inhibitant destroyed, while if the treat-
ment be with dilute alkali the enzyme is destroyed and the
inhibitant liberated. But if the solutions containing the
two opposing substances are mixed, recombination takes
place and the resulting solution has the attribute of the
original water solution of rennet, namely, that of clot-pro-
duction to a sliglit degree only.

To be specially noted is tlie fact that the inhibitant of a
given rennet neutralized the enzyme of that same rennet.
Now comes the thing of special importance from the stand-
point of comparative zoology : When solutions of both en-
zymes and inhibitants are prepared from different species
of animals (the calf, the jjig, the guinea pig, and the pika,
were used in the experiments), it turns out that tlie in-
hibitant from the rennet of one species does not inhibit the
enzyme from the rennet of another species. And so it is
concluded that ''both the enzyme and the inhibitant are dif-
ferent for each animal, a fact of great interest and impor-
tance," to repeat Harden's words.

Special attention should be called to the circumstance that
not only is this another method of differentiating species
chemically, but that it is an exceedingly delicate me'thod.
This is particularly seen in the fact that the rennets of the
species investigated were found capable of clotting cow's
milk in spite of their being different in other respects as
just shown, it being thus revealed that the fact that rennets
from two different animals may act alike on cow's milk,
does not prove them to be alike in all their attributes. No
careful student of nature will ever neglect the principle
involved in this. We may take this as an impressive re-
minder that the problems of the dependence and the inde-

106 The Unity of the Organism

pendence of characters, so much to the front now in con-
nection with the Mendelian mode of biological inheritance,
extends down into the chemical reactions taking place within
the organism.

(f) Instances in General Biochemistry Where Interesting
Facts of Comparative Chemistry are Incidentally

Brought Out

If now, taking our cue from these several distinct groups
of positive evidence of a close correlation between attributes
by which the naturalist ordinarily distinguishes individuals,
varieties, species, genera, etc., and chemical attributes of
these groups, we look through biochemical works which have
no natural history intent so far as their authors are con-
cerned, with the end in view of seeing to what extent they
nevertheless contain incidental facts and statements which
are in keeping with the results of the chemico-zoological re-
searches just considered, we find an almost unlimited number
of records of such import. We will notice a few of these,
selecting them mainly with reference to the very wide range,
both chemical and biological, from which they may be drawn.

One of these works has lately produced good experimental
reasons for believing that trypsin of the liver of "the star
fish" is considerably different from that derived from the
same organ of the "large soft-shelled California Clam." So
far as concerns the research here referred to, what species
of starfish was used probably did not matter much, but to
the zoologist bent on pushing as far as possible his knowl-
edge of the differences between animals, the point is of
genuine interest since the fragment of information thrown
out might serve as the starting place for an important
cliemico-zoological study of the organs rather indiscrimin-
ately called liver occurring in many invertebrates. But
even this additional knowledge, for we have much besides,
favorable to tlie conception that trypsin can never be looked

The Orgnmsm and its Chemisfr?/ 107

upon as just trypsin, but must be regarded as the trypsin
of some particular species, or possibly variety, or even
individual.

A. P. Mathews, more regardful of the source of his scien-
tific blessings, that is, of the material on which he works,
as well as of other essentials, is explicit and informs us that
the eggs of the sea-urchin Arbacea punctulata, differ
markedly in their physiological properties from those of
the stai*fish Asterias forbesii. The differences in "physi-
ological properties" noticed consist in the greater stability
of the sea-urchin egg as manifest in its resistance to oxida-
tion, low rate of respiration, and relative insensibility to
stimuli inducing artificial parthenogenesis. These differences
Mathews finds to be correlated with the possession by the
sea-urchin egg of considerable quantities of the widespread
substance cholesterol, and the absence either wholly or in
part, of that substance in the starfish egg.

The Coalescence of Natural History and Comj)cirative

Chemistry*

It seems then from all this that natural history and bio-
chemistry are being inevitably drawn together by the very

* Since this chapter was written J. Loeb's The Orc/anism as a Whole
has been published. It is gratifying to find in this book evidence that
the author is being carried, as it seems to me, unconsciouslj'^ perhaps,
toward the organismal and natural history standpoint. One piece of
such evidence may Ije appropriately noticed at this point. It is that
I.oeb gives us a chapter with the title The Chemical Basis of Geims and
Species. This seems to show that now, since specificity is coming down
to a chemical basis, taxonomy is assuming a reality and significance in
this author's mind which it did not have formerly. But attention should
be called to the fact that knowledge of the chemical differentiation of
taxonomic categories has not made their reality one whit more posi-
tive than it was before. The chemist is following the naturalist and
refininy the latter's methods in certain particulars beyond anything he
himself is capable of. "In certain particulars," I say, because in certain
other particulars the naturalist is still far in advance of the chemist.
Thus the naturalist knows beyond a trace of uncertainty innumerable
"specific differences" among plants and animals which the chemist, as
a chemist, can not yet so much as touch. In fact, the lack of compre-

108 The Unity of the Organism

nature of the subject matter with which they are occupied.
Descriptive zoology and botany are to become chemical in
part, and the chemistry of organisms is to become zoological
and botanical in part. Each science is to supplement,
and reciprocally to be supplemented by the other far more
essentially than has hitherto been the case. In one of its
aspects biochemistry will become a branch of systematic
zoology and botany, just as biology in one of its depart-
ments, is already a branch of chemistry. Although such a
state of things is very far from full realization, that the
movement is in tliis direction seems unmistakable. Tlie con-
ception that animals and plants as producers of chemical
substances, and that each kind if not each individual is to
some extent a producer of different substances is receiving
new confirmation all the time.

When we pass from the primary task of identifying and
describing the chemical substances produced by different
animals and plants to that of gaining an insight into the
methods by wliicli these substances are produced; when, in
otlier words, we pass from the problems of What to those
of How, the vast complexity and uniqueness not only of the
chemical operations of organisms as distinguished from
non-organisms, but as well the uniqueness, within limits, of
these operations come even more impressively into view. A

hensiveness and of refinement in some directions of the chemist's descrip-
tions receives striking iUustration in this very book "The Organism
as a Whole." Restricting his consideration of the chemical bases of
species to the evidence drawn from laboratory experimentation, Loeb
writes: "Ford claims to have obtained proof that a glucoside contained
in the poisonous mushroom Amanita i)h(tJJokles can act as an antigen.
But aside from this one fact we know that proteins and only proteins
can act as antigens and are therefore the bearers of the specificity of
living organisms." (p. (i.'i). Exactly what is meant by "bearers of the
specificity of organisms" no one knows, but if the assertion implies, as
it seems to, that all such dift'erences are due exclusively to proteins, it
is contrary to a vast array of indubitable facts of natural history. Dif-
ferential otlors and flavors, for example, as dwelt upon above, are
certainly not all, probably not usually, proteid in nature.

The Organism and its Chemistry 109

comprehensive discussion of the problems of how organisms,
all of them., from the simplest unicellulars to the most com-
plex multicellulars, accomplish the chemical transformations
which they do accom])lish, would require a broader knowl-
edge of chemistry, both physico- and bio-chemistry than I
suppose any jU'ofessional chemist would pretend to have.
It would be, then, wholly presumptuous for one who like
myself is exceedingly meagerly possessed of first-hand chem-
ical knowledge even to touch it. Nor do I intend to do this
beyond the very simple extent of trying to present in schem-
atized fashion the various ways in which organisms operate
chemically, with the special end in view of presenting strik-
ingly to both naturalists and chemists what is in store
for them from the standpoint of research undertakings if
the ideas set forth in this chapter are to be realized.

Provisional Enumeration of Chemicot-naturaUst Inquiries

A rough-and-ready enumeration and classification of the
chemico-transformatory methods employed by organisms
may be given as follows :

1. The methods by which green plants use the radiant
energy of the sun in constructing their own substance, and
doing it in such fashion as to store away the great quanti-
ties of this energy that is characteristic of them.

2. The methods by wliicli plants utilize water and the in-
organic elements of the soil to their needs.

S. The methods by which plants store up organic sub-
stances for future needs in seeds, bulbs, roots, etc., and make
use of these supplies when the proper time comes.

4. The methods by which the organic foods of animals are
reduced to a state in which they can be taken into the cir-
culation.

5. The methods by which from the foods thus reduced the
substances of and in the tissues characteristic of particular

110 The Unity of the Organism,

species are built up; the methods, that is, of 'particular
as contrasted with general assimilation.

6. The methods, oxidative and otherwise, by which the
force liberated in muscular and other work is accomplished;
that is, the methods of particular as contrasted with general
work by organisms.

7. The methods by which the germinal elements of plants
and animals, sex-cells, plant and animal buds, gemmae, bulbs,
propagative cambium cells, etc., become so constituted as to
be able to develop into other individuals like those from which
they themselves originated.

8. The methods by Avhich the chemical substances dis-
tinctive of organic varieties, species, etc., are originally
produced, the phylogeny, in a word, of biochemical sub-
stances.

9. The methods by which acts of volition, memory, intel-
lection, and emotion are accomplished.

Peculiar Importance to Natural History of the Application
of Physical Chemistry to the Chemistry of Living

Beings

The ascertainment of details of structure and process
implied by this inventory obviously belongs to biochemistry
alone. By himself, the naturalist is helpless in his longings
for knowledge in these realms. But chemistry's initial
answer to the naturalist's appeal is not very comforting,
for if the particular chemist to whom the naturalist appeals
is broadly experienced and learned, is thoroughly objective-
minded, and quite frank, he assures the naturalist that his
request is for light in one of the darkest places in the whole
realm of chemical phenomena. Nevertheless, if plied closely,
chemistry is found to have a certain amount of positive
knowledge and certain well-supported conceptions which in-
terest the naturalist of the organismal cast of mind very

The Organism and its Chemistry 111

much — more, indeed, than they Interest the chemist himself.
This special interest of the naturalist in chemical facts and
ideas is due to his seeing possibilities in them that the chemist
sees but dimly if at all.

{a) Individuation and Speciiition of '^Organic Matter""
Fundamental Biologic Facts

That some physiologists are not fully awake to the sig-
nificance of certain of their possessions is shown, I think, by
the following appraisement of plant productions that are
used for drugs : "It is remarkable how great a variety of
these active substances are formed by plants. It seems
evident that they must be more or less accidental products
of chemical change. A very small number would suffice
for protection of the plant from being consumed by animals
for food. Similar conclusions may be drawn from the oc-
currence of adrenaline and a substance related to digitalir.
in the *paratoid' glands of a tropical toad, described by
Abel. It is impossible to see wiiat use to a toad a rise of
blood pressure in the animal which attacks it w ould be." -^

The naturalist must object to this view very strenuously.
In the first place, he is bound to point out the unquestioned
fact that these substances are subject to the law of hered-
ity, one of the securest and most probably universal of all
the laws thus far established by biology. Hence to pro-
nounce the substances accidental is to commit what may
justly be characterized as a scientific misdemeanor. Such a
pronouncement is about as unsound in the general living
realm as would be a declaration that the musical talent is an
"accidental" product in the human realm. The really mod-
em naturalist has outgrown the old practice of putting aside
whatever he can not explain as accidental or abnormal.

But the naturalist must go on and point out that if the
particular plant substances which have won the attention

112 The Unity of the Organism

of chemists because of their toxic or medicinal properties
may be regarded as accidental, then it would follow that an
incalculably vast array of the phenomena of the living world
taken as a whole would come under the same stigmatization.
This would follow from the fact that the thoughtful natur-
alist is certain that the criterion of accidental (to wit, that
of non-usefulness from the survival-of-the-fittest standpoint,
invoked by Bayliss) is no more applicable to these particu-
lar substances than to myriads of structures and substances
and activities of the most diverse sort presented by plants
and animals. To illustrate, probably a majority of all
organic odors, and all flavors so far as these are differen-
tiable from odors, would have to be cast into the scientific
discard of accidentals. In fact, I believe any open-minded
taxonomist to-day will recognize that such a criterion of
accidental would thus dispose of a majority, probably, of
the attributes upon which he depends for distinguishing
species, varieties, and races. And this brings up the ex-
ceedingly important question, is not such a physiological
conception as that expressed by Bayliss due largely to the
influence of the natural selection hypothesis, a conception
which came straight from natural history.? Bayliss's own
words seem to constitute an affirmative answer to this query.
But natural history is becoming convinced that while the
numerous activities of organisms which Darwin grouped to-
gether and named the struggle for existence are of very
great importance, they have very little originative power
in a strict sense. This conviction is being forced upon nat-
ural history from two of its main fields of research, namely
from that of taxonomy and that of genetics. The exact
taxonomic studies of to-day, especially such of them as
give due attention to the relation of the groups to their
environment, are at one with studies on mutation and Men-
delian heredity in denying to adaptation and natural selec-
tion the supreme role in evolution assumed by the Darwinian,

The Organism and its Chemistry 113

and especially the neo-Darwiniaii hypothesis.

Natural history, then, is able with a strength peculiarly
its own to deny physiology's right to set aside as accidental
myriads of biological phenomena in the interest of inorganic
hypothesizing about organic beings. Naturalists are in
position to insist that physical and chemical conceptions
as applied to organisms must be somehow so shaped that
they will neither disregard nor minimize the importance of
vast numbers of facts about the living world which natural
history from her own peculiar labors knows to be facts.

So the naturalist pushes his quest among his biochemical
confreres still more closely and broadly, for his general
scientific sense and faith lead him to surmise that some-
where chemistry has something better than the accident
hypothesis for dealing with the undeniable difficulties which
the individual, varietal, specific and generic substances and
activities present. Physiology almost certainly found the
right starting point or base of operations for a broader,
more adequate application of physics and chemistry to
biology when it recognized (as indicated on a previous
page) the fundamental difference between living and dead
protoplasm. Once the full significance of this difference
is recognized, biochemistry will be able to go ahead in its
sei*A^ice of biology — and of human weal in general — unham-
pered by hypotheses that are really narrowing because too
grasping.

Let me assure those biological readers whose scientific
thinking has been more or less deranged by the dread bogy.
Vitalism, that there is not the slightest real danger of run-
ning into Vitalism in the direction indicated. There is no
such danger because what we are here concerned with does
not raise the metaphysical problem of a Vital Force, or for
that matter of any other "ultimate force." The strictly
scientific problem before us is in deepest essence of the same
nature as it is in its most obvious, most practical expression.

114 21ie Unity of the Organism

It is this : Are a man and a dead man, a horse and a dead
horse, the same thing- or are they different things? If the
materiaHstic biologist and the fatalistic biologist will answer
this question with an unfaltering "They are different
things," and will give due attention to both the objective
and the subjective grounds on which the answer is based,
they will find that the words materialism and vitalisni, to
which they have clung so tenaciously, are emptied of any
important significance as applied to their doctrines. Both
vitalist and materialist will then become aware that the very
nature of biochemistry, its nature in virtue of which it has
a certain measure of independence, or self-sufficiency, is a
peculiar revealer of both the necessity and the method of
application of physical chemistry to biology.

So I bring this discussion of the organism and its chem-
ical substances to a close with a brief natural-history state-
ment of the probable role of physical chemistry in inter-
preting organic beings. First of all, we must insist that the
obvious, the never-refuted, the universal fact that all living
substance or protoplasm is individualized, shall not be ig-
nored or cavalierly tossed aside. Nor can we permit its
significance to be obscured by sophistical reasoning — by
such reasoning as, for example, may be indulged in from
the discovery that certain organs and cells may live for a
long time and carry on their activities more or less normally,
after being separated from the organism. What these
important observations prove is that many living organs,
tissues, and cells have wonderful tenacity of life, once theij
have been brought into existence. From this viewpoint
the facts are of great interest, but they do not furnish a
scintilla of evidence that organic substance or cells or or-
gans are independent of individual organisms in the sense
of being able to come into existence independently of in-
dividual organisms. Some physiologists talk about "organic
matter" as though it had as little connection with organ-

The Organism and its Chemistry 115

isms as has inorganic matter. "Living substance," unin-
(Hvlduated in a strict sense, has no better standing in the
world of objective reality than have the ghosts and other
a])i)aritions with which the imagination of primitive men
populates the world.

xVU the living substance that has existed on this earth
or anywhere else has existed through and in and because of
individual living beings. That this is a truism is no reason
for treating it as though it were not true.

(Z>) Indications That Variation and Inditiduatiou are
Primarily Chemical, While Constancy and Uni-
formity are Primarily Physical

Fixing attention, now, on organic matter as the matter
of individual organisms, which individuals are subject to
the laws of variation and heredity, and remembering that
according to these laws no two individuals are exactly alike,
and that every individual is derived from other individuals
which it resembles because of being thu;* derived, see how
in their very natiire physics and chemistry are adapted to
the needs of the natural historian in his efforts to interpret
the "matter" of the 'organisms with which he is occupied.
From being par excellence the science of transformation,
of the production of what is. absolutely different and abso-
lutely new relative to that from which the products come,
chemistry seems to the naturalist to be above all others
the science which ought to illuminate the variational, the
transformational, the productional side of "organic sub-
stance." On the other hand, from being par excellence the
science of the general, the persistent, the non- and quasi-
transformational side of natural objects, physics appeals
to the naturalist as the science which ought to bring light
into the darkness that envelops the repetitional, the like-
begets-like, the heredity side of the same substance,

116 The Unit I) of the Organisin

And since physics and chemistry have fused together as
regards many plienomena in their own special fields to pro-
duce a single two-parted science, physical chemistry, natu-
ral history looks with much hopefulness to this new science
for light on the "living matter" aspect of its problem. It
is almost certain that the application of physical chemistry
to the study of organisms has actually made a good start
in the very quarter which, as indicated above, the naturalist
would expect help from the new science.

As regards the Cell, biochemistry, prosecuted under the
guidance of physical chemistry, is bringing out facts and
formulating conceptions that are unmistakably organismal,
it seems to me, in their trend. Deferring to the biochem-
ist's predilection for the cell rather than for the organism,
let us reflect on how the problem of the cell presents itself
to the naturalist in one of its main aspects, that, namely,
of its eadstence only, that is, its phenomena other than those
connected with cell reproduction through division or other-
wise. The basal problem thus arising is : what Is the cell's
constitution in virtue of which it is able so to transform the
matter and the energy flowing through it as to enable it to
carry out the various activities, contraction, secretion,
conduction of stimuli and so on, peculiar to it, and at the
same time maintain its identity as a space-occupying object ;
that is, maintain its individuality.^

Place, now, alongside this formulation of the natural his-
tory problem of the cell's existence the following summary
statement of what the cell is to a biochemist who sees physico-
chemically : "But it is clear that the living cell as w^e now
know it is not a mass of matter composed of a congregation
of like molecules, but a highly diff*erentiated system ; the
cell, in the modern phraseology of physical chemistry, is
a system of co-existing phases of diff^erent constitutions.
Corresponding to the diff^erence in their constitution, dif-
ferent chemical events may go on contemporaneously in the

The Organism and its Chemistri/ 117

different phases, though every change in any phase affects
the chemical and physico-chemical equilibrium of the whole
system. Among these phases are to be reckoned not only
the differentiated parts of the bioplasm strictly defined (if
we can define it strictly) the macro- and micro-nuclei, nei-ve
fibers, muscle fibers, etc., but the material which supports
the cell structure, and what have been termed the meta-
plasmic constituents of the cell. These last comprise not
only the fat droplets, glycogen, starch grains, aleurone
grains, and the like, but other deposits not to be demon-
strated histologically. Tliey must be held, too — a point
wliich has not been sufficiently insisted upon — to comprise
the diverse substances of smaller molecular weight and
greater solubility, which are present in the more fluid phases
of the system, namely, the cell juices. It is important to re-
member that changes in any one of these constituent phases,
including the metaplastic phases, must affect the equilib-
rium of the whole cell system, and because of this necessary
equilibrium-relation it is difficult to say that any
one of the constituent phases, such as we find permanently
present in a living cell, even a metaplastic phase, is less
essential than any other to the 'life' of the cell, at least
when we view it from the point of view of metabolism." ^^

Or, again notice this : "For the dynamic chemical events
which happen within the cell, these colloid complexes yield
a special milieu, providing, as it were, special apparatus, and
an organized laboratory."

Some of the particularly important features of the "col-
loid complexes" which make them a "special milieu," i.e.,
a special environment, of so remarkable a character are:
The commingling in them of the solid and fluid, or "gel"
and "sol" conditions of the colloids ; the "surface effects" of
colloidal particles as the free surface energy, the osmotic
pressure, and perhaps the enzymic action, of such surfaces ;
the so-called adsorptive properties of solid colloids, that is,

118 The Unity of the Organism

the power the substances have, dependent upon temperature,
pressure, etc., to take up varying quantities of different sub-
stances, making them thus highly selective; and the ready
transformation of the substances back and forth from the
colloid to the crystalloid conditions to meet the needs of
the living cell.*

Such expressions as those quoted from Hopkins (and
others of similar purport could be quoted from other au-
tliors) it seems to me say merely this: The physical (in con-
tradistinction to the chemical) constitution of the living cell
is such as to enable it, as a complex unitary whole, to
accomplish the chemical transformations of substance and
energy which it is observed to accomplish, ^y its purely
physical properties, its spacial and energy magnitudes and
changes, the cell is primarily quantitative, while by its chem-
ical properties, its transfoniiation of substances and ener-
gies, it is primarily qualitative.

The physical principles implicated in organic phenomena
make of the cell an "organized laboratory," in Hopkins'
plirase, for bringing about ^Ulyncimic chemical eveuts,"'
events, that is, which are qualitatively transformative.

So our appeal as naturalists to physical chemistry for
help in interpreting tlie substances of which organisms are
composed is carrying us toward some such conception as to
tlieir individuation, apart from which we are obliged to con-
clude organic substance never exists, as that individuation
is dependent primarily on the chemical nature of the sub-
stance; while the continued existence of individuals and
their genetic repetition is dependent primarily on the phys-
ical nature of the substance.

This, I say, is the direction in which the evidence thus
far considered seems unmistakably to carry us. But we

* See especially The General Physical Chemistry of the Cells and
Tissues, by W. Pauli, in Physical Chemistry in the Sei'vice of Medicine,
translated by M. H. Fischer.

The Organism and its Chemistry

119

have not yet examined all tlie relevant evidence. For ex-
ample, what we have seen up to now does not go beyond the
cell in individuating the living substance. So a further stage
of our discussion will have to deal with the nature of the
cell and its place in the organic scheme.

REFERENCE INDEX

I.

2.
3.
4.

6.

7.

8.

9.
10.
11.
12.
13.
14.

Marshall 269 15.

Marshall 293 16.

Tangle 423; 327 17.

(a) Thierfelder ii. Stern 18.
370-385 19.

(b) Tangl u. Farkas. .624-638 20.

(c) Marshall 267-273 21.

Brooks 325 22.

Bavliss 19 23.

Hopkins 216 24.

Hopkins 217 25.

Deniker 109 26.

Hopf 240 27.

Beddard 254 28.

Wheeler 510 29.

Forel 46 30.

Fielde 1

Reichert iv

Reichert 144

Reichert 145

Reichert 326

Reichert 282

Reichert 139

Reichert 138

Arrhenius 295

Hertwig, O. ('12) 477

Marshall 6QQ

Marshall 366

Hardens 363

Taylor 343

Mathews 465

Bayliss 727

Hopkins 220

Chapter V
THE ORGANISM AND ITS PROTOPLASM

Protoplasm and Mystif^cation

NOT many words belonging to purely technical and de-
scriptive botany and zoology have become so much
involved as has "protoplasm" in obscure speculation on the
part of biologists themselves, and in more or less spurious
regard by both biologists and generally intelligent persons.
"The new Anthony studies the protean forms of life and at
the end is ravished by the sight of protoplasm. 'O bliss,'
he cries, and longs to be transformed into every species of
energy, *to be matter !' "

Though this is an undisguised bit of imaginative writing,
it undoubtedly expresses a feeling toward "the physical
basis of life" that in essence is no fiction. Many, perhaps
most, educated persons know its meaning in some degree
from personal experience. Whence this ravishment .^^ Justi-
fication for approacliing the protoplasm question from tliis
direction is found in the belief that the validity of what is
generally held to be strictly scientific observation and gen-
eralization is to some extent at stake.

Were Purkinje, Dujardin, von Mohl, Cohn, Schultze, and
the other discoverers of protoplasm thrown into any such
state of mind by what they saw? Not so far as any one
knows. Yet I do not for an instant believe these observers
were less sensitive to the deeper meanings of the phenomena
of organic beings than have been other persons, scientific
and non-scientific, who more recently have been affected much

120

The Organism and its Protoplasm 121

as St. Anthony was, on seeing or even hearing about proto-
plasm. Particularly may we believe Max Schultze, chief
among the pioneers in this realm, was not thus defective,
for we have explicit information that he was an artist as
w^ell as a scientist, and of a highly imaginative, sensitive
nature.^

Responsibility for the Mystification of Protoplasm

Great as was Huxley's service in enlightening the rank
and file of English-speaking people concerning matters bio-
logical,. I believe what he did for protoplasm in this way
by his renowned address, "On the Physical Basis of Life,"
he did partly at the cost of "making a Magic," as Kipling
would say, of protoplasm.

A soberly scientific discussion of protoplasm cannot pos-
sibly ignore the fact that in the light of the extensive exact
knowledge now in our possession, at least one excellent biol-
ogist has believed that it would be advantageous to give up
the word "protoplasm" altogether, so far as technical biol-
ogy is concerned," because at the present time it promotes
confusion rather than clearness of thought. And even those
who do not hold so extreme a view about the value of the
term, still admit that "on many sides the word is used in
different ways." For Max Schultze, to whose writings the
legitimate protoplasm doctrine probably owes more than to
any other one of the pioneers, the word had connected with
it a "quite definite conception." ^ Without taking grounds
one way or the other on the question of whether it is or
is not desirable to abandon the word, we will look at what
came to pass both as concerns concrete knowledge and in-
terpretation of the theory of protoplasm between 1861,
when Schultze wrote the phrase just quoted, and 1912,
when O. Hertwig last defended the right of the teiTn to exist
even though used in many different senses ; for by so doing

122 The Unity of the Organism

we shall come upon that which, to a large extent, has de-
termined the present writer's attitude toward protoplasm.

To begin with, there can be no doubt that, historically
considered, "protoplasm is a biological conception," as O.
Hertwig insists.^ Furthermore, equally certain is it that
when so considered it is a term of descriptive biology pure
and simple. The discoverers of protoplasm were engaged
in the enterprise of describing and comparing the minute
structure of animals and plants, no less avowedly than the
discoverers of the capillaries of the blood system were en-
gaged in the same enterprise. They were telling what they
saw under their microscopes and were drawing conclusions
from their observations. Even the titles of many of the
foundational memoirs of the protoplasm theory show this.

On the plant side, Corti (1772) was describing what he
saw in the interior of the living twigs of Chara; Meyen
(1827) what he could see in the fresh leaves of water-celery
{V allesnaria) ; Robert Brown (1831) what the living hairs
of the still higher plant Tradescantia revealed to him, and
so on. Similarly from the account left by Rosel V. Rosen-
hof (1755) of the examination of his "Proteus animalcule"
we know he had an amoeba under his microscope and was
studying it as he had numerous other organisms, low and
high, to find out how it was constituted. It was what seemed
to Dujardin (1855) the resemblance of the soft, living mate-
rial of the foraminifera examined by him, to the flesh of
liigher animals that made him propose the name sarcode for
this material. Finally, to mention no others of the many
whose observations contributed to the upbuilding of the
science of microscopic anatomy, it was Max Schultze's exam-
ination of the minute structure of a great range of animals
and animal tissues, from amoebae and the foraminiferae to
the muscles and retinas of the 'higher vertebrates, that fur-
nished the raw materials for his splendid inductions.

If we inquire how a strictly objective discovery concern-

The Orgaiiiam and its Pi'ofoplnsm 123

ing the structure of organic beings sliould have become
enveloped in so much sentimental, half-mystical interest, one
large element in the answer soon comes into view : it is due to
Huxley's address. Undoubtedly what contributed most,
historically, to the fame of this discourse was its populariza-
tion of the conception that life has, in deepest reality, a
physical basis. Both its good fame and bad fame have
rested largely on this.

I want to make it entirely clear that, important as this
aspect of the matter is, there is another aspect very dif-
ferent from this and almost as important, with which alone
we are concerned in this section. I refer to the conception,
not definitely expressed by the phrase, but obviously implied
in it as used both by Huxley and by nearly everybody since,
that "all life is one," and that the "seat" of it is the single
wonderful substance, protoplasm. Huxley's essay abounds
in sentences and phrases expressive of this notion: "Beast
and fowl, reptile and fish, mollusk, worm and polype, are all
composed of structural units of the same character, namely,
masses of protoplasm with a nucleus." ^ "With such qual-
ifications as arise out of the last-mentioned fact [the chlo-
rophyll function of green plants] it may be truly said that
the acts of all living things are fundamentally one." ^
"Hence it appears to be a matter of no great moment what
animal, or what plant, I lay under contribution for proto-
plasm [for food], and the fact speaks volumes for the
general identity of that substance in all living beings." "

Conception of Animal S arc ode and Plant Protoplasm as

''Identical Stuffs''

Since Huxley spoke (how far because he spoke it is im-
possible to say definitely) this notion has become a dogma,
having all the objectionableness of all dogma in science.
"Subsequently, Max Schultze and de Bary proved, after

124 The Umty of the Organism

most careful investigation, that the protoplasm and the
s arc ode of the lowest organisms are identical." ^ "However,
Max Schultze in particular . . . produced incontrovertible
evidence that the protoplasm of plants and animals and the
sarcode of the lowest organisms are identical stuffs." ^ "As
the culmination of a long period of work. Max Schultze, in
1861, placed the conception of the identity between animal
sarcode and vegetable protoplasm upon an unassailable
basis, and therefore he has received the title of 'the father
of biology.' " ^ "Protoplasm, the physical basis of life,
the living part of every living being, and essentially the
same in its general properties and functions in all. . . ." ^'^^

These quotations, picked up at random, will perhaps suf-
fice to illustrate the wide prevalence of the view. But though
widely held, acquiescence to it is by no means universal and
whole-hearted, judging from a considerable number of ex-
pressions that might be cited.

This not being the place to present in detail the facts and
arguments which make the conception of the absolute iden-
tity of all protoplasm untenable, I shall do no more than
put this question to those biologists who subscribe to the
creed : In the liglit of what we now know about the reactions
of the blood of animals of different genera and even species
to one another, and about the chemical composition of the
nitrogen-containing substances of tissues and elements in
different groups of organisms, if the protoplasm of a dog,
say, could be wholl}^ removed, and tliat of a fish or even a
tree could be substituted, would the dog continue to be the
same dog, and none the worse for the change? No biologist
untrammeled by speculative considerations will hesitate to
answer this negatively, unless, indeed, it seems too ridiculous
a question to deserve serious treatment. Yet if the "con-
ception of the identity between animal sarcode and vegetable
protoplasm" is warranted by what nature actually presents
to us, the answer would certainly have to be diametrically

The Organism and its Protoplasm 125

the opposite ; that is, it would liavc to be to the effect that
a dog would be strictly himself and as well off with a tree's
])rotoplasm as with his own sarcode.

But the particular point I want to bring out Is that, tak-
ing the utterances of not merely the father but the fathers
of modern biology at their maturest and best, one finds
that not only did they not teach the identity of protoplasm
in all living beings, but tluit what they did teach was some-
thing very different. Ferdinand Cohn, for example, said of
the protoplasm which he saw escaping through the cell-wall
of the alga studied by him, "if not identical" with animal
sarcode, it "must be at any rate in the highest degree anal-
ogous" to it. ^^

Max Scliultze''s Actual Teachings as to Protoplasm and

Sarcode

In 1861, after a great many trustworthy observations
had been made in widely separated portions of the organic
realm, of substances so closely resembling one another, came
Max Schultze with the essay which gained for him the widely
recognized title "the father of modern biology." Exactly
what did Schultze aim at in this essay .^ He was primarily
concerned with the nature of the cell and not of the jiroto-
plasm. The title chosen indicates this definitely enough :
"Concerning muscle corpuscles and that which has been
named a Cell." What he undertook was to dispose of the
then prevalent doctrine that the cell-wall is the most essen-
tial part of the cell, by proving that the body itself, not
the skin or membrane of the cell. Is the really important
thing; and partly by showing that even in cells having a dis-
tinct membrane, what is contained within it is similar to the
bodies of non-membranous cells and is the really active,
living part of the cell. His definition, "A cell is a little mass
of protoplasm In the interior of which lies a nucleus" ^^ epit-

126 The Unity of the Organism

omizes his results so far as concerns his understanding of
the nature of the cell. But while Schultze's central aim in
his essay was clearly to answer his own question, "Was is
das Wichtigste an einer Zelle?" the nature of that which is
the "Wichtigste" concerned him greatly although seconda-
rily; and for the topic now occupying us, the author's con-
clusions under this head are of the utmost interest.

(«) Cell Nucleus Distinct from Protoplasm But Both
Nucleus and Protoplasm Essential to Life of Cell

In the first place, it cannot be too strongly emphasized
that Schultze did not consider the cell nucleus to be proto-
plasm in any sense: "To the conception of a cell there be-
long two kinds [of things] a nucleus and protoplasm, and
both must be division products of corresponding parts of
another cell. Both constituents are equally important. A
disappearance of one, like that of the other, destroys the
conception of the cell." ^^

This unqualified recognition of nucleus and protoplasm as
"equally important" appears over and over again in the
essay, so even from this point of view it is obvious that
Schultze could not have subscribed to the conception that
"protoplasm is the physical basis of life." For him proto-
plasm could be no more this basis than the nucleus, and the
nucleus was not protoplasm. The expression which comes
nearer than anything else in the essay to the Huxleyan
notion reads: "The cell leads an exclusive (abgeschlossenes)
life, as one may say, the bearer of which is again preem-
inently the protoplasm, but there falls to the nucleus also
a role at least as significant although as yet not more defi-
nitely specifiable." ^*

This seeming ascription to the protoplasm of the place
of first importance in the life of the cell in no way contra-
dicts the conception of correlative essentiality of tlie nucleus-

The Organism unil its Proioplasm 127

But the most vital })oInt at wliicli the teachings of the
essay are contravened by the dogma that protoplasm is the
physical basis of life ; that is, that "all life is one" and that
its basis, protoplasm, is "essentially identical" in all living
beings, involves quite another matter than that of the rela-
tion between nucleus and protoplasm. That what Schultze
actually says comes far from implying such identity I shall
now point out. The crucial part of his discussion of the
relation between plant protoplasm and animal sarcode is
introduced by a brief reference to his studies, previously
published, on rhizopods. This reference he thinks important
as a starting point for the comparison, in that the rhizo-
pods furnish a solution to the "question of what in reality
the unfonned contractile substance of the Protozoa is."
He remarks that Sarcode, brought into prominence by Du-
jardin, had become discredited because given too wide and
indefinite an application. The term as used by Dujardin
was intended to apply to a "contractile substance which
can not be resolved into cells and which does not contain
other contractile form-elements, as fibers and so on." ^^ But,
Schultze contends, a substance of this sort is exactly what
we find the protoplasm of cells to be, and supports his con-
tention by instancing the contents of many plant and animal
cells, especially where, as in the cells of the hairs of Trades-
cantia, protoplasmic movements within the cell can be wit-
nessed. Concerning the substance of these cells, he says
there can hardly be a doubt that "we have to do here with
a contractile substance in the same sense as it constitutes
the body of many rhizopods." ^^ Since, then, Schultze rea-
sons, the term Sarcode was employed originally to designate
a substance which is now brought into the same category as
Protoplasm, "Sarcode" should be dropped.

128 The Unity of the Organism

(b) Recognized Common Attributes But Not Identity of

Protoplasm in All Organisms

It is clear that Schultze's central purpose was to com-
pare the contents of cells from widely different organisms
for the purpose of showing that as concerns some attributes
of these contents, that of contractility being foremost, the
substances agree with one another. We shall do well to be
attentive to the language in which this is expressed. As
to the protoplasmic movements within the hairs of Trades-
cantia and in the bodies of many rhizopods there can be no
doubt that we have to do with "contractile substance" "i?i
the same sense.^' For the point I wish to make I transfer
the emphasis from where the author placed it, namely on
"contractile substance," to "in the same sense." To affirm
or even to imply (neither of which the author's words do)
that the substances of two or more cells are the same in so
far as they are contractile, is very different from saying
that the substances are the "same" or "identical." And look
closely at another sentence: "The proofs for the relation-
ship of both substances have only multiplied by my own ob-
servations directed at this point." Note that a relation
between at least two substances, not a single substance, nor
yet two substances which are identical, is here talked about.

That there are other attributes than that of contractility
in which these substances agree is made sufficiently clear, and
it is on these attributes-in-common that the author bases
his proposal to attach to the word "proto))lasm" an "en-
tirely definite conception," and have it displace the word
"sarcode," to which, he says, no such conception has been
attached. But that the attributes-in-common possessed by
the protoplasm of different organisms comprehend all the
attributes of protoplasm, Schultze neither says nor implies.
On the contrary, several facts and arguments on which he
lays no little emphasis ought, I believe, to be interpreted as

The Organism and its Protoplasm 129

meaning that he conceived protoplasm to be essentially dif-
ferent in different organisms as concerns some of its at-
tributes. For example, after speaking of the differences
he had observed in two species of rhizopods of the same
genus, Gromia oviformls and G. Dujardinia, he says, "I
bring this forward only in order to point out in indubitable
cases of naked protoplasm differences again in movement,
consistency, and tendency to fuse with like substances with
which it comes into contact, upon which differences we come
again in the naked cells of the tissues of higher animals."
The immediate point Schultze was aiming to establish here
was the indi^^duality, in the sense of presers^ation of iden-
tity, of the protoplasmic mass which he was contending to be
the essential thing in the cell, without the presence of a
membrane or any sort of limiting outer la3'er to insure that
individuality ; so it is only secondarily that his argument
touches upon the attributes of differentiation of the proto-
plasm itself as between different cells. Nevertheless his in-
sistence in several connections on the differences, particu-
larly in consistency and resistance of the protoplasm, surely
bears strongly in this direction. I believe, then, enough has
been said to show that the conception of protoplasm held
by the "father of modern biology" gives no warrant for the
Huxleyan and more recent conception of the essential iden-
tity of the protoplasm in all organic beings.

Ernst Brucke''s Conception of the Cell as an Organism

Another essay recognized as constituting part of the
classical literature of modern biology is Ernst Briicke's
"Die Elementarorganismen." This essay is likewise particu-
larly important for our enterprise, though in a considerably
different way from the one just examined. Although
Briicke's labors lay so largely in the same field with those
of Schultze, and although he was familiar with his con-

130 The Unity of the Organism

frere's writings, significantly enough the theses he upheld in
this essay led him to regard somewhat lightly Schultze's
leading contention, namely, for the importance of the cell-
contents, protoplasm and nucleus, as against the cell-mem-
brane. That the cell should be regarded as an organism
was, as is well known, what Briicke undertook to show, and
his motive should be distinctly recognized. He was working
in the interest of observational and descriptive histology and
physiology. Nothing in this essay, at least, indicates that
he was particularly interested in the broader implications
of his main thesis, and there is much, as we shall presently
see, to show that he was decidedly wary of "ultimate ques-
tions."

Tlie very word "organism" implies organization, and
organization implies some thing organized ; something, that
is, composed of parts a number of which, at least, are in-
dispensable and correlated with one another. An organism,
then, or an organized thing, and a thing of ultimate sim-
plicity, are tenns not only contradictory but are mutually
annihilative of meaning. Briicke does not say this in just
this language, but his whole argument is a setting forth of
the idea in a concrete, particular case, namely that of the
cell. After calling attention to the similarity of the cells
to the organism in various attributes, as that of growth
by ingestion of foreign material, movement, change of form,
response to stimulation, and so on, and after reminding us
further of the fact that organisms are composed of parts
which we call organs and systems of the body, he says, "We
can hardly think otherwise than tliat in the cell also the
different activities proceed from differently constructed
parts." ^^

Going further with this idea, he writes : "We naturally
do not expect that the organs and systems repeat themselves
as we find them in the human organism taken in its entirety.
We know this is no more the case even in the lower animals.

Tlie Organism and its Protoplasm 131

\Vc know that witli reduction in dimensions nature changes
the means bj which the energies of the inorganic world are
made serviceable in the organism. But with the exception of
the differences conditioned by this fact, and with the ex-
ception of tlie less number of constituting parts, we have
no right to liold one of these smaller organisms as less
ingeniously constructed than one of another or greater di-
mensions, and this consciousness we ought to bring not only
to the investigation of the smallest animals, but likewise to
the investigation of plant and animal cells. We may always
see in the cell a small animal body, and ought never to
lose sight of the analogies which exist between it and the
smallest animal forms." ^^

Characteristic Organization in All Cells

But it is in connection with the problem of the more de-
tailed structure of all parts of the cell, membrane, nucleus,
and cell-body alike, that this investigator's conclusions and
attitude of mind are most fully revealed, his great point
being that there must be far more of organization in the
cell than microscopes reach. "What right have we to be-
lieve," he says, "that in our scheme we have exhausted the
organization of the cell.^ Is it a ground for such an as-
sumption that we can perceive no further details in the
relatively giant retinal image given us by our present high
magnifications? . . . Shall we conceal from ourselves the
fact that many circumstances limit the field of our mi-
croscopical determination?" ^^

In \'iew of the fact that later speculative biologists have
appealed to Briicke's contention that there must be cell or-
ganization beyond that revealed by the microscopes, in sup-
port of their fancied "ultimate biological units," it should
be emphatically pointed out that not only does Briicke's ar-
gument not give passive sanction to such hypotheses, but

132 The Unity of the Organism

rightly interpreted it opposes them. He does indeed main-
tain that molecular structure als known to the chemist
can not be the only kind which eludes observation. "These
molecules," he says, are "not merely building stones placed
one beside the other in a simple fashion, but are united to-
gether in an ingenious {kanstreich) living organization." ^'^

And referring back to the paragraph quoted, in which
the differences in structure between small and large or-
ganisms are dwelt upon, we find an unmistakable indica-
tion that the mode of conceiving, as one may say, which
Briicke would hold, might be legitimately applied to the
ultramicroscopic structure of org^yiisms : "We may always
see in the cell a small animal body and ought never to lose
sight of the analogies which exist between it and the smallest
animal forms." -^ That is, each living cell at any and every
moment has organization of its own beyond what we can see
with the microscope, the organization being analogous to
that which exists in the smaller animals. No vagaries here
about an organization in one cell (a germ cell) which rep-
resents the visible organization of some other cell-organism
developed from that cell.

In another passage Briicke sounds a warning about theo-
rizing in this domain of biology which, had it always been
heeded, would have prevented much wandering about in a
morass of speculation. "Desirable as it is," he says, "al-
ways to hold rigorously to immediate observation, equally
necessary is it not to close the spiritual eye to that which
is inaccessible to observation, so that we overprize the work
of our microscopical determinations and with the help of
final words {Schlagworter) — cell-membrane, cell-contents
and cell-nucleus, erect physiological doctrines which a fu-
ture generation may refuse recognition." ^^

To be sure, the author was aiming in this at doctrinal
perils considerably different from those of recent "repre-
sentative biological units," but the essence of bis warning

The Organism and its Protoplasm 133

is applicable in the one case as in the other. He would have
no pseudo-scientific explanations, whether hidden behind
'^ Schlagworter'" or entities of the pure imagination, given
a semblance of objective reality by being connected with
actual objects. One of the great merits of Briicke's attitude
toward the problem of the constituents of the living beings
which lie beyond the reach of direct observation should be
specially pointed out, though this is not the place to speak
of it in detail. From several of his statements, but par-
ticularly from that about the analogies between the cell and
the smallest animals, we may infer that he had a genuine
appreciation of the distinction there is between the concep-
tion that there must be some sort of organization beyond
what the microscope reveals, and a conception of what the
specific nature of that organization is in particular cases.
So a critical examination of Briicke's fundamental essay
reveals the fact that though starting from a quite different
standpoint from that of Max Schultze it contains as little
as does Schultze's essay to support belief in the identity
of protoplasm in all living things.

Results of Later Description and Classification of Cell

Substances

The question still to be considered is whether or not the
discoveries made since the pioneer era have furnished, by
the actual study of protoplasm, more support for the be-
lief in such identity. I do not believe any candidly critical
student will maintain that they have. On the contrary I
believe such a student will recognize that the indubitable
tendency of the evidence is toward the opposite conclusion ;
namely, that the protoplasm not only of all organisms, but
of many different parts of the same organism, is to some
extent different.

That the observational knowledge of the substances con-

134 The Unity of the Organum

stituting living organisms has been vastly increased since
Schultze and Briicke wrote, hardly needs affirmation. This
greatl}^ augmented store of knowledge may well be regarded
for a moment in the light of the circmiistances referred to
some pages back. One outcome of later work has been a
serious questioning of the scientific desirability of longer
retaining the word "protoplasm." To , be sure, this ques-
tion was not raised primaril^^ because of interpretations of
the substance of the cells of different organisms, but rather
because of interpretations placed upon different substances
in the same cell. Strasburger, who seems to have been the
first to depart from Schultze's sharp distinction between the
protoplasm of the cell and the nucleus, was led to this by
determinations made largely by himself, which had accu-
mulated during the two decades of research since Schultze
wrote, that the nucleus is by no means the simple, homo-
geneous thing it appeared to the earlier investigators, but
has itself an elaborate organization, portions of which re-
semble protoplasm in many respects.

Not without significance is the fact that beginning about
the same time the custom has grown up of using the term
plasm or plasma instead of protoplasm. It is not unusual
to regard these words as exactly synonymous, and to sup-
pose the only advantage in plasma is its brevity. Obviously
the term is more non-committal in meaning than is proto-
plasm, the idea of a ^^first formed substance" being undoubt-
edly very different from that of merely a ''formed sub-
stance." But Strasburger's proposal went further than
merely to name the whole cell substance protoplasm. He
proposed to replace it by cytoplasm for that part of the
cell to which alone Schultze had applied the word proto-
plasm, and to call the portion in tlie nucleus micleoplasm.
This last, being a mongrel word, was soon replaced by
haryoplasm.

In other words, the change in the scope and meaning of

The Organism and its Protoplasm 135

terms introduced the really more significant thing, namely,
that of a definite effort toward a scientific classification
of the constituents of the cell, this being based upon and
necessitated by tlie fuller and exacter descriptions of the
cell that had been reached.

This brings us to wliere we can formulate more closely
the question now before us : Do the descriptions fully agreed
upon at the present day, of the substances entering into
the constitution of living beings, warrant the belief that a
single substance, under whatever name, is the basis of life,
and is identical for all organisms? No one should fail to
notice the two parts of the question: (1) Is there a single
substance which is the basis of the whole life of any one
organism? (2) If this were answered affirmatively, would
that substance be identical for all organisms?

(a) Cytoplasm and Karyoplasm Differentiated Areas of a

Common Basic Substance

Several competent investigators in this department of
biology have summarized both the observational and the
interpretative knowledge now in our possession. A liberal
appeal to these summaries will furnish a direct and sure
answer to the first part of the question, and an indirect
though hardh' less sure answer to the second part. To be-
gin with, I quote from Wilson, the first point to be brought
out being that of the relation between the nucleus and the
rest of the cell. "Careful study of the nucleus," he says,
"during all its phases gives, however, reason to believe that
its structural basis is similar to that of the cell-body ; and
that during the course of cell-division, when the nuclear
membrane usually disappears, cytoplasm and karyoplasm
come into direct continuity. Even in the resting cell there
is good evidence that both the intranuclear and the extra-
nuclear material ma}^ be structurally continuous with the

136 The Unity of the Organism

nuclear membrane. . . . For these and other reasons the
terms 'nucleus' and 'cell-body' should probably be regarded
as only topographical expressions denoting two differen-
tiated areas in a common structural basis. The terms kary-
oplasm and cytoplasm possess, however, a specific signif-
icance owing to the fact that there is on the whole a definite
chemical contrast between the nuclear substance and that of
the cell-body. . . .

"Both morphologically and physiologically the differen-
tiation of the active cell-substance into nucleus and cell-body
must be regarded as a fundamental character of the cell
because of its universal . . . occurrence, and because there
is reason to believe that it is in some manner an expression
of the dual aspect of the fundamental process of metabolism,
consti-uctive and destructive, that lies at the basis of cell
hfe." 22

So far as I am able to make out, authorities are in essen-
tial agreement as concerns the directly observational part
of this statement touching the relation between nucleus and
cell-body. The general conclusion is that, keeping an eye
on the actual structure of the cell and ignoring for the
moment the system of naming applied to the different parts,
Schultze and Strasburger were both right ; Schultze in hold-
ing that there is something fundamental in the distinction
between nucleus and cell-body, and Strasburger in holding
tliat there is something fundamental in the kinship between
the two. Interpretatively, therefore, the question resolves
itself into one of naming and classifying what is observed,
and there can be no doubt, as Wilson and a majority of
recent authors liave recognized, not only of the convenience
but of the scientific soundness of using the term plasm for
the living substance of the cell as a whole, and then des-
ignating the kindred but yet different kinds of plasm by
the terms karyo plasm and cytoplasm.

The Organism and its Protoplasm 137

(b) Details of Cytoplasmic Structure

Concerning the details of structure of these two main
classes of cell material, Wilson writes: "As ordinarily seen
under moderate powers of the microscope, protoplasm ap-
pears as a more or less vague granular substance which
shows as a rule no definite structure. More precise exam-
ination under high powers, especially after treatment with
suitable fixing and stahiing reagents, often reveals a highly
complex structure in both nucleus and cytoplasm. Since
the fundamental activities of protoplasm are everywhere of
the same nature, investigators have naturally sought to
discover a corresponding fundamental morphological or-
ganization common to all forms of protoplasm and under-
lying all its special modifications. Up to the present time,
however, these attempts have not resulted in any con-
sensus of opinion as to whether such a common organization
exists. In many forms of protoplasm, both in life and
after fixation by reagents, the basis of the structure is a
more or less regular framework or meshwork, consisting of
at least two substances. One of these forms the substance
of the meshwork proper: the other, often called the grownd-
suhstance, (also cell-sap, enchylema, hyaloplasma, parami-
tome, interfilar substance, etc.), occupies the intervening
spaces. To these two elements must be added minute, deep-
ly-staining granides or 'microsomes' scattered along the
branches of the meshwork, sometimes quite irregularly, some-
times with such regularity that the meshwork seems to be
built of them. Besides the foregoing three elements, which
we may provisionally regard as constituting the active sub-
stance, the protoplasm almost invariably contains various
passive or metaplastic substance in the form of larger gran-
ules, drops of liquid, crystalloid bodies, and the like. These
bodies, which usually He in the spaces of the meshwork, are
often difficult to distinguish from the microsomes lying in

138 The Unity of the Organism

the meshwork proper — indeed, it is by no means certain
tliat any adequate ground of distinction exists." ^'"^

(c) Three Main Theories of the Structure of Protoplasm

Wilson then sets forth in general terms the three lead-
ing interpretational views of the nature of what is here
described ; that is, the well-known reticular or filar theory,
the alveolar theory, and the granular theory. It may not
be superfluous to state briefly what each of these theories
is. The reticular theory interprets what is seen in the
protoplasm in its simplest form, as a network of actual fi-
bers which branch and anastomose with one another so as
to make, according to the familiar comparison, something
like the network of a sponge, the spaces within the retic-
ulum being filled by the fluid or semi-fluid portions of the
protoplasm. This view holds that the granules, supposed
by the older observers to be essential constituents of the
protoplasm, are the angles where the threads join, the
threads seen end-on, and in some cases true granules at-
tached to the threads. The alveolar theor}', proposed and
defended with great detail of observation and argument by
O. Butschli, compares the protoplasm with foam rather
than with a sponge. It contends that protoplasm consists
of separate, closely crowded minute drops of a liquid alve-
olar substance suspended in a continuous interalveolar sub-
stance, likewise liquid, but of diff'erent nature. According
to this interpretation what are taken by the reticular
theory to be fibers are the walls of the alveoli, there being
in reality no fibers present. The granular theory holds
that granules of various sizes and nature are the fundamen-
tal constituents of protoplasm, the fluid and the semi-fluid
parts, as also the fibers whenever present, being of sec-
ondary significance.

The (Jrcjaifism cnuj its Protopinsjn 139

(d) ''No Unwersal Formula for Protoplasmic Structure'*

Finallj^ summing up his own conclusions regarding these
tliree theories, Wilson says: "]\Iy own long-continued stud-
ies on various forms of protoplasm have likewise led to the
conclusion that no universal formula for protoplasmic struc-
ture can be given. ... It is impossible to resist the evi-
dence that fibrillar and granular as well as alveolar struc-
tures are of wide occurrence ; and while each may be char-
acteristic of certain kinds of cells or of certain physiological
conditions, none is common to all forms of protoplasm. If
this position be well groimded, we must admit that the
attempt to find in visible protoplasmic structure any ade-
quate insight into its fundamental modes of physiological
activity has thus far proved fruitless. We must rather
seek the source of these activities in the ultramicroscopical
organization, accepting the probability that apparently
homogeneous protoplasm is a complex mixture of substances
which may assume various forms of visible structure accord-
ing to its modes of activity." -^

And so we have this excellent authority's answer to the
first part of the question above formulated : The knowledge
we now possess derived from observational studies on the
minute structure of organic beings does not warrant the be-
lief that there is a single substance which is the basis of the
whole life of any one organism.

But if the facts do not warrant such belief what possible
ground is there for the doctrine of the identity of proto-
plasm in all organic beings? Were there no other evidence
against it than this drawn from the microscopical morphol-
ogy of organisms, here alone is sufficient evidence to banish
the dogina completely and forever from scientific biology.
But as we see in other sections of this treatise, particularly
those on the organism and its chemical compounds, there
are even more compelling e^adences against the doctrine than
those here passed in review.

140 The Unity of the Organism

Preliminary Remarks on the Bearing of Physical Chemistry

on th£ Protoplasm Doctrine

The theorj^ of protoplasm as the living substance, as
though there were a single substance identical in all or-
ganisms and in all parts of the same organism, has passed
into a new and peculiarly subtle stage during the last two
or three decades. This has been one of the results of the
application which was sure to be made of physical chemistry
to biological phenomena.

An understanding of what is implied by this will be
facilitated by reflecting on some of the most obvious dif-
ferences between physics and chemistry, and on what phys-
ical chemistry as contrasted with chemistry pure and
simple is ; that is, chemistry as it was prior to the rise of
physical chemistry. But since we are invading a perilous
realm, one in which diverse and strenuously contested views
prevail, we must confine ourselves to what is most obvious.

That that vast series of transformations of natural sub-
stances which occur when two or more of the substances
come together under certain conditions, so profound that
the new substance is wholly different from the originals, are
real objective phenomena, and are the bases of the science
of chemistry, no one will gainsay however unqualifiedly he
may be committed to the theory that these phenomena be-
long to the domain of pliysics after all. The reality of the
transformations, and hence the reality of the discrete, in-
dividuated bodies or substances, both those entering into the
combinations and those arising from the combinations, is
what especially concerns us. Whether the combinations and
transformations are influenced by physical as contrasted
witli cliemical forces, and what names and classifications
shall be employed in dealing witli tlie phenomena, are of
very secondary importance to this discussion.

On the other hand, that there Is an almost if not quite

The Organism and its Protoplasm 141

equally vast series of phenomena presented by natural bod-
ies and substances which do not involve such combinations
and transformations and which are the basis of the great
science of modern physics, will also probably be accepted
without cavil. But tlie point to be specially noticed is that
since physics as tlius indicated is primarily concerned with
those attributes of bodies and substances which are common
to very great numbers of them, and are not only common to
them but while rendering the bodies subject to great change,
do not make them subject to complete transformation, the
discrete, the individuated bodies fall much into the back-
ground.

Physics is preeminently from its vei'y nature an individ-
ual-ignoring science. Concentrated as its attention is, on
the force of gravitation for example, or on the behavior of
light, and finding these manifested almost everywhere re-
gardless of how many kinds of bodies are concerned, it is
not surprising that the habit should be formed by persons
who devote themselves to studying these phenomena, of neg-
lecting almost entirely the bodies themselves which have
weight and emit and receive light. Then when this habitual
tendency to neglect the bodies finds encouragement by well-
reasoned hypotheses that the bodies are actually less im-
portant and real than certain essences or entities "behind"
them, the ignoring of the bodies passes easily from the realm
of habit to that of dogma, and such strange conceptions of
the "Province of Physics" as the following arise: "If further
we give the name thing to that with the objective existence
of which we are acquainted by our senses, then it follows
that in the physical universe there are only two classes of
things; to these the names Matter and Energy are given." ^^
That protoplasm, of just such a conceptual character as
we are pointing out in this chapter does not exist, would
obviously be acceptable to a physics holding such an unob-
jectificd, denatured conception of nature as that just

142 The Unifij of the Organism

quoted. If there are "only two classes of things" in the
universe, "flatter and Energy," it would follow that the
myriads of individual organisms which according to our
senses certainly seeTU to exisi^ are after all phantasms of
some sort, and those departments of science which deal with
the phantasmal individuals would have to concern them-
selves chiefly with "getting behind" the apparitions to the
two real things, the Matter and the Energy.

But even those physiologists and biologists who adopt the
physical-chemistry standpoint most unreservedly speak of
the matter of which organisms are composed as "living"
and so do not quite accept the restrictions upon them of
such a conception of the "province of ph3^sics" as that
formulated by physics itself in the quotation above given.
They seem to insist by implication that "living matter" is
a real thing, no less than are Matter and Energy. This is
very significant from our standpoint and will be exceedingly
important if finally physics, too, shall fully accept it. It
will be thus important because if biology is driven, as this
treatise holds it will be, to recognize that the individual or-
ganism, each and every one that exists or ever has existed,
is as real a thing as are any of its parts or substances, by
whatever criterion of reality science or philosophy can ap-
ply ; and if physics goes with biology in this, then will ob-
jective science as a whole be committed to a doctrine of the
universe vastly different from that which now dominates the
physico-mathematical sciences. Put into the briefest, most
concrete form possible, such a consummation would establish
the" so-called natural history, or descriptive, or "inexact"
(sic?) sciences in a place at least as secure and exalted as
that held througli the centuries in western civilization by
the mathematico-physical, the so-called exact sciences.

And we must not forget tlie important fact that physics
itself as conceived by some of its eminent devotees, occupies
no such all-inclusive, all-dominating and domineering place

The Organism and its Protoplasm 143

in the liicrarchj of the sciences as that implied by the quo-
tation given above. Thus : "Physics in the largest sense
of the word is the science of unorganized matter and the
phenomena which it manifests. These phenomena are called
physical phenomena. All the other sciences which occupy
themselves with matter, have to do with organized substance
(the biological sciences)." ^*^

The whole-hearted recognition by physics as thus con-
ceived, of matter in two fundamentally different conditions,
these giving rise to two coequal realms of science, places no
obstacles in the way of biology's bringing into clear view the
significance of individuals as natural phenomena. That
physical chemistry can be of enormous service in the inter-
pretation of living beings if only it docs not claim too much
for itself, if it recognizes physiologico-, or better bio-
chemistry, to be on a par with itself, we shall see to some
extent in later chapters.

Experimental Evidence of the Specificity of Protoplasms

Up to this point the burden of the facts and arguments
of this chapter has been in a sense negative. It has been in
opposition, merely, to the generalization that protoplasm
is one and the same thing in all organisms. Although rela-
tively few researches in microscopic comparative morphology
and embryology have been carried out with the avowed pur-
pose of discovering in how far each organism or group of
closely related organisms has its own fundamental sub-
stances, the few which have been made have yielded highly
significant results and open the gate to an alluring realm for
future exploration.

{a) Greater Fusibility Between Closely Related Species, as
in Tissue Mixtures and Grafts

The morphological investigations which will, perhaps, be
most crucial when carried far enough, are those on the fusi-

144 The Unity of the Organism

bilitj of naked protoplasm from different organisms — from
different individuals of the same and of different species.

The experiments of H. V. Wilson on the coalescence of
dissociated cells of sponges and hydroids particularly, have
blazed a seemingly very practicable manipulative path into
the subject. Wilson cuts portions of the animals into small
pieces, then squeezes these through bolting cloth. This
operation separates the tissues into small groups of cells,
and to some extent into completely isolated cells. These
cells, kept under favorable conditions, soon assemble together
into compact masses, and from the masses normal animals
frequently develop. Although Wilson has thus far been
chiefly occupied with showing that various animals are able
within their own species to rehabilitate themselves under
such conditions, he has not failed to raise the question of
how far coalescence and normal development may take place
when tissues of different species are mixed together. His
experiments under this head are far less extensive than those
on the commingling of cells from different individuals of the
same species, but are nevertheless highly instructive. In his
paper of 1907 his statement, "Unlike specific substances
(protoplasms of quite different species) do not tend to
fuse," ^^ is perhaps a somewhat more unqualified denial of
the fusibility of the protoplasms of different species ; or
stated affirmatively, a somewhat more unqualified assump-
tion of the specificity of the protoplasms of each species
than the observations presented by him in a later publication
justify.

But if this much of restriction upon his conclusions may
be necessary, there still remains evidence of the most con-
vincing sort in his results of the specific nature of the pro-
toplasm of different species. The only details he has so
far given of his negative results are contained in his report
on sponge culture to the Bureau of Fisheries. In this he
describes experiments on intermingling the tissues of Micro-

The Organism and its Protoplasm 145

ciona prolifera, witli those of Lissodendoryx carolinensis^
and M. prolifera with Stylotella heliophila. In both cases
the larger fragments were discarded, and only the cells and
small cell masses experimented with. These were thoroughly
mixed together in watch glasses by jets of water from a
pipette. "The mixture was spread evenl}^ over the bottom
of tile watch glass, and looked like a fine sediment." But
the cells of each species could be readily distinguished, those
of Lissodendoryx being greenish and those of Microciona
being briglit red (to speak of these two species). "Fusion
began, and the bottom w^as soon covered, no longer with a
continuous 'sediment' but with discrete small masses, some
red, some green. ... In general red mass fused with red
mass, and green mass with green mass. Nevertheless fusion
was also observed in some instances betw^een red and green
masses. . . . Such fusions, as the further history of the
watch glass showed, must have been temporary or the com-
bined masses soon died. For as fusion progressed and the
masses increased in size, the distinction between red and
green tissue became more evident." -^ The outcome was
that, young sponges of pure Microciona were developed but
none of Lissodendoryx, the development going no further
than the early fusion stages. Likewise in the mixture of
Microciona and Stylotella there was no fusion between the
cells of the two species nor was there a full development of
Stylotella sponges alone.

The point wherein these negative results are somewhat
less conclusive than might be wished is that neither in Lis-
sodendoryx nor Stylotella were full fledged young sponges
produced from the dissociated tissues even when these were
treated each species by itself. It may be said that a fusion
of two species could not be expected if one of them is in-
capable of fusion and development alone. Nor is this ob-
jection fully met by the fact that in one of the species at
least, Lissodendoryx, the early stages, that is the fusion

146 The Unity of the Organism

stages, do occur. To make the case quite satisfactory fail-
ure to fuse ought to be shown between species both of which
are able, and about equally able, to develop into typical
animals of their own species.

But the evidence of specificity of the protoplasm of the
different species indicated by the experiments is by no means
restricted to the nonfusibility of the cells of the several ani-
mals. Quite as conclusive is difference in behavior of the
various preparations. Although Wilson does not go into
this particularly, his experiences show that the tissues of
Microciona produce young sponges considerably more read-
ily than do those of the other species when treated in exactly
the same manner. As to the relative viability and develop-
ability of dissociated cells of Lissodendoryx and Stylotella
the descriptions are not full enough to enable one to decide.
A comparison of the species on the basis of quantitative
determinations of both the extent of development and the
conditions of the water under which the development takes
place would probably settle this and would be highly in-
structive.

Another investigator, Karl Miiller, reports that the dis-
sociated cells of individuals of different species are able to
fuse together but that the fusion masses "never regenerate
to small sponges." No details are given under this head,
but are promised in a later publication.

Obviously the fusibility or non-fusibility of isolated tis-
sues as brought out by experiments of this kind are phe-
nomena close of kin with those of the degree of compati-
bility of grafts in the ordinary sense with the "stock" upon
which they are grafted. It was mentioned in another con-
nection that we now have sufficient information about graft-
ing in animals to show that much the same rules hold here
as among plants.

Morgan reviews the work that has been done in animal
grafting, and sums up the results on the congeniality be-

The Organism and its Protoplasm 147

twecii different kinds as follows: "The general statement
may be made for both cases [grafting and fertilization] that
closely related species combine more readily than those far
a])art, i.e., the results are more successful for unions be-
tween closely 'related' forms than between distantly 'related'
forms. Certain exceptions exist, however, in both direc-
tions." ^^

But while the fusibility or non-fusibility of the tissues of
diff'erent animals as revealed by Wilson's methods are phe-
nomena closely related to the compatibility or non-compati-
bility of scion and stock in plant grafting, the former would
seem to be, so far as the methods can be emploj^ed, a con-
siderably better test of the specificity of the protoplasms
of different individuals and species. This is so because by
comminuting the animals, as Wilson does, and then thor-
oughly mixing the elements, every part and kind of substance
of the one may be supposed to be brought into contact with
every part and kind of substance of the other, whereas in
grafting only a relatively small portion of the scion can
actually touch the stock, and generally speaking only in
such manner that the corresponding kinds of substance i.e.,
corresponding tissues, come together. From this it may well
be, that there is really more specificity of substances in the
ordinary graft than might at first thought be inferred from
the perfection of the union. Actual fusion may occur only
between some substances of each party to the union, and
the general life and activities of the graft may be kept up
through its ordinary metabolic processes, it, however, using
as food to some extent, substances received from its host,
instead of wholly from the outside world.

Indeed some such interpretation as this appears to be
necessitated by the strict maintenance of type of both
graft and host. From this standpoint a successfully grafted
individual plant or animal might be defined as a partnership
in which each partner while maintaining most of its own

148 The Unity of the Organism

former individuality still supplies to the others certain es-
sential food substances from its own body and activities es-
sential to the other. The relation between the two organ-
isms which are grafted together seems similar in important
respects to the relation between two organisms living to-
gether symbiotically. In fact, a graft combination might
be spoken of as an artificial symbiosis. On the whole, then,
the morphologico-physiological study of the ability of or-
ganisms to fuse together bodily points unmistakably to the
belief that different kinds of organisms must contain in their
make-up certain fundamental substances that are different
as well as certain others that are very much alike if not
quite identical. In other words such studies furnish no
warrant for the conception of a physical basis of life identi-
cal in all living beings.

{h) Protoplasms, Not Protoplasm, Must Be the Form of the

Protoplasmic Conception

Studies of this kind show that if the term protoplasm is
to have any scientific usefulness it must be used in the plural
— protoplasms — and so must be subject to the practices
and principles of biological description and classification in
the same way that all other biological entities are, and the
great and ever-increasing munber of elements now known
with more or less definiteness as entering into the makeup
of living substance must, I believe, be looked at in this light
by all departments of biology as w^ell as by natural history.
Protoplasms are the substances of which individual or-
ganisms are composed, so the protoplasms as well as the
organisms must be individuated.

To set forth the facts and reasonings upon which such a
conception of protoplasm must rest is one of the foremost
objects of several of the discussions in this treatise. Those
on the organism and its chemistry, and the organism and its
cells, are especially dedicated to this end.

The Organism and its Protoplasm

149

REFERENCE INDEX

1. Locy 273 16.

2. Hertwig, O. ('95) 12 17.

3. Schultze 17 18.

4. Hertwig, O. ('12) 12 19.

5. Huxley ('68) 140 20.

6. Huxley ('68) 138 21.

7. Huxley ('68) 148 22.

8. Hertwig, O. ('95) 7 23.

9. Hertwig, O. ('12) 8 24.

1 0. Needham 88 25.

11. Geddes 829

12. Schultze 11

13. Schultze 23 28.

14. Schultze 11 29.

15. Schultze 16

Schultze ir

Briickc 387

Briicke 383

Brucke 386

Briicke 387

Brucke 385

22

23

27

1

26. Chwolson 1-2

27.

Wilson, E. B.

Wilson, E. B.

Wilson, E. . B.

Watson

('00).
('00) .
('00).

Wilson, H. V.
Wilson, H. V.

('07)
('10).

257
14

Morgan ('07) 298

Chapter VI

THE ORGANISM AND ITS CELLS

What the Cell-Theory Is, Viewed Historically and

Substantiiyelfj

(a) Importance and General Character of the Theory

THE cell-thcorj seems to some biologists second to the
evolution theory alone in its importance to biological
science. This may be too high an appraisement ; but beyond
question it is and ever will be one of the most influential
generalizations yet reached by the science.

(h) Various Forms of the Theory as Currently Held

The views of tlie cell incident to our general standpoint
necessitate a critical consideration of the theory. What,
exactly, is included in it ? Does it contain more than one
crucial idea? If so are all equally well grounded in observa-
tion? Clearly it has differed considerably in both scope and
specific meanings at different times and for different authors.
The formulation of it by Theodor Schwann, generally re-
garded as its founder, undoubtedl}^ left it open to a con-
siderable range of interpretation. Schwann says, "The
development of the proposition that there exists one gen-
eral principle for the formation of all organic productions,
and that this principle is the formation of cells as well as
the conclusion which may be drawn from this proposition,
may be comprised under the term cell-theory, using it in
its more extended signification, while, in a more limited

150

The Organism and Its Cells 151

sense, by the theory of cells we understand whatever may
be inferred from this proposition with respect to the powers
from which these phenomena result." ^

Two meanings, a broader and a narrower, are thus ex-
pressly indicated ; and the permissive phrase "whatever may
be inferred" attached to the more restricted one, points a
way to diversification of interpreting it that was sure to be
followed.

In view of the comprehensiveness of the theory as thus
initially conceived, it is surprising to find Virchow, one of the
earliest and most distinguished promoters of it, speaking
of it as pertaining to the mode of origin of cells. "This
description of the first development of cells out of free
blastema, according to which the nucleus was regarded as
preceding the formation of the cell, and playing the part of
a real cell- former (cytoblast), is the one which is usually
conciseU' designated by the name cell-theory (more ac-
curately theory of free-cell-formation)." ^

O. Hertwig's statement of the theory is as follows : "Plants
and animals, so dissimilar in external appearance, agree in
the foundation of their anatomical structure ; for both are
composed of similar elementary units mostly visible by the
aid of the microscope onl3^ According to an old theory,
now abandoned, these units are called cells, so that the doc-
trine that animals and plants consist in a similar way of
such smallest particles is designated the cell-theory." ^

But Hertwig's treatment of the cell in his earlier volume
Die Zelle, and in his later more comprehensive work,
Allgemeine BioJogie, (4th ed.), surely adds much to the
theor}' that is not hinted at in this brief definition.

The characterization of the theory by E. B. Wilson more
adequately expresses its scope as practically understood and
used by many recent biologists, including Hertwig himself.
"In its broader outlines," writes Wilson, "the nature of this
organization is now accurately determined; and the *cell-

152 The Unity of the Organism

theory,' by which it is formulated, is, therefore, no longer
of an inferential or hypothetical character, but a generalized
statement of observed fact which may be outhned as fol-
lows":— [only the baldest essentials of the outline are here
given]. (1) "In all higher forms of life, whether plants or
animals, the body may be resolved into a vast host of minute
structural units known as cells, out of which, directly or
indirectly, every part is built." (2) "Essentially the cell is a
minute mass of protoplasm," this substance being "uni-
versally recognized as the immediate substratum of all vital
activity." (3) All the cells of each individual organism are
descended by cell division from preceding cells and finally
from one single cell, the fertilized egg-cell. (4) This fer-
tilized egg-cell, which is the beginning of each individual
organism, is produced by the fusion of two cells one of
which comes from the mother, the other from the father
of the individual in question, so that "the ultimate prob-
lems of sex, fertilization, inheritance, and development are
shown to be cell-problems.^^ *

The tout ensemble of meaning and of importance of the
theory for Wilson are forced home in the very first sentence
of his excellent book : "During the half-century that has
elapsed since the enunciation of the cell-theory by Schleiden
and Schwann, in 1838-39, it has become ever more clearl}'^
apparent that the key to all ultimate biological problems
must, in last analysis, be sought in the cell." ^

A concise formulation of the theory with the expansive
meaning given it by Wilson is furnished by Locy in Biology
and its Makers. "A statement of the cell-theory at the
present time, then, must include these four conceptions:
the cell as a unit of structure, the cell as a unit of physio-
logical activity, the cell as embracing all hereditary quali-
ties within its substance, and the cell in the historical de-
velopment of the organism." ^

This expanded form of the theory of cells, held implicitly

The Organism and Its Cells 153

rather than explicitly, has brought it to pass that many
biologists seem to do most of their scientific thinking in
terms of cells. The multiform activities of "cell-life," as
a common expression has it, appear to be the final thought-
goal of such biologists. But the theory is not by any means
allowed so broad a scope by all biologists. This finds illus-
tration in the article on the theory furnished to the Dic-
tionary of Philosophy and Psychology by C. Lloyd Morgan
and E. S. Goodrich. As understood by these authorities,
the theory is, "The doctrine tliat all organisms are composed
either of individual cells (unicellular organisms) or of a
compound aggregate of cells (the higher plants and animals)
with certain cell-products ; and that every cell, no matter
how differentiated in structure or function, is derived from
a preceding cell." ^

A few good authorities, for example, Driesch, even go so
far in restricting the cell-theory to this aspect of it, and in
standing so confidently on its factual nature as to deny
that there really is now a cell-theory at all. The cellular
composition of all organisms (the unicellulars of course
excepted) is, he says, "a simple fact of observation, and I
therefore cannot agree with the common habit of giving to
this plain fact the title of cell-theory. There is nothing
theoretical in it." ^ The examination of definitions has
gone far enough to bring out several points of prime moment
for our enterprise : The cell-theory has been in the past,
and still is, understood quite differently by different biolo-
gists. In the narrower signification given it by such au-
thorities as Morgan and Goodrich, it is held to the strict
bounds of a generalization of observations on the minuter
make-up of both adult and all developmental stages of plants
and animals. Such observations, vast in range and num-
ber, have thus far found no exception to the rule that each
plant and animal body can be resolved into very small units
and products thereof, all the units in each organism being

154 The Unity of the Organism

derived by division from preceding units. These units have
so much in common both structurally and functionally that
the same name may be applied to them all. The name fixed
upon, though a bad misfit because of serious errors of obser-
vation and interpretation on the part of several early inves-
tigators, is cell.

When held down to these narrower limits, the theory
contains no express reference to heredity ; it makes no claim
to "embracing all the hereditary qualities in its substance."
Still less does it contain even by implication the notion
that the "key to all ultimate biological problems must, in
last analysis, be sought in the cell."

(c) Statement of Theory Justified by Present State of

Knowledge

I may now state categorically my view of the cell-
theory : If accepted in the broad signification given it by Wil-
son and many others, it must be recognized as consisting of
two very distinct parts. First, there is the part which ex-
presses in the generalization, no longer questioned by any
one, the cellular constitution of all organisms and the origin
of individual cells. And second, there is the vaguely hypo-
thetical part about the cells "embracing in their substance
all hereditary qualities," and for this and other reasons be-
ing the "ke}^ of all ultimate biological problems." If our dis-
cussion of "The organism and its cells" accomplishes its
aims, it will remove the vagueness of this second part of
the cell-theory, and in doing so, while questioning in no
manner any established truth which it contains, will reveal
the inadequacy of some of its central conceptions.

"The whole of an organism is as essential to the inter-
pretation of its parts as the parts are to the interpretation
of the whole." So runs the first of our fundamental prop-
ositions. Let us substitute "cells" for "parts" in this and
examine it. The organism is as essential to the interpre-

21ie Organism and Its Cells 155

tation of its cells, as the cells are to the interpretation of
the organism. A brief excursion into the liistory of the
cell-theory is essential to the discussion.

It is well known that the early workmen on the cell-
theory had quite erroneous notions of the nature of cells.
The error has, unfortunately, left its conspicuous and in-
eradicable mark on biology in the term cell. This name
was chosen from the circumstance that the first studies were
made on grown plants where the cell-wall is the most easily
observable part of the cell, so that the ctlls frequently ap-
pear like vesicles either quite empty or containing a clear
fluid or semi-fluid. Cells were closed chambers the walls of
which were the main thing, according to tliese pioneering
views. For a long time the nature, structural and func-
tional, of the contents of these chambers played only a
subordinate part. Gradually, however, from widely scat-
tered observations, partly on the simplest unicellular or-
ganisms, partly on the contents of certain simple plant cells,
and partly on the tissues of higher animals, it dawned upon
biologists that the material within the cell-wall is the main
thing, and that this material is much the same in all cells,
whether plant or animal, of low or high degree. The pro-
toplasm of Purkinje and Von Mohl, the sarcode of Dujardin,
the "cell sap" of Corti and Treviranus, and the "plant
nmcilage" of Schleiden, were all brought together because
of their close resemblance and designated by a single name.
On account of the seeming simplicity of this material and
tlie undoubted dependence of life phenomena upon it, pro-
toplasm is the designation now almost universally applied
to it. To Max Schultze, writing in 1861, belongs the credit
more than to any other one man, of comprehending the
nature of cells as we now understand them, and the terminol-
ogy in which Oscar Hertwig expresses Schultze's achieve- ■
ment is of prime significance. Although Schultze retained
the name cell, naturalized in anatomy by Schleiden and

156 The Unity of the Organism

Schwann, he "defines it," Hertwig says, "as a bit of proto-
plasm endowed with life, in which lies a nucleus." '"^

Almost simultaneously with this insight by Schultze, Carl
Briicke, contemplating cells from the standpoint of their
complex structure as well as from that of their ensemble of
life activities, advanced to the conception of the cell as an
organism^.

The language in which Briicke expresses himself on this
point is of sufficient interest to warrant quoting: "We
must ascribe to the living cell, in addition to the molecular
structure of the organic compounds which it contains, still
another and a differently constituted structure, and it is
this which we designate as organization.^^ ^^ And in another
connection he introduces the phrase, now firmly established
in biology, elementary organism, as a designation for the
cell.

One of the securest aspects of the cell-theory was reached
only when the conception organism was applied to the cell.
Both historically and logically, the organism is made to do
duty in interj^retvtig tlie cell. Whatever validity the con-
ception cell has in the modern cell-theory, is due in large
measure to whatever validity the conception organism has.
But the conception organism was well established in biology
long before the conception cell was; hence the justification
of the statement that historically the organism interprets
the cell. Organism as an idea is prior and contributary to
cell as an idea. That logically also the cell is partly in-
terpreted by the organism is seen in the fact that observers
agree in ascribing to the cell the most distinctive attributes
of the organism : namely those of metabolism, reproduction,
response to stimuli, etc.

Our birds-eye view of the cell-theory enabled us to see
that if it be held in the broad sense in which it is con-
ceived by many but not by all biologists, it consists of two
parts: — one a firmly established generalization of observed

The Organisvi and Its Cells 157

facts, the other a vaguely stated hypothesis. We further
saw tliat the secure generalization has two quite distinct
parts, the one stating that higher organisms arc made up
of cells, the other stating certain cardinal facts about
the cell itself. But later examination fixed attention on the
fact that the theory as now lield regards the cell itself as an
organism. In other words, the two essential components
of that part of the theory which is solidly grounded interpret
each other : By showing how the organism is made up, the
cells interpret the organism ; and by showing what the cell
is in its fundamental attributes, the organism interprets the
cell. The cell is a "key" to the nature of the organism, but
not so in "last analysis" for, at least in equal measure, is
the organism a "key" to the cell. Or, if the idea of heredity
be introduced into the cell-theory, not more than half the
truth is contained in the statement that the cell "embraces
all hereditary qualities in its substance," for we have seen
that one of the corner-stones of the modern conception of
the cell, as laid down by Schultze and Briicke, is that
the attributes of the organism belong to it also, not indeed
merely hidden "in its substance," but patent and observable.
If we restrict attention to the germ-cells and apply to
them the idea of hereditary qualities embraced in their sub-
stance, we are still bound, as consistent evolutionists, to ask
how the germ-cells came by these qualities. No answer is
forthcoming to this inquiry which does not essentially involve
the fact that the germ-cells received the qualities from the
])arent organisms. The interpretative relation between the
organism and its cells is one of strict reciprocality whether
the germ-cells or soma-cells be regarded, even in the broad
general terms of the cell-theory. The problem of the or-
ganism and its cells is the general form of the old special
problem of the hen and the egg. Which came first, runs the
familiar conundrum, the hen or the egg? Expressed in
scjeptjfic terms, the questiop is, which interprets or explains

158 The Unity of the Organism

the other, tlic parent organism or the germ-cells? If the
cell-theory be taken in the broad sense above considered,
the aspect of it which we are holding to be erroneously
hypothetical, would answer that the germ-cells interpret the
parents. According to our standpoint, on the other hand,
this hypothesis is inadequate in that it tells at least no more
than half the truth. The parents interpret the germ-cells
quite as truly as the germ-cells interpret the parents. They
follow each other in a casually related, regularly alternating
series; and biology has no inductive ground for supposing
that either term came first in any ultimate sense.

Certai/n Inadequacies of the Cell-Theory

Having now seen that, in the general development and
formulation of the cell-theory, it is literally true that the
organism has interpreted the cell as much as the cell has
interpreted the organism, we must see something of how
this works out in detail.

The impossibility of fully explaining an organism in terms
of its constituent cells seems to have been felt earlier and
more poignantly by students of the normal development
of individuals than by any other class of biologists. De
Bary's epigrammatic statement, already quoted, "The plant
forms cells; the cell does not form plants (Die Pflanze bildet
Zellen, nicht die Zelle hildet- Pflanzen)^^ was induced primar-
ily by observations of his own and others on developing
plants. Here it is easily demonstrable that the form of
the growing tip is often assumed before the mass divides
up into cells. In other words, the- formation of cells is
certainly in these cases a secondary even though an essential
phenomenon.^ ^

(a) As Tested by Embryonic Development

On the side of animal development, C\ O. Whitman was
the first to produce arguments, both comprclicnsive and ir-

The Organism and Its Cells 159

refutable, against the doctrine of cell hegemony, though Carl
Rauber, Adam Sedgwick, (). Hertwig and a few others had
already become more or less positive dissenters from the
prevailing view. Whitman's studies on the initial embryonal
stages of bony fishes appears to have strongly impressed
upon him the subordination of the cells to the general needs
of the developing fish. "That the forms assumed by the
embryo in successive stages are not dependent on cell-division,
may be demonstrated in almost any ogg. Watch the ex-
pansion of the blastoderm in the pelagic teleost egg^ the
formation of the germ-ring, and especially the axial con-
centration of material, which is so beautifully illustrated in
these eggs. Such developmental processes are, if I mistake
not, clearly indicative of some sort of organization." ^^ And
approaching the problem from a slightly different angle,
he says : "May we not go further, and say that an organism
is an organism from the egg onward, quite independently
of the number of cells present? In that case, continuity of
organization would be the essential thing, while division into
cell-territories might be a matter of quite secondary im-
portance." ^^

It was the domination of cell division by forces other than
those belonging to the cells taken independently that especi-
ally held his interest. "The more carefully we compare the
cleavage in different eggs, the more clear it becomes that the
test of organization in the egg does not lie in its mode of
cleavage, but in subtile formative processes. The plastic
forces heed no cell-boundaries, but mould the germ-mass re-
gardless of the way it is cut up into cells." ^* And he
clearly saw that to fly from cells to nuclei, there to seek
final explanatory refuge, as Sedgwack particularly had pro-
posed, was no more satisfactory than to stay with the
cells.

"The essence of organization," he says, "can no more
lie in the number of nuclei than in the number of cells. The

160 Tl e Unity of the Organism

structure whicli we see in a cell-mosaic is something super-
added to organization, not itself the foundation of organi-
zation." Then follows this pregnant sentence : "Compara-
tive embryology reminds us at every turn that the organism
doaninates cell formation, using for the same purpose one,
several, or many cells, massing its material and directing
its movements, and shaping its organs, as if cells did not
exist, or as if they existed only in complete subordination to
its will, if I may so speak." ^^ After sketching the rise and
fall of that puzzling structure in many vertebrate embryos
known as Kupfter's vesicle. Whitman writes : "This re-
markable reproduction of a form-phase that is to last only
a few hours and then pass away without leaving a visible
trace of its existence, cannot be explained as due to cell-
formation nor as the result of indiindiuil action or inter-
action on the part of the cells. The embryonic mass acts
rather as a unit^ tending always to assume the form peculiar
to the state of development reached by its essential 'archi-
tectonic elements,' (Briicke), elements that are no less real
because, like the atom and molecule, they are too minute to
be seen by the aid of our present microscopes. That cells
as such do not participate in this formative act, is shown
by the mode of development of the vesicle and by the absence
of cells in its ventral and lateral wall." ^^

We have now examined Whitman's position far enough
for our present point; that, namely, of showing the strength
of his conviction that cells taken individually furnish no
adequate explanation of the normally developing individual
organism. The evidence he presents to this end never has
been nor, I am persuaded, can ever be overpowered. On the
other hand, any one who will study, as Whitman himself
says, "more faithfully the living embryo during its forma-
tion" ^"^ will find abundance of further evidence to the same
effect. So far — and this is a very long way — Whitman was
crystal clear. Further than this he was unable to break away

The Organism and Its Cells 161

from the old elenieiitalist form of reasoning.

Tlie name of E. B. Wilson was coupled with that of Whit-
man in my general introductory remarks on the appearance
in modern biology of the conception of the organism as a
whole. We will now examine in some detail this authority's
views concerning the cell in development. Discussing the so-
called Mosaic theory of development in 1893 Wilson said,
"I will here point out one all-important point which is
definitely established by tlie work of Driesch and other ex-
perimentalists, and which is accepted by all opponents of
the mosaic theory, namely, that the cell cannot be regarded
as an isolated and independent unit. The only unity is that
of the entire organism, and as long as its cells remain in
continuity they are to be regarded not as morphological
individuals, but as specialized centres of action into which
the living body resolves itself, and by means of which the
physiological division of labor is effected." ^^

After referring to Schwann's having drawn "the con-
clusion that the life of the organism is essentially a com-
posite ; that each cell has its independent life ; and that the
whole organism subsists only by means of the reciprocal
action of the single elementary parts," Wilson says : "It is,
however, becoming more and more clearly apparent that this
conception expresses only a part of the truth, and that
Schwann went too far in denying the influence of the or-
ganism upon the local activities of the cells. It would, of
course, be absurd to maintain that the whole can consist
of more than the sum of the parts. Yet, as far as growth
and development are concerned, it has now been clearly
demonstrated that only in a limited sense can the cells be
regarded as co-operating units. They are rather local
centres of a formative power pervading the growing mass
as a whole, and the physiological autonomy of the individual
cell falls into the background. Broadly viewed, therefore,
the life of the multicellular organism is to be conceived as a

162 The Unity of the Organism

whole, and the apparently composite character which it may
exhibit is owing to a secondary distribution of its energies
among local centres of action." ^^

Our only object in this section is to place before the
reader as much as practicable of the views of biologists that
the organism and not the cells of which it is composed is
the main thing in development. It would consequently be
out of place to go into a critical examination of this lan-
guage. It will, however, be permissible by way of intimation
of what will be involved in the discussion, to ask how the view
that "the life of the multicellular organism is to be con-
ceived as a whole," can be made to tally with the view ex-
pressed in the first sentence of The Cell, already quoted,
that "the key to all ultimate biological problems must, in
the last analysis, be sought in the cell." ^

Wilson's authority is deservedly so great in all these
matters that his utterances will be taken as one of the
main centres around which our examination of the cell theory
will hover. On this account, I quote somewhat more at
length than would be essential to show merely his general
position. In the chapter, "Cell-division and Development,"
he writes : "It remains to inquire more critically into the
nature of the correlation between growth and cell-division.
In the growing tissues, the direction of the division-planes
in the individual cells evidently stands in a definite relation
with the axes of growth in the body, as is especially clear
in the case of rapidly elongating structures (apical buds,
teloblasts, and the like), where the division-planes are pre-
dominantly transverse to the axis of elongation. Which of
these is the primary factor, the direction of general growth
or the direction of the division-planes.'^ This question is a
difficult one to answer, for the two phenomena are often too
closely related to be disentangled. As far as the plants are
concerned, however, it has been conclusively shown by Hof-
mcister, De Bary, and Sachs that the growth of the mass

The Organism and Its Cells 163

is the primary f Mctor ; for the characteristic mode of growth
is often shown by the growing mass before it splits up into
cells, and the form of cell-division ada})ts itself to that of
the mass : "Die Pflanze bildet Zellen, nicht die Zelle bildet
Pflanzen.' jNIuch of the recent work in normal and experi-
mental embryology, as well as that on regeneration, indi-
cates tliat the same is true, in princi])le, of animal growth.
. . . Still more recently this view has been almost demon-
strated through some remarkable experiments on regenera-
tion, which show that definitelj^ formed material, in some
cases even the adult tissues, may be d^^'ectly moulded into
new structures." ^^

I go no farther here in the examination of Wilson's biolog-
ical philosophy than to point out that, in spite of his clear
perception, as indicated by these quotations, that the organ-
ism as a whole plays a determining part in the development
of its constituent elements, his latest statements show that he
is succeeding all too well in obeying the ancient injunction:
"Let not thy right hand know what thy left hand doeth."
Presumably his left hand still clings to the "whole mass
as a moulding power of the parts." But his right hand
seems now more confident than ever of finding the "key to
all ultimate biological problems" in the cells, or maybe in
the chromosomes.

In a lecture published in 1913, speaking of the inter-
esting phenomenon of "criss-cross heredity" in the short
and iong-winged flies lately studied by Morgan, where the
sons are like their mothers and the daughters are like their
fathers, Wilson savs: "This case, and many others of similar
type, may be completely explained through our knowledge
of the relation of the chromosomes to sex. . . . All the facts
revealed by experiment are very simply and completely ac-
counted for by the simple assumption that the x-chromosome
is responsible not only for sex, but also for the short-winged
character." ^^ Our critical examination of this whole mat-

164 The Unity of the Organism

ter, when we come to it, will lead us to see that the essence
of Wilson's criticism of Schwann relative to cells, quoted
above, will now have to be applied to himself relative to
chromosomes : "This conception expresses only part of the
truth, and Schwann went too far in denying the influence
of the totality of the organism upon the local activities of
the cells," said Wilson in 1900. Now we shall have to say
that Wilson goes too far in denying, by implication, the
influence of the totality of the organism in determining sex;
for the assumption that the x-chromosome is "responsible
for sex," and that the facts are "simply and completely ac-
counted for" by this assumption surely involves this impli-
cation.

Driesch's views touching the relation of the organism to
its constituent elements generally are very important, and
will have to be considered under several heads. We have
already referred to his proposal to purge the cell- theory of
all that is hypothetical in it. Continuing the previous quota-
tion, we have this : " . . . attempts to conceive the organ-
ism as a mere aggregate of cells have proved to be wrong.
It is the whole that uses the cells, ... or that mav not
use them." ^- His much discussed theory of "equipotential
morphogenic system" had its inception, as is well known, in
his study of the blastomeres in early embryonic development.
At present, I go no further than to point out that while it
seems certain to Driesch that the "organism as a whole"
is essentially implicated in some fashion in producing organic
structure, it also seems certain to him that he knows nothing-
significant about the nature of that implication. He says:
"So all we know about the proper stimuli of restrictions is
far from resting on any valid grounds at all ; let us not
forget that we are here on the uncertain ground of what
may be called the newest and most up-to-date branch of
the physiology of form. No doubt there will be something
discovered some day, and the idea of the 'whole' in organi-

The Organism and Its Cells 1(15

zation will probably play some part in it. But in what man-
ner that will happen we are quite unable to predict." ^^

I conclude this inventory of expressed recognitions by
competent observers that the organism dominates its cells
in embryogenesis, with two modes of formulating this recog-
nition that are specially significant. They are expressions
of the unity or oneness of the individual organism in time;
and of its unity or oneness in space.

E. G. Conklin has expressed the first truth with com-
mendable decisiveness and simplicity: "Furthermore, from
its earliest to its latest stage an individual is one and the
same organism ; the egg of a frog is a frog in an early stage
of development and the characteristics of the adult frog
develo]! out of the egg, but are not transmitted through it
by some 'bearers of heredity.' " ^^ This proposition is so
nearly self-evident that it would not need insisting upon
but for its having been obscured by sophistical discussions
of whether development is "predetermined" or "epigenetic."
Huxley stated it in essence when he declared it to be "certain
that the germ is not merely a body in which life is dormant
or potential, but that it is itself simply a detached portion
of the substance of a pre-existing living body."

Nageli put it in still more concrete temis when he af-
firmed that the hen's egg differs from the frog's egg as
much as the grown-up hen differs from the grown-up frog ;
that the species is no less certainly contained in the egg
than in the adult. However this speculator befogged the
truth with his fanciful idioplasm. The best expression of
tlie spacial unity of the developing organism with which I
am acquainted is that by F. R. Lillie : "The traditional
view, held by many embryologists at the present day, is that
the physiological unity arises in the course of embryonic
development by the secondary adaptation of originally in-
dependent parts to one another. But this explanation has,
in my opinion, become untenable, and nmst be replaced by

166 The Unity of the Organism

tlie view that there are certain properties of the whole, con-
stituting a principle of unity of organization, that are part
of the original inheritance, and tJms continuous through
the cycles of the generations and do not arise anew in
each.'' '"

For the present I do no more than remind the reader that
the itahcs here are Lillie's, not mine ; and that his clear and
empliaticallj expressed conclusion does not rest alone on the
experiments presented in the paper quoted from, but had
been, in essentials, reached by him through earlier studies
on normally developing animals.

Several of the few biologists who have taken a positive
stand against the dogma of the all-sufficiency of the Cell in
biology have deplored the well-nigh universal custom of
early indoctrinating young students with that part of the
cell-theory which I have characterized as vaguely hypothe-
tical. Adam Sedgwick in particular concentrated his fire
on this aspect of the matter. There can be no doubt that
many if not most recent elementary text-books are unwitting
sinners in this. On the outmost threshold of the temple
of biological science, the student is made to feel, by the
priests within, that the head should be bowed, the knee bent
and the voice subdued when certain things, some difficultly
visible, some wholly invisible, things situated deep in the
interiors of the plants and the animals to be studied, are
mentioned. Among these minute objects of adoration, the
Cell holds a commanding place. "Every scientific animal
and plant anatomy must, consequently, take its starting
point in the doctrine of the Cell." ^^* No matter how long
a shelf of elementary text-books on botany and zoology one
examines, he will rarely fail to find something akin to this
explicit statement in R. Hertwig's excellent Lehrhuch der
Zoologie.

According to this the anatomy of Vesalius, Wm. Harvey,
John Hunter and George Cuvier, and others who lived and

The Organism and Its Cells 1G7

wrought before there was any cell-theory, are unscientific.
But not quite all writers of guides for the young see the mat-
ter this way. B. Hatschek may be mentioned as one excep-
tion. In his Lchrbuch he writes: "If therefore we raise the
question why one cell body undergoes this, another that
transformation, we shall indicate as a chief cause the rela-
tion of the cells first of all to their neighbor cells, and then
to the totality of the body." For the moment we will be
satisfied with this recognition that in the relation of the
cells to the totality of the body as well as to one another,
resides a cause of differentiation of the cells in the com-
pleted organism, and will not be querulous over the state-
ment that this relation stands "first of all" as a cause.

I believe enough has now been brought forward on the
pros and cons of the cell-theory of development to establish
two things : Those biologists who by reason of their own
researches, either through unaided observation or through
observation assisted by experiment, are most deserving of
being heard on the subject are persuaded, first, that not-
withstanding the fact that the developing and developed
organism is wholly produced through the multiplication and
differentiation of cells, these cells are not an adequate ex-
planation of embryogeny ; and, second, that the organism
as a totality must enter as an essential element into any
adequate explanation of the phenomenon.

(6) As Tested by Isolated Cells and Tissues

Before Lillie's contention that the traditional explanation
of the developing embryo has "become untenable and must
be replaced by the view that there are certain properties
of the whole, constituting a principle of unity of organiza-
tion, that are part of the original inheritance,^^ can gain
much influence on biological thinking, it will have to be
examined from many directions.

168 The Unity of the Organism

What, on cursory view, looks more like confirmation of
the theory of cells as wholly independent elements whose
cooperation explains the organism, than any facts recently
brought to hght, are some of the results of recent researches
on isolated tissues — "tissue cultures," as they are frequently
called. The German phrase, ueherlehende Gemebe, — sur-
viving tissues — for these is very apt.

Although the work of Alexis Carrel in this realm has at-
tracted much interest and attention even on the part of
the general public, it is recognized by biologists, including
Dr. Carrel, that R. G. Harrison not only initiated the
methods employed, but also reached highly important results
by applying them. The specific purposes and results of
Harrison's researches, and his general attitude to^yard prob-
lems of individual development, are of prime moment for
our discussion. His central aim was to end the perennial
debate over the mode of origin of nerve fibers in vertebrate
embryos, and the persistence, technical skill, and cogency
of reasoning with which he worked at the problem until he
advanced its solution sharply beyond the point reached by
any one else, are admirable.

According to the view attributed to Wilhelm His, the
axis cylinders of the nerve fibers of the central nervous
system are outgrowths of the ganglionic cells, their con-
nection with the end organs being secondary. The other
view, less generally held, originally advanced by the physi-
ologist Victor Hensen, is that the fibers are differentiations
within protoplasmic strands which have connected the cen-
tral and periplieral cells from the very time when the cells
themselves were formed, their character as nerve fibers being
taken on only when, through the activities of the growing
embryo, conducting paths are needed.

Harrison's earlier attempts to terminate the controversy
by transplanting limb-buds, under various conditions, from
one frog tadpole to another, had led him to believe strongly

The Organism and Its Cells 1G9

in the first mentioned view, though the methods of experi-
mentation employed were not such as to make it possible
for him to see the actual outgrowth of the fibers. He there-
fore tried to find a way of keeping sufficiently small isolated
bits of the embryonal neural tube to enable him to observe
the growths under the microscope if they actually occur.

A summary of his results stated in his own words is :
"Pieces of undifferentiated embryonic tissue, when isolated
under aseptic precautions in clotted lymph, will live for
weeks and undergo at least the initial stages of normal his-
tological differentiation : cells from the axial mesoderm
give rise to striated muscle fibers ; epidermal cells form a
cuticular border; typical cliromatophores and a mesenchyme-
like tissue are formed from pieces containing portions of the
neural tube and axial mesoderm ; the walls of the neural
tube and the primordia of the cranial ganglia give rise to
long hyaline filaments closely resembling embryonic nerve
fibers.

"Tissues grown in lymph function characteristically, as
is seen in the movement of cilia and the contraction of muscle
fibers when left in organic continuity with fragments of the
neural tube." . . . "The experiments show that neuroblasts
are competent to form primitive nerve fibers within a foreign
unorganized medium simply by the amoeboid outgrowth of
their protoplasm. By eliminating from the periphery all
formed structures which have heretofore been supposed to
transform themselves into nerve fibers and leaving only
the neuroblasts in the field, it is demonstrated that the lat-
ter are the sole elements essential to the formation of nerves.
The concepts of both Hensen and Held are rendered un-
tenable." -^

Thus a developmental point of capital importance which
had been debated at length and with considerable spirit as
long as investigation was conducted upon the organism in
its entire state, was solved by separating from the rest a few

170 The Unity of the Organism

cells and finding that when thus isolated they, were able to
develop much as they do normally within the organism.
Surely no more conclusive proof that the cells of an organ-
ism have a large measure of independent life could be asked.
Harrison epitomizes this aspect of his results in a very clear-
cut paragraph : "The energy of outgrowth is immanent in
the nerve cell, and the initial direction of outgrowth is
already determined within the cell before the outgrowth
actually begins. The formation of the fiber is therefore an
act of self differentiation within Roux's definition." ^^

Do not such discoveries favor unquestionably the view
that, in Wilson's way of saying it, "the key to all ultimate
biological problems must, in last analysis, be sought in the
cell?" Some authors, as. for example Oppel, answer with a
very positive yes^ but I have found nothing in Harrison's
writings to enable one to be sure what he would do were he
to answer this question by choosing between an unqualified
yes and an unqualified no.

However, discussing the general question of the relative
trustworthiness and value of experimental studies of the
sort devised by him, and those of the sort by which prob-
lems of histogenesis are ordinarily prosecuted, he has ex-
pressed views which bear strongly on the question, and
which we present in his own language:

"Why, then, should we, in morphology, be still so domin-
ated by the conception of the object as it occurs in nature,
the organism as a whole, which to many seems to be a sort
of fetish not to be touched lest it show its displeasure by
leading the offender astray.^ There is no real ground for
maintaining this attitude. On the contrary we should en-
deavor to extend our experimental analysis wherever pos-
sible, recognizing that through stud}^ of the abnormal, which
consists merely of those combinations of conditions and
effects tliat do not ordinarily occur in nature, we have the
means of reaching an understanding of the normal, and that

The Orgnnism and Its Cells 171

it is necessary to investigate the properties of the constit-
uent parts of organisms before we can hope to under-
stand them in their entirety. Because of our limited knowl-
edge, we are for the present setting ourselves an impossible
task if we expect to determine with certainty by means of
a few experiments exactly the combination of factors in-
volved in the normal ontogeny of any particular structure.
In fact we can never 'explain' the processes of normal de-
velopment with more than a certain degree of probability,
until we succeed in synthesizing organisms from simple
known constituents or construct working models that show
all of the essential activities of organisms — achievements
from wliich we still are very far removed. Syntheses may
possibly be made, however, at different stages of the analysis
with components of greater or less complexity. Thus it may
be possible to extend the remarkable experiments of H. V.
Wilson." -'

The manifest worth and practicability of the manipula-
tive methods introduced b}^ Harrison assured their quick
adoption by other workers, and already a considerable litera-
ture has come into being dealing with "surviving tissues."
Owing, it seems, largely to the fact that Dr. Carrel has vig-
orously and skillfully applied the methods in the interest of
surgery, he has attained wider distinction in connection with
the researches than has any one else, tliough several other
biologists and physicians have increased knowledge substan-
tially by the new instrument of discovery.

The remarkable viability of tissues removed from their
native setting in the organism and kept under artificial con-
ditions is well brought out in a recent paper by A. H.
Ebeling. This investigator made cultures of fragments of
the heart of chick embryos seven to eighteen days old, a
few of which lived and flourished nearly a year. "The ex-
periments show," said Ebeling, "that connective tissue can
be kept in a condition of active growth outside of the organ-

172 The Unity of the Organism

ism for more than eleven months, that its mass increases
considerably, and its power of proliferation, after such long
period, is more active than at the beginning of its life in
vitro/' ^^ In one culture, fragments of the heart pulsated
after 104 days. The evidence is now conclusive that various
tissues of numerous animals are able to live and grow and
perform something of their characteristic activities for a
long time after being separated in small fragments from the
organism at various stages of its development.

Another striking attribute proved for the cells of young
embryos is their mobility. Harrison dwells on the cxten-
siveness and significance of this, and all the other investi-
gators are impressed with it. The wandering about and
the putting out of protoplasmic processes by cells of various
sorts, notably by connective tissue and nerve cells, are men-
tioned by all writers. Burrows' account of the behavior
of the growing nerve fibers is particularly full and well
illustrated, and many of the facts are so significant that I
quote at some length from his description : "Growth of
the nerve cells is evident by filaments of various sizes. . . .
The slender filaments are composed of a hyaline homogeneous
protoplasm, while in the coarser bundles the homogeneous
character is altered by the appearance of delicate, longi-
tudinal striations. The latter bundles break up into many
fine filamentous branches. . . . At the end of each of these
growing filaments and branches is the characteristic thick-
ened amoeboid swelling. . . . This is an oval or round swell-
ing of the filament from which protrude many actively mov-
ing delicate pseudopodia. The growth of a fiber consists
in the great prolongation and enlargement of one of these
pseudo])odia with a gradual moving outward of the end
knob along the pseudopod. The growth may be so rapid
that the end knob may entirely disappear, to reappear far-
ther out along the new grown part. . . . During this time
(48 to 72 hours) they may . . . reach a length of from one

The Organism and Its Cells 173

to two niillimetcrs. . . . The activity of such fibers is noted
at the amoeboid end and consists in a constant retraction
and new formation of pseudopodia. All observations on
the movement of the growing fiber suggest an active force
within it causing its extension into the medium." ^^

Describing the activities still farther in connection with
the degeneration of some of the nerves, the author con-
tinues: '^The changes in the nerves are mainly at the end.
Here there is periodic thickening, followed by a slow reduc-
tion in size until the entire nerve has retracted into the
tissue in a manner similar to the retraction of the pseu-
dopodia of an amoeba. These phenomena of extension and
retraction may go on alternately in the same fiber. . . .
The retraction is checked after a time and growth again
proceeds in a different direction for a while when the pro-
cess is again repeated." ^^

This primitive amoeboid activity of the cells is by far
the most common and readily accomplishable. The testi-
mony of all observers is at one on this point. But this
activity is by no means the only kind. Contraction of muscle
fibers was seen by Harrison, as mentioned in the quotation
already given ; a number of other investigators have con-
firmed and extended the observations. Burrows, for instance,
has shown that muscle cells from the embryonic chick heart
may contract rhythmically in cultures. He writes : "The
muscular elements grow much less frequently and cellular
outgrowths from them were observed in only about three
per cent, of the experiments. The outgrowths take place
from the myotomes and the heart, and appear in the form
of short chains of striated cells. The striated cells contract
rhythmically along with the portion of the heart from which
tliey arise." ^^

Holmes has made the suggestive observation that although
completely isolated, partly differentiated muscle cells of a
newt may remain functionally active for eight months.

174 The Unity of the Organism

"they had not changed their form, nor had they under-
gone any marked changes in structure." This result is the
more interesting in that muscle cells of similar sort but
contained in a })iece of larva instead of being isolated, con-
tinued to differentiate.

A number of important questions touching the independ-
ent life of embryonal muscle cells are awaiting; further study,
but enough has been done to leave no doubt that, broadly
speaking, they possess a considerable degree of such inde-
pendence.

Not only are cells able to continue their physical activi-
ties, but in some cases they are also able to go on with
their chemical activities, after being separated from the
organism. The evidence is conclusive, then, that once formed,
a number of kinds of tissue cells may survive for a long
period after removal from the organism and may continue
to perform more or less faithfully their wonted activities.
Can new cells also be produced under the new and unusual
conditions? Undoubtedly. While to a large extent the
changes described by all observers in surviving fragments
are due to the wandering out and wandering about of cells
already in existence, cell multiplication has been clearly
seen by too many good experimenters to leave any doubt
on the main point. The large increase in mass of the frag-
ments described by all those who have 'kept the same cul-
tures alive and active for a long time would be conclusive
even if cell-division itself had not been seen.

Carrel and Burrows were apparently the first to witness
directly cell division. "A culture contains emigrated as well
as proliferated cells. The proliferated elements consist of
connective tissue and epithelial cells, the former predomin-
ating." ^"^ This is explicit though wanting in detail. But
other observers have been sufficiently explicit. As long ago
as 1906, H. Deeljen described with considerable particularity
the division of the polynucleate leucocytes of human blood

The Organism and Its Cells 175

when kept under proper conditions in microscopic prepara-
tions. And more recently Oppel, applying the new methods,
has described, figured, and discussed at length mitotic divi-
sions of cells isolated from various tissues of the cat.

When we pass from the question of the independent life
of individual cells to that of the independence of organs,
or organized groups of cells, the prospect changes consider-
ably. Harrison, in one of his earliest publications, says :
"While the cell aggregates, which make up the different
organs and organ complexes of the embryo do not undergo
normal transformation in form, owing no doubt in part to
the abnormal conditions of mechanical tension . . . the in-
dividual tissue elements do differentiate characteristic-
ally." ^'^ Without raising the question as to how "charac-
teristically" the individual elements can differentiate while
the cell aggregates "do not undergo normal transforma-
tion," the assertion that the aggregates do not transform
into organs is sufficient for the point being made.

Carrel and Burrow^s have described "tubular formations"
in cultures of both the kidney and the thyroid gland of the
chick. The growth of kidney tubules is affirmed with special
particularity. The authors write: "At several points, tubu-
lar formations were observed which extended themselves a
considerable distance toward the middle of the plasma. Their
ends were rounded, their lumina open, and their walls formed
of cells which had the appearance of epithelial cells. These
formations resembled renal tubules." ^^

The production of these structures is surely interesting,
but more interesting is the question raised by the last sen-
tence : are the formations actually renal tubules, or do they
only resemble them? That no organization of cells info
normal organs takes place in these '"'cultures'''' is attested
by all who have pursued these investigations, so the state-
ment by Carrel and Burrows that the formations resemble
kidney tubules is to be taken as literally true, and to be

176 The Uniti/ of the Organism

understood to imply that the resemblance is not sufficiently
close to make them indeed such tubules.

On the matter of organ production by tissues separated
from the body, Burrows has given us a decisive statement.
"Such growing cells," he says, "from an isolated piece of
tissue liave at no time shown evidence of grouping in a form
comparable to organ formation in the body." ^^

Some experimenters appear to have clearly seen the im-
portance of this limitation of power of the tissues, and on
this account have taken rather strong grounds against call-
ing the preparations "cultures." J. Jolly in particular
has his eyes wide open toward the phenomena, though pos-
sibly some details of his criticisms are overwrought. He
says, "In certain tissues m mtro it appears possible for cel-
lular multiplication to continue for some time, that much is
true; but between tliis last effort of certain cells and a
'culture' — a development continued and progressive — there
is a gap, which may be filled up some day. For the present,
it is an abuse of language to attach the name 'cultures' to
the results obtained." ^^ And the author thinks true de-
velopment of kidney tubules is not proved by Carrel and
Burrows.

Denial of development in a strict sense is made also by
A. Dilgcr: "On the basis of this critique and of his own
investigations, the author must emphatically deny that in
the case of cultures of fragments of the mature organs of
warm-blooded animals any genuine growth takes place in
the sense of an organic formation. In this essential the
author would adopt the view of Jolly, that the Carrel-Bur-
rows experiment indeed demonstrates a survival and physio-
logical functioning of tissue fragments, but has nothing to
do with their growth." ^^

It may be un})rofitable to spend time on the question of
what name should be aj^plied to these vmique preparations,
further than to insist that the name settled upon shall not

The Organism and Its Cells 177

give a false impression of their true nature. If they are
to be called "cultures," then tlie word must be understood
to have a somewliat different meaning from what it has
in ordinary biological technology, where the production of
true organisms is always contemplated. Indeed the distinction
is at least partly recognized by Carrel and Burrows, for in
one of their publications they say: "Since the tissues, in
their development, must adapt themselves to the morpholog-
ical plan of the organism, their growth must be constantly
regulated by some iniknown factor. This regulation may be
caused by certain chemical compounds contained in the
blood and the interstitial lymph. . . . Therefore, it may be
assumed tliat the power of growth is kept under constant
restraint, that every organ is compelled to follow the mor-
phological plan of the organism, and normal plasma is far
from being the optimal medium for the culture of normal
cells." 4"^

Now that we are learning so much about the part played
by chemical messengers, or hormones, in normalizing growth
(see Chapter 18, in Part II of this book), the conception
that "every organ is compelled to follow the morphological
plan of the organism" is gaining intelligibility.

This statement goes, by unmistakable inference at least,
to the very heart of the matter. Even were it demonstrated
that embryonal cells and organs are capable of developing
into perfectly normal adult parts when isolated from the
embryos, this would prove that these cells and organs are
capable of independent life in an ontogenic sense only. It
would not prove them so independent in a full sense, that
is, in a phylogenic as well as an ontogenic sense.

The very fact that the adult organs into which they
developed could be pronounced normal would mean that their
development was, in Carrel and Burrows' language, "com-
pelled to follow the morphological plan of the organism."
In other words, the development would be guided by heredity

178

The Unitij of the Organism

just as certainly as though the parts had not been isolated.
And so we are able to see what is implied in Harrison's
remark quoted above, "we can never 'explain' the processes
of normal development with more than a reasonable degree
of probability until we succeed in synthesizing organisms."
If the condition thus placed on explanation of development
is really necessary, such explanation will never be forth-
coming, since to synthesize organisms would be to synthesize
them endowed with their hereditary attributes and powers —
in other words, with their ancestral attributes and powers.
But in order to synthesize them with such attributes and
powers it would be necessary to synthesize not only the
organisms, but also their ancestors — a rather difficult task.

REFERENCE INDEX

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5.

6.

7.

8.

9.
10.
11.
19.
13.
14.
15.
16.
17.
18.
19.
20.

Locy . .
Virchow

249
36

Hertwig, O. ('12) 3

Wilson, E. B. ('00) 3

Wilson, E. B. ('00) 1

Eocy 252

Morgan and Goodrich. , I, 169

Driesch 27

Hertwig, O. ('12) 8

Briicke 386

Wilson, E. B. ('00) 393

Whitman 110

Whitman Ill

Whitman 109

Whitman 119

Whitman 121

Whitman 120

Wilson, E. B. ('93) 8

Wilson, E. B. ('00) 58

Wilson, E. B. ('00) 393

21

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23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.

Wilson, E
Driesch .

Driesch

Conklin ('08)

Lillie, F. R..

Hertwig,

Harrison

Harrison

Harrison

Ebeling

Burrows

Burrows

Burrows

B. ('13)

R. ('95)

('10) ...

('10) ..

('12) ...

('11)

('11)

('10)

Carrel and Burrows ('12)

Harrison ('06)

Carrel and Burrows ('12)
Carrel and Burrows ('12)

Jolly

Dilger

Carrel and Burrows ('11)

821

28
117

90
251

47
841
843
184
273

72

74

2058

416

140

298

78
473
317
562

I

Chapter VII

THE CELL-THKORY NOT SUFFICIENT FOR
EXPLAINING THE ORGANISM

N the preceding chapter the cell- theory was shown to
be inadequate as a complete explanation of the organism
when tested by studies of embryonic development and by
experiments on isolated cells and tissues. We now proceed
to consider other phases of the theory which still further
show its limitations.

More General Iiiadequdcy of the Cell-Tlwory

(rt) As Tested hy the Regeneration and Restitution of

Mutilated Organisms

Few topics of research have a more instructive bearing
on the hypothetical portion of the cell-doctrine than has
that of regeneration, taking the word in its general meaning.
Attention may be called first to the far greater inclination
of investigators to neglect cells as such when studying the
re-development of organisms that have been deprived of
some of their parts than when dealing with their development
from the germ.

Such problems as those of cleavage, of molecular be-
havior, and of cell-lineage, which stand out so conspicuously
in most researches on ordinary embr^^onic development, par-
ticularly those concerning themselves primarily with early
stages, are for the most part conspicuous by their absence
in studies on the rehabilitation of mutilated organisms.

Undoubtedly one reason, perhaps the chief reason, for

179

180 The Unitii of the OrganisTn

this is that regenerative processes so frequently involve con-
siderable masses of more or less differentiated tissues rather
than individual cells. A sort of mass action or mass per-
formance takes place with little or no regard to the indi-
vidualized activities of the constituent clementij, whatever
they may be, cells, nuclei, centrosomes, chromosomes or what
not. The most palpable instances of this mass performance
are afforded by those restorative processes in which cell
division plays no part, or but a subordinate part. These
processes are accomplished by the activity of cells already
in existence, by the re-disposing of old cells, rather than
by the production of new ones. Thus Rand describes how
the "cells of the earthworm epidermis are seen to execute
an extensive movement from their original position to an
adjoining surface not previously occupied by epidermis." ^
This movement, Rand shows, is not a passive one due to
pressure or pull by extraneous forces, but is inherent in tlic
cells themselves, and "must be occasioned by an agency
external to the cell, namely, by some factor of the con-
ditions resulting from the injury." Rand looked carefully
for dividing cells in the region of the wound but could find
no indication whatever of these. To the mode of regenera-
tion, "in which a part is transformed directly into a new
organism, or part of an organism without proliferation at
the cut-surface," Morgan has given the name Trior phallaons,
and sets it over against regeneration accomplished through
proliferation, which he calls epimor pilosis.- All investi-
gators now recognize the importance of this distinction.

While cells occupy only a retired place in much of both
the purely descriptive and the speculative writings on re-
generation, it would be wrong to infer that tlie broader
biological conceptions based on the facts of regeneration
have really ignored the cell-theory to tlie extent that at
first sight seems to be the case. As a matter of fact, it turns
out that in many of the discussions of regeneration which

Cell-Theory not Sufficient for Explaining Organisjn 181

on their face are little concerned about cells, there lies an
abiding faitJi in the cell as the "key to all ultimate biological
problems," those of regeneration with the rest. An illum-
inating instance of this came out some thirty years ago,
before the period in which regeneration was the "firing line"
for elementalist biology. I refer to Vochting's attempt to
explain a great range of phenomena in plants by the polarity
of the plant's cells. This investigator's speculations were
based quite as much on his observations on grafting as on
regeneration, lie having studied this subject along with re-
generation and normal development for the purpose of gain-
ing light on development in general and on still larger
biological questions, rather than for ordinary liorticultural
purposes. In observing the result of grafting pieces of
roots on branches and of branches on roots, of reversing
the ends of grafted pieces, and of manipulating the grafts
in several other ways, he was greatly impressed by the
persistence with which the grafted pieces maintain their
characters. The resemblance in several respects of these
phenomena in organisms to those of the magnet led him
to make the utmost possible of the resemblance.

^Morgan's summary of Vochting's speculation so far as
this concerns the cells may be quoted : "The properties of
the tissue-complex rest, in last analysis, on that of the
cells ; the properties of the whole being only the sum total
of the properties of its elements, so that we may say that
every living cell of the root is polarized, not only longitudi-
nally, but also radially ; each has a different apical and
root pole, a different anterior and posterior pole, and also
right and left polar relations." ^

The conception of polarity in plants and animals, which
has had a conspicuous place in later hypotheses of the pro-
duction and regulation of form, has by no means been re-
stricted to discussions in which cells have occupied the
center of interest ; so this is not the place to present it

18S The Umty of the Organism

in all its aspects. For the setting forth of facts and
opinions drawn from studies on regeneration, to see how
these bear on the cell-doctrine, it is enough to say that
these views of Vochting seem not to have met with much
favor among biologists even as a "working hypothesis."
Morgan has shown conclusively the general objection to
them, and the language in which he expresses himself is
noteworthy : "Exception may be taken, I believe, to parts
of Vochting's conclusions, especially in the light of the re-
cent experiments in grafting in animals. It is by no means
to be granted without further demonstration that the proper-
ties of the whole organism are only the sum-total of the
action of the individual cells. If, as seems to be the case,
the cells are organically united into a whole, the properties
of this whole may be very different from the sum of the
properties of the individual cells, just as the properties of
sugar are entirel^^ different from the sum of the properties
of carbon, hydrogen and oxygen." ^

(/;) As Tested hij the Principle of Aggregation

By the "principle of aggregation" I mean the principle
according to which, though a real unity of the organism
is recognized, that unity is held to be secondary and not
primary. This princi})le would be, as touching the cellular
constitution of the organism, diametrically opposed to such
a principle as that formulated by Lillie and quoted in the
previous chapter, namely that there are properties of the
organism which are "part of tlie original inheritance, and
thus continuous through the cycles of the generations and
do not arise anew in each."

Ap})eal to this principle in behalf of the cell-doctrine seems
to go back to Schwann, but to have received its earliest full
expression by Virchow and Haeckel in the "cell state"
conception. More recently the discovery of that close co-
partnership between organisms of different species known as

Cell-Theory not Sufficient for Kxplaining Organism 183

symbiosis has seemed to some biologists to furnish a type of
secondary association which is both sufficiently unitary and
sufficiently separatist, as regards the ultimate elements, to be
available for the explanation of all biotic organization.

The influence of this aggregative conception of the organ-
ism cannot be said to have been very great, so our examina-
tion of it need not be extensive. We will here consider
only the most plausible form of it, that namely which in-
vokes the principle of symbiosis. S. J. Holmes has worked
out a theory of this type more fully than any one else, so
far as I know ; so his paper, entitled The Problem of Form
Regulation, will serve as the basis of our remarks.

After speaking of the organism as a self-regulating
mechanism in which the whole is kept in functional equilib-
rium by the parts being "held in check" in some way, he
writes : "If we suppose that the various cells constituting
the body have each a different kind of metabolism, and that
the products of each cell are in some way utilized by the
neighboring cells, so that each derives an advantage from
the particular association in which it occurs, we may un-
derstand, in a measure, how this check may be brought
about. This supposed relation is realized in a simple scale
by the cases of s>^mbiosis that occur between plants and
animals and between the algae and fungi of lichens. . . .
There is reason to believe that the same fundamental prin-
ciple which serves to explain the regulation of a simple
symbiotic community of animal and plant cells will apply
to highly developed organisms as well. We may regard the
body of a highly complex organism as a sort of symbiotic
community." '^

Although Holmes nowhere says explicitly that cells are
regarded as the vital units of his hypothetical organism,
yet most of his discussion clearly implies this. Thus, he
first considers the simple case of an organism consisting of
"two kinds of cells" ; then afterwards of one made of a

184 The Unity of the Organism

"number of differentiated cells." From this the vital units
assumed seem undoubtedly to be cells. It is significant,
though, that at times in referring to the "balance," and
"equilibrium," and "interdependence" so manifest in all liv-
ing beings, he speaks of "parts," "elements" and so forth ;
that is, things which might be something other than cells :
"By virtue of this dependence it is, to speak figuratively, to
the interest of each part to play its normal role in the
corporate life." And again, "The supposition that every
higher organism is a s^^mbiotic community on a vast scale
composed of innumerable different elements." ^

Indeed, taking the whole discussion together, it seems as
though the teinn cell as sometimes used does not have the
specific meaning attached to it in modern histology and
cytolog}", but stands in a general way for anything, real
or imaginary, within the organism to which some measure
of independent life is ascribed. Thus, pointing out wherein
his theory differs from Roux's Struggle for Existence
among the Parts of an organism, he says : "The whole
process of development . . . may occur, according to our
theory, without the elimination of vital units of any kind,
whether they be biophors, determinants, or individualities
of a higher order, such as cells or organs. We have con-
ceived the parts of an organism to be engaged in a struggle
for existence, but, as the parts are mutually dependent, the
struggle leads to an adjustment to a norm instead of the
elimination of some parts and the survival of others." ^

What are the "parts" here.'^ Are they biophors, and so
forth? Are some of them individualities of a higher order,
as organs? Are all of them "vital units?" What relation
do they hold to the "cells" talked about and diagrammati-
cally figured, as constituting the hypothetical organism?
Exactly how Holmes would answer these queries can not
be made out from his discussion, yet from our standpoint
they are fundamental questions. But it must be remarked

Cell-Theory not Sufficient -for Explaining Organism 185

that if Holmes uses "cells" in the ordinary sense, his specula-
tion is distinctly a backward step from the conceptions
presented by Roux in his Struggle of the Parts, who, so
far as the constitution of the organism is concerned, frankly
recognizes several orders of parts, and concerns himself very
little or not at all with vital units. For instance, he dis-
cusses the struggle of the Molecules, of the Cells, of the
Tissues, and of the Organs.

It seems worth while to call attention to this because
while professedly adopting Roux's conceptions to a con-
siderable extent. Holmes believes he has improved upon his
forerunner in staking less than the latter does on the
eliminative aspect of the struggle theory. In this I agree
with Holmes, but must at the same time maintain, as above
indicated, that in attempting to conceive the struggle in
the terms of cells, regarding these as vital units in an ulti-
mate sense, he falls considerably behind Roux in speculative
soundness and very far behind him in *the methodological
usefulness of his speculation.

The objection to the aggregative conception of the organ-
ism, no matter under what form it presents itself, is so
conclusive that little time need be taken in presenting it:
There is not an atom of etidence that is really in its favor.
Even the facts which at first sight seem most favorable
to it, namely those of symbiosis on which Holmes chiefly
relies, are found when considered a little more closely, to
oppose it. No symbiotic combination known, even that be-
tween the alga and the fungus to make the lichen, ever
occurs as one organism in the sense that any true organism
is one. The symbiotic, or partnership organism, if organism
it can justly be called at all, never begins its individual life
as a single reproductive cell, either as a spore or as a zygote,
i. e., a fertilized ovum, but each species has to reproduce
itself, just as though the association did not occur. As a
matter of fact, in nearl}'^ all known cases of symbiosis one

186 The Unifij of the Organism

of the members to the partnership actually enters the other
and lives upon it at some stage of the game, so the "living
together*' is really a sort of parasitism. The taxonomic
identitj^ of the "consortia," as the partners are sometimes
called, is lost. Concerning the most famous symbiosis known,
that of the lichens, a class of plants which owes its very
existence as a botanical group to the intimate association
that has been contracted between plants of two other such
groups, fungi and algae, we read, "Strictly speaking, both
fungi and algae should be classified in their respective orders ;
but the lichens exhibit among themselves such an agreement
in their structure and mode of life, and have been so
evolved as consortia, that it is more convenient to treat
them as a separate class. . . . From the s3^mbiosis entered
into by a lichen fungus with an alga, a dual organism re-
sults with a distinctive thallus, of which the form (influenced
by the mode of nutrition of the independently assimilating
alga) differs greatly from that of other non-s3nTibiotic
Eumycetes." ^

As a purely imaginary construction one might, perhaps,
picture an organism produced in this fashion which would
not be "dual," as these authors express it, but monal, that
is, (in organism in the usual zoological and botanical sense.
But since such an organism would be a work of the imagina-
tion, pure and simple, with all observational evidence weigh-
ing against its real existence, this particular form of the ag-
grcgational conception of the organism can not be held to
have any scientific value, especially" if the aggregants or con-
sortia be imagined to be cells.

(c) As tested by the Specificity and Metaplasy of

Differentiated Cells

The question now before us is, how far are cells which are
wholly or largely differentiated into tissues bound, willy nilly,
to continue to be just those tissues, and to produce as they

Cell-Theory not Sufficient for Explaining Organism 187

proliferate, other tissues of exactly the same kind. Nothing
concerning the minute structure of organic heings is better
established than that in general tissue cells are "true to
kind" ; that is, once a muscle or nerve or gland cell, always a
muscle or nerve or gland cell, not only in the particular cell's
own existence but in its progeny also. Clearly this must be
so. Were it not, the organism would really not be an organ-
ism at all; it would be a riot of cells differentiated and un-
differentiated.

So obviously and widely true is this that some biologists
have believed it deserves crystallization into a phrase com-
parable to omne viimm ex livo. Accordingly we have Vir-
chow's omjiis cellula e ccllula transformed by L. Bard into
omnis cellula e cellttZa ejusdem natural. But were this for-
mulation rigidly true, and were the tissue elements absolutely
unmodifiable in their individual lives, the aduTt organism, at
least, would certainly be held in the grip, figuratively speak-
ing, of its cells, and the fact might be taken as evidence of the
weightiest kind in support of the theory that the cells are the
key to all organic phenomena.

^luch truth as there unquestionably is in this aphoristic
statement, researches of later years have produced conclusive
proof that it can stand only after receiving important modi-
fication.

Looking at the problem of the deviation of the cells of an
organism from type in a broad way, though without presum-
ing: to make the classification and discussion exhaustive, we
find that three rather well defined classes of such deviations
have been observed. There are (1) cases in which tissues are
induced to undergo radical and more or less permanent
transformation by coming into close and long-continued
contact wuth new or differently applied influences of the
external world; (2) cases in which the replacement of lost
parts of an organism is effected through either the direct
transformation of tissue of one sort belonging to an intact

188 The Umty of the Organism

part of the organism into other tissues of the newly added
parts, or through the derivation of tissues of the renewed
parts from tissues of another sort in tlie old parts by the
latter's first returning to something like an embryonic con-
dition; (3) cases of transformation of tissues in certain
pathological growths.

Under the first head one of the oldest and most frequently
cited examples is that of the transformation of the soft
mucosa cells lining the vagina into pavement-like cells, when
inversion of that organ occurs. A particularly clear and
interesting example of cell transformation which may be
properly ranged in the same class has recently been reported
b}' Harms. This investigator transplanted pieces of the
thumb pad of the sexually active male frog {Rana fusca)
from one individual to another individual. After about two
months he found that complete union of the grafted piece
had been effected, and that the epithelial cells of the graft
were in a normal condition. The glands, however, peculiar
to the epidermis of these pads showed signs of retrogres-
sive change. In the course of another month or so the
glands had undergone complete transformation into a solid,
wellnigh structureless mass, and the cells of the epithelium
immediately surrounding them had reformed and rearranged
themselves into well-defined encapsulating layers, constitut-
ing what Harms designates as a "metaplastically stratified
epitlielium." This case appears to be, as the author re-
marks, one which "shows all phases of tissue transformation
in a way not open to objection." Tliis case is considerably
different from those previously cited in that the influences
operative in bringing about the tissue changes are more in-
timately connected with the cliemico-vital processes of the
organism, and are less purely mechanical than in the other
cases. Harms does not neglect this aspect of the matter,
but a consideration of it would be out of place here.

Under the second head, one of the most striking and at

Cell-Theory jiot Sufficient for Explaining Organism 189

tlie same time best authenticated instances of transfonination
of tissues accompanying the rej)laccment of lost parts has
been described by Nusbaum and Oxncr. The results of tlieir
researches significant for our present needs are sunmiarily
stated in the translation which follows: ""From what has
been said above, we see that in the regeneration of the an-
terior part of Linens lacteus, which has been robbed of the
entire old alimentary canal, the formation of new tissues
takes place heterogenetically in the highest measure ; tha^^
is, it proceeds in such a w-ay that the new tissues arise from
an entirely strange old tissue from which they arc never
produced under normal conditions. We saw, that is to say,
that the epithelium of the entire new alimentary tract, a
tissue endodermal j)ar excellence, is formed in regeneration
by wander-cells which arise from tlie parenchyma and con-
nective tissue, therefore from a material originally wholly
mesodermal." ^ The elaborate description and illustration
with which they present their observations leaves little to be
desired for making the case trustworthy, even had it not
been confirmed by other workers. Fortunately, however, C.
Dawydoff, a Russian zoologist, working on the same species
at the same time but wholly independently, reached results
identical in every essential particular.

Dawydoff's categorical statement touching the main point
is as follows : "The newly-arisen alimentary canal of Lin^us
lacteus is formed from mesoderm. It is differentiated from
the parenchyma and the walls of the lateral vessels." ^ A
very brief description of the experiment perfonned by these
investigators will suffice to make the crucial part of the
results clear. The nemertean has a long section of body
in front of the mouth, consequently into which no part of
the intestinal canal extends. From this it follows that if
the animal be cut in tw^o anterior to the mouth, the front
piece will be wholly devoid of digestive organs. Notwithstand-
ing this it was found that these gutless, mouthless pieces

190 The Unity of the Organism

would not only continue to live, but would develop into com-
plete worms, the new alimentary tract being formed, as the
quotations show, from the internal tissues of the severed
piece ; that is, from tissues which in the normal worm have
nothing to do with the digestive organs.

The demonstration of this ability of organisms to press
into service certain of their parts to replace other parts
that have been lost, even though the parts implicated are
normally quite different, structurally, functionally and de-
velopmentally, is undoubtedly one of the most important re-
sults of the researches on animal regeneration that were so
eagerly pursued a few years ago. A goodl}^ number of in-
stances of this in widely separated sections of the animal
kingdom have been established beyond cavil.

Nusbaum has performed the useful office of summarizing
these on the basis of the kinds of tissues involved, as fol-
lows:

"1. Formation of muscle elements from epithelial tissues
of ectodermal orioin.

"'2. Formation of connective tissue elements from epi-
thelial tissue of ectodermal origin.

'"3. Formation of muscle elements from differentiated
parenchyma cells of mesodermal origin (from connective
tissue).

"■i. Formation of nerve elements from differentiated epi-
thelial tissues of mesodermal origin." ^^

Suitunari/ of Examination of Inadequacy of Cell-Theory

We have now passed under review several large and quite
distinct groups of knowledge pertaining to those biotic ob-
jects called cells, all of this knowledge favoring the inter-
pretation of these bodies as differentiated parts or members
of the larg-er bodies to which thcv bcloufr. Thev come into
existence one after another as a consequence of the growth

Cell-Theory not Siijjicicnt for ExplainiiKj Organism 191

and differentiation of tJie (organism, and In sti-ict sul)ordina-
tion to its needs. In a word, we are led to see tliat cells
must be regarded as organs of tlie organism just as muscles
and glands and liearts and eyes and feet are so regarded.
They undoubtedly constitute a class of organs rather sharp-
ly set off" from all other classes, but this should not be
permitted to obscure the equally important fact of their
always presenting those attributes which are most general
to all organs, namely those of origination by the growth
and differentiation of the organism, and of being function-
ally subservient to the organism.

Nor should we, while taking note of the attributes of
cells which range them under the general category organs,
neglect to note also the attributes which make them a class
by themselves within that category, namely their similarity
in foiTn, constitution and size, for the whole organic world,
and of still more importance, their office as the implements
or tools by w^hich tlie organism performs the physical
changes and chemical transformations of the materials it
uses.

Advance Toward the Organismal Standpoint Through Con-
ception of the Cell Reached hy Biochemistry Pursued
in Accordance with the Principles of
Physical Chemistry

This last statement turns us back to the concluding sen-
tences of the chapter on The Organism and Its Chemistry.

Our explorations in that field discovered, it will be re-
called, that biochemistry, prosecuted in accordance with the
principles of ph^^sical chemistry, is being led to conceive
the cell as a "highly diff'erentiated system," or an "organ-
ized laboratory" consisting largely of "colloidal complexes"
which constitute, "as it were, a special aj^paratus for per-
forming dynamic chemical events."

192 The Unity of the Organism

Into the details of the physico-chemical conception of the
cell we do not enter again here. Miserably inadequate as
our presentation of the subject was in the previous chapter,
it must suffice for this discussion.

By way of making the conception still more concrete
and vivid, and of emphasizing its importance from the or-
ganismal standpoint I quote Hopkins a little further: "On
ultimate analysis we can scarcely speak at all of living mat-
ter in the cell ; at any rate, we cannot, Avithout gross mis-
use of terms, speak of the cell life as being associated with
any one particular type of molecule. Its life is the ex-
pression of a particular dynamic equilibrium which obtains
in a pol>'phasic system. Certain of the phases may be sep-
arated, mechanically or otherwise, as when we squeeze out
the cell juices, and find that chemical processes still go on
in them ; but 'life,' as we instinctively define it, is a property
of the cell as a whole, because it depends upon the organi-
sation of processes, upon the equilibrium displayed by the
totality of the coexisting phases." ^^

Let us now bring closely alongside these and the pre-
viously quoted statements about the nature of the cell as
seen b}' physical chemistry, statements about its nature as
seen by natural history, these latter statements having been
examined in the preceding chapter. Take this from E. B.
Wilson, for example : "The real unity is that of the entire
organism and as long as its cells remain in continuity they
are to be regarded not as morphological individuals, but
as specialized centers of action into which the living body
resolves itself and by means of which tlie physiological
division of labor is effected."

And this from Whitman : "Comparative embryology re-
minds us at every turn that the organism dominates cell
formation, using for the same purpose one, several, or many
cells, massing its material and directing its movements, and
shaping its organs, as if the cells did not exist, or as if they

Cell-Theory not Sufficient for Explaining Organism 193

existed only in complete subordination to its will, if one
may so speak."

And this from Lillie : "The traditional view, held by many
embryologists at the present day, is that the physiological
unity arises in the course of embryonic development of the
secondary adaptation of originally independent parts to
one another. But this explanation has, in my opinion, be-
come untenable, and must be replaced by the view that
there are certain properties of the w^hole, constituting a
principle of unity of organization, that are part of the
original inheritance, and thus continuous through the cycles
of the generations and do not arise anew in each."

And finally this statement by Conklin of the often ex-
pressed perception that the germ-cell and the adult organ-
ism which develops from it are one and the same individual:
"Furthermore, from its earliest to its latest stage an indi-
vidual is one and the same organism ; the ^gg of a frog is a
frog in an early stage of development."

Recognizing in these four statements a sort of concen-
trated solution of the evidence of our whole discussion of
the cell-theory, that the cells of multicellular organisms are
really organs of the organisms ; that they are not inde-
pendent, ultimate life units but on the contrary exist be-
cause of and in subordination to the organism, how escape
seeing that in such general physico-chemical presentations
of the nature of living substance as those quoted from Hop-
kins whenever the term cell occurs the term organism really
ought to be used? The compulsion to such substitution is
especially direct and compelling from the perception, as
expressed by Conklin, that a frog, for instance, is one and
the same organism whether in the one-celled stage, that is,
existing as a cell, or in the many-celled stage.

But bringing the language of natural history into juxta-
position with that of biochemistry, as we are here doing,
accomplishes more than merely to reveal the necessity for

194 The Unity of the Organism

»

substituting organism for cell in the statements of biochem-
istry. It reveals important details of the general truth that
the organism and not the cell is what physical chemistry is
in reality carrying biochemistry toward. For instance, com-
pare Hopkins' assertion that it is impossible to attribute
cell life to "any one particular type of molecule" with Lil-
lie's that the traditional view according to which cells are
"originally independent parts" and only secondarily be-
come incorporated into the "physiological unity," must be
replaced by the conception that there are "certain proper-
ties of the whole" which constitute a "principle of unity"
that are part of the "original inheritance" of the organism.
The parity here suggested between the natural historian's
objection to conceiving "life" as a phenomenon of "the
Cell," as though on ultimate analysis there were only one
kind of cell, and the modern biochemist's objection to con-
ceiving "life" as a phenomenon of "one particular type of
molecule" should be examined a bit closer. What Hopkins
has in mind in taking a stand against "a particular type of
molecule" as the explanation of life is the "ultimate physio-
logical unit" theory which has cropped up under so many
nomenclatorial garbs in later years, but has reached its
most plausible form, perhaps, in the biogen conception, ably
defended by Verworn.

To this conception, no matter what guise it assumes,
physical chemistry brings the insurmountable objection, so
far as the living cell is concerned, that "life" in the very
simplest expression of it known to observational science, is
yet a great complex of structures and activities which con-
stitute a system. It is a space-occupying, shape-presenting,
self-equilibrating complex. Its very existence is a phenom-
enon of multiplex dynamic unity, the parts of which though
constituting the whole are yet subordinate to the whole.
Hence the modern biochemist's assertion that we cannot
properly speak of the living molecules in the cell> but must

Cell-Theory not Sufficient for Explaining Orqanism 195

tliink of the life of the cell as a property of the cell as a
whole. And hence, too, the natural historian's perception
that he must, in turn, and by the very same general
principles wjiich ouide the physical chemist, insist that life
is a property of the orf^anism as a whole. In Whitman's
expressive language, the "organism dominates cell forma-
tion," exactly as, by imi)lication, Hopkins' language jus-
tifies us in asserting that the cell dominates the "molecules"
of the living substances of which it is constituted.

Likewise the "morphological \)\di\\ of the organism" men-
tioned by Carrel and Burrows as something to which the
tissues "must adapt themselves in their development" (see
quotation in section on tissue cultures) is really the counter-
part in natural history language of the cell as an "organized
laboratory" in biochemical language. And the "unknown
factor" which Carrel and Burrows assume must be added
to the "morphological plan of the organism" to explain the
compulsory adaptation of the differentiating tissues, is sup-
plied by physical chemistry so far as the cell is concerned,
in the dynamical, the self-equilibrating system of phases
recognized as constituting the cell.

But when the perception is reached, as it is through our
examination, that in reality the term "organism" should
take the place of "cell" in biochemical language, the organ-
ism no longer appears as a morphological entity merely, but
as a dynamical, a physiological entity as well, and the "un-
known factor" is sup])lied in the organism-as-a-whole. Once
such a conception of life becomes as clear as it is inevitable,
a seemingly overwhelming difficulty looms up in the fact
that "the organism" as natural history is compelled to deal
with it is infinite in number, theoretically if not practically.
For nothing is more patent than that individual organisms
are the primary material of natural history, and no gen-
eralization of natural history is better grounded than that
no two individuals are quite alike. From which it results

196 The Unity of the Organism

that no individual can be fully understood, fully interpreted,
without itself being made a subject of investigation. No
generalization about organism ])ropcr can be counted on
to apply fully to all organisms ! It is probable that an
ill-defined sense of this difficulty (that of the unreachable-
ness of the whole of living nature by any recognized uni-
versal principle or law) accounts for the turning back of so
many able biologists after they have gone far on the natural
history road. For example, E. B. Wilson's failure to accept
the consequences of his own conclusion, "the real unity is
that of the entire organism," is very likely explicable in
this way. To one who has been so indoctrinated with the
metaphysics which grows naturally out of modern mathe-
matical physics as to make him accept the pronoun'cement
that there are "only two real things in the universe. Matter
and Force," a course of discovery and reasoning which
makes every individual organism, no matter how small and
insignificant, a "real thing" seems preposterous even though
true. But the fact that the conception as modern biology
reaches it is largely due to physics itself through its influ-
ence upon chemistry and biochemistry, ought to contribute
much to the reconciliation of science generally to the con-
ception.

The full meaning of such an exaltation — for exaltation
it undoubtedly amounts to — of the individual can be com-
passed only by a painstaking examination of very many
biological facts and hypotheses and dogmas, this examina-
tion ranging over the whole vast realm of living nature.
Indeed, the final and most convincing evidence for the essen-
tial truth of the conception will be reached only when man
himself and the highest provinces of his nature have been
brought into the examination. By the mode of treatment
adopted in this work we shall not have sounded the deepest
depth explored in it until the end of the last chapters shall

Cell-Theory not Sufficient for Explaining Organism 197

have been reached, those on The Psychic Integration of the
-Organism.

REFERENCE INDEX

1. Rand 48 7. Strasburger et al 417

2. Morgan, T. H. ('01) 23 8. Nusbaiirn and Oxner ... 303

3. Morgan, T. H. ('01 ) . . . . 177 9. Dawydoff 6

4. Holmes, S. J 278 10. Niisbaiim 16

5. Holmes, S. J 279 11. Hopkins 220

6. Holmes, S. J 304

Chapter VIII
FURTHER EXAMINATION OF THE CELL-THEORY

OO pervasive have been the efforts to interpret organic
^^development in accordance with the cell-theory that to
examine them exhaustively is impossible. All one can do
is to choose some of the most prominent and assume that
if the criticism succeeds with these major efforts it could
succeed with the minor ones.

The Mosaic Theory

Two diametrically opposed interpretations of the early
developmental states of the organism have figured largely
in later biological theorizing. According to the first, the
constituent cells of the earliest cleavage stages hold the re-
lation to one another of the stones in a mosaic work ; ac-
cording to the second, each cell is "totipotent," that is, sup-
posedly capable of producing the entire organism.

What the Mosaic Theory Is

What the phrase "mosaic work" means when applied to
an embiryo may be stated in the words of Roux himself, the
discoverer of the phenomena on which the conception rests.

"Mosaic work" designates those "developmental phenom-
ena through which in many eggs, those of the frog for in-
stance, eacli of the two or four first cleavage cells (or the
complex of descendants of these) develop hy thevuehyes
alone into the corresponding body j^art, for example into

198

Further Examination of the Cell-Theory 199

half embryos and so forth, consequently without the forma-
tive cooperation of other parts, so are fashioned independ-
ently, like the stones of a mosaic picture. This takes place
through the 'self-differentiation' of separate cleavage cells
or later separate organ-foundation or in fact artificially de-
limited parts, and is possible only in 'typical' development
since 'atypical' development must proceed with far reaching
formative regulation." ^ And along with this definition of
mosaic work the definition of the mosaic theory should be
noticed. "The mosaic theory is the theory which explains
or at least makes intelligible the 'mosaic work.' It rests
upon the assumption of different qualities in the separate
cells (cell body or also cell nucleus) or organ-foundations
etc. capable of 'self-differentiation'."

Obviously, were it generally true that the cells of an or-
ganism are as distinct as the individual stones in a mosaic,
not only as to their form and structure, but also as to their
activities, including their powers of differentiation, this fact
would go far toward a demonstration that cells really are
the "key to all ultimate biological problems" and the central
thesis of biological elementalism, namely, that the final ex-
planation of all organic phenomena lies in the elements con-
stituting organic bodies, would have found an almost im-
pregnable stronghold. On this account the mosaic theory
has been far more eagerly defended and combatted than its
merits as a strict scientific hypothesis warrant. For this
reason too, it will be profitable for us to devote somewhat
more attention to it than we could otherwise afford.

The central facts on which the mosaic theory rests are
familiar to all students of embryology. Roux killed one of
the two cells of frog eggs when they were in the two-cell
stage of development, by pricking it with a heated needle.
In some cases the other cell remaining uninjured developed
into a half-embryo of somewhat such character as one would
get were he to split a nonnally developed embryo lengthwise

SOO The Unity of the Organism

in the dorso-ventral plane of the body. He then killed three
of the four cells of embryos in the four-celled stage, and in
a few instances got something from the remaining cell quite
like a quarter embryo. On these observations Roux based
the somewhat bold hypothesis that "the development of the
frog's gastrula and of the embryo immediately following the
gastrula-stage is, after the second cleavage-period, a mosaic
work of at least four vertical self-developing (or differen-
tiating) parts." To this, however, was added the shelter-
ing statement, "how far this mosaic work is changed by a
change in position of material in the later development, can-
not be determined."

So striking a series of experiments and so far-reaching
an hypothesis were naturally not permitted to stand long
without re-examination. O. Hertwig was the first to try the
experiment again. His results were quite different from
Roux's. He got no hemi-embryos at all, but on the contrary
a number of whole embryos, more or less badly deformed in
various ways. It should be borne in mind that Roux's
method of killing the cells did not remove the injured cells.
These remained in full or slightly diminished mass, but
wholly inert, as originally supposed, when the operation was
entirely successful. Hertwig, on the contrary, believed that
usually the life of the pierced cells was not entirely de-
stroyed, but that whether quite dead or not, they exerted
an important influence on the developing part, and he
hazarded the opinion that could one of the two cells be
entirely removed, the other would produce a complete em-
bryo though of reduced size.

After much discussion between Roux and Hertwig and
others who came into the field, it was shown by Morgan that
"when the black pole of the uninjured blastomere remained
up, the blastomere developed in all cases observed into a
half -embryo. Conversely, those eggs in which the white pole
was turned upward, formed, in most cases, whole embryos

Further Examination of the Cell-Theory 201

of half-size.^^ It thus seems that the mosaic hypothesis for
the frog is partly true. Under some circumstances tlie
cells seem more or less like the stones in a mosaic, under
other circumstances however they do not. Later work, par-
ticularly by Roux, Curt Ziegler, Morgan and Ellen Torelle,
has in general confirmed this much modified form of the
hypothesis in the case of the frog. It has at the same time
shown how much more complicated the whole matter is than
Roux's original simple statement would lead one to suppose.
But the frog is not the only animal in which the cells of
the early embryo present something of the mosaic character.
C. Chun discovered that one of the cells of the two-celled
stage of a Ctenophore would develop as a half-embryo if
isolated from its mate. Driesch and Morgan confirmed this
discovery in general, but pointed out certain details of
structure of the resulting organisms which make the latter
depart quite fundamentally from half-organisms in a strict
sense. For instance, a true ectoderm covered over the side
that would be the cut surface were two half-animals to be
produced by halving a whole one with a knife. Further,
some of the internal organs, notably the endodermal pockets,
were not merely what they would be in a half-animal, but
were as much like those of a whole animal. The normal
animal has four, so a typical half-animal would have two,
but the half-animals produced from isolated blastomeres
had three. Several later investigations on ctenophore eggs
have been carried out, the upshot of all being that with
very decided reservations the cells of the young embryos
of these animals may be looked upon as the "stones in a
mosaic work." A few other kinds of animals, for example
the mollusc llyanassa ohsoleta show something of the same
sort of developmental capacity.'*^

SOS The Unity of the Organism.

A Modicum of Truth in the Mosaic Theory

It is, then, fully established that in some animals the
cells of the early embryos are so specified or individualized
that each develops to a considerable extent in its own way,
that is, more or less independently of its neighbor cells,
and hence may be crudely compared to the stones in a
mosaic work — crudely, we must insist, since stones as mem-
bers of a mosaic work do not develop at all.

The Theory of Totipotence

This theory is the other side of the shield, the side which
looks as though the cells of the early embryo are "totipo-
tent," that is, as though each cell were able to produce the
whole organism instead of only a pre-ordained portion of it.
Chieftainship, both experimental and speculative, in this
theory of developing embryos is universally accorded to
Hans Driesch. The discoveries by him which had such per-
vasive influence on biological thinking for more than two
decades were first published in 1891. His recent popular
account of his work in The Science and Philosophy of the
Organism, will best serve our present need.

Experimental Facts on Which the Theory Rests

Three years after the publication of Roux's experiments
on the frog's egg, above referred to, Driesch tried essen-
tially the same experiment, but on a different animal and
by a different method. He writes : "It was known from
the cytological researches of the brothers Hertwig and
Boveri that the eggs of the common sea-urchin Echinus
microtuherculatus are able to stand well all sorts of rough
treatment, and that, in particular, when broken into pieces
by shaking, their fragments will survive and continue to

Further Examination of the Cell-Theory S03

segment. ... I shook the germs rather violently during
the two-cell stage, and in several instances I succeeded in
killing one of the blastomercs, while the other one was not
damaged, or in separating the two blastomeres from one
another.

"Let us now follow tlie development of the isolated sur-
viving cell. It went through cleavage just as it would have
done in contact with its sister-cell, and there occurred cleav-
age stages which were just half of the normal ones The
stage, for instance, which corresponded to the normal six-
teen-cell stage . . . showed two micromeres, two macromeres
and four cells of medium size, exactly as if a normal sixteen-
cell stage had been cut in two ; and the form of the whole was
tliat of a hemisj^here. So far there was no divergence from
Roux's results. . . .

"I now noticed on the evening of the first day of the ex-
periment, when the half-germ was composed of about two
hundred elements, that the margin of the hemispherical germ
bent together a little, as if it were about to form a whole
sphere of smaller size, and, indeed the next morning a whole
diminutive blastula was swimming about. I was so much
convinced that I should get Roux's morpliological result in
all its features that, even in spite of this whole blastula, I
now expected that the next morning would reveal to me the
half-organisation of my subject once more. . . . But things
turned out as they were bound to do and not as I had
expected ; there was a typically whole gastrula on my dish
the next morning, differing only by its small size from a
normal one; and this small hut xehole gastrula was followed
by a whole and typical small pluteus-larva.

"That was just the opposite of Roux's result; one of the
first two blastomeres had undergone a half-cleavage as in
liis case, but then it had become a whole organism by a sim-
ple process of rearrangement of its material, without any-
thing that resembled regeneration, in the sense of a comple-

S04 The Unity of the Organism

tion by budding from a wound." ^

Driesch went on with his sea-urchin eggs, as Roux had
with the frog-eggs, to see what cells would do if separated
in the four-cell stage. He found that such cells could also
give rise to whole larvae, Taut of correspondingly diminished
size. So far then, as the sea-urchin is concerned, taking
the facts at their face value, the cells of the very young
embryos were proved to be diametrically the opposite in
their relation to the complex as a whole, from the individual
stones of a mosaic work.

Driesch's methods of treating developing eggs were soon
much resorted to by other investigators, with the general
outcome that numerous animals in widely separated parts
of the animal kingdom were proved to have much the same
developmental ability as the sea-urchin. Wilson found that
the cells of Amphioxus embryos separated in the two- and
four-cell stage would develop from the very he ginning after
isolation like whole eggs of reduced size. It will be recalled
that the sea-urchin cells separated by Driesch developed
at the beginning like half-eggs, and only changed over to
the whole-embryo in the blastula stage. So Wilson's dis-
covery removed Amphioxus still farther from the mosaic
type of development than the sea-urchin had been removed
by Driesch.

The Italian zoologist, Raffaello Zoja, increased knowl-
edge of whole-animal production from a portion of the cells
of the young embryo, by showing that in the hydroid Clytia
ftazidula, not only one of the blastomeres from the two-cell
stage, but one from the four- and eight- and even the six-
teen-cell stage, will develop to complete organisms of dimin-
ished size, the half and the fourth at least, of the whole egg,
being capable of going on with the development until the
adult animal, perfect except as to size, is reached.

In view of the fact that the egg of the frog, a representa-
tive of one of the two main sections of the Amphibia (the

Further Examination of the Cell-Theory 205

anura), served as the starting point for the mosaic theory,
it is particularly interesting to know that the Qgg of Triton,
which represents the other section (the urodela), falls in
with the sea-urchin, Amphioxus, and hydroids, as concerns
the developmental abiHty of tlie separated cells of the two-
cell stage. For this information we are indebted first of all
to Amedeo Herlitzka.

This power of devclo])ing whole animals from portions of
the Qgg has been proved to exist in several other groups,
but enougli detail has now been adduced to show conclu-
sively that the mosaic conception of the organism contains
only a modicum of truth. The observations here briefly set
forth, with others of like import, led Wilson to declare : "In
its original form the mosaic theory has, I believe, received
its deatli-blow." "•

Going still farther, Wilson said in the same discourse,
"I will here point out one all-important point which is defi-
nitely established by the work of Driesch and other experi-
mentalists, and which is accepted by all opponents of the
mosaic theory, namely, that the cell cannot be regarded as
an isolated and independent unit. The only real unity is
that of the entire organism, and as long as its cells remain
in continuity they are to be regarded, not as morphological
individuals, but as specialized centres of action into which
the living body resolves itself, and by means of which the
physiological division of labor is effected." *^

It was these discoveries, antithetic to those which led to
the mosaic theory, that begot in Driesch's mind the concep-
tions of "totipotence," "prospective significance," and the
"harmonic equipotential system."

The formal definition of "totipotence," and of "prospec-
tive significance" may be given here since they concern pri-
marily the cells of the embryo. "Totipotence [is the pos-
session by] a part of the germ as yet not at all or but
slightly 'specified' of a form-producing power similar to that

206 The Unitij of the Organism

of the entire ^gg. It is therefore the power [of such a part]
to develop the entire organism." ^

The meaning of "prosi^ective significance" is that "each
blastomere is a function of its position in the whole." ^

The extreme form of Driesch's view is set forth in his
lucid and often quoted statement that the early cells of
the sea-urchin embryo are "composed of an indifferent ma-
terial, so that they may be thrown about at will, like balls
in a pile, without the least impairment of their power of
development." ^

Balancing the Account Beti&een the Mosaic and Totipotence

Theories

Every one, it would appear, must then admit that, so far
as concerns the part of the cell- theory which would see in
the cell the "key" to all development, these discoveries by
Roux and Driesch neutralize each other. If the cells of
the frog's egg seem in their individual capacities to produce
each its particular part of the organism, those of the sea-
urchin's egg seem, with equal positiveness, to do nothing of
the sort, but on the contrary to be entirely subject to the
needs of the future organism. This, I say, is manifestly the
effect which the original discoveries of Roux and Driesch
have upon each other. But later researches have undoubt-
edly proved that more animals resemble the sea-urchin than
the frog so far as the developmental attribute is concerned.
And the case of Triton, the near relative of the frog should
be particularly remembered. "There is no necessity," says
Herlitzka, "for a predisposition of various parts of the
isolated blastomere (or of the egg) to give origin to de-
terminate organs." ^"

It is quite impossible and unnecessary to follow all the
details of the Rouxian and Drieschian views of the relation
of cells to the organism in development ; but we must notice

Further Examination of the Cell-Theory 207

in a general way the course pursued by Roux relative to the
observations by other biologists and by himself which are
clearly hostile to the mosaic theory. To meet the fact that
under some conditions, even in the frog, not a half-embryo
but a smaller whole embryo develops from the isolated blas-
tomeres, he advanced the notion of "postgeneration." By
this he means the '''supplementary restoration, completely
or incompletely, of a half- or quarter-embryo, or other
'Partial-product' formed in consequence of the destruction
of a part of the cgg.^^ ^^

By coupling this idea with an earlier speculation of his
about the nature of the cell nucleus, he tried to make the
nucleus, instead of the cell, the really responsible element
in the mosaic, at least in those cases in which the whole cell
clearly does not conform to the mosaic conception.

Provision for retreat to the nucleus upon occasion, is
made in his definition of mosaic theory already quoted.^ It
will be recalled that the theory rests on the "assumption
of different qualities in the individual cells (cell body or
cell nucleus, etc.) capable of self differentiation."

Alongside this modification of the original mosaic theory
made by transferring the role of building stones from the
cells to the nuclei, it is instructive to place what is in effect
another modification of an opposite nature invented by G.
Born, in connection with his extensive experiments on graft-
ing together the larvae of various amphibians. Born found
that larvae, not only of different species, but even of diifer-
ent genera and families, could be made to unite to some
extent, the union between the more closely related species
being in general the easiest to accomplish and the most per-
manent, but that in any case each component of the grafted
specimen maintained its specific attributes uninfluenced by
the individual with which it was united. In other words,
animal grafts, so far as these experiments went, follow the
well known rules of plant grafts. The maintenance of iden-

208 The Unity of the Organism

tity of the parts, Born interprets as supporting the mosaic
theory. He says : "From our beginning stage on, the de-
velopment rests essentially upon self-differentiation of the
particular (einzelnen) parts a correlative influence of the
neighborhood (Nachbarshaft) as of the whole cannot be
recognized — neither negative nor positive ; the development
therefore corresponds throughout from our beginning stage
on to the mosaic theory of Roux. The organ-forming germ
regions are parceled out (His)." ^^

That an individual plant or animal made up of parts of
the bodies of two or more other plants or animals grown
together, each constituent maintaining its identity wholly
unmodified by the other parts, has as much resemblance
to a mosaic picture as can well be imagined for any living
being, must be granted. No one should, however, fail to
see the difference between a mosaic of this sort and one of
the sort conceived on the basis of the developmental facts
which were the starting point of Roux's theory. In the first
place "mosaic pictures" of the kind produced by grafting
are genuinely man-made affairs. They never occur in na-
ture. A "mosaic theory" contributes nothing substantial
to their interpretation. Indeed it is difficult to see that
there is room here for any such tlieory. Such a composite
creature undoubtedly resembles somewhat a mosaic picture
and that would seem to be all there is to it. But undoubted-
ly such a creature also differs very much from a mosaic pic-
ture. For one thing, the creatures are alive and mosaic
pictures are not. However, I have no wish to make all that
might be made against the mosaic theory because of its higli
degree of artificiality. The main purpose in bringing for-
ward Born's work and ideas at this point is to direct atten-
tion to his proposal touching what might be called the
scientific aspect of the mosaic theory. The organ-forming
germ areas (organbildende Keimbezirke) of His to which
Born refers, and which unquestionably played a large part

Further Examination of the Cell-Theory 209

ill Roux's original theory, are surely features of the earliest
stages of ontogeny, even of tlie unsegmented ^gg- A passage
from His's Unsere Korperform quoted by Wilson makes this
clear. "The material of the genn is already present in the
flat germ-disc, but is not yet morphologically marked off
and hence not directly recognizable. But by following the
development backwards we may determine the location of
everj' such germ, even at a period when the morphological
differentiation is incomplete or before it occurs ; logically,
indeed, we must extend this process back to the fertilized or
even the unfertilized Qgg. According to this principle, the
germ-disc contains the organ-germs spread out in a flat
plate, and conversely, every point on the germ-disc reap-
pears in a later organ. I call this the principle of organ-
forming germ-regions.^* ^^

But notice now that the organ-forming germ-regions
which were Born's "beginning stages" in his grafted larvae,
were by no means "germ-regions" of the unfertilized or even
fertilized ^gg. They were parts of larvae, i.e., of individual
animals well advanced in development. The pieces in his
mosaic works were not single cells or parts of cells but great
groups of cells, many of them already considerably differ-
entiated from one another, but yet so correlated in their
activities as to enable the grafted parts of the animal to
maintain their specific identity.

A fundamental question, then, raised by the mosaic theory
as formulated to-day is. What is an organ-forming germ
area.? or, more briefly. What is germinal material.'^ Is it
the material of each of the first two, or in some instances
four blastomeres as indicated by the frog's ^gg? Is it
nuclear material as conceived by Roux's modification of his
original theory? Or is it in accordance with Born's idea,
the material of any group of cells no matter how large the
group and how many kinds of cells in it, so long as the
group is able to develop true to the kind of organism to

210 The Unity of the Organism

which it pertains? A critical examination of both the orig-
inal theory and the modifications of it, in the light of the
questions just raised will, I believe, discover that the modi-
fications have in reality destroyed whatever of scientific
value the original theory may have had. There can be no ob-
jection to comparing a living being with a mosaic picture on
the basis of the fact that the former is composed of a great
number and variety of living particles called cells, just as
the mosaic picture is composed of a great number of par-
ticles of stone, but the comparison has at best but little
scientific value, and at worst may be very harmful. The
little scientific value in the comparison is purely subjective
and logical; it concerns the problem of the unity in spite
of the composite qualitj^ of both organism and picture as
objects of perception.

The harmfulncss of which the comparison is capable lies
in the wholly fallacious inferences that may be drawn as
to the mode of origin of the objects compared. The funda-
mental difference between them is that while all the myriad
cells of the organism arise by the repeated auto-division of
one cell, the fertilized ovum, the picture is composed of
pieces of stone cut one by one from rocks which had noth-
ing to do with it, until the pieces were assembled and put in
order to produce it, by men, beings again originally quite in-
dependent of the picture. The undivided egg-cell would then
have to be compared to one such stone block, and a moun-
tain of trouble looms up. In the first place, we know for an
absolute certainty that there is no one block of the pic-
ture from which all the others are produced either by divi-
sion or in any other way ; and in the second place, while
any particular stone block of the picture is nearly or quite
homogeneous so far as the general design of the picture is
concerned, and represents only a small piece in the design,
the undivided egg-cell is itself the whole organism in one
stage of its growth, and contains within itself a consider-

Further Examination of the Cell-Theory 211

able dcsif^-n, or composition ; so much, that is, as is distinc-
tive of the organism in this period of its Hfe.

Nor can Ave let Born's modification of the theory off
without looking at it from another and quite different angle.
The larvae and portions of larvae entering into the graft ,
complexes have, he shows, no correlative influence on one
another, nor is there any influence of the whole on the parts,
and therefore the whole is a mosaic work. But how about
the cellular and tissue elements composing the larvae and
part's of larva? within the complex? May we look upon these
elements also as comparable to stones in a mosaic picture.'^
Is not the fact that the portions of an organism entering
into a graft-complex maintain their specific If not individual
identity, peculiarly strong evidence of correlative influence
of the elements of these portions upon one another.^ The
organized and organizing power of living beings hardly
manifests itself in any way more strikingly than in the
fidelity of grafts to their own kind whether In plants or
animals. But the very essence of organization and organ-
izing power is, as everybody recognizes, correlative in-
fluence or activity. A mosaic picture Is about as near an
antithesis to an organization as can be found. So while
we may willingly grant that an organism made up of parts
of other organisms grafted together resembles to some ex-
tent a mosaic work, we must at the same time recognize
that when looked at in Its real nature it not only does not
support, but really refutes the mosaic theory if that theory
is held to any definite and significant meaning.

The ^^Promorphology"' of Germ-Cells

Although a critical examination of the mosaic theory
found it to be of exceedingly little value at its best, and
downright noxious at its worst, yet we were led to recognize
a measure of foreordlnatlon in each gf the first two cells

212 The Unity of the Organism

of the dividing egg, as in that of the ctcnophore, and under
some circumstances, the frog. Even before division begins,
this intimation of specific structure of the Qgg arrests our
attention. Our standpoint makes organization important
wherever found and of whatever grade.

(«) Facts of Immediate Ohservation on Which the

Conception Rests

The truth is we now know that the undivided egg-cell
stage, in the individual life histories of animals so far as
they have been carefully studied, is already rather highly
organized and to a considerable extent specificaUy organ-
ized with reference to the kind of organism which the egg-
cell represents. Otherwise stated, we know that a thorough-
going account of the life history of any organism must in-
clude its structure and function in and before the undivided
egg-cell stage, as well as its structure and function after
cell-division begins. The science of germ-cell structure and
function previous to the egg-cell division is known to embry-
ologists as promorphology and prophysiology.

The inductive evidence in support of the conceptions of
promorphology and prophysiology is altogether too volu-
minous and complicated to be fully presented in a work
like this ; but the matter is so important that the reader
must not be left in doubt about its conclusiveness.

I call attention first to an aspect of the evidence which
though well known in a general way, is rarely if ever given
the consideration which in my opinion it merits. Reference
is made to the fact that many species of animals, even be-
longing to the same genus in numerous cases, have been
distinguished from one another in all their stages of de-
velopment down to the undivided egg-stage. Investigation
has gone so far in this direction as to make it probable that
ftU species whatever might be thus distinguished were thQ

Further Examination of the Cell-Theory SU^

examinations sufficiently searching.

Tlie most extensive studies in this field have pertained to
groups of animals whose economic or ecological relations
to man are such as to render it important to recognize the
different stages of their lives. Thus in the interest of the
great marine fishing industries of northern Europe, elab-
orate investigations have been undertaken for identifying
the eggs and embryos of numerous species of fishes. Worthy
of special consideration is the partnership work by Fr.
Heincke and E. Ehrenbaum.

After asserting the indispensability of exact specific de-
termination of floating eggs and young fishes as a basis for
any reliable deductions concerning the distribution of the
eggs, the authors say that the possibility of such deter-
mination can be affirmed only conditionally ; and their re-
search had for its object to show in general how far the
identifications can be made, and in particular to ascertain
the extent to which size is distinctive of the different species.
Agreeing with seemingly all zoologists who have attended to
the matter, they say that the oil drops and pigmentation
occurring in so many floating eggs furnish important dis-
tinguishing marks. The time of escape of the embryo from
the Qgg membrane seems also to be distinctive for many
species. Concerning pigment, they affirm that in the ad-
vanced embryonal stages, nearly all fish species can be rec-
ognized with great certainty. Included in the elaborate
study is a "table for determining the floating fish eggs in
the German North Sea." ^^ This is a "key" in the ordinary
sense of the taxonomist and deals with some thirty species
belonging to about twenty genera. The attributes used
chiefly in constructing this key are found in the oil drops,
pigment spots, and size of the eggs.

Mosquitoes are another group of animals which have
drawn considerable attention to their early developmental
stages because of their importance to man; and here again

Si 4 The Vnity of the Orgnmsm

"keys" for the identification of the species are frequently
given for the larv^ae as well as for the adults. I have seen
no work on the subject in which the eggs are treated in this
diagnostic way, but in the ''Report of the Nem Jersey State
Agricultural Eocperiment Station upon the Mosquitoes oc-
curring within the State, their Habits, Life History, etc.""
by Dr. John B. Smith, we read, ''Dr. Dupree tells me that
he has found good characters in both eggs and larvse; but
that they are observable only with the compound micro-
scope." ^^

The truth arrived at in other connections from more
theoretical considerations, that the fertilized agg from which
an individual animal develops is that individual in the one-
cell stage of its life, comes most vividly to view in just these
purely practical studies. Thus in one of the many reports
by Fr. Heincke on the food fishes of the North Sea, the
author says : "The first condition for a right understanding
of the habits and habitats of the food-fishes of the sea, and
in general, of the production of the sea as regards useful
fishes, is an exact knowledge of the occurrence and dis-
tribution of these food-fishes at all the various stages of
their life, from the egg on to the adult mature form.'* ^^

Facts of the sort here set forth have seemed to most biol-
ogists too trivial to deserve consideration in theoretical
discussions, and so far as they have been studied, this lias
been done for the most part either incidentally, or, as in
the cases here adverted to, for practical ends.

(/>) Grounds for Believing Minute Observable Specific
Differences Betxeeen Germ-Cells Important

No matter how minute and superficial may be the at-
tributes which distinguish the egg-cell stages of species,
if these attributes are indubitable and constant they differen-
tiate the species in that stage of the individuals* lives, and

Further ExnmiTiation of the CcU-Theory 215

so from the strictly logical standpoint have the same order
of importance as have smaller discriminative attributes of
any other stage in the individual life ; furthermore, from all
that modern research is bringing to light on the correlation
of attributes, to assume that these minute differences are
really as detached and insignificant as they seem is biologi-
cally quite unwarranted.

To illustrate, what careful biologist would dare affirm,
having due regard for what we now know about the chemical
interaction of the parts of an organism, that the difference
in the size and distribution of the oil globules, let us say,
of the eggs of two species of fish, stops with just that dif-
ference? We are certain, are we not, that the formation of
these globules is connected in some way with the metab-
olism of the ^gg^^ And this means that the truly living
substance and vital processes of the egg are involved. So
it becomes not only possible but highly probable that oil-
drop differences between the eggs are indices of far more
deep-seated differences.

And we must not fail to note that in addition to the
probability of important correlations among these seem-
ingly trivial morphological details through the metabolism
(i.e., through the chemical processes) of the cell, correla-
tions through the physical processes are also to be pre-
sumed in accordance with the conceptions of the cell justi-
fied by physical chemistry. The reader should recall the
quotations from Hopkins on the conception of the cell as a
system in equilibrium. But an additional statement from
the same author will be especially germane at this point.
Speaking of certain metaplasmic constituents of the cell,
Hopkins writes : "These last comprise not only the fat
droplets, glycogen, starch grains, aleurone grains, and the
like, but other deposits not to be demonstrated histologi-
cally. They must be held, too, — a point which has not
been sufficient!}^ insisted upon, to comprise the diverse sub-

216 The Unity of the Organism

stances of smaller molecular weight and greater solubility
which are present in the more fluid phases of the system —
namely, the cell juices. It is important to remember that
change in any one of these constituent phases, including
the metaplasmic phases, must affect the equilibrium of the
whole cell system, and because of this necessary equilibrium-
relation it is difficult to say that any one of the constituent
phases, such as we found permanently present in a living
cell, even a metaplasmic phase, is less essential than any
other to the 'life' of the cell, at least when we view it from
the point of view of metabolism." ^^

Biology will sooner or later surely have to take seriously
in hand this matter of the differences between organic spe-
cies in all the stages of the lives of the individuals repre-
senting those species, the germ-cell stages with the rest.
There is urgent need for the extension of ordinary taxono-
mic investigations to the entire ontogenetic series of organ-
isms, the germ-cell stages included. Such work as that
by Dr. Th. Mortensen on the comparative larval stages of
echinoderms is in this direction and should be far more
widely prosecuted than heretofore.

The classical systematic studies of Gustav Retzius on
the spermatozoa of the animal kingdom are on the whole
the most complete we have in this field; but it must be re-
membered that the differential attributes of species at this
level are likely to have somewhat less correlational sig-
nificance than similar attributes of the eggs, for the reason
that the sperm-cells are more highly differentiated for their
special environment and habits and offices. We may confi-
dently predict extensive researches in the future on the
taxonomy of germ-cells according to the frankl}'^ descrip-
tive standpoint, and on the promorphology of germ-cells
according to the morphological standpoint.

The term promorphology has usually been restricted to
a very different use from that to which I have here put it.

Further Examination of the Cell-Theory 217

namely, to structural features of the ovum which influence
the early stages of cell-division, and the shape, size, struc-
ture and so forth, of the "blastomeres," i.e., the product
of the early egg-cell divisions. These phenomena have been
considered more significant than the differences between
eggs of different species above referred to, and have been
investigated by embryologists rather than by systematists ;
and it is to a large extent on evidence from this source that
the fact that the '''^gg is not one being and the embryo
another and the adult a third, but the Qgg of a human being
is a human being in tlie one-celled stage of development" ^'^
has gained theoretical interest.

Several of the most thoughtful embryologists who have
investigated the earliest stages of numerous animals by the
best modern methods have expressed views more or less
like this, and so are in accord with zoologists who have
been led to the comparative investigation of eggs by prac-
tical considerations.

A quotation from E. B. Wilson will serve well as a start-
ing place for our inquiry as to what promorphology is in
this restricted sense. "It is a remarkable fact," writes
Wilson, "that in a very large number of cases a precise
relation exists between the cleavage products and the adult
parts to which they give rise; and this relation may often
be traced back to the beginning of development, so that
from the first division onward we are able to predict the
exact future of every individual cell. In this regard the
cleavage of the ovum often goes forward with a wonderful
clocklike precision, giving the impression of a strictly or-
dered series in which every division plays a definite role
and has a fixed relation to all that precedes and follows it.
But more than this, the apparent predetennination of the
embryo may often be traced still further back to the regions
of the undivided and even unfertilized ovum." ^^

This preordination of the future animal in the egg before

218 Tlic Unity of the Organism

the beginning of development, strictly understood, about
reaches its zcnitli among the insects. According to W. M.
Wheeler, a Frencli investigator, P. Hallez, states the mat-
ter thus with reference to the cockroach, water-beetle, and
locust : "The egg-cell possesses the same orientation as the
maternal organism that produces it : it has a cephalic pole
and a caudal pole, a right side and a left side, a dorsal
aspect and a ventral aspect ; and these different aspects
of the egg-cell coincide with the corresponding aspects of
the embryo." -" "My obserAations," Wheeler says, "based
on some thirty different insects, accord perfectly with those
of Hallez ;" and lie adds as details that the head end of
the future embryo is usually marked by the micropyle and
that the dorsal and ventral sides are foreshadowed by a
slight flexure of the elongated Qgg in its longitundinal axis,
the concave surface of the oigg corresponding finally to the
dorsal side of the embryo. To understand more specifically
the meaning of this for the point under consideration, it
is necessary to have in mind that such insect eggs as
Wheeler is talking about are largely yolk, so far as bulk
is concerned, and that the very young embryo arising from
division of the protoplasmic part of the Qgg occupies but a
relatively small portion of its whole surface. This small
embryonal patch or blastoderm, after it begins to elongate
and to show traces of the jointed body of the adult insect,
is called the germ-band. "The practical value of Hallez'
law," Wheeler says, "was shown in studying the Xiphidmm
[a locust] ^gg\ all the movements of the germ-band could
be at once referred to the axis of the mature embryo. When
the eggs of other insects are oriented in the same manner,
it is seen that the germ-band invariably arises on the ven-
tral surface of the yolk with its procephaleum directed to-
wards the cephalic, and its tail toward the caudal pole.
No matter what positions it may subsequently assume, it
always returns to its original position before hatching." ^^

Further Examination of the Cell-Theorij 219

This statement about the movements of the germ-band has
reference to the fact that the actively developing part of
the Qgg makes a series of remarkable journeys, as one
might say, within and upon the rest of tlie egg, wliich con-
sists mostly of yolk. In other words the topography and
orientation of the very young insect are so far and so firmly
established before cell multiplication begins that the details
of cell splitting and cell movement and arrangement have
seemingly little or no Influence in determining these rela-
tions, but on the contrary, tliough going on for a time
quite independently of such relations, are finally brought
into conformity with them.

In another group of animals, those to wliich "pill bugs"
and "sow bugs" belong, the eggs, like those of insects, con-
tain a great quantity of yolk but the protoplasm is sharply
separated into two portions, the one superficial and non-
nucleated for a time, the other deeply imbedded in the yolk
and nucleated. Only the centrally situated nucleated por-
tion undergoes division at first. This division is so thor-
oughgoing that the resulting cells, the blastomeres, become
widely separated from one another and scattered through
the yolky part of the ^gg. Later these scattered blasto-
meres migrate into the surface patch of protoplasm and
uniting with it form the blastoderm, the forerunner of the
embryo proper. Investigating this mode of development,
J. P. McMurrich emphasizes the fact that all details
of cell-formation and migration and final arrangement have
reference to structural peculiarities some of which are pres-
ent before cell multiplication begins, while others pertain
only to the later embryo. Both the direction taken by the
spindle of the dividing nuclei, and the aggregation of the
blastomeres in the surface layer of protoplasm are, says
McMurrich, "simply precocious preparations for a differen-
tiation which will later become pronounced ; they refer to the
final form of the embryo, and are instances of Sachs' law

220 The Unity of the Organism

that growth determines division and not division growth." ^^
And the author continues : "Each stage of the development
appears to stand in relation not only to what has preceded
it, but to what will succeed it, and is a link in a chain one
end of which is lost in the obscurity of the past while the
other stretches into the future." And still further: "We
must, I believe, recognize the fact so forcibly discussed by
Dr. Whitman in his lecture on the Inadequacy of the Cell-
Theory of Development and so clearly shown by centro-
lecitlial ova, that in embryological development the differ-
entiation which occurs is a differentiation of the entire or-
ganism and not of the constituent parts or cells of which
it is composed ; physiologicall}^, if not morphologically,
every organism is a syncytium, and future theories of
heredity must take this into consideration."

I will do no more in the way of comment than to call
attention to the fact that the phrase "in embryological
development the differentiation which occurs is a differentia-
tion of the entire organism and not of the constituent parts
or cells," is one Avay of expressing specifically my general
proposition that the organism is an explanation of its parts
or cells.

While the element alist may admit himself compelled to
grant that in animals having eggs of the type dealt with
by Hallez, Wheeler and McMurrich, i.e., eggs of the insect
type, the organism seems as mucli a causal explanation of
the cells as the cells are a causal explanation of the organ-
ism, he will be likely to say tliat eggs of this type are rather
the exception than the rule, taking the whole animal king-
dom into account, and hence that the cases cited do not
justify a sweeping generalization of the sort I am trying
to establish as to the causal power of tlie wliole over the
parts in organic development.

We nmst consequently consider liow tills matter stands
with animals generally. Attention may first be called to

Further Examination of the Cell-Theory 221

Wilson's statciiient already quoted, that "it is a remarkable
fact that in a very large number of cases a precise relation
exists between the cleavage-products and the adult parts
to which they give rise." ^'^ The frog's egg, one of the
earliest and most persistently studied of all eggs, was long
ago discovered to have certain features about it, even before
cell-multiplication set in, that are adumbrative of the struc-
tural relations of tlie future embryo and adult. This was
partly recognized, as Wilson points out, by Karl Ernst Von
Baer, the "father of Embryology" ; and the fact that the
first division plane of this egg corresponds with the plane of
symmetry of the adult frog was discovered more than a
lialf century ago by George Newport.

Another group of animals in which promorphology in
this restricted sense is quite as conspicuous as in the groups
already mentioned is the mollusca. Especially note-
worthy are molluscs of the octopus kind. A research in
this field well known and much admired among embryologists
is by S. Watase on the common squid. Wilson epitomizes
Watase's results touching this matter as follows : "Here
the form of the new-laid egg, before cleavage begins, dis-
tinctly foreshadows that of the embryonic body, and forms
as it were a mould in which the whole development is cast." "^

Watase's own statements are peculiarly instructive since,
as is well known to biologists, he has been an extremist on
what we might call the aggregative theory of the multi-
cellular organism. The fact of a definite organization of
the squid in the one-celled stage of its life he fully recog-
nizes. This organization is, he says, such "that the plane
of the first cleavage furrow may coincide with the plane of
the median axis of the embryo, and the sundering of the
protoplasmic material may take place into right and left,
according to the pre-existing organization of the egg at the
time of cleavage ; and in another case the first cleavage may
roughly correspond to the differentiation of the ectoderm and

S2S The Unity of the Organism

endoderm, also according to the prc-organized constitution
of the protoplasmic materials of the ovum." '^^ How is this
organization of the squid before cell multiplication begins
to be explained in accordance with the conception that
the creature's cells are more fundamental than the creature
itself and are the cause of the creature? Watase's radical
elementalism made it almost obligatory upon him to try to
answer the above question. Something of the difficulty which
the protozoan colony theory of the higher organism has to
face in such cases as this, he seems to have felt, and his way
of meeting it certainly has the merit of being ingenious.
"Even if we admit," he says, "that the unicellular ovum
irrespective of its stages of growth, represents actually the
condition of the ancestral protozoan, a highly differentiated
axial symmetry of a certain metazoan ovum cannot be said
to be an aberrant feature unrepresented in the ancestral
protozoa, so long as the existing forms of the protozoa
often show such a high degree of differentiation in that par-
ticular respect." ^^ As though the high degree of axial
differentiation in some protozoan imagined to be the far-
away ancestor of a squid were an explanation of the axial
differentiation of a squid in its unicellular stage ! It is
hardly possible for speculation to soar on less restrained
wings than this and maintain its claim to being scientific.

So much by way of illustration of animal groups in which
the promorphology consists in a considerable measure of
observable differentiation while the individual animal is yet
in the one-celled state, or, in other words, of animals in
which the individual development has gone some distance in
the Qgg before cell multiplication begins.

(c) Re-flections on a Promorphology of Germ-Cells Beyond

the Limits of Visibility

To make the generalization that the egg is an individual
animal in the one-celled stage of its life, we have now to

Further Exavdnation of the Cell-Thcorij 223

consider those animals in wliicli the egg- does not observably
foreshadoAV the adult by any such axial or other differen-
tiations as do those we have just been considering. Eggs
of this sort, of which tliose of the sea-urchin and amphioxus
are examples, are preeminently the ones called totipotent
by Driesch. Reference to what was set forth in our dis-
cussion of totii:)otence will bring before the reader the fact
that eggs of this kind look to be quite devoid of organiza-
tion forecastive of the adult stage, but yet are so profoundly
stamped in some way with the nature of the species that
not only the undivided egg-cell may develop into an adult
animal, but each of the first two or four or in some cases
even eight blastomeres, may develop into complete animals
if the blastomeres be entirely separated from one another.
All analogy of observable structure and development war-
rants us in believing two things as to the promorphology of
these eggs ; first, that there is some sort of organization
characteristic of the species to which the particular animal
belongs beyond the limits of our present knowledge, and
second, that we have little or no means of predicting what
that organization is. This second point is of much im-
portance from its involvement of embryological specula-
tions on the nature of the germ. The fundamental fact
lost sight of in almost all these speculations is that the
transformations and metamorphoses characteristic of all
organic development are in their very essence unforeseeable.
The history of biology, and especially of comparative em-
bryology, is absolutely conclusive on this point. Over and
over again has it happened that certain developmental
stages in the life cycle of animals have been discovered be-
fore the complete seines of stages were known, and that these
stages were so different from the adult stages that the pre-
dictions made as to the species to which the stages belonged
were entirely wrong. The larva of Balanoglossus is a fa-
mous instance of this in the history of zoology. This larva

224 The Unity of the Organism

resembles the larva of eiichinoderms so much that its dis-
coverer believed it to belong to this group and for a long
time zoologists accepted this view, the truth about it com-
ing out only when the transformation of the larva into the
adult was actually observed. For non-zoological readers
it may be stated that Balanoglossus is a worm-like creature
about as unlike a sea-urchin or a starfish as can be im-
agined. The truth is, it is only by ohservational compara-
tive studies that embryologists are able to predict at all
either the earlier or the later unobserved stages, pertaining
to the developmental career of an animal.

If speculation on the nature of germ-cells had followed
consistently these familia.r and universal principles, the
literature of biology w^ould be unburdened to-day of a vast
load of useless writings. Let any biologist ordinarily prac-
ticed in the methods of embryology ask himself candidly
what he would expect to find in the living fertilized Qgg of a
starfish, for instance, were some manufacturer of micro-
scopes to furnish him with an instrument that would mag-
nify with good definition to a million diameters. Can he
consistently suppose he would see something "carrying" all
the innumerable characters of the adult starfish.'^ Why has
he any more right to suppose he would recognize the char-
acters of the adult in the germ-cell than that he can recog-
nize them in the larva just before metamorphosis, or in any
other stage? Yet what embryologlst has ever talked about
the characters of the adult starfish being "carried" by ele-
ments of the larva? What we are justified in believing on
the basis of the inductive evidence in our possession is that
such a microscope would enable us to recognize many struc-
tural features peculiar to the particular species of starfish
at that particular stage of the individual's life, and that as
development proceeded these egg-stage features or char-
acters would disappear and other characters distinctive
of the embryonal stage, the larval stage, and so on, would

Further Examination of the Cell-Theory 225

appear in regular succession till the adult stage with its
distinctive characters were reached. The great point to be
emphasized is that if we are guided strictly by the observa-
tional and rational methods by which all our knowledge of
organic development has been built up, we see that the ef-
fort to conceive germ-cell promorphology or prophysiology
in terms of representative units succeeds only in so far as
we deceive ourselves into believing that we know what we
do not know, and probably never can know, about the struc-
ture and functions of the germ, and b}^ thus deceiving our-
selves, believe ourselves relieved of the necessity of endeavor-
ing to leani what the actual structure and function of the
germ is.

The metaphysical promorphology and prophysiology of
the germ which, culminating in the "determinants" of Weis-
mann, have befuddled the thinking of many biologists, hold
exactly the same place in the logic of biology that phlogis-
ton held for well nigh a century in the logic of chemistry.
There is surely something in the wood that is a cause of
the flame, so why not say the characters of the flame are
"carried" in the wood by units capable of doing that sort
of thing? And how easy and complete the explanation of
flame would be on that basis ! For minds of such cast as
tliat of Joseph Priestley (about the last ardent defender of
phlogiston) and as those of Weismann and his disciples,
explanations of this sort appear to have great fascination.

It is probably implied, if not definitely contended, by
some present-day geneticists, that the methods of analysis
employed by them, those, namely, of experimental breeding,
the application of Mendelian principles of inheritance, and
the correlation of these with chromosomal studies, are a
refutation of the conceptions above set forth. As a matter
of fact, though, the results of genetical analysis, so far as
they are objective and not purely speculative^ are entirely
confirmatory of the conceptions.

226

The Unity of the Organism

REFERENCE INDEX

Roux
Roux

('12)
('12)

262
142

1.

2.

3.

4.

5.

6.

7.

8.

9.
10.
11.
12, Born 613

Crampton ('96) 1-26

Driesch ('07) 60

Wilson, E. B. ('93) 5

Wilson, E. B. ('93) 8

Roux ('12) 409

Driesch ('94) 12

Driesch ('93) 25

Herlitzka 653

Roux ('12) 311

13. Wilson, E. B. ('00) .... 398

14. Heincke and Ehrenbaum 294

15. Smith 160

16. Heincke 1

17. Hopkins 220

18. Conklin ('15) 102

19. Wilson, E. B. ('00) 378

20. Wheeler, ('93) 67

21. McMurrich ('94) 142

22. Wilson, E. B. ('00) 382

23. Watase 280

Chapter IX
ORGANISISIS CONSISTING OF ONE CELL

A. ADULT FORM AND STllUCTURE

Remarks on the Conception of the Cell as ari Element ary

Organism

WE saw early in the chapter on The Organism and its
Cells that the cell may be advantageously looked upon
as an "elementary organism." The warrantableness of thus
regarding it as set forth by Carl Briicke, who first clearly
reached the perception, should be recalled. This conception is
warranted, Briicke said, by the fact that the cell possesses
an organization of another sort than that pertaining to its
molecular structure. While we may not subscribe to the
implication of his doctrine that the cell has an organization
wholly independent of its molecular structure, yet we must
endorse his conception that it has a structure genuinely
unique as contrasted witli tluit of any non-living body; and
must reckon the perception of this fact as a forward step
of first rate importance in biology.

While we are now to devote a cha})ter to an inquiry into
that peculiar structure of the cell which justifies us in view-
ing it as an elementary organism^ we should recognize that
this discussion falls properly under the general head of
cell-theory taken in the comprehensive sense indicated in
chapter six. As there defined the cell-theory concerns itself
with the structure of the cell as well as with the participa-
tion of cells in the make-up of multicellular organisms. It

227

228 The Unity of the Organism

is only for the didactic purpose of making' this part of the
theory stand out in tlie discussion witli a prominence pro-
portionate to its importance that we give it independent
titular recognition. So our present discussion will intersect
at various points the discussion of the Cell-Theory specifi-
cally. The first intersection is at the place where we brought
out the fact that the conception "organism" is historically
jjrior to "cell," and hence, that in reaching the conception
of the cell as an elementary organism, Briicke and those who
followed him have literally used the organism to explain the
cell. We must now push this idea further in both its logical
and its factual aspects.

First as to the logic of it. When we state that the cell
is an elementary organism, we are speaking in the technical
language of logic, recognizing the cell as a species of the
genus organism. An elementary organism is obviously one
kind of organism, the implication being unescapable that
there are other kinds ; one other kind implied being a not-
elementary, that is, a more complex kind. Organism is a
broader and higher category than elementary organism, an-
other designation for cell. From the natural history stand-
point, then, Haldane's efforts to raise organism to the
dignity of a category in the Kantian sense are superfluous,
this having already been done in the real sense through the
establishment by Briicke and the acceptance by biologists
generally of elementary organism as a defining designation
for cell. This aspect of the logic of the cell-theory is of so
much practical importance that it is desirable to state it
more definitely if possible.

The term cell now universally accepted in biological ter-
minology is a general name applicable to a vast class of
natural objects, the name having become fully established
and defined after years of patient examination and descrip-
tion by many investigators, extending to the whole range
of objects brought under the designation. If one reflects

Organisms Covsistijuj of One Cell 229

on all this he will sec a vast difference of meaning in the
word cell when used in the two assertions: "this object un-
der the microscope is a cell," and such generalizations as
"the key to all ultimate biological problems must be sought
in the cell." In the first case the term performs the com-
paratively simple office of a name for a particular object,
endowed, as one might say, with great ability to make in-
telligible certain phenomena of living beings.

Undoubtedly the name stands for an idea in both cases,
and undoubtedly too, the ideas in the two cases must have
something in common, but equally certain is it that there
are important elements of difference in the two ideas. Of
the elements in common, one, we know very well, relates to
certain structural features, cytoplasm, nucleus, and so on,
experimentally settled upon as essential to any object en-
titled to be called a cell. Another is the conception that all
bodies so entitled arc a kind of organism, i.e., elementary
organism, this conception being based on the observation
that great numbers of cells are, in the language of O. Hert-
wig, "endowed with the attributes of life." Now notice:
by virtue of what is the cell conceived to be the key to all
biological problems.'^ Surely not in the mere presence in it
of bodies that may be called nucleus, cytoplasm, and so
forth, but rather because it is endowed with the attributes
of life, is an organism, even though of an elementary char-
acter. In other words, since typical cells are universally
admitted to be very simple in structure as contrasted with
those bodies to which the term organism was first applied,
and since it is now only one among such bodies, and that an
elementary and simple one, to assert that it is the "key to
all biological phenomena" is a logical contradiction, if by
being the "key" it is implied that the cell is an ultimate ex-
planation of such phenomena, for with such an implication
the assertion is virtually tliat part of a thing is greater than
the whole of it.

2S0 The Unity of the Organism

Comparison of the Structure of Organisms Consisting of a
Single Cell with That of Organisms Consisting

of Many Cells

This chapter will be concerned primarily with the factual
side of the structure of the cell viewed as a species of or-
ganism, and will confine itself to the structure of the cell
in organisms indubitably such in the strict sense, even
though they ordinarily consist of but a single cell.

The narrowing influence of elementalism in biology finds
striking illustration in the application of the cell-doctrine
to unicellular organisms, that is, to the protozoa and the
protophyta, or collectively, the protista. In fact, if one
wishes to bring before him in the clearest possible fashion
the contrast between what a great province of living nature
is when seen as it actually is and when seen through the
medium of elementalist theory let him compare some of the
great modern objective treatises on the protozoa, like Brady's
report on the Foraminifera and Haeckel's on the Radio-
laria, in the Zoology of the Challenger Expedition, or
Haecker's Tiefsee Radiolarien, in Wisse7ischaftliche Ergeh-
nisse der dewtschen Tief see-Expedition, with the statements
one finds in ordinary text books of zoology concerning the
same organisms. Hardl}^ anything could be more mislead-
ing than the almost universal practice in elementary teach-
ing of introducing beginners to the protozoa by showing,
very superficially, an amoeba and emphasizing its simplicity,
and then keeping it in the foreground of the learner's
thought as an exemplification of the doctrine that the pro-
tozoa are "extremely simple" animals, that they are undif-
ferentiated into organs and tissues^ — tliat in fact they are
hardly "true animals" at all. In even so advanced and usu-
ally excellent a work as Lang's Lehrhuch der vergleichenden
Anatomie we are told that the metazoa or "true animals"
{echte Tiere) are "set over against the protozoa or pro-

op.f.

ador.fn.-
o. odor lip...

o.pr-, • I

■circMcs.nng,

bcLl,-,

dxllsk.-.
ant.cilr:--
djtt.

/

FIGURE 1. DTPLODINTU^r ( AFTER SHARP ).

ador.m., adoral membranelles. an., anus. ant. oil. r., anterior ciliary
roots, ant.c.v., anterior contractile vacuole, bd.l., boundary layer
(ectoplasmic). cir.oes.r., circumesophageal ring. caec, caecum,
cut., cuticle, c.v.r., region about contractile vacuole. D., dorsal side
of body, d.disk, dorsal disk. d. furrow, dorsal furrow, d.m.str.,
dorsal motor strand, d.m., dorsal membranelles. ect., ectoplasm,
ent., entoplasm. fd.v., food vacuoles, i.ador.lip, inner adoral lip.
i.d.lip, inner dorsal lij). L., left side of body, l.sk.a., left skeletal
area, mac, macroiuicleus. mic, micronucleus. m.m., motor mass
(motorium). o.odor.fur., outer adoral furrow, o.ador.lip, outer
adoral lip. o.d.fur., outer dorsal furrow, o.d.lip, outer dorsal lip.
oes., oesophagus or cytopharynx. oes.f., oesophageal fibers, oes.-
retr.str., oesophageal retractor strands, op., operculum, op.f., op-
ercular fibers, or., oral opening, mouth, or cytostome. or.cil., oral
cilia, or, disk., oral disk, post.cil.r., posterior ciliary roots, post.c.v.,
posterior contractile vacuole. R., right side of the body, rect., rec-
tum, rect.f., rectal fil)ers. r.sk.a., right skeletal area, sk.lam., skel-
etal laminae, susp.f., suspensory fibers, V, ventral side of body,
v.sk.a., ventral skeletal area, n.m., nuclear membrane.

231

^S2

The Unity of llie Organism

tista," ^ the implication being that the protozoa are not
"time animals." "Organless organisms" is an appellation
one not infrequently finds applied to protozoa.

(«) Comparison of Certain CUiates and Metazoans

By way of introduction to the commentary I wish to make
on this mode of thinking, I ask the reader to compare the
pictures, figures 1 and S, keeping the idea of cell as much

cnt.cav.*

ms

FIGURE 2. HYDRA (aFTER PARKER AND PARKER).

ect., ectoderm. end., endoderm. ent.oav., enteric cavity. mth.,
mouth. hyp., hypostonie. msgl., mesogloea. ntc, nematocysts.
psd., pseiidopods. fl., tiagella. bd., buds, spy., spermary. ovy.,
ovary, ov., ovum.

FIGURE 4

FIGURE 3

FIGURE 4. STEXOSTOMA I.EUCOPS ( AFTER OTt).

c, cilia, c.p., ciliated pits, cu., cuticula.

b., brain, com., brain

commissure, d.o., dish-shaped organs, m., month, ph., pharynx,
ph.c, pharyngeal cells, e.c, epithelial cells, in., intestine, w.v.t.,
water vascular tube, r., rods, p., parenchyme. o.vv., external open-
ing of water vascular tube.

FIGURE 3. STYI.OXYCIIIA MYTILUS (fROM IIARTOG, AFTER LAXg).

a.c, abdominal cirrhi. an., anus discharging the shell of a Diatom,
c.c, caudal cirrhi. c.p., dorsal cirrhi. cv., contractile vacuole, e.,
part of its replenishing canal, f.c, frontal cirrhi. f.v., food vac-
uoles, g., internal undulating membrane. 1., lip. m., mouth or
pharynx, mc, marginal cirrhi. N., X., lobes of meganucleus. n, n,
micronuclei. o., anterior end. per., adoral membranellae. poc,
preoral cilia, p.om., preoral undulating membrane, s.h., sense hairs.

233

SS4 The Unity of the Organism

in the background of consciousness as though he had before
him for comparison a cat and a hen, for instance. Do the
figures give the impression that one presents a very simple
animal wliile the other represents a very complex one?
Which, may well be asked, is the very simple one? Does
one give the impression that it represents an organless ani-
mal, while the other represents an animal with organs?
Does one seem organized while the other is unorganized?
Does one look like a true animal while the other is an un-
true or pseudo-animal? Yet there is now unanimity among
zoologists that the creature represented by figure 1 is a
protozoan, while that represented by figure 2 is a metazoan.
The protozoan sliown is a species of Ciliate which inhabits
the stomach of the ox. Its techincal name is Diplodinium
ecaudatum. The figure is from R. G. Sharp. Figure 2
is of the common fresh water hydra.

Or compare in detail a Stylonychia, a protozoan, with a
Stenostoma, a worm. For the former, the description and
figure of Stylonychia mytilus, figure 3, given by Hartog in
the Cambridge Natural History will serve our purpose well.
A good description of a Stenostoma, figure 4, is furnished
by Ott. A rough and ready way of estimating the degree
of complexity of the two animals is to notice the number of
named parts or organs in the two descriptions, presumably
intended to be about equally thorough.

The activities of these two species have also been well
studied, so they can be compared from this as well as from
the anatomical standpoint. To any one who has watched
both creatures somewhat attentively in their normal lives,
the great animation and diversity of movement of the pro-
tozoan as contrasted with that of the metazoan are striking
enough. Concerning the general character of the movements
of Stylonychia, Hartog writes, "It moves through the water
either by continuous swimming or by jerks, and can either
crawl steadily over the surface of a solid or an air surface

Organisms Consisting of Ojie Cell 235

such as an air bubble, or advance by springs, which recall
those of a hunting spider." - The rapid movement ahead,
running against obstacles, backing off, clianging directions,
and turning around, remind one of the performances of an
ant under similar surroundings, flennings' statement that
they are "usually found running about on the bottom, or
on the surface of objects in the water," ^ is no more a figure
of speech than would be a similar remark about a rabbit.*

FIGURE 5. STYLOXYCHIA MYTILUS ( AFTER Pt'tTER).

With reference to their food habits, Maupas's characteriza-
tion of them as "hunter ciliates," is truly descriptive.

By contrast the movements of Stenostoma are slow and
simple indeed. In it locomotion is accomplished almost en-
tirely by surface cilia, and the well-nigh complete absence
of differentiation among these, as contrasted with the high
degree of differentiation and specialization of the cilia of
Stylonychia, may be taken as a reliable index to the dif-
ference in locomotor activities of the two creatures.

(h) Comparison of a Radiolarian and a Jelly-fish

Carrying the comparison of unicellular, "simple" or "un-
true" animals, with multicellular, "complex," "true," ani-
mals still farther, we will take up a Radiolarian for brief
consideration. Non-technical readers are particularly urged
to look througli tlie volume of 140 quarto plates which il-
lustrate Haeckel's great Challenger Report on tliis group.

* Jenninpjs copies this din gram from Piitter showing a Sfylonyrhia
"creeping- along tlie surface," uiiich sliows well the "belly" and the
"back" sides of the creature and the way in which it uses its cilia as legs.

S36 The Unity of the Organism

Nearly all large libraries have sets of the reports of this
famous exploring expedition.

So astounding was the wealth of life both as to number
of species and elaborateness of structure of the individuals
described and depicted in this report, that many zoologists
who had been properly impressed in their formal training
with the doctrine of the simplicity and minuteness of the
protozoa, were disposed for a long time to accept the re-
port with some "grains of salt" — -to suspect that many of
the specially remarkable species were, partly at least, crea-
tures of the lively imaginations of Haeckel and liis artist.
But later researclies, particularly those of V. Haecker, al-
ready mentioned, on the same animals collected on the cruise
of the Valdkia, of the German Deep-Sea Expedition, have
driven away all shadows of doubt about the essential truth-
fulness of Haeckel's narrations. Indeed, we now know, if
anything, he fell short of full justice to the Radiolarians.

I take this opportunity to remark that one of the serious,
even though perhaps unavoidable, defects of formal instruc-
tion in elementary zoology and botany is the tendency to
fix in the learner's mind the notion that nature is far more
simple than it really is. Of course, the only right antidote
for this falsification is contact with nature itself in its plen-
itude. But since school books and school lessons are main-
ly responsible for the wrong inculcuations, on the principle
that like cures like, books again, though this time of the
elaborate monographic sort, even though no more than
hastily run through, ought to be of considerable use to
young students. Quite as much with the hope of sending
the reader to Haeckel's or one of the other great mono-
graphs on the Radiolaria, as for the purpose of impressing
him with the elaborateness of organization of these animals,
I will refer specifically to a section of Haeckel's Report.

One entire new family discovered in the Challenger's col-
lections, Haeckel named Medusetta. Tlie author gives us

Organisms Consisting of One Cell 237

the reason for the clioice of this name : "Some species are
among" the most admirable forms of Radiolaria, and are simi-
hir to small elegant Medusae. The fonn of the shell ex-
hibits the same varieties as the similar umbrella of the
Medusa. . . . The similarity with the umbrella of a Me-
dusa is so great, tliat In many species the large lower open-
ing on the mouth of the shell Is surrounded by a prominent
ring or diaphragm, comparable to the velum of the Craspe-
dotae or Hydromedusae." * This general resemblance to
certain medusae is made still more striking in such a species
as Gazelletta crytonema bj the phaeodium, a mass of cell-
like pigment-bearing structures "in the lower half of the
shell cavity," ^ sometimes, as in the figure referred to, pro-
truding from the mouth of the shell. Xo one can compare
this figure with those of various medusae which bear gonads
or buds on the manubrium or the subumbrellar region with-
out being struck by the general resemblance between them.
The reader must not infer from this comparison that the
points of resemblance signify anything like close corre-
spondence in structure. As a matter of fact the two ani-
mals are no more alike than a bat and a butterfly. The
sole point of significance, so far at least as this discussion
is concerned, is that judged by the facts of actual structure
and function of the radiolarian and the coelenterate, the
first is hardly if at all more simple than the second — is not
a whit less a true animal.

{c) Comparison of the Shell of a Rhizopod and of a Xaatilus

One more comparison between a "simple" unicellular ani-
mal and a complex multicellular "true" animal is as far as
we can go in the strictly comparative-anatomy part of this
presentation. Take, for example, the shell of Operculina,
the detailed structure of which was worked out by W. B.
Carpenter. Some of the schematic figures in his work are

238 The Unity of the Organism

reproduced in many of the larger textbooks and handbooks,
Biitschli in particular giving specially good figures. The
remarkable resemblance of the shell of this and of allied
genera to the shell of the chambered nautilus has long been
a common subject of remark. According to the prevalent
view, although the variety and complexity of the shells of
great numbers of foraminiferae are universally recognized,
they do not militate against the conception of the animals
as "simple," because they are only secretory structures, or
in many groups only structures built up from foreign sub-
stances. But what right have we, I ask, to assume but slight
protoplasmic differentiation in a creature that can produce
in any way whatever such a system of chambers and septa
and canals and pores, as is presented by the shell of Oper-
cuUna? This query becomes particularly searching when
one considers that each of the various genera and species
has its own type of shell.

In his Monograph of the Foramimfera of the North Paci-
fic Ocean Dr. J. A. Cushman remarks that being single-
celled animals, the structures of the Foraminifcra "do not
need explanation on the basis of organs and tissues." ^ This
naive manner of dodging difficulties is characteristic of ele-
mentalist notions about explanation — the method of making
an implied theoretical definition take the place of searching
examination. The particular difficulty evaded by definition
in this case pertains to the nature of the outer portion of
the protoplasm or sarcodc, which constitutes so large a
fraction of the living body of both the Foraminifcra and the
Rhizopoda. As is well known, the sarcode produces the
shell either by secretion or by the selection and placement
of foreign particles. In many Foraminifcra, as Operculina,
the sarcode extends over the whole exterior of the shell,
thus making the shell an internal structure. The highly
elaborate canal and pore systems above referred to are
passage-ways for the semi-fluid sarcode.

Organisms Consisting of One Cell 239

Intimately connected with the network of sarcode situ-
ated within the substance of the shell and on its surface is
the wonderful pseudopodial system, i.e., the system of in-
numerable filamentous, anastomosing, expanding, withdraw-
ing, and shifting strands of living material. As is well
known, at least for many Rhizopoda, tlie pseudopodial sys-
tem is nutritional in function. First of all, the pseudopo-
dia are prehensile organs and operate in much the same way
and apparently with as great effectiveness as the corre-
sponding organs of higher animals. By means of them the
animals seize their prey consisting of living micro-organisms.
In some species the seizure is accompanied by a stunning
and paralyzing action. After capture the food is, in many
species, transported by the grasping organs through the
mouth of the shell and into the deeper portions of the sar-
code there to undergo digestion. But in some groups the
nutritional office of the pseudopodial system goes much
farther than the mere procurem.ent of food. Digestion, and
so of necessity circulation in part, are performed by the
same system. Calkins ^ mentions the Reticularia particu-
larly as Rhizopods whose digestion is thus performed. What
could be more far-fetched and distracting of attention from
the true nature of the animals, than to call organs that per-
form all these functions "feet," false feet, or feet of any
other kind.^

The locomotor appendages of many animals are brought
into the service of the nutritive function ; and in such ani-
mals, as many of the Crustacea, where this change of func-
tion has gone so far as to divert the organs entirely from
their original office and transforai them both structurally
and functionally into mouthparts, comparative anatomists
never think of still lumping them all together as locom,otor
organs. In no higher animal whatever, so far as I know,
has conversion of the locomotor into nutritional organs
gone so far as to make them not only food-seizing but food-

240 The Unity of the Organism

digesting, as is the case in the Reticularia. Consistency in
descriptive treatment and clear thinking demand that the
sarcode processes of those protozoans in which tlie struc-
tures are wholly or even chiefly nutritive in function should
no longer be called pseudopodia. Some such term as tro-
phorhiza ought to be applied to them, especially where, as
in the Reticularia, they are digestive. Whether or not
the structures "need explanation on the basis of organs and
tissues," they certainly need description and definition that
shall set forth their true nature. Fortunately considerable
study has been devoted to them and the rest of the peri-
pheral sarcode in the Rhizopods, and to the extra-capsular
sarcode of the Radiolaria, so we already know much about
the facts.

Calkins ^ has well summarized the information we possess
concerning the "pseudopodia" of Sarcodina. From this
knowledge we are able to say with the greatest assurance
that these creatures lead their lives — maintain their locus
in space, whether of fixity or movement, respond to external
stimuli, procure, ingest, digest, and assimilate their food,
solid and gaseous, and propagate their kind — no less defi-
nitely and hardly less variedly than the larger multicellular
animals. All these things they do through the instrumen-
tality of definite and definable anatomical elements ; and I
would insist that we can justify the refusal to call these
elements organs and tissues because they occur within the
limits of single cells only by having first so defined organ
and tissue as to exclude from them all organic elements not
composed of cells.

The Unjustifiahle Conception that Unicellular Organisms

Can Hare No Tissues

As a matter of fact this illogical course is exactly the
one that is widely followed. "A tissue is, therefore, a com-

Organisms Consisting of One Cell 241

plex of similarly differentiated cells." ^ This definition of
tissues, occurring In one of the most generally used text-
books of miscroscoj)ical anatomy, turns up in substance
again and again in tlie connnon instructional writings of the
day. "The foundation-stone of the tissue is the cell." ^^
According to this doctrine the cell is the building-stone of
the tissue, so no matter what may be found within the cell,
it cannot be a tissue, l^ndoubtedly this way of treating the
term tissue has been useful, especially didactically, and
undoubtedly too It is on the whole justified so far as multi-
cellular organisms are concerned, though even here 'the
scientifically scrupulous teacher finds himself under the
necessity of doing much uncomfortable wriggling to make
many of the connective tissues fit into it. But when the view
is extended to the whole animal kingdom, to the protozoa
as well as to the metazoa, one sees how inadequate and
cramping such a conception of tissue is.

The fact is, when we consider the real meaning of the
word tissue, and still further, w^ien we consider what the
anatomical parts are to which the early anatomists thought
the term could be appropriately applied, we see that with
the possible exception of some of the connective tissues
of the higher animals, we can hardly- point to a more typical
tissue than that of the network of strands into which the
peripheral sarcode of many of the Rhizopods forms itself,
or than the extra-capsular "plasm" of a Radiolarian like
ThalassicoUa. I mention this genus especially because a spe-
cies of it which has been well figured and described by Haec-
kel, is frequently used in text-books as a type of the group.
The "meshes constituting the sarco diet yum,"" the "alveoli
of the cal7/mma,*' and the pseudopodia arising in the deep
zone, or sarcomatrix and "forming a network through the
other capsular parts," are the terms in which the "plasm"
of these animals is described. And notice how contrary to
good biological usage it is to employ an anatomical nomen-

242 The Unity of the Orcfanism

clature wliich starts out by calling the major parts of the
body of this organism "plasm," and then names all the de-
tails of organization in keeping with this. It would be quite
as consistent and quite as useful to call all that part of a
fish, for example, situated outside the viscera "extra-vis-
ceral plasm/' and then name the skin, bones and muscles
"dermoplasm," "osteoplasm," "myoplasm."

True Organs in Some Protozoans

But objectionable as is the usual treatment of the term
tissue when viewed from the standpoint of a theoretical biol-
ogy that is adequate and generous, even more objectionable
is the treatment of the term organ. What could be more
absurd than to contend that an animal like Diplodinium (see
figure 1) has no true organs, while one like Stenostomum,
figure 4, has such organs ! No zoologist who becomes so
interested in any of the higher protozoa as to nse above the
theoretical notions into which he may have been schooled as
to what an organ is, hesitates to call many of the parts of
these creatures organs. Thus speaking of his discovery of
what he regards as functionally a supporting apparatus for
the gullet in an infusorian related to Diplodinium, A. Giin-
ther says : "I have found an organ lying in the ectoplasm.
. . ." ^^ Sharp's excellent description and illustrations of
this organ (or these organs, for there are three of them)
in Diplodinium, establish its indubitable right to be called
an organ.

Both historically and biologically there are two criteria
for an organ. One, the more important, is that a part
shall perform a definite office or function in the economy of
the organism ; the other, that it shall be composed of definite
elements to which usually the term tissues may be applied.
As to how the organ in question of Diplodinium measures
up to these criteria, we will let Sharp tell us. Concerning the

Organisms Consisting of One Cell 243

first he writes "That tlie above described structure functions
as a true skelatal (sup[)orting) structure, not only for the
retractile oesophagus, but also for the entire body, seems al-
together certain." ^^ The illustration shows something as
to its composition (figure 1 sK\ lam., indicating skeletal la-
minae). It is composed of plates or laminae, running length-
wise of the organ, and placed edgewise relative to the sur-
face of the creature. This organ is said to be the most rigid
and brittle of any in the animal, and is conjectured to con-
tain silicic acid. One docs well to note the section headings
of Sharp's description : "Organs of Locomotion," ^^ "Organs
of Food-taking," ^* "Organs of Defecation," ^^ "Organs of
Erection." ^^ An examination of figure 1 by the aid of let-
terings accompanying it, will give the reader some idea about
each of these sets of organs.

One of these organ systems must be attended to more
specifically. It is called by Sharp the neuroviotor appara-
tus (labelled in the figure m.m. and circ. oes. ring). The
discovery of this remarkable system may well be regarded
as epochal in the history of knowledge of the protozoa, for
it seems to indicate the presence of a nervous system in
the higher members of this great subdivision of the animal
kingdom no whit less well differentiated and elaborate than
in some of the metazoa and that by no means the lowest of
them. "This apparatus," says Sharp, "consists of a cen-
tral motor mass or motorium, from which definite strands
radiate: one to the roots of the dorsal membranelles (dorsal
motor strand) ; one to the roots of the adoral membranelles
(ventral motor strand) ; one to the circumoespohageal ring
(circumoesophageal ring strand) : and several pass out into
the ectoplasm of the operculum (opercular fibers). Each of
these strands may send off one or more branches. In the
walls of the oesophagus, both nervous and contractile fibers
may be distinguished." ^^

244 The Unity of the Organism

A True Nervous System Probably Present in Some Protozoa

Should further investigations confirm these discoveries, as
one may predict they will, nothing but purely speculative
considerations can restrain comparative anatomists from
putting the nervous system of the Diplodinium type along-
side that of some worms, so far as structural elaborateness
and functional effectiveness are concerned. Of course there
can be no possibility of homology between the two types,
if the term homology be used with the meaning generally at-
tached to it in comparative morphology.

If the possession by a protozoan of a nervous system
thus elaborate should be fully established, the fact would
have far-reaching consequences on our theories about these
animals. A few remarks are therefore in order as to the
probable general correctness of Sharp's observations. In
the first place, Mr. Sharp's statement, "Whatever there may
be of merit in the methods used and the results so far ob-
tained, is due to the kindly and helpful suggestions and in-
terest of Professor Kofoid, under whose direction the work
has been done," ^^ should be noticed. It mav be taken for
granted, I presume, that Professor Kofoid's wide knowledge
of the protista, and his long experience in the technique of
such research as that here involved constitute a weighty
guarantee for the trustworthiness of the results. The gen-
eral "internal evidence" of carefulness, for w^hich well-prac-
ticed biologists come to have so keen an eye, will, I think,
be recognized by all who read Mr. Sharp's memoir. From
the morphological side, the point most open to question is
that of the trustworthiness of the differential action of the
stains used. A modification of Mallory's connective tissue
stain seems to have been Sharp's main reliance, and it is
unfortunate that he does not inform us how this affects fib-
ers positively known to be nervous. Furthermore, it must
be remarked that the seeming identity of staining of this

Organums Consisting of One Cell 245

system and the micronucleus does not fall in very well with
accepted views touching tlie general character of these two
kinds of substance in the metazoa. But the general anatomy
of the system, and its relation to other organs undoubtedly
favor the behef tliat it is nervous. "All parts," says Sharp,
"connected with the neuromotor system act in perfect co-
ordination." ^^ And it should be said that this assertion
was based on attentive study of the living animals. "In
watching these phenomena of retraction and expansion in
the living, active animals one cannot help but be impressed
with the wonderful co-ordination of parts." -^

The idea that neural elements occur in the protozoa is,
as is well known, not new. The most definite report to this
effect previously made, is that by Neresheimer. This au-
thor describes fibers in Stentor running parallel with and in
general accompanying the myonemes. He believes these to
be nervous and calls them neurophanes. The observation
has not been confirmed so far as I am aware ; and one ob-
server, O. Schroder, believes that Neresheimer is in error
as to the existence of any such fibers in these animals. Nere-
sheimer's, and particularly Sharp's, reports will undoubted-
ly call forth renewed studies in this important field.

A More Critical Examination of the Term ''Organ*'

The parts of the protozoa occupied with determining the
creature's place in space are perhaps those to which the ap-
plication of the term organ is avoided with greatest diffi-
culty. "In the majority of Protozoa," says Calkins, "move-
ment is accomplished by the activity of special motor or-
gans, which may be either changeable processes (pseudopo-
dia) or permanent vibratile appendages (flagella and cil-
ia)." -^ This is a favorable place to remark on the justifia-
bility of calling pseudopodia (and other transitory cell
parts for that matter) organs. Science demands consist-

246 The Unity of the Orgamsm

ency. There are many transitory structures among multi-
cellular organisms notably connected with reproduction, for
example the liectocotylized arms of some cephalopods, which
we never hesitate to call organs. And taking the animal
kingdom as a whole, think of the innumerable organs occur-
ring in the embryonal and larval lives of animals ; for in-
stance the placenta in mammals and the gills of frogs in
the tadpole stage. No one hesitates to call these "organs"
because they are transient. As long as this is so, we can-
not consistently let the transitoriness of cell parts stand in
the way of calling them organs.

"The cilia and the stalk (of Vorticella) are definite, per-
manent organs, the first of the kind we have met with." ^^
One can justify the use of the term organ as applied to
the Protozoan by quoting indefinitely from practical writ-
ings by the best authorities. Yet when we come upon defini-
tions of "organ" framed to meet the needs of cellular ele-
mentalism, we find that the practice above referred to would
be illegitimate. Some of these definitions are wonderfully
naive. Take this from the H andworterhiich der Naturwis-
seTischaften,undcv the heading "Organs of the Animal Body."
"By organ we understand, in accordance with the original
sense of the word organori (Werkzeug, instrument) any
body-part, cither internal or external of a multicellular
living being, (Lebeuesen) such part being of regular form,
regular position, and definite, intimate, histological struc-
ture, and having to perform instrumentally a special func-
tion or operation in behalf of the living individual as a whole,
this whole being designated an organism because composed
of such organs," etc.

The naiveness here displayed lies in the recognition of
the term organ as going back in use and meaning to the
ancient Greeks, and in the same breath restricting its ap-
plication to multicellular organisms. When Aristotle recog-
nized that "each sense is confined to a single order of sensi-

Orgmmms Consisting of One Cell 247

bles, and its organ must be such as to admit the action of
that kind or order," and went on to point out that the
organs must be "heterogeneous," (that is, as later anatomy
came to say, composed of tissues); and when William Har-
vey spoke of the heart as an organ and described its shape,
structure, blood capacity, density and movements, and the
passage of the blood through it, beyond a shadow of doubt
these men had a perfectly clear conception of the most es-
sential attributes of an organ, though of course they knew
notliing about cells. And does any one believe that had
they seen the locomotor parts, let us say, or the mouth of
Diplodinium, they would have hesitated, though still wholly
ignorant of cells, to call these parts organs, doing so on
the same basis on which they had called the sensory parts
and the heart of larger animals organs? Can any one
either fail to see the point or refuse to admit the validity
of the argument?

The term organ stands for certain kinds of natural ob-
jects. First and foremost these objects are definite parts
of an organism ; definite that is, in that they have a certain
form and character of their own, perform definite offices in
the economy of the organism as a totality, and are in turn
composed of definite elements. Thus understood the term
has had a place in the science of living beings for centuries,
as we have just seen. How now, has the advance of knowl-
edge affected the earlier understanding of the nature of or-
gans? Undoubtedly it has expanded that understanding
in a number of directions ; it has made it fuller. One of the
directions of enlargement pertains to the composition of the
organs. It is found that for a large part of the organic
world, namely the Tw^Z^icellular animals and plants, the ele-
ments of the organs are tissues, all of which are derived from
still another kind of elements, namely cells.

The discovery of cells has greatly enriched and clarified
the definition of the terai organ ; but there is no shadow of

S48 llie Unity of the Organism

right in the view that the discovery has at the same time
narrowed the application of the term. As the preceding
discussion shows, historically, logically, and biologically,
the mouth or the locomotor appendages of a protozoan have
exactly the same right to be called organs as have the same
parts of a metazoan. The dodging in this matter, as seen
for example in the proposal to keep the organs of the pro-
tozoa quite apart from those of the metazoa, by calling
them "organelles," "organoids," "cyto-" one-thing-and-
another, is indefensible so far as animals themselves are
concerned. And no one should wish to minimize the import-
ance of the point at issue by imagining the question to be
merely one of terminology — of what the objects dealt with
shall be named. That this is by no means all there is to it
may be discovered by noticing the warmth with which a
genuine cellular elementalist will come to the defence of his
terminology when its legitimacy is seriously questioned. The
truth is, and let us not miss it, behind this "mere matter of
terms" there is in hiding the scientifically reprehensible
practice of trying to disguise or obscure facts in the interest
of a theory. And the practice entails, as the defence of
false theories always entails, contradictions and obscura-
tions of all sorts. To illustrate, it is said by cellologists
that a protozoan's mouth must not be called a mouth but a
cytostome because being in a cell and not composed of cells
it is only analogous, but not homologous with the metazoan
or "true" mouth. From which it follows by clear inference
that all metazoan mouths are homologous, those of a lobster
and of a dog, for example ! But the anatomical absurdity
of the situation is easily met by those who are committed
to the defence of the theory regardless of facts, by simply
pointing out that the mouths of a lobster and a dog are
homologous just because they are both multicellular. If
one wishes to prove that no wooden building is a true liouse,
he can do this to his satisfaction, if his mind works that

Organisms Consisting of One Cell 249

way, by defining house as a building which must be com-
posed of brick or of stone.

More Detailed Examination of the Anatomy of Higher

Protozoa

m

In behalf of the treatment of reproduction and heredity
which will engage us later on, we must now extend our ac-
quaintance with the finer structure of some of the more
highly developed jn-otozoa. Stylonychia^ about which some-
thing has already been said, may be the first object of
closer scrutiny. Putter, who has given special attention
to the activities of many protista, remarks, "One may take
a hypotrichous infusorian {Stylonychia being typical) as an
example of the highest complication of body-fonn which a
single cell is able to reach, for in addition to differentiation
into dorsal and ventral sides and the very complicated form
of the periphery, we find no less than six different groups of
ciHa." 23

Putter's ' representation of a side view^ of Stylonychia
mytilus, copied in various books and shown in figure 5, illus-
trates his statement. He describes in detail the movements
of the cilia in crawling; and from all this and from what
others have written on the subject, it is entirely permissible
to call these main cilia limbs or legs. The elaborate system
of fibers connecting and coordinating these limbs will be
spoken of in a later section. The statement by Putter about
the extent of complication of body possible in a single cell
prompts one to wonder, in view of the elaborateness of these
animals, whether the limits of possibility of structural dif-
ferentiation is much narrower for single-celled than for
many-celled animals. In none of the metazoa, excepting the
arthropoda and higher vertebrata, do we find a more highly
differentiated, and, seemingly, integrated system of loco-
motor organs than in Stylonychia and its congeners.

250

The Unity of the Organifim

Figure 6 shows numerous details of the system of external
organs of Stylonijchia histrio. The figure was made from a
section of the peristomal field. Special attention is called to
the finely striated appearance of the membranellaCj m I, and the

M±>p,

Eri

^j

FIGURE 6. STYLONYCHIA HISTRIO ( AFTER 3IAIER).

Mbp., preoral membrane. Sc, frontal cirrhi. Bs., basal strand.
Bs-S basal strand of membranellae. J., endoplasmic inclusions. Bf.,
l)asal fibers, p., pellicula. En., endoplasm.

pre-oral membrane, m hp, these striae being evidence that the
organs are produced by a fusion of cilia. The distinction be-
tween the basal lamella, hi, and the basal granules should also
be noticed. The investigation from which this figure is taken
is particularly instructive because it is based on a large num-
ber of representative genera and because the discussion brings

Organisms Consisting) of One Cell

251

out various inferences concerning certain important aspects of
development^ even though the observations were mostly limited
to the completed organs. To these latter we shall return
the chapter on development and heredity. *

m

FIOTTRK 7. CniTlTTniA LEPTOCORIDIS (aFTER McCULLOCh).

ax., nxostyle. bas.gr., basal gramile. chr.gr., chromatin granule.
f1., flageJluni. n., nucleus, rh., rblzoplast. und.ni., undulating mem-
brane, vac, vacuole-like area about the "kiuetonucleus." kn., kine-
tonucleus.

So far our glance at the complication of structure occur-
ring among the protozoa has been directed chiefly to the
organs of contact with the outside world. These organs are
particularly characteristic of the large species, and in gen-
eral of those leading the freest, most active lives. From the
relative conspicuousness of these organs and the ease with

25S The Unity of the Organism

which they can be observed it has naturally come about
that they have been studied most and are the most accu-
rately known of all the organs of these small animals. But
extensive researches in recent years have brought to light
a whole system of organs in one group of protozoans, the
flagellata, that was entirely unknown a generation ago. The
subdivision of the flagellata referred to contains the try-
panosomes, animals which have come into prominence lately
because many of them are parasitic in man and beast, pro-

-Tf-UC.

FIGURE 8. CRITHIDIA LEPTOCORIDIS ( AFTER McCULLOCh).

a.f., axial filament, bas.gr., basal granule, c, centrosome. rh.,
rhizoplast. nuc, nucleus.

ducing a long list of diseases of which sleeping sickness is
probably the most generally known. As we are now more
interested in the organisms than in the effects they have upon
their hosts, other species akin to the trypanosomes, but un-
known except among specialists, will best sei*ve our purpose.
The examples I select are shown in figures 7 and 8. The
species illustrated by figure 7 is Crithidia leptocoridis
McCulloch.* This species has been chosen for the purpose
of showing the newly discovered system of organs mentioned
above, so structural details other tlian those of the system
are not shown in the drawing.

* This occurs in various parts of the United States. The descrip-
tion of the creature is by Miss Irene McCulloch (An Outline of the
Morphology and Life History of Crithidia lepiororidis, n. sp. Univ. of
Calif. Pul)l. /ool., \'ol. Hi, pp. 1-22, 191.5), one of the group of students
in protozoology working under the guidance of Professor Kofoid,

Organisms Consisting of One Cell 253

The flagclliim marks the anterior end of the creature; and along
with it there is an undulating membrane, the two forming an
efficient locomotor apparatus.

The explanations accompanying figures 7 and 8 name the parts
of the system. Special attention may be called to the following
points :

The nucleus, u, with its distinct membrane, central karyosoine,
and clear space between the latter and the membrane; the
hinetonucleus (always written with quotation marks by Miss Mc-
Culloch, for reasons which we shall mention later) ; the rhizo-
plast, a fine thread connecting the karyosome of the nucleus with
the kinetonucleus; the ha^al granule with its numerous very fine
connections running to the kinetonucleus ; and the a.rostyle, a
thread extending from the basal granule to the posterior end
of the body.

Concerning the function of all these parts our knowledge is
very fragmentary. The reader should never forget the diffi-
culty of observing these organisms. The largest individuals of
this species are 40 or about 1/625 of an inch long, and as
the figure shows, narrow in proportion to the length. Because
of this minuteness several of the parts, for example the rhizo-
plast and the various granules, are at the very limit of visibility
by the best microscopes. This fact, combined with the peculiar
conditions under which the animals live, make it impossible to
study a single individual during its whole life or even a con-
siderable portion of it. Probably the impossibility of studying
the parts as they do their work is chiefly responsible for the
meagerness of w^hat we know about the functions of the organs.
The nucleus of a large number of protozoans, including this one,
is often called a trophonucleus from the theory that it is chiefly
concerned with nutrition.

The term kinetonucleus has been a])plied to the organ thus
labelled from the conjecture that it has specially to do with
the movements of the animal. As the figure shows, the flagellum
is connected, though indirectly, with this organ, and this means
that the undulating membrane is also related to it. But the
fact that there are plenty of flagella and undulating membranes
in other species which have no kinetonucleus, makes it certain
that its role in the production of motion can not be exclusive
or very fundamental. Concerning the office of the several gra-
nules, the rhizoplast and the axostyle, nothing positive seenas

254 The Unity of the Organism

to be known. When, consequently, the wliole complex is spoken
of as a "system of organs/' we must keep in mind the fact
that we are certain of its being a single system only in a
morphological sense. The mere fact that several organs are
structurally connected with one another does not by any means
signify that they are all concerned in a single operation. For
example, such complexes as muscle-nerve and gland-nerve-duct
are morphological systems which perform several quite distinct
functions.

A matter of much theoretical interest is involved in the appli-
cation of the terms chromatic and chromatin to several of the
parts of the system. The karyosome of the nucleus is called
chromatin, as are the kinetonucleus, the basal granule, and the
granule in the axostyle near the posterior end of the body. And
the axostyle itself is said by Miss McCulloch to be "present ap-
parently in the form of a chromatic thread." The flagellum and
nuclear membrane are not held to be chromatic, even though
they seem to take stains quite as well as the other parts which
are called chromatin primarily because they are thus acted on.
Mention may be made too, of the fact that some of the parts,
notably the karyosome. w^hich are considered to be chromatin,
are shown by IVIiss McCulloch to stain with unequal intensity
at different times. The subject of chromatin and chromatic
bodies, has played a prodigious part in recent theoretical biology,
especially in speculations about heredity. We shall consequently
be obliged to give more attention to it in the discussion of how
organisms reproduce themselves. What has been described is
only the adult stage, or as it is often called, the vegetative stage
in the creature's life cycle, this being sufficient for our present
aims. Considerable is known about several other stages of
this and related species ; but our purpose now is only to get in
mind as clear a picture as possible of the make-up of the
animal in the culminating stage of its life.

The other species selected to illustrate this new system of
internal protozoan organs shown in figure 9 is Giardia
muris, the specific name referring to the fact that the creature
is an inhabitant of mice. The figure and description are by
Kofoid and Christiansen. The facts to which special attention
is invited in this animal are the way in which all the various
granules and bodies are connected with one another by fibers,
the almost perfect bilateral symmetry of the animals, and
particularly the presence of two nuclei, nuc- The binuclear con-

Organisms Consisting of One Cell

255

ditioii oi' tliis protist is not merely a stage in the life history of
the organism. No uni-niicleate stage occurs and the creatnre is
typically organized on tlie binucleate plan. It should be noted
that the two nuclei are alike mor))liologically and ])resumably
physiologically, so they do not correspond to the macro- and
micro-nuclei of some ciliates. The animal may consequently be

anfchlosmu.

i-nffocut.la+.fl-

^ cyt.- - -

XTUCt -

cary.halox- -

cartjr - -

post perisjK - -

por.if-- -

tri.halo.-- - -

ax

pos

lb

as.

anLVialo

- -anf. per-is^
l.blfepH.

cen-t.

tn'tf QTtuc. rhir

lat. bQs.g-r.

--ant. Iat.f1.
--r£ir. vent.f 1.

post. lat. f 1.
tjost. t1.

FIGURE 9. GIARDIA MURIS (aFTER KOFOID AXI) ClIRISTI AXSE X ) .

ant. chiasma, anterior chiasnia. ant.halo., anterior halo, ant.lat.fl.,
anterior lateral flagellum. ant.perist., anterior peristome, ax., axo-
style. cary., karyosome. cary.halo, karyosonial halo, cent., centre-
some, cyt., cytostome. fr.vent.fl., free ventral flagellum. intraeyt.-
lat.fl., intracytoplasmie part of the postero-lateral flagellum. intra-
nuc.rhiz., intranuclear rhizoplast. lat.bas.gr., lateral l)asal granule,
post.fl., posterior flagellum. post.lat.fl., posterior lateral flagellum.
post.perist., posterior peristome, l.bleph., left blepharoplast. rhiz.,
rhizoplast. tri.halo., triangular halo.

justly regarded, as Kofoid and Christiansen remark, as the
"simplest (from the standpoint of numbers only) possible multi-
nuclear organisms." ^* Special notice should also be taken of the
hlepharoplasts (1. bleph.), the axostyle (ax.) and the parabasal
bodies (par. b.)

Worthy of mention is the fact that this system of organs,
called by the authors the neuromotor system, is so well differen-
tiated from the rest of the body sub^tanpe, and so pernianent

256 The Unity of the Organism

that it may remain intact after the softer, more plastic parts
of the body have undergone dissolution. It reminds one of a
skeleton quite as much as of any other system belonging to the
higher animals, though this remark is not intended as a sug-
gestion that it may be of this nature. But the fact of capital
importance to the present discussion is the remarkable degree
of structural unification, or in accordance with the terminology
favored by us, the structural integratedness of the animal through
this organ system. All analogy warrants the supposition that
functional integration of some sort corresponds to this structural
integration, and if ever research discovers what that function
is (or those functions are, for the possibility that there may
be several should never be lost sight of), the insight thus
obtained into the nature of these creatures would be another
long step toward banishing the doctrine of the simplicity of
the protozoa.

The Fiction of Structureless Organisms

Having informed ourselves concerning the highest grades
of organization known among unicellular beings we must
inquire about the lowest grades. The immediate question is,
are genuinely structureless or homogeneous or amorphous
living beings known .^ The next and far more searching
question is, if such beings are not known (and they surely
are not) does the nature of the inductive evidence demand
or even warrant the supposition that tliey must exist some-
where or must have existed at some time although we can
get no evidence to this effect.'^

The supposed existence of beings of this sort has cut a
large figure in speculative biology. One need only refer to
the moneron theory of Haeckel and its wonderful vitality
shown by its cropping out everywhere, even in elementary
and popular writings, and by its receiving a show of assent
simultaneously with the admission that actual observation
tends to disprove the theory. A good example of the per-
sistence of the teaching is shown by Haeckel's The Evolution
of Man. In the fifth edition, English, 1903, we read, "The

Organisms Consisting of One Cell 257

earliest unicellular organisms can only have been evolved
from the simplest organisms we know, the monera. These
are the simplest living things that we can conceive. Their
whole body is nothing but a particle of plasm, a granule of
living albuminous matter." -'' So far as the protozoa are
concerned, no zoologist who is both well infonned and in-
tellectually free and candid pretends any longer that such
beings are known. "In all ])rotozoa that have been exam-
ined in recent times, at least one nucleus has been found
to occur without exception." ^^ It hardly needs to be re-
marked that even the possession of a nucleus is sufficient to
take an organism out of the category "organisms without
organs." But as a matter of fact the nucleus is not the
only differentiated part that has been demonstrated in the
simplest protozoa.

The Structure of Bacteria

The visible living beings to which the term structure-
lessness can be ascribed with the greatest plausibility are
the heterogeneous myriads known as the bacteria. Whether
or not these organisms are time cells, that is, are "nucleated
masses of protoplasm," has been extensively debated in re-
cent years. This much may be regarded as settled: If by
nucleus one is to understand a cell organ of such structure
as that which is characteristic of ordinary plants and ani-
mals, then the bacteria are not nucleated. But this is far
from meaning that the organisms are structureless.

{a) Membrane and Surface Structures

In the first place, there seems to be almost complete agree-
ment among authorities that in bacteria the body is differ-
entiated into at least one outer coat or membrane and an
inner mass. It should be specially noted that the membrane
is by no means a mere passive, wholly extrinsic thing, like

9

258 The Unity of the Organism

the cover to a base-ball. It is an essential, active, living
part of the organism. It seems to correspond more to the
skin of a higher animal than to a man's coat, or to the
shell of a mollusc or of a walnut. "Unlike the cell-wall of
the higher plants, it [the outer layer of the bacterium] gives
usually no reactions of cellulose, nor is chitin present as in
the fungi, but it consists of a proteid substance and is ap-
parently a modification of the general protoplasm." -^ This
appears to express the most common view, especially among
bacteriologists proper. Some authorities, as Kolle and
Wassermann, speak of the ectoplasm and endoplasm, and
declare that a "cell-membrane, such as is present in plant
cells, is not to be thought of" -^ in the bacteria. If the
membrane is comparable with that of the cells of any multi-
cellular organisms at all, it would seem to be more akin to
that of the animal cell than the plant cell, for nearly all
authorities consulted agree that only in exceptional cases
does cellulose occur in it, and W. Beneke says that the re-
peated assertion of the presence of cellulose in many bacteria
is unproved. Even the presence of chitin, still more fre-
quently affirmed by writers, is doubted by this author, and
he tells us "we know nothing concerning the chemical struc-
ture of the Avail." -^ Arthur Meyer takes vigorous ground
against the views above indicated as to the nature of the
bacterial membrane. He believes these organisms are more
closely related to the fungi than to any other group and
that through these their kinship to higher plants is estab-
lished. But even he admits that "It is very easy to recog-
nize that the bacteria possess a cell-membrane morpholog-
ically similar to the membrane of fungi, even to that of
higher plants." -^ And he thinks that perhaps there is more
similarity between the epidermis of aquatic higher plants
and the bacterial wall than between the latter and the cell
wall of higher plants.

Aside from the question of the chemical composition of

Organisms Consisting of One Cell 259

the bacterial membrane, two facts seem to indicate its active
charax'ter: the presence in many species of a mucous en-
velope, presumably secreted by the membrane, and the pres-
ence in many others of cilia which in some cases are almost
certainly outgrowths of the membrane. It seems to have
been proved that in Spirilluni gigantcani, the ciliary tuft
with which each end of the body is armed arises from the
inner body mass and passes through a chink in the mem-
brane. Meyer and a few other authorities consulted are of
the opinion that this is the typical mode of origin. But too
many capable observers are positive about their having
demonstrated the origin of the cilia from the membrane
in widely separated species to permit us to believe that
this is not in fact the mode of origin in many species. Thus
V. A. Moore : "The flagella appear as hair-like appendages
or filaments, which radiate from the bacteria. They are
given off from the cell wall of the germs of which they
appear to be continuations or projections." ^^

So meager is our knowledge of the individual activities
of these minute beings that the simplest trustworthy obser-
vations in this field are welcome, and the following from
^loore's paper is worth quoting even though its bearing on
the membrane question is only indirect. Speaking of the
behavior of the organisms when the cilia of several indi-
viduals become entangled with one another the author says
they exhibit "a trembling motion, then a jerking, reeling
and pitching movement, until finally they are free and
move across the field," and "it seems highly probable that
detachment or breaking of the appendages is produced dur-
ing these voluntary movements, b^^ their contact and pos-
sible entanglement with each other." ^^

The probable active participation of the membrane in
the division of the bacterium is evidence from another di-
rection that the structure is a real part of the organization
of the being.

260 The Unity of the Organism

(b) Structure of the Inner Portion

*

Wc now pass from the consideration of the peripheral
parts of the bacteria to an examination of the internal body
mass. Recent discussion of this subject having been mostly
carried on from the elementalist standpoint, with either nu-
cleus or chromatin as the guiding star, gives the distinct
impression of having for its end not full and accurate de-
scription of anything and everything that exists in the
organism, but proof that a nucleus or chromatin either do
or do not occur there. Writings under this head are so
numerous and voluminous as to make a comprehensive re-
view out of the question, and the diversity of opinion is so
great and so strenuously set forth in some instances as to
make satisfactory judgment of just what has been found
difficult. The one thing that stands out with great clear-
ness in the illustrations and descriptions of such recent
works as those of Biitschli, Schaudinn, Arthur Meyer, Guil-
lermond, Menol, Ruzicka, Swellengrebel, and Dobell, is that
the main body substance of the organisms is far from homo-
geneous. A considerable variety of objects are undoubtedly
differentiated within the protoplasm. Difference of opinion
among the latest investigators concerns only the nature of
these objects. Perhaps the most generally observed differ-
entiations are granules of various sizes, shapes and behavior
toward stains. The next most common structures seem to
be networks and strands of varied character. The mate-
rials of these appear to differ generally from those of the
granules in "taking" stains with less avidity. Vacuoles are
another type of structure which present-day methods are
discovering to play an important part in these minute or-
ganisms, as they have long been known to do in many pro-
tozoa, and in the cells of higher plants.

The narrower needs of our undertaking do not require us
to examine farther these internal parts. The bare fact of

Organisms Consisting of One Cell 261

their existence is conclusive proof that the main body of the
organisms is not structureless ; and almost conclusive proof
too, when the extreme minuteness, and hence difficulty of
observation is taken into account, that not only are they
not structureless, but that their structure would amount,
could it be seen as readily as that of larger organisms, to a
very considerable degree of complexity of organization.
And this, be it noticed, follows even though considerable
portions of the body substance, especially in some stages of
the individual life cycle, still look structureless or homo-
geneous mider the highest magnifications and best conditions
of lighting and staining. Although this phase of our dis-
cussion does not require us to go farther into the inter-
pretation of the structure thus generally looked at, it is
nevertheless desirable to attend to the subject a little more
specifically.

{c) The Question of a Nucleus in Bacteria

We may first speak of the present status of the nuclear
problem as touching the bacteria. The most prevalent view
still is that the bacterium is a non-nucleated cell, if by
nucleus one is to understand the organ that goes by that
name in higher plants and animals. But there is plenty of
dissent from this view, and seemingly this is growing in
volume. Those who believe in the presence of a nucleus are
still far from agreement as to what shall be regarded as this
organ. One group of observers speak of a "diffuse nucleus,"
the idea being that certain of the granules mentioned above
are chromatin or something close of kin thereto ; and since
according to a widely prevalent theory, this is the most es-
sential constituent of the nucleus in the cells of higher or-
ganisms, they believe it justifiable to consider bacteria nu-
cleated. Schaudinn and Richard Hertwig are prominent
advocates of this view, the former basing it primarily on his

262 , The Unity of the Organisin

studies of Bacillus hiltschlii, and the latter making use of
the bacteria as one illustration of his now well-known chro-
niidial network theory.

Another view, proposed by Biitschli in 1890 and since
favored by several students, is that the whole bod}'^ of the
bacterium is equivalent to the nucleus of a typical cell. A
recent strong advocate of this view is Vladislav Ruzicka.
This author defends the theorj^ mainly on the evidence he
believes he has obtained that bacteria as well as mammalian
red blood corpuscles, familiar examples of non-nucleated
cells, resist digestion in gastric juice in the same way as do
the nuclei of t3'pical cells.

Still another group of authors believe nuclei not funda-
mentally different from typical nuclei are present in bac-
teria. But again as soon as this view is examined in detail,
the widest possible differences are found as to the criterion
of what a nucleus is, and as to what objects in the organism
are nuclei. Arthur Meyer, one of the most conservative
supporters of this general view, believes he is able to demon-
strate a nucleus in several genera and species, in the form
of a minute granule more highly light-refracting than the
surrounding cytoplasm as seen in the unstained condition,
and reacting differently from all other substances toward
various stains. It is most readily seen in the spore stage
of the organism's life, and has so far been demgnstrated in
only a comparatively few species, taking the bacterial group
as a whole. Dobell on the other hand, believes himself justi-
fied, after an examination of many species belonging to
nearly the whole bacterial series, in declaring, "I think I
may fairly claim from what has been pointed out in the
preceding pages that not only do my own observations fur-
nish conclusive evidence with regard to the nucleus in bac-
teria, but that in almost every case in which careful investi-
gation has been made by others, the results are not
inconsistent with mine," his results being that "tlie Bacteria

Orgnni.sms Consisting of One Cell 263

are, like the Protista generally, nucleated organisms." •'^-
But the most cursory examination of Dobell's figures makes
it obvious tliat what he regards as the nucleus is not what
Meyer believes to be this organ, excepting possibly in the
coccus forms. Dobell's nucleus is, in most of the elongated
species, an axially elongated, usually extremely irregular,
more or less fragmentary affair, varying greatly for differ-
ent stages and conditions of the organisms. These two
investigators are severe in their criticism of each other's
work and conclusions.

Various other structures are described and figured, and
various interpretations given, of the supposed nucleus of
the bacteria, but we need go no further at present with the
examination. Our main contention may be regarded as
established: structurally viewed there is no longer any room
for doubt that the bacteria are organisms in the usual sense
of that term, that is, in the sense of possessing parts de-
voted to particular activities ; but that there is unlimited
room for doubt how, if at all, the conception "cell" as a
nucleated mass of protoplasm is to be applied to these or-
ganisms. Structurally viewed, I say, the case stands this
way. But if we approach the bacteria from the chemico-
physiological side, the case against the cellular and for the
organismal conception is still stronger.

Bacteria Undoubted Organisms Whether ''True Cells''

or Not.

It has been often remarked that Bacteriology is pre-
eminently the department of biology that relies on functional
rather than on structural attributes for its determinations.
This character of the science results from the extreme
minuteness of the creatures which renders morphological
study of them so difficult. One of the most striking, indeed
one of the most remarkable facts about "microbes" is that

264 The Unity of the Organism

they are so like ordinary living things in their general modes
of life despite their excessive minuteness, and, as judged by
ordinary anatomical standards, despite their structural
simplicity. Like other organisms they feed and respire and
propagate their kind ; and they sui-idve in an active condition
only within a range of temperatures not greatly different
from that which conditions the lives of other beings. But
striking as is their similarity to organisms generally in
these attributes-in-common, still more striking is their
specific diversity among themselves. That organisms so
small as to be barely visible, or even invisible to the highest
powers of the microscope, should still be subject to the gen-
eral principles of specific differentiation in habits of life
and hereditary transmission as are the largest, most com-
plex organisms, seems to me one of the marvels of the living
world.

In this field as in so many others, the facts which touch
human welfare the most vitally are best known. Take the
case of smallpox and chickenpox. These are both diseases
of the human skin and are so much alike as to be often con-
fused even by physicians not especially experienced in this
field ; yet to the expert the difference between them is de-
clared to be positive and unmistakable. "Smallpox has
rather severe prodromes, backache, head-ache, fever, and
sorethroat, the rash appearing on the third and fourth day.
Chickenpox usually has light or no prodromes, the rash ap-
pearing on the same day or within twenty-four hours as a
rule. In both diseases the face, chest, back, arms, hands,
legs, and feet are likely to show eruptions, but chickenpox
tends to show the greatest number of spots 'under cover,'
i.e., on the parts usually covered b}^ clothing, while smallpox
tends to show the majority on the face, neck, arms, wrists,
and hands, rather than on the body. Tlie skin lesions them-
selves differ very markedly, the typical lesions of chickenpox
being superficial, thin-walled, high, rounded, and filled with

Organisms Coiisisting of One Cell 265

clear liquid ; those of small pox being deep-seated, tense,
opaque, covered with a tougli skin. There are many other
points of distinction, and any one familiar with the two
diseases can hardly fall into error when dealing with typical
cases at whatever stage they are encountered." ^^

This is the type of discriminative description that occurs
everywhere in the writings of biological taxonomists. It is
as characteristic of zoological and botanical, as it is of
medical "diagnoses." Yet the organic species themselves
implicated in the diseases are invisible under the highest
magnifications so far produced, the specific discriminations
being based exclusively on the effects arising from the dif-
ferent activities of the two kinds of organisms ! Now what
are the probabilities as to the structural attributes of these
invisible beings? Answering in the light of what is well
known about all familiar organisms, can we say anything
else than that the microbes of smallpox and chickenpox, not
only possess differentiated and coordinated parts, that is,
are organized, but that the two species are to some extent
differently organized? Nor is the evidence of specificity in
this case at all exceptional for ultra-minute organisms, as
every one knows who has given attention to the popular
subject of "germ-life." Some of the disease producers, as
those of rabies, it is true, are able to flourish in a consider-
able range of hosts ; but this is also the case with many pro-
tozoan and even metazoan parasites. The microbe of hog
cholera is, according to present knowledge, as closely re-
stricted as to possible hosts as that of any disease pro-
ducer w^hatever; and judging from its ability to pass
throucfh filters, it is one of tlie smallest of the ultra-micro-
scopic species. So on the whole it appears that the prin-
ciples of host adaptability are essentially the same through-
out the whole range of parasitic life regardless of size.

But while this statement about the conformity of bacteria
to the general rules of species differentiation and constancy

^66 The Unity of the Organism

is undoubtedly true as a general proposition, at the same
time the group presents a degree of structural and func-
tional plasticity which surpasses, probably, anything oc-
curring in any other group. Under the term "pleomor-
phism" this multiform character of bacteria has been the
subject of much investigation and no little heated discussion.
One party, headed by the German botanist Nageli, has main-
tained that the organisms are not classifiable in the usual
sense of biological taxonom}- at all — that any form is suc-
ceptible of becoming almost any other form, depending on
the external conditions under which it is placed. The other
party, of whom Cohn seems to have been the originator, has
stoutly insisted that species and genera are as definite in
bacteria as in any other group, and that every infectious
disease has its specific germ agent. The evidence and the
controversy need not be followed into details. The truth
undoubtedly lies somewhere between these extreme views.
"Bacterial species exist, but they are all of the kind called
in the language of the science of classification un-
defined:''^"^

The great body of facts instanced in the foregoing pages
furnish the answer to the question raised early in this sec-
tion, namely, does the inductive evidence warrant the sup-
position that homogeneous or structureless or organless
organisms actually exist .^ No, appears to be the only reply
permissible, and this in spite of the fact that the observable
organic world taken as a whole does undoubtedly show a
general simplification with diminution in size.

If we feel compelled to speculate, but yet resolve, as we
must when fullv committed to the inductive method, to hold
speculation to strict accountability to observational evi-
dence, then are we driven to the conclusion tliat simplifica-
tion of structure and diminution in size of organisms go
hand in hand, but that neither ever reaches the vanisliing
point, even thougli we know nothing aliout the limit of

Organisms Consisting of One Cell S67

possibility as to size or as to simplicity of structure. This
examination of the protista brings into clear light a diffi-
culty not otherwise recognizable in the way of applying the
cell-theory to this section of the living world. The con-
cept cell being })rimarily one of structure and only second-
arily one of function, necessarily becomes inapplicable to
invisible beings so far as special objectivity is concerned,
while the concept organism being primarily one of function
and only secondarily one of structure, is quite as applicable
to invisible as to visible beings if, as in the case of disease-
producing microbes, we have observational evidence on the
functional side of their nature. No discoveries in the whole
biological realm have more clearly revealed the fatuousness
of the claim made by the cell-theory to being the "key
to all biological problems," than have those establishing
the existence of barely visible and invisible living things.
On the other hand, these discoveries taken along with those
concerning the structure of the protozoa and visible bac-
teria, have contributed greatly to the expansion and clar-
ification of the organismal conception.

B. DEVEI.OPMENT

False Concejjfions About Development in Protozoa

We have now seen something of the disastrous effects of
trying to squeeze the whole adult structure of the pro-
tozoan into the theoretically "simple cell." It remains to
look at the still worse effects of trying to keep the facts
of development of the individual protozoan down to the
same theoretical limitations. We will first examine the no-
tion constantly inculcated by text-books and in formal in-
struction, that there is "no true developm.ent" in these crea-
tures. Embryology is almost always defined and treated so as
to exclude from Its scope development in the protozoa. Thus

S68 The Unity of the Organiftm

the preface to the monumental Treatise on Comparative
Embryology by F. M. Balfour contains this: ". . . the
work is, I believe, with the exception of a small but useful
volume by Packard, the first attempt to deal in a complete
manner with the whole science of Embryology in its recent
aspects. . . ." ^^ But the introduction tells us specifically
that the actual scope of the work is not to be thus ambi-
tious after alL "The present treatise deals only with the
Embryology of Animals, and is further confined to those
animals known as Metazoa." ^^ It will be noted that noth-
ing in this statement compels the inference that Balfour con-
ceived Embryology as being actually limited to the metazoa.
In fact, if anything, the opposite might be inferred. Con-
siderable reference is made to protozoan reproduction in the
Introduction, which however has to do only with conjuga-
tion and spore formation and the problem of the origin
of the metazoa from the protozoa and especially the origin
of sexual reproduction. But the theory of the "formation
of the individual from the structureless germ'' (italics
mine),^^ and of the individual metazoan as "equivalent to
a number of Protozoa coalesced to form a single organism
in a higher state of aggregation," '^'^ advnnbrates the fal-
lacious doctrines about the relation of the organism's cells
to the organism which have come to dominate biological
theory, and against which we are taking strong ground.

"Inasmuch as the individual Protozoan has the morpho-
logical value of a single cell, the embryology of the Protozoa
belongs to the province of cell morphology. For this reason
it is usually excluded from the domain of comparative em-
bryology of animals in the stricter sense; in this book too, it
will receive no consideration. Comparative embryology has
to do accordingly with the development of the Metazoa." ^'*
It is satisfactory to note that in the later general part of
the great text-book from which this paragraph is quoted,
the authors have given a much more adequate defini-

Organisms Consisting of One Cell 269

tion of development (Entzmckhing) and embryology {Ent-
wicklungsgeschiclite) . "By development," they say, "we
understand the course of those form-changes through wliich
organic figure is produced." *'* And "embryology is a
descriptive presentation of the developmental processes of
the organism." ^^ But development of the protozoa is as
rigidly excluded from all the discussions in this newer general
part as it was from the older special part.

"The science of embryology," we read, "has for its sub-
ject-matter the growth of animals from the time when they
first appear as germs in the bodies of their parents until
they reach the adult condition and are able to produce simi-
lar germs themselves." ^- Though this statement seems
broad enough to cover the development of many, at least,
of the protozoa, yet when one turns to the body of the work
to see how these animals have fared, he is quite taken aback
to find that they simply are not mentioned at all. So the
inference seems unescapable that according to the views of
the embryologists responsible for the above statement, in
this great section of the animal w^orld there are no such
things as germs contained in the bodies of parents, which
grow to reach the adult condition. According to their
viexcs, I say, because not for a moment is it to be supposed
they are unaware of the fact that one of the primary
subdivisions of the protozoa, the sporozoa, receive their
name from the almost universality among them of repro-
duction through sporulation, the spores or germs being
in most cases formed within the encysted parent animal.
And the authors are, of course, familiar with the conjuga-
tion of male and female gametes in many species to produce
the zygote, the parent of the spores, from which in turn the
adult animals are developed.

Although it is unfortunately true that there is dearth
of observational knowledge on the growth of the adult from
the spores, yet the dozen and more developmental stages

270

Tlie Unittj of the Organism

of the sixteen-millimctcr-long Porospora gigantea described
by E. van Beneden and discussed and figured by Biitschli
shows us an ontogeny or individual development in one case
no less positive, and probably little less complex were all

cp'm.

r TU*

n.

cl.m.

FIGURE 10. CORYCELLA ARMATA (fROM WASIELEWSKI, AFTER LEGER).

ep'm., epimerite. pr'iii., protomeritc. d.m., deutomerite. n., nucleus.

the details known, than that of many endoparasitic worms.*

But how could a zoologist hesitate to recognize that so

elaborate an organism, as for example a Cort/ceUa, figure

* With reference to tlie develoj)ment of tliis species, it should he
remarked that althou<»h hiter researches have proved that the amoohoid
stages considered hy van Beneden to belong to this series in reality have
nothing to do witli this animal, yet the later stages leading up to the
(inal one, or "trophozoite" seem not to have been questioned; and these
constitute the evidence af an oiitoyeny with which we are now specially
concerned.

Organisms Consisting of One Cell 271

10, the body of whicli is sharply difFerentiated into the three
distinct parts called the deutomerite, protomerite and epi-
merite,^'^ (the latter being a fixation organ of greatly varied
form in different species, and often highly specialized), must
imply an ontogeny of no mean extent? Nor are we any
longer without knowledge, at least in outline, of the develop-
mental series in this part of the sporozoan cycle for several
other series. The investigations of Leger and Dubosq are
especially noteworthy in this connection. From their ac-
count of the development of Pyxinia mobuszi we learn that
in this species the full grown animal, the slender epimerite
not included, is five times the length of the sporozoite ; and
the epimerite attaining a length greater than that of the
rest of the animal, penetrates through the entire length of
the epithelial cell of the intestine of the host. The whole
of the adult animal except the epimerite projects free into
the intestinal cavity.

Misuse of the Term "Ontogeny/'"

I give only one other quotation showing the extent to
which this obscuration of the facts of protozoan develop-
ment has gone in the interests of cellular elementalism. This
quotation is specially telling because it is genuinely up to
date and displays the extremity of the tendency by not be-
ing restricted to the meaning of the term embryogeny, con-
cerning the scope of which there is good historical and bio-
logical ground for difference of opinion, but goes to the
term ontogeny, concerning which there is no such ground.
^'Ontogeny includes, as the developmental history (Entzcick-
lungsgeschichte) of the separate individual, all those
changes of form which the individual undergoes from its
point of origin, the fertilized egg cell, to the state of sexual
maturity." ^^

The terms ontogeny and ontogenesis, introduced into bi-

272 The Unity of the Organism

ology by Haeckel, have been exceedingly useful, and their
usefulness depends largely on the fact that the root ontos
refers to a living being, an organism as a totality, so that
coupled with the term genesis, the reference is to the entire
cycle of the being, and not merely to some particular stage
of that cycle, as is the case with the term embryogeny. The
word embryo7i, the back-bone of embryogeny, embryology,
and the like, means, as the Greek dictionaries tell us, "the
fruit of the womb before birth." It is synonymous with the
Latin foetus. In other words, the center of reference of all
terms containing the root being primarily to one stage, and
that a very immature one, of a higher organism, it may
be held with considerable justice to be inapplicable to the
development of such lowly creatures as the protozoa. But
to define ontogeny so as to exclude reference to the develop-
ment of the protozoan or any other organism is not only
utterly unjustifiable, but deserves unqualified scientific con-
demnation, because, as we have seen, it gives persons not
well informed and so not in position to be on their guard
against being misled, a narrow and false conception about
organic development. The full mischievousness of this sort
of limitation is seen only by looking a little more into details.

Development of Stent or as an Example of Protozoan

Ontogeny

The familiar "trumpet animalcule," Stentor, found in fresh
water ponds almost everywhere and figured in many books,
will serve our purpose well. Numerous zoologists have made
this animal the object of their studies, one of wliich only, by
H. P. Johnson, will be drawn upon. The case of Stentor is
the more instructive in that its mode of propagation is
chiefly if not entirely that of "simple cell division" — to use a
phraseology that is pleasing to simple elementalism.

Before entering upon an account of the development of

Organisms Consisting of One Cell ^^S

Stent or, it is to the point to hear what Johnson has to say
touching the reality of the process as compared with the
develo})ment of a metazoan. "Tlie conception," he says,
"that the development of a new infusorian by the process
of fission is an ontogenetic development, comparable in some
respects to the development of a metazoon, has impressed
itself strongly upon me in the study of fission in Stentor/' ^"^
The course of events in the multiplication and development
of the animal is so illuminating that I reproduce four of
Johnson's figures, figures 11, 12, IS and 14, and would urge
the reader unacquainted with the subject but wishing to
get at the kernel of the position here defended to consult
the original memoir, especially for the anatomy and ontogeny
of the organism.

The main exterior body-parts to which attention should be
directed and which are indicated on the figures are: a. z.,
aboral zone^ h. p., buccal pouchy cl., cilia^ c. v., contractile
vacuole, ejc. p., excretory pore of contractile vacuole, I, line of
division, l.b.s., left boundary stripe of ramifying zone, o, mouth,
p., peristomal band, r. z., ramifying zone, vel., velum.

The processes of division and development are so intimately
associated as to be inseparable. "The first sign of fission," says
Johnson, "is the formation of a rift (the anlage of the new
aboral zone) in the pellicula and ectoplasm near to and almost
parallel with, the left boundary stripe of the ramifying zone." *^
(figure 11 a. z.) By examining tlie figures the reader may
follow quite satisfactorily the main events. The first step in the
develojmient of some of the new parts should be specially noticed.
The aboral zone, for example, as indicated in the quotation, is
initiated as a rift through the ectoplasm running down the side
of the animal's body, hence having no connection whatever with
the original aboral zone. A point of special interest in this
fact is that the organ in question for the new individual does
not arise from the same organ of the old, or parent individual,
either by division or budding. And this de novo mode of origin
is that followed by a whole series of organs and tissues ; the cilia
and membranellae of the aboral zone; the mouthy velum, and
pharynx; the frontal field; the ramifying zone; and tlie con-

cv:.-,

;-*->

i.

c.v.--

[s;

51}

r.-z.— ;^

l.h.s.4

m

If

FIGURE 11

FIGURE 12

FIGURES 11, 12^ STEXTOR CAERULEUS ( AFTER JOIIXSOX).

a.z.,^ adoral zone, b.p., buccal pouch, cv., c.v.,^ contractile vacuole,
d.a.z.,^ distal extremity of adoral zone, cx.ji., excretory pore of con-
tractile vacuole, f, f, frontal field. 1, 1,^ line of fission, mgn.,
meganucleus. o. o\ mouth, p, pS peristome band, r.z., r.z.,^ rami-
fying zone, ^•el'., velum.

274

vc

o-.^

r.v.

-r.z.

1

FIGURE 13.

FIGURE 14.

FIGURES 13, 14

275

276 The Unity of the Organism

tractile vacuole and excretory pore. The origin of the mem-
branellae in this way particularly appealed to Johnson. "The
gradual evolution," he says, "of structures so complicated as
membranellae, from a mass of indifferent protoplasm, is very
striking." *'' What he has especially in view is that these "or-
ganula," as he calls them, arise not from the ectoplasm, to which
in the adult they seem to pertain, but from the endoplasm.

Although Johnson was not much of a speculator, he was
still on the lookout for questions of general interest. "Our
ignorance," he remarks, '*of the primum movens to a neofor-
mation is complete. We can only say it lies in some peculiar
molecular condition that incites the duplication of existing
organs. And the working out of the impulse thus given
is only partly dependent upon temperature, food, the size of
the individual, or even as Balbiani's and my own experiments
in merotomy show, upon the intact condition of the organ-
ism." "^^ The reader should not fail to see that this is an
obvious, though somewhat indirect, recognition of the organ-
ism as a cause of developmental phenomena — of appealing
to the organism as a causal explanation of observed occur-
rences. In saying that the primum movens to organ pro-
tluction lies in "some peculiar molecular condition," the just
clainis of the potency of elements (of some sort) is recog-
nized. But no one should fail to notice the qualifying term
peculiar appended to molecular. The molecular condition
capable of producing the observed results is no general con-
dition; it is a particular condition. And particular how.'^
To the organism possessing the organs to be duplicated.
When the discussion of a purely objective case like this
proceeds normally, the reference is entirely to the organism
and its organs and tissues, and the conception cell does not
enter into it in any way. For example, there is no occasion
whatever even to refer to the nucleus. If the idea of the
cell is brought in at all, it is lugged in purely arbitrarily.

One of the things that h^ts given enibryology its great

Organisms Consisting of One Cell S77

interest, since the doctrine of evolution became established
in biology, is the fact of rudimentary^ often transitory,
oi'gans wliich appear in the course of the individual develop-
ment. Johnson gave special attention to two such organs
in Stentor, the ring-canal and the peristornal-band. The
former is a canal in the endoplasm, just beneath the aboral
zone and running parallel with it. It is present only in
the newly produced posterior zooid, its complete atropliy
occurring soon after fission. Johnson proved it to originate
in connection with the contractile vesicle.

Tlie peristomal band (figure 12 p. p.) is a narrow, clear
band inside of and running parallel with the aboral zone.
It also entirely disappears some time after fission. It is
believed to represent the peristome of the lower Heterotricha ;
tliat is, like so many rudimentary organs of the metazoa,
it is supposed to be an ancestral structure; to have, in other
words, a racial significance. It will be noticed even from
this imperfect description of division and development that
one of the two new animals, the posterior, resulting from
division, undergoes most of the development. It alone, or
very nearly alone, takes on new organs. It may therefore
very well be called the offspring, the anterior animal being
distinguishable as the parent.

The Terms ^'Embryology'''' and ''Ontogeny''^ Inevitably Used
by Investigators of Protozoan Reproduction

The futility of supposing practical science will conform
to a definition drawn up in the interest of a grand theory
but in defiance of a great body of facts, could hardly find
better illustration than in the persistence with which students
of the Protozoa speak of the ontogeny and embryogeny of
the creatures despite efforts like those quoted above to re-
strict the term to the metazoa. Looking at these illustra-
tions a little further, let us take Valentin Hacker's work on

^78 The Unity of the Organism

the Radiolaria. In the general part, entitled Form and
F orm-develo pment in the Radiolaria, of his splendid report
on the collections of this group made by the German Deep-
Sea Exjjcdition, not only do we find a section Ontogenesis of
Variations, but facts and questions of ''^ontogeny'" are scat-
tered throughout the whole j^art, thus : "The other sort of
variability may be in large part referred back to changes
in some of the elementary processes which normally co-
operate in the ontogeny of the skeleton, especially to be
considered being the secretory and sprouting operations." ^■'
And Hacker laments that in spite of the great quantity of
excellently preserved material at his disposal he was unable
to work out the "complete embryology" (EntwicKlungs-
geschichte) of a single group of Tripylea, though he was
able to add largely at many points to previous knowledge.

From the standpoint of descriptive embryogeny probably
the most serious gap in our knowledge of the development
of tlie Radiolaria is the scarcity of information about the
growth of the adult animal from the swarm spores. Thanks
to several zoologists, among the latest of whom is Borgert
particularly, we know quite fully the mode of spore or
gamete production in several species. The great number,
small size, and sim])le structure of these germinal elements
in species like Aulacantha leave no doubt that their growtli
to full sized animals is an elaborate operation involving
many stages and kinds of differentiation.

We have now gone far enough into the structure and de-
velopment of the higher protista to make it indubitable
that there is a mor])hology, individual and comparative ; an
embryology, also individual and comparative; and a physiol-
ogy, likewise individual and comparative, of this great sub-
division of the animal kingdom, not a whit less definite and
hardly less rich and varied, though less elaborate as to
individual animals than in the subdivision known as metazoa.
In the light of the great body of knowledge now available.

Organisms Consisting of One Cell

279

only a tithe of which has been used in this review, it is hard
to see how any one can avoid recognizing that the fact that
the animals usually consist of a single cell, is really of
secondary importance. Neither descriptively nor interpre-
tatively (if one insists on making a sharp distinction between
the two) do the generalized elements cytoplasm and nucleus,
lield to be the irreducible minima of the cell, throw any but
the vaguest, most general light on innumerable of the struc-
tures and processes brought under notice.

REFERENCE INDEX

1.
2.
3.
4,

6.

7.

8.

9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.

PI.

Lang

Hartog

Jennings

Haeckel (1884-87)
Haeckel, (1884-87)

120, fig

Cushman

Calkins ('10)

Calkins ('10)

Stohr

Maurer

Giinther

Sharp

Sharp

Sharp

Sharp

Sharp

Sharp

Sharp

Sharp

Sharp

Calkins ('10)

Shipley and Macbride . .

Piitter

Kofoid and Christiansen.

Haeckel ('03)

Minchen ('12)

3 27. Ward 159

138 28. Meyer 146-148

114 29. Beneke 789

1664 30. Moore 352

31. Moore 353

9 32. Dobell 505

1 33. Marshall, C. E 648

91 34. Burnet 61

79-86 35. Balfour ill

36 36. Balfour 1

1102 37. Balfour 2

553 38. Balfour 10

67 39. Korschelt

72 ('95)

77 40. Korschelt and

80 ('02) 1

82 41. Korschelt and Heider

102 ('02) 5

45 42. Macbride 1

87 43. Van Beneden 325

100 44. Meisenheimer 251

43 45. Johnson 518

28 46. Johnson 501

267 47. Johnson 503

34 48. Johnson 511

492 49. Haecker 650

79

and Heider

Heider

2

Chapter X

HISTORY OF THE ATTEMPT TO SUBORDINATE
THE PROTISTA TO THE CELL-THEORY

T T is important to learn how the attempt to subordinate
■•-protozoans and other protista to cells has fared in the
history of knowledge of these minute organisms. It was a
genuine surprise to me, as I imagine it may be to many
zoologists orthodoxly drilled in the cell-theory, to find how
much dissent there has been and still is among the able
investigators of the protozoa, from this mode of treating
the little creatures.

Clash Between Ehrenberg and Du jar din a Special Case of
the Conflict Between Organismal and Elementalist

Conceptions

The erroneous appraisement by many recent authors of
the work of Ehrenberg will serve as a starting point for
what needs attention under this head. Few names are bet-
ter known in protozoology than C. G. Ehrenberg, whose
monumental work, Die Infusionsthierchen als I'olkommene
Organismen, holds some such place in protozoology as Lin-
naeus' Systema Naturae holds in zoology and botany gen-
erally. Yet it is the custom of most writers to regard it
as a great depository of facts, but antiquated and er-
roneous in its interpretations. The view expressed by Locy
is typical : "His publication was almost simultaneous with
the announcement of the cell-theory (1838-1839), the ac-
ceptance of which was destined to overthrow his conception

280

Attempt to Subordinate Protista to CcU-Theory 281

of the protozoa, and to make clear that tissues and organs
can belong only to m.ulticellular organisms." ^

If one looks into Ehrenberg's conception that "was
destined to be overthrown," and the controversies it pro-
voked, a very significant thing comes to light. He finds
repeated reference to the fact that prominent among those
who lielped to overthrow Ehrenberg's false teaching was
Felix Dujardin. The current form of statement of the dif-
ference between these two naturalists may be illustrated by
the following from Calkins : "A formidable opponent soon
appeared in France — Felix Dujardin — who, influenced by
long study of the Rhizopoda, came to the conclusion in
1835, that the marine forms (Foraminifera) which up to
that time had been classed with cephalopod molluscs, are in
reality the simplest organisms, composed of a simple homo-
geneous substance which he called 'sarcode.' " "

The reader will recognize in the clash here indicated only
another special instance of the ages-old conflict between the
organismal and elementalist conceptions of living beings.
But this instance is suflicientl}^ important in both its theoret-
ical implications and its practical consequences to merit
a somewhat close examination. To begin with, particular
notice should be taken of the type of elementalism upheld
by Dujardin, namely, that of a simple homogeneous sub-
stance as the basis of all life. This finds expression in his
sarcode theory, which has cut a large figure in later specu-
lative biology. The conflict between Dujardin and Ehren-
berg was first and foremost theoretical. The kernel of the
former's theory was that there must be a substance of
organisms more fundamental than organisms themselves,
while Ehrenberg stood for the view that organisms, no mat-
ter how simple, must still be organized. He contended that
all the organisms we actually know, including "Infusions-
thierchen" (and for him practically all microscopic organ-
isms came under this term) are demonstrably organized.

282 The Umiii of the Organism

Uiat is, possess organs.

That there may be no question as to the essential cor-
rectness of the statement that this conflict was primarily
one of theory, let us listen to Dujardin himself. "Among
the authors," he says, "who have written on the Infusoria,
some, as Leeuwenhoek, have attributed to these animals a
very complicated organization, while others, as Miiller, would
see only a glutinous homogeneous substance * (mera gela-
tina). This last opinion, adopted by Cuvier, Treviranus
and Oken, appeared henceforth the most probable, when
M. Ehrenberg came boldly forward in 1830 to show to the
learned world evidences which he believed he had found,
but which unfortunately no one else has been able to con-
firm, of a richness of organization of the Infusoria." ^

From this passage alone the inference could be drawn that
the difference between the two men was strictly one of ability
in observation — of what each was able to see when examining
very minute creatures. But another passage lets the cat
out of the bag. "M. Ehrenberg, who, guided by false anal-
ogies, has gone even beyond Leeuwenhoek in ascribing to the
Infusorians a prodigious wealth of organization, supports
himself on the principle that 'the ideas of size are relative
and are of little physiological importance.' This principle
is only a consequence of a preconceived idea of the unlimited
divisibility of matter. Now in supporting the absence of
all limitations to the divisibility of matter to be a law of
nature — and a mass of chemical and physical phenomena
seem to prove the contrary — that law would not suffice to
prove the possibility of a very complex organization beyond
a certain minimal limit of size ; for it is known that many
pliysical and dynamical phenomena are considerably in-
fluenced or even inhibited by molecular action when the

* The original wording should he noted: "n'ji onf vovU'e le j^lns souvent
qu'une substance . . ." — the old familiar story of seeing what one wants
to see rather than what is actually hefore his eyes.

Attempt to Subordinate Protista to Cell-Theory 283

bodies or intervals which separate them are very small. . . .
It is more in keeping with the laws of physics to admit that
in these small animals, liquids are taken in by simple im-
bibition; as it is more in keeping with rules established by
analogy not to assume that the plan of higher organisms
can be reproduced in these very small beings, since we see
the elements of these organisms, blood globules, muscle
fibers, and capillary vessels, instead of undergoing a pro-
gressive diminution in size in the smaller vertebrates, show-
ing almost the same size in the mouse and in the elephant." ^

In other words, the ph^^sical theory supported by certain
facts of structure and function in larger animals (rather
tlian any theory of organic evolution) led Dujardin to be-
lieve that such minute living beings as Infusorians must be
structureless and beyond question these tlieoretical views
largely influenced, and influenced harmfully, the results of
his observational studies. This fact deserves emphasis be-
cause current presentation of the subject makes it appear
tliat Ehrenberg was theoretically all wrong while Dujardin
was theoretically all right.

Ehrenberg went astray not in defending the theory that
Infusion^thierchen possess organs, but in claiming for them
particular kinds of organs which they do not possess. Con-
vinced as he was, largely on a priori grounds, that the}' must
be organized, and knowing no other kind of organization
than tliat of the larger animals with which he was familiar,
he brought to his microscopic researches a mind prepared
to make the most possible of the general resemblance many
of the little creatures he studied bear to ordinary animals.
From pole to pole and in all depths of the ocean, he said,
live minute animal forms which resemble higher animals
''wie Ahdrilcke einer Schablone'' — like the impress of a mould.
And that the little creatures are genuine organisms seemed
to Ehrenberg to be supported by tlie fact that the myriads
of them fall into species, genera, families, and so on, as do

284 The Unity of the Organism

higher animals. His position cannot be fully understood
without taking into account his view that the protozoa,
being part and parcel of the animal kingdom, are subject to
its general laws, that is, modes of life, distribution and classi-
fication of that kingdom.

In this fact hardly less than in the structure of individuals,
he saw proof that the Infusoria are complete organisms.
Guided by these theoretical views, the warrantableness of
which later researches have made many times greater than
they were when Ehrenbcrg propounded them, it is not sur-
prising that he was led to interpret into various parts he
could see only imperfectly, resemblances to the organs of
higher animals, which resemblances did not as a matter
of fact exist. The stomachs, hearts, genital organs, and
so on, which he believed he saw in many of the species, dis-
appeared before the criticism of Dujardin, Kollicker, von
Siebold and others. But here is the point of chief theoretic
importance. Although these particular organs went down
before criticism, criticism by no means deprived the animals
of all organs. It is in neglect of this last fact that current
teachings do Ehrenberg injustice. His "conception of the
protozoa" was destined to be overthrown only as to the
sort of organization he believed them to have. It is gratify-
ing to find that in this conclusion I am in essential agree-
ment with so eminent an obsei*vational student of the pro-
tozoa as C. C. Dobell. In a recent quite remarkable essay
this author writes, "To my mind, Ehrenberg (1838) in
spite of his incorrect interpretations in matters of detail,
was far nearer to the truth when he saw Protista as h^olkom-
mene Organismen' than any more modern biologist who re-
gards them as analogues to parts of multicellular beings." ^

As between tlie conception of organization in all living
beings, no matter how small and simple, and the conception
of living beings so small and simple tliat they are without
organization, there can be no question that all inductive

Attempt to Subordinate Protista to Cell-Theory 285

knowledge favors the former and tends to refute the latter;
and in so far as Ehrenberg stood for the former and Du-
jardin for the latter the evidence surely supports the views
of the German and opposes tliose of the Frenchman.

This brings us to a highly important practical point. I
mentioned a little while ago that Dujardin's theoretical
views influenced harmfully his observational work. In sup-
port of this statement the reader is asked to compare the
monographs by Ehrenberg and Dujardin already mentioned,
giving special attention to figures of the same animal pre-
sented in each. No one will fail, I believe, to recognize the
greater truthfulness (disregarding the relative merit of
draftmanship and publication) of many of Ehrenberg's il-
lustrations, especially as regards the internal stinjcture of
the organisms. That tlie diff'erence cannot be attributed
altogether to Ehrenberg's superior powers of observation
seems certain from the fact that Dujardin made out numer-
ous points about the cilia of various species which were un-
known to Ehrenberg. Both Dujardin's observations and his
scheme of classification appear to have been largely influ-
enced by his sarcode theory: i.e., his theory of structureless-
ness. "The numerous genera which one establishes," he
says, "in the family of the monadinians, are distinguished
therefore only by the number and position of the locomotor
filaments and by the most habitual form of the body and of
the appendages." ^

Prepossessed by the idea of structural diversity and com-
plication in the creatures of the microscopic world, Ehren-
berg directed his attention primarily to their internal make-
up, described things that do not exist there, and overlooked
various external parts. Dujardin, on the other hand, pre-
possessed by the idea of internal structurelessness, of homo-
geneity, fixed his attention more on the external parts and so
was able to surpass Ehrenberg in describing these, but also
to correct various of his opponent's erroneous interpi*eta-

286 The Unity of the Organism

tions of internal structure. But while Dujardin's greater
merit in these respects was undoubted, his lesser merit in
describing the internal structure is quite as undoubted, and
more vital in that it involved serious practical consequences.
The difference in preconception of the two naturalists made
Ehrenherg the better practical anatomist of the protozoa.
It will have been noted that Dujardin's opposition to Ehren-
berg did not primarily involve the question of the applica-
tion of the cell-theory to the protozoa, both men having
published their main works before that theory was pro-
pounded.

Modern Opposition to the Effort to Make the Protista Con-
form to Cellular Element alism

We noAv pass on in our examination of historical opposi-
tion to the conception that unicellular plants and animals
are "organisms without organs," into the strictly modern
period during which the effort has been to bring the protista
"into conformity with the narrow bounds of cellular elemen-
talism."

(«) The Position of Friedrich Stein

I suppose all protistologists would agree that there has
been no greater worker in microscopic natural history dur-
ing this period than Friedrich Stein. His Der Organismus
der Infusionsthiere (nach eigenen Forschungen) is no less a
fundamental and indispensable part of the library of every
student in this field than is Ehrenberg's great work. That
Stein "was never an ardent advocate of the simplicity of the
Protozoa," as Calkins expresses it, is well known to all
zoologists acquainted with his writings. Both Calkins and
Dobell quote the following sentence from him, which not only
shows his skepticism about the unrestrained applicability of
tlic cell-theory to the protozoa, but indicates the sort of

Attempt to Subordinate Protista to Cell-Theory 28T

limitation to that application which he believes necessary.
"One must ever hesitate to consider the fully developed In-
fusoria as unicellular organisms, for they are not merely
cells that have undergone further simple growth, but the
original cell structure has given place to an essentially dif-
ferent organization which is entirely foreign to cells." ^ That
is, the cell conception applies to these animals, according to
Stein, only when they are in the earliest or geniiinal stages
of their lives. This view is brought out still more clearly
by the following comparison which he makes between the
individual development of a unicellular and a multicellular
organism. "The germinal spheres or embryonal cells of
the Infusoria do not behave at all like the egg cells of the
higher animals. By a process of fission [these latter] break
up {zerf alien) into an aggregate of smaller embryonal
bodies, the constituting cells (the germinal spheres of the
Infusoria), w'hich transform themselves just as they are
into the embryonic body sarcode, the kernel [At^r/i] becom-
ing the nucleus, of the young Infusorian. The embryo of
the Infusorian is therefore in the strictest sense of the word
a unicellular organism." In this sense, and in this sense
only. Stein goes on to say, he subscribes to the doctrine that
the Infusoria are unicellular. Stein's conception of the
adult Infusorian as contrasted with the embryonic Infusor-
ian was probably influenced by his having mistaken an
Ascinetan, parasitic in certain ciliates, for embryos of the
hosts, and on this error he based his theory that these
ciliates pass through an ascinetan stage in their ontogeny.
But this error does not invalidate his statement of the funda-
mental difference between unicellular and multicellular or-
ganisms as to the sort of transformation undergone in their
individual development. Wherever sporulation occurs,
growth of the spores into the adults would exemplify Stein's
main point, and this point is of capital importance as we
shall contend more at length later.

288 The Unity of the Organism

(b) Position of Hua;ley, R. Hertmig and Others

The views of Huxley on the nature of organisms and cells
give him an interesting place among those who protest
against the current cellular interpretation of the protista.
After mentioning Vorticella, Caulerpa and "Roesel's Pro-
teus," as organisms in which there is little or no histological
differentiation, he says : "It is true indeed that the difficulty
with regard to these organisms has been evaded by calling
them 'unicellular' — by sup]>osing them to be merely en-
larged and modified simple cells ; but does not the phrase
'unicellular organism' involve a contradiction for the cell-
theory? In the terms of the cell-theory, is not the cell sup-
posed to be an anatomical and physiological unity, capable
of performing one function only — the life of the organism
being the life of the separate cells of which it is composed?
and is not a cell with diif'erent organs and functions some-
thing totally different from wliat we mean by a cell among
higher animals? We must say that the admission of the
existence of unicellular organisms appears to us to be vir-
tually giving up the cell-theory for these organisms." ^
While the argument Huxley is making differs in important
respects from that which we are developing, these statements
make it obvious that, as Dobell remarks, Huxley realized
"there was something wrong in the application of the cell
theory to the protista." We shall speak further of Huxley's
views in another connection.

Even Richard Hertwig, staunch believer as he is in the
conformity of the Protozoa to the "laws of cell-life," recog-
nizes that harm has been done by pushing the cell-theory
too hard in the interpretation of the protozoa. "A whole
series of instances," he writes, "show how the effort to subor-
dinate the protozoa to experiences with metazoan cells and
to adapt them to the straight- jacket scheme devised for
metazoan cells has led to errors," ^

Attempt to Subordinate Protista to Cell-Theory 289

Many other expressions of dissatisfaction with prevalent
notions about the simpHcity of the protozoa could be cited
from the very latest writings touching the subject from quite
other directions tlian those of morphology and development.
Thus Jennings says concerning the activities of the proto-
zoan, "The writer is thoroughly convinced, after long study
of the behavior of this organism, that if Amoeba were a
large animal, so as to come within the every-day experience
of human beings, its behavior would at once call forth the
attribution to it of states of pleasure and pain, of hunger,
desire, and the like, on precisely the same basis as we attri-
bute these things to the dog." ^^

And M. M. Metcalf in a recent address reviewing the
nuclear phenomena lately discovered in various species of
Amoeba, said : "With such phenomena as these demonstrated
in an amoeba, no zoologist can dare again to apply to any
organism the adjective simple. In the behavior of its nuclear
elements Amoeba is as complex as is man himself."

But the most radical and ^aolent pronouncement against
the cellular conception of the protista that has ever been
made, comes from one of the ablest and most active students
of these organisms, C. Clifford Dobell, whose writings have
already been incidentally cited. A closer acquaintance with
his view will appropriately terminate the historical part of
our discussion.

Dobell's notable essay leaves no reader in doubt about the
nature of this author's disaffection, or as to the doctrinal
reforaiations he holds to be necessary. The application of
the cell-theory to the Protista is wholly unjustifiable and has
been and is now more than ever before a serious hindrance
to the advancement of positive knowledge and sound inter-
pretation of this great subdivision of the organic world.
Coming to closer quarters, his contention is that the protist
body does not correspond to a minute fragment of the meta-
zoan body, one of its myriads of cells, but to the whole body.

290 The Unity of the Organism

"The body of a protozoan is not the homologue of a single
cell in the body of a metazoan, and hence the succession of
individuals formed from one conjugation to the next, is
not comparable with a metazoan body any more than a
swarm of bees is comparable with an elephant." ^^

The reformation proposed is to cease calling the protista
unicellular and to recognize that they are non-cellular.
"The essential difference between the structure of protista
and that of other organisms is properly and objectively ex-
pressed when we describe these as cellular, those as non-
cellular. The concept 'cell,' derived from a study of cellu-
lar organisms, is a fairly simple one. It is quite clear that
the correct antithesis in the present case is between cells
and not-cells, and not between many cells and one cell — as
has hitherto been universally assumed." ^^

The cell concept which Dobell believes to be "fairly sim-
ple" is presented thus : "The investigation of an immense
number of organisms has brought to light a most important
fact, namely, that the protoplasm of a living organism al-
ways consists of two elements, a nucleus (or nuclei) and
cytoplasm.

"Now in a very large number of multinucleate organisms
the cytoplasm is subdivided into a number of definite com-
partments, each of which encloses a nucleus. These cyto-
plasmic subdivisions with their enclosed nuclei we may call —
following the ordinary usage — cells." ^^ The denial of cellu-
larity to the Protista, Dobell bases on the fact that the
individual organisms are not divided up into nucleate masses
of protoplasm.

Other and quite distinct aspects of DobelPs standpoint
are his contention that the terms "higher" and "lower"
have no valid applicability^ to organisms, and that the pro-
tista are not "primitive" and "ancestral" relative to man
and other large animals and plants, in an evolutional sense.
"There is no more reason," he says, "to suppose that these

Attempt to Subordinate Protista to Cell-Theory 291

organisnis, with their conij>lcx and peculiar structures and
life-histories, are the beginnings of man than that man is
the beginning of them."^^ The far-reaching consequences
of Dobell's views, should they prevail, are indicated by his
remarks about evolution. "Wliy should it always be taken
for granted that by 'Evolution' is meant *an upward prog-
ress from Protozoa to jNIan'? This is only one hypotliesis
of organic evolution. That evolution of some sort has taken
place in living beings I regard as certain. But, that evolu-
tion of the Haeckelian 'Amoeba to ^Nlan' type has not oc-
curred I regard as equally certain. We can certainly be-
lieve in evolution without believing in this dogma." ^^

General Conclusions From Examination of Knoidedge and
Views as to the Nature of Uni- and Mitlti- cellular

Organisms

We may now ask ourselves, what comes of this some-
what extensive examination of the structure and function
of the Protista, and of the history of discovery and opinion
concerning them.^ Whatever else comes, I do not see how
any open-minded person can escape seeing that the practice
of thinking about these small beings as conforming in es-
sence to the "simple cell" is unnatural, impedimental of
progress in sound knowledge, and ought to be abandoned
forthwith. But how abandon a practice based on a general
theory which has served to unify so vast a multitude of di-.
verse and, at first sight, apparently quite isolated facts .'^
That the cell-doctrine applied to the Protozoa has served
such a purpose is beyond question.

The point deserves concrete illustration. There has re-
cently occurred in the dinoflagellate collections of the San
Diego region an organism so different from any hitherto
described as to elicit the exclamation "a remarkable thing!"
That Doctor Swezy, to whom has fallen the task of describ-

292 The Unity of the Organism

ing it, was able to make the hypothesis that the creature is
unicelluhir, was undoubtedly a very great help toward mak-
ing out the details of the structure and instituting the com-
parisons preliminary to assigning the organism to a place
in the system of classification. The generalized observa-
tional knowledge which is the backbone of natural science is
impossible without a central concept or mental construction
of some sort to which new observations can be brought for
testing and standardization, and finally for assignment to
their proper place in the general scheme. Sound science as
well as common knowledge refuses, consequently, to abandon
its general views, especially if these have been truly helpful,
even though their inadequacy, or actual erroneousness may
have become manifest. The oft-repeated statement that
a wrong theory is better than no theory has the sanction
of psychology and logic, as well as of the universal concaten-
ation of nature. Outgrown or erroneous theories must be
supplanted rather than abandoned. Their places must not
be left vacant, but filled by other and better theories.

These general considerations taken by themselves make
it extremely improbable that DobelPs proposal to reform
interpretation of the protista as non-cellular instead of
unicellular will meet with wide approval. Non-cellularity is
pure negation, and so lacks the essentials of a "working
theory." Furthermore, from the side of clear objectivity,
a proposal which involves the denial of celhilarity to sucli
an organism as an amoeba or a gregarine because only one
cell is present in it, violates the principles of sobriety and
consistency, so vital to true science, and ought not to be
sanctioned.

The reformation of theory touching the cellular nature
of the protista which it seems to me is demanded by the
facts will, I hope, be apparent to any one who has followed
the discussion to this point. The concept cell must be held
in strict subordination to the concept organism in this as in

Attempt to Subordinate Protista to Cell-Theory SOS

all other portions of the living world, and to make this
effective the concept organism must be given greater defin-
iteness than it has generally had. The classes of fact which
have been sampled in the preceding pages furnish the basis
for both these readjustments.

First as to the subordination of cells to organism. Let
attention be directed to the myriad of natural objects called
living beings and cells rather than to concepts about them.
Wherever in the living world structures occur which com-
petent judges agree to call cells, these are structurally part
of and functionally dependent upon, and therefore strictly
subordinate to, living beings. This subordination is seen
in the fact that cells arise as a consequence of the activities
of living beings. This mode of origin is most obvious in
the individual development of the larger plants and animals
where growth is accompanied by a resolution of the growing
body into a great number of such structures.

It seems that racially as well as individually, cells were
produced by living beings. This I say seems to have been
the case, for be it always remembered that certainty as to
how either living beings or any of their parts arose in the
first instance — if indeed there was a first instance — is wholly
impossible for positive science. However much we may
speculate on the subject we have no right to permit the
speculations to exercise more than a secondary influence on
observationa^l and ^interpretative results touching actual
living beings.

So far as the bacteria and other living beings near or be-
low the limits of microscopic vision can be supposed to rep-
resent earlier stages in the evolution of the living world,
they indicate that beings much smaller and considerably sim-
pler than cells existed long before cells.

And functionally as well as developmentally, cells are
subordinate to the living beings to which they belong. This
is most manifest in animals which, like man and other higher

^94 The Unity of the Organism

vertebrates, perform a great number of voluntary acts. In
such cases as those of the voluntary muscles, the muscle
cells are used hy the living being for its needs as strictl}'
as are the whole muscles or the limbs and other primary
voluntary members of the body.

But while the functional subordination of cells to the
living being is seen most conspicuously in the active use of
tliem by the higher animals as they perform their voluntary
acts, this sort of subordination is exceptional, taking the
whole world and all its operations together. The most funda-
mental, and as it seems, the strictly universal aspect of the
functional subordination of cells is in the assimilation of
food and concomitant breaking down of synthesized organic
substances to produce the basal processes distinctive of each
individual and kind of living being. In its metabolic proc-
esses the living being's supremacy over its cells is most uni-
versally manifest. The identity, structural and functional,
which the individual organism maintains by converting nu-
trient matter into its own self, and for its own use, is ac-
complished largely if not wholly by means of its cells.

The supposition that the cells themselves, taken inde-
pendently of the organisms to which they pertain, have
power to develop and perform the metabolic operations
characteristic of each species and each individual organism,
seems a necessary consequence of the cell-tlieory in its full
modern development, in the conception, that is, which sees
in the cell the "key to all biological problems." But it is
hardly necessary to remark that tliere is not an iota of di-
rect evidence that cells possess such power. The only obser-
vations we have upon which such an interpretation could be
forced, even by tlie most intellectually unscrupulous meth-
ods of forcing evidence, are tliose on tlie viability of isolated
cells and tissues (see Chapter 6).

As a matter of fact the evidence from this source not
only does not support the doctrine of the supremacy of

Attempt to Snhorilinate Protista to Cell-Theory S05

cells but strongly favors the supremacy of the organism.
Let us suppose, for example, a specially skillful technician
has isolated all the voluntary muscle cells of a cat and kept
them alive indefinitely. Would any cellular elementalist
be so courageous as to contend that the cells would under-
go the contractions coordinated in quantity, force and speed,
which are involved in the animal's crouch-and-spring to
catch a rat? But suppose such coordinated contraction
of the isolated cells should take place. How could the fact
be explained? Surely in no way that did not recognize
that they were merely doing under the new conditions what
they were accustomed to do under the old ; that, in other
words, in endowing them with the ability to perform these
contractions, the organism had also endowed them with
such a measure of independence of metabolic activity as to
enable them to keep up these operations after separation
from the organism.

One of the most essential things toward putting ourselves
straight in theory as to the relation of the cell to the organ-
ism in unicellular beings, is to get straight on the relation of
the cells to the organism in multicellular beings. An in-
dispensable step toward this latter consummation is to re-
move from our thought and terminology the conception
which holds the metazoa and metaphyta to be "cell-states,"
"cell-colonies" or "cell aggregations," when these terms are
used as though the cells were originally independent enti-
ties. The embryology of the metazoa furnishes overwhelm-
ing evidence that the egg is the organism in its one-celled
stage, and that cell-division during ontogeny is a resolution
of the organism into minute parts very much like one an-
other.

Once we have gone this far in revising the cell-theory we
come to realize the weightiness of the truth that the theory
was originally concerned with parts or elements of larger
plants and animals, and not with these organisms them-

296 The Unity of the Organism

selves. It was the appreciation of the significance of this
fact that made the theory seem to Huxley wholly inap-
plicable to the protozoa. *'How,'' he said, "imagine struc-
tures w^iich are professedly only elements in the make-up
of one kind of organisms, to be the same as structures which
are the whole organism in other kinds of beings.^" This
same difficulty seems to have been the chief influence in lead-
ing Dobell to deny that the Protista can be legitimately
brought under the cell-theory.

I wish to point out that while there can be no doubt
about the great importance of the fact that in metazoa and
metaphyta cells are parts of the organisms, I am unable to
see that the fact necessitates, as held by Huxley and Dobell,
the exclusion of protozoa from the cell-theory. It simply
establishes in the most uncompromising way the subordina-
tion of the cells to the organism in the metazoa and meta-
phyta. If the idea be grasped that cells are among the in-
strumentalities produced by organisms in the course of their
development, individual and racial, with which to carry on
their various activities, it will become apparent that there
can be no objection to modifying the conception of the cell
to make it apply to any structure whether a part of, or the
whole of an organism, which satisfies certain well-established
criteria. When, for example, it is recognized that certain
species of amoebae resemble so closely the white corpuscles
of the blood of many animals as never to fail of recogni-
tion by good observers, the established principles of bio-
logical definition and classification dictate that the two sorts
of bodies be given a common, that is, logically speaking, a
generic name.

But now comes another principle of description and class-
ification which, though no less fundamental than that just
mentioned, has not been as adequately heeded by defenders
of the cell-theory ; the principle, namely, that a genus al-
ways implies species and that these must each be as carefully

J f tempt to Suhordinatc Protista to Cell-Theory 297

described as the genus itself. In other words, sound scien-
tific procedure requires that if amoebae and white blood
coi*puscles are classed together as cells, their- differences
must at the same time be given full recognition. If this be
done, among the many differences that will come to record
are sure to be this : amoebae are organisms, each individual
being complete and independent in itself, while blood cor-
puscles occur only as elements of the blood and lymph of
other organisms. This is a simple statement of fact in the
interest of pure description. But notice what it reveals.
Amoeba appears in a two-fold role, that of cell and that of
organism. But cells of tlie metazoa are, as we have seen,
subordinate to the organisms to which they belong. What,
consequently, are we to conclude as to the relation of the
cell of the amoeba to the organism amoeba.? Manifestly
that the one cell of the amoeba is no less subordinate to the
organism amoeba than the many cells of a worm are sub-
ordinate to the organism w^orai.

While this is merely a presentation of the logic of the
situation, it corresponds to the objective facts of the pro-
tista, and I think must be admitted by any one who will
weigh fully and candidly what has been presented in the
section on that subject.

So much for that part of the reformation of the cell-
theory, in its application to the protista, which concerns the
subordination of cells to organisms in these as well as in
metazoa and metaphyta.

It remains now to see what can be done with the other
aspect of the reformation, namely, that of securing for the
concept organism greater definiteness than it has hitherto
had. For reasons partly valid and partly not valid the
tenns "organism," "organism as a whole" and "organiza-
tion" are believed by some biologists to be too vague to be
scientifically useful. Indeed, a few good authors charge that
these terms have a mystical implication. In reply to this

298 The Unity of ilie Organism

last charge it may be pointed out that any objective term,
no matter how exact and rigidly scientific, is capable of be-
ing given a mystical twist. Think for example, of how the
words substance and force had been and still are being
abused in this way ! Were positive science to eliminate from
its vocabulary all words that have had mystical meanings
imposed upon them, there would be left only words that
have never come into wide and general use. The truth as
touching the mystical implication of organism and organ-
ization is that while no careful thinker would venture to deny
that they may have been thus misused, they have suffered
distinctly less than many other common biological terms
the utility of which when properly used no one ever ques-
tions.

These palliative remarks about the charge of mysticism
are not intended to lessen in any degree the need of giving
greater definiteness to the concept.

We may take as a starting point for this effort the funda-
mental truth that living beings exist whose organization is
so radically different from any with which ordinary obser-
vation acquaints us, as to have been wholly unpredictable
before they had been actually studied. Research on the'
protista and especially those prosecuted during the present
era, have established their uniqueness beyond cavil, and no
other general result of these researches is of greater im-
portance than this.

The appraisement of the fruits of protistology thus in-
dicated came to me gradually in the course of my studies
preparatory to writing the chapter on this subject, and I
was greatly interested to find later that Dobell had reached
the same conclusion. "The great importance," he writes,
"of the protista — to my mind — lies in the fact that they
are a group of living beings which are organized upon quite
a different principle from that of other organisms. . . .
The protista offer us, in other words, a new point of view

Attempt to Suhordwnte Protista to Cell-Theory 299

for looking at the phenomena of life." ^^'

Sometliing of what has been gained or may be gained in
the way of limbering uj) and broadening our minds as to the
nature of living beings is illustrated by the work of f^hren-
berg examined in a previous section. So rigidly limited,
as we saw, was this zoologist's idea of an animal that it
seems to have been impossible for him to believe an animal
could be organized on a plan essentially different from
familiar animals.

Having regard to the whole range of knowledge of pro-
tistan anatomy in our possession, two tilings stand fortli
prominently. First, the organisms present a type (if indeed
we ought not to say types) of organization fundamentally
different from any known among the larger plants and ani-
mals ; and second, the observational evidence is to the ef-
fect that organization of some sort is present in all Pro-
tista. Nor is the phrase "organization of some sort" void
of definite meaning. For a living being to have organiza-
tion is to' have parts of different kinds whose existence and
operations are dependent upon one another, all correspond-
ing to the activities of the special being taken as a whole.
"Of some sort," used in the most general way possible, that
is, as applicable to all organisms whatever, means just so
many sorts as there are sorts of plants and animals in all
the world. Man's sort of organization is man's total struc-
ture, his externo-topographic body members, his gross ana-
tomic parts, his histologic parts, and his chemico-biologic
elements. Likewise Stylonychia's sort of organization is that
protozoan's total structure, macro- and micro-morphologic
and chemico-biologic and so on for all living beings.

And this brings before us one of the great merits of the
organismal as contrasted with the cellular mode of viewing
living beings. The concept organism being committed to not
one sort of organization but only to some sort, is open to
whatever particular organization may be discovered in any

800 The Unitij of the Organism

being. On the other hand, the concept "cell" being com-
mitted to a single type to which it strives to reduce what-
ever being it approaches, is locked, as one might say, against
the vast diversity that actually exists in the living world.
Not only has the cell-theory, strictly understood, no ex-
planation of the structural variety of living nature, but
by its very essence it tends to minimize the significance of
that variety, and to divert attention from it. That the
theory always has been and is now narrowing in its influ-
ences no candid student will try to deny.

The injury that the science of microorganisms has suf-
fered and to which attention has been called in preceding
pages is a notable instance of the tendency of the cell-
theory here criticized.

But does almost limitless diversity in the conception of
"organism" deprive it of value as a generalization? Has
it any of the unifying quality upon which the usefulness of
a scientific theory depends? The answer to this is two-fold.
In the first place, there is just so much unity in the concept
organism as there is in the larger and smaller groups of
the plant and animal kingdoms. On this side the conception
is rooted in comparative anatomy and physiology and tax-
onomy.

But the conception's unifying quality par excellence is
seen in another direction, namely, that of the elements-in-
common of organization in all organisms whatever, so far
as their structure is known to us. In all living beings from
the largest and most complex to the smallest and simplest,
if still visible, the body is differentiated into a surface layer
or coat somewhat firmer and denser than the underlying
more voluminous parts. We know of no living thing without
a skin of some sort. Frequently this is spoken of as a mere
lifeless protective structure. But as a matter of fact it is
tlie organism's organ of contact with its environment, and
so of the utmost importance for the nutritional, respiratory

Attempt to Subordinate Protista to Cell-Theory 301

and responsive functions. Possibly skin and inner mass may
be organization in its lowest terms, though this is not prob-
able. The inner mass is probably never entirely structure-
less. Even the bacteria, formerly described as homogeneous
in their body substance, are now being shown to have con-
siderable structure.

So our guiding star in the study of living beings whose
structure is not known, as for example the ultra-microscopic
beings to which hog cholera is supposed to be due, is that
they are organisms whose organization may be assumed to
consist of at least an outer layer and an inner mass. We
may presume, too, that portions of the protoplasm of the
inner mass are more or less definitely and permanently dif-
ferentiated chemically from the rest, but of this there is
less certainty than of the differentiation of the outer layer.

Our contention that cells are subordinate to organisms
everywhere and always, whether in unicellular or multi-
cellular beings, we may now regard as established.

REFERENCE INDEX

1. Locv 107 9. Hertwig, R. ('03) 3

2. Calkins ('10) 10 10. Jennings 336

3. Diijardin 20 11. Dobell ('11) 273

4. Duiardin 24 12. Dobell ('11) 277

5. Dobell ('11) 274 13. Dobell ('11) 276

6. Dujardin 127 14. Dobell ('11) 300

7. Stein ('67) 22 15. Dobell ('11) 301

8. Huxlev ('53) 265 16. Dobell ('11) 270

PART 1

CRITIQUE OF THE ELEMENTALIST CONCEPTION OF

THE ORGANISM

B. The Production of Individuals hy Other Individuals

Chapter XI

THE NATURE OF HEREDITY AND THE PROBLEM

OF ITS MECHANISM

Heredity the Chief Present-day Stronghold of Biological

Element alism

BIOLOGICAL elementallsm of to-day undoubtedly has
its chief stronghold In the realm of heredity. The
germ-plasm theory, accepted by probably a majority of
biologists as an absolute monarch in the empire of biological
tliought, was elaborated for the sole purpose of explaining
herecHty. In the third chapter of the present work we
looked at certain subsidiary aspects of this theory. The
time has now come for scrutinizing the theory itself.

Heredity has come so conspicuously to the front lately
in connection with plant and animal breeding, in social ques-
tions, and in eugenics, that almost every educated person has
learned something about the splendid progress of knowledge
concerning it. All who have glanced through some of the
numerous books on the subject have seen the pictures of
chromosomes represented as the bearers or the mechanism
of hereditv. They have also learned more or less about unit
characters, so prominent, biologically speaking, in con-
nection with the mode of inheritance discovered by Gregor
Mendel. If the learner's efforts have gone beyond the rudi-
ments of the subject he has become acquainted with "deter-
miners" and "unit factors" of the germinal substance which
are held to explain the characters of full-grown organisms.
There is something bewilderingly fascinating in the qual-

305

306 The Unity of the Organism

ity and scope of these discoveries, and it is not surprising
that many of the leading investigators in the field have been
swept off their feet with enthusiasm for the rehabilitated
germ-plasm theor}^ Thus we hear one prominent student
declare that individual traits are a "veneer," and another
that "analysis of the constitution of the germ-plasm is ad-
mittedly the fundamental problem in the study of heredity."
In other words, the interpretations placed upon the indubi-
table results of the new researches have effected a rejuvena-
tion of the germ-plasm theory of Weismann. Rejuvenation,
I say, because that theory was approaching death and decay
when the rediscovery of the Mendelian mode of inheritance
occurred. It seems as though some students have lived so
exclusively and intensely in the invisible world of "deter-
miners," "factors," "bearers," etc., that for them the or-
dinary world of plants and animals has lost most of its in-
terest if not its reality.

•J

This Dae Particularly to the Discovery of the Interdepend-
ence Between Adult Characters and Chromosomes

of Germ-Cells

In what immediately follows I want to fix attention on the
remarkable way in which a long series of discoveries highly
interesting in themselves, and pertaining to fields quite re-
mote from each other have conspired to increase the plausi-
bility of the old theory that organic beings are caused by
the activities of pre-existent, simple representative units or
elements of some sort.

On the face of the matter two fields of biology could hard-
ly be more sharply separated than that in which falls the
study of the nuclei of cells, and that which occupies itself
with the way color, size, and similar attributes appear in
successive generations of plants and animals. Yet the first,
or cytology, on the one hand, and breeding experiments

Nature of Heredity and Problem of Mechanlsvi 307

conducted under tlic guidance of Mendel's discoveries, on
tlie other, have almost if not quite demonstrated some sort
of interdependence between the chromosomes of the germ-
inal cells of several species of sexually propagating plants
and animals, and such attributes of adults. These demon-
strations are perhaps tlie most important achievements of
biology in the last decades, and they must ever hold high rank
in tlie history of the science.

How do the new discoveries appear when viewed from the
organismal standpoint.^ A study of recent writings on
heredity gives one the impression that elementalist concep-
tions have left cells behind and passed on to chromosomes,
elements which lie at a deeper level as one might express it,
of organic constitution than do cells. ]Much recent discus-
sion of the mechanism of heredity has not been cytological
so much as chromosomological. Somewhere in the first
few pages of nearly all semi-popular books on genetics one
finds diagrams of the egg-cell with the nucleus and its chro-
mosomes represented in due particularity, but with the body
of the Qgg left blank, the implication being that this part
contains nothing significant for heredity. So much has
recent thinking on the "hereditary substance" kept chro-
mosomes in the foreground as "carriers of heredity" that
the most radical elemcntalists might, quite conceivably, grant
that the main mass of each cell, whether p-erm-cell or soma-
cell, may be an organ and so subject to the organism, yet
contend that the chromosomes are not so subject. In fact,
speculations like those recently published by the late E. A.
Minchin on the evolution of the cell appear to claim just
this sort of primacy for chromosomes, or at any rate for
chromatin.

/

308 The Unity of the Organism

Revised Conception of Heredity Essential to Interpreting

This I liter dependence

On the basis of tlie objective evidence what is the prob-
able meaning of the interdependence between attributes of
full-grown organisms and chromosomes of the germ-cells?
There is the utmost diversity of view as to what heredity is
and as to what facts come under it. It seems almost as
though the more the subject is investigated the more diverse
the views become. This I think is literally true for the
theoretical side of the subject, though it is certainly not
true with reference to the factual side. The discovery by
Mendel of the principle of segregation of characters while
they are still latent in the germ-cells, and the elaboration
of this principle by later investigators, is a ])ositive achieve-
ment of high rank, destined to stand for all time. And suc'a
negative results as those of the disproof of telegeny, of the
influence of "maternal impressions," and of the inheritance
of acquired characters in the old pre-Weismannian sense,
nmst be counted as factual achievements of much practical
importance.

Unwarrantable Tendency to Restrict Heredity to Sexual

Propagation

Heredity as used in biology lias to do with the reproduc-
tion of plants and animals. That the growth of an oak
tree from an acorn and of a rooster from a hen's Qgg illus-
trate heredity there can be no doubt. These typify a great
number of cases, all those in which the plant or animal de-
velops from a germ-cell, an exceedingly minute, simple body
as compared with the full grown organism. But what about
reproduction through other means than such cells .^ Is
there heredity in propagation by other means .^^ Much of
the recent discussion of the subject is practically restricted
to heredity among germ-producing organisms ; and some
of the foremost writers on the subject are explicit on this

N of lire of Her edit If and Problem of Mechanism 309

limitation. Thus in the glossary of Heredity/ and Environ-
ment in the Development of Man by E. G. Conklin, we read
that heredity may be defined as "the appearance in the off-
spring of characters whose differential causes are found in
the germ cells" ; ^ and since nowhere in the volume does
Professor Conklin even mention any but germ-cell repro-
duction, we are obliged to assume that for him heredity is a
phenomenon of germ-cell reproduction alone. This seems to
be a case of trying to escape through definition the difficulties
encountered b}' a theory ; in other words, to circumscribe the
theory for the purpose of excluding from Its scope phenom-
ena which can not be made to fit in with it. It is surprising
that so careful a reasoner and observer as Conklin should
have fallen into this pit. A definition of heredity that would
exclude from its operation the growth of a tiger lily from
a bulb, of a sponge from a gemmule, and of an ascldlozooid
from an ascidian bud, is so obviously forced that it ought
to raise a suspicion that consciously or otherwise it is framed
with some other motive in view than that of telling what
heredity is ; and it is unbelievable that such a definition can
gain general and permanent approval.

While not many authorities are so definitely extreme as
this, a large majority of the recent books in which heredity
occupies a prominent place tend to lead the reader thus to
restrict his conception of heredity. Another class of writers,
while tacitly allowing that heredity manifests itself in cases
where germ-cells do not occur, yet take the ground that
sexless propagation is very exceptional and does not need
to be taken particularly into account in elaborating theories
about heredity. Thus in so excellent a book as J. Arthur
Thomson's Heredity we are told that "the exceptions are
trivial compared with the vast majority of living creatures
in regard to which it is certain that each life begins in a
fertilized egg-cell." ^ And on a later page this author ital-
icizes the sentence: "In asexual reproduction the resem-

310 The Unity of the Organism

blance of the offspring to the parent tends to be very com-
plete, and the reason for like producing like is no puzzle,
while the scparated-off j)ortion is a representative sample
of the Avhole organism." '^

One would like to know liow Professor Thomson would
reconcile the first statement with the sum total of facts of
reproduction. We know from his numerous books that few
biologists are more broadly learned on the subject of or-
ganic reproduction than he. It is therefore hardly possible
that he would hesitate to admit that if a complete census
were made at this hour of the individual organisms compos-
ing the living world, the enumeration taking note of all
individuals produced sexually and all those produced asex-
uall}^, the asexually produced would probably exceed in
numbers those produced by the other process. And be it
remembered that in some of the most prolific sub-divisions
of the bacteria, the dinoflagellates, the diatomes, the try-
panosomes, the sarcodinians, various groups of algae, and
even some of the liigher plants and insects, sexual reproduc-
tion, with rare exceptions, has never been seen.

Nor should one fall to recall that in the many groups of
both plants and animals where sexual and asexual repro-
duction alternate in the same species, the individuals pro-
duced asexually are almost, if not always, far more numer-
ous tlian those produced sexually. So far as numbers of
individuals are concerned all zoologists know how small a
part sexual propagation plays in some of the coelenterates,
as the coral-])roducing poly[)s; in most bryozoa ; in several
grou])s of tunicates ; and in some fiat-worms. If one ob-
jects that coral polyps, bryozoan polypides, and ascidian
zooids ought not to be counted as "individuals," the reply
sufficient for the present discussion is that whatever they
should or should not be called they are what give rise to the
sex-cells, the things which are central in the theories of*
heredity. "Germinal continuity," so fundamental in tliese

Nature of Hcrcditij and Vrohlcw of Median is rn 311

theories, is certainl\^ non-existent so far as germ-cells are
concerned in many of these species.

The aim so far has been merely to fix attention on the
tendency of present day theorizing on heredity to restrict
the conception to phenomena presented in reproduction
through the instrumentality of germ-cells of two sorts, male
and female. It is hoped that this brief statement of the
tendency has revealed its unwarrantableness to the uncom-
mitted reader. But since our general enterprise requires us
to perceive its fallaciousness we shall have to examine it in
considerable detail.

UiuimrrantahU Tendency to Restrict Heredity to Adult

Characters

Another serious shortcoming in the way problems of
heredity are treated must be noticed. Reference is made
to the practice particularly by recent geneticists of treating
heredity as though it primarily concerns only the attributes
of adult organisms. To be sure both popular and scientific
observation depart to some extent from this rule. Notice
is often taken of the resemblance to their parents of young,
even newly born humans and lower animals, but even here
the basis of comparison is the adult, the parent. Rarely are
resemblances of the embryo in its many stages of develop-
ment to the embryos of its parents at the corresponding
stages of their development thought of as phenomena of
heredity. Raymond Pearl, in his Modes of Research in Gen-
etics, has pointed out this defect more comprehensively than
any other writer so far as I know. Under the topic, "The
Embryological Methods of Research in Genetics," after
remarking that embryology has been cultivated mainly for
its own ends, he wntes, "Only in a relatively small portion
of instances, has it been directly and purposefully used as
a mode of research in genetics. Yet embryology is the sci-

312 The Unity of the Organism

ence of somatogenesis, which was shown at the beginning to
be one of the fundamental elements of the problem of hered-
ity," and he remarks further: "It is a little difficult to un-
derstand why, with such splendid opportunities as the
embryological method offers, so little light regarding the
hereditary process seems to have come from the embryolo-
gist." *

Importance of Recognizing Heredity as Working hy Trans-
formation Rather Than hy Transmission

Another weak spot in much thinking about heredity even
by some biologists is due to the fiction of "transmitting"
characters from parent to offspring. This appears to have
come from the original meaning of the terms inheritance
and heredity^ which have to do with heirship to property.
Several recent authors have dwelt on the confusion of ideas
that has arisen from this equivocal mode of expression. No
one fails to recognize the difference between the transmis-
sion of stature and the transmission of a farm by a father
to his son. That the difference is partially recognized even
in ordinary discourse is seen by the stated beliefs that bio-
logical heredity is always associated with resemblance. In-
deed, the universality of this association is one of the basal
truths in theories of heredity. The real inappropriateness
about speaking of organic propagation in terms of economic
inheritance is that attention is not called to the fact that the
former is accomplished through a long, regular systematic
series of transformations to which there is nothing compar-
able in the latter.

The objection here made against the transmission idea is
different from that made by most geneticists. Their point
is that the germ-plasm conception excludes the possibility
of any sort of transmission from parent to offspring. Con-
tinuity of germ-plasm is the kernel of their objection. My
main point, on the contrary, does not concern the hypotheti-

Nature of Hcreditij and Problem of Mechamsm 313

cal germ-plasm so much as tlie observable fact that or-
ganic development, whether hereditary or not, is first and
foremost transformative rather than transmissive.

Tendency to Confuse Heredity with Causes of Heredity

Again there is appearing in the strictly modern studies of
heredity a conception that seems both scientifically unwar-
rantable and fraught with possibilities of much harm. This
is the failure to distinguish between heredity itself and the
causes of heredity. Pearl has given tliis the most positive
expression I have come upon. "By heredity is meant the
complex of causes, not now further specified or defined,
which, taken together, determines this likeness or resemblance
between individuals genetically related to each other." ■' It
is to be hoped Doctor Pearl would not wish to be taken quite
literally in this. Indeed, other passages give some ground
for supposing he would not. The point here raised is
probably more an aspect of the general theory of natural
causation than of the specific question of cause and effect in
heredity.

The concept "cause" is meaningless except in relation with
the concept "effect," and since causes and their effects
can not be identical, effects must be as much realities of
nature as causes are ; so if science is to maintain its claim to
objectivity it must devote itself as sedulously to the ascer-
tainment of what the effects are in any given case as to what
the causes are. The eye-color of a child which resembles
the eye-color of an ancestor is an effect and not a cause,
and must be accepted whole-heartedly as such before the
student is in a proper frame of mind to consider the question
of what the cause or causes may be of the observed effects.
To define heredity in a way that implies a disregard of this
general principle can but lead to unbalanced thinking and
effort and to results strongly tinctured with error. If the
position be taken — and unfortunately it is taken by many

314 The Unitfj of the Orgonism

men of science — that the investigation of causes is the main
if not the exchisive function of science, this can mean noth-
ing else than that in the eyes of natural science at least one-
half of all nature is of less importance and interest than
the other half, and that science is privileged to decide which
is the important part. This is another way of criticizing
the practice now so dominant in biology of exalting the con-
cept of causality and degrading that of description. An
important fruit of the present discussion will be, it is hoped,
an exposure of the injury that has befallen theories of hered-
ity from this practice. Nor does our position imply the
notion, held by a few men of science, that the category of
causality is useless in science and ought to be dropped. Far
from it. The causal explanation of heredity is not only a
legitimate but an exceedingly important object of investi-
gation. But it is by no means ^he whole problem or even
the most important problem, the subject of heredity being
regarded in the large and for all time. Perhaps in the
present stage of progress of biology it is the most im-
portant ; but if so I would maintain that at some later time,
wlien the knowledge of causes shall have been advanced out
of proportion to other aspects of the subject, some of these
retarded aspects will become for a period the center of
genetic interest.

The Definition of Heredity Adopted in This Discussion,

with Remarks on Its Application, Especially with

Reference to the Chromatin Theory

We are now in position to fix upon a definition of heredity
which shall recognize that its mechanism is as much a part
of and subordinate to the organism as are all its other parts
and organs. Or, employing the form of expression current
in recent genetics, a definition which shall tactily recognize
that chromosomes, even though bearers of heredity, are
causally explained by the organism in the same sense that

Nature of Hereditu and Problem of Mechanism 315

the hereditary attributes of the organism are causally ex-
plained by tlie chromosomes.

Of tJie many definitions the one that most nearly expresses
the conception that will pervade this discussion is tliat given
by W. E. Castle: "By heredity, then, we mean organic re-
semblance based on descent." " The commendable things
about this definition are its non-commitment to any theory,
and the fact that it puts resemblance in tlie front line along
with the recognition that resemblance is due to descent.
Any adequate definition of heredity must hold the phenom-
enon of resemblance always in clear sight, and this in spite
of the fact that in the Mendelian mode of inheritance the
resemblance may skip one or mo.re generations.

Our further discussion will fall under two heads. First,
we shall make a wide survey of resemblance due to descent
for the purpose of learning how far its connection with
chromosomes actually extends ; whether in a word, the con-
nection is a universal principle. Second, we shall then have
to see what we are justified in supposing to be the nature of
the connection.

It will be noticed that the first statement admits in ad-
vance that to some extent resemblance between ancestors
and progeny is in some xvay connected with the chromosomes.
This admission relieves us of the necessity of an exhaustive
review of the evidence which necessitates the admission.
Though the evidence has practically all been brought out
during the last twenty-five years, it is large in quantity ^nd
widely scattered. Nearly all the semi-popular books, not
to speak of the many serials in technical biolog}^, present
some of it. We may therefore restrict ourselves to such
aspects as will seme our purpose from time to time.

Throughout the vast range of living beings the rule like
'produces like holds sooner or later. I say sooner or later
because there are many exceptions were we to limit the state-
ment to parents and their immediate offspring. No indi-

316 The Unity of the Organism

vidual salpa, for example, ever produces its like. In some
species parent and offspring are very unlike, so much so
that were they not actually observed to be parent and off-
spring, they would be regarded as unrelated and belonging
to different genera. But instead of being wholly unique,
though so unlike its parent, the young returns to its grand-
parent for a pattern; so if we jump a generation the rule
holds after all. This scheme of reproduction, technically
known as alteniation of generations, occurs in a considerable
number of groups of both plants and animals. Another
exception is presented by the jNIendelian mode of heredity.
One of the most characteristic tilings about this kind of in-
heritance is the skipping of generations as regards heritable
attributes. When gray and white mice are mated the issue
are all like the gray parent ; but some of the grandchildren,
if inbreeding be followed, are like their white grandparent.
This departure from the rule of like is so important and
peculiar that some biologists have felt it necessary to frame
the definition of heredity so as to make it cover the appear-
ance in offspring of difference as well as of resemblance. In
truth though, if the term descent be understood to pass over
one or more generations, as in tlie case of Salpa, tlie rule
holds. Indeed, Mendelian inlieritance in hybrid races miglit
be described as a sort of alternation of generations.

Another aspect of the law of like must be noticed here.
Not only do organisms come from ancestors but we have
not a scrap of trustworthy evidence that they are or ever
have been produced by any other means. In other words,
the law of biogenesis, the law, that is, tliat negatives the
theory of spontaneous generation, is the same in large part
as the law that like produces like. So starting from any
given individual, problems of genesis and resemblance look
in two opposite directions, backward into the past, and for-
ward into the future. Viewing heredity from this standpoint
compels us to consider closely the degree of resemblance

Nature of Heredity and Problem of Mechanism 317

between descendants and ancestors. Full consideration of
the question may be deferred for the moment, though atten-
tion must be called to the fact that resemblance even of
tliis sort, never, so far as we know, amounts to identity, even
though in many instances it is wonderfully close. Difference
is a no less universal rule than is similarity and from this
it results that science is absolutely j)rohibited from attempt-
ing to minimize the importance of either truth. The prob-
lems of organic likeness and difference are inseparable, and
those biologists are so far right who contend that heredity
has to do with both. In the interest of clear thinking how-
ever, it is necessary to recognize that resemblance is one
fact and difference another ; and that the idea of heredity
has rightly grown up in connection with the former. Hered-
ity and variation are not simply one fact and one problem.
They are two distinct, though essentially interrelated and
wholly inseparable facts and problems. This way of put-
ting the matter seems unescapable when we consider a cir-
sumscribed group of organisms, as for example the horses,
in which much is known about the ancestry in geological time
and the species and varieties now existing. The student of
such groups is alert for both points of resemblance and
points of difference between the members of the group. He
knows that his scientific integrity depends on his preserving
an exact balance of effort towards the two kinds of charac-
ters, and the degree of resemblance is his sole criterion of
degree of kindred. Particular note should be taken of the
difference of starting point relative to problems of heredity
held by students of genetics and by students of natural
organic groups. For the former the descent aspect of the
definition we have adopted is observationally known and is
the part in which their main interest lies, while for the
latter the genetic connection is, in a vast majority of cases,
forever beyond the reach of observation. With him it has
to be inferred or ignored. But what is his basis for in-

318 The Unity of the Organism

fcrence? Degree of resemblance and that alone, bo the
comprehensive and balanced study of resemblances-and-
difFerences is far more important with the student of organic
groups than with the geneticist. The former must perforce
devote himself to resemblances more broadly and more deeply
than does the geneticist, and so is sure to have an ampler
mass of facts at his command.

Looking at the phenomenon of heredity from the vantage
point now reached, a fact that cannot escape attention is
that the infinite number and kind of resemblances presented
by the living world co-exist with a likewise infinite number of
differences. This fact brings us to where we can state sharp-
ly the problem now before us : If the resemblances among
completed individual organisms are explained, as prevalent
theory holds them to be, by referring them to the chromo-
somes which constitute only a small fraction of the total
mass of organisms, and which have little observable variety
as compared with tliat among organisms, how have all the
differences among tlic organisms come about? Of the vast
total mass of material that enters into the make-up of living
nature and which is composed of chromosomes plus whatever
else the living body contains, how has the relatively small
mass of relatively undifferentiated chromatin produced the
great mass of relatively highly differentiated cytoplasm en-
tering Into the tissues and organs?

It should be stated at the outset that so utterly insignif-
icant Is the positive evidence of the production of c3'toplasm
by the chromosomes as compared with the evidence of the
fundamental coexistence and cointeraction of these sub-
stances, that very few biologists are so bold as to contend
that either ontogenetlcally or phvlogenetlcall}^ are chromo-
somes literally first, and producers of other parts. The
extreme form of the germ-plasm theory probably implied
tills, althougli Weismann never followed the logical conse-
quences of his speculations into phylogcnetic history.

Nature of Hcrcditjj and Problem of Mechanism 319

E. A. Minchin, as previously noted, lias taken the bull
by the horns in his address on The Ez*olutio7i of the Cell and
contended that the ehromosonies or their immediate ances-
tors, chromatic granules, were the primal organisms. Min-
chin's ideas deserve examining as an exam])le of where
elementalist speculation may lead even at this late day of
supposed fidehty to objective evidence. Minchin accepts the
classification of biologists made by a poet writing for Punch
into "cytoplasmists" and "chromatinists" and declares him-
self a "whole-hearted chromatinist." "All the results," he
says, "of modern investigations into the structure, physiol-
ogy, and behavior of cells on the one hand, and of the
various types of organisms grouped under the Protista, on~
the other, . . . appear to me to indicate that the chromatin-
elements represent the primary and original living units or
individuals, and that the cytoplasm represents a secondary
})roduct." '* These "hypothetical primitive organisms" Min-
chin thought might well be called hiococci, the name used
by Mereschkowsky for certain primal beings imagined by
him. The author's desire to keep in sight, at least, of objec-
tive reality is obvious, and leads him to sa}' frankly, "We
have as yet no evidence of the existence of biococci at the
present time as free-living organisms." ^ How this admis-
sion fits in with the statement previously quoted about all
the results of modern investigations, he appears not to have
felt it necessary t« consider. Nor did he neglect to dwell
upon the similarity between these chromatin-elements, with
their continuity through simple division, and the germ-plasm.
This aspect of the subject appealed to him especially, and
some of his terminology is highly characteristic of the ele-
mentalist standpoint and especially instructive for the pres-
ent discussion. The conception which has become familiar
to us in late years that the germ-cells of the metazoa "throw
off, as it were," a soma, has a prominent place in Minchin's
comparison of the germ-plasm of multicellular organisms

320 The Unity of the Organism

with the chromatin-clements of the Protista.

One of the most significant things about this particular
development of chromosomal elementalism is its relation to
the plasmic elementalism as first set forth by Dujardin, and
later by Haeckel in his Moneron theory. An essential aim of
the last mentioned theory was to reduce "life" to an ultimate
simplicity in the sense of conceiving it as once manifesting
itself without organized substance — in "organless organ-
isms," as Haeckel liked to express it. Minchin criticizes with
due severity the "phantom" Moneron which has been "per-
mitted to masquerade for many years under the false appear-
ance of an objective phenomenon of Nature." ^ But cu-
riously, he appears not to have noticed that so far as objec-
tivity and logic are concerned his proposal is merely to
displace the phantom Moneron by the phantom Biococcus.
The question of structurelessness versus organization is no
less pressing in the one case than in the other, as indeed
Minchin's own statement shows. "The earliest forms of
life were 'Biococci,' minute ultramicroscopic particles of
mycoplasm, without organization," he says in presenting
Mereschkowsky's theory. ^^

A theory of chromatin hegemony less startling than this
by Minchin, but hardly more satisfactory when viewed in the
full light of fact and logic, has recently been elaborated by
H. F. Osborn. Osborn's theory does not, he thinks, require
him to conceive chromatin to be actually the primal organic
substance. It is more probable, he holds, that "chromatin
and protoplasm are coexistent in cells from the earliest
known stages." ^^ But the author's central purpose, that
of working toward "an energy conception of Evolution
and an energy conception of Heredity and away from
the matter and form conceptions which have prevailed
for over a century," ^- permits him to pass over rather
lightly the morphology of the hypothetical first Life. It is
clear, though, that *'heredity-chromatin,'^ a term which he

Nature of Heredity and Problem of Mechanism 321

uses as a synonym for germ-plasm, holds a commanding
place in his mind. This is clear from many direct state-
ments, as for example that of the conception tliat chromatin
is the ^'seat of heredity," while protoplasm is the ^^expres-
sion*' of it.^'*^ But a "seat" as thus used is always some-
thing far more fundamental and interesting than an "expres-
sion." For instance, in Osborn's enterprise the "matter and
forai" which, as indicated above, he proposes to move away
from, would come under the head of "expression" rather
than "seat." There are several highly significant things
about these speculations, only one of which is it justifiable
to mention here. That is the curious dualism into which
Osborn is led. As between Body- and Heredity-chromatin,
he conceives a sort of independence which reminds one of the
independence of Body and Mind assumed by the hypothesis
of psycho-physical parallelism. His theory of heteroplasy
conceives that "we are studying not one but four simul-
taneous evolutions." ^* Of these four one is the Inorganic
Environment and another the Life Environment. That is,
two pertain to the Environment, so that the other two per-
tain to what in ordinary biology is considered the organism.
But in Osborn's theory the "developing organism (proto-
plasm and body-chromatin)" is only one of the two evolu-
tions, the other being "heredity-chromatin." In other words,
so far as evolution is concerned, the organism is one thing,
having its laws of evolution which are pretty well known,
while the heredity-chromatin is quite another thing, the evo-
lutionary laws of which are still to be discovered.

This wiU suffice to indicate how uniquely dominant a role
chromatin, or the heredity variety of it, plays in this sig-
nificant speculation. A direct examination of it is not
necessary, since our whole argument will be recognized as
incompatible with it. We may, however, call attention to
the unmistakable indications scattered through the theoreti-
cal part of The Origin and Evolution of Life that so far

322 The Unity of the Organism

as chromatin enters into his theory the author is faced
toward metaphysics, and metaphysics of a distinctly mysti-
cal cast. One of the moderate expressions showing this trend
occurs on the first page of the preface: "Some of these
miracles [of adaptation] are recited in the second part of
this volume to show that the geran evolution is the most
incomprehensible phenomenon which has yet been discovered
in the universe." The author's emotional attitude toward
his theory is to me one of the most significant things about
the book. And my criticisms of the theory, implied rather
than expressed, are not at all against the fact that an emo-
tional attitude is displayed by the author but only that the
focal point of this attitude should be chromatin, whether
heredity-chromatin or any other — especially when the au-
thor is a palaeontologist !

Meaning and Criterion of ^^ Mechanism of Heredity"

If we decide to apply the term "mechanism" to the means
by which organisms produce other organisms like themselves,
we obviously ought to consider carefully what a mechanism
would be that could serve such a purpose. Obviously, I say,
such a consideration is due because nowhere else in the world,
either the natural or the artificial world, do we find need for
any such mechanism. Heredity is surely one of the most
distinctive phenomena presented by living beings, so its
mechanism must be unique. We have already called atten-
tion to the familiar but often ignored fact that "heredity"
is the term applied to the universal truth that as the or-
ganism unfolds itself from the relatively minute and simple
stage known as the germ into the relatively large and com-
plex stage known as the adult, it does this in accordance
with a scheme or pattern characteristic of the species to
which the organism belongs, so that any particular individual
in the series resembles those which have gone before it.
And this unfolding, we have pointed out, consists essentially

Nature of Heredity and Problem of Mechanism 323

of a great intricacy and succession of transformations. From
this it follows that the "mechanism of heredity" would be the
materials and structures by which these transformations are
accomplished. To think of the hereditary substance, or the
"mechanism of heredity" as belonging to the germ-cells alone
is utterly unwarranted by the obvious facts, as everybody
must see who will reflect broadly and candidly on the sub-
ject.

A truly objective study, consequently, of the mechanism
of heredity must be a study not only of the materials and
structures in the germ-cell stages, but in all stages what-
ever, by which the production of hereditary parts and attri-
butes is accomplished.

In other words, a real study of biotic genesis, whether
the generating parts be hereditary or variational, that is,
like or unlike those of ancestors, must be first and essentially
by the methods of descriptive ontogenesis. The only direct
evidence we have or can have of the origin of a part or an
organ is the observed transformations by w^hich that part
or organ is produced from preceding parts, and the mate-
rials participating in the transformations are the hereditary
substances, if that term is to have any legitimate meaning.

To illustrate: the lens of the vertebrate eye originates
from a patch of ectoderm exterior to the optic globe. The
optic globe itself arises by an outpocketing of the primitive
brain. Since both lens and globe resemble the corresponding
parts of the eye of ancestors near and remote, their develop-
ment comes under the principle of heredity ; and the ecto-
dermal patch giving rise to the lens, and the part of the
primitive brain giving rise to the optic globe are mechanisms
of heredity ; and the whole observable series of embryonic
parts which culminate in the completed eye are the only
direct evidence for the mechanism of heredity for the eye.
So is it with all biotic ontogenesis whatever. This brief
statement is in essence nothing more than the gist of the

324 The Unity of the Organism

facts discovered and principles laid down by Wolff and von
Baer, and the truth expressed has been the foundation of
all solid achievement in enibryolof^y throughout the history
of the science. It is strange that conditions should arise
at this time of advanced progress in biology which involve
what seems decidedly like an abandonment of this founda-
tion.

It could hardly have been believed in the hey-day of
descriptive embryology, in the decade, for instance, follow-
ing the publication of Francis Balfour's "Comparative Em-
bryology" that the time would again come when the domi-
nant theories of organic genesis would have regard to the
completed organism at one end of the series, and the germ-
inal elements at the other, with well-nigh complete neglect
of all the intervening stages. Yet this is essentially what
has happened. One cannot avoid seeing this if he examines
with open mind almost any of the literature produced by
the modern school of geneticists, especially if the work has
been under the spell of Mendelism accepted as a creed to
which conformity must be reached by hook or crook, and not
as an instrument to be used when applicable and useful.
Unless observation is to be denied a primary place in bio-
logical method, and unless that place can be unreservedly
given over to inference and deduction, I see no escape from
the necessity of testing by the familiar methods of embryol-
ogy the hypothesis that chromosomes or any other particu-
lar bodies are the mechanism of heredity ; that is, of showing
in what particular way the bodies participate in the origin
of a given part or organ from its forerunners in the develop-
mental series : If, for example, it be contended that a par-
ticular portion of a chromosome causally explains eye color,
then some activity or transformation, morphological or
chemical, of that chromosome, not away back in the germ-
cell, but in the cells of the part from which the color-bearing
cells immediately arise, should be proved. This alone would

Nature of Heredity and Problem of Mechanism 3^5

be direct evidence for the chromosoiiial hypothesis of
heredity.

And thus it comes to pass that evidence on the problem
of the mechanism of heredity will be of two sorts, direct and
indirect. Direct evidence will be that obtained by immediate
observation of the actual transformation of substances and
parts into other substances and parts known to be heredi-
tary. The methods here will be those of ordinary histo-
genesis and organogenesis, only carried on witii reference
to the hereditariness of the parts produced. Indirect evi-
dence, on the other hand, will be any sort of evidence which
does not come from immediate observation as above indi-
cated, but depends upon some measure of inference inter-
posed between the observation and the conclusion. By far
the greater part of the evidence of this kind being used at
present in researches on heredity comes from observations
on the germ-cell stages at one end and on adult stages at the
other end, of the ontogenetic series. From these observa-
tions the inference is drawn by various courses of reasoning
that the obsei'ved adult structures and attributes are de-
pendent upon and explained by the observed germ-cell sti-uc-
tures and attributes.

Our next task will be that of examining both these sorts
of evidence with special reference to the problem of heredi-
tary substance as it presents itself in present-day genetic
research, namely that of whether nuclear substances, espe-
cially chromatin, or cytoplasmic substances, are the
"mechanism of heredity."

REFERENCE INDEX

1. Conklin ('15) 103 8. Minchin ('15) 454

2. Thomson 27 9. Minchin ('15) 446

3. Thomson 37 10. Minchin ('15) 449

4. Pearl 35 11. Oshorn 92

5. Pearl 3 12. Osborn vii

6. Castle 6 13. Osborn 93

7. Minchin ('15) 450 14. Osborn 21

Chapter XII

EVIDENCE FAVORABLE TO CHROMATIN AS
"HEREDITARY SUBSTANCE"

A. DIRECT EVIDENCE

Evidence from the Ontogeny of Some Protozoans

WE conform to the time-honored custom in zoology of
beginning tlie examination at tlie lower end of the
taxonomic scale.

As a first example we take the trichocysts {tr. figurel5)
that occur in some protozoa of the class Ciliata. Parame-
cium, for instance, is well armed with these organs. Briefly
characterized, they are elongated, spindle-shaped bodies sit-
uated in the ectoplasm perpendicular to the surface of the
body. Each has a short bristle-like process at its outer end
which probably pierces the pellicula, or outermost layer of
the body, and is in contact with the surrounding world.
They are organs of offense and defense, and under proper
stimulation are explosively converted into long, somewhat
rigid threads which project from the surface of the animd,!.
As the animal on which the investigation we shall make
use of is not Paramecium, but a less generally known rela-
tive, Frontoina leucas, our figures will be taken from tliis
latter species (figure 15). The work referred to is by C.
Tonniges and is so recent as to have had hardly time to
receive the confirmation by other students whicli unexpected
results should generally get before being used in a work
like this. But Tonniges is an experienced and trustworthy

326

Chromntin as ''Hereditary Subfita/nce''

327

worker; and since there is nothing inherently improbable in
the results, it seems justifiable to take them as conclusive,
at least in main outline. The observations on the develop-

m.

mac r. -^

^

i3»r ^--■■iM»S' villf^y ^

rrJ^-'

— -*^'<^ .••^>Si:.!:V.--= ::...•. ■. '..■■. •■.■•.!\ •/■.•.■.■•^••.'.;x-:->

;->ic;:.!:.y.-

FTOURT; 15. FROXTOXTA T.EUCAS ( AFTER TOXXTGEs).

c, cilia. Corp., cortical plasma, end., endoplasm. fd., food, macr.,
macromicleiis. micr., micronucleus. tr., trichocysts. trcli., tricho-
chroniidia.

ment of the trichocysts that specially concern us now may
be stated in a short paragraph.

The organs (trch. figure 15) originate in the macronu-
cleus {macr.) and migrate through the nuclear membrane

328 The Unity of the Organism

and cytoplasm of the animal's body to their final position
in the ectoplasm. An essential constituent of the germ, as it
may be properly called, of each trichocyst, is a body which
from its familiar characteristics as to density, light refrac-
tion and stainableness, Tonniges does not hesitate to regard
as chromatin. It seems undoubted, consequently, that chro-
matin of the macronucleus contributes directly to the origin
of the trichocysts in Frontonia and probably in all related
protozoans. Figure 15 shows the germinal bodies, trch, in
the macronucleus, macr. and various stages and positions of
the trichocysts as they develop and make their way through
the cytoplasm. The details of development are highly in-
teresting and will be examined more closely in a later sec-
tion. The very brief account given here suffices to show
chromatin acting directly as "hereditary substance" in the
production of trichocysts. But, as we shall see later, while
chromatin is here an undoubted physical basis of heredity,
it is not the only substance that plays such a part in this
particular case. Nor should the reader neglect to notice
that the chromatin functioning thus belongs to the macronu-
cleus which, according to current interpretation, is not con-
cerned with reproduction but with nutrition, its chromatin
being called "vegetative."

Perhaps the clearest cases among the protozoa of direct
contribution of the nucleus to the production of organs are
furnished by the origin of the flagella in some groups. A
good example is furnished by the soil amoeba Naegleria gru-
beri upon which Professor Kofoid has recently published a
short paper (figure 16a, 16b, 16c, 16d). Individuals of this
species change "on slight provocation under conditions of
laboratory culture," from an amoeboid, non-flagellate phase
(figure 16a) to a non-amoeboid flagellate phase (figure
16d). The nucleus of the animal is in the form of a single
karyosome situated within a heavy nuclear membrane. (Fig-
ure 16a). Professor Kofoid's description of the develop-

Chromatin as ''Hereditary Substance^''

3^9

mcnt of the flagella is clear. He says : "When it enflagellates
the karyosome sends out a chromatic process (Figure 16a)
which traverses the nuclear membrane, forms a marginal

bp.--p-^-...iii^-^%^->^

B

FIGUHE 16. XAEGLERIA GRUBERI ( AFTER KOFOId).

bp., blepharoplast. ky., karyosome. n., nucleus.

blepharoplast (Figure 16b hp.) and emerges as two long
flagella. (Figure 16d). The body assumes a rigid, asym-
metrically curved shape and the organism swims away in the
typical spiral course." ^ Since the regularly recurring flag-
ella of this animal, two in number, constitute a resemblance

330 The Unity of the Organism

between the corresponding stages in the life of each individ-
ual, and undoubtedly between an individual and its progeny,
they are an instance of heredity ; and since their development
is directly contributed to by the chromatic body of the
nucleus, we have here a clear instance of chromatin acting
as a mechanism of heredity.

The reader will recall that in Crithidia leptocoridis and
in Giardia muris, two protozoans quite different from each
other and both very different from the amoeba-like creature
just described, the flagella of the adults are also connected,
by way of a blepharoplast, with the central chromatic body
of the nucleus. The same connection is known to occur in
numerous other protozoans. Indeed, its occurrence is so
frequent that some authorities now regard flagella in gen-
eral as belonging to the nuclear system. Minchin particu-
larly is a supporter of this view. Starting from species like
Mastigvna setosa in which Goldschmidt has shown that the \
flagellum seems to arise directly from the nucleus, Minchin
presents a scheme of "possible phylogenetic origin of the
different types of flagellar attachment in flagellates."

An important element in the general problem of the rela-
tion of flagella and cilia to nuclei is the question of the
origin and nature of the blepharoplast. The statement was
made when we were examining the adult anatomy of Giardia
muris that the blepharojDlast question would receive further
consideration in the discussion now occupying us. This
question is fundamentally connected with a cell organ which,
though of undoubtedly high importance, has not hitherto
figured in our treatment. Reference is made to the centro-
some.

The term "blepharoplast" (from the Greek hlepharon, eyelash)
came into biology from the botanical side. It was apphed by
Webber to a body occurring in the sperniatogcnous cells of •
Ginh'ffo and Zamia, "because of their special function as cilia-
fornurs/' the spermatozoids being derived from the body in

Chromatin as ''Hereditary Substance'' 331

these plants. That tlie production of cilia is the main if not
the exclusive office of the body in these and other plants, Web-
ber and other observers have made certain. The question of
the relation of this body to the centrosome, which latter is gen-
erally held to be part of the nuclear-divisional apparatus of the
cell_, has been much discussed. In the })lants mentioned Web-
ber believed, seemingly with full justification, that the blepharo-
plast arises de novo in the cytoplasm and at no time has con-
nection with any part of the division apparatus. It seems to
have no office other than that of producing the cilia. Almost
certain it is_, consequently, that in several distinct groups of
plants, Ginkgo, cycads and mosses for example, the main por-
tion of the motile organ of the sperm cell is derived from the
cytoplasm of the cell and not from chromatin or any other
nuclear material.

But such an origin does not hold for the corresponding organ
of all sperm cells. In several animals, insects and salamanders
for example, there is practical agreement among authorities that
the axial filament of the sperm "tail" grows out from the
centrosome.- Furthermore, it seems to be accepted that in
some animals, e.g., some echinoderms and worms, the centro-
some arises from the nucleus.^ Viewing these facts in connec-
tion with the recent tendency to exalt the nucleus as the "seat"
of all sorts of cell capacity, and putting them alongside those
above sketched concerning the nuclear connection of flagella in
some cilia-bearing protozoans, one readily sees the strong temp-
tation to homologize the motor aj^paratus of the spermatozoan
with that of the protozoan and conceive a common basis for both
in the nucleus. If the centrosome could be held to have arisen,
phylogenetically, from nuclear chromatin; and if the blepharo-
plast, which is unquestionably a cilia-producer, could be counted
as fundamentally a centrosomal structure; and could such a
generalization be establislied, it w^ould certainly be a considerable
achievement in support of the theory of universal nuclear and
chromatinic hegemony in development. AVe must, consequently,
scrutinize somewhat closelj^ the evidence which points in this
direction.

Ez^ideiice from Certain Cells of Midti cellular Organisms

A decade ago the centrosome problem held a commanding
place in cytological investigation and an extensive litera-

B32 The Unity of the Organism

ture gathered around it. Nothing like an exhaustive review
of the observations and hypotheses can be thought of here.
But our present interest in it, namely the question of whether
or not flagella are originally and fundamentally part of the
nuclear system, requires us to acquaint ourselves with some
of the main results reached by investigations into the struc-
ture, function and origin of the centrosome.

As regards structure, what most concerns us is whether the
minute central granule, deeply stainable in certain special dyes,
is the essential thing, and so sliould be regarded as the centro-
some, or wliether this granule, togetlier with tlic more volumi-
nous, less dense, less easily stainable substance around it, are
fundamental so that the whole should be regarded as the cen-
trosome. Such an examination of the writings on this question
as a general student is able to make almost forces him to con-
clude that the application of the names centriole, micro-centrum,
cytocentrum, astrosphere, attraction sphere, etc., to the various
objects treated under the general designation "cellular cen-
ters," is at present largely a matter of personal choice. This
results from the great structural variety, taking the whole ani-
mal kingdom together, of the parts dealt w^ith, and the meager-
ness of positive knowledge as to the functions of these parts.
Thus, on the question which cliiefly concerns us now, that of
what shall be called centrosome, great difference of view and
hence of nomenclatural usage prevails.

The term centrosome was first used according to Wilson, by
Boveri and was applied to a small protoplasmic spherule differen-
tiated from the surrounding cytoplasm "in the center of which one
or two exceedingly minute spheres, the centrioles, are enclosed." ^
In a word, as originally conceived, the centrosome conformed to
the second alternative indicated in what was said above about what
a centrosome really is. But later investigations produced facts,
chiefly concerning the penetration of the astral rays during in-
direct cell division into the less stainable substance around tlie
central granule tliat led many investigators to regard tlie granule
alone as the centrosome. Tliis is the position held by E. B. Wil-
son in the 1899 edition of The Cell and also by O. Hertwig in
his Alloemeine Bi()lo<fie. But Hertwig tells us in the fourth
edition (1912) of his book ^'' that the arguments ])roduced by
Heidenhain in Plasma und Zelle have convinced him that the

Chromatin as "Hereditarjj Substance** 333

term centrosome oujrlit to be used in the original sense, tlie name
centriole, used by Heidcnliain and others for the central granule,
being favored by Hertwig.

Heidenliain's statement tliat the centrosome problem has re-
cently entered a new stage, largely, according to him, through
the researches of Vejdovsky and Mrazek, seems justified by the
observations. "Evidentlv," savs Heidenhain, "in the eentrosomes
of large cells (eggs, blastomeres,) we have to do not with any
sort of sharply differentiated bodies of definite organization, not
with organs wl^ose eaj)al)ility rests upon a definite, intrinsic con-
stitution readied througli systematic development, but with struc-
iiiral material transported from place to place through the ac-
tivity of the radially differentiated cell substance and heaped up
for further use." ^

One can hardly avoid reflecting that this statement by Heid-
enhain seems to accord much better with the physical-chemistry
conception of the cell, that is. with that of the cell as a system
of phases in dynamic equilibrium, than with the older idea of the
centrosome as in some peculiar way a "dynamic center" of the
cell. Nevertheless for the purpose of a general discussion like
that in which we are engaged, we may leave the question of what
the term centrosome ought to be applied to undecided, and fix
attention upon the central granule as belonging structurally to
the "cellular center," this phrase being understood to cover a
very wide range of objects none of which are simple and some
of which are quite complex.

As to the function of these "centers" there appears to be
unanimitv among the authorities that thev are in some way
"dynamic centers of the cell" as originally expressed by Boveri.
There is some satisfaction in this unanimity even though the
range of possibilitv in "dynamic" is Jio wide as to make the
unanimity rather indefinite. For one thing, it is certain that
the centers take an active and important part in indirect cell
division. This is a basal tenet of modern teachings concerning
cell division. The role of the centers as force- and activity-
producers which concerns us here is in connection with flagella
and movements characteristic of these organs.

Evidence from the Spermatozoan.

There appears to be nearly complete agreement among
authorities that the axial filament of the tail of the sperma-

334? The Unity of the Organism

tozoa of many animals arises from a basal granule or cen-
triole of the spermatid. Illustrations of this may be seen
in many of the recent studies of spermatogenesis. If one
compares early stages of the transformation of the sper-
matid into the spermatozoan, like those of the rat (figure
17) with some of Miss jMcCulloch's figure (8) of
Crithidia, already described, the resemblance between the
two is unmistakable, when one considers the difference in
the animal species to which each belongs. In both there is
the relatively voluminous cytoplasm, the large nucleus (7^^^c.),

nuc,-

FIGURE 17. SPER31ATID Or THE RAT (AFTER DUESBERG).

a.f., axial filament, c, centrosonie. nuc, nucleus.

the filament («./.) connected with the granule (has. gr.),
and between this granule and the nucleus another chromatic
body (c). To be sure the resemblance falls far short of
identity ; but it is nevertheless so striking that hardly any
one can avoid recognising it, nor can he well avoid asking
what it means. Can it be a resemblance due to descent and
hence an instance of heredity.^ That it is due to descent
in the meaning of the term as used in our definition of hered-
ity is certainly not the case. Descent in that definition
means observed descent as when the ancestry of a child
is a matter of family record. Such resemblance is declared
due to descent because the ancestry is known on other
grounds than that of such resemblance as appears be-
tween the adult unicellular Crithidia and the developing

Chromatin as ^'Hereditary Substance^' 335

sperm cell of the rat. The only ground for supposing de-
scent in the latter case is the resemblance itself. We have,
consequently, no right to reason about the correspontHng
parts of these two organisms as though we had other })roof
of their kinship than that of the resemblance indicated.

Similar needs and activities and surrounding conditions
tend to make organisms resemble one another. No biological
principle is better established than this. And surely as be-
tween Crithidia and a rat sperm there is much similarity of
need, of activity, and of environment. Both are single cells
of approximately equal size, and in botli a high degree of
locomotor ability adapted to a fluid or semi-fluid environ-
ment is essential ; so we are bound to recognize on purely
anatomical and physiological grounds and quite apart from
descent in any strict sense, that considerable resemblance
between the two might be anticipated. In other words, tlie
well-known and widely operative fact of parallel adaptive
modification in development is at least as likely to be the
explanation of the resemblance here as is descent.

Appeals to recent cytological discoveries for evidence to
support the theory of genn-plasm continuity as the basis
of heredity have been altogether too unmindful of this bio-
logic principle of adaptive parallelism. With such a fact
before us, as for example that of the "practical identity" in
minute structure of the heart muscle of the horse-shoe crab
and of vertebrates ^ where there is hardly a glimmer of
probability that the resemblance is due to anything else
than adaptive parallelism, how escape recognizing that the
resemblance between a protozoan and a vertebrate sperm-
cell is probably due to the same cause? And innumerable
instances hardly less striking than this presented by the
hearts of Limulus and vertebrates could be pointed out.

Origin of the flagellum from the chromatin of the nucleus
in any or many protozoans has little weight as proof that
the axial filament of the spermatozoan is phylogenetically

336

The Unity of the Organism

of the same origin. While, as stated above, it may be ac-
cepted as proved that in some animals the centrosome arises
from the nucleus, in a far larger number of animals the

^c-

rxxic.

FIGURE 18. SPERMATID OF SALAMANDER (afTER HEIDENHAIX).

a.f., axial filament, c, centrosome. nuc, nucleus.

evidence is all against such an origin. Furthermore, in many
animals a pair of "cromioles" occur, seemingly homologous
to the chromosomes, situated in the cytoplasm of various

FIGURE 19. SPERMATID OF SNAIL (aFTER HEIDENHAIn).

cells at a point as remote as possible from tlie nucleus ; and
from one of these in the sperm mother cell the axial filament
of the spermatozoan grows out.

The development of the spermatozoan from the spermatid
in two widely separated animals, a salamander (figure 18,
a and b) and a land snail (figure 19)^ illustrates several
interesting aspects of the point before us. In both the sper-

V

Chromatm as ^"Hereditary Substance^* 337

matid possesses a . lasli or flagelluin wliich arises from the
outermost of a ]5air of <rranules or centrioles situated in the
cytoi)]asm just beneath the surfaee of tlie celL In an early
stage of the transformation of the salamander spermatid the
pair of centrioles moves inward toward the nucleus, the inner
member of the pair finall\' entering the nucleus and becoming
the middle piece of the sperm head, while the outer membrane
is converted into a ring which finally contributes the undulating
membrane of the tail of the completed sperm.

Connection between the centrioles and nucleus in the snail's
sperm is accomplished in a different manner. Instead of an
inward migration of the pair as in the salamander, the inner
member of the pair sends an ingrowth toward the nucleus, the
centrioles themselves remaining at the surface of the cell and
remote from the nucleus. This ingrowth becomes much elon-
gated and produces finally the axial thread of the sperm, the
anterior end of which is embedded in the nuclear part of the
head. Much this same sort of thing occurs in many other
animals, both vertebrate and invertebrate.

There can be no question then that in a large number
of animals the centriole of the sperm is primarily quite inde-
pendent of the nucleus, and only becomes connected with it
as the sperm develops. Consequently, to speculate that orig-
inally or ancestrally the nucleus gave rise to the centriole
and axial thread of the sperm is to go exactly contrary to
the most direct and positive evidence we have bearing
on the question. To this direct evidence drawn from the
study of spermatogenesis, that the centriole is in its origin
quite independent of the nucleus, should be added the ex-
tensive evidence that the centriole is self-propagating by
division and passes on from cell generation to cell generation
somewhat as the nucleus does. But this fact is so familiar
a part of elementary cytology as to need no special treat-
ment.

The upshot of this discussion is that while as regards
flagella in some protozoa there is solid observational gi'ound
on which to rest the theory that chromatic bodies of the

338 The Unity of the Organism

nucleus are "bearers of heredity", the effort to make the
facts presented by the protozoans support the general theory
of chromatin as the "hereditary substance" by comparing
the nucleus-blepharoplast-axial filament of the spermato-
zoan, is quite unwarranted. Indeed, due regard to all the
facts involved in this comparison finds in them very strong
evidence against the conception that chromatin is the exclu-
sive "hereditary substance."

Evidence from Pigment Cells

Another set of facts brought out by recent studies which
connect the nucleus directly with the production of definite
hereditary attributes, concerns the ontogenetic origin of
certain colors. A paper on an investigation in this field
published in 1915 is introduced by this sentence: "The more
recent work on the formation of melanin seeks to derive this
pigment from chromatin elements".^ One may remark the
form of expression here. Recent work "seeks to derive"
melanin from chromatin, rather than "seeks to learn whether,
if at all, and in how far melanin is produced from chroma-
tin". No biologist speaking as a proponent of the "scientific
spirit" will, I think, hesitate to admit that the latter mode
of stating the problem is more in accord with that spirit.
Yet when a specific situation arises, the tendency to depart
from the seeking-to-learn spirit and to assume that of seek-
ing confirmation for an adopted hypothesis is still well-nigh
irresistible even in science. The temper of the day in a
considerable section of biology is one of thorougli going
partisanship in behalf of chromatin.

The "seeking to derive" things from the cliromosomes is
not by any means limited to melanin. Neurofibrils, muscle
fibrils, and glandular secretions are among the things which
so far have appeared as conspicuous claimants for such an
origin. And one familiar with tlie discussions of ontogenesis
in tlic ])eriod of the Gastrea theory, can hardly fail to recog-

Chromatin as ^'Hereditary Substance'' 339

iiize the same tendency that prevailed then to force the
evidence. Forecasting' in tlie light of history alone, we may
anticipate that out of the chromosome theory of heredity
will emerge proof that these bodies are of great importance
in actual development, but that their importance consists in
their being indispensable tools or agents of the organism
rather than entities, ultimate and supreme in their power
over the organism. Thus already the demonstration is al-
most if not quite complete that the nucleus plays an im-
portant part in the production of melanin and other organic
pigments, and so is a mechanism of heredity to some extent,
so far as colors are characteristic in genetically related or-
ganisms.

A notable forward step toward solving the problem of
pigment formation was taken by E. IMeirowsky. Besides
producing important evidence bearing on the old and much
discussed question of whether pigment arises in the epi-
demiis or cutis or in both, jNIeirowsky turns his attention
to how the melanin arises witliin the cells. He concludes that
it is the result of the transformation of a colorless substance
originating in the nucleus. From the intense red it assumes
when treated with the basic stain pyronin, this substance is
called by the author pyrenoid nuclear svibstance. It is said
to pass through the nuclear membrane into the cytoplasm.
The particles gradually turn brown, this color appearing
first on their surfaces. The transformation of color is said
to begin in some of the substance before it leaves the nucleus.
It is not contended that the pyrenoid substance is derived
from the chromatin of the nucleus, but merely that it arises
in and is extruded from the nucleus.

The latest contribution to this subject which has come to
my notice is by Davenport Hooker. Studying the develop-
ment of pigment in various tissues of the embryo of a frog,
Rana pipiens, this observer has shown conclusively that the
melanin granules all arise in the cytoplasm at its line of

340 The Unity of the Organism

contact Avitli tlie nucleus. The first pigmentation ap])ears
in a very thin layer over the whole outer surface of tlie
nuclear membrane. From here it increases uniformly all
around the nucleus and gradually fills the entire cytoplasmic
part of the cell, the nucleus itself, however, remaining free
from pigment. The absence of pigment from the nucleus
of pigmented cells is, as is well known, of wide occurrence.
In this case at least the evidence seems conclusive, as the
author says, "that the nucleus plays an essential part in
pigment formation".^ What that part may be is the im-
portant question, and one as yet by no means fully answered.

Several investigators hold that the chromatin of the nu-
cleus is the direct source of the })igment. Thus, for example,
Aurel von Szily reports that in the vertebrate eye the me-
lanin granules are produced from the colorless rod-like bod-
ies derived directly from the chromatin of the nucleus. These
bodies he calls pigment bearers {Pigmenttrdger) }^ They
pass out of the nucleus through the nuclear membrane and
become disseminated through the cytoplasm, where they are
gradually transformed into melanin granules.

Much more evidence might be brought forward on the
moi*phological side that the nucleus at least and probably
its chromatin takes a direct part in the production of
brown pigment. And the supposition is strengthened and
extended by evidence produced in recent years of how, chem-
ically speaking, the nucleus does its work. The idea that the
nucleus is specifically concerned in the oxidative processes
of the cell had been gradually gaining definiteness for sev-
eral years before 1902, at which time R. S. Lillie produced
apparently conclusive evidence to this effect so far as con-
cerns frog tissues. He subjected living active cells to re-
agents which indicate oxidation in the animal body by change
of color.*

* Several such reagents are known but the one chiefly relied on by
LiUie and which has since been frequently used for the same purpose is

Chromatin as ^^ Hereditary Substance'' 341

Although some investigators report having failed to get
the differential reaction described by Lillie, on the whole his
evidence with much more of like })urport that might be cited,
makes the conclusion seem unescapable that for a consider-
able range of animals the "nucleus plays an essential part in
pigment formation by some activity wliich greatly resembles
an oxidizing- action."

How far tlie cliromosomes are responsible for this activity,
is by no means settled. Hooker could find nothing similar
to von Szily's "pigment bearers", or evidence of any kind
that the melanin granules come from chromatin. Indeed, he
brings forward a number of weighty considerations against
the theory that in the frog at least the chromatin is directly
concerned in pigment production. He holds that his obser-
vations demonstrate that in this animal "melanin is formed
in the cytoplasm of the cell at the point of known greatest
efficiency of the nucleus as an oxidizing agent."

Summarizing our examination of the direct evidence fa-
vorable to the theory of chromosomes, or at least chromatin,
as the mechanism of heredity, we fl7id that in the origin and
growth of flagella and pigment in some organisms the theory
receives a certain amount of support.

B. INDIRECT EVIDENCE

The indirect evidence favorable to the theory will now be
considered. Significantly enough the theory is supported
chiefly by this sort of evidence. To such an extent is this
true, and so sterling in quality and great in quantity is the

a mixture of one of the naphthols with a derivative of one of the ben-
zenes. This mixture produces a deep violet-colored fluid on oxidation.
By treating kidney tissue, for example, under 2:)roper conditions with
this indicator, Lillie found that the "nucleus of the tubule cells remains
comparatively clear and uncolored, and that the coloration of the cyto-
plasm is diffuse, but typicalli/ deeper in the immediate neiyhborliood of
the nucleus than elseichere — a clear indication that oxidations are espe-
cially active at the nuclear surface."

342 The Unity of the OrgamRm

evidence of this class, tliat many students devoting them-
selves exclusively to genetics seem not to realize that they
are dealing with such evidence. Reference is here made to
the truly brilliant researches of the last years proving be-
yond a doubt that in the sexual mode of propagation of
many plants and animals some sort of interdependence exists
between the attributes of tlie developed organism and the
chromosomes of the germ-cells.

Since it is taken as proved that such an interdependence
exists we are not required to examine criticall}'^ the evidence
itself. Rather are we to inquire concerning the nature and
meaning of that interdependence.

The Chromosomes of Germ-Cells in Fertilization

The field is one of magnitude and complexity, and we can
touch only its prominent landmarks. The earliest known
class of facts, as well as one of the weightiest, favorable to
the theory concerns the part played by the chromosomes
of tlie male and female germ-cells in fertilization, the struc-
ture and behavior of the male cells being especially impor-
tant. It is now an established fact that the head of the
male reproductive cell, the spermatozoan, consists mainly
of the transformed nucleus of the spermatid, that is, the
cell from which the sperm is immediately derived, and that by
far the larger mass of the liead comes from the chromosomes.
In fact, so demonstrably large a portion is thus derived that
the statement is made over and over again in recent dis-
cussions that the sperm head is "practically entirely" of
chromatin. And since this })art of the spermatozoan is
proved to be the predominant element in fertilization, and
since the offspring inherit from the father no less than from
the mother, the inference has been widely drawn and firmly
held that the chromosomes nuist be mainly, if not exclusively,
the "heredltar^^ substance". It is, however, generally admit-

Chromatin as *' Hereditary Suhstance^^ 343

ted tlicat in no case among animals, so far as known, is the
sperm head derived quite exclusively from the chromosomes.
A small amount of the cytoplasmic part of the spermatid
appears always to be carried on into the spermatozoan as
a surface layer of the head. And the "middle-piece" or
part immediately beliind the head, seems always to contain
material not derived from the chromosomes. We shall have
to examine these extra-chromatinic portions of the sperm
more fully when we undertake to find what substances,
whether in germ or somatic cells, participate directly in
actual development.

In the meantime we must recognize the important part
taken by the chromosomes, or more exactly by chromatin, in
fertilization and in the first steps of development of the
individual. The evidence is especially weighty in some of
the higher plants where according to one eminent botanist,
Eduard Strasburger, the nucleus only of the pollen- grain
enters the ovum. Summing up the results on the point,
Strasburger writes, "In these plants (the flowering plants)
the male sexual cells lose their cell-body in the pollen-tube
and the nucleus only — the sperm nucleus — reaches the egg.
The cytoplasm of the male sexual cell, is therefore not neces-
sary to ensure a transference of hereditary characters from
parent to offspring. I lay stress on the case of the Angio-
sperms because researches recently repeated with the help
of the latest methods failed to obtain different results." ^^
Should this statement receive confirmation by future investi-
gation it would mark the flowering plants as the group of
organisms in which specialization has gone farther than in
any other so far known toward making chromatin the sole
genetic intermediary between male parent and offspring.

But the sperm head, composed almost exclusively of chro-
matin, unites with chromatin only of the female germ-cell,
the quantity of the male chromatin being apparently equal
to that of the female chromatin. These facts are clearly very

344 The Unity of the Organism

weighty as evidence that chromatin plays a very important
part of some sort in heredity.

Fertilization of the Ova of One Species hy the Sperm of

Another Species

The class of facts next to be noticed as supporting the
chromosome theory of heredity has come to light through ex-
perimental researches, and concerns the cytological results
of fertilizing the eggs of one species with the sperm of
another. During the last fifteen ^^ears considerable work of
this sort has been done. Most of it has produced equivocal
results, but some of the positive results favor the chromo-
some theory, while others oppose it. At present we will
consider only those which favor it. Boveri, one of the most
intellectually resourceful and manually deft investigators in
this as in so many other aspects of cytology, writes : "The
Qgg protoplasm is with reference to these qualities [i.e., of
individual and species] only the material for the forma-
tive activity of the equally potent but opposite male and
female nuclear parts." ^^ Although this formulation was
made with special reference to Boveri's own observations,
as a matter of fact the evidence wliich seems to support
it most strongly has been produced not by Boveri but by
Curt Herbst. Herbst's most telling case is presented in
his Studies in Heredity. The evidence obtained "is
almost convincing, I think," says Morgan, "in favor of
the view that chromosomes are the essential bearers of
the hereditary qualities." ^^

Herbst conceived the interesting experiment of giving
spermatozoa a chance at eggs which had already received
the impulse to develop without the intervention of sperm,
that is, parthenogenetically.^^ By using the eggs of one
species and the spemi of another, he thought he might be
able to recognize the difference in effect of the female and

Chromatin as '^' Hereditary Substance^'' 345

the male chromosomes, should development ensue under the
impetus of both artificial parthenogenesis and artificial fer-
tilization. The animals used were species of two genera of
sea-urchin Spliaer echinus and Strongylocentrotus, tlie eggs
being from the first and the sperm from the second. A few
minutes after the impetus to parthenogenetic development
had been given by treating them with a weak solution of
valerianic acid, the eggs were removed to normal sea water
and mingled with the sperm of Strongylocentrotus. The
sperm fertilized some of the eggs, but since the nuclear
changes of the male nucleus within the egg always lagged a
little behind the changes of the female nucleus, it happened in
some instances that the male nuclei passed into one only of
the two first blastomeres, the result being that in the em-
bryos in the two-cell stage, one cell contained only a female
nucleus, while the other contained both a female and a male
nucleus, which in some cases fused in the usual fashion mak-
ing a larger nucleus than that of the other cell. This could
be made out by direct observation. It was further obsei*\ed
that in batches of eggs where a two-cell stage of this sort
occurred, the resulting larva possessed a typical hybrid
skeleton on one side, and a skeleton typical in several respects
of Sphaerechinus on the other.

"The female skeletal side," says Herbst, "corresponds to
the small nucleus designated as left, and tlie hybrid to tlie
large one designated as right." Although no details are
given as to the exact relation of the two kinds of nuclei to
the skeletal elements presenting characters from two diverse
species, the inference is hardly to be escaped that the rela-
tion is one of actual causal dependence. But Herbst's atti-
tude of caution and restraint must not be ignored, as it
seems to have been by some of the supporters of the chro-
mosome theory whose enthusiasm seems to be too strong for
their judgment. He is careful to point out that he found
no lai'va in which the part of the skeleton presenting mater-

346 Tlw Unity of the Organisw,

nal characters, were these characters exclusively maternal,
in spite of the fact that in some of the embr^^os in the two-
cell stag^c tlie nucleus of one of the cells seemed to be purely
female. That the variations from pure femaleness toward
the hybrid condition of this part of the skeleton were due
to fragments of chromatin from the male nucleus having
passed into the female nucleus, he regards as probable, for
he could observe that in the reconstruction of the nuclei,
both male and female, from the chromosomes during fertili-
zation, the male chromatic granules did not always remain
together, but were scattered about more or less, sometimes
mingling quite intimately with those from the female nucleus.
This would seem to give opportunity for contamination, as
one might say, of the female nucleus w^ith male chromatin
even in those cases where, after the nuclei were reconstructed,
nothing of such contamination could be observed. But
Herbst is quite conscious of the danger in this sort of ex-
planation, that namely, which having found some observa-
tional ground on which to base an explanatory assumption,
proceeds to push that assumption to whatever lengths may
be necessary in order to explain the facts as it is desired
they should be explained.

The weight of this piece of evidence in favor of chromatin
as one "hereditary substance" is undoubtedly great, and is
enhanced not a little by the conservatism of the investigator
wlio presents it. How far it goes toward proving that chro-
matin is the hereditary substance is quite another matter,
and one to be dealt with later.

The Connection of Sex with a Particular Chromosome

The proof recently brought out that in some organisms
sex is connected with a particular chromosome in the germ-
cells is another point scored for the chromatin theory of
heredity. The first phase in this discovery consisted in

Chrowatin as ''Hereditary Sfihsfance'' 347

making out tliat there are two sorts of spermatozoa from
one and tlie same male in certain insects, the difference be-
tween the two being that the head of one kind contains an
element or body not present in tlie other. At first there was
difference of view as to the anatomical nature of this extra
element. Some regarded it as akin to the nucleolus rather
than to the chromosomes. The idea of dimorphic sperma-
tozoa was first clearly expressed by H. Henking as follows,
"I believe every unbiased observer will view with me this
spherical element [of the sperm head] sliarply distinguish-
able from the otlier chromatin, as the nuclear body [present
in part of the speraiatids]. Thus is revealed the important
fact thht we have two kinds of spermato::oa : one kind pos-
sesses a nucleolus, the other does not.'''' ^■'

C. E. McClung, another student of spermatogenesis, first
suspected that these two kinds of spermatozoa have some-
thing to do with the two sexes. The important paper in
which this hypothesis is set forth was published in 1902,
and within the brief period since that date, the hypothesis
has been supported and extended by such a mass of obser-
vation that its universality for at least the animal kingdom
seems not improbable.

The exact terms in which McClung stated the hypotheses
merit attention. He says, "Briefly stated, then, my con-
ception of the function exercised by the accessory chromo-
some is that it is the bearer of those qualities which pertain
to the male organism, primary among which is the facult}^
of producing sex-cells that have the fqrm of spermatozoa." ^''
Noteworthy for our discussion is the difference of view
concerning the chemico-morphological nature of the extra
element in the spermatozoan as shown by these two quota-
tions. It was regarded as sharply distinguished from the
chromosomes by Henking, but as a true chromosome by Mc-
Clung. The great preponderance of later opinion has sided
with McClung, but very recently the question has been

348 The Uniffj of the Organism

raised again, though in a quite different form.

This demonstration of the existence of two kinds of sper-
matozoa and McClung's guess as to its meaning came at
an opportune time for their influence upon investigation.
On several accounts interest in cell structure was already
largely centered in the chromosomes. Furthermore, the
Mendelian mode of inheritance was rediscovered almost
simultaneously with the publication of McClung's hypothesis.
Now the most fundamental thing so far recognized in con-
nection with this sort of heredity seems to be separateness
and stability of the attributes of organisms ; the unit char-
acter concept, it has been usually called. As soon as the
natural suggestion was made that sex itself might be a unit
character, the alluring surmise was close at hand that attri-
butes of adult organisms which segregate in inheritance, that
is, which come out in pristine purity in the children, no
matter how much they may have been obscured in the par-
ents, miglit be connected with particular chromosomes. Add
to these circumstances the more general one that the estab-
lished facts and proposed hypotheses were congenial to the
elementalist spirit already powerful in biology, and the
tremendous impetus to work on the fascinating problems of
the mechanics and cause of heredity in so far as sexually
propagating organisms are concerned, can be easily under-
stood.

It is doubtful whether in the whole history of biology
any other fifteen-year period has seen greater intensity of
investigation or a larger number of notable observations
and discussions on any topic than has the period since 1900
on the problem of heredity and sex. And "determinants",
(hypothetical somethings in the germ which "carry" and so
explain characters of the adult), modified into "determin-
ers" apparently for the purpose of disguising the unpala-
tableness of Weismannian metapliysics, have played a very
great part in the efforts that have been made. Indeed, there

Chromatin as '^Hereditary Substance^' 349

seems to have been somctliinf^ talismanic in the word, It hav-
ing inspired workers with the behef that since deteinniners
belong to the realm of causality, quest after them absolves
the seeker from the humble task of telling in ordinary de-
scriptive fashion what they themselves are. Although no
serious effort has been made in this period to give an ac-
count, either morphological or physiological, of determiners,
excepting that they determine, the fact that evidence has
been forthcoming In abundance that chromosomes act as
though they were depositories, or carriers of determiners if
such exist, has increasingly vivified and strengthened faith
in them, and so has made the determiner hypothesis a stimu-
lant to research in even greater measure than did its im-
mediate predecessor, the determinant hypothesis of Weis-
mann.

If the value of a "working hypothesis" is to be judged
solely by the amount of work incited by it (though for rea-
sons which it is beyond the scope of this volume to present
I deny the adequacy of such valuation), this hypothesis has
surely justified itself. If one mentions only the foremost
workers in this field the list is by no means short and con-
tains biologists of the first rank. The names of Boveri,
Correns, Doncaster, Goldschmldt, Guyer, R. Hertwig, King,
McClung, Meves, Montgomery, Morgan, Stevens, and E. B.
Wilson, would be sure to appear in any list of students dis-
tinguished for what they have contributed to the advance-
ment of biology during the last two decades, and the prob-
lem of the cytological basis of heredity has received a gen-
erous share of the attention of all these.

The fruitage of effort since McClung published his hypo-
thesis must now be summed up, though naturally only the
baldest essentials can be included. McClung conceived the
accessory chromosome to be the bearer of those qualities
which pertain to the male. In other words, he conceived
that jnaleness in the insects to which his studies related was

350 The Unity of the Organism

caused by the extra chromosome of the sperm cell. Two
distinct questions suggest themselves to the critically
minded: assuming it proved that spermatozoa having extra
chromosomes do induce eggs to develop into males in some
animals, how generally is this true for sexually propagating
organisms? And assuming it true either universally or only
in a few animals, what is the real meaning of the statement
that the accessory element of the sperm is the "bearer of
those qualities which pertain to the male organism"?

The answer to the first question alone concerns us now,
though the answer to the second is far more fundamental
and upon it depends in large measure the significance of
whatever answer may be forthcoming to the first.

The arguments by which McClung supported his hypothe-
sis were rather general and indirect, and it is possible to
state in a single sentence the main outcome of later research
relative to it. A connection between sex and particular
chromosomes has been definitely proved for a large number
of animals ; but the particular connection supposed by Mc-
Clung, namely, that the accessory chromosome of the sperm
produces a male, has not been proved. In 1911 Wilson, epit-
omizing the results of his own researches and those of others
using terms necessitated by discoveries since 1902, said,
"The observed relations of the X- and Y-chromosomes to
sex are not theories, but facts." ^^ The evidence seems un-
doubtedly to justify this statement; so information as to
what the X- and Y-chromosomes are will furnish informa-
tion of the dependence of sex upon chromosomes.

Discoveries were made soon after the enunciation of Mc-
Clung's hypothesis that seemed almost certainly to connect
the extra chromosome of the sperm not with the production
of a male, but of a female. "The decisive evidence," writes
Wilson, "in regard to this question was first produced by
independent investigations upon Hcnii})tcra and Coleoptcra
by Miss Stevens and myself in 1905-1906.'* ^^ This evidence

Chromatin as '^Hereditary Substance** 351

was obtained by a c()nn)aratlve study of tlie chromosomal
number and cliaractcr in the body .cells as well as in the
germ-cells of botli males and femalcl^s. Miss Stevens's state-
ment of results may be given. Referring to tlie previous
investigations by herself and Wilson on a considerable list
of species of insects belonging to the orders above men-
tioned, she said that in all cases where an odd chromosome
occurs in the male germ-cells, a pair of such chromosomes
occurs in the body cells of the female ; from which the con-
clusion follows that an Qgg fertilized by a spermatozoan
containing an odd chromosome must produce a female in-
sect.

But a variation from this scheme was found which, though
not contradictory to the principle involved, made it neces-
sary to give this cliromosome some other designation. The
designation chosen by Wilson was X-chromosome, or as
later observations seemed to justify, sex chromosome. "X-
chromosome" is then, essentially synonymous with "acces-
sory chromosome," and "Y-chromosome" refers to a
chromosome in some species as a mate to the X-chromosome.
But since the Y-chromosome constitutes a further compli-
cation, though not a fundamental modification of the prin-
ciple of the relation of chromosomes to sex, the purpose of
this discussion would not be furthered by going into the
subject in more detail, interesting as it is from various otlier
standpoints.

The other kind of evidence which we will mention con-
necting sex with chromosomes has come from animals which,
like some bees and wasps, propagate by fertilized eggs part
of the time and by unfertilized or virgin or parthenogenetic
eggs the rest of the time. As soon as the fact had been
discovered that a chromosomal difference between the two
sexes occurs in some animals which always reproduce bi-
sexually, the likelihood of a difference between the chromo-
somes of parthenogenetically produced females, ordinary

352 The Cnitij of the Organism

females, and males of the same species, readily occurred to
biologists, and a study of the subject has been made by sev-
eral investigators. The state of things found in the honey
bee, perhaps the most familiar example of virgin propaga-
tion, illustrates the principle involved. It has long been
known that female bees (queens and workers) are produced
from fertilized eggs, while males (drones) are produced from
non-fertilized eggs. If the dependence of sex on chromo-
somal peculiarities knoWn to occur in some insects be true
generally, then the eggs of bees which develop partheno-
genetically might be expected to differ as to their chromo-
somes from those which develop after fertilization. This
expectation has been definitely realized. Before maturation
the male germ-cells have sixteen chromosomes and the fe-
male cell thirty-two. Reduction by one-half in the number
of chromosomes which occurs in typical spermatogenesis
does not take place here, so the speraiatozoan receives the
full sixteen chromosomes. From this it results that the fer-
tilized ^gg, containing thirty-two chromosomes (sixteen hav-
ing been added by the spermatozoan), has undergone the
usual reduction of chromosome-number during maturation,
leaving it sixteen. "The fission spindle of the unfertilized
Qgg contains only the haploid number of chromosomes (16),
the fertilized o^gg contains naturally the diploid number
(32)." 1^

"Here, then," says Doncaster, "is a clear case of sex
determined by, or at least in connection with, the presence
of a definite number of chromosomes ; when the full, or
double, number is present, the individual is a female ; when
only the half number is present, it becomes a male." ^^ With
important variations for the different animal groups, the
first part of this statement has been found to be true for
quite a list of animals which reproduce parthenogenetically
a portion of the time, among these being certain wasps.

Chromatin as '^Hereditary Substance'' .353

gall flies and phjUoxerans.* And observations have lately
been published which strongly indicate the dependence of
sex upon chromosomes in other animals in which partheno-
genesis and hermaphroditism occur. This is notably true
of aphids, certain nematode worms, and a pteropod mol-
lusc. Summing up, we may say, then, tliat in a considerable
number of animals sex is proved to be hereditary and to be
connected with the chromosomal condition of the germ-
cells.

The Con/nection of Mutation with Particular Chromosomes

Finally, the most surprising evidence in favor of the
theory that chromosomes are bearers of heredity, is the dis-
covery that certain attributes in some animals and plants,
not necessarily peculiar to either one sex or the other, but
which arise as mutations and are transmitted in Mendelian
fashion, are connected with particular chromosomes. The
best investigated examples are furnished by the evening
primroses, plants which have become famous in connection
with the mutation theory.

Mr. R. Ruggles Gates, one of the foremost workers in this
specialty, has lately epitomized the facts and views held rela-
tive to the chromosomal characters of plants. He writes

* The investigators who have contrihuted most to the descriptions of
the chromosomal conditions of the honey bee are J. F. Meves {Die
SpermatocytenfeUunf/en bei der Honlghiene, Arch. f. Mikr. Anat. Bd. 70,
p. 414, 1907) and H. Nachtsheim, referred to above. Meves and J.
Deusberg {Die Spermaiort/fenfeiiimf/en bei der Ilornisse. Arch, fiir
Mikr. Anat. Bd. 71, 1908) have investigated the wasp. The gall flies
have been studied by L. Doncaster. {Gameto gene sis of the Gall fly
Neuropterus LEXTicrLARis Proc. Roy. Soc. B. 82, 1910, p. 88 and B. 83,
1911, p. 476.) The germ-cells of certain Phylloxerans have
been the subject during the last ten years of some of T. H. Morgan's
most important studies. His first paper, {The Male and Female Eggs
of Phylloxerans of the Hickones, Biol. Bull. Vol. 10, p. 210) was
published in 190fi. In all he has written something like a dozen
papers on the subject, the last so far as I know having appeared in 1915
{The Predetermination of Sex in Phylloxerans and Aphids. Jour. Exper.
Zool. Vol. 19, Oct. 1915, p. 285).

354 The Unity of the Organism

". . . in the genus Oenothera the original number of chro-
mosomes is 14. This is true of Oe. Lamarckiana and many
other species. Duplication of one of these chromosomes
through an irregular mitotic division has led to 15 in Oe.
lata, a characteristic mutation which has occurred both in
Oe. Lamarckiana and in certain races of Oe. biennis. The
same chromosome number occurs in semilata and in a very
different form from Sweden which I have called incurvata.
De Vries has recently described still another form having 15
chromosomes. It w^as derived from Oe. biennis semi-gigas
pollinated in part from Oe. biennis . . . Hence we may say
that whenever a germ-cell having 8 chromosomes fertilizes
a normal germ-cell a new form is produced. . . . Oe. mut.
gigas is a prototype of another series of still more closely
parallel mutations in which the chromosome series is doubled
— 28 — the plant being a cell giant and not merely gigantic
in its external dimensions. ... A third series of morpholog-
ical mutants is the semigigas series, having 21 chromo-
somes. ... Another important feature of mutations which
has not hitherto been emphasized is the fact that each is the
result of a cell change which is represented in every part of
the organism. The cells of Oe. lata constantly have 15
chromosomes, in whatever part of the plant they have been
examined. Similarly in Oe. gigas even the most specialized
tissues retain the double number of chromosomes transmitted
to them." 21

The examples of connection between mutations and chro-
mosomes which are now attracting most attention are fur-
nished by the fruit flies (DrosophUa). Biology is especially
indebted to Professor Morgan's genius for experimentation
for the investigations in this field. The explanation of the
behavior in heredity of mutant attributes in DrosophUa
elaborated by Morgan and his co-workers is admittedly
hypothetical and is consequently not really entitled to a
place in this section, the aim of which is to present cases of

Chromatin as ''Hereditary Substance'' 355

actually proved connection between hereditary attributes
and clironiosomes. Morgan's hypothesis is, however, so in-
teresting and seems so likely to be proved partly true (that
is, true to the extent of there l)eing some sort of connection
between the attributes in (Question and chromosomes), that
it seems desirable to present the most salient parts of the
theory.

That the case is, as above indicated, still in the hypotheti-
cal stage, seems not to be appreciated by some enthusiasts,
though fortunately Morgan is not one o£ these. In the
preface to the volume The Mechanism of Mendelian Heredity
jNIorgan writes : "But it should not pass unnoticed that
even if the chromosome theory is denied, there is no result
dealt with in the following pages that may not be treated
independently of the chromosomes ; for we have made no
assumption concerning heredity that cannot also be made
abstractly without the chromosomes as bearers of the postu-
lated hereditary factors." ^^

The observations on which Morgan's hypothesis rests be-
long to two very different categories, and these categories
pertain to parts of the organism anatomically far away
from each other, namely, to the union and separation or
"segregation" of the hereditary attributes of adult organ-
isms that propagate bisexually, and to the union and sep-
aration of chromosomes of the germ-cells during maturation
and fertilization in these same organisms. As an illustration
of the first part of this statement take one of Mendel's own
cases, that of the table pea having roundish seeds crossed
with a variety having angular and deeply wrinkled seeds.
All the seeds of plants arising immediately from this cross
(the Fj generation) are round. But if now the plants of
this Fi lot are pollinated among themselves, their immediate
progeny (the F2 generation) will have both round and
angular seeds in the proportion of three round to one angu-
lar. In a word, since the F2 plants produce seeds corre-

S56 The Unity of the Organism

sponding in form to the seeds of both their grandparents, it
is certain that the germs of their parents must have con-
tained some sort of a combination between round-producing
and angular-producing capacities of the genns, even
thougli those parents revealed nothing of that capacity so
far as their own seeds were concerned. And it is certain,
too, that whatever the nature of the combination in the
germs of the P\ generation, it is such as to permit a separa-
tion of the capacities for the seeds of the Fo generation.

In 1865, when Mendel announced these observations, noth-
ing was known about pea germs, or for that matter about
any other germs, that could remotely suggest what their
constitution is in virtue of which they possess peculiar ca-
pacities. Nor was it until cytological research had accu-
mulated a good deal of knowledge of the chromosomes that
positive light from the side of germ morphology and
physiology was thrown on the subject.

Chromosoines and the Mendelian Mode of Inheritance

The pregnant hypothesis that the combination and the
separation of hereditary attributes in the fashion discovered
by Mendel is not only paralleled but explained by combina-
tions and separations of chromosomes in the germ-cells, was,
according to Morgan, Sturtevant, Bridges, and Miiller, first
stated "in tlie form in which we recognize it to-day," by W.
S. Sutton. E. B. Wilson has informed us how the idea came
to expression almost simultaneously by Mr. Sutton, then a
student of zoology in Columbia University, and W. A. Can-
non, a botanical student in the same University.

The basis and formulation of the hypothesis are pre-
sented by Mr. Sutton in two papers published in the same
volume of the Biological Bidletin. In order to appreciate
the full cogency of the argimaent in favor of the hypothesis,
it is necessary to go a little farther than we have hitherto

Chromatin as ""Hereditary Substance^'' ^^iTl

into tlie structure and maneuvering of the chromosomes of
the germ-cells during the "ripening" of the germ-cells. The
facts usually taken as the starting point for the hypothesis
are that all the cells, both body and germ, of an ordinary
sexual plant or animal have a constant number of chromo-
somes, the number being characteristic for the species ; that
before fertilization, an essential feature of which is the
union of male and female chromosomes, the chromosome
number of both male and female cells is reduced by one half,
excepting in those cases wliere there is an odd or accessory
chromosome, so that the union of the chromosomes in ferti-
lization restores the number typical of the species ; that the
final adjustment gives the fertilized ^gg and all the cells
arising from it supposedly equal portion of chromatin from
each parent ; and finally, that the chromosomes of the germ-
cells in many animals, if not in all, are not all alike either
in form or size.

Proceeding from these facts Sutton studied the germ-cells
of the lubber grasshopper with reference to the question of
wliether the differences in size and form of the chromosomes
are haphazard and meaningless or have some constancy,
especially in relation to their maternal and paternal sources,
and in the way they couple with one another in fertilization.
Summarizing the results for the germ-cells as they grow
and multiply before the ripening process sets in, he con-
cluded that during this period the chromosome group of
each germ-cell is composed of two equivalent chromosome
series, each series consisting of eleven chromosomes differing
among themselves in size, and that in all probability one of
these series comes from the father and the other from the
mother. Furthermore, he believed that the reduction in
number which takes place in this ripening stage and is known
as synapsis, is accomplished by the union of two series in
such fashion that each member of the maternal series unites
with one of corresponding size, its mate of the paternal

358 The Unity of the Organism

series, and that in the very last division before the trans-
formation of the unripe cells into eggs and spermatozoa, a
separation of the chromosomes which united at synapsis oc-
curs, so that each Qgg and each spermatozoan gets the full
series of eleven, characteristic of the species, some, however,
being of maternal and some of paternal origin.

In his first papei% Sutton merely mentioned Mendelian in-
lieritance in connection with the chromosome scheme he had
considered. "I may finally call attention/' he said^ "to the
probability that the association of paternal and maternal chro-
mosomes in pairs and their subsequent separation during the
reducing division . . . may constitute the physical basis of the
Mendelian law of heredity." "^ His second paper is devoted
to an elaboration of this suggestion. Mendel pointed out that
where attributes of Iwbrids behave in heredity in the peculiar
wav discovered bv him. if one of the constant characters, for
example^ the dominating one^ be designated by A and the other^
the recessive^ by a, and the hybrid form in which the two are
combined by Aa, then these two differentiating characteristics
of the development series in the progeny of the hybrids will
give the formula: A -j~ 2.4a -|- a. This comes about on the sup-
position that the uniting of these characteristics follows the law
of chance; that is, that a male hybrid with attributes Aa pairing
with a female hybrid having the same attributes, gives :

A a ^ A a

or A 4- 2Aa -|- a, since AA and aa can be nothing more than
A and a as here used.

What in essence Sutton did was to sliow that sucli a chromo-
some scheme as he had partly proved and partly conceived
to exist in tlie germ-cells of the lubber grassliopper, could be
bronglit under the identical expression tliat we have just seen
Mendel deduced for the attributes of peas. If, Sutton reasoned,

Chromatin as "Hereditary Substance*' 359

each chromosome of any series, has a corresponding one in any
other series, and if these have such an identity and freedom
to combine and separate as the discussion had assumed, then
if a given chromosome of the father be designated \)y A and its
mate in the mother by a, in synapsis there would arise Aa, which
on reduction division preparatory to ripening of the eggs and
sperm would produce two kinds of eggs and two kinds of sperm
relative to this set of chromosomes, namely male A and female
A ; and male a and female a. These if equal in number and
equally free in their movements would give in fertilization :

Male A + Female A = AA

" A -j- " a = Aa

" « + " A = aA

a -\- a — aa

Or since Aa and a A are alike the expression becomes A A -f"
2Aa -j- aa as the distribution, or again A -\- Aa -\- a as the
sum of possibilities of each chromosome pair. "Thus," Sutton
says, "the i^henomena of germ-cell division and of heredity are
seen to have the same essential features, viz., purity of units
(chromosomes, characters) and the independent transmission of
the same." ~*

We must now return to the truly remarkable discoveries
made by Morgan and his students and collaborators on mu-
tations in Drosophila and on the behavior of the mutant
attributes in heredity. These have consisted in showing that
such a relation between attributes and chromosomes as that
assumed in this relatively simple scheme worked out by
Sutton may be carried out in much detail both as to attri-
butes and chromosomes. An especially ingenious and fas-
cinating aspect of the theory as it has been elaborated large-
ly under Morgan's leadership, is that which shows the
possibility that different parts of one and the same chromo-
some may correspond to several distinct attributes of the
adult; that these attributes may or may not be inseparable
from one another, and that when they are separable they
may be transferred from one sex to the other, presumably
by the transferrence of factors in one part of a chromosome

360 The Unity of tJie Organism

of a given pair to the other chromosome of that pair.

So rapidly have come the striking observations in this
field, and so striking have been the theoretical interpretations
set forth that many biologists who have been admiring on-
lookers, have seeming!}^ failed to discriminate just how much
of what has been presented is fact, how much legitimate in-
ference, and how much hypothesis in the strict sense. It is,
consequently, eminently fortunate that Morgan himself has,
as noted above, given us an explicit even though an inade-
quate statement of how the case stands in this regard. The
sentence quoted some pages back, "We have made no as-
sumptions concerning heredity that cannot also be made
without the chromosomes as bearers of the postulated hered-
itary factors," -^ should be recalled. The case standing
thus, the present discussion would not be furthered by going
into more of its details.

And so we come to the end of our examination of the
observational evidence favorable to the theory that heredi-
tary attributes in bisexually propagating organisms are in
some way and to some extent dependent upon the chromo-
somes of the germ-cells. The conclusion must be, it seems,
that not many of the major theories in biology are more se-
curely established than this. Thus stated, the chromosome
doctrine not only takes its place along-side the cell-doctrine,
but it supplements, and in fact, partly supplants the cell
doctrine. Never again, for example, can the cell be con-
ceived, as many earlier cellular elementalists were wont to
conceive it, as The Ultimate Unit of organic beings.

In several instances presented by the foregoing review of
the chromosome theory of heredity, notably in that of the
pollen grains of flowering plants where the final act in fer-
tilization appears to be accomplished by the chromatin alone
(see p. 343), the chromatin manifestly constitutes a unit
beyond the cell and hence nearer to ultimateness than is the
cell.

Chromatin as ^''Hereditary Substance^''

361

REFERENCE INDEX

1. Kofoid 939 14.

2. Wilson, E. B. ('00).... 165 15.

3. Wilson, E. B. ('00) 308 16.

5. Hertwig, O. ('12) 50 17.

6. Hertwig, O. ('12) 51 18.

7. Heidenhain 241 19.

8. Jordan ('16-1 ) 210 20.

9. Hooker 401 21.

10. Szily 145 22.

11. Strasburger ('09) 104 23.

12. Boveri 3(60 24.

13. Morgan, T. H. ('15) 62

Herbst 266

McClung 47

McClung 72

Wilson, E. B. ('11) 257

Wilson, E. B. ('11) 258

Nachtsheira 228

Doncaster . . .

Gates

Morgan, T. H.
Sutton ('02) .
Sutton ('02) .

et al.

57
522
viii

39
237

I

Chapter XIII

EVIDENCE FROM PROTOZOANS THAT SUB-
STANCES OTHER THAN CHROMATIN ARE
PHYSICAL BASES OF HEREDITY

TAKING it as proved that in most sexually propagating
organisms heredity is dependent on chromosomes, thus
making the view that chromosomes are bearers of heredity
legitimate in a certain sense, a fundamental question must
be examined before the discussion can be regarded as hav-
ing even an approach to comprehensiveness. This question
may be stated thus : is heredity dependent on the chromo-
somes alone, that is, to the exclusion of other parts of the
cell; in other words, are chromosomes the sole "bearers of
heredity"?

At the outset of this inquiry we must recall what heredity
is as understood in this treatise. It is resemblance between
living beings due to descent. This is the definition which in
an earlier section we decided is more satisfactory than any
other when due consideration is given not only to the phe-
nomena of organic propagation themselves, but also to the
historic usage of the word. Another thing about heredity
insisted upon on earlier pages should be recalled: all stages in
the development of an individual are as truly manifestations
of heredity as is the final or adult stage. And finally, the
reader is asked not to forget the deprecation expressed
early in the discussion of the unwarrantable practice with
many recent writers on heredity of eitlier ignoring asexual
propagation altogetlier or tossing it aside as presenting no
problem or anything of significance to the geneticist.

302

Evidence from Prntozoavs 363

If WG liold firmly to this broad but, in the light of facts,
only adequate conception of heredity, the general answer to
the questions stated above as to the relation of chromosomes
to heredity will come without equivocation. We may give
the answers now categorically, then look at the facts which
compel them. Neither chromosomes nor chromatin are the
sole bearers of heredity. Factors for hereditary attributes,
if the teiTn has any real meaning as thus used, are "carried"
by the cytoplasm no less than by the chromatin. Many,
probably all living parts of the cell, and not the chromatin
and chromosomes alone, are the physical bases of heredity.

Evidence From the Ontogeny of Variotis Protozoans

Beginning the discussion again with the lower organisms
and advancing to the higher, we first examine the develop-
ment of a few protozoans ; and the reader is urged to take
what follows in connection with the chapters on the struc-
ture, and especially on the development of protozoans.

(a) Stentor

The development of the "trumpet animalcule," Stentor,
having been instanced as a genuine, often complex ontogeny
in protozoans, our study of heredity in the protozoa may
well begin with this animal. The figures 11, 12, 13, and 14
accompanying the earlier presentation will serve us now.
Reference to the account given in the former discussion finds
that one of the main points brought out was that in repro-
duction a whole series of the Stentor's external organs arise
de novo, that is, independently of the corresponding organs
of the parent ; and that these take their origin in the surface
layer or ectoplasm, and outer part of the endoplasm. "And
this de novo mode of origin," we read, "is followed by a
whole series of organs and tissues ; the cilia and membranel-
lae of the aboral zone; the mouth, velum and pharynx; the
frontal field; the ramifying zone; and the contractile vacu-

364 The Unity of the Organism

ole and excretory pore." The question which chiefly con-
cerns us now, but which received no consideration in the
earlier treatment is, what part, if any, does the chromatin
of the nucleus play in the initiation and development of these
organs? One of two courses must be followed if the
cliromatin theory is to be proved in a specific instance like
this : either the developmental facts presented must be
sliown not to be subject to heredity or it must be proved
tliat they are caused by the chromatin.

That many modern students of heredity have strongly
tended by implication if not expressly to pursue the first
mentioned course, cannot be successfully disputed. This
was dwelt upon in the early part of our discussion of hered-
ity and we may hope its utter unwarrantableness was re-
vealed. As a consequence our only task now is to inquire
what the evidence is that the developments before us are
causally explained by the nuclear chromatin — or for that
matter by chromatin of any other kind.

The method of handling the evidence, not only in this
particular case, but in all others with which we shall deal,
must be stated at the outset. Briefly, our task is not to
prove what chromatin does not do, but to point out what
cytoplasm and other substances do in connection with the
development of the organs under consideration. Otherwise
stated, just as in the effort to decide whether or not chro-
mosomes and chromatin are the physical basis of heredity,
we sought for evidence of the direct participation of these
in the production of organs and parts, so now we have to
inquire as to whether or not extra-nuclear and non-chro-
matic parts of the cell participate in the production of
organs and parts.

"The first sign of fission," Johnson has already been
quoted as saying, "is tlie formation of a rift (the anlage
of the new aboral zone) in the pellicula and ectoplasm, near
to and almost parallel with the left boundary stripe of the

Evidence from Protozoans 365

ramifying zone." The list of structures enumerated as aris-
ing de novo should be recalled and the furtlier fact recog-
nized that like this first sign of fission, they all pertain to
the sujx'rficial ])art of the auinial's body. "The gradual
evolution," we ])reviously (juoted fJohnson as saying, "of
structures so coin[)licated as luenibranellae, from a mass
of indifferent protoplasm, is very striking."

What of the nucleus while these parts are being started in
the indifferent proto))lasm? Considering the time at which
Johnson did this piece of work, his account of the behavior
of the macronucleus during fission is very full. "At the be-
ginning of fission," he says, "the mcganucleus has its usual
spiral disposition in the body. The first alteration, just
previous to the appearance of the new pharynx, is a straight-
ening of the nucleus and disappearance of the commissures,
the nodes becoming appressed." ^ The various positions
and conditions of the nucleus here referred to are shown,
mgn, of the figures.

The complete obliteration of the nodulation typical of the
resting nucleus, the great elongation of the nucleus and its
gradual reformation at each end, and the final division after
the preparation for body-fission is far advanced, are indi-
cated in the figures. Johnson speaks of the great activity
of the nucleus in some of its stages showing something ap-
proaching an amoeboid character ; but there is no intimation
either by position or by activities that the nuclear changes
are correlated in any detail with the formation and growth
of new organs of the body.

But, it will be said, prevalent views about the macronu-
cleus would not lead one to expect it to participate in the
development of organs. The micronuclei of the group of
organisms to which Stentor belongs, being chiefly concerned
in reproduction, would be presumed to contain the hereditary
substance, and so to them and not to the macronucleus ought
inquiry to be directed for evidence, if such there be, of

366 The Unity of the Organism

nuclear participation in the development of organs. John-
son's observations on these nuclei were very incomplete, but
such as he made are significant. H'^ found undoubted evi-
dence that some of them divide when the animal divides ;
but in no case was he able to follow all the details. The
points made out which seem to bear on the main question
before us are : "I made out," he says, "65 micronuclei adher-
ent to the two [pieces of the macronucleus], but none were
found in the spindle stage except the two above-men-
tioned." ^ The point of interest for us is that so far as the
evidence goes, the dividing micronuclei were closely related
spacially to the macronucleus, which is another way of
saying that they were not closely related spacially to the
developing organs, so that if they played any direct part
in this development they did so through some "action at a
distance" — a sort of action which, though as we now know
may be a real factor in organic development, can be in-
voked as an explanation of morphogenesis only with the
greatest caution.

Another point of interest touched by Johnson's observa-
tions concerns the time of the division of the micronuclei
relative to the division of the macronucleus. When the
dividing micronuclei were observed the macronucleus was
"at complete condensation and in two distinct pieces." -
Turnina: to the account of the behavior of the macronucleus
during division of the animal, we read, "the meganucleus
has assumed the spherical shape [state of condensation]
when the pharyngeal funnel has begun to form" ; ^ in other
words, at a time somewhat earlier than that shown in figure
12. That is to say, so far as the observations go, the in-
dications are that fission of the animal begins in the cyto-
plasmic part of the body not only before the macronucleus
undergoes any change, but also before the division of the
micronuclei.

Apparently the behavior of the micronuclei dunng asex-

Evidence from Protozoans 367

ual fission and development in Stentor has not been reexam-
ined since the pubHcation of Johnson's paper, so all the
Ijf^-ht we have on the part played by the micronuclei in the
ontogeny of these animals is still fragmentary and indirect
so far as the particular point now before us is concerned.
Muslow ^ presents certain observations on these bodies dur-
ing conjugation that bear on tlie point indirectly. For one
thing, he confirms Johnson's observation tliat the micro-
nuclei are situated typically close around, indeed are adher-
ent to the macronucleus. But perhaps the most significant
point for us brought out by Muslow's studies is the indica-
tion which he finds that the wandering micronuclei, that is,
those that pass from one animal into the other during con-
jugation, are carried passively, in part at least, by the
cytoplasm of the animal.

In a later section we shall consider the question of how
the recent studies on the migration of chromatin granules
from the nucleus into the cytoplasm, and also on the chro-
midia and on the mitochondria, affect the problem of nuclear
participation in organ development. But our general posi-
tion relative to this whole matter may be stated here as
touching specifically the organogenesis of Stentor. In this
section we are trying primarily to find what role the extra-
nuclear parts of the cell play in development, so what the
nucleus does or does not do concerns us only secondarily.
This being the case, when Johnson says (and it should
be remarked that descriptions of like purport by other stu-
dents concerning other protozoans, are almost numberless),
the "gradual evolution of structures so complicated as mem-
branellae from a mass of indifferent protoplasm," we take
the description at its face value and hold that no matter
what outside influences may operate on this protoplasm,
it itself plays an active and essential part in bringing about
the results. And from this we further hold it to follow that
since these results are a number of organic parts which

368 The Unity of the Organism

because of their resemblance to the corresponding parts in
the parent organism are manifestations of heredity, the
^indifferent protoplasm"^ which gave rise to the parts is
more certainly a ^''physical basis of heredity''" than woidd
be any extraneous part or substance that might be shown to
**influence" the substance which itself transforms into the
parts.

The essence of my contention ma^^ be briefly stated thus :
recognizing as every biologist must, that transformation is
an absolutely indispensable element of organic development,
when the transformation of an "indifferent mass of proto-
plasm" into definite organs or parts takes place before our
eyes, we are bound by principles of objective science to be-
lieve that the transforming substance itself is actively and
not entirely passively concerned in the operation. We are
thus bound since, by supposing that if we cannot "causally
explain" the observed process we must assume that the real
cause, the ultimate explanation, lies deeper and in some
other substance, we are committing ourselves to a course
which, if consistentlv followed, denies the validitv of all ob-
servational knowledge. Such repudiation would result from
the fact that as soon as we succeed in bringing the "other
substance" under observation we are always confronted with
the same difficulties as to causal explanation which we met
in the first instance. In observing a cause, or the "seat"
of a cause, in actual operation, we are never able to satisfy
ourselves as to exactly how or why it operates as it does.
Supposing, for example, we were able to see the atoms or
even the electrons of nitrogen, carbon, oxygen and so on, at
their work in producing membranellae in Stentor, does any
one suppose we should be able to see fully why and how they
do it? Who in modern times refuses to believe that the force
of gravitation is partly inherent in the earth itself and in
every other body, though no amount of examination of the
bodies can make out fully how and why the bodies have

Evidence from Protozoans 369

such a force?

He wlio persistently denies that a sensible object is ex-
planatory in a causal sense of the forces and activities it
manifests because he cannot see the whole rationale of the
manifestations, but insists that the final explanation must
lie deeper, is at heart an apostate to obsei'vational science,
and it matters not at all so far as principle is concerned,
whether the invisible "deeper" cause, supposed to be final,
be conceived as pure Matter, pure Energy, pure Spirit,
or a Divinity.

To recapitulate: the only conclusive proof of what bodies,
whether chromosomes, mitochondria or any other substances,
are "bearers of heredity," is either direct or indirect ob-
servation that these bodies or substances transform into
organic parts which after transformation are seen to re-
semble the corresponding parts of the organism's parents.
And only such hypotheses concerning the nature of germ-
cells as are made in strict accordance with the rule of evi-
dence thus fomiulated, are legitimate hypotheses.

So far as fundamental principles are concerned, we might
consequently go no further with the examination of details.
However, since the principles are in reality only the general-
ized details, and the details are the mother liquor, so to say,
of the science of heredity, we can hardly avoid pushing our
examination somewhat farther. We will look at a few more
examples among the protozoa where cytoplasm and various
substances other than chromatin are a physical basis of
heredity, these examples being chosen to connect with our
studies of the anatomy and development of protozoans in a
former chapter. It will be recalled that from the great
and highly developed class of Ciliata to which Stentor be-
longs we examined Diplodinium and Stylonychia, shown in
figures 1 and 3.

370 The Unity of the Organism

(b) What Study of the Ontogeny of Diplodinium Will

Probably Discover

Unfortunately^, next to nothing is as yet known about the
ontogeny of Diplodinium. ^Nlr. Sharp, who has taught us so
much about its adult anatomy, has its development under investi-
gation, but until his studies are brought to a conclusion we can
do no more than ask questions pertinent to the discussion in hand.
Let us fix attention upon the skeleton and the neuromotor ap-
paratus, for example, figure 1 (sk. lam., m. m. and circ. oes.
ring) . When the origin and growth of these organs come to
be studied, judging from our general knowledge of development,
what will be observed will be a transformation in one way or
another of a portion of the cytoplasm into these parts. Nor is
it at all unlikely that, assuming that the work is done with the
best technical methods available, chromatic material from the
micronuclei will prove to play a part in tlie differentiation. Does
any one suppose that the investigator will be able to prove that
the seeming participation of the cytoplasm is a delusion and
that the only form-determining agent is the chromatin? Yet
nothing less, we must insist, will be required to prove the hypo-
thesis that chromatin is the hereditary substance in these animals.

(c) The Origin of Flagella

When presenting evidence of the direct participation of the
nuclear chromatin in the production of organs, we pointed to
the growtli of the axial filament of the flagellum in certain pro-
tozoans as an especially clear case. Now we must inquire about
the origin of the other part of the flagellum — for the fact of
its liaving an axial part or core necessarily implies that there is
another part. Seemingly it is fully established that the axial
core is enclosed in a contractile sheath or envelope as described
and figured by Biitschli and others, figure 20. Nor is it
questioned apparently, that the envelope is ectoplasmic. Even
]\Iinchin, partial as he always is toward cliromatin, does not re-
fuse to admit this. But his way of describing the flagellum is
highly interesting. "A flagellum consists in an elastic axial core
enclosed in a contractile sheath or envelope. . . . The flag-
ellum takes origin from a more or less deeply-seated granule, the
blepharoplast, or basal granule, which will be described in deal-

Evidence from Protozoans 371

ing with the nuclear apparatus. Tlie elastic axis, arising from
the blepliaroplast, can be regarded as a form-determining ele-
ment of endoplasmic origin, the sheath as an ectoplasmic motor
substance." *

As this statement illustrates both the factual point with
which we are concerned and the perverting influence of elemen-
talist theory on supposedly straightforward description, let us
examine it. If a flagellum is composed of a core enclosed in

V

/--c.p.

\-ax.

w

FIGURE 20. II-AC.DMUM OF EUGLEXA (aFTER BfTSCHLl).

ax., axial filament, c.p., contractile protoplasm enveloping the axial
filament, e.p., end piece of the flagellum. r., root of the flagelluin
passing into the liody.

*

a sheath, what justification is there for saying that the organ
arises from a basal granule ? According to the clear implica-
tion contained in the latter part of the statement, only the axial
core arises from this source. And if the statement be correct,
as it undoubtedly is, that the sheath is ectoplasmic, what occasion
is there for throwing into the definition the purely hypothetical
notion that the elastic axis is a "form-determining element"?
In view of the fact that there is as much observational ground
for supposing the sheath to be "form-determining" as there is
for supposing the axial core to be so, either both parts should

372 The Unity of the Organism

be mentioned if a guess about form-determination is to be made,
or neither should be. The consensus of view among authorities
that flagella are either ectoplasmic or endoplasmic structures
ought to be a sufficient refutation of the speculation that the
basal granule, whatever its source, is the "form-determiner" of
the organs ; but when an erroneous speculation has become an
imperative idea, as the chromatin hypothesis seems to have
become for some biologists, nothing seems to suffice short of
going through the operation of killing it time after time even
though it has been dead for many months.

The truth is that if we speculate about "form-determination"
of flagella, and do so on the basis of the objective evidence, we
have to recognize that in some cases neither axial core nor
blepharoplast can be the determiner for the sufficient reason
that no such structures exist. For example, Patton has shown
conclusively that in the species he studied the flagellum arises
from the cytoplasm of the cell quite independently of both the
nucleus and the blepharoplast. "The flagellum, about 40 in
length, consists of a single stout filament whicli arises from
the achromatic space just anterior to the blepharoplast and
passes out of the anterior end. The intracellular portion does
not differ in structure from the remainder and it has no basal
granule in connection with it." ^ The absence of the axial core
in this animal is emphasized as follows: "It is important to note
that the flagellum under a high magnification consists of a
single thick filament and not of a number bound together." ^
This case is especially convincing in that although technical
methods were used that are held to be specially trustworthy for
differentiating chromatic material, so that the nucleus with its
chromosomes and the blepharoplast were brought out sharply
against the surrounding faintly stained cytoplasm, the beginning
of the flagellum in the less deeply stained part of the cell was
clearly recognizable.

The importance of the main issue here is so great as to
justify my repeating what I have said many times. The
central question is not whether there may be a granule (or
some other substance not made visible by the methods used)
which may be form-determining for the flagellum, but
whether we shall refuse to accept the observational evidence
thg\,t the achromatic substance contributes, at least, to the

Emdence from Protozoans 57B

origin of the organ. In otlicr words, the question is, are we
going to reject the positive evidence we actually have, in
the interest of a pure speculation? Even should further
study find that, contrary to Patton's obsei*vations, there is
a granule at the base of the flagellum of Herpetomonas
lygaei which gives rise to an axial core, the observation that
the achromatic substance of the cell participates in the
formation of the flagellum would not be set aside thereby.

{(I) J'ario2is Organs of Sfylonychia and Paramecium

In the chapter on the an;itomy of the protozoa we took
Stylonychia as an example of the high degree of specialization
and integration which the sensory-locomotor system may reach
in a one-celled animal. While the ontogeny of this genus has not
been studied as fully as is desirable^ yet the combined knowledge
we have of its structure and regeneration is sufficient to leave
no room for doubt that the ectoplasm and the outer strata of
endoplasm take an active part in producing the elaborate sensory
and motor organs. For example^ the basal fibers {h. f., figure 6)
are shown by Maier to be attached to the basal edge of the
membranellae and to run inward in the endoplasm, where they
gradually taper to very fine endings not connected with either
the macronucleus or micronuclei or granules of any kind. The
inference seems unescapable tliat ontegenetically at least they
arise in the ectoplasm and grow inward. Again, as to the ecto-
plasm itself, Maier points out that in some parts of the animal
this is laid off into definite areas, each one of which is deeply
cupped outwardly and bears a cilium with its basal granule at
its center. This disposition is specially clear in Paramecium
cauda-ium. To suppose that such a differentiation of the ecto-
plasm is due to the "influence" of the basal granule, the ectoplasm
itself being passively moulded, would be so gratuitous that
probably no biologist would be bold enough to make it definitely ;
yet exactly that assumjDtion would be necessary were "form-
determination" to be denied to everything but chromatin.

Only one other developmental' point can be noticed in connec-
tion with Stylo7iy cilia, that concerning the production of the un-
dulating membrane {m h p., figure 6). That this organ be-
longs to the ectoplasm is generally recognized, and the considera-

374

The Unity of the Organism

tions advanced in favor of the view that it is partly determined
by the ectoplasm^ are essentially the same as those for the view
that the flagella arc thus produced. The particular point to which
attention is now called is the view held by Maier^ and apparently
well supported by observations, that the membrane is the result
of a fusion of a row of cilia. The evidence for this is the
cross-striation of the membrane and the presence of a row of
thickly set, darkly staining granules at its base. If this sup-
position is correct the question arises, where is the "seat" of the
developmental tendency which brings .about the fusion of the

acK-.

b

Kv

nmv

11
d

FIGURE 21. FROXTOXIA I.EUCAS, TRICTIOCYST (aFTER TOXXTGEs).

ach., axial rod. achr., achromatinic substance, h., head,
nni.,^ nuclear membrane.

-n.

n., neck.

cilia? Is it the basal granules or some other elements aside from
the material of the cilia themselves? Or is it ])roduced, as Maier
says, by an "adherence of the neighboring cilia through a plas-
matic substance"? Obviously tliere can be but one answer if it
is to be based on the observational evidence.

Let us now return to the development of the trichocysts of
Frontonia which we partly examined in the last section (figure 15,
p. S27) . That the chromatin of the macronucleus contributes di-
rectly to the organs was shown in 'the section dealing with the di-
rect evidence that cliromatin mav be "hereditary substance." But
it was there stated that the cliromatin was not alone concerned in
their production. Now we must instruct ourselves as to what

Evidence from Protozoans 375

besides chromatin enters into their production. Tlie following
paragrapli from Tonniges tells the story in outline. "Trichocysts
in the act of origination whicli I have designated as trichochro-
midia, i)resent two substances. One is intensely colored with
the nuclear staining medium employed (ach, figure 21), so must
be regarded as chromatin. The other remains uncolored and con-
sequently is held to be achromatic substance {achr, figure 21).
The first produces the axial rod of the future trichocyst, while
the latter, the achromatic substance, produces the external en-
velope and the myoneme-like structure. "♦" Four stages in the de-
velopment of a trichocyst are shown in figure 21 a, b, c, d. Natur-
ally many detailed structural changes not here noticed in both
the axial part and the enveloping part occur before the organ is
completed and ready for use. But these need not concern us
since they in no way affect the main point, namely that evi-
dence that the achromatic substance of the macronucleus is
the physical basis of heredity of organs under consideration,
comes from exactly the same source and is exactly as valid as
is the evidence that chromatin plays such a role.

The question of whether the cytoplasm of the animal plays
a direct part in the development of these organs, while very
important were we seeking for an adequate general theory
of development or for complete knowledge of the factors
involved in this particular development, must not detain
us since all we are concerned with in this section is to find
whether any substances other than chromatin are deter-
miners of hereditary attributes.

(e) The Skeleton of Radiolaria

With these illustrations from the infusoria of sub-
stances other than chromatin which sem^e as the physical
basis of heredity, w^e must turn from the endless examples
that might be drawn from the same group, and pass to
another great sub-division of the protozoa, the Radfolaria,
for a few illustrations. In the chapter on the general
ontogeny of the protozoa we spoke particularly of Hacker's
studies on the development of the skeleton in the Aulo-

376

The Unity of the Organism

spheridae. We will now look a little further into the devel-
opment of portions of these animals.

Hacker's hypothesis of "directing centers" in some of
these animals is particularly interesting for us. What the
general purport of the hypothesis is can be readily under-

S » « 0 . , . • J

/?^i^ \\\\S iVv^^SX ■■■■

.'■'.■. J . '■ ' \ '' ; ■ . \ • • ^

'■/{ ; ■^'"'' ' c. cap.

FIGURE 22. ATJLOSPHAERA (aFTER HAECKER).

c.cap., central capsule.

stood by the help of figures 22 and 23. The skeleton of the
genus here represented is a "lattice-sphere," in Hacker's
terminology, consisting of a network of tubes joining one
another in such a way that six pieces unite at each nodal
point. This scheme makes each mesh of the net a triangle.
A radial piece or spine bearing short branches arises from
each nodal point. The lumen of the tubes contains a gela-

FIGURE 23. AULOSPHAERA ELEGANTISSIMA ( AFTER HAECKEr). DETAIL OF
STRUCTURE.

FIGURE 24. AULOCEROS ( AFTER HAECKER ) . DETAIL SECTION OF SPIKE

a., lumen of shaft ak., axial canal, h., vesicular enlargement of
axial canal at forking of spine, k., secondary silicification. m,
membrane. . ' '

377

'378 Tlic Unity of the Organism

ilnous material and in the center a fine axial filament. As
shown in figure 24, the tubes and the radial pieces are not
in uninterrupted continuity at the nodal points but meet
one another in a common joint.

The entire skeleton is embedded in the extra-capsular sub-
stance, and the central capsule, figure 22, c. cap., contain-
ing the nucleus is, as in most Radiolaria, relatively quite
small. The pattern of the skeletal net Hacker conceives
to be determined by "directing centers," one for each of
the nodal points.

This conception is, as Hacker fully recognizes, purely
hypothetical, and consequently ought not, in the strict
letter of the formulation, to be made much of. Nevertheless
certain of the facts call for something of the sort, if an
explanation of the peculiar skeletal features in accordance
with the principles of heredity is insisted upon. The follow-
ing quotation brings out the most salient of these facts : "In
the stereometric 'dissimilarity' which may exist between the
external body- and skeletal-form and the shape of the cen-
tral capsule ... it is difficult to imagine that the locations
of the nodal points, especiall}^ in the regular triangular
and quadrangular conditions, are determined (projected
outward) by the nucleus. Rather one ought to think here
of distributing and arranging processes which have their
seat in the external layers of the sarcode body itself and
are conditioned either by the competition {Konkurrenz-
kampf) of the pseudopodia or by the interplay of 'spheres
of attraction.'" (Hacker's Monograph, Lief. 3, p. 627.)

Whether "directing centers" are the right things to conceive
as "explaining" such a skeleton as that before us may be ques-
tioned; but I do not see how it is rationalh^ possible to avoid
believing that the main seat of the forces at work is in the
extra-capsular part of the animal, as Hacker says, and not in
the nucleus, and that these forces are hereditary forces. And
such belief is the more unescapable by the facts that, as Hacker

Evidence from Protozoans

379

points out, skeletal production is no mere matter of simple secre-
tion, or still less of crystallization, but of genuine organic growth,
as a detailed study of the completed structure and histogenesis
of the parts shows ; and by the further fact that the parts con-
cerned present characteristic differences for the different species.
Thus in the genus Aiilosphaera to which belongs the species we
have taken as an example, Haeckel recognized twenty-one spe-

---a>sp.

--c.ca-p.

rt.

FIGUUE 25. AULACAXTHA (aFTER BORGERt).

as'p., astropyle. c.cap., central capsule.

c

n., nucleus.

cies. Hacker re-examined about a third of these and added four
new ones. And the specific distinctions are furnished largely
in skeletal details.

(f ) Openings in the Central Capsule of the Radiolaria

, *

Along with these facts of skeletal development may be
considered the development of the openings of the central

380 The Unity of the Organism

capsule. A. Borgert, in particular, has recently investi-
gated this, subject. These openings, known as astropyles,
as'p, figure 25, a, b, c, and parapyles, are characteristic
organs of many Radiolaria. They are the communications
between the body substances situated inside and outside of
the central capsule. Borgert had shown in an earlier paper
that when fission of the animal takes place new parapyles
arise de novo, and not by division of the original organs.

In the memoir now before us he confirms his former obser-
vation on the origin of the parapyles and shows that new
astropyles arise by division of the old. The chief interest
for us in this later study lies in observations on the relation
of the development of the organs to the behavior of the
nucleus. Besides the indirect or mitotic mode of division
of the nucleus previously studied, Borgert now describes two
other modes, one of which is a peculiarly modified indirect
division, and the other a quite unique performance which he
characterizes as "ruffle-like" (Mmischettenform).^ Into the
details of these modes of division we need not go. Sufficient
for us is it to point out that the great nuclear mass n. fig-
ure 25, consisting of a veritable throng (a thousand or
more) of chromosomes, retains its massed character through
all the division stages. The author lays special emphasis on
the facts that at no time does the nuclear membrane dis-
appear; and that the endoplasm within which the nucleus
is embedded takes no "active part in the process of di-
vision," nor does it undergo "any sort of special structural
change." The division of the astropyle and the origin of
new parapyles are correlated in time with the nuclear divi-
sion; but even this correlation is incomplete. Interestingly
enough, tlie formation of new parapyles is far advanced,
the author says, "when tlie condition of tlie nucleus Indicates
the first beginning of the process of division." And Borgert
remarks : "It appears therefore that the foundation of the
new structure results before tlie beginning of nuclear di-

Evidence from Protozoans

381

vision, i.e., at a time when no sort of visible sign of division
is recognizable anywhere on tlie central capsule." That
the account of the mode of division in this species is essen-

riGURE 26, ACANTIIOMETROX PELLUCIDU3I ( AFTER MOROFF AND STIASNY).

ccap., central capsule, ex.cap,s,, extra-capsular sarcode, m.y., my-
ophrisks. m.y'., migrating myophrisks. p.f., pulling fibers, sp.,
spines.

tially correct can be accepted with more assurance from
the fact that Borgert has studied the mitotic mode of di-
vision in the same animal, so that the description is rigor-
ously comparative.

382 The Unity of the Organism

It seems, therefore, entirely justifiable to extend the
application of Hacker's hypothesis of active developmental
centers for skeletal production in the extra-capsular sar-
code to organ production in the capsular membrane.

In the absence of a systematic investigation of the devel-
opment of the adult Radiolarian from its swarm spores, we
have to be satisfied with such fragments of ontogenetic
knowledge of the group as students have had opportunity to
get. A few years ago Moroff and Stiasny studied at Triest
several developmental aspects of the well-known genus Acan-
thometron, figure 26. Besides their observations on the
complicated multiplication processes which take place in
the central capsule, iuA^olving both the chromatic and achro-
matic substances, and according to the authors, implicating
both macro- and micronuclei as well as merozoites, schizo-
zoites and swarm spores, the attention was also given to the
structure and to certain developmental phenomena of the
extra-capsular parts.

The investigators were able to extend previous knowledge
of the adult extra-capsular parts. The extensions which
especially concern us pertain to the myophrisks m.i/., and
to the system of plasmic fibers (p.f., figure 26) surrounding
the radiating spines (sp) of the skeleton. These fibers were
found to be much more numerous than previously described.
Some of them extend to the distal ends of the spines. "Around
each spine there is grouped a whole system of such fibers,
constituting the sheatli of the spine, which in its form re-
sembles a tent." ^ The individual fibers pass down ihto the
general extra-capsular mass where they anastomose with
others of the same tent and with those of the tents of other
spines. There are about twenty of these tents. The au-
thors believe these fibers to be not merely supporting, as
hitherto supposed, but pulling fibers.

The myophrisks are distinct rod-like bodies arranged in
regular fashion around the spines some distance from the

Evidence from Protozoans 383

tips, togctlicr iiiakijii; a sort of barrel-shaped collar. Tliey
become deeply colored when treated with nuclear stains,
while the fibers above described remain nearly or quite un-
stained. "The myophrisks do not insert, as previously de-
scribed, by their proximal ends into the su])erficial ecto-
plasmic layer, and by their distal ends into the spines, but
lie in the pulling fibers." ^^

The developmental point made out is that the myophrisks
arise from chromatic material lying in the central capsule
and migrate out to their definite positions {m.y' ., figure 26).
The origin takes place, according to the authors, in two
ways. By one method the entire nucleus of a merozoite
transforms into the myophrisk ; by the other, the chromatic
bodies of the macronuclei unite to produce these structures.
Numerous details are given of the development and structure
of the myophrisks which we can not enter into. Enough
is it to recognize the direct part played by chromatic sub-
stance in the production of these bodies.

Now comes the point which specially concerns the pres-
ent discussion: The authors believe, from observations of
their own, that Richard Hertwig's supposition that the
bodies are contractile, is correct. Assuming this to be their
office, and assuming the authors to be right in their account
of the relation of the bodies to the pulling fibers and of the
fibers to the spines, we have here a composite apparatus
consisting of the spine, the pulling fibers, and the contrac-
tile elements, one portion of which, the contractile, is de-
rived from chromatic substance, and two portions, the spine
and the pulling fibers, are derived from non-chromatic sub-
stance. A slight reservation must be made in the part of
this statement which concerns the spine and the fibers in
that we are without direct observational knowledge as to
the oHgin of the spines and the fibers. However, it is almost
certain that the fibers are entirely differentiations of extra- .
capsular plasm ; and that the spines are at least partly of

,r s 0

•/s P

\ \ '■-.

B

I'UiURE 27. KUGLYPHA Al,VE()r,ATA, DIVISION STAGES (aF'I'ER MINCIIIn),

N., nucleus, b., daugliter-cell. p.s., pseudopodia. c.v., contractile
vacuole, f., food materials, s.p., shell plates, r.s.p., reserve shell
plates, s'., reserve shell jilates moving into position on daughter-cell.

384

Evidence from Protozoans 385

like origin.

So here again, as in the flagella of various flagellates, and
the trichocysts of Frontonia, we find both chromatic and
non-chromatic substances of the cell acting as the physical
basis of heredity.

(g) The Shells of Foraminifera

Some of the most striking examples of what may be called
general cytoplasmic activity in the production of heredity
structures are furnished by many of the shell-forming Fora-
minifera. The case of Euglypha alveolata may be taken
as illustrative. I take this animal not only because its re-
production is a telling case in favor of my general conten-
tion, but also because it is often used in text-books and
other general zoological works, and so is readily available
for study so far as literature is concerned. As shown by
figure 27 a, b, c, d, e, the animal is egg-shaped, of regular
outline, and enclosed, except for an opening at the small
end, in a thin shell made up of little plates. The plates
are silicious and are glued by a substance supposed to be
silicious. The mode of reproduction exhibited is usually
considered to be a form of budding. By examining the fig-
ures in connection with the following description taken from
Calkins, the points of chief interest will be readily seen.
"This bud (b) grows until it has reached its definitive size
(usually about that of the original cell) when the shell-
coating for the new individual s is deposited. The build-
ing material for the shell of the daughter-individual is
formed within the protoplasm of the maternal cell {r.s.p.).
If regular plates of silica or chitin, these plates are secreted
long before division and stored up in the protoplasm which
surrounds the nucleus {Euglypha, Quadrula). If quartz
crystals, or any other foreign bodies, these particles are
picked up and stored in similar manner, to be used later for

386 The Unity of the Organism

the test of the daughter-cell. When the bud has reached a
certain size, the plates or particles which are to form the
shell move out through the mouth-opening of the parent
shell and forai around the protoplasm of the bud. In the
meantime the nucleus (N) undergoes division, and, in the
case of Euglypha at least, the daughter-nucleus is the last
element to leave the parent organism." ^^

Assuming this account to be essentially correct — and
there seems no reason to doubt that it is — can any candid
person refuse to believe that the protoplasm is at least in
part the actual cause of its own extrusion from the mouth-
opening of the shell, of the production of the plates (in
species in which these are secreted), of transporting them
to their final position, and of arranging them into the shell
of the new individual .^^ And can any one refuse to admit
that the whole formative process is a manifestation of
heredity .P But if one admits these contentions he perforce
admits that the cytoplasm is a physical basis of heredity
if any substance at all can be properly so considered.

(Ji) The Clinging Organs of Sporozoa

The Sporozoa being poor in organs of locomotion and of
contact with the external world, in comparison with the
higher Ciliata, Flagellata and Radiolaria, afford less op-
portunity than these latter for studying the participation
of different substances of the body in organ production.
However, the differentiation of the body into segments in
many species, and the appearance of anchoring spines and
hooks by which the creatures cling to their hosts, make them
favorable for such studies. The developmental stages of
Fyamiia mobuszi shown in figures 28 a, b, c, should be re-
called, as should also the question whether the probability
that the root-like epimerite ep'm which penetrates deep
into the host c^ll, is "determined" largely if not wholly by

Evidence from Protozoans

387

the cytoplasm of tlie cell, as observation indicates. While
the development is in progress the nucleus with its membrane,
chromatin mass and nuclear sap appears to remain intact
and holds its place in the deutomerite far removed from
the developmental changes under consideration. It is not

ep.C,

m^

^s&

mm

n*

e-ptw-

^--etJi^.

?^U?#J

i

FIGURE i28. DEVELOP31EXT OF PYXIXIA MOBUSZI (afTER LEGER AND DUBOSCl).

ep.c, epithelial cell, ep'm., epimerite. n., nucleus.

impossible, indeed not improbable, that future investigation
will find that the nucleus is not so passive during this devel-
opment as the account here given indicates. Chromatin
granules may be proved to escape into the cytoplasm and
possibly to migrate to the region of developmental activity.
But supposing all this should be proved, there still would
remain the fundamental query : would such observation prove

■<>0\

■^j

••'9A

^1

FIGURE 29, EPIMERITE OF PILEOCEPHALUS HEERII (aFTER LANKESTER).

FIGURE 30. EP13IER1TE OF GENEIORHYNCHUS MONNIERI ( AFTER LANKESTER ),

FIGURE 31. EPIMERITE OF ECHINOMERA HISPIDA (aFTER LAKKESTER).

38S

Evidence from Protozoans

389

that the transforming cytoplasmic substance is not actively
participating in the transformation? After what has been
said in the preceding pages, the reader will not doubt what

FIOtTlE 32. EPIMERITE OF BELOIDES FIRMUS ( AFTER LAKKESTER).

the author's reply is to this query. The activity of the nu-
cleus would furnish no evidence whatever for a denial.
As bearing on the question of whether the development

FIGURE 33. EPIMERITE OF COMELOIDES CRINITUS ( AFTER LAKKESTER).

of the epimerite of gregarines can rightly be regarded as
an exhibition of heredity, I present in figures 28 to 32, il-
lustrations of the great variety of form of this organ in

390 The Unity of the Organism

different genera and species of the group. The very es-
sence of the conception of heredity, i.e., resemblance due to
genetic kindred, is obvious in the reappearance of a particu-
lar type of epimerite in every generation of a given species,
while in the group as a whole there is so great a variety of
types.

(i) The ^'Division Center*' of Noctiluca

Thus far in this section we liave been considering the
contribution of non-chromatic substances to the production
of permanent organs in the protozoan body, mostly to or-
gans by which the animals maintain their relation to the
external world. We will now examine a few cases wherein

FIGURE 34. NOCTILUCA MILIARIS ( AFTER HERTWIG).

n., nucleus, o., mouth, f., filament, t., tentacle.

such substances play a leading role in propagation. Per-
haps the most striking example is furnished by the well-
known marine protozoan Noctiluca (figure 34). To state
the point as compactly as possible, division in this animal
is started off and led throughout by a large, dimly staining
body situated in the cytoplasm adjacent to the nucleus. The
division of the nucleus seems to be a process attendant upon,
and probably dependent upon tlie division of this body,
known as the "division center." (Fig. eS5a a.sp.)

■ . .■•-.■■■.•%\No"

......vv-OJ v*/

.:■• /•••!;S=J \ \«

-a.od.

-a.as.

FIGURE 35. FISSION STAGES OF NOCTII.UCA MTLTARIS ( AFTER CALKIXs).

C.S., centrosome. m.f., mantle-fibers, n., nucleus, eh., chromo-
somes, ks., karyosomes. cy., cytoplasm, a.sp. "division center."
c.sp., central spindle, a.as., amphiaster. och., oxychromatin.

391

39^ The Unity of the Organism

Owing to the wide distribution, great abundance, and con-
spicuousness of Noctiluca, it has been a favorite animal for
study at the sea-side during many years, and its mode of
division has proved to be one of the most interesting fea-
tures about the creature. The most important observa-
tions on division in Noctiluca were made by Calkins (figures
35 a, b, c, d, e, taken from the original paper), and a few
quotations from Calkins' writings will set forth the cardinal
facts. "On the outside of the nucleus in Noctiluca, in the
cytoplasm and close against the nuclear membrane, is a
large, faintly staining spherical mass, which acts as a divi-
sion-center. During the early stages of nuclear activity,
the sphere divides into two similar halves, connected by a
strand composed of fibers which are formed from the sub-
stance of the sphere. These fibers compose the central
spindle, and are homologous in every way with the central-
spindle fibers of the usual type of mitosis in Metazoa. The
nucleus then elongates in a direction at right angles to the
central spindle, and at the same time bends in the centre in
such a way that the central spindle sinks into a depression
in the nucleus, which surrounds it upon three sides. In
this way the nuclear plate is finally wrapped about the
central spindle in the form of an incomplete ring. . . .
The nuclear membrane then disappears in that part of the
nucleus which is turned toward the central spindle, while
it is retained unbroken in all other parts of the nucleus.
Thus the chromosomes, as in the higher types, are brought
into contact with the central spindle fibres. They then split
longitudinally, and through the agency of the mantle-fibres
are separated into two equal groups, each group drawn
toward its own daughter-sphere. Within the sphere the
fibres are focussed in a centrosome which, at this period,
can be demonstrated with the greatest ease. The division
is finally completed by the separation of the remainder of
the nucleus and the re-formation of the daughter-nuclei.

Evidence from Protozoans B93

while the chromosomes disintegrate into granules, which
again form the large chromatin reservoirs, characteristic
of Noctiluca.'' ^^

The matters of chief interest for us in this account are
the extra-nuclear position of the division center; its large
size, making the observation of it almost as practicable as
observation of the nucleus itself ; the sharp distinction, in-
dicated by the difference in staining, between the material of
the division center and tlie nuclear contents, particularly
the chromatic part of the contents ; the unmistakably in-
dependent and leading part played by the center in division,
the split chromosomes, for example, being separated
"through the agency of the mantle-fibres," these latter a
part of the sphere ; and finally the strong direct evidence
that the activities of the center pertain to the substance of
the center itself and are not caused entirely by a "force" or
"influence" of the centriole. With reference to the last
point it should be said that Calkins found considerable evi-
dence that the centrioles (centrosomes according to the
nomenclature employed by him) which are easily recogniz-
able in the division center during advanced stages of nuclear
division, are in the nucleus during the resting period and
only migrate into the center during the divisional activity
of the center and the nucleus. But granting to this minute
granule all that actual observation entitles it to, the most
that can be said is, that it is an active participant in the
complex series of changes and transformations which con-
stitute the propagation-division of the animal. Calkins'
statement that "A cytoplasmic substance, corresponding to
the centrosphere of many metazoan cells, is invariably pres-
ent. It is a permanent organ of the cell, often as large, or
larger, than the nucleus ; it divides to form an amphiaster,
consisting of two asters with connecting mantle-fibres, the
central-spindle," ^^ should be taken at its face value. What
I mean by this is that we have no right to pin our faith to

394 The Unity of the Organism

a speculative view based on something other than evidence
contained in this particular statement, that would eviscer-
ate this statement of its essential meaning. And such would
be the effect were one to speculate that the centriole is
"generative chromatin" and so the causal explanation of
the phenomena presented by the center. The "cytoplasmic
substance" which, Calkins says, constitutes the central
sphere, is a "physical basis of heredity." It is such because
it does that by which, and by which alone, any substance
can be proved to be a physical basis of heredity. It takes
a direct, active part in a series of structural transforma-
tions "to form an amphiaster, consisting of two asters with
connecting mantle-fibres," that closely resemble one another
in many individual animals genetically related and consti-
tuting the species NoctUuca miliaris (figure 34.)

(j) The Centrosphere of Protozoa Generally

We must carry a little further the examination of the
centrosphere, or division center, as itself a physical basis
of heredity. The wide occurrence among the protozoa of a
body, or at any rate of substance, which does not stain
readily and hence is not chromatin, but which plays a funda-
mental part in cell division, seems to be recognized by all
students of these animals. As we are now concerned with the
question of how general in the group as a whole is the ac-
tive participation of this achromatic substance in propa-
gation, a summarized account of what is known on the sub-
ject will meet our purposes.

Since, as has been previously pointed out, Minchin is a
strong chromatinist, we shall be safe from bias in the other
direction if we rely chiefly on his late book for the account.
Speaking broadly, protozoologists recognize two types or
classes of achromatic substance, dependent upon its loca-
tion in the cell. In one class, of which NoctUuca is an ex-

Evidence from Protozoavs 395

ample, it is outside the nucleus ; in the otlier class it is in-
side the nucleus. . As an example of the first, several helio-
zoans ma}^ be mentioned, notably Acanthocysiis and Sphae-
rastrum; and as exam])les of the latter, several species of
Coccidium, belonging to the Sporozoa, Eiiglesia, a flagellate,
and Arcella, a sarcodinian. Then there are combinations
and intermediate states between the two types. The fol-
lowing quotations from Minchin's book not only indicate this,
but bear directly on our main point. "A most instructive
series, showing how extranuclear elements come to collab-
orate in the mechanism of division, is furnished by some
examples of the Heliozoa, and especially by the nuclear di-
visions of Actinosphaerium, which have been the subject of
extraordinarily thorough investigation by Hertwig. ... In
the ordinary karyokinesis of Actinosphaerium an equatorial
plate is formed, composed of a large number of small, rod-
like chromosomes, imperfectly separated from one another,
which divide transversely. The spindle arises from the
achromatinic framework of the nucleus, and terminates in
two conspicuous polar plates lying within the persistent
membrane. External to the membrane are two large conical
masses of archoplasm, termed the *polar cones.' " ^^ In a
word, three distinct substances are here observed in col-
laboration: two, the chromatic bodies and the achromatinic
framework, being intra-nuclear ; and one, the archoplasmic
cone, being extra-nuclear. The observations indicate that
the archoplasmic substance is a less active collaborator in
the division than are the other two substances. But, pass-
ing to another species, "In Actimophrys the karyokinesis ap-
pears to be of a type similar to that of Actinosphaermm^
with persistent membrane, but with more activity in the
extra-nuclear archoplasmic elements."

And finally, relative to the degree and character of the
collaboration of the various elements: "In Acanthocystis,
however, the nuclear membrane disappears completely from

S96 The Unity of the Organism

the karyokinetic figure, and it is no longer possible, in con-
sequence, to distinguish the parts of the achromatic spindle
which are of intra nuclear and extra nuclear origin re-
spectively. Nuclear and cytoplasmic elements are in com-
plete cooperation." ^^

Minchin's reference to the researches of Hertwig on the
Heliozoa, indicated in the above quotation, makes this an
appropriate place to call attention to the great interest,
from our standpoint, which attaches to Hertwig's denial of
Absolute Power of the nucleus in the life of the cell, as in-
dicated by his well-known theory of nuclear-protoplasmic
relation. Recognizing the great weight of the views of this
investigator as touching the main issue here does not neces-
sarily commit us one way or the other as to all the details
of the "nucleo-plasmic relation" hypothesis.

The reader's attention is called again to the argument
that the morphological elements and the activities displayed
in this reproduction are in themselves manifestations of
heredity, based on the fact that they pertain to different
though rather closely related species of animals, each one
of which presents its own particular type of the phenomena.
Actiiiosphaeriuin and Actinophrys are closely related gen-
era, among the differential attributes of which is this very
matter of difference in the structure and relations and ac-
tivities of the various elements collaborating in their propa-
gation. Each genus is true to its type in these attributes
as well as in others. How then is it possible, consistency
and fair dealing being assumed to be cardinal virtues of
science, to refuse to recognize that not only the behavior of
the chromosomes in the two cases, but likewise that of the
achromatinic framework and the archoplasmic bodies, are
themselires manifestations of heredity, and that the substance
of each in the initial stage of the series is a "physical basis
of heredity?"

Evidence from Protozoans 397

Concluding Remark on Evidence Presented

Our objective study of the production of hereditary
structures and activities in the protozoa may well end with
a comment on a paragraph occurring in one of Calkins' able
and useful pa^jers. In the general conclusions of this paper
wc read: "The chromatin, in addition to being the I'ecog-
nized agent in heredity, is also generally recognized as the
center of formative changes in the ordinary vegetative ac-
tivities of cell life. Recent observations have been inter-
preted to show that it is the seat of oxidative processes and
the direct agent in metabolism. These various supposed
functions of the chromatin are, in large part, inferential,
and there are no observations to show whether it alone is
the center of these various activities, or whether it plays
the part of middleman in the cell. I do not know whether
it is possible to determine such a point." ^^

I ask the reader to note attentively this group of state-
ments. According to the opening words chromatin is "the
recognized agent in heredity," while according to the last
sentence not only is such a role of the chromatin "largely
inferential" and there are "no obsei'A'ations to show" that
"it alone is the center" of such activity, but the author
frankly admits himself in doubt as to the possibility of de-
termining such a point.

What I chiefly wish to do in connection with this is to
insist that such facts as we have just been examining, some
of which were discovered by Calkins himself, relative to the
participation of non-chromatic parts of the cell in the
ontogeny of many protozoans, are, according to my inter-
pretation, conclusive evidence that chromatin is not alone
the "center" of activity of hereditary development. For
the rest I do no more in this chapter than call attention
to the fact that further discussion of the matter at issue is
not biological in a- strict sense, but is part of the problem

398

The Unity of the Organism

of the validity of observational knowledge and the nature
of suppositions and of inferences.

REFERENCE INDEX

1. Johnson 512

2. Johnson 518

3. Miislow 36T

4. Minchen 52

5. Patton 8

6. Patton 7

7. Tonniges 330

8. Borgert 155

9. Morolf 211

10. Moroff 212

11. Calkins ('10) 93

12. Calkins ('10) 266

13. Calkins ('99) 757

14. Minchin 114

15. Minchin 117

16. Calkins ('03) 230

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