LIFE AND DEATH.

LIFE AND DEATH

BY

A. DASTRE,

I'ROFESSOR or PHYSIOLOGY AT THK SORBONNR.

TRANSLATED BY

W. J. GREENSTREET, M.A., F.R.A.S.

THE WALTER SCOTT PUBLISHING CO, LTD.,

PATERNOSTER SQUARE, LONDON, E.G.

CHARLES SCRIBNER'S SONS,

153-157 Fli-'TH AVENUE, NEW YORIL

1911

PjREFACE.

The educated and inquiring public of the present
day addresses to the experts who have speciah'zed
in every imaginable subject the question that was
asked in olden times of Euclid by King Ptolemy
Philadelphus, Protector of Letters. Recoiling in
dismay from the difficulties presented by the study
of mathematics and annoyed at his slow progress, he
inquired of the celebrated geometer if there was
not some royal road, could he not learn geometry
more easily than by studying the Elements. The
learned Greek replied, " There is no royal road."
These royal roads making every branch of science
accessible to the cultivated mind did not exist in
the days of Ptolemy and Euclid. But they do
exist to-day. These roads form what we call
Scientific Philosophy,

Scientific philosophy opens a path through the
hitherto inextricable medley of natural phenomena.
It throws light on facts, it lays bare principles, it
replaces contingent details by essential facts. And
thus it makes science accessible and communicable.
Intellectually it performs a very lofty function.

There is virtually a philosophy of every science,
v

VI PREFACE.

There is therefore a philosophy of the science which
deals with the phenomena of life and death — i.e., of
physiology. I have endeavoured to give a summary
of this philosophy in this volume. I have had in
view two classes of readers. In the first place there
are readers of general culture who are desirous of
knowing something of the trend of ideas in biology.
They already form quite a large section of the great
public.

These scholars and inquirers, with Bacon, believe
that the only science is general science. What they
want to know is not what instruments we use, our
processes, our technique, and the thousand and one
details of the experiments on which we spend our
lives in the laboratory. What they are interested in
are the general truths we have acquired, the pro-
blems we are trying to solve, the principles of
our methods, the progress of our science in the
past, its state in the present, its probable course in
the future.

But I venture to think that this book is also
addressed to another class of readers, to those whose
professional study is physiology. To them it is
dedicated. They have been initiated into the
mysteries of the science. They are learning it by
practice. That is the right method. Practice makes
perfect. Claude Bernard used to say that in order
to be an expert in experimental science you must
first be " a laboratory rat." And among us there are
many such "laboratory rats." They are guided in

PREFACE. Vll

the daily task of investigation by a dim instinct
of the path and of the direction of contemporary
physiology. Perhaps it may be of assistance to
them to find their more or less unconscious ideas
here expressed in an explicit form.

A. DASTRE.

CONTENTS.

BOOK I.

The Frontiers of Science. General Theories of
Life and Death. Their Successive Trans-
formations.

CHAP. PAGE

I. Early Theories i

II. Animism - 5

III. Vitalism 15

IV. The Monistic Theory 34

V. The Emancipation of Scientific Research from

THE Yoke of Philosophical Doctrine . . 42

BOOK II.

The Doctrine of Energy and the Living World.
General Ideas of Life. Alimentary Life.

1. Energy in General 57

II. Energy in Biology . . . . . . -97

III. Alimentary Energetics 116

BOOK III.

The Characters Common to Living Beings.

I. Doctrine of Vital Unity 146

II. Morphological Unity of Living Beings. . . 157

III. Chemical Unity of Living Beings . . . -173

IV. Twofold Conditioning of Vital Phenomena.

Irritability 188

ix

X CONTENTS.

CHAP. PAGE

V. The Specific Form: its Acquisition, its Repara-
tion - 199

VI. Nutrition. Functional Assimilation. Functional

Distribution. Assimilating Synthesis . . 209

BOOK IV.

The Life of Matter.

I. Universal Life (Opinions of the Philosophers
AND Poets). Continuity between Brute Bodies
and Living Bodies. Origin of the Principle of

Continuity 239

IL Origin of Living Matter in Brute Matter . . 249
in. Organization and Chemical Composition of Living

Matter and Brute Matter ..... 255

IV. Evolution and Mutability of Living Matter and

Brute Matter ........ 259

V, The Composition of the Specific Form. Living

Bodies and Crystals. Cicatrization . . .281
VI. Nutrition in the Living Being and in the

Crystai 290

VII. Generation in Brute Bodies and Living Bodies.

Spontaneous Generation 294

BOOK V.

Senescence and Death.
I. The Different Points of View from which Death

MAY BE regarded 307

II. Constitution of the Organisms. Partial Death.

Collective Deaths 312

III. Physical and Chemical Characteristics of

Cellular Deaths. Necrobiosis .... 321

IV. Apparent Perennity of Complex Individuals . 330
V. Immortality of the Protozoa and of Slightly

Differentiated Cells 334

V^I. Lethality of the Metazoa and of Differentiated

Cells ......... 340

VII. Man. The Instinct of Life and the Instinct of

Death 345

Index 361

LIFE AND DEATH.

BOOK I.

THE FRONTIERS OF SCIENCE — GENERAL THEORIES
OF LIFE AND DEATH — THEIR SUCCESSIVE
TRANSFORMATIONS.

Chapter I. Early Theories. — II. Animism. — III. Vitalism. —
IV. Monism. — V. Emancipation of Scientific Research
from the Yoke of Philosophy.

CHAPTER I.

EARLY THEORIES.

Animism — Vitalism — The Physico-Chemical Theory — Their
Survival and Transformations.

The fundamental theories of science are but the ex-
pression of its most general results. What, then, is
the most general result of the development of
physiology or biology — that is to say, of that depart-
ment of science which has life as its object ? What
glimpse do we get of the fruit of all our efforts ? The
answer is evidently the response to that essential
question — What is Life ?

There are beings which we call living beings ; there
are bodies which have never been alive — inanimate
bodies ; and there are bodies which are no longer

I

2 LIFE AND DEATH.

alive — dead bodies. The fact that we use these terms
impHes the idea of a common attribute, of a quid pro-
itriunty life, which exists in the first, has never existed
in the second, and has ceased to exist in the last. Is
this idea correct ? Suppose for a moment that this
is so, that this implicit supposition has a foundation,
and that there really is something which corresponds
to the word " life." Must we then wait for the last
days of physiology, and in a measure for its last
word before we know what is hidden behind this
word, " life " ?

Yes, no doubt positive science should be precluded
from dealing with questions of this kind, which are
far too general. It should be limited to the study of
second causes. But, as a matter of fact, scientific
men in no age have entirely conformed to this pro-
visional or definitive antagonism. As the human
mind cannot rest satisfied with indefinite attempts, or
with ignorance pure and simple, it has always asked,
and even now asks, from the spirit of system the
solution which science refuses. It appeals to philo-
sophical speculation. Now, philosophy, in order to
explain life and death, offers us hypotheses. It offers
us the hypotheses of thirty, of a hundred, or two
thousand years ago. It offers us animism ; vitalism
in its two forms, unitary vitalism or the doctrine of
vital force, and dismembered vitalism or the doctrine
of vital properties ; and finally, materialism, a
mechanical theory, unicism or monism, — to give it
all its names — i.e., the physico-chemical doctrine of
life. There are, therefore, at the present day, in
biology, representatives of these three systems which
have never agreed on the explanation of vital
phenomena — namely, animists, vitalists, and monisLs.

EARLY THEORIES. 3

But it is pretty clear that there must have been
some change between yesterday and to-day. Not
in vain has general science and biology itself made
the progress which we know has been m^de since
the Renaissance, and especially during the course
of the nineteenth century. The old theories have
been compelled to take new shape, such parts as have
become obsolete have been cut away, another
language is spoken — in a word, the theories have
become rejuvenated. The neo-animists of our day,
Chauffard in 1878, von Bunge in 1889, and more
recently Rindfleisch, do not hold exactly the same
views as Aristotle, St. Thomas Aquinas, or Stahl.
Contemporary neo-vitalists, physiologists like Heiden-
hain, chemists like Armand Gautier, or botanists like
Reinke do not between 1880 and 1900 hold the same
views as Paracelsus in the fifteenth century and Van
Helmont in the seventeenth, as Barthez and Bordeu at
the end of the eighteenth, or as Cuvier and Bichat at
the beginning of the nineteenth century. Finally, the
mechanicians themselves, whether they be disciples
of Darwin and Haeckel, as most biologists of our
own time, or disciples of Lavoisier, as most physio-
logists of the present day, have passed far beyond the
ideas of Descartes. They would reject the coarse
materialism of the celebrated philosopher. They
would no longer consider the living organism as a
machine, composed of nothing but wheels, springs,
levers, presses, sieves, pipes, and valves ; or again
of matrasses, retorts, or alembics, as the iatro-
mechanicians and would-be chemists of other days
believed.

All that is changed, at any rate in form. If we look
back only thirty or forty years we see that the old

4 LIFE AND DEATH.

doctrines have undergone more or less profound
modifications. The changes of form, which have been
made necessary by the acquisitions of contemporary
science, enable us to appreciate its progress. They
enable us to give an account of the progress of
biology, and for this reason they deserve to be
examined with some attention. It is into this
examination that I ask my readers to accompany me.

CHAPTER 11.

ANIMISM.

The Common Characteristic of Animism and Vitalism : the
Human Statue — Primitive Animism — Stahl's Animism —
First Objection with Reference to the Relation between
Soul and Body — Second Objection : the Unconscious
Character of Vital Operations — Twofold Modality of the
Soul — Continuity of the Soul and Life.

Children are taught that there are three kingdoms
in Nature — the mineral kingdom and the two Hving
kingdoms, animal and vegetable. This is the whole
of the sensible world. Then above all that is placed
the world of the soul. School-boys therefore have
no doubts on the doctrines that we discuss here.
They have the solution. To them there are three
distinct spheres, three separate worlds — matter, life,
and thought.

It is this preconceived idea that we are about to
examine. Current opinion solves a priori the question
of the fundamental homogeneity or lack of resem-
blance of these three orders of phenomena — the
phenomena of inanimate nature, of living nature, and
of the thinking soul. Aniviism, vitalis^n, and monism
are, in reality, different ways of looking at them.
They are the different answers to this question : —
Are vital, psychic, and physico-chemical manifesta-
tions essentially distinct? Vitalists distinguish be-

5

5 LIFE AND DEATH.

tween life and thought, animists identify them. In
the opposite camp mechanicians, materiah'sts, or
monists make the same mistake as the animists, but
to that mistake they add another : they assimilate the
forces at play in animals and plants to the general
forces of the universe ; they confuse all three — soul,
life, inanimate nature.

These problems belong on many sides to meta-
physical speculation. They have been discussed by
philosophers ; they have been solved from time im-
memorial in different ways, for reasons and by argu-
ments which it is not our purpose to examine here,
and which, moreover, have not changed. But on
some sides they belong to science, and must be tested
in the light of its progress. Cuvier and Bichat, for
example, considered that the forces in action in
living beings were not only different from physico-
mechanical forces, but were utterly opposed to them.
We now know that this antagonism does not exist.

The preceding doctrines, therefore, depend up to a
certain point on experiment and observation. They
are subject to the test of experiment and observation
in proportion as the latter can give us information on
the degree of difference or analogy presented by
psychic, vital, and physico-chemical facts. Now,
scientific investigations have thrown light on these
points. There is no doubt that the analogies and
the resemblances of these three orders of manifesta-
tions have appeared more and more numerous and
striking as our knowledge has advanced. Hence it is
that animism can count to-day but very few advocates
in biological science. Vitalism in its different forms
counts more supporters, but the great majority have
adopted the physico-chemical theory.

ANIMISM. 7

Both animism and vitalism separate from matter a
directing principle which guides it. At bottom they
are mythological theories somewhat similar to the
paganism of old. The fable of Prometheus or the
story of Pygmalion contains all that is essential.
An immaterial principle, divine, stolen by the
Titan from Jupiter, or obtained from Venus by the
Cypriot sculptor, descends from Olympus and
animates the form, till then inert, which has been
carved in the marble or modelled in the clay. In a
word, there is a human statue. It receives a breath
of heavenly fire, a vital force, a divine spark, a soul,
and behold ! it is alive. But this breath can also
leave it. An accident happens, a clot in a vein, a
grain of lead in the brain — the life escapes, and all
that is left is a corpse. A single instant has proved
sufficient to destroy its fascination. This is how all
men picture to their minds the scene of death. The
breath escapes ; something flies away, or flows away
with the blood. The happy genius of the Greeks
conceived a graceful image of this, for they re-
presented the life or the soul in the form of a butter-
fly (Psyche) leaving the body, an ethereal butterfly,
as it were, opening its sapphire wings.
^ But what is this subtle and transient guest of the
human statue, this passing stranger which makes of
the living body an inhabited house? According to
the animists it is the soul itself, in the sense in
which the word is understood by philosophers ; the
immortal and reasoning soul. To the vitalists it is
an inferior, subordinate soul ; a soul, as it were, of
secondary majesty, the vital force, or in a word, life.

Primitive Animism. — Animism is the oldest and
most primitive of the conceptions presented to the

2

» LIFE AND DEATH.

human mind. But in so far as it is a co-ordinated
doctrine, it is the most recent. In fact it only
received its definitive expression in the eighteenth
century, from Stahl, the philosopher-physician and
chemist.

According to Tylor, one of the first speculations of
primitive man, of the savage, is as to the difference
between the living body and the corpse. The former
is an inhabited house, the latter is empty. To such
rudimentary intellects the mysterious inhabitant is a
kind of double or duplicate of the human form. It is
only revealed by the shadow which follows the body
when illuminated by the sun, by the image of its
reflection in the water, by the echo which repeats the
voice. It is only seen in a dream, and the figures
which people and animate our dreams are nothing
but these doubled, impalpable beings. Some savages
believe that at the moment of death the double, or
the soul, takes up its residence in another body.
Sometimes each individual possesses, not one of these
souls, but several. According to Maspero, the
- Egyptians counted at least five, of which the
principle, the ka or double, would be the aeriform or
vaporous image of the living form. Space is peopled
by souls on their travels, which leave one set of bodies
to occupy another set. After having been the cause
of life in the bodies which they animated, they
react from without on other beings, and are the
cause of all sorts of unexpected events. They are
benevolent or malevolent spirits.

Analogy inevitably leads simple minds to extend
the same ideas to animals and plants ; in a word, to
attribute souls to everything alive, souls more or less
nomadic, wandering, or interchangeable, as is taught

ANIMISM. 9

in the doctrine of metempsychosis. Mons. L. Errera
points out that this primitive, co-ordinated, hier-
archized doctrine — meet subject for the poet's art — is
the basis of all ancient mythologies.

The Animism of Stahl. — Modern animism was
much more narrow in scope. It was a medical theory —
ie. almost exclusive to man. Stahl had adopted it
in a kind of reaction against the exaggerations of the
mechanical school of his time. According to him, the
life of the body is due to the intelligent and reason-
ing soul. It governs the corporeal substance and
directs it towards an assigned end. The organs are
its instruments. It acts on them directly, without
intermediaries. It makes the heart beat, the muscles
contract, the glands secrete, and all the organs per-
form their functions. Nay more, it is itself the
architectonic soul, which has constructed and which
maintains the body which it rules. It is the mens
agitat molem of Virgil.

It is remarkable that these ideas, so excessively
and exaggeratedly spiritualistic, should have been
brought forward by a chemist and a physician, while
ideas completely opposed to these were admitted by
philosophers like Descartes and Leibniz, who were
decided believers in the spirituality of the soul. Stahl
had been Professor of Medicine at the University of
Halle, physician to the Duke of Saxe- Weimar, and
later to the King of Prussia. He left an important
medical and chemical work, both theoretical and
practical. He is the author of the celebrated theory
of phlogiston, which held its ground in chemistry up
to the time of Lavoisier. He died about 1734.

Animism survived him for some time, maintained
by the zeal of a few faithful disciples, But after the

10 LIFE AND DEATH.

witty mockery of Bordeu/ in 1742, it began to decay.
We must, however, point out that an attempt to revive
this theory was made in 1878 by a well-known doctor
of the last generation, E. Chauffard. While preserving
the essential features of the theory, this learned
physician proposed to bring it into harmony with
modern science, and to free it from all the reproaches
which had been levelled at it.

The Attimtsin of E. Chauffard. — These reproaches
were numerous. The most serious is of a philosophic
nature. It rises from the difficulty of conceiving a
direct and immediate action of the soul, considered as
a spiritual principle, upon the matter of the body.
There is such an abyss — hewn by the philosophic
mind itself — between soul and body, that it is im-
possible to imagine any relation between them. We
can only get a glimpse of how the soul might become
an instrument of action.

This was the problem which sorely tried the genius
of Leibniz. Descartes, in earlier days, attacked it
vigorously, like an Alexander cutting the Gordian
knot. He separated the soul from the body, and
made of the latter a pure machine in the government
of which the soul had no part. He attributed all the
known manifestations of vital activity to inanimate
forces. Leibniz, also, was compelled to reject all
action, all contact, all direct relation, every real bond
between soul and body, and to imagine between them

1 In a thesis presented in 1742 at Montpellier, Bordeu, then
only twenty years of age, made game of the tasks imposed by
animists on the Soul, "which has to moisten the lips when
required ; " or, " whose anger produces the symptoms of certain
diseases;" or again, "which is prevented by the consequences
of original sin from guiding and directing the body."

ANIMISM. II

a purely metaphysical relation — pre-established har-
mony:— "Soul and body agree in virtue of this
harmony, the harmony pre-established since the
creation, and in no way by a mutual, actual, physical
influence. Everything that takes place in the soul
takes place as if there were no body, and so every-
thing takes place in the body as if there were no
soul." At this point we almost reach a scientific
materialism. It is easy for the materialist to break
this frail tie of pre-established harmony which so
loosely unites body and soul, and to exhibit the
organism as under th-e sole control of universal
mechanics and physics.

Thus the weak point of Stahl's animism was the
supposition of a direct action exercised on the organ-
ism by a distinct, heterogeneous, spiritual principle.

Chauffard has endeavoured to avoid this pitfall. In
conformity with modern ideas, he has brought together
what the ancient philosophers and Stahl himself
separated — the activity of matter and the activity of
the soul. " Thought, action, function, are embraced
in an indissoluble union." This is the classical but
not very lucid theory which has been so often re-
produced— Homo f actus est anima vivens — which
Bossuet has expressed in the celebrated formula :
" Soul and body form a natural whole."

A second objection raised against animism, is that
the soul acts consciously, with reflection, and with
volition, and that its essential attributes are not found
in most physiological phenomena, which, on the con-
trary are automatic, involuntary, and unconscious.
The contradictory nature of these characteristics has
obliged vitalists to conceive of a vital principle
distinct from thought. Chauffard, agreeing here with

12 LIFE AND DEATH.

Boullier, Tissot, and Stahl himself, does not accept
this distinction ; he refuses to shatter the unity of the
vivifying and thinking principle. He prefers to at-
tribute to the soul two modes of action : the one
which is exercised on the acts of thought, and hence
it proceeds consciously, with reflection, and with
volition ; the other exercising control over the physio-
logical phenomena which it governs, " by unconscious
impressions, and by instinctive determinations, obeying
primordial laws." This soul is hardly in keeping with
his definition of a conscious, reflecting, and voluntary
principle; it is a new soul, a somatic soul, singularly
akin to that rachidian soul which, according to
Pfluger, a well-known German physiologist, resides
in each segment of the spinal marrow, and is respon-
sible for reflex movements.

Tivofold Modality of the Soul. — This twofold
modality of the soul, this duality admitted by Stahl
and his disciples, was repugnant to many thinkers,
and it is this repugnance that gave rise to the vitalistic
school. It appeared to them to be a heresy tainted
by materialism — and so it was. In this lay the
strength and the weakness of animism. It admits
of a unique animating principle for all the manifes-
tations of the living being, for the higher facts in the
realm of thought, and for the lower facts connected
with the body. It throws down the barriers which
separate them. It fills up the gap between the
different forms of human activity, and assimilates
them the one to the other.

Now this is precisely what materialism does. It,
too, reduces to a single order the psychical and physi-
ological phenomena, between which it no longer
recognizes anything but a difference of degree.

ANIMISM. 13

thought being only a maximum of the vital move-
ment, or life a minimum of thought. In truth, the
aims of the two schools are diametrically opposed ;
the one claims to raise corporeal activity to the
dignity of thinking activity, and to spiritualize the
vital fact ; the other lowers the former to the level of
the latter and materializes the psychic fact. But,
though the intentions are different, the result is
identical. Spiritualistic monism inclines towards
materialistic monism. One step more, and the soul,
confused with life, will be confused with physical
forces.

On the other hand, twofold modality has this
advantage, that it escapes the objection drawn from
the existence of so many living beings to which a
thinking soul cannot be attributed ; an anencephalous
fcetus, the young of the higher animals, the lower
animals and plants, living without thought, or with a
minimum of real, conscious thought. The advocate
of animism replies that this physiological activity is
still a soul, but one which is barely aware of its
existence — a gleam of consciousness. In this theory,
the knowledge of self, the consciousness, is of all
degrees. On the other hand, in the eyes of the
vitalist, it is an absolute fact which allows of no
attenuation, of no middle course between the being
and the non-being.

It is this conception of the continuity of the soul and
life, it is the affirmation of a possible lowering of the
complete consciousness down to a mere gleam of know-
ledge, and finally down to unconscious vital activity,
which saved animism from complete shipwreck. That
is why this ancient doctrine finds, even in the present
day, a few rare supporters. An able German scientist,

14 LIFE AND DEATH.

G. von Bunge, well known for his researches in physio-
logical chemistry, professes animistic views in a work
which appeared in 1889. He attributes to organized
beings a guiding principle, a kind of vital soul. A
distinguished naturalist, Rindfleisch, of Lubeck, has
likewise taken his place among the advocates of what
we may call neo-animism.

CHAPTER III.

VITALISM,

Its Extreme Forms — Early Vitalism, and Modern Neo-vitalism
— Advantage of distinguishing between Soul and Life —
§ I. The Vitalisvi of Ba7-t}icz — Its Extension — The Seat of
the Vital Principle— The Vital Knot— The Vital Tripod-
Decentralisation of the Vital Principle — § 2. The Doctrine
of Vital Properties — Galen, Van Helmont, Xavier Bichat,
and Cuvier — Vital and Physical Properties antagonistic —
§ 3. Scientific iV(ffl-7///a//j;«— Heidenhain — § 4. Philo-
sophical Neo-vitalism— 'Rtxnkc.

Extreme Forms: Early Vitalism and Modern Neo-
vitalism. — Contemporary neo-vitalism has weakened
primitive vitalism in some important points. The
latter made of the vital fact something quite specific,
irreducible either to the phenomena of general physics
or to those of thought. It absolutely isolated life,
separating it above from the soul, and below from in-
animate matter. This sequestration is nowadays
much less rigorous. On the psychical side the barrier
remains, but it is lowered on the material side. The
neo-vitalists of to-day recognize that the laws of
physics and chemistry are observed within, as well as
without, the living body; the same natural forces
intervene in both, only they are "otherwise directed."

The vital principle of early times was a kind of
anthromorphic, pagan divinity. To Aristotle, this
force, the anima, the Psyche, worked, so to speak, with

15

l6 LIFE AND DEATH.

human hands. According to the well-known ex-
pression, its situation in the human body corresponds
to that of a pilot on a vessel, or to that of a sculptor
or his assistant before the marble or clay. And, in
fact, we have no other clear image of a cause external
to the object. We have no other representation of a
force external to matter than that which is offered by
the craftsman making an object, or in general by the
human being with his activity, free, or supposed to be
free, and directed towards an end to be realized.

Personifications of this kind, the mythological
entities, the imaginary beings, the ontological fictions,
which ever filled the stage in the mind of our pre-
decessors, have definitely disappeared ; no longer have
they a place in the scientific explanations of our time.
The neo-vitalists replace them by the idea of direction^
which is another form of the same idea of finality.
The series of second causes in the living being seems
to be regulated in conformity with a plan, and directed
with a view to carrying it out. The tendency which
exists in every being to carry out this plan, — that is to
say, the tendency towards its end, — gives the impulse
that is necessary to carry it out. Neo-vitalists claim
that vital force directs the phenomena which it does not
produce, and which are in reality carried out by the
general forces of physics and chemistry.

Thus, the directing impulse, considered as really
active, is the last concession of modern vitalism. If
we go further, and if we refuse to the directing idea
executive power and efficient activity, the vital
principle is weakened, and we abandon the doctrine.
We can no longer invoke it. We cease to be vitalists
if the part played by the vital principle is thus far
restricted. At first it was both the author of the

VITALISM. 17

plan and the universal architect of the organic edifice ;
it is now only the architect directing his workmen,
and they arc physical and chemical agents. It is now
reduced to the plan of the work, and even this plan
has no objective existence; it is now only an idea.
It has only a shadow of reality. To this it has been
reduced by certain biologists. For this we may thank
Claude Bernard ; and he has thereby placed himself
outside and beyond the weakest form of vitalism. He
did not consider the idea of direction as a real
principle. The connection of phenomena, their
harmony, their conformity to a plan grasped by the
intellect, their fitness for a purpose known to the
intellect, are to him but a mental necessity, a meta-
physical concept. The plan which is carried out has
only a subjective existence; the directing force has no
efficient virtue, no executive power; it does not
emerge from the intellectual domain in which it took
its rise, and does not " react on the phenomena which
enabled the mind to create it."

It is between these two extreme incarnations of the
vital principle, on the one hand an executive agent, on
the other a simple directing plan, that the motley pro-
cession of vitalist doctrines passes on its way. At the
point of departure we have a vital force, personified,
acting, as we have stated, as if with human hands
fashioning obedient matter; this is the pure and
primitive form of the theory. At the other extreme we
have a vital force which is now only a directing idea,
without objective existence, and without an executive
role; a mere concept by which the mind gathers
together and conceives of a succession of physico-
chemical phenomena. On this side we are brought
into touch with monism.

l8 LIFE AND DEATH.

The Reasons given by the Vitalists for distinguishing'
Soul from Life. — It is, in particular, on the opposite
side, in the psychical world, that the early vitalists pro-
fessed to entrench themselves. We have just seen that
their doctrines were not so subtle as those of to-day ;
the vital principle to them was a real agent, and not an
ideal plan in the process of being carried out. But
they distinguished this spiritual principle from another
co-existent with it in superior living beings — at any
rate, in man: the thinking soul. They boldly dis-
tinguished between them, because the activity of the
one is manifested by knowledge and volition, while
on the contrary, the manifestations of the other for
the most part escape both consciousness and volition.

In fact, we know nothing of what goes on in the
normal state of our organs. Their perfect performance
of their functions is translated to us solely by an
obscure feeling of comfort. We do not feel the beat-
ing of the heart, the periodic dilations of the arteries,
the movements of the lungs or intestine, the glands at
their work of secretion, or the thousand reflex mani-
festations of our nervous system. The soul, which is
conscious of itself, is nevertheless ignorant of all this
vital movement, and is therefore external to it.

This is the view of all the philosophers of antiquity.
Pythagoras distinguished the real soul, the thinking
soul, the Nous, the intelligent and immortal principle,
characterized by the attributes of consciousness and
volition, from the vital principle, the Psyche, which
gives breath and animation to the body, and which is
a soul of secondary majesty, active, transient, and
mortal. Aristotle did the same. On the one side he
placed the soul properly so called, the Nous or
intellect — that is to say, the understanding with its

VITALISM. 19

rational intelligence ; on the other side was the
directing principle of life, the irrational and vegeta-
tive Psyche.

This distinction agrees with the fact of the diffusion
of life. Life does not belong to the superior animals
alone, and to the man in whom we can recognize a
reasoning soul. It is extended to the vast multitude
of humbler beings to which such lofty faculties cannot
be attributed, the invertebrates, microscopic animals,
and plants. The advantage is compensated for by
the inconvenience of breaking down all continuity
between the soul and life; a continuity which is the
principle of the two other doctrines, animism and
monism, and which is, we may say, the very aim and
the unquestionable tendency of science.

As for classical philosophy, it satisfies the necessity
of establishing the unity of the living being, — i.e., of
bringing into harmony soul and body, — but in a
manner which we need not here discuss. It at-
tributes to the soul several modalities, several distinct
powers: powers of the vegetative life, powers of the
sensitive life, and powers of the intellectual life. And
this other solution of the problem would be, in the
opinion of M. Gardair, in complete agreement with
the doctrines of St. Thomas Aquinas.

§ I. The Vitalism of Barthez : its Extension.

Vitalism reached its most perfect expression in the
second half of the eighteenth century in the hands of
the representatives of the Montpellier school — Bordeu,
Grimaud, and Barthez. The last, in particular,
contributed to the prevalence of the doctrine in

20 LIFE AND DEATH.

medical circles. A man of profound erudition, a
collaborateur with d'Alembert in the Encyclopedia,
he exercisecJ quite a preponderant influence on the
medicine of his day. Stationed at Paris during part
of his career, physician to the King and the Duke of
Orleans, we may say that he supported his theories by
every imaginable influence which might contribute to
their success. In consequence of this, the medical
schools taught that vital phenomena are the immediate
effects of a force which has no analogues outside the
living body. This conception reigned unchallenged
up to the days of Bichat.

After Bichat, the vitalism of Barthez, more or less
modified by the ideas of the celebrated anatomist,
continued to hold its own in all the schools of
Europe until about the middle of the nineteenth
century. Johannes Miiller, the founder of physiology
in Germany, admitted, about 1833, the existence of a
unique vital force "aware of all the secrets of the
forces of physics and chemistry, but continually in
conflict with them, as the supreme cause and regulator
of all phenomena." When death came, this principle
disappeared and left no trace behind. One of the
founders of biological chemistry, Justus Liebig, who
died in 1873, shared these ideas. The celebrated
botanist, Candolle, who lived up to 1893, taught at
the beginning of his career that the vital force was one
of the four forces ruling in nature, the other three
being — attraction, affinity, and intellectual force.
Flourens, in France, made the vital principle one of
the five properties of forces residing in the nervous
system. Another contemporary, Dressel, in 1883,
endeavoured to bring back into fashion this rather
primitive, monistic, and efficient vitalism.

VITALISM. 21

The Seat of the Vital Principle. — Meanwhile,
another question was asked with reference to this
vital principle. It was a question of ascertaining its
seat: or, in other words, of finding its place in the
organism. Is it spread throughout the organism, or is
it situated in some particular spot from which it acts
upon every part of the body? Van Helmont, a cele-
brated scientist at the end of the sixteenth century,
who was both physician and alchemist, gave the first
and rather quaint solution of this difficulty. The vital
principle, according to him, was situated in the
stomach, or rather in the opening of the pylorus. It
was the concierge, so to speak, of the stomach. The
Hebrew idea was more reasonable. The life was
connected with the blood, and was circulated with it
by means of all the veins of the organism. It escaped
from a wound at the same time as the liquid blood.
It is clear that in this belief we see why the Jews were
forbidden to eat meat which had not been bled.

TJie Vital Kfiot. — In 1748 a doctor named Lorry
found that a very small wound in a certain region of
the spinal marrow brought on sudden death. The
position of this remarkable point was ascertained in
18 1 2 by Legallois, and more accurately still by
Flourens in 1827. It is situated in the i^chidian
bulb, at the level of the junction of the neck and the
head; or more precisely, on the floor of the fourth
ventricle, near the origin of the eighth pair of cranial
nerves. This is what was called the vital knot.
Upon the integrity of this spot, which is no bigger
than the head of a pin, depends the life of the animal.
Those who believed in a localisation of the vital
principle thought that they had found the seat
desired; but for that to be so the destruction of this

22 LIFE AND DEATH.

spot must be irremediable, and must necessarily cause
death. But if the vital knot be destroyed, and
respiration be artificially induced by means of a
bellows, the animal resists: it continues to live. It is
only the nervous stimulating mechanism of the
respiratory movements which has been attacked in
one of its essential parts.

Life, therefore, resides no more in this point than it
does in the blood or in the stomach. Later experi-
ment has shown that it resides everywhere, that each
organ enjoys an independent life. Each part of the
body is, to use Bordeu's strong expression, "a« animal
in an animal"; or to adopt the phrase due to Bichat,
^' a particular machine withiti the general machine."

The Vital Tripod. — What then is life, or, in other
words, what is the biological activity of the individual,
of the animal, of man ? It is clearly the sum total, or
rather, the harmony of these partial lives of the
different organs. But in this harmony it seems that
there are certain instruments which dominate and
sustain the others. There are some whose integrity
is more necessary to the preservation of existence and
health, and of which any lesion makes death more
inevitable. They are the lungs, the heart, and the
brain. Death always ensues, said the early doctors, if
any one of these three organs be injured. Life
depends, therefore, on them, as if upon a three-legged
support. Hence the idea of the vital tripod. It is no
longer a single seat for the vital principle, but a kind
of throne on three-supports. Life is decentralized.

This was only the first step, very soon followed by
many others, in the direction of vital decentralization.
Experiment showed, in fact, that every organ separated
from the body will continue to live if provide'd with

VITALISM. 23

the proper conditions. And here, it is not only a
question of inferior beings; of plants that are pro-
pagated by sh'ps ; of the hydra which Trembley cut
into pieces, each of which generated a complete hydra ;
of the na'is which C. Bonnet cut up into sections, each
of which reconstituted a complete annelid. There is
no exception to the rule.

Decentralization of the Vital Principle. — The result
is the same in the higher vertebrates, only the experi-
ment is much more difficult. At the Physiological
Congress of Turin in 1901, Locke showed the heart of
a hare, extracted from the body of the animal, and
beating for hours as energetically and as regularly as
if it were in its place. He suspended it in the air of
a room at the normal temperature, the sole condition
being that it was irrigated with a liquid composed of
certain constituents. The animal had been dead some
time. More recently Kuliabko has shown in the same
way the heart of a man still beating, although the
man had been dead some eighteen hours. The same
experiment is repeated in any physiological labora-
tory, in a much easier manner, with the heart of a
tortoise. This organ, extracted from the body, fitted
up with rubber tubes to represent its arteries and
veins, and filled with the defibrinated blood of a horse
or an ox taken from the slaughter-house, works for
hours and days pumping the liquid blood into its
rubber aorta, just as if it were pumping it into the
living aorta.

But it is unnecessary to multiply examples. Every
organ can be made to live for a longer or shorter
period even though removed from its natural position;
muscles, nerves, glands, and even the brain itself.
Each organ, each tissue therefore enjoys an inde-

3

24 LIFE AND DEATH.

pendent existence; it lives and works for itself.
No doubt it shares in the activity of the whole, but
it may be separated therefrom without being thereby
placed in the category of dead substances. For each
aliquot part of the organism there is a partial life and
a partial death.

This decentralization of the vital activity is finally
extended in complex beings from the organs to the
tissues, and from the tissues to the anatomical
elements — the cells. The idea of decentralization
has given birth to the second form of vitalism, a
softened down and weakened form — namely, pluri-
vitalism, or the theory of vital properties.

§ 2. The Theory of Vital Properties.

The advocates of the theory of vital properties have
cut up into fragments the monistic and indivisible
guiding principle of Bordeu and Barthez. They have
given it new currency — pluri-vitalism. This theory
maintains the existence of spiritual powers of a lowibr
order, which control phenomena more intimately than
the vital principle did. These powers, less lofty in
their dignity than the rational soul of the animists, or
the soul of secondary majesty of the unitarian
vitalists, are eventually incorporated in the living
matter of which they will then be no longer more
than the properties. Brought into closer connection
therefore with the sensible world, they will be more
in harmony with the spirit of research and with
scientific progress.

The defect of the earlier conceptions, their common
illusion, rose from their seeking the cause outside the

VITALISM. 25

object, from their demanding an explanation of vital
phenomena from a principle external to living,
immaterial, and unsubstantial matter. Here this
defect is less marked. The pluri-vitalists will in turn
appeal to the vital properties as modes of activity,
inherent in the living substance in which and by which
they are manifested, and derived from the arrangement
of the molecules of this substance — that is to say, from
its organization. This is almost the conception of
the present day.

But this progress will only be realized at the end of
the evolution of the pluri-vitalist theory. At the outset
this theory seems an exaggeration of its predecessor,
and a still more exaggerated form of the mythological
paganism with which it was reproached. The archeus,
the bias, the properties, the spirits — all have at first
the effect of the genii or of the gods imagined by the
ancients to preside over natural phenomena, of
Neptune stirring up the waters of the sea, and of
Eolus unchaining the winds. These divinities of the
anipient world, the nymphs, the dryads, and the sylvan
gods, seem to be transported to the Middle Ages, to
that age of argument, that philosophical period of the
history of humanity, and there metamorphosed into
occult causes, immaterial powers, and personified
forces.

Galen. — The first of the pluri-vitalists was Galen,
the physician of Marcus Aurelius, the celebrated
author of an Encyclopaedia of which the greater part
has been lost, and of which the one book preserved
held its own as the anatomical oracle and breviary
throughout the Middle Ages, According to Galen
the human machine is guided by three kinds of
spirits: animal spirits, presiding over the activity of

26 LIFE AND DEATH.

the nervous system; vital spirits governing most of
the other functions; and finally, natural spirits
regulating the liver and susceptible of incorporation
in the blood. In the sixteenth century, in the time of
Paracelsus, Galen's spirits became Olympic spirits.
They still presided over the functional activity of the
organs, the liver, heart, and brain, but they also
existed in all the bodies of nature.

Van Helmont. — Finally, the theory was laid down
by Van Helmont, physician, chemist, experimentalist,
and philosopher, endowed with a rare and penetrating
intellect. Here we find many profound truths com-
bined with fantastic dreams. Refusing to admit the
direct action of an immaterial agent, such as the soul,
on inert matter, on the body, he filled up the abyss
which separated them by creating a whole hierarchy
of immaterial principles which played the part of
mediators and executive agents. At the head of this
hierarchy was placed the thinking and immortal soul ;
below was the sensitive and mortal soul, having for its
minister the principal archeus, the aura vitalis, a kind
of incorporeal agent, which is remarkably like the
vital principle, and which had its seat at the orifice of
the stomach. Below again were the subordinate
agents, the bias, or vulcans placed in each organ, and
intelligently directing its mechanism like skilful
workmen.

These chimerical ideas are not, however, so far
astray as the theory of vital properties. When we
see a muscle contract, we say that this phenomenon
is due to a vital property — i.e., a property without any
analogue in the physical world, namely contractility.
In the same way the nerve possesses two vital
properties, excitability and conductibility,\Nh\c\\ Vulpian

VITALISM. 27

proposed to blend into one, calling it neurility. These
are mere names, serving as a kind of shorthand ; but
to those who believe that there is something real in it,
this something is not very far from the bias of Van
Helmont. Vukatis, hidden in the muscle or the nerve,
are here detected by attraction, there by the pro-
duction and the propagation of the nervous influx;
that is to say, by phenomena of which we as yet
know no analogues in the physical world, but of
which we cannot say that they do not exist.

X. Bichat and G. Cuvier: Vital and Physical
Properties Antagonistic. — The archeus and the bias of
Van Helmont were but a first rough outline of
vital properties. Xavier Bichat, the founder of general
anatomy, wearied of all these incorporeal entities, of
these unsubstantial principles with which biology was
encumbered, undertook to get rid of them by the
methods of the physicist and the chemist. The physics
and the chemistry of his day referred phenomenal
manifestations to the properties of matter, gravity,
capillarity, magnetism, etc. Bich4t did the same.
He referred vital manifestations to\ the properties of
living tissues, if not, indeed, of living matter. Of
these properties as yet but very few were known :
the irritability described by Glisson, which is the
excitability of current physiology ; and the irritability
of Haller, which is nothing but muscular contrac-
tility. Others had to be discovered.

There is no need to recall the mistake made by
Bichat and followed by most scientific men of his
time, such as Cuvier in France, and J. Miiller in
Germany, for the story has been told by Claude
Bernard. His mistake was in considering the vital
properties not only as distinct from physical properties

28 LIFE AND DEATH.

but even as opposed to them. The one preserve the
body, the others tend to destroy it. They are always
in conflict. Life is the victory of the one; death is
the triumph of the other. Hence the celebrated
definition given by Bichat: "Life is the sum total of
functions which resist death," or the definition of the
Encyclopaedia: "Life is the contrary of death."

Cuvier has illustrated this conception by a graphic
picture. He represents a young woman in all the
health and strength of youth suddenly stricken by
death. The sculptural forms collapse and show the
angularities of the bones; the eyes so lately sparkling
become dull; the flesh tint gives place to a livid
pallor; the graceful suppleness of the body is now
rigidity, "and it will not be long before more horrible
changes ensue ; the flesh becomes blue, green, black,
one part flows away in putrid poison, and another
part evaporates in infectious emanations. Finally,
nothing is left but saline or earthy mineral principles,
all the rest has vanished." Now, according to Cuvier,
what has happened ?

These alterations are the effect of external agents,
air, humidity, and heat. They have acted on the
corpse just as they used to act on the living being;
but before death their assault had no effect, because it
was repelled by the vital properties. Now that life
has disappeared the assault is successful. We know
now that external agents are not the cause of these
disorders. They are caused by the microbes of
putrefaction. It is against tJieni that the organs were
struggling, and not against physical forces.

The mistake made by Bichat and Cuvier was in-
excusable, even in their day. They were wrong not
to attach the importance they deserved to Lavoisier's

VITALISM. 29

researches. He had asserted, apropos of animal heat
and respiration, the identity of the action of physical
agents in the living body and in the external world.
On the other hand, Bichat, by a flash of genius, de-
centralized life, dispersing the vital properties in the
tissues, or, as we should now say, in the living matter.
It was from the comparison between the constitution
and the properties of living matter and those of in-
animate matter that light was to come.

§ 3. Scientific Neo-Vitalism.

We can now understand the nature of modern
neo-vitalism. It borrows from its predecessor its
fundamental principle — namely, the specificity of the
vital fact. But this specificity is no longer essential,
it is or\\y formal. The difference between it and the
physical fact grows less and almost vanishes. It con-
sists of a diversity of mechanisms or executive agents.
For example, digestion transforms the alimentary
starch in the intestines into sugar; the chemist does
the same in his laboratory, only he employs acids,
while the organism employs special agents, ferments,
in this case a diastase. It is a particular form of
chemistry, but still it is a chemistry. That is how
Claude Bernard looked at it. The vital fact was not
fundamentally distinguished from the physico-chemi-
cal fact, but only in form.

This expurgated and accommodated vitalism
(Claude Bernard pushed his concessions so far as to
call his doctrine " physico-chemical vitalism ") was re-
vived a few years ago by Chr. Bohr and Heidenhain.

Other biologists, instead of attributing the difference

32 LIFE AND DEATH.

physiological factors. It would therefore seem that
the vital force, to use a rather questionable form
of language, withdraws in a certain measure the
organized being from the realm of physical forces —
and this conclusion is one form of contemporary
neo-vitalism.

§ 4. Philosophical Neo-Vitalism.

Contemporary neo-vitalism has assumed another
form, more philosophical than scientific, by which it is
brought closer to vitalism, properly so called. We
should like to mention the experiment of Reinke,^
in Germany. Reinke is a botanist of distinction, who
distinguishes the speculative from the positive domain
of science, and cultivates both with success.

His ideas are analogous to those of A. Gautier, of
Chevreul, and of Claude Bernard himself He thinks,
with these masters, that the mystery of life is not to be
found in the nature of the forces that it brings into
play, but in the direction that it gives them. All these
thinkers are struck by the order and the direction
impressed upon the phenomena which take place
in the living being, by their interconnection, by their
apparent adaptation to an end, by the kind of im-
pression that they give of a plan which is being
carried out. All these reflections lead Reinke to
attach great weight to the idea of a " directing
force."

The physico-chemical energies are no doubt the
only ones which are manifested in the organized
being, but they are directed as a blind man is by his

* Reinke, Die Welt als Thai; Berlin, 1899.

VITALISM. 33

guide. It seems as if a double accompanies them like
a shadow. This intelligent guide of blind, material
force is what Reinke calls a dominant. Nothing
could be more like the bias and the archeus of Van
Helmont. Material energies would thus be paired
off with their bias, their dominants, in the living
organisms. In them there would therefore be two cate-
gories of force : " material forces," or rather, material
energies obeying the laws of universal energetics;
and in the second place, intelligent " spiritual forces,"
the dominants. When the sculptor is working his
marble, in every blow which elicits a spark there is
something more than the strong force of the hammer.
There is thought, the volition of the artist, which is
realizing a plan. In a machine there is more than
machinery. Behind the wheels is the object which
the author had in view when he adjusted them for a
determined end. The energies spent in action are
regulated by the adjustment — that is to say, by the
dominants due to the intellect of the constructor.

Thus it is in the living machine. The dominants
in this case are the guardians of the plan, the agents
of the aim in view. Some regulate the functional
activity of the living body, and some regulate its
development and its construction. Such is the second
form, the philosophical form, extreme and teleological,
of contemporary neo-vitalism.

32 LIFE AND DEATH.

physiological factors. It would therefore seem that
the vital force, to use a rather questionable form
of language, withdraws in a certain measure the
organized being from the realm of physical forces —
and this conclusion is one form of contemporary
neo-vitalism.

§ 4. Philosophical Neo- Vitalism.

Contemporary neo-vitalism has assumed another
form, more philosophical than scientific, by which it is
brought closer to vitalism, properly so called. We
should like to mention the experiment of Reinke,^
in Germany. Reinke is a botanist of distinction, who
distinguishes the speculative from the positive domain
of science, and cultivates both with success.

His ideas are analogous to those of A. Gautier, of
Chevreul, and of Claude Bernard himself He thinks,
with these masters, that the mystery of life is not to be
found in the nature of the forces that it brings into
play, but in the direction that it gives them. All these
thinkers are struck by the order and the direction
impressed upon the phenomena which take place
in the living being, by their interconnection, by their
apparent adaptation to an end, by the kind of im-
pression that they give of a plan which is being
carried out. All these reflections lead Reinke to
attach great weight to the idea of a " directing
force."

The physico-chemical energies are no doubt the
only ones which are manifested in the organized
being, but they are directed as a blind man is by his

^ Re'mke, Die Well als That; Berlin, 1899.

VITALISM. 33

guide. It seems as -if a double accompanies them like
a shadow. This intelligent guide of blind, material
force is what Reinke calls a dominant. Nothing
could be more like the bias and the archeus of Van
Helmont. Material energies would thus be paired
off with their bias, their dominants, in the living
organisms. In them there would therefore be two cate-
gories of force : " material forces," or rather, material
energies obeying the laws of universal energetics;
and in the second place, intelligent "spiritual forces,"
the dominants. When the sculptor is working his
marble, in every blow which elicits a spark there is
something more than the strong force of the hammer.
There is thought, the volition of the artist, which is
realizing a plan. In a machine there is more than
machinery. Behind the wheels is the object which
the author had in view when he adjusted them for a
determined end. The energies spent in action are
regulated by the adjustment — that is to say, by the
dominants due to the intellect of the constructor.

Thus it is in the living machine. The dominants
in this case are the guardians of the plan, the agents
of the aim in view. Some regulate the functional
activity of the living body, and some regulate its
development and its construction. Such is the second
form, the philosophical form, extreme and teleological,
of contemporary neo-vitalism.

CHAPTER IV.

THE MONISTIC THEORY.

Physico-chemical Theory of Life. — latro-mechanism. — Des-
cartes, Borelli. — latro-chemistry. — Sylvius le Boe. — The
Physico-chemical Theory of Life. — Matter and Energy. —
Heterogeneity is merely the result of the arrangement or
combination of homogeneous bodies. — Reservation relative
to the world of thought. — The Kinetic Theory.

The unicist or monistic doctrine gives us a third way
of conceiving the functional activity of the living
being, by levelling and blending its three forms of
activity — spiritual, vital, and material. It was
expressed in the seventeenth and eighteenth centuries
in "iatro-mechanism " and " iatro-chemistry," concep-
tions to which have more recently succeeded the
physico-chemical doctrine of life, and finally "current
materialism,"

Materialism is not only a biological interpretation ;
it is a universal interpretation applicable to the whole
of nature, because it is based on a determinate con-
ception of matter. Here we find ourselves confronted
by the eternal enigma discussed by philosophers
relative to this fundamental problem of force and
matter. We know what answers were given to
the problem by the Ionic philosophers — Thales,
Democritus, Heraclitus, and Anaxagoras, who dis-
carded the agency of every spiritual power external

34

THE MONISTIC THEORY. 35

to matter. The explanation of the world, the
explanation of life, were reduced to the play of
physical or mechanical forces. Epicurus, a little later,
maintained that the knowledge of matter and its
different forms accounts for all phenomena, and there-
fore for those of life.

Descartes, sharply separating the metaphysical
world — that is to say, the soul defined by its at-
tribute, thought — from the physical or material world
characterized by extension, practically came to the
same conclusions as the materialists of antiquity. To
him, as to them, the living body was a mere machine.

latro-mechanism. Descartes. Borelli. — This, then, is
the theory of the iatro-mechanicians, of which we may
consider Descartes the founder, instead of the Greek
philosophers. These ideas held their own for two
centuries, and were productive of such fruitful results
in the hands of Borelli, Pitcairn, Hales, Bernoulli, and
Boerhaave, as to justify the jest of Bacon that "the
philosophy of Epicurus had done less harm to science
than that of Plato." The iatro-mechanic school ten-
aciously held its own until Bichat came upon the scene.

latro-cJiemistry. Sylvius le Bo'e. — It was from a
reaction against their exaggerations that Stahl
created animism, and the Montpellier school created
vitalism. We gather some idea of the extravagant
character of their explanations by reading Boerhaave.
To this celebrated doctor the muscles were springs,
the heart was a pump, the kidneys a sieve, and the
secretions of the glandular juices were produced by
pressure ; the heat of the body was the result of the
friction of the globules of blood against the walls of
the blood-vessels; it was greater in the lungs because
the vessels of the lungs were supposed to be narrower

36 LIFE AND DEATH.

than those of other organs. The inadequacy of these
explanations suggested the idea of completing them
by the aid of the chemistrj'' which was then springing
into being. This chemistry, rudimentary as it was,
longed for a share in the government of living bodies
and in the explanation of their phenomena. Dis-
tillations, fermentations, and effervescences are now
seen to play their role, a role which was premature
and carried to excess. latro-chemistry from the
general point of view is only an aspect of iatro-
mechanics ; but it is also an auxiliary. Sylvius le Boe
and Willis were its most eminent representatives.
This theory remained in the background until
chemistry made its great advance — that is to say, in
the days of Lavoisier. After that, its importance has
gradually increased, particularly in the present day.
Nowadays, the general tendency is to regard the
organic functional activity, or even morphogeny — />.,
whatever there is that is most peculiar to and char-
acteristic of living beings — as a consequence of the
chemical composition of their substance. This is a
point of capital importance, and to it we must recur.

The Physico-chemical Theory of Life. — Contemporary
biological schools have made many efforts to secure
themselves from any slips on the philosophical side.
They have avoided in most cases the psychological
problem; they have deliberately refrained from
penetrating into the world of the soul. Hence, the
pliysico-cheinical theory of life has been built up free
from spiritualistic difficulties and objections. But
this prudence did not exclude the tendency. And
there is no doubt, as Armand Gautier said, that "real
science can affirm nothing, but it also can deny
nothing outside observable facts ; " and again, that

THE MONISTIC THEORY. 37

"only a science progressing backwards can venture to
assert that matter alone exists, and that its laws alone
govern the world." It is none the less true that by
establishing the continuity between inert matter and
living matter, we thereby render probable the con-
tinuity between the world of life and the world of
thought.

Matter and Energy. — Besides, and without any
wish to enter into this burning controversy, it is
only too evident that there is no agreement as to the
terms that are used, and in particular as to " matter "
and "laws of matter." It is not necessary to repeat
that the geometrical mould in which Descartes cast
his philosophy has long since been broken. The
celebrated philosopher, in defining matter by one
attribute — extension, does not enable us to grasp its
activity, an activity revealed by all natural facts ; and
in defining the soul by thought alone, prevents us
from seeking in it the principle of this material activity.
This purely passive matter, consisting of extension
alone, this bare matter was to Leibniz a pure concept.
A philosopher of our own time, M. Magy, has called it
a sensorial illusion. The bodies of nature exhibit to
us matter clad with energy, formed by the indissoluble
union of extension with an inseparable dynamical
principle. The Stoics declared that matter is mobile
and not immobile, active and not inert Leibniz also
had this in his mind when he associated it indissolubly
with an active principle, an "entelechy." Others have
said that matter is " an assemblage of forces," or with
P. Boscovitch, " a system of indivisible points without
extension, centres of force, in fact." Space would be
the geometrical locus of these points.

In this conception the materialistic school finds the

38 LIFE AND DEATH. *

explanation of all phenomenality. Physical properties,
vital phenomena, psychital facts, all have their founda-
tion in this immanent activity. Material activity is
a minimum of soul or thought which, by continuous
gradation and progressive complexity, without solution
of continuity, without an abrupt transition from the
homogeneous to the heterogeneous, rises through the
series of living beings to the dignity of the human
soul. The observation ot the transitions, an imperfect
tracing of the geometrical method of limits, thus
enables us to pass from material to vital, and from
thence to psychical activity.

Apparent Helerogeneity is the Result ojtJie Arrange-
ment or the Combination of Homogeneous Bodies. — In
this system, material energy, life, soul would only be
more and more complex combinations of the con-
substantial activity with material atoms. Life appears
distinct from physical force, and thought from life,
because the analysis has not yet advanced far enough.
Thus, glass would appear to the ancient Chaldeans
distinct from the sand and salt of which they made it.
In the same way, again, water, to modern eyes, is
distinct from its constituents, oxygen and hydrogen.
The whole difficulty is that of explaining what this
"arrangement" of the elements can introduce that
is new in the aspect of the compound. We must
know what novelty and apparent homogeneity the
variety of the combinations, w^hich are only special
arrangements of the elementary parts, may produce in
the phenomena. But we do not know, and it is this
ignorance which leads us to consider them as hetero-
geneous, irreducible, and distinct in principle. The
vital phenomenon, the complexus of physico-chemical
facts, thus appears to us essentially different from

THE MONISTIC THEORY. 39

those facts, and that is why we picture to ourselves
"dominants" and "directing forces" more or less
analogous to the sidereal guiding principle of Kepler,
which, before the discovery of universal attraction,
regulated the harmony of the movements of the
planets.

A Reservation relative to the Psychical Order. —
The scientific mind has shown in every age a real
predilection towards the mechanical or materialistic
theory. Contemporary scientists as a whole have
accepted it in so far as it blends the vital and the
physical orders. Objections and contradictions are
only offered in the realm of psychology. A. Gautier,
for example, has contested with infinite originality
and vigour the claims of the materialists who would
reduce the phenomenon of thought to a material
phenomenon. The most general characteristic of
material phenomenality is — as we shall later see —
that it may be considered as a mutation of energy —
i.e., it obeys the laws of energetics. Now thought,
says A. Gautier, is not a form of material energy.
Thought, comparison, volition, are not acts of material
phenomenality; they are states. They are realities;
they have no mass; they have no physical existence.
They respond to adjustments, arrangements, and
concerted groupings of material manifestations of
chemical molecules. They escape the laws of
energetics.

Kinetic Theory. — We shall lay aside for a moment
this serious problem relative to the limits of the world
of conscious thought and of the world of life. It is on
the other side, on the frontiers of living and inani-
mate nature, that the mechanical view triumphs. It
has furnished a universal conception agreeing with

4

40 LIFE AND DEATH.

phenomena of every kind — viz., the kinetic theory,
which ascribes everything in nature to the movements
of particles, molecules, or atoms.

The living and the physical orders are here reduced
to one unique order, because all the phenomena of the
sensible universe are themselves reduced to one and
the same mechanics, and are represented by means o(
the atom and of motion. This conception of the
world, which was that of the philosophers of the Ionic
school in the remotest antiquity, which was modified
later by Descartes and Leibniz, has passed into
modern science under the name of the kinetic theory.
The mechanics of atoms ponderable or imponderable,
would contain the explanation of all phenomenality.
If it were a question of physical properties or vital
manifestations, the objective world in final analysis
would offer us nothing but motion. Every pheno-
menon would be expressed by an atomistic integral,
and that is the inner reason of the majestic unity
which reigns in modern physics. The forces which
are brought into play by Life are no longer to
be distinguished in this ultimate analysis from
other natural forces. All are blended in molecular
mechanics.

The philosophical value of this theory is undeniable.
It has exercised on physical science an influence which
is justified by the discoveries which it has suggested.
But to biology, on the other hand, it has lent no aid.
It is precisely because it descends too deeply into
things, and analyzes them to the uttermost, that it
ceases to throw any light upon them. The distance
between the hypothetical atom and the apparent and
concrete fact is too great for the one to be able to
throw light on the other The vital phenomenon

The monistic theory. 4I

vanishes with its individual aspect; its features can
no longer be distinguished.

Besides, a whole school of contemporary physicists
(Ostwald of Leipzig, Mach of Vienna) is beginning to
cast some doubt on the utility of the kinetic hypothesis
in the future of physics itself, and is inclined to pro-
pose to substitute for it the theory of energetics. We
shall see, in every case, that this other conception, as
universal as the kinetic theory, tJie theory of Energy,
causes a vivid light to penetrate into the depths of the
most difficult problems in physiology.

Such are, with their successive transformations, the
three principal theories, the three great currents
between which biology has been tossed to and fro.
They are sufficiently indicative of the state of positive
science in each age, but one is astonished that they
are not more so; and this is due to the fact that these
conceptions are too general. They soar too high above
reality. More characteristic in this respect will be
particular theories of the principal manifestations of
living matter, of its perpetuity by generation, of the
development by which it acquires its individual form,
on heredity. It is here that it is of importance to
grasp the progressive march of science — that is to say,
the design and the plan of the building which is being
erected, " blindly, so to speak," by the efforts of an
army of workers, an army becoming more numerous
day by day.

CHAPTER V.

THE EMANCIPATION OF SCIENTIFIC RESEARCH
FROM THE YOKE OF PHILOSOPHICAL THEORIES.

The excessive use of Hypothetical Agents in Physiological
Explanations — § I. Vital Phenomena in Fully-constituted
Organisms — Provisory Exclusion of the Morphogenic
idea — The Realm of the Morphogenic Idea as the
Sanctuary of Vital Forced 2. The Physiological Domain
properly so called — Harmony and Connection of Pheno-
mena— Directive Forces — Claude Bernard's Work —
Exclusion of Vital Force, of Final Cause, of the " Caprice "
of Living Nature — Determinism — The Comparative
Method — Generality of Vital Phenomena — Views of
Pasteur.

The theories whose history we have just sketched
in broad outh'ne long dominated science and exer-
cised their influence on its progress.

This domination has ceased to exist. Physiology
has emancipated itself from their sway, and this,
perhaps, is the most important revolution in the whole
history of biology. Animism, vitalism, materialism,
have ceased to exercise their tyranny on scientific
research. These conceptions have passed from the
laboratory to the study; from being physiological,
they have become philosophical.

This result is the work of the physiologists of sixty
years ago. It is also the consequence of the general
march of science and of the progress of the scientific
spirit, which shows a more and more marked tendency

42

EMANCIPATION OF SCIENTIFIC RESEARCH. 43

to separate completely the domain of facts from the
domain of hypotheses.

Excessive Use of Hypothetical Agents in Physio-
logical Explanations. — It may be said that in the
early part of the nineteenth century, in spite of the
efforts of a few real experimenters from Harvey to
Spallanzani, Hales, Laplace, Lavoisier, and Magendie,
the science of the phenomena of life had not followed
the progress of the other natural sciences. It remained
in the fog of scholasticism. Hypotheses were mingled
with facts, and imaginary agents carried out real acts,
in inexpressible confusion. The soul (animism), the
vital force (vitalism), and the final cause (finalism,
teleology) served to explain everything.

In truth, it was also at this time that physical
agents, electric and magnetic fluids, or, again, chemical
affinity, played an analogous part in the science of
inanimate nature. But there was at least this
difference in favour of physicists and chemists, that
when they had attributed some new property or
aptitude to their hypothetical agents they respected
what they attributed. The physiological physicians
respected no law, they were subject to no restraint.
Their vital force was capricious; its spontaneity made
anticipation impossible; it acted arbitrarily in the
healthy body; it acted more arbitrarily still in the
diseased body. All the subtlety of medical genius
was called into play to divine the fantastic behaviour
of the spirit of disease. If we speak here of physio-'
logists and doctors alone and do not quote biologists,
it is because the latter had not yet made their
appearance as authorities ; their science had remained
purely descriptive, and they had not yet begun to
explain phenomena.

44 LIFE AND DEATH.

Such was the state of things during the first years
of the nineteenth century. It lasted, thanks to the
founders of contemporary physiology — Claude Bernard
in France, and Brlicke, Dubois-Reymond, Helmholtz,
and Ludvvig in Germany — until a separation took
place between biological research and philosophical
theories. This delimitation operated in physiology
properly so called — i.e. in a branch of the biological
domain in which as yet joint tenancy had been the
rule. An important revolution fixed the respective
divisions of experimental science and philosophical
interpretation. It was understood that the one ends
where the other begins, that the one follows the other,
that one may not cross the other's path. There is
between them only one doubtful region about which
there is dispute, and this uncertain frontier is con-
stantly being shifted and science daily gains what
philosophy loses.

§ I. Vital Phenomena in Constituted
Organisms.

A displacement of this kind had taken place at the
time of which we speak. It was agreed, that as far as
concerns the phenomena which take place in a con-
structed and constituted living organism, it would no
longer be permissible to allow to intervene in their
explanation forces or energies other than those
which are brought into play in inanimate nature.
Just as when explaining the working of a clock,
the physicist will not invoke the volition or the art
of the maker, or the design that he had in view, but
only the connection of causes and effects which he
has utilized ; so, for the living machine, whether the

EMANCIPATION OF SCIENTIFIC RESEARCH. 45

most complex, such as the human body, or the most
elementary, such as the cell, we may not invoke a
final cause, a vital force, external to that organism
and acting on it from without, but only the con-
nections and the fluctuations of effects which are the
sole actual and efficient causes. In other words
Ludwig, and Claude Bernard in particular, expelled
from the domain of active phenomenality the three
chimeras — Vital Force, Final Cause, and the "Caprice"
of Living Nature.

But the living being is not only a completely con-
structed and completely constituted organism. It is not
a finished clock. It is a clock which is making itself,
a mechanism which is constructing and perpetuating
itself. Nothing of the kind is known to us in inani-
mate nature. Physiology has found — in what is
called morphogeny — its temporary limit. It is beyond
this limit, it is in the study of phenomena by which
the organism is constructed and perpetuated, it is in
the region of the functions of generation and develop-
ment, that philosophical doctrines expand and flourish.
This is the present frontier of these two powers,
philosophy and science. Wc shall presently delimit
them more precisely. W. Kiihne, a well-known
scientist whose death is deplored, not in Germany
alone, amused himself by studying the division of
biological doctrines among the members of learned
societies and in the world of academies. He
summed up this kind of statistical inquiry by
saying in 1898 at the Cambridge Congress, that
physiologists were nearly all advocates of the physico-
chemical doctrine of life, and that the majority of
naturalists were advocates of vital force, and of the
theory of final causes,

46 LIFE AND DEATH.

Domain of the Morphogenic Idea as the Last Sanc-
tuary of Vital Force. — We see the reason for this.
Physiology, in fact, has taken up its position in
the explanation of the functional activity of the
constituted organism — i.e., on a ground where
intervene, as we shall show further on, no energies
and no matter other than universal energies and
matter. Naturalists, on the other hand, have more
especially considered — and from the descriptive point
of view alone, at least up to the times of Lamarck
and Darwin — the functions, the generation, the
development and the evolution of species. Now
these functions are most refractory and inaccessible
to physico-chemical explanations. So, when the
time came to give an account of what they had done,
the zoologists had substituted for executive agents
nothing but vital force under its different names.
To Aristotle it is the vital force itself which, as soon
as it is introduced into the body of the child, moulds
its flesh and fashions it in the human form. Con-
temporary naturalists, the Americans C. O. Whitman
and C. Philpotts, for example, take the same line of
argument. Others, such as Blumenbach and Needham,
in the eighteenth century, invoked the same division
under another name, that of the nistis formativns.
Finally, others play with words ; they talk of heredity,
of adaptation, of atavism, as if these were real, active,
and efficient beings; while they are only appella-
tions, names applied to collections of facts.

This region was therefore eminently favourable
to the rapid increase of hypotheses, and so they
abounded. There were the theories of Buffon, of
Lamarck, of Darwin, of Herbert Spencer, of E.
Haeckel, of His, of Weismann, of De Vrics, and

EMANCIPATION OF SCIENTIFIC RESEARCH. 47

of W. Roux. Each biologist of any mark liad his own,
and the list is endless. But here already this domain
of theoretical speculation is checked on various sides
by experiment. J. Loeb, a pure physiologist, has
recently given his researches a direction in which
zoology believes may be found the explanation of the
mysterious part played by the male element in
fecundation. On the other hand, the first experi-
ment of the artificial division of the living cell
(merotomy), with its light upon the part played by
the nucleus in the preservation and regeneration of
the living form, is also the work of a physiological
experimenter. It dates back to 1852, and is due to
Augustus Waller. This experiment was made on the
sensitive nervous cell of the spinal ganglions and on
the motor cell of the anterior cornua of the spinal
cord. The effects were correctly interpreted twelve
or fifteen years later. All that zoologists have done
is to repeat, perhaps unconsciously, this celebrated
experiment and to confirm the result.

Thiis we see that the attack upon the vitalist
sanctuary has commenced. But it would be a grave
mistake to suppose that final cause and vital force are
on the point of being dislodged from their entrench-
ments. Philosophical speculation has an ample field
before it. Its frontiers may recede. For a long time
yet there will be room for a more or less modernized
vitalism.

§ 2. The Physiological Domain properly so

CALLED.

Vitalism is even found installed in the region of
physiology, although for the moment this science
limits its ambition to the consideration of the com-

48 LIFE AND DEATH.

pletely constructed organized being, perfected in its
form. The explanation of the working of this con-
stituted machine cannot be complete until we take
into account the harmony and the adjustment of its
parts.

Harmony and Connection of Parts: Directive Forces.
— These constituent parts are the cells. We know
that the progress of anatomy has resulted in the
cellular doctrine — i.e.y in the two-fold affirmation
that the most complicated organism is composed of
microscopic elements, the cells, all similar, true
stones of the living building, and that it derives its
origin from a single cell, ^^g, or spore, the sexual cell,
or cell of germination. The phenomena of life, looked
at from the point of view of the formed individual,
are therefore harmonized in space ; just as, regarded
from the point of view of the individual in formation
and in the species, they are connected in time. This
harmony and this connection are in the eyes of the
majority of men of science the most characteristic pro-
perties of the living being. This is the domain oi vital
specificity, of the directive forces of Claude Bernard and
A. Gautier, and of the dominants of Rcinkc. It is not
certain, however, that this order of facts is more
specific than the other. Generation and development
have been considered by many physiologists, and
quite recently by Le Dantec, as simple aspects or
modalities of nutrition or assimilation, the common
and fundamental property of every living cell.

The Work of Claude Bernard. Exclusion of Vital
Force, of Vital Cause, oj the " Caprice " of Living Nature.
— It is not, however, a slight advance or inconsider-
able advantage to have eliminated vitalistic hypotheses
from almost the whole domain of present-day physi-

EMANCIPATION OF SCIENTIFIC RESEARCH. 49

ology, and to have them, as it were, thrown back into
its hinterland. This is the work of the scientific men
of the first half of the nineteenth century, and parti-
cularly of Claude Bernard, who has thereby won
the name of the founder or lawgiver of physiology.
They found in the old medical school an obstinate
adversary glorying in its sterile traditions. In vain
was it proved that vital force cannot be an efficient
cause; that it was a creation of the brain, an insub-
stantial phantom introduced into the anatomical
marionette and moving it by strings at the will of
any one — its adepts having only to confer upon it a
new kind of activity to account for the new act. All
that had been shown with the utmost clearness by
Bonnet of Geneva, and by many others. It had also
been said that the teleological explanation is equally
futile, since it assigns to the present, which exists, an
inaccessible, and evidently ultimately inadequate cause,
which does not yet exist. These objections were in
vain.

Determinism. — And so it was not by theoretical
arguments that the celebrated physiologist dealt with
his adversaries, but by a kind of lesson on things. In
fact he was continually showing by examples that
vitalism and the theory of final causes were idle errors
which led astray experimental investigation ; that
they had prevented the progress of research and the
discovery of the truth in every case and on every
point in which they had been invoked. He laid down
the principle of biological determinisju, which, is nothing
but the negation of the "caprice" of living nature.
This postulate, so evident that there was no need to
enunciate it in the physical sciences, had to be shouted
from the housetops for the benefit of supporters of

■ 50 LIFE AND DEATH.

vital spontaneity. It is the statement that, under
determined circumstances materially identical, the
same vital phenomena will be identically reproduced.
Comparative Method. — Claude Bernard completed
this critical work by laying down the laws of experi-
ment on living beings. He commended as the rational
method of research the comparative method. This
should be, and is in fact, the daily instrument of all
those who work in physiology. It compels the
investigator in every research bearing on organized
beings to institute a series of tests, such that the
conditions which are unknown and impossible to
know may be regarded as identical from one test to
another ; and when we are certain that a single
condition is variable, it compels him to discover the
character of the condition we are dealing with, and
to learn to appreciate, and to measure its influence.
It is safe to say that the errors which are daily
committed in biological work have their cause in
some infraction of this golden rule. In physical
science the obligation to follow the comparative
method is much less felt. In most cases the witness
test^ is useless. In physiology the witness test is
indispensable.

^ In an article on the experimental method recently published
in the Didionnaire de Physiologie, M. Ch. Richet writes as
follows: — "We must therefore never cease to carry out com-
parative experiments. I do not hesitate to say that this
comparison is the basis of the experimental method." It is in
fact what was taught by Claude Bernard in maxim and by
example. It is no exaggeration to assert that nine-tenths of the
errors which take place in research work are imputable to some
breach of this method. When an investigator makes a mistake,
save in the case of material error, it is almost certainly due to the
fact that he has neglected to carry out one of the comparative

EMANCIPATION OF SCIENTIFIC RESEARCH. 51

Generality of Vital Phenomena. — If we add that
Claude Bernard opposed the narrow opinion, so dear
to early medicine, which limited the consideration of
vitality to man, and the contrary notion of the essential
generality of the phenomena of life from man to the
animal, and from the animal to the plant, we shall
have given very briefly an idea of the kind of revolu-
tion which was accomplished about the year 1864, the
date of the appearance of the celebrated l' Introduction
a la niedecine experiuientale.

The ideas we have just recalled seem to be as
evident as they are simple. These principles appear
so well founded that in a measure they form an in-
tegral part of contemporary mentality. What scientist
would nowadays deliberately venture to explain some
biological fact by the intervention of the evidently
inadequate vital force or final cause ? And who, to

tests required in the problem before him. The following is
an instance which happened since the above pages were
written : — Several years ago a chemist announced the exist-
ence in the blood serum of a ferment, lipase, capable of
saponifying fats— that is to say, of extracting from them the fatty
acid. From this he deduced many consequences relative to the
mechanism of fermentations. But on the other hand, it has
been since shown (April 1902) that this lipase of the serum
does not exist. How did the error arise ? The author in
question had mixed normally obtained serum with oil, and he
had noted the acidification of the mixture ; he assured himself
of the fact by adding carbonate of soda. He saw the alkalinity
of the mixture, serum + oil + carbonate of soda, diminish, and he
drew the conclusion that the acid came from the saponified oil.
He did not make the comparative test, serum + carbonate of
soda. If he had done so, he would have ascertained that it also
succeeded, and that therefore as the acid did not come from
the saponification of the oil, since there was none, its production
could not prove the existence of a lipase.

52 LIFE ANt) DEATH.

account for the apparent inconsistency of the result,
would bring forward the "caprice" of living nature?
And who again would openly dispute the utility of
the comparative method ?

What the physiologists of to-day, according to
Claude Bernard, would no longer do, their pre-
decessors would do, and not the least important of
them. Longet, for example, at a full meeting of the
Academic, apropos of recurrent sensibility, and Colin
(of Alfort), communicating his statistical results on
the temperature of two hearts, accepted more or
less explicitly the indetermination of vital facts. And
why confine our remarks to our predecessors? The
scientists of to-day are much the same. So here
again we see the reappearance of the phantom of
the final cause in so-called scientific explanations.
One fact is accounted for by the necessity of the
self-defence of the organism ; another by the necessity
to a warm-blooded animal of keeping its temperature
constant. Le Dantec has recently reproached zoo-
logists for giving as an explanation of fecundation
the advantage that an animal enjoys in having a
double line of ancestors. We might as well say, as
L. Errera has pointed out, that the inundations of the
Nile occur in order to bring fertility to Egypt.

We must not therefore depreciate the marvellous
work which has emancipated modern physiology from
the tutelage of early theories. The witnesses of this
revolution appreciated its importance. One of them
remarked as follows, on the appearance of l' Introduc-
tion a la Dicdecine experinientaie, which contained,
however, only a portion of the theory : — " Nothing
more luminous, more complete, or more profound, has
ever been written upon the true principles of an art so

EMANCIPATION OF SCIENTIFIC RESEARCH. 53

difficult as that of experiment. This book is scarcely
known because it is on a level to which few people
nowadays attain. The influence it will have on medical
science, on its progress, and on its very language,
will be enormous. I cannot now prove my assertion,
but the reading of this book will leave so strong an
impression that I cannot help thinking that a new
spirit will at once inspire these splendid researches."
This was said by Pasteur in 1866. That is what he
thought of the work of his senior and his rival, at the
moment when he himself was about to inspire those
" splendid researches " with the movement of reform,
the importance and the consequences of which have
no equivalent in the history of science. By their
discoveries and their teaching, by their examples and
their principles, Claude Bernard and Pasteur have
succeeded in emancipating a portion of the domain of
vital facts from the direct intervention of hypothetical
agents and first causes. They were compelled, however,
to leave to philosophical speculation, to directing
forces, to animism, to vitalism, an immense provisory
field, the field which corresponds to the functions of
generation and of development, to the life of the
species and to its variations. Here we find them
again in various disguises.

BOOK II.

THE DOCTRINE OF ENERGY AND THE LIVING
WORLD.

Summary: General Ideas of Life. — Elementary Life. — Chapter
I. Energy in General. — Chapter II. Energy in Biology. —
Chapter III. Alimentary Energetics.

GENERAL IDEAS OF LIFE. ELEMENTARY LIFE.

Life is the Sum-total of the Phenomena Common
to all Living- Beings. Elementary Life. — Living
beings differ more in form and configuration than
in their manner of being. They are distinguished
more by their anatomy than by their physiology.
There are, in fact, phenomena common to all, from
the highest to the lowest. Tliis is because there is
that similar or identical foundation, that quid commune
which has enabled us to apply to them the common
name of " living beings." Claude Bernard gave to
this sum-total of manifestations common to all (nutri-
tion, reproduction) the name of elementary life. To
him general physiology was the study of elementary
life; the two expressions were equivalent, and they
were equivalent to a longer formula which the
illustrious biologist has given as a title to one of
his most celebrated works — The Study of the
Phenomena Common to all Living Beings, Animals,

54

GENERAL IDEAS OF LIFE. 55

and Plants. From this point of view each being is
distinguished from another being as a given individual
and as a particular species; but all are in some way
alike and thus resemble one another: common life,
elementary life, the essential phenomena of life; it is
life itself}

The manifestations of life may therefore be regarded
from the point of view of what is most general among
them. As we go down the scale of anatomical organ-
ization, as we pass from apparatus (circulatory,
digestive, respiratory, nervous) to the organs which
compose them, from the organs to the tissues, and
finally from the tissues to the anatomical elements or
cells of which they are formed, we approach that
common, physiological dynamism which is elementary
life^ but we do not actually reach it. The cell, the
anatomical element, is still a complicated structure.
The elementary fact is further from us and lower
down. It is in the living matter, in the molecule of
this matter, and there we must seek it.

Galen gave in days gone by as the object of
researches on life, the knowledge of the use of the
different organs of the animal machine; "de usu
partium." Later, Bichat assigned to them as their
end the determination of the properties of tissues.
Modern anatomists and zoologists try to reach the
constituent element of these tissues — the cell. Their
dream is to construct a cellular physiology, ?ii physio-
logical cytology ; but we must go further than that.

^ Le Dantec has objected to this conception of phenomena
common to different hving beings. He insists that all
phenomena which take place in a given living being are
proper to him, and differ, however slightly, from those of
another individual. The objection is more specious than real,

5

56 LIFE AND DEATH.

General Physiology, Cellular Physiology, the
Energetics of Living Beings. — General physiology,
as was taught by Pfluger and his school, claims
to go deeper down than the apparatus, or the
organ, or even the cell. As in the case of
physics, general physiology endeavours to reach,
and really does in many cases reach, as far as
the molecule. It is not cellular, it is inoleadar.
Already, in fact, the efforts of modern science have
succeeded in penetrating into the most general pheno-
mena of the living being — those attributable to living
matter, or, to speak more clearly, those which result
from the play of the universal laws of matter at work
in this particular medium which is the organized
being.

Robert Mayer and Helmholtz have the honour of
having set physiology in the right road. They
founded the energetics of living beings — i.e., they
regarded the phenomena of life from the point of
view of energy, which is the factor of all the pheno-
mena of the universe.

CHAPTER I.

ENERGY IN GENERAL.

Origin of the Idea of Energy. - The Phenomena of Nature bring
into play only two Elements, Matter and Energy. — § i.
Matter. — § 2. Energy.— § 3. Mechanical Energy. — § 4.
Thermal Energy.— § 5. Chemical Energy. — § 6. The Trans-
formations of Energy. — § 7. The Principles of Energetics. —
The Principle of the Conservation of Energy. — § 8. Carnot's
Principle. — The Degradation of Energy.

Origin of the Idea of Energy. — A new term, namely
energy ^\vdA been for some years introduced into natural
science, and has ever since assumed a more and more
important place. It is owing to the English physicists,
and especially to the English electrical engineers, that
this expression has made its way into technology, an
expression which is part and parcel of both languages,
and which has the same meaning in both. The idea
it expresses is, in fact, of infinite value in industrial
applications, and that is why its use has gradually
spread and become generalized. But it is not merely
a practical idea. It is above all a theoretical idea of
capital importance to pure theory. It has become
the point of departure of a science, energetics, which,
although born but yesterday, already claims to
embrace, co-ordinate, and blend within itself all the
other sciences of physical and living nature, which the
imperfection of our knowledge alone had hitherto
kept distinct and apart.

57

58 LIFE AND DEATH.

On the threshold of this new science we find in-
scribed the principle of the conservation of energy^
which has been presented to us by some as Nature's
supreme law, and which we may say dominates
natural philosophy. Its discovery marked a new era
and accomplished a profound revolution in our con-
ception of the universe. It is due to a doctor, Robert
Mayer, who practised in a little town in Wurtemberg,
and who formulated the new principle in 1842, and
afterwards developed its consequences in a series of
publications between 1845 and 1851. They remained
almost unknown until Helmholtz, in his celebrated
memoir on the conservation of force, brought them to
light and gave them the importance they deserved.
From that time forward the name of the doctor of
Heilbronn, until then obscure, has taken its place
among the most honoured names in the history of
science.^

^ Mayer's claim to fame has been disputed. A Scotch physicist,
P. G. Tait, has investigated the history of the law of the con-
servation of energy, which is the history of the idea of energy.
The conception has taken time to penetrate the human mind,
but its experimental proof is of recent date. P. G. Tait finds an
almost complete expression of the law of the conservation of
energy in Newton's third law of motion — namely, "the law of the
equality of action and reaction," or rather, in the second ex-
planation which Newton gave of that law. In fact, it was from
this law that Helmholtz deduced it in 1847. He showed that
the law of the equality of action and reaction, considered as a
law of nature, involved the impossibility of perpetual motion,
and the impossibility of perpetual motion is, in another form, the
conservation of energy.

At a meeting of the Academy of Science, at Berlin, 28th
March 1878, Du Bois-Reymond violently attacked Tail's con-
tention. The honour of having been the first to conceive of the
idea of energy and conservation was awarded to Leibniz.
Newton had no right to it, for he appealed to divine intervention

ENERGY IN GENERAL. 59

As for energetics, of which thermodynamics is only
a section, it is agreed that even if it cannot forthwith
absorb mechanics, astronomy, physics, chemistry, and
physiology, and build up that general science which
will be in the future the one and only science of
nature, it furnishes a preparation for that ideal state,
and is a first step in the ascent to definite progress.

Here I propose to expound these new ideas, in so
far as they contain anything universally accessible;
and in the second place, I propose to show their
application to physiology — that is to say, to point out
their role and their influence in the phenomena of
life.

Postulate: the Phenomena of Nature bring into
play only two Elements, Matter and Energy. — If we
try to account for the phenomena of the universe,
we must admit with most physicists that they
bring into play two elements, and two elements only
namely, matter and energy. All manifestations are
exhibited in one or other of these two forms. This,
we may say, is the postulate of experimental science.

Just as gold, lead, oxygen, the metalloids, and the
metals are different kinds of matter, so it has been
recognized that sound, light, heat, and generally, the
imponderable agents of the days of early physics, are

to set the planetary system on its path when disturbed by ac-
cumulated perturbations. On the other hand, Colding claims to
have drawn his knowledge of the law of conservation from
d'Alembert's principle. Whatever may be the theoretical
foundations of this law, we are here dealing with its experi-
mental proof. According to Tait, the proof can no more be
attributed to R. Mayer than to Seguin. The real modern
authors of the principle of the conservation of energy, who gave
an experimental proof of it, are Colding, of Copenhagen, and
Joule, of Manchester.

6o LIFE AND DEATH.

different varieties of energy. The first of these ideas
is older and more familiar to us, but it has not for that
reason a more certain existence. Energy is objective
reality for the same reason that matter is. The
latter certainly appears more tangible and more easily
grasped by the senses. But, upon reflection, we are
assured that the best proof of their existence, in both
cases, is given by the law of their conservation — that
is to say, their persistence in subsisting.

The objective existence of matter and that of
energy will therefore be taken here as a postulate of
physical science. Metaphysicians may discuss them.
We have but little room for such a discussion.

§ I. Matter.

It is certainly difficult to give a definition of
matter which will satisfy both physicists and meta-
physicians.

Mechanical Explanation of the Universe. Matter is
Mass. — Physicists have a tendency to consider all
natural phenomena from the point of view of mechanics.
They believe that there is a mechanical explanation
of the universe. They are always on the look out for
it, implicitly or explicitly. They endeavour to reduce
each category of physical facts to the type of the facts
of mechanics. They have made up their minds to see
nowhere anything but the play of motion and force.
Astronomy is celestial mechanics. Acoustics is the
mechanics of the vibratory movements of the air or of
sonorous bodies. Physical optics has become the
mechanics of the undulations of the ether, after having
been the mechanics of emission — a wonderful

ENERGY IN GENERAL. 6l

mechanics which represents exactly all the pheno-
mena of light, and furnishes us with a perfect objective
image of it. Heat, in its turn, has been reduced to a
mode of motion, and thermodynamics claims to em-
brace all its manifestations. As early as 1812, Sir
Humphry Davy wrote as follows: — "The immediate
cause of heat is motion, and the laws of transmission
are precisely the same as those of the transmission
of motion." From that time forth, this conception
developed into what is really a science. The constitu-
tion of gases has been conceived by means of two
elements — particles, and the motions of these particles,
determined in the strictest detail. And finally, in spite
of the difficulties of the representation of electrical and
magnetic phenomena after Ampere and before Maxwell
and Hertz, physicists have been able to announce in the
second half of the nineteenth century the unity of the
physical forces realized in and by mechanics. From
that time forth, all phenomena have been conceived
as motion or modes of motion, only differing essen-
tially one from the other in so far as motions may
differ — that is to say, in the masses of the moving
particles, their velocities, and their trajectories. The
external world has appeared essentially homogeneous ;
it has fallen a prize to mechanics. Above all, there
is heterogeneity in ourselves. It is in the brain,
which responds to the nervous influx engendered by
the longitudinal vibration of the air, by the specific
sensation of sound, which responds to the transverse
vibration of the ether by a luminous sensation, and in
general to each form of motion by an irreducible
specific sensation.

Forty years have passed since the mechanical ex-
planation of the universe reached its definite and

62 LIFE AND DEATH.

perfect form. It dominates physics under the name
of the theory of kinetic energy. The minds of men in
our own time are so strongly impregnated with this
idea that most scientists of ordinary culture get no
glimpse of the world of phenomena but by means of
this conception. And yet it is only an hypothesis.
But it is so simple, so intuitive, and appears to be sO
thoroughly verified by experiment, that we have
ceased to recognize its arbitrary and unnecessarily
contingent character. Many physicists from this
standpoint consider the kinetic theory as an im-
perishable monument.

However, as in the case of H. Poincare, the most
eminent physicists and mathematicians are not the
dupes of this system ; and without failing to recognize
the immense services which it has rendered to science,
they are perfectly well aware that it is only a system,
and that there may be other systems. Certain among
them, such as Ostwald, Mach, and Duhcm, believe
that the monument is showing signs of decay, and at
present the theory is opposed by another theory —
namely, the theory of energy.

The theory of energy is usually considered and pre-
sented as a consequence of the kinetic theory; but it
is perfectly independent of it, and it is, in fact, without
relying on the kinetic theory, without assuming the
unity of physical forces, which are combined in mole-
cular mechanics, that we shall expound the general
system.

This is not the point at issue for the moment. It is
not a question of deciding the reality or the merit of
this or that mechanical explanation ; it is a question
of something more general, because upon it depends
the idea of matter. It is a question of knowing if

ENERGY IN GENERAL. 63

there are any explanations other than mechanical.
The illustrious English physicist, Lord Kelvin, does
not seem willing to admit this. "I am never satisfied,"
he said, in his Molecular Mechanics, " until I have
made a mechanical model of the object. If I can
make this model, I understand ; if I cannot, I do not
understand."

This tendency of so vigorous a mind to be con-
tent only with mechanical explanations, has been
that of the majority of scientific men up to the
present day, and from it has arisen the scientific idea
of matter.

What is matter, in fact, to the student of mechanics?
It is mass. All mechanics is constructed of masses
and forces. Laplace said: " The mass of a body is the
sum of its material points." To Poisson, mass is the
quantity of matter of which a body is composed.
Matter is therefore confused with mass. Now, mass
is the characteristic of the motion of a body under the
action of a given force ; it defines obedience or resist-
ance to the causes of motion ; it is the mechanical
parameter; it is the co-efficient proper to every mobile
body; it is the first invariant of which a conception
has been established by science.

In fact, the word matter appears to be used in
other senses by physicists, but this is only apparently
so. They have but broadened the idea of the
mechanicians. They have characterized matter by
the whole series of phenomenal manifestations which
are proportional to mass, such as weight, volume,
chemical properties — so that we may say that the
notion of matter does not intervene scientifically with
a different signification from that of mass.

Two kinds of Matter. Ponderable and Imponder-

64 LIFE AND DEATH.

able. — In physics we distinguish between two kinds
of matter — ponderable, obeying the law of universal
attraction or weight, and imponderable matter or
ether, which we assume to exist and to escape the
action of that force. Ether has no weight, or ex-
tremely little weight. It is material in so far as it
has mass. It is its mass which confers existence on
it from the mechanical point of view — a logical ex-
istence, inferred from the necessity of explaining the
propagation of heat, light, or electricity.

It may be observed that the use of mass really
comes to bringing another element, force, to intervene,
and we shall see that force is connected with energy ;
thus it comes to defining matter indirectly by energy.
The two fundamental elements are not therefore
irreducible; on the contrary, they should be one and
the same thing.

Energy is the only Objective Reality. — This fusion
into one will become more evident still when we
examine the different kinds of energy, each of which
exactly corresponds to one of the aspects of active
matter. Shall we define matter by extension, by the
portion of space it occupies, as certain philosophers
do? The physicist will answer that space is only
known to us by the expenditure of energy necessary
to penetrate it (the activity of our different senses).
And then what is weight? It is energy of position
(universal attraction). And so with the other attri-
butes. So that if matter were separated from the
energetic phenomena by means of which it is revealed
to us — weight or energy of position, impenetrability
or energy of volume, chemical properties or chemical
energies, mass or capacity for kinetic energy — the very
idea of matter would vanish. And that comes to

ENERGY IN GENERAL. 65

saying that fundamentally there is only one objective
reality, energy.

Philosophical Point of View. — But from the philo-
sophical point of view are there objective realities?
That is a wider question which throws doubt upon
matter itself, and which it is not our place to investi-
gate here. A metaphysician may always discuss and
deny the existence of the objective world. It may- be
maintained that man knows nothing beyond his
sensations, and that he only objectivates them and
projects them outside himself by a kind of hereditary
illusion. We must avoid taking sides in all these
difficulties. Physics for the moment ignores them —
i.e., postpones their consideration.

In a first approximation we agree to consider
ponderable matter only. Chemistry acquaints us
with its different forms. They are the different
simple bodies, metalloids, metals, and the compound
bodies, mineral or organic. Hence we may say that
chemistry is the Jiistory of the transformations of
matter. From the time of Lavoisier this science has
followed the transformations of matter, balance in
hand, and ascertains that they are accomplished
without change of weight.

Law of the Conservation of Matter. — Imagine a
system of bodies enclosed in a closed vessel, and the
vessel placed in the scale of a balance. All the
chemical reactions capable of completely modifying
the state of this system have no effect upon the scale
of the balance. The total weight is the same before,
during, and after. It is precisely this equality of
weight which is expressed in all the equations with
which treatises on chemistry are filled.

From a higher point of view we recognize here, in

66 LIFE AND DEATH.

this law of Lavoisier or of the conservation of weight,
the verification of one of the great laws of nature
which we extend to every kind of matter, ponderable
or not. It is the law of the conservation of matter,
or again, of the indestructibility of matter — " Nothing
is lost, nothing is created, all is transformation." This
is exactly what Tait held, this impossibility of creating
or destroying matter which at the same time is a
proof of its objective existence. This indestructibility
of ponderable matter is at the same time the funda-
mental basis of chemistry. Chemical analysis could
not exist if the chemist were not sure that the contents
of his vessel at the end of his operations ought to be
quantitatively, that is to say by weight, the same as at
the beginning, and during the whole course of the
experiment.^

§ 2. Energy.

TJie Idea of Energy Derived front the Kinetic
Theory. — The notion of energy is not less clear than
the notion of matter, it is only more novel to our
minds. We are led to it by the mechanical conception
which now dominates the whole of physics, the kinetic
conception, according to which in the sensible universe
there are no phenomena but those of motion. Heat,
sound, light, with all their manifestations so complex
and so varied, may, according to this theory, be
explained by motion. But then, if outside the brain
and the mind which has consciousness and which
perceives. Nature really offers us only motion, it
follows that all phenomena are essentially homo-

^ It must be added that the absolute rigour of this law has
been called in question in recent researches. It would only
have an approximate value.

ENERGY IN GENERAL. 67

geneous among one another, and that their apparent
heterogeneity is only the result of the intervention of
our sensorium. They differ only in so far as move-
ments are capable of differing — that is to say, in
velocity, mass, and trajectory. There is something
fundamental which is common to them and this quid
commune is energy. Thus the idea of energy may be
derived from the kinetic conception, and this is the
usual method of exposition.

This method has the great inconvenience of causing
an idea which lays claim to reality to depend upon an
hypothesis. And besides that, it gives a view of it
which may be false. It makes of the different forms
of energy something more than varieties which are
equivalent to one another. It makes of them one and
the same thing. It blends into one the modalities of
energy and mechanical energy. For the experimental
idea of equivalence, the kinetic theory substitutes the
arbitrary idea of the equality, the blending, and the
fundamental homogeneity of phenomena. This no
doubt is how the founders of energetics, Helmholtz,
Clausius, and Lord Kelvin understood things. But a
more attentive study and a more scrupulous deter-
mination not to go beyond the teaching of experiment
should compel us to reform this manner of looking at
it. And it is Ostwald's merit that, after Hamilton, he
insisted on this truth — that the various kinds of
physical magnitudes furnished by the observation of
phenomena are different and characteristic. In par-
ticular, we may distinguish among them those which
belong to the order of scalar magnitudes and others
which are of the order of vector magnitudes.

The Idea of Energy derived from the Connection
of Phenomena. — The idea of energy is not absolutely

68 LIFE AND DEATH.

connected with the kinetic theory, and it should not
be exposed therefore to the vicissitudes experienced
by that theory. It is of a higher order of truth. We
can derive it from a less unsafe idea, namely that of
the connection of natural phenomena. To conceive it
we must get accustomed to this primordial truth, that
there are no pJienoinena isolated in time and space.
This statement contains the whole point of view of
energetics.

The physics of early days had only an incomplete
view of things, for it considered phenomena in-
dependently the one of the other.

Phenomena for purposes of analysis were classed in
separate and distinct compartments: weight, heat,
electricity, magnetism, light. Each phenomenon was
studied without reference to that it succeeded or that
which should follow. Nothing could be more artificial
than such a method as this. In fact, there is a
sequence in everything, everything is connected up,
everything precedes and succeeds in nature — in nature
there are only series. The isolated fact without
antecedent or consequent is a myth. Each
phenomenal manifestation is in solidarity with
another. It is a metamorphosis of one state of
things into another. It is transformation. It implies
a state of things anterior to that which we are
observing, a phenomenal form which has preceded
the form of the present moment.

Now there exists a link between the anterior state
and the succeeding state — that is to say, between the
new form which is appearing and the preceding form
which is disappearing The science of energy shows
that something has passed from the first condition to
the second, but covering itself as it were with a new

ENERGY IN GENERAL. 69

garment; in a word, that something active and
permanent subsists in the passage from one condition
to another, and that what has changed is only the
aspect, the appearance.

This constant something which is perceived beneath
the inconstancy and the variety of forms, and which
circulates in a certain manner from the antecedent
phenomenon to its successor, is energy.

But still this is only a very vague view, and it may
seem arbitrary. It may be made more exact by
examples borrowed from the different categories of
natural phenomena. There are energetic modalities
in relation with the different phenomenal modalities.
The different orders of phenomena which may be
presented — mechanical, chemical, thermal, electrical —
give rise to corresponding forms of energy.

When to a mechanical phenomenon succeeds a
mechanical, thermal, or electrical phenomenon, we
say, embracing transformation in its totality, that
there has been a transformation of mechanical energy
into another form of energy, mechanical, thermal, or
electrical, etc.

This idea becomes more precise if we examine
successively each of these cases and the laws which
regulate them.

§ 3. Mechanical Energy.

Mechanical energy is the simplest and the oldest
known.

Mechanical Elements : Time, Space, Force, Work.
Power. — Mechanical phenomena may be considered
under two fundamental conditions — time and space,

70 LIFE AND DEATH.

which are, in a measure, logical elements, to which
may be joined a third element, itself experimental,
having its foundations in our sensations — namely,
force, zvork, ox poiver.

The ideas of force, work, and power, are drawn from
the experience man has of his muscular activity.
Nevertheless the greatest mathematical minds from
from Descartes to Leibniz have been obliged to define
and explain them clearly.

Force. — The prototype of force is weight, universal
attraction. Experiment shows us that every body
falls as long as no obstacle opposes its fall. This is
so universal a property of matter that it serves to
define it. The force, weight, is therefore the name
given to the cause of the fall of the bodies.

Force in general is the cause of motion. Hence
force exists only in so far as there is motion. There
would be no force without action. This is Newton's
point of view. It did not prevail, and was not the
point of view of his successors. The name of force
has been given not only to the cause which produces
or modifies motion, but to the cause which resists and
prevents it. And then not only have forces in action
been considered (dynamics), hvX forces at r^j/ (statics).
Now, to Newton there was no statics. Forces do not
continue to exist when they produce no motion ; they
are not in equilibrium, they are destroyed.

The idea of force therefore is a metaphysical idea
which contains the idea of cause. But it becomes
experimental immediately it is looked upon as resist-
ing motion, according to the point of view of Newton's
opponents. Its foundations lie in the muscular
activity of man.

Man can support a burden without bending or

ENERGY IN GENERAL. 7I

moving. This burden is a weight — that is to say, a
mass acted on by the force of weight Man resists
this force so as to prevent its effect. If it were not
annihilated by man's effort, this effect would be the
motion or the fall of the heavy body. The effort and
the force are thus in equilibrium, and the effort is
equal and opposite to the force. It gives to the man
who exercises it the conscious idea oi force. Thus we
know of force through effort. Every clear idea that
we can have of force springs from the observation of
our muscular effort.

The notion of force is thus an anthropomorphic
notion. When an effect is produced in nature outside
human intervention, we say that it is by something
analogous to what in man is effort, and we give to this
something a name which is also analogous, namely
force. To give a name to effort diUd to compare
efforts in magnitude, we need not know all about
them, nor need we know in what they essentially
consist, of what series of physical, chemical, and
physiological actions they are the consequence. And
so it is with force. It is a resistance to motion or
the cause of motion. This cause of motion may be
an anterior motion (kinetic force). It may be an
anterior physical energy (physical and chemical
forces).

Forces are measured in the C.G.S. system by com-
paring them with the unit called the Dyne.^ In
practice they are compared with a much larger unit —
the gramme, which is the weight, the force acting on
a unit of mass of one centimetre of distilled water at
a temperature of 4^" C.

1 The dyne is the force which applied to the unit of mass
produces a unit of acceleration.

6

72 LIFE AND DEATH.

Work. — The muscular activity of man may be
brought into play in yet another manner. When we
employ workmen, as Carnot said in his Essai sur
reqiiilibre et le inouvement, it is not a question of
" knowing the burdens that they can carry without
moving from their position," but rather the burdens
that they can carry from one point to another. For
instance, a workman may have to lift the water from
the bottom of a well to a given height, and the case is
the same for the animals we employ. " This is what
we understand by force when we say that the force of
a horse is equal to the force of seven men. We do
not mean that if seven men were pulling in one
direction and the horse in another that there would be
equilibrium, but that in a piece of work the horse
alone would lift, for example, as much water from the
bottom of a well to a given height as the seven men
together would do in the same time." ^

Here, then, we have to do with the second form of
muscular activity, which is called in mechanics, "work"
— at least, if in the preceding quotation we attach no
particular importance to the words " in the same
time," and retain the employment of muscular activity
only "under constant conditions." Mechanical work
is compared with the elevation of a certain weight to a
certain height. It is measured by the product of the
force (understood in the sense in which it was used
just now — that is to say, as causing or resisting motion)
and the displacement due to this motion. The unit is
the Kilogrammetre — that is to say, the work necessary
to lift a weight of one kilogramme to the height of
one metre.

^ These words spoil the statement, for time has nothing to
do with it.

ENERGY IN GENERAL. 73

It will be remarked that the idea of time does not
intervene in our estimation of work. The notion of
work is independent of the ideas of velocity and
time. " The greater or less time that we take to do
a piece of work is of no more assistance in measur-
ing its magnitude than the number of years that
a man may have taken to grow rich or to ruin him-
self can help to estimate the present amount of his
fortune."

Going back to Carnot's comparison, an employer
who employed his workmen only on piece-work, — that
is to say, who would only care about the amount of
work done, and would be indifferent to the time that
they took over it, — would be at the same point of view
as the advocates of the mechanical theory. M.
Bouasse, whom we follow here, has remarked that this
idea of mechanical work may be traced back to
Descartes. His predecessors, and Galileo in par-
ticular, had quite a different idea of the way in which
mechanical activity should be measured ; and so,
among the mathematicians of the eighteenth century,
Leibniz and, later, John Bernoulli were almost alone
in looking at it from this point of view.

Energy. — Work thus understood is mechanical
energy. It represents the lasting and objective effect
of the mechanical activity independent of all the cir-
cumstances under which it was carried out. The
same work may be done under very different con-
ditions of time, velocity, force, and displacement.
It is therefore the permanent element in the variety of
mechanical aspects. Work, for example, in the
collision of bodies when the motion of a body appears
to be destroyed on impact with another, reappears as
indestructible vis viva. This, then, is exactly what

74 LIFE AND DEATH.

we call energy; and if we agree to give it this name,
we may say that the conservation of energy is
invariable throughout all mechanical transforma-
tions.

Distinction between Work and Force, and between
Energy and Work. — The history of mechanics shows
us what trouble has been taken and what efforts have
been made to distinguish work (now mechanical
energy) from force.

It is worth while insisting on this distinction. It
could be easily shown that force has no objective ex-
istence. It has no duration, no permanence. It does
not survive its effect, motion. There is no conserva-
tion of force. It passes instantly from infinity to
zero. It is a vectorial inagnitjide — that is to say, it
involves the idea of direction. Work, on the other
hand, is the real element; it is a scalar magnitude
involving the idea of opposite directions, indicated by
the signs + and - . Work and force are hetero-
geneous magnitudes. Energy, and this is the only
characteristic by which it is distinguished from work,
is an absolute magnitude to which we may not even
give opposite signs.

An example may perhaps throw these characteristics
into relief — namely, the hydraulic press. We have on
the platform exactly the work which has been done
on the other side. The machine has only made it
change its form. On the contrary, the force has been
infinitely multiplied. We may, in fact, consider an
infinite number of surfaces equal to that of a small
piston, placed and orientated at will within the liquid ;
each, according to Pascal's principle, will support a
pressure equal to that which is exercised. As soon as
we cease to support it, this infinity falls at once to zero.

ENERGY IN GENERAL. 75

Now what real thing could pass instantly from infinity
to zero?

That skilful and very able physiologist, M. Chauveau,
has endeavoured to use the same term energy of con-
traction for the two phenomena of effort (force) and
work. It seems, however, from the point of view of
the expenditure imposed on the organism, that these
two modes of activity, static contraction (effort), and
dynamical contractiott (work), may be, in fact, perfectly
comparable. But although this manner of conceiving
the phenomena may certainly be exact, and may be
of great value, the idea of force must none the less
remain distinct from that of work. The persistence
of the author in violating established custom in this
connection has prevented him from enabling mechani-
cians and even some physiologists to understand and
accept very useful truths.

Power. — The idea of mechanical /^zt/^r differs from
those of force and work. The idea of time must
intervene. It is not sufficient, in fact, in order to
characterize a mechanical operation, to point to the
task accomplished. It may be necessary or useful to
know how much time it required. This is true,
especially when we are concerned with the circum-
stances as well as the results of the performance of
the work; and this is the case when we wish to
compare machines. We say that the machine which
does the work in the . shortest space of time is
the most powerful. The unit of power is the Kilo-
grammetre-second — that is to say, the power of a
machine which does a kilogrammetre in a second. In
manufactures we generally employ a unit 75 times
greater than this — a horse-power. This is the power of
a machine which does 75 kilogrammetres a second.

76 LIFE AND DEATH.

In the electrical industry we measure by kilozvatts^
which are equivalent to 1.36 horse power, or by a watt,
a unit a thousand times smaller.

Let us add that the power of a machine is not an
absolute and permanent characteristic of the machine.
It depends on the circumstances under which the
work is carried out, and that is why, in particular, we
cannot appreciate the power of the human machine in
comparison with industrial machines. Experience
has shown that the mechanical power of living beings
depends upon the nature of the work they are doing.
In this connection we may mention some very inter-
esting experiments communicated to the Institute, in
the year VI., by the celebrated physicist, Coulomb. A
man of the average weight of 70 kilogrammes was
made to climb the stairs of a house 20 metres high.
He ascended at the rate of 14 metres a minute, and
he performed this daily task for four effective hours.
This work was equivalent to 235,000 kilogrammetres.
But if, instead of climbing without a burden, the same
man had had to carry a load, the result would have
been quite different. Coulomb's workman took up
six loads of wood a day to a height of 12 metres
in ^6 journeys, corresponding to a maximum
work of 109,000 instead of 235,000 kilogrammetres.
The mechanical power of the human machine
thus varied in the two cases in the ratio of 235
to 109.

The Two Aspects of Mechanical Energy: Kinetic
and Potential, — Energy, or mechanical work, may
present itself in two forms — kinetic energy, corre-
sponding to the mechanical phenomenon which has
really taken place, and potential energy, or the energy
of reserve.

ENERGY IN GENERAL. 77

A body which has been raised to a certain
height will, if it be let fall, perform work which
can be exactly measured in kilogrammetres by the
product of its weight into the height it falls. Such
work may be utilized in many ways. In this way,
for instance, public clocks are worked. Now, as long
as the clock-weight is raised and not let go, and
as long as it 'is motionless, the physics of early
days would say that there is nothing to discuss;
the phenomenon is the fall ; it is going to take
place, but at the present moment there has been
no fall.

In energetics we do not reason in this way. We
say that the body possesses a capacity for work which
will be manifested when the opportunity arises, a
storage of energy, a virtual or potential energy^ or
again, an energy of position, which will be transformed
into actual energy or real work as soon as the body
falls.

Let us ask whence this energy arises. It proceeds
from the previous operation which has raised the
weight from the surface of the soil to the position it
occupies. For example, if it is a question of the
weights of a public clock, which, by its fall, will develop
in 15 days the work that is necessary to turn the
wheels, to strike the bell, and to turn the hands,
this work ought to bring to our minds the exactly equal
and opposite work done by the clockmaker, who has
to carry the clock-weight and to lift it up from the
ground to its point of departure. The work of the
fall is the faithful counterpart of the work of elevation.
The phenomenon has therefore in reality two phases.
We find in the second exactly what was put into the
first, the same quantity of energy — ?>., the same work,

78 LIFE AND DEATH.

Between these phases comes tlie intermediary phase
of which we say that it is a period of virtual or poten-
tial energy. This is a way of remembering in some
measure the preceding phenomenon — i.e., the work of
lifting up, and of indicating the phenomena which will
follow — ie., the work of the fall. And thus we connect
by our thoughts the present situation with the ante-
cedent and with the consequent position, and it is
from this consideration of continuity alone that the
conception of energy springs — that is to say, of some-
thing which is conserved and is found to be permanent
in the succession of phenomena. This energy of
which we lose no trace does not appear to us new
when it is manifested. Our imagination eventually
materializes the idea of it. We follow it as a real
thing, having an objective existence, which is asleep
during the latent potential period, and is revealed or
manifested later.

Among other examples, that of the coiled spring
which is unwound is particularly suitable for show-
ing this fundamental character of the idea of
mechanical energy, an idea which is the clearest
of all. Machines are only transformers and not
creators of mechanical energy. They only change
one form into another.

In the same way, too, a stream of water or the
torrent of a mountainous region may be utilized for
setting in motion the wheels and the turbines of the
factories situated in the valley. Its descent produces
the mechanical work which would be a creation ex
nihilo if we do not connect the phenomenon with its
antecedents. We look on it as a simple restitution, if
we think of the origin of this water which has been
transported and lifted in some way to its level by the

ENERGY IN GENERAL. 79

play of natural forces — evaporation under the action
of the sun, the formation of clouds, transport by winds,
etc. And we here again see that a complex energy
has been transformed, in its first phenomenal con-
dition, into potential energy, and that this potential
energy is always expended in the second phase with-
out loss or gain.

The Diffe>ent Kinds of Mechanical Energy ; of
Motion, of Position. — There are as many forms of
energy as there are distinct categories of phenomena
or of varieties in these categories. Physicists dis-
tinguish between two kinds of mechanical energy —
energy of motion and energy of position. The energy
of position presents several variants — energy of dis-
tance, which corresponds to force: of this we have just
spoken ; energy of surface, which corresponds to par-
ticular phenomena of surface tension ; and energy of
volume which corresponds to the phenomena of pressure.
Energy of motion, kinetic energy, is measured in two
ways: as work (the product of force and displacement,
W =yj-) or as vis viva (half the product of the mass

ini>^
into the square of the velocity U = ^•

^ We therefore notice that the measures of force and work
bring in mass, space, and time. The typical force, weight, is
given by w — mg. On the other hand, we have by the laws of

IS 2 S

falling bodies v=gt; s = \f[t'^; whence,^— -, ; «/ = /« — ^;or, if

F be the force, M the mass, L the space described, and T the

time, we have F = MLT~^, which expresses what are called the

dimensions of the force — that is to say, the magnitudes with their

degree, which enter into its expression. We may thus easily

obtain the dimensions of work : —

imp'
Work = / X s= = M L2 T--.

80 LIFE AND DEATH.

§ 4. Thermal Energy.

In the elements of physics it is nowadays taught
that mechanical work may be transformed into heat,
and reciprocally that heat may be transformed into
mechanical work. Friction, impact, pressure, and
expansion destroy or annihilate the mechanical energy
communicated to a body or to the organs of a
machine. With the disappearance of motion we
note the appearance of heat. Examples abound.
The tyre of a wheel is heated by the friction of the
road. Portions of steel are warmed by the impact
with stone, as in the old flint and steel. Two pieces
of ice were melted by Davy, who rubbed them one
against the other, the external temperature being
below zero. The boiling of a mass of water caused
by a drill was noticed by Rumford in 1790, during
the manufacture of bronze cannon. Metal, beaten on
an anvil, is heated. A leaden ball flattened against a
resisting obstacle shows increase of temperature carried
to the point of fusion. Finally, and symbolically, we
have the origin of fire in the fable of Prometheus, by
rubbing together the pieces of wood which the Hindoos
called pramantJia. Correlation is constant between
the thermal and mechanical phenomena, a correlation
that becomes evident as soon as observers have ceased
to restrict themselves to the determination in isolation
of the one fact or the other. There is never any real
destruction of heat and motion in the true sense of the
word ; what disappears in one form appears again in
another; just as if something indestructible were ap-
pearing in a series of successive disguises. This
impression is translated into words when we speak

ENERGY IN GENERAL. 8l

of the metamorphosis of mechanical into thermal
energy.

The Mechanical Equivalent of Heat, — The inter-
pretation assumes a remarkable character of precision,
which at once strikes the mind when physics applies
to these transformations the almost absolute accuracy
of its measurements. We then find that the rate of
exchange is invariable. Transformations of heat into
motion, and of motion into heat, take place according
to a rigorous numerical law, which brings into exact
correspondence the quantity of each. Mechanical
effect is estimated, as we have seen, by work, that is in
kilogrammetres. Heat is measured in calories, the
calorie being the quantity of heat necessary to raise
from o°C to i°C a kilogramme of water (Calorie) or
one gramme of water (calorie). It is found that
whatever may be the bodies and the phenomena
which serve as intermediaries for carrying out this
transformation, we must always expend 425 kilo-
grammetres to create a Calorie, or expend 0*00234
Calories to create a kilogrammetre. The number 425
is the mechanical equivalent of the Calorie, or, as is
incorrectly stated, of the heat It is this constant fact
which constitutes the principle of the equivalence of heat
and of mechanical zvork.

§ 5. Chemical Energy.

We cannot yet actually measure chemical activity
directly, but we know that chemical action may give
rise to all other phenomenal modalities. It is their
most ordinary source, and it is to it that industries
appeal to obtain heat, electricity, and mechanical

82 LIFE AND DEATH.

action. In the steam engine, for instance, the work
that is received arises from the combustion of carbon
by the oxygen of the air. This gives rise to the heat
which vaporizes the water, produces the tension of the
steam, and ultimately produces the displacement of
the piston. The theory of the steam engine might be
reduced to these two propositions: chemical activity
gives rise to heat, and heat gives rise to motion ; or to
use the language to which the reader by now will be
accustomed, chemical energy is transformed into
thermal energy, and that into mechanical energy. It
is a series of phases and of instantaneous changes, and
the exchange is always affected according to a fixed
rate.

The Measurement of Chemical Energy. — Our know-
ledge of chemical energy is less advanced than that of
the energies of heat and sensible motion. We have
not yet reached the stage of numerical verifications.
We can only therefore affirm the equivalence of
chemical and thermal energies without the aid of
numerical constants, because we do not yet, in the
present state of science, know how to measure
chemical energy directly. Other known energies are
always the product of two factors : the mechanical
energy of position, or work, is measured by the
product of the force y^ and the displacements; work
=fs ; the mechanical energy of motion, U = | mv^, is
measured by the product of the mass into half the
square of the velocity. Thermal energy is measured
by the product of the temperature and the specific
heat; electric energy by the product of the quantity
of electricity (in coulombs) and of the electromotive
force (in volts). As for chemical energy, we guess
that it may be valued directly according to Berthollet's

ENERGY IN GENERAL. 83

system, adopted by the Norwegian chemists, Guldberg
and Waage, by means of the product of the masses
and of a force, or co-efficient of affinity, which depends
on the nature of the substances which are brought to-
gether, on the temperature, and on the other physical
circumstances of the reaction. On the other hand,
the researches of M. Berthelot enable us in many
cases to obtain an indirect valuation in terms of the
equivalent heat.

Its Tzvo Forms. — It is interesting to note that
chemical energy may also be regarded from the two
states of potential and kinetic energy. The coal-
oxygen system, to burn in the furnace of the steam
engine, must be primed by preliminary work (local
ignition), just as the weight that is raised and left
motionless at a certain height requires a small
effort to be detached from its support. When this
condition is fulfilled, energy is at once manifest.
We must admit that it existed in the latent state, in
the state of chemical potential energy. Under the
impulse received, the carbon combines with the
oxygen and forms carbonic acid, C + 2O becomes
CO2; potential energy is changed into actual chemical
energy, and immediately afterwards into thermal
energy. W^e should have only a very incomplete and
fragmentary view of the reality of things if we were
to consider this phenomenon of combustion in isolation.
We must consider it in connection with what has
actually created the energy which it is about to
dissipate. This antecedent fact is the action of the
sun upon the green leaf. The carbon which burns in
the furnace of the machine comes from the mine in
which it was stored in the form of coal — that is to say,
of a product which was vegetable in its primitive form,

84 ' LIFE AND DEATH.

and which was formed at the expense of the carbonic
acid of the air. The plant had separated, at the
expense of the solar energy, the carbon from the
oxygen to which it was united in the carbonic acid of
the atmosphere. It had created the system C + 2O.
So that the solar energy produces the chemical poten-
tial energy which was so long before it was utilized.
Combustion expends this energy in making carbonic
acid over again.

Materialization of Energy. — The fertility of the
idea of energy is therefore, as we see from all
these examples, due to the relations it establishes
between the natural phenomena of which it exhibits
the necessary relation, destroyed by the excessive
analysis of early science. It shows us that in the
world of phenomena there is nothing but trans-
formations of energy. And we regard these trans-
formations themselves as the circulation of a kind of
indestructible agent which passes from one form of
determination to another, as if it were simply putting
on a fresh disguise. If our intellect requires images
or symbols to embrace the facts and to grasp their
relation, it may introduce them here. It will materialize
energy, it will make of it a kind of imaginary being,
and confer upon it an objective reality. And for the
mind, as long as it does not become the dupe of the
phantom which it itself has created, this is an
eminently comprehensive artifice which enables us
to grasp readily the relations between phenomena
and their bond of affiliation.

The world appears to us then, as we said at the
outset, constructed with singular symmetry. It offers
to us nothing but transformations of matter and
transformations of energy ; these two kinds of meta-

ENERGY IN GENERAL. " 85

morphoses being governed by two laws equally
inevitable, the conservation of matter and the con-
servation of energy. The first of these laws expresses
the fact that matter is indestructible, and passes
from one phenomenal determination to another at
a rate of equivalence measured by weight; the
second, that energy is indestructible, and that it
passes from one phenomenal determination to another
at a rate of equivalence fixed for each category by
the discoveries of the physicists.

§ 6. Transformations of Energy.

The idea of energy has become the point of departure
of a science, Energetics, to the establishment of which
a large number of contemporary physicists, among
whom are Ostwald, Le Chatelier, etc., have devoted
their efforts. It is the study of phenomena, regarded
from the point of view of energy. I have said that it
claims to co-ordinate and to embrace all other sciences.

The first object of energetics should be the con-
sideration of the different forms of energy at present
known, their definition and their measurement. This
is what we have just done in broad outline.

In the second place, each form of energy must be
regarded with reference to the rest, so as to determine
if the transformation of this into that is directly
realizable, and by what means, and, finally, according
to what rate of equivalence. This new chapter is a
laborious task which would compel us to traverse the
whole field of physics.

Of this long examination we need only concern
ourselves here with three or four results which will be

86 LIFE AND DEATH.

more particularly important in the case of applications
to living beings. They refer to mechanical energy, to
the relations of thermal energy and chemical energy,
to the complete role of thermal energy, and finally to
the extreme adaptability of electrical energy.

1 . Transformation of Mechanical Energy, —
Mechanical energy may change into every other form
of energy, and all others can change into it, with but
one exception, that of chemical energy. Mechanical
effort does not produce chemical combination. What
we know of the part played by pressure in the re-
actions of dissociation seems at first to contradict
this assertion. But this is only in appearance. Pres-
sure intervenes in these operations only as preliminary
zvork ox priming, the purpose of which is to bring the
bodies into contact in the exact state in which they
must be for the chemical affinities to be able to enter
into play.

2. Transformation of Thermal Energy ; Priming.
— Thermal (or luminous) energy does not change
directly into chemical energy. In fact, heat and light
favour and even determine a large number of chemical
reactions; but if we go down to the foundation ot
things we are not long before we feel assured that
heat and light only serve in some measure for
priming for the phenomenon, for preparing the
chemical action, for bringing the body into the
physical state (liquid, steam) or to the degree of
temperature (400° C. for instance, for the combination
of oxygen and hydrogen) which are the preliminary
indispensable conditions for the entry upon the scene
of chemical affinities.

On the contrary, chemical energy may really be
transformed into thermal energy. We have an

ENERGY IN GENERAL. 87

instance of this in the reactions which take place
without the aid of external energy; and again, in
those very numerous cases which, such as the com-
bustion of hydrogen and carbon, or the decomposition
of explosives, the reactions continue when once primed.
I may make a further observation apropos of thermal
and photic energy. These are not two really and
essentially distinct forms, as was thought in the early
days of physics. When we consider things objectively,
there is absolutely no light without heat; light and
heat are one and the same agent. According as it is
at this or that degree of its scale of magnitude, it
makes a stronger impression on the skin (sensation of.
heat) or on the retina (sensation of light) of man and
animals. The difference may be put down to the
diversity of the work and not to that of the agent.
The kinetic theory shows us that the agent is
qualitatively identical. The words heat and light
only express the chance of the meeting of the radiant
agent with a skin and a retina. At the lowest degree
of activity this agent exerts no action on the termina-
tions of the thermal cutaneous nerves, nor on the
optic nerve-terminations. As this degree is raised
the former of these nerves are affected (cold, heat) and
are so to the exclusion of the nerves of vision. Then
they are both affected (sensation of heat and light),
and finally, beyond that, sight alone is affected. The
transformation of one energy into the other is there-
fore here reduced to the possibility of increasing or
decreasing the intensity of the action of this common
agent in the exact proportions suitable for passing
from one of the conditions to the other; and this is
easy when it is a question of going up the scale in the
case of light, and, on the contrary, it is not realizable

7

88 LIFE AND DEATH.

directly, that is to say without external assistance,
when it is a question of going down the scale again, in
the case of heat.

3, Heat a Degraded Form of Energy. — We have
seen that thermal energy is not directly transformed
into chemical energy. There is yet another restriction
in the case of this thermal energy if we study the laws
which govern the circulation and the transformations
of thermal energy; and the most important comes from
the impossibility of transporting it from a body at
a lower temperature to a body at a higher temperature.
On the whole, and because of these restrictions,
thermal energy is an imperfect variety of universal
energy, or, as the English physicists call it, a degraded
form.

4. Siviple Transformations of Electrical Energy. Its
Intermediary Roie. — On the other hand, electrical energy
represents a perfected and infinitely advantageous form
of this same universal energy, and this explains the vast
development of its industrial applications within less
than a century. It is not that it is better known than
the others in its nature and in the secret of its action.
On the contrary, there is more dispute than ever as to
its nature. To some, electricity, which is transported
and propagated with the speed of light, is a real flux
of the ether as was taught by Father Secchi, who
compared it to a current of water in a pipe. It would
do its work, just as the water of the mill does its
work by flowing over a wheel or through a turbine.
Electricity, like water in this case, would not be
an energy in itself, but a means of transporting
energy.

To others, such as Clausius, Hertz, and Maxwell, it
is not so; the electric current is not a transport of

ENERGY IN GENERAL. 8g

energy. It is a state of the ether of a peculiar,
specific kind, periodically produced (electric oscilla-
tion), and propagated with a speed of the order of
that of light.

However that may be, what constitutes the essential
peculiarity of electrical energy, and what causes its
value, is that it is an incomparable agent of trans-
formation. Every known form of energy may be
converted into it, and inversely, electrical energy may
be changed with the utmost facility into all other
energies. This extreme adaptability assigns to it
the part of an intermediary between the other less
tractable agents. Mechanical energy, for instance,
lends itself with difficulty to the production of light,
that is to say, to a metamorphosis into photic energy
(a variety of thermal energy). A fall of water cannot
be directly utilized for lighting purposes. The
mechanical work of this fall, which cannot be
exploited in its present form, serves to set in
motion in industrial lighting the installatiorfS, the
electric machines, and the dynamos which feed the
incandescent lamps. Mechanical work is changed
into electrical energy, and it, in its turn, into thermal
or photic energy. Electricity has here played the part
of a useful intermediary.

The last part of energetics must be consecrated to
the study of the general principles of this science.
These principles are two in number, the principle of
the conservation of energy^ or Mayer's principle, and
the principle of the transformation of energy, or
Carnot's principle. The doctrine of energy thus
reduces to two fundamental laws the multitude of
laws, often known as "general," to which natural
science is subject.

go LIFE AND DEATH.

§ 7. The Principle of the Conservation
OF Energy.

In all that precedes, the principle of conservation has
intervened at every step. In fact, the very idea of
energy is connected with the existence of this principle.
We first discover the idea in the work of the philo-
sophical mathematicians who established the founda-
tions of mechanics: — Newton, Leibniz, d'Alembert,
and Helmholtz ; or of inductive physicists such as
Lord Kelvin. Its experimental proof, sketched by
Marc Seguin and R. Mayer, is due to Colding and
Joule.

It is Independent of the Kinetic Theory. — Mayer's
law states that energy is indestructible; that all
phenomenality is nothing but a transformation of
energy from one form to another, and that this
transformation takes place either at equal values,
or rather, at a certain rate of equivalence. This is
what takes place when thermal energy is transformed
into mechanical energy (equivalent 425). This rate
of equivalence is fixed by the researches of physicists
for each category of energy.

It will be noticed that this law and this theory of
energy, which is always presented by authors of
elementary books as a consequence of the kinetic
theory, is quite independent of it. In the preceding
lines we have not even mentioned its name. We
have not assumed that all phenomena are movements
or transformations of movements, whether sensible or
vibratory; we have not affirmed that what was
passing from one phenomenal determination to
another was the vis viva of the motion, as is the case

ENERGY IN GENERAL. gi

in the impact of elastic bodies. No doubt the kinetic
theory affords us a very striking image of these truths
which are independent of it; but it may be false: and
the theory of energy which assumes the minimum of
possible hypotheses would yet be true.

It contains a great man^ other Principles. —
The principle of the conservation of energy contains
a large number of the most general principles of
science. It may be shown without much difficulty
that, for example, it contains the principle of the
inertia of matter, laid down by Galileo and Descartes;
that of the equality of action and reaction, due to
Newton ; and even that of the conserv^ation of matter,
or rather of mass, due to Lavoisier. And finally, it
contains the experimental law of equivalence con-
nected with the name of the English physicist Joule,
from which may be derived the Law of Hess and the
principle of the initial and final states which we owe
to Berthelot.

// iyivolves the Laiv of Equivalence. — Here we may
be content with noticing that the law of the conserva-
tion of energy involves the existence of relations of
equivalence between the different varieties. A certain
quantity of a given energy, measured, as we have
seen, by the product of two factors, is equivalent to a
certain fixed quantity of quite a different form of
energy into which it may be converted. The laws
which govern energetic transformations therefore con-
tain, from both the qualitative and the quantitative
points of view, all the connections of the phenomena
of the universe. To study these laws in their detail is
the task that physics must take upon itself.

The conversion one into the other of the different
forms of energy by means of equivalents is only a

92 LIFE AND DEATH.

possibility. It is subject, in fact, to all sorts of
restrictions, of which the most important are due to
the second principle.

§ 8. Carnot's Principle. Its Generality.

The second fundamental principle is that of the
transformations of equilibrium, or of the conditions
of reversibility, or again, Carnot's principle. This
principle, which first assumed a concrete form in
thermodynamics, has been very widely extended. It
has reached a degree of generality such that contem-
porary theoretical physicists such as Lord Kelvin, Le
Chatelier, etc., consider it the universal law of
physical, mechanical, and chemical equilibrium.

Carnot's principle contains, as was shown by G.
Robin, d'Alembert's principle of virtual velocities,
and according to physicists of to-day, as we have just
remarked, it contains the laws peculiar to physico-
chemical equilibrium. The application of this prin-
ciple gives us the differential equations from which
are derived numerical relations between the different
energies, or the different modalities of universal
energy.

Its Character. — It is very remarkable that we can-
not give a general enunciation of this principle which
by its revealing power has changed the face of
physics. This is because it is less a law, properly so
called, than a method or manner of interpreting the
relations of the different forms of energy, and par-
ticularly the relations of heat and mechanical energy.

Conversion of Work into Heat and Vice-versa. — The
conversion of work into heat is accomplished without
difficulty. For example, the hammering of a piece of

I

ENERGY IN GENERAL. 93

iron on an anvil may bring it to a red heat. A shell
which passes through an armour plate is heated, and
melts and volatilizes the metal all round the hole it
has made. By utilizing mechanical action under the
form of friction all energy can be converted into heat.

The inverse transformation of heat into work, on
the contrary, cannot be complete. The best motor
that we can think of, and a fortiori the best we can,
realize, can only transform a third or a fourth of the
heat with which it is supplied.

This is an extremely important fact. It is of in-
calculable importance to natural philosophy, and may
be ranked among the greatest discoveries.

Higher and Degraded Forms of Energy. — Of these
we may give an account by distinguishing among the
forms of universal energy higher forms, and lozver or
degraded forms. Here we have the principle of the
degradation of energy on its trial, and it may be
regarded as a particular aspect of the second principle
of energetics, or Carnot's principle. Mechanical
energy is a higher form. Thermal energy is a lower
form, a degraded form, and one which has degrees in
its degradation. Higher energy, in general, may be
completely converted into lower energy; for example,
work into heat : the slope is easy to descend, but it is
diflficult to retrace our steps ; lower energy can be
only partially transformed into higher energy, and the
fraction thus utilizable depends upon certain con-
ditions on which Carnot's principle has thrown con-
siderable light.

Thus, although in theory the thermal energy of a
body may have its equivalent in mechanical energy,
the complete transformation is only realizable from
the latter to the former, and not from the former to

94 I.IFE AND PEATH.

the latter. This is due to a condition of thermal
energy which is called temperature. The same
quantity of thermal energy, of heat, may be stored
in the same thermal body at different temperatures.
If this quantity of thermal energy is in a very hot
body we can utilize a large portion of it ; if it is in a
relatively cold body we can only convert a small
portion of it into mechanical work. Thus the value
of energy, — i.e., its capacity of being converted into
a higher and more useful form, — depends on tem-
perature.

The Capacity of Conversion depends on Temperature.
— The conversion of heat into work assumes two
bodies of different temperatures, the one warm and
the other cold ; a boiler and a condenser. Every
thermal machine conveys a certain amount of heat
from the boiler to the condenser, and what is not thus
carried is changed into work. This residue is only a
small fraction, a quarter, or at most a third of the
heat employed, and that, too, in the theoretically
perfect machine, in the ideal machine.

This output, this utilizable fraction depends on the
fall of temperature from the higher to the lower level,
just as the work of a turbine depends on the height
of the waterfall which passes through it. But it also
depends on the conditions of this fall, on the
accessory losses from radiation and conduction.
However, Carnot has shown that the output is the
same, and a maximum for the same fall of temperature,
whatever be the working agent (steam, hot air, etc.),
and whatever be the machine — provided that this
agent, this substance which works is not exposed to
accessory losses, that it is never in contact with a
body having temperature different to its own — or

ENERGY IN GENERAL. 95

ajain, that it is connected only with bodies im-
permeable to heat.

This is Carnot's principle in one of its concrete
forms.

A machine which realizes this condition, that the
agent (steam, alcohol, ether) is in relation, at all
phases of its function, with boidies which can neither '
take heat from it nor give heat to it, is a reversible
machine. Such a machine is perfect. The fraction
of heat that it transforms into motion is constant; it
is a maximum ; it is independent of the motor, of its
organs, of the agent : it accurately expresses the
transformability of the heat agent into a mechanical
agent under the given conditions.

The Degradation and Restoration of Energy. — The
fraction not utilized, that which is carried to the
condenser at a lower temperature, is degraded. It
can only be used by a new agent, in a new machine
in which the boiler has exactly the same temperature
as the condenser in the first machine, and the new
condenser has a lower temperature, and so on. The
proportion of utilizable energy thus goes on diminish-
ing. Its utilization requires conditions more and
more difficult to realize. The thermal energy loses its
potential and its value, and is further and further de-
graded as its temperature approaches that of the
surrounding medium.

The degraded energy, theoretically, has kept its
equivalent value but, practically, it is incapable of
conversion. However, it is shown in physics that it
can be raised and re-established at its initial level.
But for that purpose another energy must be utilized
and degraded for its benefit.

TJie End of the Universe. — What we have just

96 LIFE AND DEATH.

seen with respect to heat and motion is to some
degree true of all other forms of energy, as Lord
Kelvin has shown. The principle of the degradation
of energy is very general. Every manifestation of
nature is an energetic transformation. In each of
these transformations there is a degradation of energy —
i.e., a certain fraction is lowered and becomes less
easily transformable. So that the energy of the
universe is more and more degraded; the higher
forms are lowered to the thermal form, the latter
increasing at temperatures which become more and
more uniform. The end of the universe, from this
point of view, would then be unity of (thermal) energy
in uniformity of temperature.

Importance of the Idea of Energy in Physiology. —
I have said that the application of Carnot's principle
furnished numerical relations between the different
energetic transformations.

The science of living beings has not yet reached
that point of development at which it is possible for
us to obtain its numerical relations. However, the
consideration of energy and the principle of conserva-
tion has altered the outlook of physiology on many
questions which are of the highest importance.

The determination of the sources from which plants
and animals draw their vital energies; the mediate
transformation of chemical energy into animal heat in
nutrition, or into motion in muscular contraction ; the
chemical evolution of foods ; the study of soluble
ferments — all these questions are of considerable
importance when we wish to understand the
mechanisms of life. They are therefore depart-
ments of physiological energetics in which great
advances have already been made.

CHAPTER II.

ENERGY IN BIOLOGY.

§ I. Energy in Living Beings. — § 2. The First Law of Biological
Energetics: — All Vital Phenomena are Energetic Trans-'
formations.— § 3. Second Law : — The Origin of Vital
Energy is in Chemical Energy. Functional Activity and
Destruction.— § 4. Third Law:— The Final Form of
Energatic Transformation in the Animal is Thermal
Energy. Heat is an Excretum.

The theory of energy was thought of and utih'zed in
physiology before it was introduced into physics, in
which it has exercised such an extraordinary influence.
Robert Mayer was a physicist and a doctor. Helm-
holtz was equally at home in physiology and in physics.
From the outset both had seen in this new idea a
powerful instrument of physiological research. The
volume in which Robert Mayer expounded, in 1845,
his remarkable views on organic movement in relation
to nutrition, and Helmholtz' commentary leave us in
no doubt in this respect. The essay on the mechanical
equivalent of heat, of a more particularly physical
character, is six years later than the earlier work.

The Relations betzveen Energetics and Biology. —
The theory of energy is therefore only returning to
its cradle; and to that cradle it returns with all the
sanction of physical proof, as the most general theory

97

g8 LIFE AND DEATH.

ever proposed in natural philosophy, and the theory
least encumbered with hypotheses. It reduces all
particular laws to two fundamental principles — that
of the conservation of energy, which contains the
principles of Galileo and Descartes, of Newton, of
Lavoisier, Joule's law, Hess's law, and Berthelot's
principle of the initial and final states; and also
Carnot's principle, from which are deduced the laws
of physico-chemical and chemical equilibrium. These
two principles therefore sum up the whole of natural
science. They express the necessary relation of all
the phenomena of the universe, their uninterrupted
gentic connection, and their continuity.

A priori there would be little likelihood that a
doctrine, so universal and so thoroughly verified in
the physical world, could be restricted, and thus
be useless to the living world. Such a supposi-
tion would be contrary to the scientific method, which
always tends to the generalization and the explanation
of elementary laws. The human mind has always
proceeded thus : it has applied to the unknown
order of living phenomena the most general laws of
contemporary physics.

This application has been found legitimate, and has
been justified by experiment whenever it has been a
question of the laws or of the really fundamental or
elementary conditions of phenomena. It has, on the
other hand, however, been unfortunate when it has
stopped short of secondary characteristics. When we
now concede the subjection of living beings to these
general laws of energetics, we are following a
traditional method. There is no doubt that this
application is legitimate, and that experiment will
justify it a posteriori.

ENERGY IN BIOLOGY. 99'

I will therefore grant, as a provisional postulatCy
the consequences of which will have to be ultimately
justified, that the living and inanimate world alike
show us nothing but transformations of matter and
transformations of energy. The word phenomenon
will have no other signification, whatever be the
circumstances under which the phenomenon occurs.
The varied manifestations which translate the activity
of living beings thus correspond to transformations of
energy, to conversions of one form into another, in
conformity with the rules of equivalence laid down by
the physicists. This conception may be formulated
in the following manner: — TJie phenome)ia of life have
the same claim to be energetic metamorphoses as the
othe>r phenomena of nature.

This postulate is the foundation of biological
energetics. It may be useful to give some ex-
planation relative to the signification, the origin, and
the scope of this statement.

Biological energetics is nothing but general physi-
ology reduced to the principles that are common to all
the physical sciences. Robert Mayer and Helmholtz
gave the best description of this science, and laid
down its limits by defining it as " the study of the
phenomena of life regarded from the point of view
of energy."

§ I. Energy at play in Living Beings.
Common or Physical Energies. Vital
Energies.

Our first object will be to define and to enumerate the
energies at play in living beings ; to determine their
more or less easy transformations from one to another,

100 LIFE AND DEATH.

to bring to light the general laws which govern those
transformations, and finally to apply theai to the
detailed study of phenomena. This programme may
be divided into four parts.

In the physical world the specific forms of energy
are not numerous. When we have mentioned
mechanical, chemical, radiant (thermal and photic)
energies, electrical energy, with which is blended
magnetic energy, we have exhausted the catalogue of
natural agents.

But is this list for ever closed ? Are vital energies
comprised in this list ? These are the first questions
which we must ask ourselves.

The iatro-mechanical school, on a priori grounds
give an affirmative answer. No doubt there are in the
living organism many manifestations which are pure
physical manifestations of known energies, mechanical,
chemical, thermal, etc. But are all the manifestations
of the living being of this order ? Are they all, hence-
forth, reducible to the categories and varieties of energy
which are investigated in physics ? This is the claim
of the mechanical school. But the claim is rash. Our
fundamental postulate affirms, in principle, that uni-
versal energy is manifested in living beings; but, as a
matter of fact, there is no reason for the assertion that
it does not assume particular forms, according to the
circumstances peculiar to the conditions under which
they are produced.

These special forms of energy manifested in the con-
ditions suitable to living beings would swell the list
drawn up by the physicists. And it would not be the
first instance of an extension of this kind. The
history of science records many remarkable cases.
Scarcely a century has passed since we first heard of

ENERGY IN BIOLOGY. lOI

electrical energy. This discovery in the world of
energy, which took place, so to speak, before our
very eyes, of an agent which plays so large a part
in nature, clearly leaves the door open to other
surprises.

We shall therefore concede that there may be
other forms of energy at work in living beings than
those we already know in the physical world. This
reservation would enable us to discover at once the
essential characteristics by which vital phenomena
are henceforth reduced to universal physics, and
the purely formal differences still distinguishing
them.

If there arj really special energies in living beings,
our monistic postulate leads us to assert that these
energies are homogeneous with the others, and that
they do not differ from them more than they differ
among themselves. It is probable that some day
they will be discovered external to living bodies, if
the material conditions (which it is always possible to
imagine) are realized externally to them. And if we
must admit that the peculiarity of the medium is
such that these forms must remain indefinitely
peculiar to living beings, we may assert with every
confidence that these special energies do not obey
special laws. They are subject to the two funda-
mental principles of Robert Mayer and Carnot.
They are exchanged according to fixed laws with
the other physical forms of energies at present
known.

To sum up, then, we must establish three categories
in the forms of energy which express the phenomena
of vitality.

In the first place, most of these energies are those

102 LIFE AND DEATH.

which have already been studied and recognized m
general physics. They are the same energies :
chemical, thermal, mechanical, with their char-
acteristics of mutability, their lists of equivalents,
and their actual and potential states.

In the second place, it may happen, and it prob-
ably will happen, as it happened in the last century
in the case of electricity, that some new form of
energy will be discovered belonging to the universal
order as to the living order. This will be a conquest
of general physics as well as of biology.

And finally we may rigorously and provisionally
admit a last category of vital energies properly so
called.

It is difficult to give much precision to the idea of
vital energies properly so called.

It will be easier to measure them by means of
equivalents than to indicate their nature. Besides,
this is the ordinary rule in the case of physical agents.
We can measure them, although we know not what
they are.

Characteristics of Vital Energies. — We see why we
cannot exhibit with precision, a priori, the nature of
vital energies. In the first place, they are expreseed
by what takes place in the tissues in activity, and
this cannot at present be identified with the known
types of physical, chemical, and mechanical pheno-
mena. This is a first, intrinsic reason for not being
able to distinguish them readily, since what takes
place is not distinguished by the phenomenal appear-
ances to which we are accustomed.

There is a second, intrinsic reason. These vital
phenomena are intermediary, as we shall see, between
manifestations of known energies. They lie between

ENERGY IN BIOLOGY. I03

a chemical phenomenon which always precedes them,
and a thermal phenomenon which always follows
them. They are lost sight of, as it were, between
manifestations which strike our attention. Generally
speaking, intermediary energies often escape us
even in physics. Only the extreme manifestations,
are clearly seen. In the presence of the organism
we are, as it were, in electric lighting works which
are run by a fall of water, and at first we only
see the mechanical energy of the falling water,
of the turbine and dynamo at work, and the
photic energy of the lamps which give the light.
Electrical energy, an intermediary, which has only
a transient existence, does not impose itself on our
attention.

And so vital energies for this twofold reason, in-
trinsic and extrinsic, are not readily apparent. To
reveal them, the careful analysis of the physiologists
is required. They are acts, in most cases silent and
invisible, which we should scarcely recognize but by
their effects, after they have terminated in familiar,
phenomenal forms. This is, for example, what goes
on in the muscle in process of shortening, in the nerve
carrying the nervous influx, in the secreting gland.
And this is what constitutes the different forms of
energy which we call vital properties. M. Chauveau
and M. Laulanie use the phrase physiological work
to distinguish them, Vitdl energy would be prefer-
able. It better expresses the analogy of this special
form with the other forms of universal energy ; it
helps us better to understand that we must hence-
forth consider it as exchangeable by means of
equivalents with the energies of the physical world
just as they are exchangeable one with another.

104 life and death.

§ 2. First Law of Biological Energetics.

It is easy to understand, after these remarks, the
significance and the scope of this assertion which
contains the first principle of biological energetics —
namely, that the phenomena of life have the same
claim to be called energetic metamorphoses as the
other phenomena of nature.

Irreversibility of Vital Energies. — However, there
is one characteristic of vital energies which deserves
the closest attention. Their transformations have a
direction which is in some measure inevitable. They
descend a slope which they never re-ascend. They
appear to be irreversible. ' Ostwald has rightly in-
sisted on this fundamental characteristic, which no
doubt is not that of all the phenomena of the living
being without exception, but which is certainly that of
the most essential phenomena. There are reversible
phenomena in organisms ; there are energetic trans-
formations which may take place from one form of
energy to another, or vice versa. But the most
characteristic phenomena of vitality do not act in
this way. We shall presently see that most functional
physiological acts begin with chemical and end with
thermal action. The series of energetic transforma-
tions takes place in an inevitable direction, from
chemical to thermal energy. The order of succession
of ordinary energies is thus determined in the machine
of the organism, and therefore by the conditions of
the machine. The order of transformation of vital
energies is still more rigorously regulated, and the
phenomena of life evolve from childhood to ripened
years, and thence to old age, without a possible
return.

ENERGY IN BIOLOGY. I05

The laws of biological energetics are three in num-
ber. First of all, there is the fundamental principle
which we have just developed, and which is, so to
speak, laid down a pnori; and there are two other
principles, those established by experiment and
summing-up, as it were, the multitude of known
physiological effects. Of these two experimental
laws, one refers to the origin and the other to the
terviinatioti of the energies developed in living beings.

§ 3. Second Law of Biological Energetics. •

The Oigin of Vital Energy. — Vital energies have
their origin in one of the external or common energies
— not in any one we choose, as might be supposed,
but in one only: chemical energy. The third principle
will show us that they terminate in another energy or
a few others, also completely fixed.

It follows that the phenomena of life must appear
to us to be a circulation of energy which, starting from
one fixed point in the physical world, returns to that
world by a few points, also fixed, after a transient
passage through the animal organism.

Or more precisely, it is a transposition from the
realm of matter into the world of energy, of the idea
of the vital vortex of Cuvier and the biologists.
They defined life by its most constant property —
nutrition. Nutrition was exactly this current of
matter which the organism obtains from without by
alimentation, and which it throws out again by ex-
cretion ; and the even momentary interruption of
which, if complete, would be the signal of death.
The cycle of energy is the exact counterpart of
this cycle of matter.

I06 LIFE AND DEATH.

The second truth taught us by general physiology,
a truth which physiology learned from experiment, is
enunciated as follows : — The maintenance of life con-
sumes none of its energy. It borrows from the external
world all the energy which it expends, and borrows it in
the form of potential chemical energy. This is a trans-
lation into the language of energetics of the results
acquired in animal physiology during the last fifty years.
No comment is needed to exhibit the importance of
such a truth. It reveals the origin of animal activity.
It reveals the source from which proceeds that energy
which at some moment of its transformations in the
animal organism will be a vital energy.

The prinium movens of vital activity is, therefore,
according to this law, the chemical energy stored up
in the immediate principles of the organism.

Let us try to follow, for a moment, this energy
through the organism and to specify the circumstances
of its transformations.

Organic Functional Activity, and the Destruction of
Reserve-sttiff. — Let us suppose then, for this purpose,
that our attention is directed to a given limited part
of this organism, to a certain tissue. Let us seize
it, so to speak, by observation at a given moment,
and let us make an examination of the functional
activity starting from this conventional moment.
This functional activity, like all other vital pheno-
mena, will be the result, as we have just explained, of
a transformation of the potential chemical energy
contained in the materials held in reserve in the
tissue. This is our first perceptible fact. This
energy, when disengaged, will furnish to the vital
action the means by which it may be prolonged.
There is, then, a functional destruction. There is, at

ENERGY IN BIOLOGY. IO7

the beginning of the functional process, and by a
necessary effect of that very process, a liberation of
chemical energy ; and that can only take place by a
decomposition of the immediate principles of the
tissue, or, as we may say, by a destruction of organic
material. Claude Bernard insisted on this considera-.
tion, that the vital function is accompanied by a
destruction of organic material. " When a movement
is produced, when a muscle is contracted, when
volition and sensibility are manifested, when thought
is exercised, when a gland secretes, then the substance
of the muscles, of the nerves, of the brain, of the
glandular tissue, is disorganized, is destroyed, and is
consumed." Energetics enables us to grasp the
deeply-seated reason of this coincidence between
chemical destruction and the functional activity, the
existence of which Claude Bernard intuitively sus-
pected. A portion of organic material is decomposed,
is chemically simplified, becomes less complex, and
loses in this kind of descent the chemical energy
which it contained in its potential state. It is this
energy which becomes the very texture of the vital
phenomenon.

It is clear that the reserve of energy thus expended
must be replaced, because the organism remains in
equilibrium. Alimentation provides for this.

How does it provide for it? This is a question
which deserves detailed 'examination. We cannot
incidentally treat it in full; we can only indicate its
main features.

Hotv the supply of Reserve Stuff is kept up. — We
know that food does not directly replace the reserve
of energy consumed by the functional activity. It is
not its potential chemical energy which replaces.

I08 LIFE AND DEATH.

purely and simply, the energy brought into play,
consumed, or, better still, transformed in the active
organ, or tissue. Food as it is introduced, inert food,
does not, in fact, take up its place as it is, without
undergoing changes in that organ and that tissue, in
order to restore the status quo ante.

Before building up the tissue it will have undergone
various modifications in the digestive apparatus. It
will have also undergone changes in the circulatory
apparatus, in the liver, and in the very organ we are
considering. It is after all these changes that assimila-
tion takes place. It will find its place and will have
then passed into the state of reserve.

The food digested, modified, and finally incorporated
as an integral part in the tissue in which it will be ex-
pended, is therefore in a new state, differing more or
less from its state when it was ingested. It is a part
of the living tissue in the state of constitutive reserve.
Its potential chemical energy is not the same as that
of the food introduced. It may differ from it very
remarkably in consequence of sudden alterations.

We do not know for certain at the expense of what
category of foods this or that given organ builds up
its reserve stuff. There is a belief, for instance,
according to M. Chauveau, that the muscle does its
work at the expense of the reserve of glycogen which
it contains. The potential chemical energy of this
substance would be a source of muscular mechanical
energy. But we do not know exactly at the expense
of what foods, albumenoids, fats, or carbohydrates
the muscle builds up the reserve of glycogen expended
during its contraction. It is probable that it builds it
up at the expense of each of the three categories after
the various more or less simple alterations undergone

ENERGY IN BIOLOGY. lO^

by the materials in the digestive tube, the blood, the
liver, or other organs.

This building up of reserve stuff, the complement
and counterpart oi fiinciiotial destrucfion, is not chemi-
cal synthesis. It is, on the contrary, generally, and
on the whole, a simplification of the food that has
been introduced. This is true, at least as far as the
muscle is concerned. However, to this operation,
Claude Bernard has given the name of organising
synthesis, but the phrase is not a happy one. But
in no case was the eminent physiologist deceived
as to the character of the operation. "The organ-'
izing synthesis," says he, "remains internal, silent,
hidden in its phenomenal expression, gathering
together noiselessly the materials which will be
expended."

These considerations enable us to understand the
existence of the two great categories into which the
eminent physiologist divides the phenomena of animal
life: the phenomena of the destruction of reserve-
stuff zoxvQs^ond'mg to functional facts — that is to say
expenditures of energy; and i\\Q plastic p/ieno7nena of
the building-up of reserves of organic regeneration, cor-
responding \o functional repose — i.e., to the supply of
food to the tissues.

Distinction betiveen Active Protoplasm and Reserve-
stuff. — If it is not exactly in these terms that Claude
Bernard formulated this fruitful idea, it is at any
rate in this way that it is to be interpreted. This
can be done by giving it a little more precision.
We apply more rigorously than that great physio-
logist the distinction drawn by himself between really
active and living protoplasm and the reserve-stiff
which it prepares. To the latter is restricted the

115 LIFE AND DEATH.

destruction by the functional activity and the building
up by repose.

The classification of Claude Bernard is strictly true
for reserve-stuff. It is easy to criticize the wavering
and, as it were, dimly groping expressions in
which the celebrated physiologist has shrouded his
ideas. The old adage will excuse him: Obscuritate
renint verba obscurantur. In the depths of his ignor-
ance he had a flash of genius ; perhaps he did not find
the definitive and, as it were, clearly-cut formula de-
fining what was in his mind. But, in this respect, he
has left his successors an easy task.

TJie Lazv of Functional Assiviilation, — The progress
of physiological knowledge compels us therefore to
distinguish in the constitution of anatomical elements
two parts — the materials oi reserve-stuff -a-wA the really
active and living protoplasm. We have just seen how
the reserve-stuff behaves, alternately destroyed by
functional activity, and built up afterwards by the
ingestion of food, followed by the operations of di-
gestion, elaboration, and assimilation. It remains to
ask how this really living and protoplasmic matter
behaves. Does it follow the same law? Is it de-
stroyed during the functional activity, and is it after-
wards replaced ? As to this we can express no
opinion. M, le Dantec fills a gap in our knowledge,
in this respect, by an hypothesis. He assumes that
this essentially active matter grows during functional
activity, and is destroyed during repose. This is what
he calls the law of functional assimilation. The
protoplasm would therefore behave in an exactly
contrary manner to the reserve-stuff. It will be its
counterpart. But this is only an hypothesis which,
in the present state of our knowledge, cannot be

ENERGY IN BIOLOGY. Ill

verified by experiment. We are at liberty to
assert either that the protoplasm increases by
functional activity or that it is destroyed. Neither
the arguments nor the objections pro or con have any
decisive value. The facts alleged on either side are
capable of too many interpretations.^

The only favourable argument (not demonstrative)
is furnished by energetics. It is this. The re-building
of the protoplasm is not like the organization of reserve-
stuff, a slightly complicated or even simplified pheno-
menon, as happens in the case of the reserve of
muscular glycogen. The glycogen, in fact, is built up
at the expense of foods chemically more complex.
It is, on the contrary, a clearly synthetic pheno-
menon, certainly of chemical complexity, since it ends
in building up the active protoplasm which is, in some
measure, of the highest scale of complexity. Its for-
mation at the expense of the simplest alimentary
materials requires, therefore, an appreciable quantity
of energy.

The assimilation which organizes the active proto-
plasm therefore requires energy for its realization.
Now, at the moment of functional activity, and by a
necessary consequence thereof, the chemical destruc-

^ The reason is to be found in the large number of indeter-
minates in the problem we hj^ve to solve. It will be sufficient
to enumerate them : the two substances which exist in the
anatomical element, protoplasm and reserve -stufif, to which
are attributed contrary roles ; the two conditions attributable
to the protoplasm, of manifested or latent activity ; the faculty
possessed by both of being prolonged for an indeterminate
period, and of encroaching each on its protagonist when its
existence is at stake. Here are more elements than are neces-
sary to explain the positive or negative results of all the
experiments in the world.

112 LIFE AND DEATH.

tion or simplification of the substance of reserve takes
place. Here is something that meets the case, and
we may note the coincid-ence. It does not mean that
the disposable energy is really used to increase the
protoplasm, nor that the protoplasm itself is thereby
increased. It merely signifies that the wherewithal
exists to provide for that increase if it takes place.

It is therefore possible that the active protoplasm
follows the law of functional assimilation ; but it is
certain that the reserve-stuff follows the law laid down
by Claude Bernard.

All these considerations definitely result in the
confirmation of this second law of general physiology,
according to which all vital energies are borrowed
from the potential chemical energy of the reserve-stuff
of alimentary origin.

§ 4. The Third Law of Biological Energetics.

The third law of biological energetics is also drawn
from experiment. It relates no longer to the point of
departure of the cycle of animal energy, but to its
final position. TJie energetic transformations of tJie
animal e?id in thermal energy.

This is the most novel part of the theory, and, if we
may say so, that least understood by physiologists
themselves. The energy resulting from the chemical
potential of food, having passed through the organism
(or simply through the organ which we are considering
in action), and having given rise to phenomenal ap-
pearances more or less diversified, more or less dim or
clear, obscure or obvious, which are the characteristic
or still irreducible manifestations of vitality, finally

ENERGY IN BIOLOGY. II3

returns to the physical world. This return takes
place (with certain exceptions which will be presently
indicated) under the ultimate form of thermal energy.
This we are taught by experiment. The phenomena
of functional activity are exothermal.

Real vital phenomena thus lie between the chemical
energy which gives rise to them, and the thermal
phenomena to which they in their turn give rise. The
place of the vital fact in the cycle of universal energy
is therefore completely determined. This conclusion
is of the utmost importance to biology. It may be
expressed in a concise formula which sums up in a
few words all that natural philosophy can teach as to
energetics applied to living beings. " Vital energy is
a transformation of chemical energy into thermal
energy."

Exceptio7is. — There are some exceptions to the
rigour of this statement, but they arc not many in
number. We must first of all remark that it applies
to animal life alone.

In the case of vegetables, looked at as a whole, the
law must be modified. Their vital energy has another
origin, and another final form. Instead of being the
destroyers of chemical potential energy, they are its
creators. They build up by means of the inert and
simple materials afforded them by the atmosphere
and the soil, the immediate principles by which their
cells are filled. Their vital functional activity forms by
synthesis of the reserves, carbo-hydrates (sugars and
starches), fats, albuminoid nitrogenous materials — that
is to say, the same three principal categories of foods
as those used by animals.

And to return to the latter, it should be observed
that thermal energy is not the only final form of vital

114 LIFE AND DEATH.

energy, as this dogmatic statement would have it
supposed. It is only the principle of the final forms.
The cycle of energy occasionally terminates in
mechanical energy (phenomena of motion) and in
a less degree in other energies ; such as, for example,
the electrical energy produced by the functional activity
of the nerves and muscles in all animals, or in the
functional activity of special organs in rays, torpedo-
fish, and the malapterurus electricus, or finally, in the
photic energy of phosphorescent animals. But these
are secondary facts.

Heat is an Excretuni. — The third principle of bio-
logical energetics may be therefore thus enunciated : —
Vital energy in its final form becomes thermal energy.
This principle teaches us that if chemical energy is
the primitive generating form of vital energies,
thermal energy is the form of waste, of emunctory,
the degraded form as the physicists would say. Heat
is in the dynamical order an excretion of animal
life, as urea, carbonic acid and water, are excreta in
the substantial order. By a false interpretation of
the principle of the mechanical equivalence of heat, or
through ignorance of Carnot's principle, certain
physiologists have fallen into error when they still
speak of the transformation of heat into motion or into
into electricity in the animal organism. Heat is trans-
formed into nothing in the animal organism. It is dis-
sipated. Its utility arises not from its energetic value,
but from the part it plays as a primer in the chemical
reactions, as has been explained with reference to the
general characteristics of chemical energy.

The Effect of Energetics on our Knowledge of the
Relations of the Universe. — The consequences of these
principles of energetic physiology, which give us so

ENERGY IN BIOLOGY. II5

much and which are so clear, are of the greatest
importance from the practical as well as from the
theoretical point of view.

In the first place, they show us the position and the
rank of the phenomena of life in the universe as a
whole. They throw fresh light on the noble harmony
of the animal and vegetable kingdoms which Priestley,
Ingenhousz, Senebier, and the chemical school of the
beginning of the nineteenth century discovered, and
which was expounded by Dumas with incomparable
lucidity and brilliance. Energetics is expressed in a
line. "The animal world expends the energy ac-
cumulated by the vegetable world," It extends these
views beyond the living kingdoms. It shows how the
vegetable world itself draws its activity from the
energy radiated by the sun, and how animals restore
it again, in dissipated heat, to the cosmic medium.
It extends the harmony of the two kingdoms to the
whole of nature. The new science makes of the
whole uniyerse one connected system.

From a more limited point of view, and so that we
may not restrict ourselves to a consideration of the
domain of animal physiology, the laws of energetics
sum up and explain a multitude of facts and of
experimental laws — for example, the law of the inter-
mittence of physiological activity, the facts of fatigue,
the role and the general principles of alimentation,
and the conditions of muscular contraction.

CHAPTER III.

ALIMENTARY ENERGETICS.

Various Problems of Alimentation. § i. Food the source of
Energy and Matter. The two forms of Energy afforded by
Food — Vital Energy, Thermal Energy. Food the source
of Heat. The role of Heat. — § 2. Measure of the output of
Energy— hy the Calometric Method— by the Chemical
Method. — § 3, The regular type of Food, Biothermogenic,
and the irregular type, Thermogenic. — § 4. Food considered
as the source of Heat. The Law of Surfaces. The limits
of Isodynamics.— § 5, Plastic role of Food. Preponderance
of Nitrogenous Foods,

Among the problems on which energetics has
thrown a vivid h'ght we have mentioned alimentation,
muscular contraction, and, more general still, the
intermittence of vital functional activity. We shall
begin with the study of alimentation.

The Different Problems of Alimentation. — What is a
food? In what does alimentation consist? The
dictionary of the Academic will give us our first
answer. It tells us that the word food is applied to
"every kind of matter, whatever may be its nature,
which habitually serves or may serve for nutrition."
This is very well put, but here again we must know
what nutrition is, and that is not a simple matter; in
fact, it practically means whatever is usually placed
on the table in a civilized and polished society. But

116

ALIMENTARY ENERGETICS. II7

it is just the profound reasons for this traditional
practice that we are trying to discover.

The problem of alimentation may be looked at in a
thousand ways. It is culinary, no doubt, and gas-
tronomic ; but it is also economical and social,
agricultural, fiscal, hygienic, medical, and even moral.
But first and foremost, it is physiological. It com-
prises and assumes the knowledge of the general
composition of foods, of their transformations in the
digestive apparatus, and their comparative utility in
the maintenance and the sound functional activity
of the organism. To this first group of subjects for
our discussion are attached others relating to the
effects of inanition, of insufficient alimentation, and of
over-feeding. And in order to throw light on all
these aspects of the problem of alimentation, we have
to lay bare the most intimate and delicate reactions by
which the organism is maintained and recruited, and,
in the words of a celebrated physiologist, " to pene-
trate into the kitchen of vital phenomena." And here
neither Apicius, nor Brillat-Savarin, nor Berchoux,
nor the moralists, nor the economists are of any use
to us as guides. We must appeal to the scientists,
who, following the example of Lavoisier, Berzelius,
Regnault, and Liebig, have applied to the study of
living beings the resources of general science, and
have thus founded chemical biology.

This branch of science developed considerably in
the second half of the nineteenth century. It has now
its methods, its technique, its chairs at the universities,
its laboratories, and its literature. It has particularly
applied itself to the study of the " material changes"
or the Metabolism of living beings, and with that
object in view it has done two things In the first

Il8 LIFE AND DEATH.

place, it has determined the composition of the
constituent materials of the organism ; then analyzing
qualitatively and quantitatively all that penetrates into
that organism' in a given time — that is to say, all the
alimentary or respiratory ingesta, and all that issues
from the organism, i.e., all the excreta, all the egesta,
— it has drawn up mitritive balance sheets, corre-
sponding to the various conditions of life, whether
naturally or artificially created. And thus we can
determine the alimentary regimes which give too
much, and which give too little, and which finally
restore equilibrium.

We do not propose to give a detailed account of
this scientific movement. This may be done in mono-
graphs. All we wish to indicate here is the most
general result of these laborious researches — that is
to say, the laws and the doctrines which are derived
from them, and the theories to which they have given
birth. It is by this alone that they are brought into
relation with general science, and may therefore
interest the reader. The facts of detail are never
lacking to the historian ; it is more profitable to show
the movement of ideas. The theories of alimentation
bring into conflict very different conceptions of
the vital functional activity. And here we find a
confused medley of opinions on which it is not without
interest to endeavour to throw some light.

§ I. Food, a Source of Energy and Matter.

Definitions of Food. — Before the introduction into
physiology of the notion of energy, no one had
succeeded in giving an exact idea and a precise
definition of food and alimentation. Every physio-

ALIMENTARY ENERGETICS. IIQ

legist and medical man who attempted it had failed,
and this for various reasons.

The general cause of this failure was that most de-
finitions, popular or technical, interposed the condition
that the food must be introduced into the digestive
apparatus. " It is," said they, " a substance which
when introduced into the digestive tube undergoes,
etc., etc." But plants draw food from the soil, and
they possess no digestive apparatus; many animals
have no intestinal tube; and in the case of certain
rotifera, the females possess a digestive apparatus,
while the males have none. Nevertheless all animals
feed.

On the other hand, there are other substances than
those which use the digestive tract for the purpose of
entering the organism, and which are eminently useful
or necessary to the maintenance of life. In par-
ticular we may mention oxygen.

The distinctive feature of food is its utility — when
conveniently introduced or employed — to the living
being. Claude Bernard's definition is this: — A sub-
stance taken in the external medium "necessary for the
maintenance of the phenomena of the healthy organism
and for the reparation of the losses it constantly
suffers." " A substance which supplies an element
necessary for the constitution of the organism, or
which diminishes its disintegration^^ (stored-up food);
this is the definition of C. Voit, the German physio-
logist. M. Duclaux says, in his turn, but in far too
general terms, that it is a substance which contributes
to assure the sound functional activity of any of the
organs of the living being. None of these ways of
describing food gives a complete idea.

Food, the Source of Energy and Matter. — The inter-

9

120 LIFE AND DEATH.

vention of the notion of energy enables us more
completely to understand the true nature of food.
We must, in fact, have recourse to the energetic con-
ception if we desire to take into account all that the
organism requires from food. It not only requires
matter, but also, and most important of all, energy.

Investigators so far concentrated their thoughts ex-
clusively on the necessity of a supply of matter — that
is to say, they only looked upon one side of the
problem. The living body presents, at each of its
points, an uninterrupted series of disintegrations and
reconstitutions, the materials being supplied from
without by alimentation, and rejected by excretion.
Cuvier gave to this unceasing circulation of ambient
matter throughout the vital world the name of vital
vortex, and he rightly saw in it the characteristic of
nutrition, and the distinctive feature of life.

This idea of the cycle of matter has been com-
pleted in our own time by that of the cycle of
energy. All the phenomena of the universe, and
therefore those of life, are conceived of as energetic
transformations. We now look at them in their relation-
ship instead of considering them individually as of old.
Each has an antecedent and a consequent unity with
which it is connected in magnitude by the law of
equivalents taught us by contemporary physics. And
thus we may conceive of their succession as the
cycle of a kind of indestructible agent, which changes
only apparently, or assumes another form as it passes
from one to the other, but its magnitude remains
unaltered. This is energy. Thus, in the living being
there is not only a circulation of matter, but also a
circulation of energy.

The most general result of research in physiological

ALIMENTARY ENERGETICS. 121

chemistry from the time of Lavoisier down to our own
day has been to teach us that tJic antecedent of the
vital phenofnenon is always a chemical phenomenon.
The vital energies are derived from the potential
chemical energy accumulated in the immediate con-
stituent principles of the organism. In the same way
the consequent phenomenon of the vital phenomenon is in
general a thermal phenomenon. The final form of
vital energy is thermal energy. These three assertions
as to the nature, the origin, and the final form of vital
phenomena constitute the three fundamental prin-
ciples, the three laws, of biological energetics.

Food, a Source of Heat. It is not qua source of heat
that food is the source of vital energy. — The place of
vital energy in the cycle of universal energy is com-
pletely determined. It lies between the chemical
energy which is its generating form and the thermal
energy which is its form of disappearance, of break-
down, the "degraded form," as the physicists say.
Hence we have a result which can be immediately
applied in the theory of food — namely, that heat is in
the dynamical order an excretum of the animal life
rejected by the living being, just as in the substantial
order, urea, carbonic acid and water, are the materials
used up and again rejected by it. We therefore must
not think of the transformation in the animal organ-
ism of heat into vital energy, as certain physiologists
always do. Nor must we think, with Beclard, of its
transformation into muscular movement; or, as others
have maintained, into animal electricity. This is not
only an error of doctrine but an error of fact. It
proceeds from a false interpretation of the principle of
the mechanical equivalent of heat and a misunder-
standing of Carnot's principle. Thermal energy does

122 LIFE AND DEATH.

not repeat the course of the energetic flux in the
animal organism. The heat is not transformed into
anything. It is simply dissipated.

TJie Part played by Animal Heat as a Condition of
Physiological Manifestations. — Does this mean that
heat is useless to life in the very beings in which it is
most abundantly produced — i.e.^ in man and in the.
warm-blooded vertebrates ? So far from this being so,
it is necessary to life. But its utility has a peculiar
character which must neither be misunderstood nor
exaggerated. It is not transformed into chemical
or vital reactions, but merely creates for them a
favourable condition.

According to the first principle of energetics, for
the vital fact to be derived from the thermal fact, the
heat must be preliminarily transformed into chemical
energy, since chemical energy is necessarily an ante-
cedent and generating form of vital energy. Now
this regressive transformation is impossible according
to the current theories of general physics. The part
played by heat in the act of chemical combination is
that of a primer to the reaction. It consists in placing
the reacting bodies, by changing their state or by
modifying their temperature, in the condition in which
they ought to be for the chemical forces to come into
play. For example, in the combination of hydrogen
and oxygen by setting light to an explosive mixture,
heat only acts as a primer to the phenomenon, because
the two gases which are passive at ordinary tempera-
tures, require to be raised to 400° C. before chemical
affinity comes into play. And so it is with the
reactions which go on in the organism. They have
a maximum temperature, and the part played by
animal heat is to furnish them with it.

ALIMENTARY ENERGETICS. 123

It follows that heat intervenes in animal life in two
capacities — first and foremost as excretum, or end of
the vital phenomenon, of physiological work ; and on
the other hand, as a condition or primer o( the chemical
reactions of the organism ; and generally, as a favour-
able condition for the appearance of the physiological
manifestations of living matter. Thus, it is not
dissipated in sheer waste.

I was led to adopt these views some years ago
from certain experiments on the role played in food by
alcohol. I did not then know that they had already
been expressed by one of the masters of contemporary
physiology, M. A. Chauveau, and that they were
related in his mind to a series of conceptions and of
researches of great interest, in the development of
which I have since then taken a share.

Two Forms of Energy supplied to Animals by Food.
— To say that food is simultaneously a supply of
energy and a supply of matter, is really to express in
a single sentence the fundamental conception of
biology, in virtue of which life brings into play no
substratum or characteristic dynamism. According
to this, the living being appears to us as the
seat of an incessant circulation of matter and energy,
starting from the external world and returning
to it. All food is iiothing but this matter and this
energy. All its characteristics, our views as to its
role, its evolution, all the rules of alimentation are
simple consequences of this principle, interpreted by
the light of energetics.

And first of all, let us ask what forms of energy are
afforded by food ? It is easy to see that there are
two — food is essentially a source of chemical energy ;
and secondarily and accessorily, it is a source of heat.

124 LIFE AND DEATH.

Chemical energy is the only energy, according to the
second law of energetics, which may be transformed
into vital energy. It is true at any rate for animals;
for in plants it is otherwise. There the vital cycle has
neither the same point of departure nor the same final
position. The circulation of energy does not take
place in the same manner.

On the other hand, and this we are taught by the
third law, energy brought into play in vital pheno-
mena is finally liberated and restored to the physical
world in the form of heat. We have just said that
this release of heat is employed in raising the tem-
perature of the living being. It is animal heat.

Thus there are two forms of energy supplied by
food, chemical and thermal.

It must be added that these are not the only forms,
but the principal, and by far the most important. It is
not absolutely true that heat is the only outcome of the
vital cycle. It is only so in the subject in repose, con-
tented to live idly without doing external mechanical
work, without lifting a tool or a weight, even that of its
own body. And again, speaking in this way, we neglect
all the movements and all the mechanical work which
is done without exercise of the volition, by the beating
of the heart and of the arteries, the movements of
respiration, and the contractions of the digestive tube.

Mechanical work is, in fact, another possible termi-
nation of the cycle of energy. But there is no
longer anything necessary or inevitable in this, since
motion and the use of force are in a certain measure
subordinated to the capricious volition of the animal. ^

' There is another reason why the role of mechanical energy,
compared with that of thermal energy, is reduced, in the partition
of afferent, alimentary energy — at least, in animals which have not

ALIMENTARY ENERGETICS. 125

At Other times, again, it is an electrical phenomenon
which terminates the vital cycle, and it is, in fact, in
this way that things happen in the functional activity
of the nerves and muscles in all animals, and in the
functional activity of the electrical organ in fish,
such as the ray and the torpedo. Finally, the ter-
mination may be a photic phenomenon, and this i^
what happens in phosphorescent animals.

It is idle to diminish the power of these principles
by proceeding to enumerate the whole of the ex-
ceptions to their validity. We know perfectly well
that there are no absolute principles in nature. Let
us say, then, that the energy which temporarily
animates the living being is furnished to it by the
external world under the exclusive form of potential
chemical energy; but that, if there is only one door of
entry, there are two exits. It may return to the ex-
ternal world in the principal form of thermal energy
and in the accessory form of mechanical energy.

§ 2. Measurement of the Supply of
Alimentary Energy.

Calorimetric Method. — From what has preceded it
is clear that if the energetic flux which circulates
through the animal emerges, iii toto, in the state of
heat, the measurement of this heat becomes the

to do excessive work. The unit of heat, the Calorie, is equivalent
to 425 units of work — i.e.^ to 425 kilogrammetres. In the animal
at rest, the number of kilogrammetres representing the different
quantities of work done is small, the number of corresponding
Calories is 425 times smaller. It becomes almost negligeable in
comparison with the considerable number of Calories dissipated
in the form of heat.

126 LIFE AND DEATH.

measurement of the vital energy itself, for the origin
of which we must go back to the food. If the flux is
divided into two currents, mechanical and thermal,
they must both be measured and the sum of their
values taken. If the animal does not produce me-
chanical work, and all ends in heat, we have only to
capture, by means of a calorimeter, this energetic flux
as it emerges, and thus measure in magnitude and
numerically the energy in motion in the living being.
Physiologists use for this purpose various types of
apparatus. Lavoisier and Laplace used an ice calori-
meter— that is to say, a block of ice in which they
shut up a small animal, such as a guinea-pig; they
then measured its thermal production by the quantity
of ice it caused to melt. In one of their experiments,
for instance, they found that a guinea-pig had melted
341 grammes of ice in the space of ten hours, and had
therefore set free 27 Calories.

But since those days more perfect instruments have
been invented. M. d'Arsonval employed an air calori-
meter, which is nothing but a differential thermometer
very ingeniously arranged, and giving an automatic
record. Messrs. Rosenthal, Richet, Hirn and Kauf-
mann, and Lefevre have used more or less simplified
or complicated air calorimeters. Others, following
the example of Dulong and Despretz, have used
calorimeters of air and mercury, or with Liebermester,
Winternitz, and J. Lefevre (of Havre), have had
recourse to baths. Here, then, there is a considerable
movement of research which has led to the discovery
of very interesting facts.

Measurement of the Supply of Alimentary Energy
by the Chemical Method. — We may again reach our
result in another way. Instead of surprising the cur-

ALIMENTARY ENERGETICS. I27

rent of energy as it emerges and in the form of
heat, we may try and capture it at its entry in the
form of potential chemical energy.

The evaluation of potential chemical energy may
be effected with the same unit of measurement as the
preceding — that is to say, the Calorie. If we consider
man and mammals, for example, we know that there
is only apparently an infinite variety in their foods.
We may say that they feed on only three substances.
It is a very remarkable fact that all the complexity
and multiplicity of foods, fruits, grains, leaves, animal
tissues, and vegetable products of which use is made,
reduce to so great a simplicity and uniformity, that all
these substances are of three types only: albuminoids,
such as albumen or white of egg — foods of animal
origin or varieties of albumen; carbo-hydrates, which
are more or less disguised varieties of sugar; and
finally, fats.

Here, then, from the chemical point of view, leaving
out certain mineral substances, are the principal
categories of alimentary substances. Here, with the
oxygen that is brought in by respiration, is every-
thing that penetrates thq organism.

And now, what comes out of the organism ? Three
things only, water, carbonic acid, and urea. But the
former are the products of the combustion of the
latter. If we consider an adult organism in perfect
equilibrium, which varies throughout the experiment
neither in weight nor in composition, we may say that
the receipts balance the expenditure. Albumen, sugar,
fat, plus the oxygen brought in, balance quantitatively
the water, carbonic acid, and urea expelled. Things
happen, in fact, as if the foods of the three categories
were burned up more or less completely by the oxygen.

128 LIFE AND DEATH.

It is this combustion that wc have known since the
days of Lavoisier to be the source of animal heat.
We can easily determine the quantity of heat left by
albumen passing into the state of urea, and by the
starch, the sugars, and the fats reduced to the state of
water and carbonic acid. This quantity of heat does
not depend on the variety of the unknown inter-
mediary products which have been formed in the
organism. Berthelot has shown that this quantity of
heat which measures the chemical energy liberated by
these substances is identical with the quantity ob-
tained by burning the sugar and the fats in a chemical
apparatus, in a calorimetric bomb, until we get carbonic
acid and water, and by burning albumen till we get
urea. This result is a consequence of Berthelot's
principle of initial and final states. The liberated
heat only depends on the initial and final states, and
not on the intermediary states. The heat left in the
economy by the food being the same as that left in
the calorimetric bomb, it is easy for the chemist to
determine it. It has thus been discovered that one
gramme of albumen produces 4.8 Calories, one gramme
of sugar 4.2 Calories, and one gramme of fat 9.4
Calories. We thus gather what a given ration — a mix-
ture in certain proportions of these different kinds of
foods — supplies to the organism and what energy
it gives it, measured in Calories.

The calculation may be carried out to a high degree
of accuracy if, instead of confining ourselves to the
broad features of the problem, we enter into rigorous
detail. It is only, in fact, approximately that we have
reduced all foods to albumen, sugar, and fat, and all
excreta to water, carbonic acid, and urea.

The reality is a little more complicated. There

ALIMENTARY ENERGETICS. 129

are varieties of albumen, carbo-hydrates, and fatty
bodies, the heats of combustion of which in the
organism oscillate in the neighbourhood of the num-
bers 4.8, 4.2, and 9.4. Each of these bodies has been
individually examined, and numerical tables have
been drawn up by Berthelot, Rubner, Stohmann, Van
Noorden, etc. The tables exhibit the thermal value
or energetic value of very different kinds of foods.

In our climate, the adult average man, doing no
laborious work, daily consumes a maintenance ration
composed, as a rule, of 100 grammes of albuminoids,
49 grammes of fats, and 403 grammes of carbo-
hydrates. This ration has an energetic value of 2,600
Calories.

It is therefore, thanks to the victories won in the
field of thermo-chemistry, and to the principles laid
down since 1864 by M. Berthelot, that this second
method of attack on nutritive dynamism has been
rendered possible. Physiologists, by the aid of these
methods, have drawn up balance-sheets of energy for
living beings just as they had previously established
balance-sheets of matter.

Now, it is precisely researches of this kind that we
have indicated here as a consequence of biological
energetics, which in reality have helped to build up
that principle. These researches have shown us that,
in conformity with the principles of thermodynamics,
there was not, in fact, in the organism, any trans-
formation of heat into mechanical work, as the
physiologists for a short time supposed, on the
authority of Berthelot. With the help of our theory
this mistake is no longer possible. The doctrine of
energetics shows us in fact the current of energy
dividing itself, as it issues from the living being, into

130 LIFE AND DEATH.

two divergent branches, the one thermal and the
other mechanical, external the one to the other
although both issuing from the same common trunk,
and having between them no relation but this, that
the sum of their discharges represents the total of the
energy in motion. Let us now translate these very
simple notions into the more or less barbarous jargon
in use in physiology. We shall be convinced as we
go on of the truth of the saying of Buffon, that " the
language of science is more difficult to learn than the
science itself" We shall say, then, thfft chemical
energy, that the unit of weight of the food which may
be placed in the organism, constitutes the alimentary
potential, the energetic value of this substance, its
dynainogenic power. It is measured in units of heat,
in Calories, which the substance may leave in the
organism. The evaluation is made according to the
principles of thermo-chemistry, by means of the
numerical tables of Berthelot, Rubner, and Stohmann.
The same number also expresses the thermogenic
power, virtual or theoretical, of the alimentary sub-
stance. This energy being destined to be transformed
into vital energies (Chauveau's physiological work,
physiological energy), the dynamogenic or thermogenic
value of the food is at the same time its biogenetic
value. Two weights of different foods which supply
the organism with the same number of Calories, — i.e.
for which these numerical values are the same, — will be
called isodynamic or isodynamogenic, isobiogenetic, iso-
energetic weights. They will be equivalent from the
point of view of their alimentary value. And finally,
if, as is usually the case, the cycle of energy ends in
the production of heat, the food which has been
utilized for this purpose has a real thermogenic value,

ALIMENTARY ENERGETICS. I31

identical with its theoretical thermogenic value. In
this case it might be determined experimentally by
direct calorimetry, measuring the heat produced by
the animal supposed absolutely unchanged and iden-
tical before and after the consumption of the food.

§ 3. Different Types of Foods. The Regular,

BlOTHERMOGENIC TYPE AND THE IRREGULAR,

Thermogenic Type.

Food is a source of thermal energy for the organ-
ism because it is decomposed within it, and undergoes
within it a chemical degradation. Physiological
chemistry tells us that whatever be the manner in
which it is broken up, it always results in the same
body and always sets free the same quantity of heat.
But if the point of departure and the point of arrival
are the same, it is possible that the path pursued is
not constantly identical. For ex.ample, one gramme
of fat will always give the same quantity of heat,
9.4 Calories, and will always come to its final state
of carbonic acid and water ; but from the fat to
the mixture of carbonic acid gas and water there
are many different intermediaries. In a word wc
get the conception of varied cycles of alimentary
evolutions.

From the point of view of the heat produced it has
just been said that these cycles are equivalent. But
are they equivalent from the vital point of view?
This is an essential question.

Let us imagine the most ordinary alternative.
Food passes from the natural to the final state after
being incorporated with the elements of the tissues.

132 LIFE AND DEATH.

and after having taken part in the vital operations.
The chemical potential only passes into thermal
energy after having passed through a certain inter-
mediary phase of vital energy. This is the normal
case, tJie regular type of alimentary evolution. It may
be said in this case that the food has fulfilled the
whole of its function, it has served for the vital
functional activity before producing heat. It has
been biothermogenic.

The irregular or pure thermogenic type. — And now
let us conceive of the most simple irregular or
aberrant type. Food passes from the initial to the
final state without incorporation in the living cells of
the organism, and without taking part in the vital
functional activity. It remains confined in the blood
and the circulating liquids, but it undergoes in the
end, however, the same molecular disintegration as
before, and sets free the same quantity of heat.
Its chemical energy changes at once into thermal
energy. Food is a pure thermogen. It has fulfilled
only one part of its work. It has been of slight
vital utility.

Does this ever occur in reality? Are there foods
which would be only pure thermogens — that is to
say, which would not in reality be incorporated with
the living anatomical elements, which would form no
part of them either in a state of provisory constituents
of the living protoplasm, or in the state of reserve-
stuff; which would remain in the internal medium, in
the blood and the lymph, and would there undergo
their chemical evolution? Or again, if the whole of
the food does not escape assimilation, would it be
possible for part to escape it ? Would it be possible
for one part of the same alimentary substance to be

ALIMENTARY ENERGETICS. 133

incorporated, and for the rest to be kept in the blood
or the lymph, in the circulating liquids ad liniina
corporis, so to speak ? In other words, can the same
food be according to circumstances a biotJiermogen or
a pure thermogen ? Some physiologists — Fick of
Wurzburg, for instance — have claimed that this is
really the case for most nitrogenous elements, carbo-
hydrates, and fats; all would be capable of evolving
according to the two types. On the other hand, Zuntz
and von Mering have absolutely denied the existence
of the aberrant or pure thermogenic type. No sub-
stances would be directly decomposed in the organic
liquids apart from the functional intervention of the
histological elements. Finally, other authors teach
that there is a small number of alimentary substances
which thus undergoes direct combustion, and among
them is alcohol.

Liebig's Superfluous Consumption. — Liebig's theory
of superfluous consumption and Volt's theory of the
circulating albumen assert that the proteid foods
undergo partial direct combustion in the blood vessels.
The organism only incorporates what is necessary
for physiological requirements. As for the surplus
of the food that is offered it, it accepts it, and, so
to speak, squanders it ; it burns it directly ; and
we have a "sumptuary" consumption, consumption
de luxe.

In this connection arose a celebrated discussion
. which still divides physiologists. If we disen-
{;age the essential body of the discussion from all
that envelops it, we see that it is fundamentally a
question of deciding whether a food always follows the
same evolution whatever the circumstances may be,
and particularly when it is introduced in great excess.

134 LIFE AND DEATH.

Liebig thought that the superabundant part, escaping
the ordinary process, was destroyed by direct com-
bustion. He affirmed, for instance, that nitrogenous
substances in excess were directly burned in the blood
instead of passing through their usual cycle of vital
operations. We might express the same idea by
saying that they then undergo an accelerated
evolution. Instead of passing through the blood in
the anatomical element, to return in the dismem-
bered form from the anatomical element to the blood,
their breaking up takes place in the blood itself.
They save a displacement, and therefore in reality
remain external to the construction of the living
edifice. Their energy, crossing the intermediary vital
stage, passes with a leap from the chemical to the
thermal form. Liebig's doctrine reduced to this
fundamental idea deserved to survive, but mistakes
in minor details involved its ruin.

VotYs Circulating Albumen. — A few years later
C. Voit, a celebrated physiological chemist of Munich,
revived it in a more extravagant form. He held
that almost the whole of the albuminoid element
is burned directly in the blood. He interpreted
certain experiments on the utilization of nitro-
genous foods by imagining that these substances
when introduced into the blood were divided as a
result of digestion into two parts: the one very small,
which was incorporated with the living elements, and
passed into the stage oi organized albumen, the other,
corresponding to the greater part of the alimentary
albumen, remained mingled with the blood and
lymph, and was subjected in this medium to direct
combustion. This was circulating albumen. In this
theory the tissues are almost stable ; the organic

ALIMENTARY ENERGETICS. 135

liquids alone are subjected to oxydizing transforma-
tions, to nutritive metabolism. The accelerated
evolution, which Liebig considered as an exceptional
case, was to C. Voit the rule.

Current Ideas as to the Role of Foods. — The ideas
of to-day are not those of Voit; but they do not,
however, differ from them essentially. We no longer
admit that the greater part of the ingested and
digested albumen remains confined in the circulating
medium external to the anatomical elements. It is
held, with Pflliger and the school of Bonn, that it
penetrates the anatomical element and is incorpor-
ated in it ; but in agreement with Voit it is believed
that a very small part is assimilated to the really
living matter, to the protoplasm properly so called ;
the greater part is deposited in the cellular element
as reserve-stuff. The material, properly so called, of
the living machine does not undergo destruction and
reparation as extensively as our predecessors supposed.
There is no need for great reparation. On the con-
trary, the physiological activity consumes to a great
extent the reserve-stuff. And the greater part of
the food, after having undergone suitable elabora-
tion, serves to replace the reserve-stuff destroyed
in each anatomical element by the vital functional
activity.

Experimental Facts. — Among the facts which
brought physiologists of the school of Voit to believe
that most foods do not get beyond the internal
medium, there is one which may well be mentioned
here. It has been observed that the consumption of
oxygen in respiration increases notably (about a fifth
of its value) immediately after a meal. What does
this mean ? The interval is too short for the digested

lo

136 LIFE AND DEATH.

alimentary substances to have been elaborated and
incorporated in the living cells. It is supposed that
an appreciable time is required for this complete
assimilation. The products of alimentary digestion
are therefore in all probability still in the blood, and
in the interstitial liquids in communication with it.
The increase of oxygen consumed would show that a
considerable portion of these nutritive substances
absorbed and passed into the blood would be oxy-
dized and then and there destroyed. But this
interpretation, however probable it may be, does not
really fit in with the facts in such a way that we may
consider it as proved. Certain experiments by Zuntz
and Mering are opposed to the idea that combustion
in the blood is easy. These physiologists injected
certain oxydizable substances into the vessels without
being able to detect any instantaneous oxidation.
It is only fair to add that against these fruitless
attempts other more fortunate experiments may be
quoted.

Category of Purely Thermogenic Foods, zvith Ac-
celerated Evolution. Alcohol. Acids of Fruits. —
The accelerated evolution of foods — an evolution
which takes place in the blood, that is to say outside
the really living elements — remains, therefore, very
uncertain as far as ordinary food is concerned. It
has been thought that it was a little less uncertain
as far as the special category of alcohol, acids of
fruits, and glycerine is concerned.

Some authors consider these bodies as pure
thermogens. When alcohol is ingested in moder-
ate doses, they say that about a tenth of the
quantity absorbed becomes fixed in the living tissues;
the rest is " circulating alcohol." It is oxidized

ALIMENTARY ENERGETICS. 137

directly in the blood and in the lymph, without inter-
vening in the vital functions other than by the heat
it produces. From the point of view of the energetic
theory these are not real foods, because their potential
energy is not transformed into any kind of vital
energy, but passes at once to the thermal form. On
the other hand, other physiologists look upon alcohol
as really a food. According to them everything is
called a food which is transformed in the organism
with the production of heat ; and they measure the
nutritive value of a substance by the number of
Calories it can give up to the organism. So that
alcohol would be a better food than carbohydrated
and nitrogenous substances. A definite quantity of
alcohol, a gramme for instance, is equivalent from
the thermal point of view to 1.66 grammes of sugar,
1.44 of albumen, or 0.73 of fat. These quantities
would be isodynamic.

Experiment has not entirely decided for or against
this theory. However, the first tests have not been
very favourable to it. The researches of C. von
Noorden and his pupils, Stammreich and Miura, have
clearly and directly established that alcohol cannot
be substituted in a maintenance ration for an exactly
isodynamic quantity of carbohydrates. If the sub-
stitution is effected, a ration only just capable of
maintaining the organism in equilibrium becomes in-
sufiicient. The animal decreases in weight. It loses
more nitrogenous matter than it can recover from
its diet, and this situation cannot be sustained for
long. On the other hand, the celebrated researches
of the American physiologist, Atwater, would plead,
on the contrary, in favour of almost isodynamic sub-
stitution. Finally, Duclaux has shown that alcohol

138 LIFE AND DEATH.

is a real food, biothermogenic for certain vegetable
organisms. But urea is also a food for micrococcus
urecs. It does not follow that it is a food for mann-
mals. We have not reached the solution yet — adJiuc
sub judice.

Conclusion : The Energetic Character oj Food. — To
sum up we have confined ourselves, in what has been
said, to the consideration of a single character of
food, and really the most essential, its energetic
character. Food must furnish energy to the organism,
and for that purpose it is decomposed and broken up
within it, and issues from it simplified. It is thus,
for instance, that the fats, which from the chemical
point of view are complicated molecular edifices,
escape in the form of carbonic acid and water. And
so it is with carbo-hydrates, starchy and sugary
substances. This is because these compounds
descend to a lower degree of complexity during their
passage through the organism, and by this drop, as it
were, they get rid of the chemical energy which they
contained in the potential state. Thermo-chemistry
enables us to deduce from the comparison of the
initial and final states the value of the energy
absorbed by the living being. This energetic, dynamo-
genie or thermogenic value, thus gives a measure of
the alimentary capacity of the substance. A gramme
of fat, for instance, gives to the organism a quantity
of energy equivalent to 9.4 Calories ; the thermo-
genic value of the albumenoids is 4.8 Calories.
The thermogenic or thermal value of carbohydrates
is less than 4.7 calories. This being so, we under-
stand why the animal is nourished by foods which
are products very high in the scale of chemical
complexity.

alimentary energetics. 139

§ 4. Food considered exclusively as
Source of Heat.

We have seen that food is, in the first place, a •
s,ource oi chejnical energy ; and, in the second place,
a source o{ vital energy — finally, and consequently, a
source of thermal energy. It is this last point of
view which has exclusively struck the attention of
certain physiologists, and hence has arisen a peculiar
manner of conceiving the role of food. It consists in
looking on food as a source of thermal energy.

This conception is easily applied to warm-blooded
animals, but to them exclusively — and this is where
it first fails. The animal is warmer than the environ-
ment in general. It is constantly giving out heat to
it. To repair this loss of heat it takes in food in
exact proportion to the loss it sustains. When it is a
question of cold-blooded vertebrates, which live in
water and in most cases have an internal tem-
perature which is not distinguishable from that of
the environment, we see less clearly the thermal role
of food. It seems then that the production of heat
is an episodic phenomenon, not existing for itself.

However that may be, food is in the second place
a source of thermal energy for the organism. Can it
be said, inversely, that every substance which we in-
troduce into the economy, and which is there broken
up and gives off heat, is a food ? This is a moot
point. We dealt just now with purely thermogenic
foods. However, most physiologists are inclined to
give a positive answer. In their eyes the idea of food
cannot be considered apart from the fact of the pro-
duction of heat. They take the effect for the

140 LIFE AND DEATH.

cause. To these physiologists everything ingested is
called food, if it gives off heat within the body.

To be heated by food is, indeed, an imperious
necessity for the higher animals. If this need be not
satisfied the functional activities become enervated ;
the animal falls into a state of torpor ; and if it is
capable of attenuated, of more or less latent, life it
sleeps in a state of hibernation ; but if it is not
capable of this, it dies. The warm-blooded animal
with a fixed temperature is so organized that this
constancy of temperature is necessary to the exercise
and to the conservation of life. To maintain this
indispensable temperature there must be a continual
supply of thermal energy. According to this, the
necessity of alimentation is confused with the
necessity of a supply of heat to cover the deficit
which is due to the inevitable cooling of the organism.
This is the point of view taken up by theorists, and
we cannot say that they have no right to do so. We
can only protest against the exaggeration of this
principle, and the subordination of the other roles of
food to this single r6le as a thermogen. It is the
magnitude of the thermal losses which, according to
these physiologists, determines the need for food, and
regulates the total value of the maintenance ration.
From the quantitative view it is approximately true.
From the qualitative point of view it is false.

Such is the theory opposed to the theory ol
chemical and vital energy. It has on its side a large
number of experts, among whom are Rubner, Stoh-
mann, and von Noorden. It has been defended in an
article in the Dictionnaire de PJiysiologie by Ch.
Richet and Lapicque. They hold that thermogenesis
absolutely dominates the play of nutritive exchanges ;

ALIMENTARY ENERGETICS. I4I

and it is the need for the production of heat that
regulates the total demand for Calories which every
organism requires from its ration. It is not because
it produces too much heat that the organism gets rid
of it peripherally : it is rather because it inevitably
disperses it that it is adapted to produce it.

Rubner's Experiments. — This conception of the role
of alimentation is based on two arguments. The first
is furnished by Rubner's last experiment (1893). A
dog in a calorimeter is kept alive for a rather long
period (two to twelve days) ; the quantity of heat
produced in this lapse of time is measured, and it is
compared with the heat afforded by the food. In all
cases the agreement is remarkable. But is it possible
that there should be no such agreement ? Clearly no,
because there is a well-known regulating mechanism
which always exactly proportions the losses and the
gains of heat to the necessity of maintaining the fixed
internal temperature. This first argument is, there-
fore, not conclusive.

The second argument is drawn from what has been
called the iaw of surfaces, clearly perceived by Reg-
nault and Reiset in their celebrated memoir in 1849,
formulated by Rubner in 1884, and beautifully
demonstrated by Ch. Richet. In comparing the
maintenance rations for subjects of very different
weights, placed under very different conditions, it is
found that the food always introduces the same num-
ber of Calories for the same extent of skin — i.e., for
the same cooling surface. The numerical data
collected by E. Voit show that, under identical con-
ditions, warm-blooded animals daily expend the same
quantity of heat per unit of surface — namely, 1.036
Calories per square yard. The average ration intro-

142 LIFE AND DEATH.

duces exactly the amount of food which gives off
sensibly this number of Calories. Now, this is an
interesting fact, but, like the preceding, it has no
demonstrative force.

Objections. T/ie Limits of Isodynamism. — On the
contrary, there are serious objections. The thermal
value of the nutritive principles only represents one
feature of their physiological role. In fact, animals
and man are capable of extracting the same profit
and the same results from rations in which one of the
foods is replaced by an isodynamic proportion of the
other two — that is to say, a proportion developing the
same quantity of heat. But this substitution has very
narrow limits. Isodynamism — that is to say, the
faculty that food has of supplying /r^ rata its thermal
values — is limited all round by exceptions. In the
first place, there are a few nitrogenous foods that no
other nutritive principle can supply ; and besides, be-
yond this minimum, when the supply takes place, it is
not perfect. Lying between the albuminoids and the
carbohydrates relatively to the fats, it is not between
these two categories relatively to nitrogenous sub-
stances. If the thermal power of food were the only
thing that had to be considered in it, the isodynamic
supply would not fail in a whole category of principles
such as alcohol, glycerine, and the fatty acids. Finally,
if the thermal power of a food is the sole measure of
its physiological utility, we are compelled to ask why
a dose of food may not be replaced by a dose of heat.
External warming might take the place of the internal
warming given by food. We might be ambitious
enough to substitute for rations of sugar and fat an
isodynamic quantity of heat-giving coal, and so
nourish the man by suitably warming his room. In

ALIMENTARY ENERGETICS. I43

reality, food has many other offices to fulfil than
that of warming the body and of giving it energy —
that is to say, of providing for the functioual activity
of the living machine. It must also serve to provide
for wear and tear. The organism needs a suitable
quantity of certain fixed principles, organic and
mineral. These substances are evidently intended to
replace those which have been involved in the cycle
of matter, and to reconstitute the organic material.
To these materials we may give the name of histo-
genetic foods (repairing the tissues), or of plastic
foods.

§ 5. The Plastic R6le of Food.

Opinions of the Early PJiysiologists.-^\\. is from this
point of view that the ancients regarded the role of
alimentation. Hippocrates, Aristotle, and Galen
believed in the existence of a unique nutritive sub-
stance, existing in all the infinitely different bodies
that man and the animals utilize for their nourish-
ment. It was Lavoisier who first had the idea of a
dynamogenic or thermal role of foods. Finally, the
general view of these two species of attributes and
their marked distinction is due to J. Liebig, who
called them plastic and dynamogenic foods. In addition
he thought that the same substance should accumulate
the same attributes, and that this was the case with
the albuminoid foods, which were at once plastic and
dynamogenic.

Preponderance of Nitrogenous Foods. — Magendie, in
1836, was the pioneer who introduced in this inter-
minable list of foods the first simple division. He
divided them into proteid substances, still called

144 LIFE AND DEATH.

albuminoids, nitrogenous, quaternary, and ternary
substances. Proteid substances are capable of main-
taining life. Hence the preponderant importance
given by the eminent physiologist to this order of
foods. These results have since been verified. Pfluger,
of Bonn, gave a very convincing proof of this a few
years ago. He fed a dog, made it work, and finally
fattened it, by giving it nothing at all to eat but meat
from which had been extracted, as thoroughly as
possible, every other substance.^ The same experiment
showed that the organism can manufacture fats and
carbo-hydrates at the expense of the nitrogenous food,
when it does not find them ready formed in the ration.
The albumen will suffice for all the needs of energy and
and matter. To sum up, there is no necessary fat, no
carbohydrate is necessary; albuminoids alone are in-
dispensable. Theoretically, the animal and man alike
could maintain life by the exclusive use of proteid
food; but, practically, this is not possible for man,
because of the enormous amount of meat which
would have to be used (3 kilogrammes a day).

Ordinary alimentation comprises a mixture of
three orders of substances, and to this mixture
albumen brings the plastic element materially neces-
sary for the reparation of the organism ; it also is
the source of energy. The two other varieties only
bring energy. In this mixed regimen the quantity
of albumen must never descend below a certain
minimum. The efforts of physiologists of late years
have tended to fix with precision this minimum
ration of albuminoids — or as we may briefly put it,

^ It is not certain, however, that all the precautions taken
have the desired result. You cannot entirely deprive meat of its
carbohydrates.

ALIMENTARY ENERGETICS. I45

of albumen — below which the organism would perish.
Voit had found 118 grammes of albumen necessary
for the average adult man weighing 70 kilos. This
figure is certainly too high. The Japanese doctors,
Mori, TsuboY, and Murato, have shown that a con-
siderable portion of the population of Japan is
content with a diet much poorer in nitrogen, and
suffers no inconvenience. The Abyssinians, according
to Lapicque, ingest, on the average, only Gy
grammes of albumen per day. A Scandinavian physi-
ologist, Siven, experimenting on himself, found that
he could reduce the ration of albumen necessary to
the maintenance and equilibrium of the organism to
the lowest figures which have been yet reached —
namely, from 35 to 46 grammes a day. These
experiments, however, must be confirrhed and inter-
preted. Besides, it is important to point out that the
most advantageous ration of albumen requires to be
a good deal above the strictly sufficient quantity.

It only remains to refer to several other recent
researches. The most important of many are those
published by M. Chauveau, on the reciprocal trans-
formation of the immediate principles in the organism
according to the conditions of its functioning and
the circumstances of its activity. To deal with
these researches with as much detail as they deserve,
wq must study the physiology of muscular contraction
and of movement — that is to say, of muscular
energetics.

BOOK III.

THE CHARACTERS COMMON TO LIVING BEINGS.

Chapter I. Summary: The doctrine of vital unity. — Chapter II.
The morphological unity of living beings. — Chapter III.
The chemical unity of living beings. — Chapter IV. The
mutability of living beings. — Chapter V. The specific
form, its acquisition, and reparation. — Chapter VI. Nutri-
tion.

CHAPTER I.

THE DOCTRINE OF VITAL UNITY.

Phenomena common* to all living beings — Theory of vital
duality — Unity in the formation of immediate principles —
Unity in the digestive acts — The common vital fund.

When we ask the various philosophical schools what
life is, some show us a chemical retort, and others
show us a soul. Whether vitalists or of the mechanical
school, these are the adversaries who since philosophy
began have vainly contested the possession of the
secret of life. We need not concern ourselves with this
eternal quarrel. We need not ask Pythagoras, Plato,
Aristotle, Hippocrates, Paracelsus, Van Helmont,
and Stahl what idea they formed of the vital
principle ; nor need we probe to the depths the
ideas of living nature held by Epicurus, Democritus,

146

THE DOCTRINE OF VITAL UNITY. I47

Boerhaave, Willis, and Lamettrie ; nor need we
apply to the iatromechanicians nor to the chemists.
We may do better than that. We may ask nature
itself.

Phenomena Common to Living Beings. — Nature
shows us an infinite number of beings, animal or
vegetable, described in ordinary language as living
beings. This language implicitly assumes something
common to them all, a universal manner of being
which belongs to them without distinction, without
regard to differences of species, types, or kingdoms.
On the other hand, anatomical analysis teaches us
that animated beings and plants may be divided into
parts ever decreasing in complexity, of which the
last and the simplest is the anatomical element, the
cell, the microscopic organic unit which,-too, is alive.
Common opinion suspects that all these beings,
whether entire as in the case of animal and vege-
table individuals, or fragmentary as in the case of
cellular elements, have the same manner of being,
and present the same body of common characteristics
which rightly gives them this unmistakable title of
living beings. Life then essentially would be this
manner of being, common to animals, vegetables, and
their elements. To seize in isolation these common,
necessary, and permanent features, and then to
synthetize them into a whole, will be the really
scientific method of defining life, and of explaining
its nature.

And here then immediately arises a fundamental
question which gives one pause, a question of fact
which must be solved before we can go further.
Is there really a common manner of being in all
these things ? Are animal life^ vegetable life, and the

148 LIFE AND DEATH.

life of the elements or elementary life, all the same?
Is there a sum total of characteristics which may
define life in general ?

The physiologists, following in the steps of Claude
Bernard, respond in the affirmative. They accept as
valid and convincing the proof given of this vital
community by the illustrious experimentalist. How-
ever, there are some rare exceptions to this universal
assent. In this concert of approval thsre is at least
one discordant voice, that of M. F. Le Dantec.^

^ M. Le Dantec, of whose philosophical and rigorously
systematic mind I have the highest opinion, has laid down a
new conception of life, the essential basis of which is this very
distinction between elementary life and ordinary life; between
the life of the elements or of the beings formed from a single
cell, protophytes and protozoa, and the life of ordinary animals
and plants, which are multicellular complexes, and for that
reason called metazoa and vietaphytes.

Further, in the elementary life peculiar to monocellular
beings (protozoa and cellular elements), M. Le Dantec dis-
tinguishes three manners of being: — The first condition, which
is elementary life manifested in all its perfection, cellular
health; the second condition is deteriorated elementary life,
cellular disease; and the third condition, which is latent life.
I should say at once that in so far as the fundamental dis-
tinction of the phenomena of elementary life and those of the
general life of animals and ordinary plants, metazoa or meta-
phytes, is concerned, we find it neither justified nor useful.
And further, manifested elementary life, as M. Le Dantec
understands it, would only belong to a small number of
elementary beings — for the protozoa, starting with the infusoria,
are not among the number — and to a still smaller number of
anatomical elements, since among the vertebrates we recognize
as almost the only elements satisfying it, the ovule, and perhaps
the leucocyte. Physiologists, therefore, do not agree with
M. Le Dantec as to the utility of adding one condition more to
those we all admit — namely, manifested animal life and latent
life.

THE DOCTRINE OF VITAL UNITY, 149

TJie Doctrine of the Vital Duality of Animals and
Plants. — There are, therefore, biologists who, in the
domain of theory and in virtue of more or less well-
founded conceptions or interpretations, separate
elementary life from other vital forms, and thus break
the bond of vital unity proclaimed by Claude Bernard.
This monistic doctrine at the outset met with other
opponents, and that, too, in the domain of facts.
But it triumphed over them and became established.
We have to deal with scientists like J. B. Dumas and
Boussingault, who drew a dividing line between
animal life and vegetable life.

But let us in a few words recall to the reader this
victorious struggle of the monistic doctrine against
the dualism of the two kingdoms. If we consider an
animal in action, said the champions of vital dualism,
we agree that it feels, moves, breathes, digests, and
finally, that it destroys by a real operation of chemical
analysis the materials afforded to it by its ambient
world. It is in these phenomena that are manifested
its activity, its life. Now, added the dualists, plants
do not feel, do not move, do not breathe, and do not
digest. They build up from immediate principles,
by an operation of chemical synthesis, the materials
they borrow from the soil which bears them, or from
the atmosphere which surrounds them. There is,
therefore, nothing in common between the repre-
sentatives of the two kingdoms if we confine ourselves
to the examination of the actual phenomena which
take place in them. To find a resemblance between
the animal and the vegetable, said the dualists, we
must set aside what they do, for they do different, or
even contrary things. VVe must consider whence
they come and what the}- become. Both originate

150 LIFE AND DEATH.

in organisms similar to themselves. They grow,
evolve, and generate as they themselves weie
generated. In other words, while their acts separate
plants from animals, their mode of origin and
evolution alone bring them together. Such analogies
are of no slight importance ; but they were neutralized
by their dissimilarities, which were exaggerated by
the dualistic school.

It is clear that the word life would lose all actual
significance to those who would reduce it to the
faculty of evolution, and who would separate all its
real manifestations in animated beings and in plants.
If there are two lives, the one animal and the other
vegetable, there are no more ; or, what comes to the
same thing, there is an infinite number of lives which
have nothing in common but the name, or at most,
the possession of some secondary characteristics.
There are as many of them as there are different
beings, for each has its own particular evolution.
Here the specific is the negation of the general and
it destroys it instead of being subordinate to it. The
principle of life becomes for each being something as
individual as its own evolution. And this, if we
think it out, is how the philosophers look at life, and
it is the real reason of their disagreement with the
physiological school.

Proof of the Monistic Theory. — On the other hand,
under the disguise of living forms, the physiologist
recognizes the existence of an identical basis. His
trained ear marks amid the overcharged in-
strumentation of the vital work the recognizable
undertones of a constant theme. It was the work of
Claude Bernard to bring this common basis to
light. He shows that plants live as animals do,

THE DOCTRINE OF VITAL UNITY. I5I

that they breathe, digest, have sensory reactions,
move essentially like animals, destroy and build up
in the same manner the immediate chemical prin-
ciples. For that purpose it was necessary to pass in
review, examining them from their foundation and
distinguishing the essential from the secondary, the
different vital manifestations — digestion, respiration,
sensibility, motility, and nutrition. This is what
Claude Bernard did in his work Siir les PJienomenes
de la vie comnmns mix anhnaux ei aux plantes. We
need only to sketch in broad outline the character-
istic features of his lengthy demonstration.

Unity in the Formation of Immediate Cheinical
Principles. — The first and most important of the
differences pointed out between the lifb of animals
and that of plants was relative to the formation of
immediate principles. On this ground, indeed, vital
dualism raised its fortress. The animal kingdom
was considered in its totality as the parasite of the
vegetable kingdom. To J. B. Dumas, animals,
whatever they may be, make neither fat nor any
elementary organic matter ; they borrow all their
foods, whether they be sugars or starches, fats or
nitrogenous substances, from the vegetable kingdom.
About the year 1843 the researches of the chemists,
and of Payen in particular, succeeded in proving the
presence, almost constant, of fatty matters in vege-
tables ; and, further, these matters existed there in
proportions more than sufficient to explain how
the beast which fed upon them was fattened. The
chemists attributed to nature as much practical sense
as they themselves possessed ; and since the hay and
the grass of the ration brought fat ready made to the
horse, the cow, and the sheep, they declared that the

II

152 LIFE AND DEATH.

animal organism had nothing whatever to do but to
put this food into the tissues, or to arrange for it to
pass into the milk. But nature is not so wise and
economical as was supposed at the Academic des
Sciences, After a memorable debate, in which
Dumas, Boussingault, Payen, Liebig, Persoz, Chossat,
Milne- Edwards, and Flourens took part, and, later on,
Berthelot and Claude Bernard, it was agreed that
the animal does not grow fat from the fatty food
which is supplied it, and that it makes its own fat
just as the vegetable does, but in another manner.
In the same way sugar, the normal constituent sub-
stance necessary for the nutrition of animals and
plants, instead of being a vegetable product passing
by alimentation from the herbivorous animals and
thence to the carnivorous, is manufactured by the
animal itself Generally speaking, immediate prin-
ciples have an equal claim to existence in the two
kingdoms. Both form and destroy the substances
indispensable to life.

Here, then, one of the barriers between animal life
and vegetable life is overthrown and destroyed.

Unity of Digestive Acts in Animals and Plants. —
Similarly, another barrier falls if we show that
digestion, long considered the exclusive function of
animals, and, in particular, of the higher animals, is
in reality universal.

Cuvier pointed out the absence of a digestive
apparatus as a very general and distinctive char-
acteristic of plants. But the absence of a digestive
apparatus does not necessarily imply the absence of
digestion. The essential act of digestion is indepen-
dent of the infinite variety of the organs, just as a
reaction is independent of the form of the vessel in

THE DOCTRINE OF VITAL UNITY. I53

which it takes place. It is, in fact, a chemical
transformation of an alimentary substance. This
transformation may be realized outside the organism,
in vitro, just as it can in the living being without
masticating organs, without an intestinal apparatus,
without glands, in a vessel placed in a stove, simply
by means of a few soluble ferments — pepsine, trypsine,
amylolytic diastases.

All alimentary substances, whether taken from
without or borrowed from the reserves accumulated
in the internal stores of the organism, must undergo
preparation. This preparation is digestion. Diges-
tion is the prologue of nutrition. It is over when the
reparative substance, whether food or reserve-stuff,
is brought into a state enabling it to pass into the
blood, and to be utilized by the organism.

The Identity of Categories of Foods in the Tivo
Kingdoms. — Now the alimentary substances are the
same in the two kingdoms, and so is their digestive
preparation. Alimentary materials are of four
kinds : albuminoid, starchy, fatty, and sugary sub-
stances. The animal takes them from without
(food properly so-called), or from within (reserve-
stuff). Man obtains starch, for instance, from different
farinaceous dishes. It may, however, equally well
be borrowed from the reserve of flour that we carry
within us in our liver, which is a veritable granary,
full of floury substance, glycogen. And so it is with
vegetables. The potato has its store of flour in its
tuber just as the animal has in its liver. The grain
which is about to germinate has it in reserve-stuff in
its cotyledons, or in its albumen. The bud which is
about to develop into a tree or a flower carries it at
its base.

154 LIFE AND DEATH.

The same conclusions are true for another class
of substances, the sugars. They may be a food taken
from without, or a reserve deposited in the tissues.
The animal takes from without, in fruits for instance,
the ordinary sugar which pleases its taste. Beetroot,
when flowering and fructifying, draws this substance
from its roots in which stores have been amassed.
The sugar cane when running to seed takes the
sugar from the stores which it possesses in its cane.
Brewer's yeast, the saccharomyces cerevisice, the agent
of alcoholic fermentation, finds this same substance in
the sugary juices favourable to its development.

In the same way, identically fatty substances,
either in the form of food or of reserve-stuff, serve
for nutrition to animals and vegetables ; and that is
again true of the substances of the fourth class,
albuminoids, identical in the two kingdoms, foods or
reserve-stuff, equally utilizable in both after digestion.

Identity of the Digestive Agents and Mechanisms in
Plants and Animals. — Now, the results of contem-
porary research have been to establish a surprising
resemblance in the modifications experienced by these
foods, or reserve stuffs, in animals and plants; and
even resemblances in the agents which realize them,
and in the mechanisms by which they are performed.
There is a real unity. The flour accumulated in the
tuber of the potato is liquefied and digested on the
appearance of the buds or of the flower, just as the
starch of the liver or the alimentary flour is digested
by the animal. The fatty matter which is stored up
in the oleaginous grain is digested at the moment of
germination, just as the fat during a meal is digested
in the animal's intestine. As the beetroot begins to
run to seed, the root gives up part of its store of

THE DOCTRINE OF VITAL UNITY. 155

sugar, and this reserve stuff is distributed throughout
the stalk after having been digested, exactly as would
have been the case in the digestive canal of man.

Vegetables, then, really digest. The four classes of
substances mentioned above are really digested in
order to pass from their actual form, a form unsuitable
for interstitial exchanges, to another form suitable for
nutrition. As there are four kinds of foods, so there
are four kinds of digestions, four kinds of ferment-
producing agents-^amylolytic,^ proteolytic,^ sacchar-
ine, and lipasic^ diastases, identical in the animal
and the plant. Identity of ferments implies identity
of digestions. Going down to the very basis of
things, the digestive act is nothing but the action of
this ferment. This is the crux of the whole question.
All else is only difference in scene, varying in the
means of execution and in the accessories. The
difference arises from the stage on which it takes
place, but the piece which is being played is the
same, and the actors are the same, and so is the
action of the play.

This identity between animal and vegetable life is
found in the phenomena of respiration and of motility.
The limits of this book do not allow of our entering
into the details of facts. Besides, the facts are well
known, and may be found in any treatise on general
physiology. This science, therefore, enables us to
perceive the imposing unity of life in its essential
manifestations.

^ Amylolj'tic ferments change starch and glycogen {ainyloses)
into sugar. — Tr.

■^ Proteolytic ferments change proteids into peptones and
proteoses. — Tr.

' The enzyme known as lipase splits the fat or oil in germ-
inating seeds into a fatty acid and glycerine. — Tr.

156 LIFE AND DEATH.

The community of the phenomena of vitality in
animals and plants being thus placed beyond a doubt,
we must now discover the reason why. This reason
is to be found in their anatomical and in their
chemical unity. The fundamental phenomena are
common because the composition is common, and
because the universal anatomical basis, the cell,
possesses in all cases a sum total of identical
properties.

If we appeal to physiology for the characteristics
common to living beings, it will generally give us the
following : — A structure, or organization ; a certain
chemical composition which is that of living matter ;
a specific form; an evolution which in the earliest
stage occasions the being to grow and develop until
it is divided, and which in the highest stage includes
one or more evolutive cycles with growth, the adult
stage, senility, and death ; a property of increase or
nutrition, with its consequence — namely, a relation of
material exchanges with the ambient medium ; — and
finally, a property of reproduction. It is important
to pass them rapidly in review.

CHAPTER II.

MORPHOLOGICAL UNITY OF LIVING BEINGS.

§ I. The cellular theory. First period: division of the organism
— ^5 2. Second period: division of the cell — Cytoplasm —
The nucleus — § 3. Physical constitution of living matter —
The micellar theory — § 4. Individuality of complex beings
— The law of the constitution of organisms.'

The first characteristic of the living beings is
orgattisation. By that we mean that they have a
structure; that they are connplex bodies formed of
smaller aliquot parts and grouped according to a
certain disposition. The most simple elementary
being is not yet homogeneous. It is heterogeneous.
It is organized. The least complex protoplasms,
that of bacteria, for example, still possess a
physical structure; Kunstler distinguishes in them
two non-miscible substances, presenting an alveolar
organization. Thus animals and plants present an
organization, and it is sensibly constant from one end
to the other of the scale of beings. There is a
morphological unity.

§ I. The Cellular Theory. First Period :
Division of the Organism into Cells.

Cellular Theory. First Period. — Morphological
unity results from the existence of a universal

157

t

15^ LIFE AND *D'£ATH.

anatomical basis, the ce//. The cellular theory sums
up the teaching of general anatomy or histology.

At the beginning of the nineteenth century anatomy
was following a routine dating from ancient times.
It divided animal and vegetable machines into units
in descending order, first into different forms of
apparatus (circulatory, respiratory, digestive, etc.);
then the apparatus into organs examined one by one,
figuring and describing each of them from every
point of view with scrupulous accuracy and untiring
patience. If we think of the duration of these
researches — the Iliad, as Malgaigne says, already
containing the elements of a very fine regional
anatomy — and especially of the powerful impulse
they received in the seventeenth and eighteenth
centuries, we shall understand the illusion of those
who, in the days of X. Bichat, could fancy that the
task of anatomy was almost ended.

As a matter of fact this task was barely begun, for
nothing was known of the intimate structure of the
organs. X. Bichat accomplished a revolution when
he decomposed the living body into tissues. His
successors, advancing a step in the analysis, dis-
sociated the tissues into elements. These elements,
which one would have thought were infinitely varied,
were reduced in their turn to one common prototype,
the cell.

The living body, disaggregated by the histologist,
resolves under the microscope into a dust, every grain
of which is a cell. A cell is an anatomical element
the constitution of which is the same from one part
to the other of the same being, and from one being to
another; and its dimensions, which are sensibly
constant throughout the whole of the living world.

MORPHOLOGICAL UNITY OF LIVING BEINGS. I59

have an average diameter of several thousandths of
a millimetre — i.e., of several microns. This element,
the cell, is a real organ. It is smaller, no doubt, than
those described by the ancient anatomists, but it is not
less complex. Its complexity is only revealed later.
It is an organic unit. Its form varies from one
element to another. Its substance is a semi-fluid
mass, a mixture of different albuminoids. In the
mean value of its dimensions, so carefully measured —
exceptis exxipiendis — we have a condition the signi-
ficance of which has not yet been discovered, but
which may be of great value in the explanation of its
peculiar activities.

Such is the result to which have converged the re-
searches of the biologists who have examined plants
or the lower animals, as well as of the anatomists who
have been more especially occupied with the verte-
brates and with man. All their researches have
brought them to the same conclusion — the cellular
theory. Either living beings are composed of a single
cell — as is the case with the microscopic animals called
protozoa, and the microscopic vegetables called proto-
phytes — or, they are cellular complexes, metazoa or
inetapJiytes — that is to say, associations of these
microscopic organic units which are called cells.

The Lazu of the Composition of Organisms. — The
law of the composition of organisms was discovered
in 1838 by Schleiden and Schwann. From that time
up to 1875 it may be said that micrographers have
spent their time in examining every organ and every
tissue, muscular, glandular, conjunctive, nervous, etc.,
and in showing that in spite of their varieties of
aspect and form, of the complexity of structures due
to cohesion and fusion, they all resolve into the com-

l6o LIFE AND DEATH.

mon element, the cell. Contemporary anatomists,
Koelliker, Max Schultze, and Ranvier, have thus
established the generality of the cellular constitution,
while zoologists and botanists confirm the same law
for all animals and vegetables, and exhibit them all
as either unicellular or multicellular.

The Cellular Origin of Complex Beings. — At the
same time embryogenic researches showed that all
beings spring from a corpuscle of the same type.
Going back in the history of their development to the
most remote period, we find a cell of very constant
constitution — namely, the ovule. This truth may be
expressed by changing a word in Harvey's celebrated
aphorism — omne vivum ex ovo ; we now say omne
vivuni e cellula. The myriads of differentiated ana-
tomical elements whose association forms complex
beings are the posterity of a cell, of the primordial
ovule, unless they are the posterity of another equiva-
lent cell. The second task of histology in the latter
half of the nineteenth century consisted in following
up the filiation of each anatomical element from the
cell-egg to its state of complete development.

The whole cellular theory is contained in the
two following statements, which establish the mor-
phological unity of living beings : — Everything is a
cell, everything comes from an initial cell; the cell
being defined as a mass of substance, protoplasm or
protoplasms, of an average diameter of a few microns.

§ 2. The Second Period : the Division of
THE Cell.

Second Period: Constitution of the Cell. — This was,
however, only the first phase in the analytical study

MORPHOLOGICAL UNITY OF LIVING BEINGS. l6l

of the living being. A second period began in
1873 with the researches of Strassburger, Biitschh*,
Flemming, Kuppfer, Fromann, Heitzmann, Balbiani,
Guignard, Kunstler, etc. These observers in their
turn submitted this anatomical, this infinitely small
cellular microcosm, to the same penetrating dissection
their predecessors had applied to the whol-e organ-
ism. They brought us down one degree lower into
the abyss of the infinitely small. And as Pascal,
losing himself in these wonders of the imperceptible,
saw in the body of the mite which is only a point,
" parts incomparably smaller, legs with joints, veins in
the legs, blood in the veins, humours in the blood,
drops in the humours, vapours in these drops," so
contemporary biologists have shown in the epitome
of organism called a cell, an edifice which itself is
marvellously complex.

TJie Cytoplasm. — The observers named above re-
vealed to us the extreme complexity of this organic
unit. Their researches have shown us the structure
of the two parts of which it is composed — the cellular
protoplasm and the nucleus. They have determined
the part played by each in genetic multiplication.
They have shown that the protoplasm which forms the
body of the cell is not homogeneous, as was at first
supposed. The idea which was mooted later, that
this protoplasm was formed, to use Sachs' words, of a
kind of " protoplasmic mud," — i.e., of a dust consisting
of grains and granules connected by a liquid, — is no
longer accurate. There is a much simpler view of the
case. According to Leydig and his pupils, we must
compare the protoplasm to a sponge in the meshes of
which is lodged a fluid, transparent, hyaline substance,
a kind of cellular juice, hyaloplasm. From the

l62 LIFE AND DEATH.

chemical point of view this cellular juice is a mixture
of very different materials, albumens, globulins, carbo-
hydrates, and fats, elaborated by the cell itself It is
a product of vital activity; it is not yet the seat of
this activity. The living matter has taken refuge in
the spongy tissue itself, in the spotigioplasm. »

According to other histologists, the comparison of
protoplasm to a spongy mass does not give the
most exact idea, and, in particular, it does not furnish
the most general idea. It would be far better to say
that the protoplasm possesses the structure of foam
or lather. As was seen by Kunstler in 1880, a com-
parison with some familiar objects gives the best idea.
Nothing could be more like protoplasm physically
than the culinary preparation known as sauce mayon-
naise, made with the aid of oil and a liquid with
which oil does not mix. Emulsions of this kind were
made artificially by Biitschli. He noted that these
preparations mimicked all the aspects of cellular
protoplasm. Thus, in the living cell there is a
mixture of two liquids, non-miscible and of unequal
fluidity. This mixture gives rise to the formation of
little cells. The more consistent substance forms
their supporting framework (Leydig's spongioplasm),
while the other, which is more fluid, fills its interior
(hyaloplasm).

However that may be, whether the primitive
organization of the cellular protoplasm be that of a
sponge, as is asserted by Leydig, or that of a sauce
mayonnaise, as is claimed by Biitschli and Kunstler,
the complexity does not rest there. Further recourse
must be made to analysis. Just as the tissue of a
sponge, when torn, shows the fibres which constitute
it, so the spongioplasm, the parietal substance, is

MORPHOLOGICAL UNITY OF LIVING BEINGS. 163

exhibited as formed of a tangle of fibrils, or better
still, of filaments or ribbons (in Greek, initoine\ which
are called chromatic filaments, because they are deeply
stained when the cell is plunged into aniline dye. In
each of these filaments, the substance of which is
called chromatin, the devices of microscopic examina-
tion enable us to discover a series of granulations like
beads on a string, the microsomes or bioblasts, con-
nected one with the other by a sort of cement,
Schwartz's linin, which is a kind of nuclein.

And let us add, to complete this summary of the
constitution of cellular protoplasm, that it presents, at
any rate at a certain moment, a remarkable organ,
the centrosome, which plays an important part in
cellular division. Its pre-existence is not certain.
Some writers make it issue from the nucleus. At the
moment of cellular division it appears like a com-
pressed mass of granulations, which may be deeply
stained. Around it is seen a clear unstainable zone,
called the attraction-sphere ; and finally, beyond this
is a crown of striae, which diverge like the rays of a
halo — i.e., the aster. In conclusion, there are yet in
the cellular body three kinds of non-essential bodies:
the vacuoles, the leucites, and various inclusions. The
vacuoles diXQ. cavities, some inert, some contractile; the
leucites are organs for the manufacture of particular
substances; the inclusions are the manufactured pro-
ducts, or wastes.

The Nucleus. — Every cell capable of living,
growing, and multiplying, possesses a nucleus of
constitution very analogous to the cellular mass
which surrounds it. The anatomical elements in
which no nucleus is found, such as the red globules
of blood in adult mammals, are bodies which are

164 LIFE AND DEATH.

certain, sooner or later, to disappear. There is there-
fore no real cell without a nucleus, any more than
there is a nucleus without a cell. The exceptions to
this law are only apparent. Histologists have
examined them one by one, and have shown their
purely specious character. We may therefore lay
aside, subject to possible appeal from this decision,
organisms such as Haeckel's monera and the problem
of finding out if bacteria really have a nucleus. The
very great, if not the absolute generality of the
nuclear body, must be admitted.

It hence follows that there is a nuclear protoplasm
and a nuclear juice, just as we have seen that there is a
protoplasm and a cellular juice. What was just said of
the one may now be repeated of the other, and perhaps
with even more emphasis. The nuclear protoplasm
is a filamentary mass sometimes formed of a single
mitome or cord, folded over on itself and capable of
being unrolled. The mitome in its turn is a string
of microsomes united by the cement of the linin.
These are the same constituent elements as before,
and the language of science distinguishes them one
from the other by a prefix to their name of the words
cyto or karyo, which in Greek signify cell and nucleus,
according as they belong to one or the other of these
organs. These are mere matters of nomenclature,
but we know that in the descriptive sciences such
matters are not of minor importance.

We have just indicated that in a state of repose, —
that is to say, under ordinary conditions, — the structure
of a nucleus reproduces clearly the structure of the
cellular protoplasm which surrounds it. The nuclear
essence is best separated from the spongioplasm.
It takes more clearly the form of a filamentary

MORPHOLOGICAL UNITY OF LIVING BEINGS. 165

thread, and the filaments themselves (mitome) show
very thick chromatic granulations, or microsomes,
connected by the linin.

At the moment of reproduction of the cell these
granulations blend into a stainable sheath which
surrounds the filaments, and the latter dispose them-
selves so as to form a single thread. This chromatic
filament, which has now become a single thread, is
shortened as it thickens {spireme) ; it is then cut into
segments, twelve or twenty-four in the case of animals
and a larger number in the case of plants. These
are chro7Hoso7nes, or nuclear segments, or chromatic
loops. Their part is a very important one. They
are constant in number and permanent during the
whole of the life of the cell. Let us add that the
nucleus still contains accessory elements (nucleoli).

The Role of the Nucleus. — Experiment has shown
that the nucleus presides over the nutrition, the
growth, and the conservation of the cell. If, following
the example of Balbiani, Gruber, Nussbaum, and
W. Roux of Leipzig, we cut into two a cell without
injuring the nucleus, the fragment which is denuded
of the nucleus continues to perform its functions for
some time in the ordinary manner, and in some
measure in. virtue of its former impulse. It then
declines and dies. On the contrary, the fragment
provided with the nucleus repairs its wound, is
reconstituted and continues to live. Thus the nucleus'
takes a very remarkable part in the reproduction of
the cell, but it is still a matter of uncertainty whether
its role is here subordinated to that of the cellular
body, or if it is pre-eminent. However that may be,
it follows from this experiment that the nucleus
presents all the characteristics of a vigorous vitality,

l66 LIFE AND DEATH.

and that it is in its protoplasm that the chemists
should be able to find the compounds, the special
albuminoids, which, par excellence, form living matter.

§ 3. The Physical Constitution of Living
Matter. The Micellar Theory.

Physical Constitution of Living Matter. — Micro-
scopic examination does not take us much farther.
The microscope, with the strongest magnification
of which it is capable at present, shows us nothing
beyond these links of aligned microsomes forming
the species of protoplasmic thread or mitome, whose
cellular body is a confused tangle or a very tangled
ball. It is not probable that direct sight can pene-
trate much farther than this. No doubt the micro-
scojae, which has been so vastly improved, is capable
of still further improvement. But these improve-
ments are not indefinite. We have already reached
a linear magnification of 2000, and theory tells us
that a magnification of 4000 is the limit which cannot
be passed. The penetrating power of the instrument
is therefore near its culminating point. It has already
given almost all that we have a right to expect
from it.

We must, however, penetrate beyond this micro-
scopic structure at which the sense of sight has been
arrested. How is this to be done? When observa-
tion is arrested, hypothesis takes its place. Here
there are two kinds of hypotheses, the one purely
anatomical, the other physical. Anatomically, beyond
the visible microsomes there have been imagined
invisible hyper-microscopic corpuscles, the plastidules

MORPHOLOGICAL UNITY OF LIVING BEINGS. 167

of Haeckel, the idioblasts of Hertwig, the pangenes of
de Vries, the plasomes of Wiesner, the gemmules of
Darwin, and the biophores of Weismann.

Biologists who have not got all that they hoped
from microscopic structure are therefore thrown back
on hyper-microscopic structure.

It is very remarkable that all this profound know-
ledge of structure has been so sterile from the point
of view of the knowledge of cellular functional activity.
All that is known of the life of the cell has been
revealed by experiment. Nothing has resulted from
microscopic observation but ideas as to configuration.
When it is a question of giving or imagining an
explanation of vital facts, of heredity, etc., biologists
unable to supply anything beyond the details of
structure revealed by anatomy have had recourse to
hypothetical elements, gemmules, pangenes, bio-
phores, and different kinds of determinants.

Anatomy never has explained and never will ex-
plain anything. "Happy physicists!" wrote Loeb,
" in never having known the method of research by
sections and stainings ! What would have happened
if by chance a steam engine had fallen into the hands
of a histological physicist? How many thousands of
sections differently stained and unstained, how many
drawings, how many figures, would have been pro-
duced before they knew for certain that the machine
is an engine, and that it is used for transforming
heat into motion !"

The study of physical properties, continued on
rational hypotheses, has also thrown some light
on the possible constitution of living matter. The
gap between microscopical structure and molecular or
chemical structure has thus been filled.

12

l68 LIFE AND DEATH.

The consideration of the properties of turgescence
and of swelling, which very generally belong to
organized tissues, and therefore to the organic
substance of protoplasm, has enabled us to obtain
some idea of its ultra-microscopic constitution. If
we wet a piece of sugar or a morsel of salt, before
they are dissolved they absorb and imbibe the water
without sensibly increasing their volume. It is quite
otherwise with a tissue {i.e., with a protoplasm)
when weakened in water as a preliminary. The
tissue, plunged into the liquid, absorbs it, swells, and
often grows considerably. And this water does not
lodge in the gaps, in pre-existing lacunar spaces, for
organic matter presents no gaps of this kind. It
does not resemble a porous mass with capillary
canals, such as sandston'e, tempered mortar, clay, or
refined sugar. The molecules of water interpose
between and separate the organic molecules, thus
increasing by a sort of intussusception the intervals
separating the one from the other — molecular intervals
escaping the senses, as do the molecules themselves
because they are of .the same order of magnitude.

Micellar Theory. — While pondering over this
phenomenon, an eminent physiologist, Nageli, was
led in 1877 to propose his micellar theory. Micellae
are groups of molecules in the sense in which
physicists and chemists use the word. They are
molecular structures with a configuration. They
rapidly absorb water and are capable of fixing a
more or less thick and adherent layer of it to their
surface. In a word, they are aggregates of organic
matter and water.

There is therefore every reason for believing that
the microsomes of spongy protoplasm, the physical

MORPHOLOGICAL UNITY OF LIVING BEINGS. l6g

support or basis of cellular life, are groups of micellce
formed of albuminoid substances and water. These
clustered forms, these micellae, are not absolutely
peculiar to organized matter. Pfeffer, the learned
botanist, has pointed them out under another name,
tagmata, in the membranes of chemical precipitates.

Beyond this limit analysis finds nothing but the
chemical molecule and the atom. So that if we
wish to reconstruct the hierarchy of the materials of
constitution of the protoplasm in order of ascending
complexity, we shall find at the foundation the atom or
atoms of simple bodies. They are principally carbon,
hydrogen, oxygen, nitrogen, the elements of all
organic compounds, to which may be added sulphur
and phosphorus. At the head we have the albu-
minoid molecule, or the albuminoid molecules,
aggregates of the preceding atoms. In the third
stage the micellae or tagmata, aggregates of albu-
minoids and water, are still too small to be observed
by the senses. They unite in their turn to form the
microsomes, the first elements visible to the micro-
scope. The microsomes, cemented by linin, form the
filaments or links which are called mitomes. The
living protoplasm is therefore nothing but a chain, or
tangled, skein, or a spongy skeleton formed by its
filaments.

Such is the typical constitution of living matter
according to microscopic observation, supplemented by
.1 perfectly reasonable hypothesis, which is, so to speak,
only a translation of one of its most evident physical
properties. This relatively simple scheme has become
a complex scheme in the hands of later biologists.
On the micellar hypothesis, which seems almost
inevitable in its character, new hypotheses have been

lyO LIFE AND DEATH.

grafted, merely for the sake of convenience. Hence,
we are led farther and farther from the real truth,
and this is why, in order to explain the phenomena
of heredity, we find ourselves compelled to inter-
calate hypothetical elements between micellae and
the microsome in the higher hierarchy quoted above —
gemmules, pangenes, plasomes, which are only mental
pictures or simple images to represent them.

§ 4. The Individuality of Complex Beings.
Law of the Constitution of Organisms.

Individuality of Complex Beings. — F'rom the cellular
doctrine follows a remarkably suggestive conception
of living beings. The metazoa and the metaphytes —
that is to say, the multicellular living beings which
may be seen with the eyes and do not require the
microscope to reveal them — are an assemblage of
anatomical elements and the posterity of a cell.
The animal or the plant, instead of being an
individual unity, is a " multitude," a term which is
used by Goethe himself when pondering, in 1807, over
the doctrine taught by Bichat ; or, according to the
equally correct expression of Hegel, it is a "nation " ;
it springs from a common cellular ancestor, just as
the Jewish people sprang from the loins of Abraham.

We now picture to ourselves the complex living
being, animal or plant, with its configuration which
distinguishes it from every other being, just as a
populous city is distinguished by a thousand
characteristics from its neighbour. The elements
of this city are independent and autonomous for the
same reason as the anatomical elements of the

MOR'PHOLOGICAL UNITY OF LIVING BEINGS. I7I

organism. Both have in themselves the means of
life, which they neither borrow nor take from their
neighbours nor from the whole. All these inhabitants
live in the same way, are nourished and breathe in
the same manner, all possessing the same general
faculties, those of man; but each has besides, his
profession, his trade, his aptitudes, his talents, by
which he contributes to social life, and by which in
his turn he depends on it. Professional men, the
mason, the baker, the butcher, the manufacturer, the
artist, carry out different tasks and furnish different
products, the more varied, the more numerous and
the more differentiated, in proportion as the social
state has reached a higher degree of perfection. The
living being, animal or plant, is a city of this kind.

Laiv of the Constitution of Organisms. — Such is
the complex animal. It is organized like the city.
But the higher law of this city is that the conditions
of the elementary or individual life of all the ana-
tomical citizens are respected, the conditions being
the same for all. Food, air, and light must be
brought everywhere to each sedentary element ; the
waste must be carried off in discharges which will
free the whole from the inconvenience or the danger
of such debris ; and that is why we have the different
forms of apparatus in the circulatory, respiratory,
and excretory economy. The organization of the
whole is therefore dominated by the necessities of
cellular life. This is expressed in tJie law of the con-
stitution of organisms formulated by Claude Bernard.
The organic edifice is made up of apparatus and
organs, which furnish to each anatomical element
the necessary conditions and materials for the main-
tenance of life and the exercise of its activity. We

172 LIFE AND DEATH.

now understand what is the life, and at the same
time what is the death, of a complex being. The
life of the complex animal, of the metazoon, is of two
degrees ; at the foundation, the activity proper to
each cell, elementary life, cellular life ; above, the
forms of activity resulting from the association of the
cells, the life of the ivhole, the sum or rather the
complex of elementary partial lives. There is a
solidarity between them produced by the nervous
system, by the community of the general circulatory,
respiratory apparatus, etc., and by the free com-
munication and mixture of the liquids which con-
stitute the media of culture for each cell. We shall
have an opportunity of recurring to current ideas as
to the morphological constitution of organisms.

CHAPTER III.

THE CHEMICAL UNITY OF LIVING BEINGS.

The varieties and essential unity of the protoplasm — Its
affinity for oxygen — The chemical composition of proto-
plasm— Its characteristic substances. — § i. The different
categories of albuminoid substances — Nucleo-proteids —
Albumins and histones — Nucleins. — § 2. Constitution of
nucleins. — .^ 3. Constitution of histones and albumins —
Sthultzenberger's analysis of albumin — Kossol's analysis —
The hexonic nucleus.

The chemical unity of living beings corresponds to
their morphological unity.

Uie Varieties and Essential Unity of tJie Proto-
plasm.—Ox\g esrenti-al feature of the living being is
that it is composed of matter peculiar to it, which is
called living matter, or protoplasm. But this is a
somewhat incorrect way of expressing the facts.
There is no unique living matter, no single proto-
plasm ; their number is infinite, there are as many as
there are distinct individuals. However like one
man may be to another, we are compelled to admit
that they differ according to the substance of which
they are constituted. That of the first offers a certain
characteristic personal to the first, and found in all
his anatomical elements ; similarly for the second.
With Le Dantec we shall say that the chemical
substance of Primus is not only of the substance of
man, but in all parts of his body and in all his con-

173

174 LIFE AND DEATH.

stituent cells it is the exclusive substance of Primus;
and, in the same way, the living matter of another
individual Secundus will carry everywhere his per-
sonal impress, which differs from that of Primus.

But it is none the less true that this absolute
specificity is based with certainty only on differences
which from the chemical point of view are exceedingly
slight. All these protoplasms have a very analogous
composition. And, if we regard as negligible the
smallest individual, specific, generic, or ordinal varia-
tions we may then speak in a general manner of
protoplasm or living matter.

Experiment shows us, in fact, that the real living
substance — apart from the products it manufactures
and can retain or reject — is in every cell tolerably
similar to itself The fundamental chemical re-
semblance of all protoplasms is certain, and thus
we may speak of their typical composition. We
may sum up the work of physiological chemistry for
the last three quarters of a century by affirming that
it has established the chemical unity of all living
beings — that is to say, a very notable analogy in the
composition of their protoplasm.

This living matter is essentially a mixture of the
proteid or albuminoid substances, to which may be
added other categories of immediate principles, such
as carbohydrates and fatty matters. But the latter
are of secondary importance. The essential element
is the proteid substance. The most skilful chemists
have tried for more than half a century to discover
its composition. Only during the last few years
— thanks to the researches of Kossel, the German
chemist, following on those of Schultzenberger and
Miescher — we are beginning to know the outer walls

THE CHEMICAL UNITY OF LIVING BEINGS. 175

or the framework of the albuminoid molecule; in
other words, its chemical nucleus.

Physical Characters of Protoplasm. — About i860
Ch. Robin thought that he had defined living matter
sufficiently — or, at least, as perfectly as could be
expected at that time — by attributing to it three
physical characteristics. They were : — Absence of
homogeneity, molecular symmetry, and the association
of three orders of immediate principles — albuminoids,
carbohydrates and fats. These characteristics assist,
but do not suffice, to define the organization.

No doubt the characteristics must be completed by
the addition of a certain number of more subtle
physical features.

One of them refers to the structure of protoplasm
as revealed by the microscope. Throughout the
whole of the living kingdom, from the bacteria studied
by Kunstler and Busquet to the most complicated
protozoa, protoplasmic matter presents the same
constitution, and in consequence, this structure of
the protoplasm must be considered as one of its
distinctive characters. It is not homogeneous ; it
is not the last term of the visible organization : it is
itself organized. Experiment shows that it does not
resist breaking up or crushing. Mutilations cause
it to lose its properties. As for the kind of structure
that it presents, it may be expressed by saying that it
is that of a foamy emulsion.

We saw above that our knowledge as to the physical
condition of protoplasm has been completed by the
theories of Biitschli's micellae or Pfefifer's tagmata.

Properties of the Protoplasm. Its Affinity for
Oxygen. — From the chemical point of view, living
matter presents a very remarkable property — namely,

176 LIFE AND DEATH.

a great affinity for oxygen. It absorbs it so greedily
that the gas cannot remain in a free state in its
neighbourhood. Living protoplasm, therefore, exer-
cises a reducing power. -But it does not absorb
oxygen in this way for Its own advantage ; oxygen
is not absorbed, as was supposed thirty years ago, to
supply fuel wherewith to burn the protoplasm. The
products are not those of its oxidation, of its own
disintegration. They are the products of combustion
of the reserve-stuff which is incorporated in it.
These substances have been supplied to it from
without, like the oxygen itself, with the blood. This
was proved by G. Pfliigcr in 1872 to 1876. The
protoplasm is only the focus, the scene, or the
factor of combustion. It is not its victim, it does
not itself furnish the fuel. It works like the chemist,
who obtains a reaction with the substances that are
given to him.

As for the reducing power of protoplasm, A.
Gautier in 1881 and Ehrlich in 1890 have given fresh
proofs. A. Gautier in particular has insisted that the
phenomena of combustion take place, so to speak,
outside the cell, and at the expense of the products
which surround it ; while on the contrary the really
active and living parts of the nucleus and of the
cellular body, work protected by the oxygen, as in the
case of anaerobic microbes.

This result is of great importance. Burdon Sander-
son, the late learned professor of physiology at the
University of Oxford, has not hesitated to compare
it to the discovery of respiratory combustion by
Lavoisier. There is no doubt some exaggeration in
the comparison ; but there is, on the other hand, no
less exaggeration in supposing that it is not of great

THE CHEMICAL UNITY OF LIVING BEINGS. I77

importance. We may no longer in these days speak
without reservation of the vital vortex of Cuvier, and
of the incessant twofold movement of assimilation
and dissimilation which is ever destroying living
matter and building it up again. In reality, the
living protoplasm varies very little; it only under-
goes oscillations of very slight extent; it is the
materials, the reserve stuff on which it operates, which
are subject to continual transformations.

Chemical Composition of Protoplasm. — One of the
the three characters attributed by Ch. Robin to living
matter was its chemical composition, of which little
was known in his time. He insisted on the constant
presence in the living elements of three orders of
immediate principles — proteid substances, carbo-
hydrates, and fatty bodies. In reality the proteid
substances, or albuminoids, alone are characteristic.
The two other groups, carbohydrates and fatty bodies,
are rather the signs and the products of the vital
activity, than constituents of the matter on which it is
exercised.

It is therefore on the knowledge of the proteid
substances that all the sagacity of biological chemists
has been exercised. Their efforts for thirty years,
and particularly in the last few years, have not been
barren ; they enable us to give a first rough sketch of
the constitution of these substances.

§ I. The Characteristic Substances of the
Protoplasm. The Nucleo-Proteids.

The Different Categories of Albuminoid Substances.
— Albuminoid or proteid substances are extremely
complex compounds, much more so than any of those

178 LIFE AND DEATH.

which are being constantly studied by the chemist.
They also are to be found in great variety. It has
been difficult to separate them one from the other, to
characterize them rigorously, or, in other words, to
classify them. However, it has been done now, and
we distinguish three classes which are differentiated
at once from the physiological and from the chemical
points of view. The first comprises the complete or
typical albuminoids. They are the proteids or micleo-
albiiminoids. They are to be found in the most active
and most living parts of the protoplasm, and therefore
in the spongioplasm of the cell and around the
nucleus. The second group is formed of albumins
and globulins, compounds already simpler, fragments
derived from the destruction of the preceding, into
which they enter as constituent elements. In the
isolated state they do not belong to the really living
protoplasm; they exist in the cellular juice, in the
interstitial and circulating liquids in the blood and in
the lymph. The third category comprises real but
incomplete albuminoids. They are to be found in
the portions of the economy which have a specialized
or attenuated life, and are destined to serve as a
support to the more active elements — i.e., they con-
tribute to the building up of the bony, cartilaginous,
conjunctive, elastic tissues. They are called albii-
moids. It is naturally the first group, that of the
proteids — i.e., of the complete and characteristic com-
pounds of the living substance — upon which the
attention of the physiologists must be fixed. It is
only quite recently that the clear definition of these
substances has been given, and proteid compounds
detected in the confused mass.

The Nucleo-proteids. — This progress in the char-

THE CHEMICAL UNITY OF LIVING BEINGS. 179

acterization and specification of the proteids required
in the first place a knowledge of two particular com-
pounds, the nucleins and the histones. This did not
become possible until after the researches of Miescher
and Kossel on the nucleins, which went on from 1874
to 1892, and those of Lilienfeld and d'Yvor Bang on
the histones, from 1893 to 1899. The complete
albuminoids are constituted by the combination of
two kinds of substances — albumins or histones on the
one hand, and nucleins on the other. By combining
solutions of albumins or histones with solutions of
nuclein, the synthesis of the proteid is effected. The
study of the properties and characteristics of these
nucleo-albumins and nucleo-histones is going on at
the present moment. It is being carried out with
much method and with wonderful patience by the
German school.

All the proteids contain phosphorus in addition to
the five chemical elements, carbon, oxygen, hydrogen,
nitrogen, and sulphur, which are common to the
other albuminoids. Another interesting feature in
their history is that the action of the gastric juice
divides them into their two constituents: — the nuclein,
which is deposited and resists the destructive action
of the digestive liquid, and the albumin or histone,
which on the contrary experiences this action with
the usual consequences. Thus the gastric juice
furnishes a process which is very simple and very
convenient in the analysis of the proteids.

Localization of the Nudeo-Proteids. — What we said
before as to the important physiological role of the
cellular nucleus may arouse the expectation that in it
will be found the living matter which is chemically
the most differentiated, the albuminoids of highest

l8o LIFE AND DEATH.

rank — i.e., the nucleo-proteids and their constituents.
Not that they would not be found in the protoplasm
of the rest of the cell, but there is certainly a risk
that they would be less concentrated there and more
blended with accessory products ; they are there con-
nected with much more secondary vital functions.
This conclusion inspired the early researches of Pro-
fessor Miescher, of Basle, in 1874, and, twenty years
later, those of Professor Kossel, one of the most
eminent physiological chemists in Germany.

In fact, these compounds have been found in all
tissues which are rich in cellular elements with well-
developed nuclei. The white globules of the blood
furnished to Lilienfeld the first nucleo-histone ever
isolated. The red globules themselves, when they
possess a nucleus, which is the case in birds and
reptiles as well as in the embryo of mammals, contain
a nucleo-proteid which was easily isolated by Plosz and
Kossel. Hammarsten, the Swedish chemist, who has
acquired a great reputation from his researches in
other domains of biological chemistry, prepared the
nucleo-proteids of the pancreas in 1893. They have
been pbtained from the liver, from the thyroid
gland (Ostwald), from brewers' yeast (Kossel), from
mushrooms, and from barley (Petit). They have
been detected in starchy bodies and in bacteria
(Galeotti).

§ 2. Constitution of Nucleins.

Constitution of Nucleins. — Our path is already
marked out if we wish to penetrate farther into the
constitution of these proteids, which are the imme-

THE CHEMICAL UNITY OF LIVING BEINGS. lOI

diate principles highest in complexity among those
which form the living protoplasm. We must analyze
the two components, the albumins and the histones on
the one hand, and the nucleins on the other. As for
the nucleins, this has already been done, or very
nearly so.

Kossel, in fact, decomposed the nuclein by a series
of very carefully arranged operations, and has reduced
it step by step to its crystallizable organic radicals.
At each stage that we descend in the scale of
simplification a body appears which is more acid and
more rich in phosphorus. At the third stage we
come to phosphoric acid itself The first operation
divides the nuclein into two substances: the new
albumin and nucleinic acid. After separating these
elements they can be reunited : a solution of albumin
with a solution of nucleinic acid reconstitutes the
nuclein. A second operation separates the nucleinic
acid in its turn into three parts. One is a body of
the nature of the sugars — i.e., a carbohydrate. The
appearance of a sugar in this portion of the molecule
of nucleinic acid is an interesting fact and fertile in
results. The second part is constituted by a mijcture
of nitrogenous bodies, well known in organic chemistry
under the name of xantJiic bases (xanthin, hypo-
xanthin, guanin, and adenin). The third part is a
very acid body and full of phosphorus — thymic acid.
If in a third and last operation the thymic acid is
analyzed, it is finally separated into phosphoric acid
and into thymene, a crystallizable base, and thus we
arc brought back to the physical world, for all these
bodies incontestably belong to it.

l82 LIFE AND DEATH.

§ 3. The Constitution of Histones and
Albumins.

Constitution of Histones. — But we are only half-way
through our task. We are acquainted in its origin
with one of the genealogical branches of the proteid,
the nucleinic branch. We must also learn something
of the other branch, the albumin or histone branch.
But on this side the problem assumes a character of
difficulty and complexity which is admirably adapted
to discourage the most untiring patience.

The analysis of albumin for a long time baulked
the chemist, " Here," said Danilewsky, " we come to
a closed door which resists all our efforts," We know
how vastly interesting what is taking place on the
other side must be, but we cannot get there. We get
a mere glimpse through the cracks or chinks which
we have been able to make.

This analysis of albuminous matter at first requires
great precautions. The chemist finds himself in the
presence of architecture of a very subtle kind. The
molecule of albumin is a complex edifice which has
used up several thousand atoms. To perceive the
plan and structure, it must be ' dismantled and
separated into parts which are neither too large nor
too small. Such careful demolition is difficult.
Processes too rough or too violent will reduce the
whole to the tiniest of fragments. It is a statue
which may be reduced to dust, instead of being
separated into recognizable fragments, easily fitted in
place along their fractured faces.

Analysis of Albumin by ScJiUtzenberger. — Schiitzen-
berger, a chemist of great merit, attempted (about

THE CHEMICAL UNITY OF LIVING BEINGS. 183

1875) this thankless task. Others before him had
experimented in various ways. Two Austrian
scientists, Hlasitwetz and Habermann, in 1873, and
a h'ttle later Drechsel in 1892, had used concen-
trated hydrochloric acid to break down albumin.
They also employed bromine for the same purpose.
More recently Fuerth had used nitric acid with a
similar object. Schlitzenberger tried another way.
The battering ram which he used against the edifice
of albumin was a concentrated alkali, baryta. He
warmed the white of an egg with barium hydrate
in a closed vessel at a temperature of 2co°. The
albumin of egg then divides into a certain number of
simpler groups. The difficulty is to isolate and to
recognize each part in this mass of the materials of
demolition. That can be done by the aid of the
processes of direct analysis. By mentally combining
these different fragments, the original building is
reconstructed. This method of demolition is certainly
too rough and violent. Schiitzenberger's operation
gives us very fine fragments — small molecules of free
hydrogen, of ammonia, of carbonic, acetic, and oxalic,
acids which reveal extreme pulverization. These
products represent about a quarter of the total mass.
The other three-quarters are formed of larger frag-
ments, the examination of which is most instructive.
They belong to four groups. The first comprises five
or six bodies, amido-acids or leucins. It proves the
existence in the molecule of albumin of compounds of
the series of fats — i.e.^ arranged in an open chain.
The second group is formed by tyrosin and kindred
products — i.e., by the bodies of the aromatic series,
which force us to acknowledge the presence in the
molecule of albumin of a benzene nucleus. The third

13

184 LIFE AND DEATH.

group forms around the nucleus known to chemists
under the name of pyrrol. The fourth comprises
bodies such as the glucoproteins, connected with the
sugars, or carbohydrates.

Does the fact that the molecule of albumin is
destroyed in producing these compounds raise the
question as to whether it implies the idea that in
reality they pre-exist in it? Chemists are rather
inclined to admit this. However, the conclusion does
not appear to be permissible. Duclaux considers it
doubtful. It is not certain that all these fragmentary
bodies pre-exist in reality, and it is no more certain
that a simple bringing of them together represents
the primitive edifice. Materials of demolition from a
house that has been pulled down give no idea of its
natural architectural character. There is only one
way of justifying the hypothesis, and that is to re-
constitute the original molecule of albumin by bring-
ing the fragments together. We have not got to that
stage yet. The era of syntheses of such complexity
is more or less near, but it has certainly not yet
begun.

Moreover, it is not correct to say that the simple
juxtaposition of the surfaces of fracture will reproduce
the initial body. The fragments, so far as analysis
has obtained them, are not absolutely what they might
have been in the original structure. There they
adhered the one to the other, not only by the mere
contact of their surfaces of fracture, as is supposed,
but in a slightly more complex manner. The frag-
ments of the molecule are joined by bonds. We can
picture them to ourselves by supposing these bonds
to be like hooks. The hooks, which could only be
broken by violence, are called by the chemists

THE CHEMICAL UNITY OF LIVING BEINGS. 185

satisfied atoinicities. These atomicities, set free by
the breaking up, cannot remain in this condition ;
they must be satisfied anew. The hook tries to attach
itself. In Schutzenberger's experiment the addition,
of water provides for this necessity. A molecule of
water (H,0) splits into two, the hydrogen (H) on the
one side and the hydroxyl (OH) on the other. These
two elements cling to the liberated bonds of the
fragments of the molecule of albumin, and thus
the bodies were found complete. Schutzenberger's
experiment was too violent, too radical, and it gave
too large a number of fragments, with their free hooks
and atomicities unsatisfied, for rather a large pro-
portion of the water added disappeared during the
experiment. In one case this quantity was as much
as 17 grammes per 100 grammes of albumin. The
molecules of this water were employed in the
reparation of the incomplete fragmentary molecules
of the albumin.

It follows that Schutzenberger's experiment gave
too large a number of very small pieces corresponding
to far too great a pulverization. The very small frag-
ments are the molecules of acids such as acetic acid,
oxalic acid, carbonic acid, molecules of ammonia,
and even of hydrogen, which we know we are setting
free.

But, apart from these products which represent a
quarter of the molecule of albumin submitted to
analysis, the other three quarters represent larger
fragments which may be considered as the real
constituents of the building. Thus we find four
kinds of groups which may be accepted as natural.
The first of these groups is that of the leucins or
amido-acids. It proves the existence in the molecule

l86 LIFE AND DEATH.

of albumin of compounds of the fatty series. There
is also an aromatic group — a pyridine group — and a
group belonging to the category of sugars. Imagine
a certain grouping of these four series. This would
be the nucleus of the molecule of albumin. If we
graft on to this nucleus, on to this framework as it
were, so many annexes, or lateral chains, the building
will be loaded with embellishments ; it will have
been made unstable and ipso facto appropriate for the
part that it plays in the incessant transformations
of the organism.

KosseVs Analysis. Hexonic Nucleus. — Kossel has
approached the problem in another fashion. He
did not attempt to attack the albumin of the ^^'g.
This body is, in fact, a heterogeneous mixture as
complex as the needs of the embryo of which it forms
the food. Kossel tried a physiologically simpler
albuminoid. He got it from an anatomical element
having no nutritive role, of a very elementary
organization and physiological functional activity,
and yet one of energetic vitality — the male generating
cell. Instead of the hen's ^go he therefore analyzed
the milt of fish, and, in the first place, of salmon. As
was to be expected from what has been said of the
proteids, this living matter gives a combination of
the nuclein, already known, with an albumin. The
latter is abundant, forming a quarter of the total
mass. Its reaction is strongly alkaline, which is the
general characteristic of the variety of albumin known
by the name of histones. Miescher, the learned
chemist of Basle, who had noticed this basic albumin
when working on the Rhine salmon, gave it the name
of protamin. This is the substance submitted by
Kossel to analysis in preference to the albumin of

THE CHEMICAL UNITY OF LIVING BEINGS. 187

egg, SO dear to the chemists who had preceded him.
The disintegration of this molecule, instead of giving
the series of bodies obtained by Schiitzenberger,
gave but one, a real chemical base, arginin. At the
first trial the albumin examined was reduced to a
simple crystallizable element. The conclusion was
obvious. The protamin of salmon is the simplest of
albumins. To form this elementary proteid substance
a hexonic base with water is all that is required.

Continuing on these lines other male generating
cells were examined and a series of protamines con-
structed on the same type was found, and these
albuminous bodies proved to be formed of a base or
mixture of analogous hexonic bases : arginin, histi-
din, and lysin — all bodies closely akin in their pro-
perties and entirely belonging to the physical world.

Once aware of the existence of this fundamental
nucleus, chemists found it in the more complex
albumins where it had been missed. It was found in
the albumin of z^^ hidden under the mass of other
groups. It was recognized in all animal or vegetable
albumins. The nuclei of Schiitzenberger may be
missing. Hexonic bases are the constant and
universal element of all varieties of albumins. They
prevail in the chemical nucleus of the albuminous
molecule, and perhaps as is suggested by Kossel,
they may form it exclusively. All the other elements
are superadded and accessory. The essential type of
this molecular edifice, sought for so long, is known at
last.

Conclusion. — To sum up, the chemical unity of
living beings is expressed by saying that living
matter, protoplasm, is a mixture or a complex of
proteid substances with an hexonic nucleus.

CHAPTER IV.

THE TWOFOLD CONDITIONING OF VITAL
PHENOMENA. IRRITABILITY.

Appearance of internal activity of the living being— Vital
phenomena regarded as a reaction of the ambient world. —
§ I. Extrinsic conditions — The optimum law. — § 2. Intrinsic
conditions — The structure of organs and apparatus — How
experiment attacks the phenomena of life. Generalization
of the law of inertia — Irritability.

Instability. Mutability. The Appearance of Internal
Activity of the Living Being. — One of the most
remarkable characteristics of the Hving being is its
instability. It is in a state of continual change. The
simplest of the elementary beings, the plastid, grows
and goes on growing and becoming more complex,
until it reaches a stage at which it divides, and thus
rejuvenated it commences the upward march which
leads it once again to the same segmentation. Its
evolution is thus betrayed by its growth, by the
variations of form which correspond to it, and by
its division.

If it be a question of beings higher in organiza-
tion than the cellular element the evolutionary
character of this mutability becomes more obvious.
The being is formed, it grows ; then in most cases,
after having passed through the stages of youth and
adult age, it grows old, declines and dies, and is

188

VITAL PHENOMENA. 1%

disofgatlized after having gone through what we may
call an ideal trajectory. This march in a fixed
direction with its points of departure, its degrees, and
its termination, is a repetition of the path that the
ancestors of the living being have already followed.

Here, then, is a characteristic fact of vitality, or '
rather there are two facts. The one consists in this
morphological and organic evolution, the negation of
immutability, the negation of the indefinite main-
tenance of a permanent state or form which is
regarded, on the contrary, as the condition of inert,
fixed stable bodies, eternally at rest. The other
consists in the repetition, realized by this evolution,
of the similar evolution of its ancestors ; this is a
fact of heredity. Finally, evolution is always in a
cycle — that is to say. that it comes to an end which
brings the course of things to their point of departure.

This kind of internal activity of the living being
is so striking, that not only does it serve us to
differentiate the living being from the inert body,
but it gives rise to the illusion of a kind of internal
demon, vital force, manifested by the more or less
apparent acts of the life of relation, of the motricity,
of the displacement, or by the less obvious acts of
vegetative life.

Vital Phenomena regarded as a Reaction of the
Ambient World. Their Twofold Conditioning. — In
reality, as the doctrine of energetics teaches us, the
phenomena of vitality are not the effect of a purely
internal activity. They are a reaction of the environ-
ment. " The idea of life," says Auguste Comte,
" constantly assumes the necessary correlation of two
indispensable elements : — an appropriate organism
and a suitable environment. It is from the reciprocal

igo LIFE AND DEATH.

action of these two elements that all vital phenomena
inevitably result." The environment furnishes the
living being with three things: — its matter, its
energy, and the exciting forces of its vitality. All
vital manifestation results from the conflict of two
factors : the extrinsic factor which provokes its
appearance ; the intrinsic factor, the very organiza-
tion of the living body, which determines its form.
Bichat and Cuvier saw in the phenomena of life the
exclusive intervention of a principle of action entirely
internal, checked rather than aided by the universal
forces of nature. The exact opposite is true. The
protozoan finds the stimuli of its vitality in the
aquatic medium which is its habitat. The really
living particles of the metazoan — that is to say, its
cells, its anatomical elements — meet these stimuli in
the lymph, in the interstitial liquids which bathe
them and which form their real external environ-
ment.

Auguste Comte thoroughly understood this truth,
and has clearly expressed it in the passage we have
just quoted. Claude Bernard has fully developed it
and given it its classical form.

In order to manifest the phenomena of vitality,
the elementary being, the protoplasmic being, re-
quires from the external world certain favourable
conditions ; these it finds there, and they may be
called the stimuli, or extrinsic conditions of vitality.
This being possesses no initiative or spontaneity in
itself, it has only a faculty of entering into action
when an external stimulus provokes it. This sub-
jtection of the living matter is called irritability.
The term expresses that life is not solely an internal
attribute, but an internal principle of action.

VITAL PHENOMENA. IQI

§ I. Extrinsic Conditions.

Extrinsic Conditiofts. — By showing that every vital
manifestation results from the conflict of two factors :
the extrinsic or physico-chemical conditions which
determine its appearance, and the intrinsic or organic
conditions which regulate its form, Claude Bernard
dealt a mortal blow at the old vitalist theories. For
he has not only asserted the close dependence of the
two kinds of factors, but he has shown them in action
in most physiological phenomena. The study of the
extrinsic or physico-chemical conditions necessary to
vital manifestations teaches us our first truth —
namely, that they are not infinitely varied as might
be supposed. They present, on the contrary, a
remarkable uniformity in their essential qualities.
The fundamental conditions are the same for the
animal or vegetable cells of every species. They are
four in number : — moisture, the air, or rather oxygen,
heat, and a certain chemical constitutioji of the medium,
and the last condition, the enunciation of which
seems vague, becomes more precise if we look at it
a little closer. The chemical constitution of media
favourable to life, the media of culture, obeys three
general laws. It is the knowledge of these laws
which formerly enabled Pasteur, RauHn, Cohn, and
Balbiani to provide the media appropriate to the
existence of certain relatively simple organisms, and
thus to create an infinitely valuable method for
the study of nutrition, etc., — namely, the method of
artificial cultures, numerous developments of which
have been shown us by microbiology and physiology.
The Optimum Laiv. — It has been said, and it is
more than a play on words, that the conditions of

192 LIFE AND DEATH.

the vital medium were the conditions of the juste
milieu. Water is wanted, there must not be too
much or too little. Oxygen is necessary, and also in
certain proportions. Heat is required, and for that,
too, there is an optimum degree. Certain chemical
compounds are needed and, in this respect too, there
must also be optima proportions.

Water is a constituent element of the organisms.
They contain fixed proportions for the same tissue,
proportions varying from one tissue to another
(between | and ■^^. The cell of a living tissue re-
quires around it an aqueous atmosphere, formed by
the different juices of the organism, the interstitial
liquids, the blood, and the lymph. We are deceived
by appearances when we distinguish between aerial,
aquatic, and land-dwelling animals, and when we
speak of the air, the water, arid the land as their
natural environment. If we go to the bottom of
things, and fix our attention on the real living
unities, on the cells of which the organism is composed,
we shall find around them the juices, rich in water,
which are their real environment. If these juices are
diluted or concentrated the least in the world, life
stops. The cell, the whole animal, falls into a state
of latent life, or dies. " All living beings are aquatic,"
said Claude Bernard. " Beings that live in the air are
in reality wandering aquariums," said another physio-
logist. " No moisture, no life," wrote Preyer. The
environment must contain water, but it must contain
it in certain proportions. In the higher animals
there is a mechanism which works automatically to
keep at a constant level the quantity of water in the
blood. Researches on the lavage of the blood (A.
Dastre and Loye) have clearly shown this.

VITAL PHENOMENA. I93

Oxygen is also necessary to life. It is ^o. pabulum
vitcs. But the discovery of the beings called by
Pasteur anaerobia appears to contradict this state-
ment. Pfeffer, the illustrious botanist, was certain,
in 1897, that the dogma of the necessity of oxygen
no longer held good. This is no longer tenable.
In 1898 Beijerinck carried out most careful re-
searches on anaerobia said to have been cultivated
in a vacuum, such as the bacteria of tetanus and the
septic vibrion ; or on those to which oxygen seems to
be a poison, such as the butyric and the butylic
ferments, the anaerobia of putrefaction, the reducing
spirilla of the sulphates. All use free oxygen. They
consume very little it is true ; they are micro-aerobia.
The other organisms, on the contrary, need more.
They are macro-aerobia or simply aerobia. Besides,
if the so-called anaerobia take little or no free
oxygen, it matters little. They take the oxygen
in combination. It may be said with L. Errera
that they have an affinity for oxygen, for they
extract it from its combinations, and that " they
are so well adapted to this mode of existence that
life in the open air being too easy no longer suits
them." There are for the different animal species
different optima of oxygen.

Living beings require a certain amount of heat.
Life, which could not have existed on the globe when
it was incandescent, will not be able to exist when it
is frozen. For each organism and each function
there is a maximum and a minimum of temperature
compatible with activity. There is also an optimum.
For instance, the optimum is 29° C for the germination
of corn.

The condition of the optimum exists in the same

194 LIFE AND DEATH.

way for the chemical composition of the vital medium
— and for the other ambient physical conditions, such
as atmospheric pressure.

It is therefore a law of nniversal scope, a regulating
law, as it were, of life. Life is a function of extrinsic
variables, water, air, heat, the chemical composition of
the medium, and pressure. " Every vital phenomenon
begins to be produced, starting from a certain stage
of the variable (minimum), becomes more and more
vigorous as it increases up to a determinate value
(optimum), weakens if the variable continues to in-
crease, and disappears when it has reached a certain
limiting value (maximum)." This law, proved by
Sachs, the German botanist, in i860, apropos of the
action of temperature on the germination of plants,
by Paul Bert in 1875, apropos of the action of oxygen
and of atmospheric pressure on animals, and already
formulated at that time by Claude Bernard, was
illustrated by Leo Errera in 1895. It is a law of
moderation. It expresses La Fontaine's ^'' rien de
trop" Terence's " ne quid nimisl' the p/Sei' ayav of
Theognis, and the biblical phrase " omnia in mensura
et niimero et pondered L. Errera sees the profound
cause of this optimum law in the properties of the
living protoplasm, which are mean properties. It
is semi-liquid. It is composed of albuminoid sub-
stances, which can stand no extremes either from the
physical or from the chemical points of view.

§ 2. Intrinsic Conditions. The Law of the
Constitution of Organs and Apparatus.

Laiv of the Constitution of Organs and Apparatus. —
If we consider more highly organized beings, the

VITAL PHENOMENA. IQS

influence of the intrinsic conditions appears quite
as clearly. As we have seen, this is so that the
requisite fundamental materials may be spent by
each element in suitable proportions, — water, chemical
compounds, air, and heat, — that organs may be added
to organs, and that apparatus may be set to work in
complex structures. Why a digestive apparatus?
To prepare and introduce into the internal medium
liquid materials which are necessary to life. Why a
respiratory apparatus? To impart the vital gas
necessary to the cells, and to expel the gaseous
excrement, the carbonic acid which they reject.
Why a circulatory apparatus? To transport and
renew* this medium throughout. The apparatus, the
functional wheels, the vessels, the digestive and
respiratory mechanisms do not exist for themselves,
like the random sketches of an artistic nature. They
exist for the innumerable anatomical elements which
people the economy. They are arranged to assist
and more rigorously to regulate cellular life with
respect to the extrinsic conditions which it demands.
They are, in the living body, as in civilized society,
the manufactories and the workshops which provide
for the different members of society dress, warmth,
and food. In a word, the law of the construction of
organisms or of the bringing to perfection of an
organism is the same as the law of cellular life. It
is otherwise suggestive as the law of division of
physiological labour formerly enunciated by Henry
Milne-Edwards; and in every case it has a more
concrete significance. Finally, it brings the organic
functional activity into relation with the conditions of
the ambient medium.

How Experiment acts on the Phenomena of Life. —

196 LIFE AND DEATH.

The two orders of conditions, the one provided by the
being itself, the other by external agents, are equally
indispensable — and therefore of equal importance or
dignity. But they are not equally accessible to the
experimentalist It is not easy to exercise on the
organization direct and measurable actions. On the
contrary, the physical conditions are in the hands
and at the discretion of the experimenter. By them
he may reach the vital manifestations as they appear,
stimulate or check them, defer or precipitate them.
Thus, for instance, the physiologist suspends or re-
establishes at his will full vital activity in a multitude
of reviviscent or hibernating beings, such as grains,
the infusoria capable of ettcystment, the vibrio, the
tardigrade, the cold-blooded animals, and perennial
plants.

The ambient world therefore furnishes to the animal
and to the vegetable, whole or fragmentary, those
materials of its organization which are at the same
time the stimuli of its vitality. That is to say, the
vital mechanism would be a dormant and inert
mechanism if nothing in the surrounding medium
could provoke it to action or give it a check. It
would be a kind of steam engine without coal and fire.

Living matter, in other words, does -not possess real
spontaneity. As I have shown elsewhere, the law of
inertia which it is supposed it obeys with inert bodies
is not special to them. It is applied to the living
bodies whose apparent spontaneity is only an illusion
contradicted by physiology as a whole. All the vital
manifestations are responses to a stimulus of acts
provoked, and not of spontaneous acts. -

Generalization of the Lazu of Inertia in Living
Bodies. Irritability. — In fact, vulgar prejudice opposes

VITAL PHENOMEMA. I97

this view. The opinion of the average man distrusts
it. It apph'cs the law of inertia only to inert matter.
This is because the vital response does not always
immediately succeed the external stimulus, and is not
always proportional to it. But it is sufficient to have
seen the flywheel of a steam engine to understand
that the restitution of a mechanical force cannot be
instantaneous. It is sufficient to have had a finger
on the trigger of a firearm to know that there is no
necessary proportion between the intensity of the
stimulus and the magnitude of the force produced.
Things happen in the living just as in the inert
machine.

The faculty of entering into action when provoked
by an external stimulus has received, as we have said,
the name of irritability. The word is not used of
inert matter. However, the condition of the latter is
the same. But there is no need to affirm its irrita-
bility, because no one denies it. We know perfectly
well that brute matter is inert, that all the manifesta-
tions of activity of which it is the theatre are provoked.
Inertia is for it the equivalent of irritability in living
matter. But while it is not necessary to introduce
this idea into the physical sciences, where it has
reigned since the days of Galileo, it was, on the
contrary, necessary to affirm it in biology, precisely
because it was in biology that the opposing doctrine
of vital spontaneity ruled supreme.

Such was the view held by Claude Bernard. He
never varied on this point. Irritability, said he, is the
property possessed " by every anatomical element
(that is to say, the protoplasm which enters into its
constitution) of being stimulated into activity and of
reacting in a certain manner under the influence of

198 LIFE AND DEATH.

the external stimuli." He could not claim that this
was a distinguishing characteristic between living
bodies and brute bodies, and that all the less because
he always tried to efface on this point the distinctions
which were current in his time, and which were
established by Bichat and Cuvier. And so also Le
Dantec does not seem to have thoroughly grasped
the ideas of the celebrated physiologist on this point
when he asserts, as if he were thereby contradicting
the opinion of Claude Bernard and his school, that
irritability is not something peculiar to living bodies.^

^ These ideas are clearly brought to light in a series of
articles in the Revue Philosophiqiie, published in 1879 under
the title of " La probleme physiologique de la vie," and endorsed
by A. Dastre in his commentary on the Phc'nomenes comvnnts
aux animaux et aux plant es.

CHAPTER V.

THE SPECIFIC FORM. ITS ACQUISITION.
ITS REPARATION.

§ I. Specific form not special to living beings — Connected with
the whole of the material conditions of the body and the
medium — Is it a property of chemical substance? — ^ 2.
Acquisition and re-establishment of the specific form —
Normal regeneration — Accidental regeneration in the pro-
tozoa and the plastids — In the metazoa.

§ I. The Specific Form.

The Specific Form is not Peculiar to Living Beings.
— The position of a specific form — the acquisition of
this typical form progressively reah'zed — the re-estab-
Hshment when some accident has altered it — these
are the features which we consider distinctive of living
beings, from the protophytes and the lowest protozoa
to the highest animals. Nothing gives a better idea
of the unity and the individuality of the living being
than the existence of this typical form. We do not
mean, however, that this characteristic belongs to the
living being alone, and is by itself capable of defining
it. We repeat that this is not a case with any
characteristic. In particular the typical form belongs
to crystal as well as to living beings.

The Specific Fortn depends on the sum of Material
Conditions of the "Body and the Medium. — The con-
sideration of mineral bodies shows us form dependent

199 14

200 * LIFE AND DEATH.

on the physico-chemical conditions of the body and
the medium. The form depends mainly on physical
conditions in the cases of a drop of water falling from
a tap, of the liquid meniscus in a narrow tube, of a
small navel-shaped mass of mercury on a marble
slab, of a drop of oil "emulsioned" in a solution, and
of the metal which is hardened by hammering or
annealed. In the case of crystals the form depends
more on chemical conditions. It is crystallization
which has introduced into physics the idea that has
now become a kind of postulate — namely, that the
specific form is connected with the chemical composi-
tion. However, it is sufficient to instance the dimor-
phism of a simple body, such as sulphur, sometimes
prismatic, sometimes octahedric, to realize that sub-
stance is only one of the factors of form, and that the
physical conditions of the body and of the medium
are other factors quite as influential.

Is the Specific Form a Pj-operiy of the Chemical
Substance? — How much truer this restriction would
be if we consider, instead of a given chemical com-
pound, an astonishingly complex mixture, such as
protoplasm or living matter, or the more complex
organism still — the cell, the plastid.

Are there not great differences between the sub-
stance of the cellular protoplasm, or cytoplasmic
substance, and that of the nucleus? Should we not
distinguish in the former the hyaloplasmic substance;
the microsomic in the microsomes; the linin between
its granulations; the centrosomic in the centrosome;
the archoplasmic in the attraction sphere; not to
mention the different leucins, the vacuolar juice, and
the various inclusions? And in the nucleus must we
not consider the nuclear juice, the substance of the

THE SPECIFIC FORM. 20I

chromosomes, and that of the nucleoles ? And is not
each of these probably a very complex mixture ?

However, it is to this mixture that we attribute the
possession of a form, in virtue of and by extension of
the principles of crystallization, which definitely teach
us that these mixtures cannot have form ; that form .
is the attribute of pure bodies, and is only obtained
by the separation of the blended parts — i.e., by a
return to homogeneity. There are therefore very
good reasons for hesitating before we transfer the
absolute principle of the dependence between
chemical form and composition, as some philo-
sophical biologists have done, from the physical
sciences — where it is already subject to serious
restrictions — to the biological sciences.

Le Dantec, however, has made this principle the
basis of his biological system. He therefore finds in
the crystal the model of the living being. He thus
gives a physical basis to life.

Is it a question in this system of explaining this
incomprehensible, this unfathomable mystery, which
shows the egg cell attracting to itself materials from
without and progressively building up that amazing
structure which is the body of the animal, the body of
a man, of any given man, of Primus, for example?
It is said that the substance of Primus is specific.
His living substance is his own, special to him; and
that, too, from the beginning of the egg to the end of
its metamorphosis. It only remains to apply to this
substance the postulate, borrowed from crystallo-
graphy, of the absolute dependence of the nature of
substance on the form it assumes. The form of the
body of the animal, of the man, of Primus, is the
crystalline form of their living substance- It is the

202 LIFE AND DEATH.

only form of equilibrium that this substance can
assume under the given conditions, just as the cube is
the crystallized form of sea salt, the only state of
equilibrium of chloride of sodium in slowly evaporated
sea water. Thus the problem of the living form is
reduced to the problem of the living substance, which
seems easier; and at the same time the biological
mystery is reduced to a physical mystery. It is clear
that this way of looking at things simplifies pro-
digiously— and, we must add, simplifies far too much
— the obscure problem of the relation of form to
substance, simultaneously in the two orders of science.
This may be summed up in a single sentence:
There is an established relation between the specific
form and the chemical composition: the chemical
composition directs and implies the specific form.

We need not now examine the basis of this opinion.
If it is nothing but a verbal simplification, a unifica-
tion of the language applied to the two orders of
phenomena, it implies an assimilation of the mechan-
isms which realize them. To the organogenic forces
which direct the building up of the living organisms
it brings into correspondence the crystallogenic forces
which group, adjust, equilibrate, and harmonize the
materials of the crystal.

When it is a question of the application of a
principle such as this, in order to test its legitimacy
we must always return to the experimental founda-
tions. Let us imagine, for example, a simple body,
such as sulphur, heated and brought to a state of
fusion — that is to say, homogeneous, isotropic, in an
undisturbed medium the only change in which will
be a very gradual cooling down. These are the
typical crystallogenic conditions. The body would

THE SPECIFIC FORM. 203

take a given crystalline form. It is from experiments
such as this that we derive the idea of a specific form
connected zvith a chemical constitution.

But in drawing this conclusion our logic is at fault.
The real interpretation suitable to this case, as in all
others, is that the specific form is suitable to the'
substance, and also to the physical, chemical, and
mechanical conditions in which it is placed. And
the proof is that this same substance, sulphur, which
takes the prismatic form immediately after fusion,
will not retain that form, but will pass on to the
quite different octahedral form.

It is so with the specific form of the living being —
that is to say, with the assemblage of its constituent
materials co-ordinated in a given system — in a word,
with its organization. This is suitable to its sub-
stance, and to all the material, physical, chemical,
and mechanical conditions in which it is placed. This
form is the condition of material equilibrium cor-
responding to a very complex situation, to a sum of
given conditions. The chemical condition is only
one of these. And further, it is hardly proper to
speak of a "chemical substance" when we refer to an
astonishingly complex mixture which is in addition
variable from one point to the other of the living
body. When we thus reduce phenomena to their
original signification, false analogies disappear. To
say with Le Dantec that the form of the greyhound
is the condition of equilibrium of the "greyhound
chemical substance " is saying much ; and too much,
if it means that the body of the greyhound has a
substance which behaves in the same way as homo-
geneous, isotropic masses like melted sulphur and
dissolved salt. It were better to say much less, if it

204 LIFE AND DEATH.

means, as it will in the minds of the physiologists,
that the body of the greyhound is the condition of
equilibrium of a heterogeneous, anisotropic, material
system, subjected to an infinite number of physical
and chemical conditions.

The idea of connecting form, and by that we mean
organization, with chemical composition did not arise
in the minds of chemists or physiologists. Both have
expressed themselves very clearly on this point.

"We must distinguish," said Berthelot, "between
the formation of the chemical substances, the assem-
blage of which constitutes organized beings, and the
formation of the organs themselves. This last problem
does not come into the domain of chemistry. No
chemist will ever claim to have formed in his laboratory
a leaf, a fruit, a muscle, or an organ. . . . But chemistry
has a right to claim that it forms direct principles —
that is to say, the chemical materials which constitute
the organs." And Claude Bernard in the same way
writes: — "In a word, the chemist in his laboratory,
and the living organism in its apparatus, work in the
same way, but each with its own tools. The chemist
can make the products of the living being, but he
will never make the tools, because they are the result
of organic morphology."

§ 2. The Acquisition and Re-establishment
OF THE Specific Form.

Acquisition of the Typical Form. — The acquisition
of the typical form in the living being is the result of
ontogenic work which cannot be examined here. In
the elementary being, the plastid, this work is blended

THE SPECIFIC FORM. 205

with the work of nutrition. It is directed nutrition.
It consists of a simple increase from the moment the
element is born by the division of an anterior element,
and of a necessarily restricted differentiation. It is a.
rudimentary embryogeny. In the complex being,
metazoan or metaphyte, the organism is constituted,
starting from the Q.g^, by the growth, by the biparti-
tion of the elements, and their differentiation, accom-
plished in a certain direction and in conformity with
a given plan. This, again, is directed nutrition, but
here the embryogeny is complex. The directing plan
of operations is no doubt the consequence of the
material conditions realized each moment in the
organism.

Normal Regeneration. — Not only do living beings
themselves construct their typical architecture, but
they re-establish it and continually reconstitute it,
according as accidents, or even ordinary circumstances,
tend to destroy it ; in a word, they become rejuvenes-
cent. This regeneration consists in the reformation
of the parts that are altered or carried away in the
normal play of life, or by the accidents which disturb
its course.

Thus there is a normal physiological regeneration,
which is, so to speak, the prolongation of the onto-
genesis— z>., of the work of formation of the individual.
We have examples in the reconstitution of the skin
of mammals — in the throwing off of the epidermic
products constantly used up in their superficial and
distal parts and regenerated in their deeply-seated
parts ; in the loss and the renewal of teeth at the
first dentition and in certain fish in the fact of
successive dentitions ; in the periodical renewal of
the integument in the larvce of insects, and in the

206 LIFE AND DEATH.

crustaceae; and finally in the destruction and the
neo-formation of the globules of the blood of verte-
brates, of the glandular cells, and of the epithelial
cells of the intestine.

Accidental Regeneration in Protozoa and Plastids. —
There is also an accidental regeneration which more or
less perfectly renews the parts that are lost. This
regeneration has its degrees, from the simple cicatriza-
tion of a wound to the complete reproduction of the
part cut off It is very unequally developed in
zoological groups even when they are connected.
In the elementary monocellular beings — i.e., in the
anatomical elements and in the protozoa, — the experi-
ments in merotomy, i.e., in partial section, enable us
to appreciate the extent of this faculty of regenera-
tion. These experiments, inaugurated by the re-
searches of Augustus Waller in 1851, were repeated
by Gruber in 1885, continued by Nussbaum in 1886,
Balbiani in 1889, Verworn in 1891, and have been
reproduced by a large number of observers. They
have shown that the two fragments cicatrize, and are
repaired, building up an organism externally similar
to the primitive organism, but smaller. The two new
organic units do not, however, behave in the same
way. That which retains the nucleus possesses the
faculty of regeneration, and of living as the primitive
being lived. The protoplasmic fragment, which does
not contain the nucleus, cannot rebuild this absent
organ; and though it has functional activity in most
respects, just as the nucleated fragment, yet it is
distinguished from it in others of great importance.
The anucleated fragment of an infusorian behaves as
the nucleated, and as the whole animal so far as the
movements of the bod^, the cilia, prehension of food.

THE SPECIFIC FORM. 207

evacuation of faeces, and the rhythmical contrac-
tion of the pulsatile vesicules are concerned. But
Balbiani's researches in 1892 have shown us that
secretion, complete regeneration, and the faculty of
reproduction by fission can take place only in the
nucleated fragment — i.e., in the nucleus.

Accidental Reproduction in the Metazoa. — Among
multicellular beings the faculty of reproduction is met
with in the highest degree in plants, where we find it
in the process of propagation by slips. In animals it
is the most marked in Ccelenterata. Trembley's
experiments are a striking instance. We know that
when the hydra is cut into tiny pieces it reproduces
exactly as many complete beings. Among the
worms, Planaria afford a similar example. Every
fragment, provided its volume is not less than a tenth
of that of the whole, can reproduce a complete, entire
being. The snail can produce a large part of its head,
including the tentacles and the mouth. Among the
Tritons and the Salamanders the faculty of regenera-
tion reproduces the limbs, the tail, and the eye. In
the Frog family, on the contrary, the work of re-
generation does not go beyond cicatrization, and it is
the same with Birds and Insects.

It is really startling to see in a vertebrate like the
Triton the stump of an arm with its fragment of
humerus reproducing the forearm and the hand in all
their complexity, with their skeleton, blood vessels,
nerves, and teguments. We say that the limb has
budded, as if there were a germ of it which develops
like the seed of a plant, or as if each transverse portion
of the limb, each slice, so to speak, could re-form the
slice that follows.

The mechanism of generation and that of regenerjgi'

208 LIFE AND DEATH.

tion alike raise problems of the highest importance.
Does the part become regenerated just as it was
formed at first ? Does the regeneration repeat the
ontogeny? Is it true that a lost organ is never re-
generated (the kidney for instance) ? Does the-
symmetrical organ enjoy a compensating and hyper-
trophic development, as Ribbert has asserted ? And
further, if the organ be removed and transplanted to
another position, can it be grafted there, as Y. Delage
maintains? These are very important questions; but
if we dwell upon them, we shall be diverted from our
immediate object. Our task is to look at these facts
from the point of view of their significant and char-
acteristic meaning in vitality. Flourens invoked on
their behalf the intervention of vital forces, plastic
and morplioplastic. But, as we shall see later, these
phenomena of cicatrization, of reparation, of re-
generation, these more or less complete efforts for
the re-establishment of the specific form, although
they are found in all living beings in different degrees,
are not exclusively confined to them. We find them
again in some representatives of the mineral world —
in crystals, for instance.

CHAPTER VI.

NUTRITION.

FUNCTIONAL ASSIMILATION. FUNCTIONAL DESTRUC-
TION. ORGANIC DESTRUCTION. ASSIMILATING
SYNTHESIS.

The extreme importance of nutrition— § i. Effect of vital
activity — Destruction or growth — Distinction between the
living substance and the reserve-stuff mingled with it —
Organic destruction — Destruction of reserve-stuff — De-
struction of living matter — Growth of living matter —
§ 2. The two categories of vital phenomena — Foundations
of the idea of functional destruction — The two kinds of
phenomena of vitality — Criticism of Claude Bernard —
Current views — Criticism of Le Dantec's new theory of
life. — § 3. Correlation of the two kinds of vital facts — Law
of connection — Contradictions in the new theory. — § 4. The
characteristics of nutrition — Its definition — Its permanence
— Erroneous idea of the vital vortex — Formative assimilation
of reserve-stuff— Formative assimilation of protoplasm —
•Death, real and apparent. ,

The Immense Importance of Nutrition. — We now
come to the important feature of vitality. All other
characteristics of living matter, its unstable equilibrium,
its chemical and anatomical organization, the acquisi-
tion and the maintenance of a typical form, are only
secondary properties, so to speak, subordinate with
reference to nutrition. Generation itself is only a
mode. Nutrition is the essential attribute of life. It
is life itself.

209

210 LIFE AND DEATH.

Before we define it a few preliminary explanations
are necessary.

The most striking thing in living matter is its
growtJi. An animal, a vegetable, is something which
is first more or less minute, and which grows. Its
characteristic is to expand — from the spore, the seed,
the slip, the Q^g — it grows.

Whether we are dealing with a cellular element, a
plastid, or a complex being, their condition is the
same in this respect. No doubt when the animal or
plant has reached a certain stage of development its
growth is stopped, and for a more or less lengthy
period it remains in the adult stage, in what seems to be
equilibrium. But even then there is no check in the
manufacture of living matter; there is only a com-
pensation between its production and its destruction.

It is important to reduce to order the ideas on this
important subject, which at present are confused,
inconsistent, and contradictory. In biology grievous
confusion reiens.

§ r. Effect of the Vital Activity.
Destruction or Growth?

Distinction between the Living Substance and the
Reserve-stuff mingled with it — The physiology of
nutrition has given rise to a vast body of research
during the last half-century. Physiological schools,
masters and pupils, such as the school at Munich
under Voit and Pettenkofer, Pfluger's at Bonn,
Rubner's, and those of Zuntz and von Noorden at
Berlin, and a large number of zootechnical and "agri-
cultural laboratories through the whole world have for

NUTRITION. 211

years past been engaged in analyzing ingesta and
egesta, in drawing up schedules of nutrition, in order
to determine the course of decomposition and re-
constitution of the living material.

If I were asked what, in my opinion, is the most
general result of all this labour, I would reply that it
has affirmed and corroborated the important distinc-
tion which must be drawn between living substance,
properly so called, and reserve-stuff. The latter, the
reserve-stuff of albuminoids, carbohydrates, and fats,
are so intimately intermingled with the living sub-
stance that they are in most cases very difficult to
distinguish from it.

Organic Destruction. — A second point, which is
placed equally beyond doubt, is that the vital func-
tional activity is accompanied by a destruction of the
immediate principles of the organism, in the direction
of their simplification. This functional destruction
cannot be doubted in the case of differentiated organs
in which the functional activity is evident, inter-
mittent, and in some measure distinct from the other
vital phenomena which take place in them. For
example, in the case of contracting muscles the
respiratory carbonic acid and urinary carbon are the
irrefutable proofs of this destruction : weak in repose,
abundant during activity, and in proportion to it.
There can be no doubt on this point. The truth
laid down by Claude Bernard under the name of
the law of functional destruction has been doubly
consecrated by experiment and theory. According
to the energetic theory, in fact, mechanical and
thermal energies manifested in the vital functional
activity can only have their source in the chemical
energy set free by the destruction of the immediate

212 LIFE AND DEATH.

principles of the organism, reduced to a lower degree
of complexity.

Destruction of Reserve-stuff. — But now the disagree-
ment begins. What are these decomposed, destroyed
principles ? Do they belong to the cellular reserve-
stuff or to the living matter properly so called?
There is no doubt that most of them belong to the
reserve-stuff. For example, this is especially true of
glycogen, which is consumed in muscular contraction
just as coal is consumed in the furnace of the loco-
motive; and glycogen is a reserve-stuff of muscle.
These reserve-stuffs destroyed in the functional
activity can be built up again only during repose.

But it is not yet certain whether the living
matter itself, the active protoplasm, the muscular
protoplasm, takes part in this destruction, whether it
provides it with elements. Experiments have proved
contradictory. Experimenters have isolated the nitro-
genous wastes (urea) after muscular labour, and they
have compared them with the wastes of the period of
repose. These nitrogenous wastes bear witness to the
destruction of albuminoid substances, and the latter
are the constituent principles of living matter. If —
under conditions of sufficient alimentation — the mus-
cular functional activity involves more nitrogenous
waste, i.e., a greater destruction of albuminoids, it
might be supposed that the living material properly
so called has been used up and destroyed for its
own purposes. (And here again there might be a
reserve-stuff of albuminoids, distinct from the living
protoplasm itself, and more or less incorporated
with it.)

But experiment so far has not given decisive results.
The latest experimental researches, such as those of

NUTRITION. 213

Igo Kaup, of Vienna, which date from 1902, tell us as
uncertain a tale as their predecessors. The increase
in the destruction of albumen has not been constant;
the conditions of the observations do not justify our
making an assertion either pro or con.

Destruction of Living Matter. — As no certain
answer is supplied by experiment, theory intervenes
and gives two conflicting answers. The majority of
physiologists are inclined to believe in the destruction
of the living substance as the result of its own func-
tional activity. The functional activity would there-
fore destroy not only the reserve-stuff, but also the
protoplasmic material. This is the current view.
Only this opinion is strongly challenged by the
positive teaching of science. It is certain that this
material, in the muscle, is but little attacked, if it
is attacked at all. We have seen above that the
physiologists, with Pfliiger and Chauveau, are agreed
on this point. The vital functional activity in par-
ticular is destructive to the reserve-stuffs. It does
not destroy them much; it destroys the organic
material still less. Both would be repaired in func-
tional repose.

Growth of Living Matter. — The second assertion is
diametrically opposed to this. Not only, says Le
Dantec, is the muscle not destroyed in the functional
activity, but it grows. Contrary to universal opinion,
the protoplasmic material increases by activity, and it
is destroyed in repose. There would thus be a
general law — the law of ftmctional assimilation. "A
cell of brewers' yeast when introduced into a sugared
must makes this must ferment, and at the same time,
so far from destroying it, it increases it. Now, the
fermentation of the must is exactly the same as the

214 LIFE AND DEATH.

functional activity of the yeast." It is, says the same
author, a mistake to beheve that the phenomena of
functional activity, of vital activity, only takes place
at the price of organic destruction. Here, then, are
these two competing views. They are not so very far
apart as a matter of fact, since the question at issue is
one of deciding between a slight destruction and a
slight growth, but theoretically they are strongly
opposed. Moreover, they are arbitrary, and experi-
ment has not decided between them.

§ 2. THE TWO CATEGORIES OF VITAL PHENOMENA.

Foundation of the Idea of Functional Destruction.
Claude Bernard. — The doctrine of functional de-
struction has been laid down with remarkable power
by Claude Bernard. But the terms in which he has
expressed it in a measure betray the thoughts of the
great physiologist, or, at any rate, overstep the
immediate fact he had in view. " The phenomena
of destruction are very obvious. When movement is
produced, when the muscle contracts, when volition
and sensibility are manifested, when thought is
exercised, when the gland secretes, then the sub-
stance of the muscles, of the nerves, of the brain, ot
the glandular tissue, becomes disorganized, destroyed,
and consumed. So that every manifestation of a
phenomenon in the living being is necessarily con-
nected with an organic destruction." To Claude
Bernard organic destruction is a truth. To Le Dantec
it is an error. Which is right? Clearly Claude
Bernard, He bases his conviction on the analyses
of the materials excreted in the process of physio-

NUTRITION. 215

logical work. The excreta bear witness to a certain
organic demolition. Generalizing this teaching of
experiment the illustrious biologist divined the
fundamental law of energetics before the idea of
energetics had made much way in France. Every
act which expends energy, which produces heat or
motion, any manifestation whatever that may be
looked upon as an energetic transformation, neces-
sarily expends energy, and that energy is borrowed
from the substance of the organism. These sub-
stances are simplified, broken up, and destroyed.
Now the functional activity of the muscle produces
heat and movement in warm-blooded as well as in
cold-blooded animals. The functional activity of
the glands produces heat, as has. been shown by the
celebrated experiments of C. Ludwig on the salivary
secretion, and as is also shown by the study of thermal
topography in the vertebrates. The functional activity
of the nerves and the brain produces a slight quantity
of electricity and heat, as most observers have agreed.
The functional activity of the electrical and of the
photic apparatus also expends energy. Finally, the
eye which receives the photic impression destroys the
purple matter of the retina, and that purple matter,
as we well know, is recuperated in the dark during
the repose of the organ. Everything that is expressed
objectively, everything that is a phenomenon in the
living being — with the exception of growth and
formation, which are generally slow phenomena, and
of which we can only get an idea by the comparison
of successive states — all these energetic manifestations
suppose a destruction of organic matter, a chemical
simplification, the source of the energy manifested.
And that is why material destruction does not merely

15

2l6 LIFE AND DEATH.

coincide with functional activity, but is its measure
and expression.

The Tivo Kinds of Phenomena of Vitality. — Another
point on which Claude Bernard is right and his
opponent is wrong is not less fundamental. What
are we to understand by functional phenomena ?
This is the very point at issue. Now, in the mind of
physiologists, this expression has a perfectly definite
meaning. It is not so with Le Dantec. Physiologists
who have studied animals rather high in organization
— in which the differentiation of phenomena enables
us to grasp the fundamental distinction — have readily
recognized that the phenomena of living beings are
divided into two categories. There are some which
are intermittent, alternative, which take place, or grow
stronger at certain moments, but which cannot be
continuous — they are the functional acts ; there are
others in which this characteristic of explosives,
energetic expenditure and intermittence, do not
appear — they are, in general, the nutritive acts. The
muscle which contracts shows functional activity. It
has an activity and a repose. During this apparent
repose we must not say that it is dead ; it has a life,
but that life is obscure as far as the salient fact of
functional movement is concerned. The salivary
gland which throws up waves of saliva when the food
is introduced and masticated in the mouth, or when
the chord of the tympanum is at work, is in a state of
functional activity ; this is the salient phenomenon.
But before, though nothing, absolutely nothing, was
flowing through the glandular canal, yet the gland
was not reduced to the condition of a dead organ : it
was living a more obscure, a less evident life. The
microscopical researches of Kiihne, Lea, and Langley,

NUTRITION. 217

now universally verified, show us that during this
time of apparent repose the cells were loading up
their granulations and getting ready the materials of
secretion, as just now the muscle at rest was accumu-
lating glycogen and the reserve-stufT which are to be
expended and destroyed in contraction. Similarly,
with regard to the functional activity of the other
glands, of the brain, etc. Claude Bernard was, there-
fore, perfectly right, when he took as his model the
chemists who distinguished between exothermic and
endothermic reactions, and who classed the pheno-
mena of life into two great divisions : those of
functional activity, and those of functional repose.

I St. The phenomena of functional activity "are
those which 'leap to the eyes,' and by which we
are inclined to characterize life. They are con-
ditioned by the effects of wear and tear, of chemical
simplication, and of the organic destruction which
liberates energy." And it must be so, because these
functional manifestations expend energy. These
phenomena, which are the most obvious, are also the
least specific phenomena of vitality. They form
part of the general phenomenality.

2nd. The phenomena which accompany functional
r^/^i-^ correspond to the building up of the reserve-
stuff destroyed in the preceding period, to the organiz-
ing synthesis. The latter remains " internal, silent,
concealed in its phenomenal expression, noiselessly
gathering together the materials which will be ex-
pended. We do not see these phenomena of
organization directly. The histologist and the
embryogenist alone, following the development of
the element or of the living being, sees the changes
and the phases which reveal this silent effort. Here

2l8 LIFE AND DEATH.

is a store of substance ; there, the formation of
an envelope or a nucleus ; there, a division or
multiplication, a renewal." This type of phenomena
is the only type which has no direct analogues :
it is peculiar, special to the living being : what
is really vital is this evolutive synthesis. Life is
creation.

Criticism of Claude Bernard. — All this is perfectly
true. Thirty years of the most intensive scientific
development have run by since these lines were
written, and have not essentially changed the ideas
therein expressed. His work in its broad lines
remains intact. Does that imply, however, that
everything is perfect in detail and expression, and
that there is no reason for making it more precise or
for giving it fresh form ? No doubt this is not so.
Although Claude Bernard contributed to establish
the essential distinction between the real living
protoplasm and the materials of reserve-stuff which
it contains, he has not drawn a sufficiently clear
distinction between what belongs to each of the
categories. He has not specified, in relation to
organic destruction, what bearing it has on the
organic materials of reserve-stuff Sometimes he uses
the term " organic destruction," which is correct, and
sometimes " vital destruction," which is of doubtful
import. Further, he employs an obscure and
paradoxical formula to characterize the obvious but
nevertheless not specific phenomena of organic
destruction, and he says : " life is death."

Current Vieivs. — Nowadays, if I may express a
personal opinion on this important distinction be-
tween functional activity and functional repose, I
should say that after having distinguished between

NUTRITION. 219

the two categories of phenomena we must try to
correlate them. We must try to discover, for
instance, what there is in common between the
muscle in repose and the muscle in contraction, and
to perceive in the muscular tonus a kind of bridge
thrown between these two conditions. The functional
activity would be uninterrupted, but it would have its
degrees of activity. The muscular tonus would be
the permanent condition of an activity which is cap-
able only of being considerably raised or lowered.
Similarly for the glandular functional activity ; the
periods of charge must be connected with the periods
of discharge. In a word, following the constant path
of the human mind in scientific knowledge, after
having drawn the distinctions that are necessary to
our understanding of things, we must obliterate them.
After having dug our ditches we must fill them up
again. After having analyzed wc must synthesize.
The distinction between the phenomena of functional
activity and the phenomena of functional repose or
purely vegetative and nutritive activity, though only
valid in the case of a provisional and approximate
truth, none the less throws light on the obscure
regions of biology.

The succession of energy and repose, of sleep and
awakening, is a universal law, or at least a very
general law, connected with the laws of energetics.
The heart, the lungs, the muscles, the glands, the
brain obey in the most obvious manner this obligation
of rhythmical activity. The reason is clear. It is
because the functional activity involves what is
generally a sudden expenditure of energy, and this
has to be replaced by what is generally a slow
process of reparation. Functional activity is an

220 LIFE AND DEATH.

explosive destruction of a chemical reserve which is
built up again more or less slowly.

Criticism of Le Danteds '' Nezv Theory of Life!' —
Let us now examine the antithesis of Claude
Bernard's views. There are evidently rudimentary
organisms in which the differentiation of the two
categories of phenomena is but little marked ; in
which, apart from the movement, it is impossible to
recognize intermittent, functional activities clearly
distinct from morphogenic activity. It is not in this
domain of the indistinct that we must seek the
touchstone of physiological distinctions. Clearly, we
must not choose these elementary plastids to test
the doctrine of functional assimilation and functional
destruction. But is not this exactly what Le Dantec
did when he began his researches on brewers' yeast?
When we try to examine things, we must choose the
conditions under which they are differentiated, and
not those in which they are confused. And this is
why, in the significant words of Auguste Comte, " the
more complex living beings are, the better known
they are to us." The philosopher goes still farther
in this direction, and adds "directly it is a question
of the characteristics of animality we must start from
the man, and see how those characteristics are little
by little degraded, rather than start from the sponge
and endeavour to discover how these characteristics
are developed. The animal life of the man assists
us to understand the life of the sponge, but the
converse is not true."

When, moreover, we consider a vegetable organism
such as yeast, which derives its energy, not from
itself, not from the potential chemical energy of its
reserve-stuff, but directly from the medium — that is

NUTRITION. 22t

to say, from the potential chemical energy of the
compounds which form its medium of culture, — we
then find ourselves in the worst possible situation for
the recognition of organic destruction. Further, it is
doubly wrong to assert that in so ill-chosen a type ■
the functional phenomena do not result from an
organic destruction — for at first there are no very
distinct functional phenomena here — and, in the second
place, there certainly is organic destruction. The
phenomena of the morphogenic vitality detected in
the yeast are the exact concomitants, or the results,
of the destruction of an organic compound, which in
this case is sugar. The yeast destroys an immediate
principle, and this is the point of departure of its vital
manifestations ; only, it has not, as a preliminary,
clearly incorporated and assimilated this principle.
When, therefore, the functional phenomena are
effaced and disappear, we none the less find pheno-
mena of destruction of organic compounds which are
in a measure, a preface to the phenomena of growth.
This is what happens in the case of brewers' yeast :
and here, again, the two categories of facts exist.
Once more, we find, in the first place, the phenomena
of destruction (destruction of sugar, reduced by
simplification to alcohol and carbonic acid) — pheno-
mena which this time no longer respond to obvious
functional manifestations ; and, in the second place,
the phenomena of chemical and organogenic synthesis,
corresponding to the growth of the yeast and the
multiplication of its protoplasm. The former are no
longer detected, as we have just said, by striking
manifestations. However, it is not true that every-
thing which is visible and which may be isolated
outside the activity of the yeast is part of those

222 LIFE AND DEATH.

phenomena. The boih'ng of the juice or the mash,
the heat given off by the copper, all this phenomenal
apparatus is but the consequence of the production of
the carbonic acid and of its liberations — i.e., the
consequence of the act of destruction of the sugar.
Here is organic destruction with its energetic
manifestations !

This example of the life of brewers' yeast, of the
saccharomyces, specially chosen by Le Dantec as
being absolutely clear and giving the best illustration
of his argument, contradicts him at every point. The
general thesis of this vigorous thinker is that we
cannot distinguish between the two parts of tlic vital
act, organic destruction, and assimilating synthesis ;
that these two acts are not successive ; that they give
rise to phenomenal manifestations equally evident,
apparent, or striking. Now, in the case of yeast, the
phenomenon of destruction is clearly distinct from
that of the assimilating synthesis which multiplies
the substance of the saccharomyces. In fact, the
action is realized by means of an alcoholic diastase
manufactured by the cell ; and Buchner succeeded in
isolating this alcoholic ferment which splits up the
sugar into alcohol and carbonic acid, and also in vitro
and in vivo, makes the vat boil arid heats the liquid.
All the yeast is at work at once, says M. Dantec.
No, and this is the proof.

And, further, Pasteur himself, who had shown the
relation of the decomposition of the sugar to the fact
of the growth of the yeast and of the production
of accessory substances such as succinic acid and
glycerine, always referred to correlation between these
phenomena. The destruction of the sugar is the
correlative of the life of the yeast. This was his

NUTRITION. 223

favourite formula. It never entered his head that
there could be a confusion instead of a correlation,
and that there might be only one and the same act,
the phases of which would be indistinguishable.
This unfortunate idea, which was fated to be so
rapidly contradicted, is due to Le Dantec. Far
from it being the case, Pasteur had distinguished
the ferment function from the life of the yeast.
According to him, the yeast may exist sometimes as
a ferment and sometimes otherwise.

§ 3. Correlation of Two Orders of
Vital Facts.

Jt is this correlation between acts distinct in them-
selves but usually connected that was announced by
Claude Bernard. And, mirabile dictu — and this is the
natural outcome of the perfect sanity of mind of this
great physiologist — it happens that not only Pasteur's
researches, but the development of a new science.
Energetics, and Biichner's discovery lend support to
his views, and that, too, in a field where one would
have thought they had no application. Le Dantec is
wrong when he declares that these ideas only apply to
vertebrates; "It is clear," he says on several occa-
sions, *' that the author has in view the metazoa and
even the vertebrates." Well • ho. All that is general,
universally applicable, and universally true. So that
there are two orders of distinct phenomena ener-
getically opposed and certainly connected. We need
only repeat Claude Bernard's own words quoted by
Le Dantec in order to confute them.

Laiv of Connection of Tzvo Orders of Vital Facts.
— "These phenomena [of organic destruction and of

224 LIFE AND DEATH.

assimilating synthesis] are simultaneously produced
in every living being, in a connection which cannot
be broken. The .disorganization or dissimilation uses
up living matter [by this we must understand the
reserve-stuff, as will be seen later on in the quotation]
in the organs in function: the assimilating synthesis
regenerates the tissues; it gathers together the re-
serve-stuff which the vital activity must expend.
These two operations of destruction and renovation,
inverse the one to the other, are absolutely connected
and inseparable, in this sense at any rate, that de-
struction is the necessary condition of renovation.
The phenomena of functional destruction are them-
selves the precursors and the instigators of material
regeneration, of the formative process which is silently
going on in the intimacy of the tissues. The losses
are repaired as they take place; and equilibrium being
re-established as soon as it tends to be broken, the
body is maintained in its composition."

It is perfectly right and wise to say with Claude
Bernard that the two orders of facts are successive,
and that one is normally the inciting condition of the
other. The possibility of the development of the
yeast when fermentation fails, and the weakness of
this development on the other harrd under these con-
ditions, are an excellent proof of this. The one proves
the essential independence of the two orders of facts,
the other the inciting and provoking virtue of the first
relatively to the second. The experimental truth is
thus expressed with a minimum of uncertainty. We
know the facts which led Le Dantec to formulate his
law of functional assimilation — namely, that the
functional activity is useful or indispensable to the
growth of the organ ; that the organs which are

NUTRITION. 225

functionally active grow, and those which do not act
become atrophied. We are only expressing the facts
when we say that the organic destructions that go on in
the living being (whether at the expense of its reserve-
stuff or at the expense of its medium, or whether it be
even slightly at the expense of the plastic substance
itself) are the antecedent, the inciting agent or the
normal condition of the chemical and organogenic
syntheses which create the new protoplasm.

On the other hand, we are wrong if we hold with
Le Dantec that instead of two chemical operations
there is only one, that which creates the new proto-
plasm. The obvious destruction is neglected ; it is
deliberately passed over. He does not see that it is
necessary to liberate the energy employed in the
construction, by complication, of this highly complex
substance which is the new protoplasm. He really
seems to have made up his mind not to analyze the
phenomenon. If we decline to admit that to the first
act of functional destruction succeeds a second,
assimilation or organogenic synthesis, we are look-
ing at elementary beings, in which the succession
cannot be .grasped, as we look on brewers' yeast.
We not only mean that the morphogenic assimilation
results from the functional activity; we mean that it
results from it directly, immediately, that it is the
functional activity itself Experiment tells us nothing
of all this. It shows us the real facts, the facts of the
destruction of an organic immediate principle, the
sugar, and the fact that an assimilating synthesis is
the correlative of this destruction. Besides, if it is
impossible in examples of this kind to exhibit the
succession, it is perfectly easy in beings of a higher
order. It is, then, clearly seen that the preliminary

226 LIFE AND DEATH.

destruction of a reserve-stuff (and perhaps of a small
quantity of the living substance) precedes and con-
ditions the formation of a greater quantity of this
living matter — in other words, the growth of the
protoplasm of the organ.

Contradictions in the New Theoty. — Moreover, these
mistakes involve those who make them in a series of
inextricable contradictions. Here, for example, is
life; it is found, they say, in three forms: — Life
manifested, or condition i°; latent life, or condition
3°. So far this is the classical theory ; but they add
a condition 2°, which is what might be called patho-
logical or incomplete life. This is defined by the
following characteristic: — That its functional pheno-
mena are identical with those in the first form, but
that they are not accompanied by assimilation and by
protoplasmic growth. But since, they say, growth is
the chemical consequence of the functional activity,
since it is so to speak its metabolic aspect, since it is
confused with it, and inseparable from it, by the
argument — then it is contradictory and logically
absurd to speak of condition 2°. It would be ac-
knowledging in the case of the anucleated merozoite,
for example, a functional activity unaccompanied by
assimilation, yet identical with the functional activity
which is accompanied by assimilation in the nucleated
merozoite. The general movement, that of the cilia,
the taking of food, the evacuation of the faeces, the
contraction of the pulsatile vacuoles, are the same.
And this fact is the best proof that this vital func-
tional activity (with the organic destruction which is
its energetic source) must be distinguished from the
assimilation which usually follows it, and which in
exceptional cases may not follow it.

NUTRITION. 227

VVe shall carry this discussion no farther. We have
examined at some length Le Dantec's views, and we
have contrasted them with the doctrine which has
been current in general physiology since the time of
Claude Bernard, and this comparison does not turn
out quite to their advantage. It was inevitable that
the experimental and realistic spirit which inspired
the doctrine of the celebrated physiologist made his
work really too systematic. His formula, "life is
death," and the form he gave his ideas, are not always
irreproachably correct. They lend themselves at
times to criticism. Sometimes they require commen-
tary. These are errors of detail which Le Dantec
has summarized somewhat roughly. There is no
necessity to do this in his own case. We pay our
tribute to the clearness of his language, although we
believe the foundations of his system are false and
ill-founded. Their rigour is purely verbal. Their
external qualities, their careful arrangement are well
adapted to the seduction of the systematic mind
prepared by mathematical teaching. This new theory
of life is presented with pedagogic talent of the
highest order. We think we have shown that the
foundations are entirely fallacious, in particular the
following: — Vital condition No. 2°; the confusion be-
tween functional activity and assimilating synthesis ;
the so-called absolute connection between morpho-
geny and chemical composition ; the fundamental
distinction between elementary life and individual life.

§ 4, Characteristics of Nutrition.

Definition of Nutrition. — As we have just seen, the
organism is the scene of chemical reactions of two

228 LIFE AND DEATH.

kinds, the one destructive and simplifying, the other
synthetic, constructive, or assimilating. This totality
of reactions constitutes nutrition. Hence the two
phases that it is convenient to consider in this func-
tion— assimilation and disassimilation. This twofold
chemical movement or metabolism corresponding to
the two categories of vital phenomena, of destruction
(catabolism) and of synthesis (anabolism) is therefore
the chemical sign of vitality in all its forms. But it
is clear that disassimilation or organic destruction,
which is destined to furnish energy to the organism
for its different operations, reappears in the plan of
the general phenomena of nature. It is not specific-
ally vital in its principle. Assimilation, on the other
hand, is in this respect much more characteristic.

To some physiologists nutrition is only assimila-
tion. Of the two aspects of metabolism they consider
only one, the most typical, Ad-similare, to assimilate,
to restore the substance borrowed from the ambient
medium, the alimentary substances, similar to living
matter, to make living matter of them, to increase
active protoplasm — this is indeed the most striking
phenomenon of vitality. To grow, to increase, to
expand, to invade, is the law of living matter.
Assimilation, nutrition in its essentials, is, according
to the definition of Ch. Robin, "the production by the
living being of a substance identical with its own."
It is the act by which the living matter, the proto-
plasm of a given being, is created.

Permanence in Nutrition. — Nutrition presents one
quite remarkable character — permanence. It is a vital
manifestation, a property if we look at it in the cell,
in the living substance, a function if we consider it in
the animal or in the plant as a whole, which is never

NUTRITION. • 229

arrested. Its suspension involves ipso facto ihe sus-
pension of life itself. It is, in the words of Claude
Bernard, that property of nutrition " which, as long as
it exists in an element, compels us to believe that this
element is alive, and which, when it is absent, compels
us to believe that it is dead. It dominates all others
by its generality and its importance. In a word, it is
the absolute test of vitality."

Biological Energetics shows the Importance of
Nittrition. — We have indicated in advance the reason
of its importance, showing that its two phases, cjis-
assimilation and assimilation, are the energetic
condition of the two kinds of vital phenomena
which we can distinguish.

Nutrition is a manufacture of protoplasm at the
expense of the materials of the cellular ambient
medium, which are assimilated — i.e., made chemically
and physically similar to living matter and to the
reserves it stores up. This operation, which is
peculiarly chemical, is therefore indicated by the
borrowing of materials from the external world, a
borrowing which is always going on, because the
operation is permanent, and,, let me add, because of
the continual rejection of the waste products of
this manufacture. Our formula is : — Nutrition is a
chemistry which persists.

The Idea of the Vital Vortex is Erroneous. — Here
the effect has hidden the cause from the eyes
of the biologists. They have been struck by the
incessant entry and exit, by the never-ceasing passage,
by the cycle of matter through the living being
without guessing its why and wherefore ; and they
have taken as a picture of the living being a vortex
in which the essential form is maintained while the

230 LIFE AND DEATH.

matter, which is accessory, flows on without a check.
This is Cuvier's vital vortex. Rut for what purpose
is this circulating matter used ? They thought that
it was employed entirely for the reconstitution of
the living substance, continually and inevitably de-
stroyed by the vital Minotaur.

Destruction of Reserve-stuff. — Here again there is
a mistake. Really living substance is but little
destroyed, and consequently requires very little
renewal by the functional activity of the animal
machine. Its metabolism — destruction and renewal
— is in every case infinitely less than is supposed in
the classical image of the vital vortex. It is the
merit of physiologists, and particularly of Pfliiger and
Chauveau, to have worked for nearly forty years
to establish this truth. They have proved it, at
least as far as the muscular tissue is concerned.
Protoplasm, properly so-called, is only destroyed
as the organs of a steam engine are destroyed — its
tubes, its boiler, its furnace. And it matters little.
We know that such an engine uses much coal, and we
know very little of its machinery and its metallic
frame. And so it is with the cell, the living machine.
A very small portion of the food introduced will be
assimilated in the living substance. By far the
greater part of it is destined to be worked up by the
protoplasm and placed in reserve under the form of
glycogen, albumen, and fat, etc. — i.e., compounds
which are not the really living substance, the hereditary
protoplasm, but the products of its industry, just as
they are or may be the products of the industry of
the chemist working in his laboratory. They will be
expended for the purpose of furnishing the necessary
energy to the vital functional activity, muscular

NUTRITION. 231

contraction, secretion, heat, etc., just as coal is
expended to set the steam engine going. The proof
as far as the muscle is concerned does not stand
alone. There are other examples. In particular,
micrographic physiologists who have studied nervous
phenomena say that the anatomical elements of the
brain last indefinitely, and that they continue as they
are, without renewal from birth to death. The
permanence of the consciousness, be it said in
passing, is connected by them with the permanence
of the cerebral element (Marinesco).

Thus destruction is very restricted. There is only
a very slight disassimilation of the living matter,
properly so-called, in the course of the vital functional
activity. We may even go farther than this ex-
perimental fact. This is what Le Dantec has done
when he claims that there is even an assimilation, an
increase of the protoplasm. Strictly speaking, this
is possible, but there is no certain proof of it ; and in
any case we cannot agree with him when he affirms
that the increase is the direct result of the functional
activity and blends with it in one single, unique
operation. We must, on the contrary, agree with
Claude Bernard that it is only a consequence of it,
that it is produced in consequence of the existence of
a bond of correlation between organic destruction and
assimilating synthesis.

Why is there this bond ? That is easily under-
stood if we reflect that the assimilating synthesis, an
operation of endothermic, chemical complexity, natur-
ally requires an exothermic counterpart, the organic
destruction which will set free this necessary energy.

Formative Assimilation of Reserve-stuff. Format
tive Assimilation of Protoplasm.-^\t follows that

16

232 LIFE AND DEATH.

there are In nutritive assimilation itself two distinct
acts. The one consisting of the manufacture of
reserve-stuff is the more obvious but the less
specific ; the other, really essential, is assimilation
properly so-called, the reconstitution of the proto-
plasm. The former is indispensable to the pro-
duction of the most prominent acts of vitality —
movement, secretion, production of heat. If it is
suspended, functional activity is arrested. We get
apparent death, or latent life. But if the real assimi-
lation is arrested, we have real deatli.

According to this there would be a fundamental
distinction betyveen real and apparent death. The
former would be characterized by an arrest of the
protoplasmic assimilation which is externally indicated
by no sign. On the other hand, apparent death
would be characterized by the arrest of the formation
and destruction of reserve-stuff. It would be ex-
ternally manifested by two signs : — The suppression
of material exchanges with the medium (respiration,
alimentation) and the suppression of the functional
acts (production of movement, of heat, of electricity,
of glandular excretion).

Such would be the most expedient test for apparent
or real death. The question occurs in the case of
grains of corn in Egyptian tombs, and also of
hibernating animals and revlvlscent beings, and, in
general, in the case of what has been called the state
of latent life. But from the practical point of view
it is extremely difficult to apply this test and to
decide if the phenomena which are arrested in the
grain at maturity, in Leeuwenhoek's tardigrada,^

^ Bear-animalcules, Sloth-animalcules. An order of Arach-
nida. — Tr.

NUTRITION. 233

and in the dried-up AnguilluHdae^ of Baker and
Spallanzani, in the encysted colpoda^ that a drop of
warm water will revive, in the animals exposed by
E, Yung and Pictet to a cold of more than a
100" C. below zero, are due to the general arrest of
the two forms of assimilation, or to the arrest of the
manufacture and utilization of reserve-stuff alone, or
finally, to the arrest of protoplasmic assimilation
alone. The latter, which is already very restricted
in beings in a normal condition whose growth is
terminated, may fall to the lowest degree in the
being which, having no functional activity, is assimi-
lating nothing. So that, to cut the question short,
the experimenter who measures the value of the
exchanges between the being and the medium has
seldom to do more than decide between little and
nothing. Hence his perplexity. But if experiment
hesitates, theory affirms : it admits a priori that the
movement of protoplasmic assimilation, an essential
sign of vitality, is neither checked nor renewed, but
proceeds continuously.

Is Nutrition^ the Assimilating Synthesis, inter-
rupted?— Nevertheless, there are many reasons for
suspending all judgment as to this interpretatioh.
It is questioned by most biologists. According to
A. Gautier, the preserved grain of corn and the dried
up rotifera are not really alive ; they are like clocks
in working order, ready to tell the time, but awaiting
in absolute repose the first vibration which will set
them going. As for the grain, it is the air, heat, and

^ Minute thread worms, known as paste-eels and vinegar-
eels.— Tr.

"^ Genus of Infusoria. Colpodea cucullils is found in infusions
of hay — Tr.

234 LIFE AND DEATH.

moisture which supply the first impulse. In other
words, the organization proper to the manifestation of
life remains, but there is no life. The so-called
arrested life is not a life.

It must be said, however, that the majority of
physiologists refuse to accept this interpretation.
They believe in an attenuation of the nutritive
synthesis and not in its complete destruction. They
think that this total suppression would be contrary
to current ideas relative to the perpetuity of the
protoplasm and the limited duration of the living
element. The natural medium is variable, and even
the mineral cannot remain eternally fixed. Still less
is perennity a property of the living being. If
ordinary life is for each individual of limited duration,
the arrested life must also be of limited duration.
We cannot believe that after an indefinitely prolonged
sleep the grain of corn, or the paste-eel, or the
colpoda, emerging from their torpor can resume their
existence, like the Sleeping Beauty, at the point at
which it was interrupted, and thus pass with a bound,
as it were, through the centuries.

In fact the maintenanqe of the vitality of grains
of corn from the Egyptian tombs and their aptitude
to germinate after thousands of years are only fables
or the result of imposture. Maspero, in a letter
addressed to M. E. Griffon on the 15th July 1901,
has clearly summed up the situation by saying that
the grains of corn bought from the fellahs almost
always germinate, but that this is never the case with
those that the experimenter himself takes from the
tombs.

To sum up, we must use the same language of
nutrition and of life, of their uninterrupted progress,

NUTRITION. 235

of their continuity, of their permanence, of their
activity, and of their slackening. Living matter is
always growing, much or little, slowly or quickly,
in its reserve-stuff or in its protoplasm, for expenditure
or accumulation. This inevitability of growth defines
it, characterizes it, and sums up its activity. Develop-
ment and the evolution of growth are consequences or
aspects of nutrition.

BOOK IV.

THE LIFE OF MATTER.

Summary: Chap. I. Universal life — Opinions of philosophers
and poets — Continuity between brute and living bodies —
Origin of this principle. — Chap. II. Origin of brute matter
in living matter. — Chap. III. Organization and chemical
composition of brute and living bodies. — Chap. IV. Evolu-
tion and transformation of brute and living bodies. —
Chap. V. Possession of a specific form — Living bodies and
crystals — Cicatrization. — Chap. VI. Nutrition in the living
body and in the crystal. — Chap. VII. Generation in brute
and in living bodies — Spontaneous generation.

Apparent Differences between Living and Brute
Bodies. The Two Kingdoms. — It seems at first
impossible that there should be any essential
similarity between an inanimate object and a living
being. What resemblance can be discovered between
a stone, a lion, and an oak ? A comparison of the
inert and immovable pebble with the leaping animal,
and with the plant extending its foliage gives an
impression of vivid contrast. Between the organic
and the inorganic worlds there seems to be an abyss.
The first impressions we receive confirm this view ;
superficial investigation furnishes arguments for it.
There is thus aroused in the mind of the child, and
later in that of the man, a sharply marked distinction
between the natural objects of the mineral kingdom
on the one hand, and those of the two kingdoms of
living beings on the other.

236

THE LIFE OF MATTER. 237

But a more intimate knowledge daily tends to
throw doubt upon the rigour or the absolute character
of such a distinction. It shows that brute matter can
no longer be placed on one side and living beings on
the other. Scientists deliberately speak of "the life
of matter," which seems to the average man a con-
tradiction in terms. They discover in certain classes
of mineral bodies almost all the attributes of life.
They find in others fainter, but still recognizable
indications of an undeniable relationship.

We propose to pass in review these analogies and
resemblances, as has already been done in a fairly
complete manner by Leo Errera, C. E. Guillaume,
L. Bourdeau, Ed. Griffon, and others. We will con-
sider the fine researches of Rauber, of Ostwald,
and of Tammann upon crystals and crystalline germs
— researches which are merely a continuation of those
of Pasteur and of Gernez. These show that crystal-
line bodies are endowed with the principal attributes
of living beings — i.e., a rigorously defined form ; an
aptitude for acquiring it, and for re-establishing it by
repairing any mutilations that may be inflicted upon
it ; nutritive growth at the expense of the mother
liquor which constitutes its culture medium ; and,
finally — a still more incredible property — all the
characteristics of reproduction by generation. Other
curious facts observed by skilful physicists — W.
Roberts-Austen, W. Spring, Stead, Osmond, Guille-
min, Charpy, C. E. Guillaume — show that the immu-
tability even of bodies supposed to be the most rigid
of all, such as glass, the metals, steel, and brass, is
apparent rather than real. Beneath the surface of the
metal that seems to us inert there is a swarming
population of molecules, displacing each other, moving

238 LIFE AND DEATH.

about, and arranging thennselves so as to form definite
figures, and assuming forms adapted to the conditions
of the environment. Sometimes it is years before
they arrive at the state of ultimate and final equili-
brium— which is that of eternal rest.

However, in order to understand these facts and
their interpretations, it is necessary to pass in review
the fundamental characteristics of living beings. It
will be shown that these very characteristics are found
in inanimate matter.

CHAPTER I.

UNIVERSAL LIFE, OPINIONS OF PHILOSOPHERS
AND POETS.

§ I. Primitive beliefs; the ideas of poets. — § 2. Opinions of
philosophers — Transition from brute to living bodies — The
principle of continuity: continuity by transition : continuity
by summation — Ideas of philosophers as to sensibility and
consciousness in brute bodies — The general principle of
homogeneity — The principle of continuity as a consequence
of the principle of homogeneity.

§ I. Primitive Beliefs. Ideas of the Poets.

The teaching of science as to the analogies between
brute bodies and living bodies accords with the con-
ceptions of the philosophers and the fancies of the
poets. The ancients held that all bodies in nature
were the constituent parts of a universal organism,
the macrocosm, which they compared to the human
microcosm. They attributed to it a principle of
action, the psyche, analogous to the vital principle,
and this psyche directed phenomena; and also an
intelligent principle, the nous, analogous to the soul,
and the nous served for the comprehension of pheno-
mena. This universal life and this universal soul
played an important part in their metaphysical
systems,

239

240 LIFE AND DEATH.

It was the same with the poets. Their tendency
has always been to attribute h"fe to Nature, so as to
bring her into harmony with our thoughts and feel-
ings. They seek to discover the life or soul hidden
in the background of things.

" Hark to the voices. Nothing is silent.

Winds, waves, and flames, trees, reeds, and rocks
All live; all are instinct with soul."

After making proper allowance for emotional
exaggeration, ought we to consider these ideas as the
prophetic divination of a truth which science is only
just beginning to dimly perceive? By no means. As
Renan has said, this universal animism, instead of
being a product of refined reflection, is merely a
legacy from the most primitive of mental processes,
a residue of conceptions belonging to the childhood
of humanity. It recalls the time when men conceived
of external things only in terms of themselves; when
they pictured each object of nature as a living being.
Thus, they personified the sky, the earth, the sea, the.
mountains, the rivers, the fountains, and the fields.
They likened to animate voices the murmur of the
forest : —

". . . The oak chides and the birch
Is whispering. . . .
And the beech murmurs. . . .

The willow's shiver, soft and faint, sounds like a word.
The pine-tree utters mysterious moans."

For primitive man, as for the poet of all times,
everything is alive, and every sound is due to a being
with feelings similar to our own. The sighing of the
breeze, the moan of the wave upon the shore, the

UNIVERSAL LIFE. 24I

babbling of the brook, the roaring of the sea, and the
pealing of the thunder are nothing less than sad,
joyous, or angry living voices.

These impressions were embodied in ancient
mythology, the graceful beauty of which does not
conceal its inadequacy. Then they passed into
philosophy and approached the realm of science.
Thales believed that all bodies in nature were
animate and living. Origen considered the stars as
actual beings. Even Kepler hin>self attributed to the
celestial bodies an internal principle of action, which,
it may be said in passing, is contrary to the law of
the inertia of matter, which has been wrongly ascribed
to him instead of to Galileo, The terrestrial globe
was, according to him, a huge animal, sensitive to
astral influences, frightened at the approach of the
other planets, and manifesting its terror by tempests,
hurricanes, and earthquakes. The wonderful flux and
reflux of the ocean was its breathing. The earth had
its blood, its perspiration, its excretions; it also had
its foods, among which was the sea water which it
absorbs by numerous channels. It is only fair to add
that at the end of his life Kepler retracted these vague
dreams, ascribing them to the influence of J. C.
Scaliger. He explained that by the soul of the
celestial bodies he meant nothing more than their
motive force.

§ 2. Opinion of the Philosophers.

Transition from Brute to Living Bodies. — The
lowering of the barrier between brute bodies and
living bodies began with those philosophers who

242 LIFE AND DEATH.

introduced into the world the great principles of
continuity and evolution.

The Principle of Continuity. — First and foremost
we must mention Leibniz. According to the teaching
of that illustrious philosopher, as interpreted by M.
Fouillee, "there is no inorganic kingdom, only a great
organic kingdom, of which mineral, vegetable, and
animal forms are the various developments. . . .
Continuity exists everywhere throughout the world;
everywhere is life and organization. Nothing is
dead ; life is universal." It follows that there is no
interruption or break in the succession of natural
phenomena ; that everything is gradually developed ;
and finally, that the origin of the organic being must
be sought in the inorganic. Life, properly so called,
has not, in fact, always existed on the surface of the
globe. It appeared at a certain geological epoch, in
a purely inorganic medium, by reason of favourable
conditions. The doctrine of continuity compels us,
however, to admit that it pre-existed on the globe
under some rudimentary form.

The modern philosophers who are imbued with
these principles, MM. Fouillee, L. Bourdeau, and A.
Sabatier, express themselves in similar language.
"Dead matter and living matter are not two abso-
lutely different entities, but represent two forms of
the same matter, differing only in degree, sometimes
but slightly." When it is only a matter of degree, it
cannot be held that these views are opposed. In-
equalities must not be interpreted as contrary attri-
butes, as when the untrained mind considers heat
and cold as objective states, qualitatively opposed
to each other.

Continuity by Transition, — The argument which

UNIVERSAL LIFE. 243

leads us to remove the barrier between the two king-
doms, and to consider minerals as endowed with a
sort of rudimentary life, is the same as that which
compels us to admit that there is no fundamental
difference between natural phenomena. There are
transitions between what lives and what does not,
between the animate being and the brute body. And
in the same way there are transitions between what
thinks and what does not think, between what is
thought and what is not thought, between the con-
scious and the unconscious. This idea of insensible
transition, of a continuous path between apparent
antitheses, at first arouses an insuperable opposition
in minds not prepared for it by a long comparison of
facts. It is slowly realized, and finally is accepted by
those who, in the world of things, follow the infinity
of gradations presented by natural phenomena. The
principle of continuity comes at last to constitute, as
one may say, a mental habit. Thus the man of science
may be led, like the philosopher, to entertain the
idea of a .rudimentary form of life animating matter.
He may, like the philosopher, be guided by this idea ;
he may attribute a priori to brute matter all the really
essential qualities of living beings. But this must
be on the condition that, assuming these properties to
be common, he must afterwards demonstrate them by
means of observation and experiment He must show
that molecules and atoms, far from being inert and
dead masses, are in reality active elements, endowed
with a kind of inferior life, which is manifested by all
the transformations observed in brute matter, by
attractions and repulsions, by movements in response
to external stimuli, by variations of state and of
equilibrium; and finally, by the systematic methods

244 LIFE AND DEATH.

according to which these elements group themselves,
conforming to those definite types of structure by
means of which they produce different species of
chemical compounds.

Contimnty by Summation. —The idea of summation
leads by another path to the same result. It is
another form of the principle of continuity. A sum
total of effects, obscure and indistinct in themselves,
produces a phenomenon appreciable, perceptible, and
distinct, apparently, but not really, heterogeneous in
its components. The manifestations of atomic or
molecular activity thus become manifestations of vital
activity.

This is another consequence of the teaching of
Leibniz. For, according to his philosophical theory,
individual consciousness, like individual life, is the
collective expression of a multitude of elementary
lives or consciousnesses. These elements are in-
appreciable because of their low degree, and the real
phenomenon is found in the sum, or rather the
integral, of all these insensible effects. The ele-
mentary consciousnesses arc harmonized, unified,
integrated into a result that becomes manifest, just
as "the sounds of the waves, not one of which would
be heard if by itself, yet, when united together and
perceived at the same instant, become the resounding
voice of the ocean."

Ideas of the Philosophers as to Sensibility and Con-
sciousness in Brute Bodies. — The philosophers have
gone still further in the way of analogies; and have
recognized in the play of the forces of brute matter,
particularly in the play of chemical forces, a mere
rudiment of the appetitions and tendencies that regu-
late, as they believe, the functional activity of living

UNIVERSAL LIFE. _^ 245

beings — a trace, as it were, of their sensibility. To
them reactions of matter indicate the existence of a
kind of liedonic consciousness — i.e., a consciousness
reduced simply to a distinction between comfort and
discomfort, a desire for good and repulsion from evil,
which they suppose to be the universal principle of all
activity. This was the view held by Empedocles in
antiquity; it was that of Diderot, of Cabanis, and, in
general, of the modern materialistic school, eager to
find, even in the lowest representatives of the
inorganic world, the first traces of the vitality and
intellectual life which blossom out at the top of the
scale in the living world.

Similar ideas are clearly seen in the early history of
all natural sciences. It was this same principle of
appetition, or of love and of repulsion or hate that,
under the names of affinity, selection, and incom-
patibility, was thought to direct the transformations of
bodies when chemistry first began ; when Boerhaave,
for example, compared chemical combinations to
voluntary and conscious alliances, in which the
respective' elements, drawn together by sympathy,
contracted appropriate marriages.

General Principle of the Homogeneity of the Complex
and its Components. — The assimilation of brute bodies
to living bodies, and of the inorganic kingdom to the
organic, was, in the mind of these philosophers, the
natural consequence of positing a priori the principles
of continuity and evolution. There is, however, a
principle underlying these principles. This principle
is not expressed explicitly by the philosophers; it is
not formulated in precise terms, but is more or less
unconsciously implied ; it is everywhere applied. It,
however, may be clearly seen behind the apparatus of

246 LIFE AND DEATH.

philosophical argument. It is the assertion that no
arrangement or combination of elements can put
forth any new activity essentially different from the
activities of the elements of which it is composed.
Man is living clay, say Diderot and Cabanis ; and,
on the other hand, he is a thinking being. As it is
impossible to produce tJiat wJiidi thinks from that which
does not think, the clay must possess a rudiment of
thought. But is there not another alternative ? May
not the new phenomenon, thought, be the effect of
the arrangement of this clay? If we exclude this
alternative, we must then consider arrangement and
organization as incapable of producing in arranged
and organized matter a new property different from
that which it presented before such arrangement.
Living protoplasm, " says another, is merely an
assemblage of brute elements; "these brute elements
must therefore possess a rudiment of life." This is
the same implied supposition which we have just
considered ; if life is not the basis of each element, it
cannot result from their simple assemblage.

Man and animals are combinations of atoms, says
M. le Dantec. It is more natural to admit that
human consciousness is the result of the elementary
consciousness of the constituent atoms than to con-
sider it as resulting from construction by means
of elements with no consciousness. " Life," says
Haeckel, "is universal; we could not conceive of its
existence in certain aggregates of matter if it did not
belong to their constituent elements." Here the
postulate is almost expressed.

The argument is always the same ; even the same
words are used : the fundamental hypothesis is the
same ; only it remains more or less unexpressed,

UNIVERSAL LIFE. 247

more or less unperceived. It may be stated as
follows : — Arrangement, assemblage, construction, and
aggregation are powerless to bring to light in the
complex anything new and essentially heterogeneous
to what already exists in the elements. Reciprocally,
grouping reveals in a complex a property and
character which is the gradual development of an
analogous property and character in the elements.
It is in this sense that there exists a collective soul in
crowds, the psychology of which has been discussed
by M. G. Le Bon. In the same way, many sociolo-
gists; adopting the views advanced by P. de Lilienfeld
in 1865, attribute to nations a formal individuality,
after the type of that possessed by each of their
constituent members. M. Izolet considers society
as an organism, which he calls a " hyperzoan."
Herbert Spencer has developed the comparison of
the collective organism with the individual organism,
insisting on their resemblances and differences. Th.
Ribot has dwelt, in particular, on the resemblances.

The postulate that we have clearly stated here is
accepted by many as an axiom. But it is not an
axiom. When we say that there is nothing in the
complex that cannot be found in the parts, we think
we are expressing a self-evident truth ; but we are,
in fact, merely stating an hypothesis. It is assumed
that arrangement, aggregation, and complicated and
skilful grouping of elements can produce nothing
really new in the order of phenomena. And this is
an assertion that requires verification in each par-
ticular case.

The Principle of Continuity, a Consequence of the
Preceding. — Let us apply this principle to the beings
in nature. All. beings in nature are, according to

17

248 LIFE AND DEATH.

current ideas, arrangements, aggregates, or groupings
of the same universal matter, that is to say, of the
same simple chemical bodies. It results from the
preceding postulate that their activities can only differ
in degree and form, and not fundamentally. There
is no essential difference of nature between the
activities of various categories of beings, no hetero-
geneity, no discontinuity. We may pass from one to
another without coming to an hiatus or impassable
gulf. The law of continuity thus appears as a simple
consequence of the fundamental postulate. And so
it is with the law of evolution, for evolution is merely
continuity of action.

Such are the origins of the philosophical doctrine
which universalizes life and extends it to all bodies
in nature.

It may be remarked that this doctrine is not
confined to any particular school or sect. Leibniz
was by no means a materialist, and he endowed his
mundane elements, his monads, not only with a sort
of life, but even ivith a sort of soul. Father Bosco-
vitch, Jesuit as he was, and professor in the college of
Rome, did not deny to his indivisible points a kind of
inferior vitality. St. Thomas, too, the angelical
doctor, attributed, according to M. Gardair, to
inanimate substances a certain kind of activity,
inborn inclinations, and a real appetition towards
certain acts.

CHAPTER II.

ORIGIN OF BRUTE MATTER IN LIVING MATTER.

Spontaneous generation : an episode in the history of the
globe — Verification of the identity between brute and
living matter — Slow identification — Rapid identification
— Contrary opinion — Hypothesis of cosmozoa ; cosmic
panspermia — Hypothesis of pyrozoa.

There should be two ways of testing the doctrine of
the essential identity of brute and living matter —
one slow and more laborious, the other more rapid
and decisive.

Identification of the Two Matters, Brute and
Living. — The laborious method, which we will be
obliged to .follow, consists in the attentive examina-
tion of the various activities by which life is
manifested, and in finding more or less crude
equivalents for them in all brute beings, or in certain
of them.

Rapid Verification. Spontaneous Generation. — The
rapid and decisive method, which, unhappily, is
beyond our resources, would consist in showing un-
questionable, clearly marked life, the superior life,
arising from the kind of inferior life that is attributed
to matter in general. It would be necessary com-
pletely to construct in all its parts, by a suitable
combination of inorganic materials, a single living
being, even the humblest plant or the most rudi-

249

250 LIFE AND DEATH.

mentary animal. This would indeed be an irrefutable
proof that the germs of all vital activity are contained
in the molecular activity of brute bodies, and that
there is nothing essential to the latter that is not
found in the former.

Unhappily this demonstration cannot be given.
Science furnishes no example of it, and we are forced
to have recourse to the slow method.

The question here involved is that of spontaneous
generation. It is well known that the ancients
believed in spontaneous generation, even for animals
high in the scale of organization. According to
Van Helmont, mice could be born by some incom-
prehensible fermentation in dirty linen mixed with
wheat. Diodorus speaks of animal forms which were
seen to emerge, partly developed, from the mud of
the Nile. Aristotle believed in the spontaneous birth
of certain fishes. This belief, though rejected as to
the higher forms, was for a long time held with
regard to the lower forms of animals, and to insects —
such as the bees which the shepherd of Virgil saw
coming out from the flanks of the dead bullock —
flies engendered in putrefying meat, fruit worms and
intestinal worms ; finally, with regard to infusoria
and the most rudimentary vegetables. The hypo-
thesis of the spontaneous generation of the living
being at the expense of the materials of the ambient
medium has been successively driven from one
classificatory group to another. The history of the
sciences of observation is also a history of the con-
futation of this theory. Pasteur gave it the finishing
stroke, when he showed that the simplest micro-
organisms obeyed the general law which declares
that the living being is formed only hy filiation — that

ORIGIN OF BRUTE MATTER. '• 25 1

is to say, by the intervention of a pre-existing living
organism.

Spontaneous Generation an Episode in the History
of the Globe. — Though we have been unable to effect
spontaneous generation up to the present, it has been
referred by Haeckel to a more or less distant past, to
the time when the cooling of the globe, the solidifica-
tion of its crust, and the condensation of aqueous
vapour upon its surface created conditions compatible
with the existence of living beings similar to those
with which we are acquainted. Lord Kelvin has
fixed these geological events as occurring from twenty
to forty million years ago. Then circumstances
became propitious for the appearance of the first
organisms, whence were successively derived those
which now people the earth and the waters.

Circumstances favourable to the appearance of the
first beings apparently occurred only in a far distant
past ; but most physiologists admit that if we knew
exactly these circumstances, and could reproduce
them, we might also expect to produce their effect —
namely, the creation of a living being, formed in all
its parts, developed from the inorganic kingdom.
To all those who held this view the impotence of
experiment at the present time is purely temporary.
It is comparable to that of primitive men before the
time of Prometheus ; they, not knowing how to
produce fire, could only get it by transmitting it
from one to another. It is due to the inadequacy
of our knowledge and the weakness of our means ; it
does not contradict the possibility of the fact.

Contrary Opinion. Life did not Originate on our
Globe. — But all biologists do not share this opinion.
Some, and not the least eminent, hold it to be an

252 LIFE AND DEATH.

established fact that it is impossible for life to arise
from a concurrence of inorganic materials and forces.
This was the opinion of Ferdinand Cohn, the great
botanist ; of H. Richter, the Saxon physician, and of
W. Preyer, a physiologist well known from his
remarkable researches in biological chemistry.
According to these scientists, life on the surface of
the globe cannot have appeared as a result of the
reactions of brute matter and the forces that continue
to control it.

According to F. Cohn and II. Richter, life had no
beginning on our planet. It was transported to the
earth from another world, from the cosmic medium,
under the form of cosmic germs, or cosmozoa, more
or less comparable to the living cells with which we
are acquainted. They may have made the journey
either enclosed in meteorites, or floating in space in
the form of cosmic dust. The theory in question
has been presented in two forms : — The Hypothesis of
Meteoric Cosinozoa, by a French writer, the Count
de Salles-Guyon ; and that of cosmic panspermia
brought forward in 1865 and 1872 by F. Cohn and
H. Richter.

Hypothesis of the Cosiiiosoa. — The hypothesis of
the cosmozoa, living particles, protoplasmic germs
emanating from other worlds and reaching the earth
by means of aerolites, is not so destitute of probability
as one might at first suppose. Lord Kelvin and
Helmholtz gave it the support of their high authority.
Spectrum analysis shows in cometary nebulae the
four or five lines characteristic of hydro-carbons.
Cosmic matter, therefore, contains compounds of
carbon, substances that are especially typical of
organic chemistry. Besides, carbon and a sort of

ORIGIN OF BRUTE MATTER. . 253

humus have been found in several meteorites. To
the objection that these aerolites are heated while
passing through our atmosphere, Helmholtz replies
that this elevation of temperature may be quite
superficial and may allow micro-organisms to subsist
in their interior. But other objections retain their
force : — First, that of M. Verworn, who considers the
hypothesis of cosmic germs as inconsistent with the
laws of evolution ; and that of L. Errera, who denies
that the conditions necessary for life exist in inter-
planetary bodies.

Hypothesis of Cosviic Panspermia. — Du Bois-
Reymond has given the name of cosmic panspermia
to a theory very similar to the preceding, formulated
by F. Cohn in 1872. The first living germs arrived
en our globe mingled with the cosmic dust that
floats in space and falls slowly to the surface of the
earth. L. Errera observes that if they escape by
this gentle fall the dangerous heating of meteorites,
they still remain exposed to the action of the photic
rays, which is generally destructive to germs.

Hypothesis of Pyrozoa. — W. Preyer declined to
accept this cosmic transmigration of the simplest
living beings, nor would he allow the intervention of
other worlds into the history of our own. Life,
according to him, must have existed from all time,
even when the globe was an incandescent mass.
But it was not the same life as at present. Vitality
must have undergone many profound changes in the
course of ages. The pyrozoa, the first living beings,
vulcanians, were very different from the beings of
the present day that are destroyed by a slight
elevation of temperature. No doubt this theory of
pyrozoa, proposed by W. Preyer in 1872, seems

254 LIFE AND DEATH.

quite chimerical, and akin to Kepler's dreamy visions.
But in a certain way it accords with contemporary
ideas concerning the life of matter. It is related to
them by the evolution which it implies in the materials
of the terrestrial globe.

According to Preyer, primitive life existed in fire.
Being igneous masses in fusion, the pyrozoa lived
after their own manner; their vitality, slowly modified,
assumed the form which it presents to-day. Yet, in
this profound transformation their number has not
varied, and the total quantity of life in the universe
has remained unchanged.

Here we recognize the ideas of Buffon. These
cosmozoa, these pyrozoa, have a singular resemblance
to the organic molecules of "live matter" of the
illustrious naturalist — distributed everywhere, in-
destructible, and forming living structures by their
concentration.

But we must leave these scientific or philosophical
theories, and come to arguments based upon facts.

It is in a spirit quite different from that of the
poets, the metaphysicians, and the more or less
philosophical scientists that the science of our days
looks at the more or less obscure vitality of inanimate
bodies. It claims that we may recognize in them,
in a more or less rudimentary state, the action
of the factors which intervene in the case of living
beings, the manifestation of the same fundamental
properties.

CHAPTER III.

ORGANIZATION AND CHEMICAL COMPOSITION OF
LIVING AND BRUTE MATTER.

Laws of the organization and of the chemical composition of
living beings — Relative value of these laws; vital pheno-
mena in crushed protoplasm — Vital phenomena in brute
bodies.

Eniuneration of the Principal Characters of Living
Beings. — The programme which we have just sketched
compels us to look in the brute being for the pro-
perties of living beings. What, then, are, in fact, the
characteristics of an authentic, complete, living being?
What are its fundamental properties ? We have
enumerated them above as follows: — A certain
chemical composition, which is that of living matter;
a structure or organization ; a specific form ; an
evolution which has a duration, that of life, and an
end, death ; a property of growth or nutrition ; a
property of reproduction. Which of these characters
counts for most in the definition of life ? Are they
all equally necessary ? If some of them were wanting,
would that justify the transference of a being, who
might possess the rest, from the animate world to
that of minerals ? This is precisely the question that
is under consideration.

Organization and Chemical Composition of Living
Beings. — All that we know concerning the constitution

255

256 LIFE AND DEATH.

of living matter and its organization is summed up in
the laws of the chemical unity and the morphological
unity of living beings (v. Book III.), These laws seem
to be a legitimate generalization from all the facts
observed. The first states that the phenomena of
life are manifested only in and through living matter,
protoplasm — i.c^ in and through a substance which
has a certain chemical and physical composition.
Chemically it is a proteid complexus with a hexonic
nucleus. Physically it shows a frothy structure
analogous to that resulting from the mixture of two
granular, immiscible liquids, of different viscosities.
The second law states that the phenomena of life
can only be maintained in a protoplasm which has
the organization of the complete cell, with its cellular
body and nucleus.

Relative Value of these Laws. Exceptions. — What
is the signification of these laws of the chemical
composition and organization of living beings?
Evidently that life in all its plenitude can only exist
and be perpetuated under their protection. If these
laws were absolute, if it were true that no life were
possible but in and through albuminous protoplasm,
but in and through the cell, the problem of "the life
of matter " would be decided in the negative.

May it not happen, however, that fragmentary and
incomplete vital manifestations, progressive traces
of a true life, may occur under different conditions;
for example, in matter which is not protoplasm, and
in a body which has a structure differing from that
of a cell — that is to say, in a being which would be
neither animal nor plant ? We must seek the answer
to this question by an appeal to experiment.

Without leaving the animal and vegetable king-

ORGANIZATION AND CHEMICAL COMPOSITION- 257

doms — i.e., real living beings — we already see less
rigour in the laws governing chemical constitution
and cellular organization.

Experiments in merotomy — i.e., in amputation —
carried out on the nervous element by Waller, on
infusoria by Brandt, Gruber, Balbiani, Nussbaum,
and Verworn, show us the necessity of the presence
of the cellular body and the nucleus — i.e., of the in-
tegrity of the cell. But they also teach us that when
that integrity no longer exists death .does not imme-
diately follow, A part of the vital functions continues
to be performed in denucleated protoplasm, in a cell
which is mutilated and incomplete.

Vital Phenomena in CrusJied Protoplasm. — It is
true also that grinding and crushing suppress the
greater part of the functions of the cell. But tests
with pulps of various organs and with those of certain
yeasts also show that protoplasm, even though ground
and disorganized, cannot be considered as inert, and
that it still exhibits many of its characteristic pheno-
mena ; for example, the production of diastases, the
specific agents of vital chemistry. Finally, while we
do not know enough about the actions of which the
secondary elements of protoplasm — its granulations,
its filaments — are capable, which this or that method
of destruction may bring to light, at least we know
that actions of this kind exist.

To sum up, we are far from being able to deny that
rudimentary, isolated vital acts may be produced by
the various bodies that result from the dismember-
ment of protoplasm. The integrity of the cellular
organization, even the integrity of protoplasm itself,
are therefore not indispensable for these partial
manifestations of vitalftv.

258 LIFE AND DEATH.

Besides, biologists admit that there exist with-
in the protoplasm aliquot parts, elements of an
inferior order, which possess special activities.
These secondary elements must have the principle
of their activity within themselves. Such are the
biophors to which Weismann attributes the vital
functions of the cell, nutrition, growth, and multipli-
cation. If there are biophors within the cell, we
may imagine them outside the cell, and since they
carry within themselves the principle of their activity
they may exercise it in an independent manner.
Unhappily the biophors, and other constituent ele-
ments of that kind, are purely hypothetical. They
are like Darwin's gemmules, Altmann's bioblasts, and
the pangens of De Vries. They have no relation to
facts of observation and to real existence.

Vital Phenomena in Brute Bodies. — There is no
doubt that certain phenomena of vitality may occur
outside of the cellular atmosphere. And carrying
this further, we may admit that they may be pro-
duced in certain slightly organized bodies (crushed
cells), and then in certain unorganized bodies in
certain brute beings. In every case it is certain that
effects are produced at any rate similar to those which
are characteristic of living matter. It is for observation
and experiment to decide as to the degree of similarity,
and their verdict is that the similarity is complete.
The crystals and the crystalline germs studied by
Ostwald and Tammann are the seat of phenomena
which are quite comparable to those of vitality.

CHAPTER IV.

EVOLUTION AND MUTABILITY OF LIVING MATTER
AND BRUTE MATTER.

Supposed immobility of brute bodies — Mobility and mutability
of the sidereal world. — § i. The movement of particles and
molecules in brute bodies — The internal movements of
brute bodies — Kinetic conception of molecular motion —
Reality of the motion of particles — Comparison of the
activity of particles with vital activity. — § 2. Brownian
movement — Its existence — Its character — Its independence
of the nature of the bodies and of the nature of the environ-
ment— Its indefinite duration — Its independence of external
conditions — The Brownian movement must be the first
stage of molecular motion. — § 3. Motion of particles —
Migration of material particles — Migration under the
action of weight ; of diffusion; of electrolysis; of mechanical
pressure. — § 4. Internal activity of alloys — Their structure —
Changes produced by deforming agencies — Slow return to
equilibrium— Residual effect — Effect of annealing; effect
of stretching — Nickel steel — Colour photography — Con-
clusion— Relations of the environment to the living or brute
matter.

One of the most remarkable characteristics of a Hving
being is its evolution. It undergoes a continuous
change. It starts from something very small ; it
assumes a configuration and grows ; in most cases
it declines and disappears, having followed a course
which may be predicted — a sort of ideal trajectory.

Supposed Immobility of Brute Bodies. — It may be
asked whether this evolution, this directed mobility,

259

26o LIFE AND DEATH.

is SO exclusively a feature of the living being as it
appears, and if many brute bodies do not present
something analogous to it. We may answer in no
uncertain tones.

Bichat was wrong when he contrasted in this
respect brute bodies with living bodies. Vital
properties, he said, are temporary; it is their nature
to be exhausted ; in time they are used up in the
same body. Physical properties, on the contrary, are
eternal. Brute bodies have neither a beginning nor
an inevitable end, neither age, nor evolution; they
remain as immutable as death, of which they are the
image.

Mobility and Mutability of the Sidereal World. —
This is not true, in the first place, of the sidereal
bodies. The ancients held the sidereal world to be
immutable and incorruptible. The doctrine of the
incorruptibility of the heavens prevailed up to the
seventeenth century. The observers who at that
epoch directed towards the heavens the first telescope,
which Galileo had just invented, were struck with
astonishment at discovering a change in that celestial
firmament which they had hitherto believed incor-
ruptible, and at perceiving a new star that appeared
in the constellation Ophiuchus. Such changes no
longer surprise us. The cosmogonic system of
Laplace has become familiar to all cultivated minds,
and every one is accustomed to the idea of the con-
tinual mobility and evolution of the celestial world.
"The stars have not always existed," writes M. Faye;
" they have had a period of formation ; they will
likewise have a period of decline, followed by final
extinction."

Thus all the bodies of inanimate nature are not

EVOLUTION AND MUTABILITY OF. MATTEli. 261

eternal and immutable ; the celestial bodies are
eminently susceptible of evolution, slow indeed with
that we observe on the surface of our globe; but this
disproportion, corresponding to the immensity of
time and of cosmic spaces as compared with terres-
trial measurements, should not mislead us as to the
fundamental analogy of the phenomena.

§ I. The Movement of Particles and Mole-
cules IN Brute Bodies.

It is not only in celestial spaces that we must
search for that mobility of brute matter which imitates
the mobility of living matter. In order to find it we
have only to look about us, or to inquire from
physicists and chemists.

As far as geologists are concerned, M. le Dantec
tells us somewhere of one who divided minerals into
living rocks — rocks capable of change of structure, of
evolution under the influence of atmospheric causes;
and dead rocks — rocks which, like clay, have found at
the end of all their changes a final state of repose.
Jerome Cardan, a celebrated scientist of the sixteenth
century, at once mathematician, naturalist, and
physician, declared not only that stones live, but
that they suffer from disease, grow old, and die.
The jewellers of*the present day use similar language
of certain precious stones; the torquoise, for example.

The alchemists carried these ideas to an extreme.
It is not necessary here to recall the past, to evoke
the hermetic beliefs and the dreams of the alchemists,
who held that the different kinds of matter lived,
developed, and were transmuted into each other.

262 LIFE AND DEATH.

I refer to precise and recent data, established by
the most expert investigators, and related by one of
them, Charles Edward Guillaume, some years ago,
before the Soa'tft^ helv^tique des Sciences naturellcs.
These data show that determinate forms of matter
may live and die, in the sense that they may be
slowly and continuously modified, always in the same
direction, until they have attained an ultimate and
definitive state of eternal repose.

The Internal Movements of Bodies. — Swift's reply to
an idle fellow who spoke slightingly of work is well
known. " In England," said the author of Gulliver's
Travels, " men work, women work, horses work,
oxen work, water works, fire works, and beer works;
it is only the pig who does nothing at all; he must,
therefore, be the only gentleman in England." We
know very well that English gentlemen also work.
Indeed, everybody and everything works. And the
great wit was nearer right than he supposed in com-
paring men and things in this respect. Everything
is at work ; everything in nature strives and toils, at
every stage, in every degree. Immobility and repose
in the case of natural things are usually deceptive;
the seeming quietude of matter is caused by our
inability to appreciate its internal movements. Be-
cause of their minuteness we do not perceive the
swarming particles that compose it, and which, under
the impassible surface of the bodies, oscillate, displace
each other, move to and fro, and group themselves
into forms and positions adapted to the conditions
of the environment. In comparison with these
microscopic elements we are like Swift's giant among
the Lilliputians; and this is far from being a suffi-
ciently forcible comparison.

EVOLUTION AND MUTABILITY OF -MATTER; 263

Kinetic Conception of Molecular Motion. — The idea
of this peculiar form of motion is by no means new to
us. We were famih'arized with it in scientific theories
during our school days. The atomic theory teaches
us that matter behaves, from a chemical point of
view, as if it were divided into molecules and atoms.
The kinetic theory explains the constitution of gases
and the effects of heat by supposing that these
particles are endowed with movements of rotation
and displacement. The wave theory explains photic
phenomena by supposing peculiar vibratory move-
ments in a special medium — the ether. But these
are merely hypotheses which are not at all necessary;
they are the images of things, not the things them-
selves.

Reality of the Motion of Particles. — Here there is
no question of hypotheses. This internal agitation,
this interior labour, this incessant activity of matter
are positive facts, an objective reality. It is true that
when the chemical or mechanical equilibrium of
bodies is disturbed it is only restored more or less
slowly. Sometimes days and years are required
before it is regained. Scarcely do they attain this
relative repose when they are again disturbed, for the
environment itself is not fixed ; it experiences varia-
tions which react in their turn upon the body under
consideration ; and it is only at the end of these
variations, at the end of their respective periods, that
they will attain together, in a universal uniformity, an
eternal repose.

We shall see that metallic alloys undergo con-
tinual physical and chemical changes. They are
always seeking a more or less elusive equilibrium.
Physicists in modern times have given their attention

18

264 LIFE AND DEATH.

to this internal activity of material bodies, to the
pursuit of stability. Wiedemann, Warburg, Tomlin-
son, MM. Duguet, Brillouin, Duhem, and Bouasse
have revived the old experimental researches of
Coulomb and Wertheim on the elasticity of bodies,
the effects of pressures and thrusts, the hammering,
tempering, and annealing of metals.

The internal activity manifested under these cir-
cumstances presents quite remarkable characteristics
which cannot but be compared to the analogous
phenomena presented by living bodies. Thus have
arisen even in physics, a figurative terminology, and
metaphorical expressions borrowed from biology.

Comparison of the Activity of Paj-ticles with Vital
Activity. — Since Lord Kelvin first spoke of the fatigue
of metals, or the fatigue of elasticity, Bose has
shown in these same bodies the fatigue of electrical
contact. The term accommodation has been employed
in the study of torsion, and according to Tomlinson
for the very phenomena which are the inverse of
those of fatigue. The phenomena presented by glass
when acted on by an external force which slowly
bends it, have been called facts of adaptation. The
manner in which a bar of steel resists wire-drawing
has been compared to defensive processes against
threatened rupture. And M. C. E. Guillaume speaks
somewhere of " the heroic resistance of the bar of
nickel-steel." The term "defence" has also been
applied to the behaviour of chloride or iodide of
silver when exposed to light.

There has been no hesitation in using the term
" memory " concurrently with that of hysteresis to
designate the behaviour of bodies acted on by
magnetism or by certain mechanical forces. It ii

EVOLUTION AND MUTABILITY OF MATTER^ 265

true that M. H. Bouasse protests in the name of the
physico-mathematicians against the employment of
these figurative expressions. But has he not himself
written "a twisted wire is a wound-up watch," and
elsewhere, " the properties of bodies depend at every
moment upon all anterior modifications "? Does not
this imply that they retain in some manner the
impression of their past evolution ? Powerful de-
formative agencies leave a trace of their action ; they
modify the body's condition of molecular aggregation,
and some physicists go so far as to say that they even
modify its chemical constitution. With the exception
of M. Duhem, the disciples of the mechanical school
who have studied elasticity admit that the effect of an
external force upon a body depends upon the forces
which have been previously acting on it, and not
merely upon those which are acting on it at the
present moment. Its present state cannot be antici-
pated, it is the recapitulation of preceding states.
The effect of a torsional force upon a new wire will
be different from that of the same force upon a wire
previously subjected to torsions and detorsions. It
was with reference to actions of this kind that
Boltzmann, in 1876, declared that "a wire that has
been twisted or drawn out remembers for a certain
time the deformations which it has undergone."
This memory is obliterated and disappears after a
certain definite period. Here then, in a problem of
static equilibrium, we find introduced an unexpected
factor — time.

To sum up, it is the physicists themselves who
have indicated the correspondence between the con-
dition of existence in many brute bodies and that in
many living bodies. It cannot be expected that

266 LIFE AND DEATH.

these analogies will in any way serve as explanations.
We should rather seek to derive the vital from the
physical phenomenon. This is the sole ambition of
the physiologist. To derive the physical from the
vital phenomenon would be unreasonable. We do
not attempt to do this here. It is nevertheless true
that analogies are of service, were it only to shake the
support which, from the time of Aristotle, has been
accorded to the division of the bodies of nature into
psucJiia and apsucJiia — i.e., into living and brute
bodies.

§ 2. The Brownian Movement.

The Existence of the Brownian Movement. — The
simplest way of judging of the working activity of
matter is to observe it when the liberty of the
particles is not interfered with by the action of the
neighbouring particles. We approximate to this
condition when we watch, through the microscope,
grains of dust suspended in a liquid, or globules of
oil suspended in water. Now what we see is well
known to all microscopists. If the granulations are
sufficiently small, they seem to be never at rest.
They are animated by a kind of incessant tremor ;
we see the phenomena called the "Brownian move-
ment." This movement has struck all observers since
the invention of the magnifying glass or simple
microscope. But the English botanist, Brown, in
1827, made it the object of special research and gave
it his name. The exact explanation of it remained
for a long time obscure. It was given in 1894 by
M. Gouy, the learned physicist of the Faculty of
Lyons.

EVOLUTION AND MUTABILITY OF 'MATTER': 267

The observer who for the first time looks through
the microscope at a drop of water from the river, from
the sea, or from any ordinary source — that is to say,
water not specially purified — is struck with surprise
and admiration at the motion revealed to him.
Infusoria, microscopic articulata, and various micro-
organisms people the microscopic field, and animate
it by their movements ; but at the same time all sorts
of particles are also agitated, particles which cannot
be considered as living beings, and which are, in fact,
nothing but organic detritus, mineral dust, and debris
of every description. Very often the singular move-
ments of these granulations, which simulate up to a
certain point those of living beings, have perplexed
the observer or led him to erroneous conclusions, and
the bodies have been taken for animalcules or for
bacteria.

Characters of this Movement. — But it is as a rule
quite easy to avoid this confusion. The Brownian
movement is a kind of oscillation, a stationary,
dancing to-and-fro movement. It is a Saint Vitus's
dance on one and the same spot, and is thus dis-
tinguished from the movements of displacement
customary with animate beings. Each particle has
its own special dance. Each one acts on its own
account, independently of its neighbour. There is,
however, in the execution of these individual oscilla-
tions a kind of common and regular character which
arises from the fact that their amplitudes differ
little from each other. The largest particles are
the slowest ; when above four thousandths of a
millimetre in diameter, they almost cease to be
mobile. The smallest are the most active. When so
small as to be barely visible in the microscope, the

268 LIFE AND DEATH. '

movement is extremely rapid, and can only occasion-
ally be perceived. It is probable that it would be
still more accelerated in smaller objects; but the latter
will always escape our observation.

Its Independence of the Nature of the Bodies and of the
Environment. — M. Gouy remarked that the move-
ment depends neither on the nature nor on the form
of the particles. Even the nature of the liquid has
but little effect. Its degree of viscosity alone comes
into play. The movements are, indeed, more lively
in alcohol or ether, which are very mobile liquids ;
they are slow in sulphuric acid and in glycerine. In
water, a grain one two-thousandth of a millimetre in
diameter traverses, in a second, ten or twelve times its
own length.

The fact that the Brownian movement is seen in
liquors which have been boiled, in acids and in
concentrated alkalies, in toxic solutions of all degrees
of temperature, shows conclusively that the pheno-
menon has no vital significance ; that it is in no way
connected with vital activity so called.

Its Indefinite Duration. — The most remarkable char-
acter of this phenomenon is its permanence, its
indefinite duration. The movement never ceases,
the particles never attain repose and equilibrium.
Granitic rocks contain quartz crystals which, at the
moment of their formation, include within a closed
cavity a drop of water containing a bubble of gas.
These bubbles, contemporary with the Plutonian age
of the globe, have never since their formation ceased
to manifest the Brownian movement.

Its Independence of External Conditions. — What is
the cause of this eternal oscillation ? Is it a tremor
of the earth ? No ! M. Gouy saw the Brownian

EVOLUTION AND MUTABILITY OF 'MATTER; 269

movement far away from cities, where the mercurial
mirror of a seismoscope showed no subterranean
vibration. It does not increase when the vibrations
occur and become quite appreciable. Neither is it
changed by variation in light, magnetism, or electric
influences ; in a word, by any external occurrences.
The result of observation is to place before us the
paradox of a phenomenon which is kept up and
indefinitely perpetuated in the interior of a body
without known external cause.

The Broivnian Movement must be tJie First Stage of
Molecular Motion. — When we take in our hands a
sheet of quartz containing a gaseous inclusion, we
seem to be holding a perfectly inert object. When
we have placed it upon the stage of the microscope,
and have seen the agitation of the bubble, we are
convinced that this seeming inertia is merely an
illusion.

Repose exists only because of our limited vision.
We see the objects as we see from afar a crowd of
people. We perceive them only as a whole, without
being able to discern the individuals or their move-
ments. A visible object is, in the same way, a mass
of particles. It is a molecular crowd. It gives us
the impression of aji indivisible mass, of a block in
repose.

But as soon as the lens brings us near to this
crowd, as soon as the microscope enlarges for us the
minute elements of the brute body, then they appear
to us, and we perceive the continual agitation of those
elements which are less than four thousandths of a
millimetre in diameter. The smaller the particles
under consideration, the more lively are their move-
ments. From this we infer that if we could perceive

270 LIFE AND DEATH.

molecules, whose probable dimensions are about one
thousand times less, their probable velocity would be,
as required by the kinetic theory, some hundreds of
metres per second. In the case of objects we can
only just see, the Brownian velocity is only a few
thousandths of a millimetre per second. No doubt,
concludes M. Gouy, the particles that show this
velocity are really enormous when compared with
true molecules. From this point of view the
Brownian movement is but the first degree, and a
magnified picture of the molecular vibrations assumed
in the kinetic theory.

§ 3. The Internal Activity of Bodies.

Migration of Material Particles. — In the Brownian
movement we take into account only very small,
isolated masses, small free fragments — i.e., material
particles which are not hampered by their relations to
neighbouring particles. Any one but a physicist
might believe that in true solids endowed with
cohesion and tenacity, in which the molecules were
bound one to the other, in which form and volume
are fixed, there could be no longer movements or
changes. This is a mistake. Physics teaches us the
contrary, and, in late years especially, has furnished
us characteristic examples. There are real migrations
of material particles throughout solid bodies — migra-
tions of considerable extent. They are accomplished
through the agency of diverse forces acting externally
— pressures, thrusts, torsions; sometimes under the
action of light, sometimes under the action of elec-
tricity, sometimes under the influence of forces of

EVOLUTION AND MUTABILITY OF -MATTER/ 271

diffusion. The microscopic observation of alloys by
H. and A. Lechatelier, J. Hopkinson, Osmond, Charpy,
J. R. Benoit; researches into their physical and
chemical properties by Calvert, Matthiessen, Riche,
Roberts Austen, Lodge, Laurie, and C E. Guillaume;
experiments on the electrolysis of glass, and the
curious results of Bose upon electrical contact of
metals, show in a striking manner the chemical and
kinetic evolutions which occur in the interior of
bodies.

Migration under the Action of Weight. — An ex-
periment by Obermeyer, dating from 1877, furnishes
a good example of the motions of solid bodies
through a hardened viscid mass, taking place under
the influence of weight. The black wax that
shoemakers and boatbuilders use, is a kind of resin
extracted from the pine and other resinous trees,
melted in water, and separated from the more fluid
part which rises from it. Its colour is due to the
lampblack produced by the combustion of straw and
fragments of bark. At an ordinary temperature it is
a mass so hard that it cannot always be easily
scratched by the finger-nail; but if it is left to itself
in a receptacle, it finally yields, spreads out as if it
were a liquid, and conforms to the shape of the vessel.
Suppose we place within a cavity hollowed out of a
piece of wood a portion of this substance, and keep it
there by means of a few pebbles, having previously
placed at the bottom of the cavity a few fragments of
some light substance, such as cork. The piece of wax
is thus between a light body below and a heavy body
above. If we wait a few days, this order is reversed
— the wax has filled the cavity by conforming to it;
the cork has passed through the wajc and appears on

272 LIFE AND DEATH.

the surface, while the stones are at the bottom. We
have here the celebrated experiment of the flask with
the three elements, in which are seen the liquids
mercury, oil, and water superposed in the order of
their density, but in this case demonstrated with
solid bodies.

Influence of Diffusion. — Diffusion, which dissemin-
ates liquids throughout each other, may also cause
solids to pass through other solids. Of this W.
Roberts Austen gave a convincing proof. This in-
genious physicist placed a little cylinder of lead upon
a disc of gold, and kept the whole at the temperature
of boiling water. At this temperature both metals
are perfectly solid, for the melting point of gold is
1,200° C, and of lead is 330°. Still, after this contact
has been prolonged for a month and a half, analysis
shows that the gold has become diffused through the
top of the cylinder of lead.

Influence of Electrolysis. — Electrolysis offers another
no less remarkable means of transportation. By its
means we may force metals, such as sodium or lithium,
through glass walls. The experiment may be per-
formed as indicated by M. Charles Guillaume. A
glass bulb containing mercury is placed in a bath of
sodium amalgam, and a current is then made to pass
from within outward. After some time it can be
shown that the metal has penetrated the wall of the
bulb, and has become dissolved within it.

Influence of Mechanical Pressure. — Mechanical pres-
sure is also capable of causing one metal to pass into
another. We need not recall the well-known experi-
ment of Cailletet, who, by employing considerable
pressure, caused mercury to sweat through a block of
iron, In a more simple manner W. Spring showed

EVOLUTION AND MUTABILITY OF .MATTER., 273

that a disc of copper could be welded to a disc of tin
by pressing them strongly one against the other. Up
to a certain distance from the surfaces of contact
a real alloy is formed; a layer of bronze of a certain
thickness unites the two metals, and this could not
take place did not the particles of both metals
mutually interpenetrate.

§ 4. Internal Activity of Alloys.

Structure of Alloys. — Metallic alloys have a re-
markable structure, which is essentially mobile, and
which we have only now begun to understand by the
aid of the microscope. Microscopical examination
justifies to a certain degree Coulomb's conjecture.
That illustrious physicist explained the physical pro-
perties of metals by imagining them to be formed of
two kinds of elements — integral particles, to which the
metal owes its elastic properties, and a cement which
binds the particles, and to which it owes its coherence.
M. Brillouin has also taken up this hypothesis of
duality of structure. The metal is supposed to be
formed of very small, isolated, crystalline grains,
embedded in an almost continuous network of viscous
matter. A more or less compact mass surrounding
more or less distinct crystals is the conception which
may be formed of an alloy, '

Changes of Structure produced by Deforming
Agencies. — It has been shown that profound changes
of crystalline structure can be produced by various
mechanical means, such as hammering, and the
stretching of metallic bars carried to the point of
rupture. Some of these changes are very slow, and
it is only after months and years that they are com-

274 LIFE AND DEATH.

pletcd, and the metal attains the definite equilibrium
corresponding to the conditions to which it is exposed.
Though there may be discussions concerning the
extent of the transformations to which it is subjected,
though some believe they affect the chemical con-
dition of the alloy, while others limit its power to
physical effects, it is nevertheless true — and this
brings us back to our subject — that the mass of these
metals is at work, and that it only slowly attains the
phase of complete repose,

TJie Slozu Re-establishment of Equilibruun. Re-
sidual Effect. — These operations by which the physical
characters of metals are changed, and by which they
are adapted to a variety of industrial needs — com-
pression, hammering, rolling, stretching, and torsion —
have an immediate, very apparent effect; but they
have also a consecutive effect, slowly produced, much
less marked and less evident. This is the "residual
effect," or " Nachwirkung" of the Germans. It is not
without importance, even in practical applications.

Heat also creates a kind of forced egicilibriiim.
This becomes but slowly modified, so that a body
may remain for a long time in a state which is, how-
ever, not the most stable for the conditions under
which it is considered. The number of these bodies
not in equilibrium is as great as that of the substances
which have been exposed to fusion. All the Plutonic
rocks are in this condition. Glass presents a con-
dition of the same kind. Thermometers placed in
melting ice do not always mark the zero Centigrade.
This displacement of the zero point falsifies all
records if care is not taken to correct it. The
correction usually requires prolonged observation.
The theory of the displacement of the therrnometric

EVOLUTION AND MUTABILITY OF MATTER.. 275

zero is not entirely established ; but we may suppose,
with the author of the Traitc de Tlicrnioinctrie, that in
glass, as in alloys, are to be found compounds which
vary according to the temperature. At each tem-
perature glass tends to assume a determinate com-
position and a corresponding state of equilibrium ;
but the previous temperature to which it has been
subjected clearly has an influence on the rapidity
with which it attains its state of repose. The effect
of variation is more marked when we observe glass ot
more complicated composition. We can understand
that those which contain comparable quantities of the
two alkalies, soda and potash, may be more subject
to these modifications than those having a more
simple composition based on a single alkali.

Effects of Annealing. — A piece of brass wire that
has been drawn and then heated is the scene of
certain very remarkable internal changes, and these
have been only recently recognized. The violent
treatment of the metallic thread in forcing it through
the hole in the die has crushed the crystalline
particles ; the interior state of the wire is that of
broken crystals embedded in a granular mass.
Heating changes all that. The crystals separate,
repair themselves, and are built up again; they are
then hard, geometrical bodies, in an amorphous,
relatively soft and plastic mass; their number keeps
on increasing; equilibrium is not established until the
entire mass is crystallized. We may imagine how
many displacements, enormous when compared with
their dimensions, the molecules have to undergo when
passing through the resisting mass, and arranging
themselves in definite places in the crystalline
structures.

276 LIFE AND DEATH.

in the same way, too, in the manufacture of steel,
the particles of coal at first applied to the surface
pass through the iron.

This faculty of molecular displacement enables the
metal in some cases to modify its state at one point
or another. The use made of this faculty under
certain circumstances is very curious, greatly re-
sembling the adaptation of an animal to its environ-
ment, or the methods of defence against agents that
might destroy it.

Ejfect of Stretching. Hartinann's Experiment. —
When a cylindrical rod of metal, held firmly at either
end — a test-piece, as it is called in metallurgy — is
pulled "sufficiently hard, it often elongates consider-
ably, part of the elongation disappearing as soon as
the strain ceases, and the other part remaining. The
total elongation is thus the sum of an " elastic
elongation," which is temporary, and a " permanent
elongation." If we continue the stretching, there
appears at some point of the rod a local extension
with contraction of sectional area. It is here that the
rod will break.

But in place of continuing the stretching, Mr.
Hartmann suspends it. He stops, as if to give the
"metal-being" time to rally. During this delay it
would seem that the molecules hasten to the menaced
point to reinforce and harden the weak part. In
fact the metal, which was soft at other points, at
this spot looks like tempered metal. It is no longer
extensible.

When the experimenter begins the stretching again
after this rest, and after the narrowed bar has been
rolled and become cylindrical again, the local ex-
tension and secUonal contraction is forced to occur at

EVOLUTION AND MUTABILITY OF MATTER. 277

another point. If another rest is given at this point
the metal will also become hardened.

If we repeat the experiment a sufficient number of
times, we shall find a total transformation of the rod,
which becomes hardened throughout its entire extent.
It will break rather than elongate if the stretching is
sufficiently severe.

Nickel Steels — tJieir ^'Heroic'"' Resistance. — Nickel
steels present this phenomena in an exaggerated
degree. The alternation of operations which we
have just described, bringing the various parts of an
ordinary steel rod into a tempered state, is not
necessary with nickel steel. The effect is produced
in the course of a single trial. As soon as there is
any tendency to contraction the alloy hardens at that
precise place ; the contraction is hardly noticeable ;
the movement is stopped at this point to attack
another weak point, stops there again and attacks a
third, and so on ; and, finally, the paradoxical fact
appears that a rod of metal which was in a soft state
and could be considerably elongated has now become
throughout its whole extent as hard, brittle, and
inextensible as tempered steel. It is in connection
with this point that M. C. E. Guillaume spoke of
••heroic resistance to rupture." It would seem, in
fact, as if the ferro-nickel bar had reinforced each
weak point as it was threatened. It is only at the
end of these efforts that the inevitable catastrophe
occurs.

Effect of Temperature. — When the temperature
changes, it is seen that these ferro-nickel bars elongate
or retract, modifying at the same time their chemical
constitution. But these effects, like those which occur
in the glass bulb of a thermometer, do not occur

278 LIFE AND DEATH.

at once. They are produced rapidly for one part, and
more slowly for a small remaining portion. Bars of
ferro-nickel which have been kept at the same
temperature change gradually in length in the course
of a year. Can we find a better proof of internal
activity occurring in a substance differing so greatly
from living matter?

Nature of the Activity of Particles. — These are
examples of the internal activity that occurs in brute
bodies. Besides, these facts that we are quoting
merely to refute Bichat's assertion relative to the
immutability of brute bodies, and to show us their
activity, also afford us another proof. They show
that this activity, like that of animals, wards off
foreign intervention, and that this parrying of the
attack, again like that of animals, is adapted for the
defence and preservation of the brute mass. So that
if we consider of special importance the adaptative,
teleological characteristic of vital phenomena, a
characteristic which is so easily made too much of
in biological interpretations, we may also find it
again in the inanimate world. To this end we may
add to the preceding examples one more which is
no less remarkable. This is the famous case of
Becquerel's process for colour-photography.

Colour- Photography. — A greyish plate, treated with
chloride or iodide of silver and exposed to a red light,
rapidly becomes red. It is then exposed to green
light, and after passing through dull and obscure
tints it becomes green. To explain this remarkable
phenomenon, we cannot improve on the following
statement :— The silver salt protects itself against
the light that threatens its existence ; that light
causes it to pass through all kinds of stages of

EVOLUTION AND MUIABILITY OF MATTER. 279

coloration before reducing it ; the salt stops at the
stage which protects it best. It stops at red, if it is
red light that assails it, because in becoming red by
reflection it best repels that light — i.e., it absorbs it
the least.

It may then be advantageous, for the compre-
hension of natural phenomena, to regard the trans-
formation of inanimate matter as manifestations of a
kind of internal life.

Conclusion. Relations of the Surrounding Medium
to the Living Being and the Brute Body. — Brute
bodies, then, are not immutable any more than are
living bodies. Both depend on the medium that
surrounds them, and they depend upon it in the
same way. Life brings together, brings into conflict,
an appropriate organism and a suitable environment.
Auguste Comte and Claude Bernard have taught
us that vital phenomena fesult from the reciprocal
action of these two factors which are in close corre-
lation. It is also from the reciprocal action of the
environment and the brute body that ineyitably
result the phenomena which that body presents.
The living body is sometimes more sensitive to
variations of the ambient medium than is the brute
body, but at other times the reverse is the case.
For example, there is no living organism as im-
pressionable to any kind of stimulus whatever as the
bolometer is to the slightest variations of temperature.

There can only be, then, one chemically immutable
body — namely, the atom of a simple body, since, by
its very definition, it remains unaltered and intangible
in combinations. This notion of an unalterable atom
has, however, itself been attacked by the doctrine of
the ionization of particles due to Sir J. J. Thomson;

19

28o LIFE AND DEATH.

and besides, with very few exceptions — those of
cadmium, mercury, and the gases of the argon series
— the atoms of simple bodies cannot exist in a free
state.

Thus, as in the vital struggle, the ambient medium
by means of alimentation furnishes to the living being,
whether whole or fragmentary, the materials of its
organization and the energies which it brings into play.
It also furnishes to brute bodies their materials and
their energies.

It is also said that the ambient medium furnishes
to the living being a third class of things, the
stinmli o{ lis activities — i.e., its "provocation to action."
The protozoon finds in the aquatic environment
which is its habitat the stimuli which provoke it to
move and to absorb its food. The cells of the
metazoon encounter in the same way in the lymph,
the blood, and the interstitial liquids which bathe
them, the shock, the stimulus which brings their
energies into play. They do not derive from them-
selves, by a mysterious spontaneity without parallel
in the rest of nature, the capricious principle which
sets them in motion.

Vital spontaneity, so readily accepted by persons
ignorant of biology, is disproved by the whole history
of the science. Every vital manifestation is a response
to a stimulus, a provoked phenomenon. It is un-
necessary to say this is also the case with brute
bodies, since that is precisely the foundation of the
great principle of the inertia of matter. It is plain
that it is also as applicable to living as to inanimate
matter.

CHAPTER V.
Specific Form. Living Bodies and Crystals.

§ I. Specific form and chemical constitution — The wide dis-
tribution of crystalline forms — Organization of crystals —
Law of relation between specific form and chemical
constitution — Value of form as a characteristic of brute
and living beings — Parfentage, living beings and mineral
parentage — Iso-morphism and the faculty of cross-breeding
— Other analogies, i^ 2. Acquisition and re-establishment
of the specific form — Mutilation and regeneration of crystals
— Mechanism of reparation.

§ I. Specific Form and Vhemical Constitution. — In
the enumeration which we have made of the essential
features of vitality there are three that are, so to
speak, of the highest value. They are, in the order of
their importance : — The possession of a specific form ;
the faculty of growth or nutrition ; and finally, the
faculty of reproduction by generation. By restricting
our comparison between brute bodies and living
bodies to these truly fundamental characters we
sensibly restrict the field, but we shall see that it
does not disappear.

Wide Distribution of Crystalline Forms. — The
consideration of specific forms shows us that in
the mineral world we need only consider crystallized
bodies, as they are almost the only ones that possess
definite form. In restricting ourselves to this category
we do not limit our field as much as might be sup-

281

282 LIFE AND DEATH.

posed. Crystalline forms are very widely distributed.
They are, in a measure, universal. Matter has a
decided tendency to assume these forms whenever the
physical forces which it obeys act with order and
regularity, and when their action is undisturbed by
accidental occurrences. In the same way, too, living
forms are only possible in regulated environments,
under normal conditions, protected from cataclysms
and convulsions of nature.

The possession of a specific form is the most
significant feature of an organized being. Its
tendency, from the time it begins to develop from
the germ, is toward the acquirement of that form.
The progressive manner in which it seeks to realize
its architectural plan in spite of the obstacles and
difficulties that arise — healing its wounds, repairing
its mutilations — all this, in the eyes of the philo-
sophical biologist, forms what is perhaps the most
.striking characteristic of a living being, that which
best shows its unity and its individuality. This
property of organogenesis seems pre-eminently the
vital property. It is not so, however, for crystalline
bodies possess it in an almost equal degree.

The parallel between the crystal and a living being
has been often drawn. I will not reproduce it here
in detail. My sole desire, after sketching its principal
features, is to call attention to the new information
that has been brought out by recent investigations.

Organization of Crystals. Views of Haily, Delafossc,
Bravais, and of Wallerant. — In botany, zoology,
and crystallography we understand by form an
assemblage of material constituents co-ordinated in
a definite system — i.e., the organization itself The
body of man, for example, is an edifice in which sixty

SPECIFIC FORM. • , 283

trillion cells ought each to find its own predetermined
place.

In crystallography also we understand by form the
organization which crystals present. The grouping
of the elements of crystals is, perhaps, more simple.
They are none the less organized, in the same sense
that living bodies are.

Their organization, while more uniform than that
of living bodies, still shows a considerable amount of
variation. It should not be assumed that the area of
a crystal is completely filled, with contiguous parts
applied one to the other by plane faces, as might be
supposed from the phenomenon of cleavage which
dissociates the parts of the crystalline body into
solids of this kind. In reality, the constituent parts
are separated from each other by spaces. They are
arranged in a quincunx, aS Hauy put it, or along the
lines of a network, to use the terms of Delafosse and
Bravais. The intervals left between them are incom-
parably larger than their diameters. So that in the
organization of a crystal it is necessary to take into
account two quite different things : — An element, the
crystalline particle, which is a certain aggregate of
chemical molecules having a determinate geometrical
form ; and a more or less regular, parallelopipedic net-
work, along the edges of which are arranged in a con-
stant and definite manner the aforesaid particles. The
external form of the crystal indicates the existence
of the network. Its optical properties depend upon
the action of the particles, as Wallerant has shown :
Thus we must distinguish in a crystal between two
kinds of geometrical figures — that of the network
and that of the particle — and their characters of
symmetry may be either concordant or discordant

284 LIFE AND DEATH.

The crystalline particle, the element of the crystal,
is therefore a certain molecular complex that repeats
itself identically and is identically placed at the
nodes of the parallelopipedic network. It has been
given different names well calculated to produce
confusion — the crystallographic molecule of Mallard,
the complex particle of other authors. Some have
separated this element into subordinate elements
(the fundamental particles of Wallerant and of
Lapparent).

These very general outlines will suffice to show
how complex and adjustable is the organization of
the crystalline individual, which in spite of its
geometric regularity and its rigidity, may be com-
pared with the still more flexible organization of the
living element. The mineral individual is more
stable, more labile — i.e., less prone to undergo change
than is the living individual. We may say with
M. Lapparent that "crystallized matter presents the
most perfect and stable orderly arrangement of
which the particles of bodies are susceptible."

Law of Relation of Specific Form to CJieniical
Constitution. — Crystallization is a method of acquiring
specific form. The geometrical architecture of the
mineral individual is but little less wonderful or
characteristic than that of the living individual. Its
form is the result of the mutual reactions of its
substances and of the medium in which it is pro-
duced ; it is the condition of material equilibrium
corresponding to a given situation. This idea of a
specific form belonging to a given substance under
given conditions must be borne in mind. We may
consider it as a kind of principle of nature, an
elementary law, which may srerve as a point of

SPECIFIC FORM. ' .. 2S5

departure for the explanation of phenomena. A
particular substance under identical conditions of
environment, must always assume a certain form.

This close linking of substance and form, admitted
as a postulate in physical sciences, has been carried
into biology by some philosophical naturalists, by
M. Le Dantec, for instance.

Let us imitate them for a moment. Let us cease
to seek in the living being for the prototype of the
crystal ; let us, on the contrary, seek in the crystal the
prototype of the living being. If we succeed in this,
we shall then have found the physical basis of life.

Let us say, then, with the biologists we have
mentioned, that the substance of each living being is
peculiar to it ; that it is specific,, and that its form —
that is to say its organization — follows from it. The
morphology of any being whatever, of an animal —
of a setter, for example — or even of a determinate
being — of Peter, of Paul — is the " crystalline form of
their living matter." It is the only form of equili-
brium that can be assumed under the given conditions
by the substance of the setter, of Peter, or of Paul,
just as the cube is the crystalline form of sea-salt.
In this manner these biologists have supposed that
they could carry back the problem of living form
to the problem of living substance, and at the same
time reduce the biological mystery to the physical
mystery. I have shown above (Chap. V. pp. 199-204)
how far this idea is legitimate, and how far and with
what restrictions it may be welcomed and adopted.

Value of Form as a Characteristic of Living and
Brute Beings. — However this may be, we may say,
without fear of exaggeration, that the crystalline form
characterizes the mineral with no less precision than

286 LIFE AND DEATH.

the anatomical form characterizes the animal and the
plant. In both cases, form — regarded as a method
of distribution of the parts — indicates the individual
and allows us to diagnose it with more or less facility.

Parentage of Living Beings and Mineral Parent-
age.— Still another analogy has been noted. In
animals and plants similarity in forrn indicates
similarity in descent, community of origin, and
proximity in any scheme of classification. In the
same way identity of crystalline form indicates
mineral relationship. Substances chemically analo-
gous show identical, geometrically superposable
forms, and are thus arranged in family or generic
groups recognizable at a glance.

Isomorphism and the Faculty of Cross-breeding. —
And further, the possibility in the case of isomorphous
bodies, of their replacing each other in the same crystal
during the process of formation and of thus mingling,
so to speak, their congenital elements, may be
compared with the possibility of inter-breeding with
living beings of the same species. Isomorphism is
thus a kind of faculty of crossing. And as the
impossibility of crossing is the touchstone of taxo-
nomic relationship, testing it, and separating stocks
that ought to be separated, so the operation of
crystallization is also a means of separating from an
accidental mixture of mineral species the pure forms
which are blended therein. Crystallization is the
touchstone of the specific purity of minerals ; it is the
great process in chemical purification.

Other Analogies. — The analogies between crystal-
line and living forms have been pushed still further
even to the verge of exaggeration.

The internal and external symmetry of animals

SPECIFIC FORM. •- 287

and plants has been compared to that of crystals.
Transitions or intergradations have been sought
between the rigid and faceted architecture of the
latter and the flexible structure and curved surface of
the former ; the utricular form of flowers of sulphur
on the one hand, and the geometrical structure of the
shells of radiolarians on the other, have shown an
exchange of typical forms between the two systems.
An effort has even been made to draw a parallel
between six of the principal types of the animal
kingdom and the six crystalline systems. If carried
as far as this, our thesis becomes puerile. Real
analogies will suffice. Among these the curious facts
of crystalline renewal come first.

§ 2. Cicatrization in LiyiNG Beings and in
Crystals.

We know that living beings not only possess a
typical architecture which they have themselves
constructed, but that they defend it against de-
structive agencies, and that if need arise they repair
it. The living organism cicatrizes its wounds, repairs
losses of substance, regenerates more or less perfectly
the parts that have been removed ; in other terms,
when it has been mutilated it tends to reconstruct
itself according to the laws of its own morphology.
This phenomenon of reconstitution or reintegration,
these more or less successful efforts to re-establish its
form and its integrity, at first appear to be a char-
acteristic feature of living beings. This is not the
case.

Mutilation and Re-iniegration of Crystals. — Crys-
tals— let us say crystalline individuals — show a

288 LIFE AND DEATH.

similar aptitude for repairing their mutilations.
Pasteur, in an early work, discussed these curious
facts. Other experimenters, Gernez a little later and
Rauber more recently, took up the same subject, but
could do no more than extend and confirm his
observations. Crystals are formed from a primitive
nucleus, as the animal is formed from an egg ; their
integral particles are disposed according to efficient
geometrical laws, so as to produce the typical form
by a constructive process that may be compared to
the embryogenic process which builds up the body of
an animal. Now this operation may be disturbed by
accidents in the surrounding medium or by the
deliberate intervention of the experimenter. The
crystal is then mutilated. Pasteur saw that these
mutilations repaired themselves. " When," said he,
" a crystal from which a piece has been broken off is
replaced in the mother liquor, we see that while it
increases in every direction by a deposit of crystalline
particles, activity occurs at the place where it was
broken off or deformed ; and in a few hours this
suffices not only to build up the regular amount
required for the increase of all parts of the crystal,
but to re-establish regularity of form in the mutilated
part." In other words, the work of formation of the
crystal is carried on much more actively at the point
of lesion than it would have been had there been no
lesion. The same thing would have occurred with a
living being.

Mechanism of Reparation. — Gernez some years later
made known the mechanism of this reparation, or, at
least, its immediate cause. He showed that on the
injured surface the crystal becomes less soluble than
on the other facets. This is not, however, an ex-

SPECIFIC FORM. -.289

cepti'onal phenomenon. It is, on the contrary, quite
frequently observed that the different faces of a
crystal show marked differences in solubility. This
is what happens in every case for the mutilated face
in comparison with the others ; the matter is less
soluble there. The consequence of this is clear ; the
growth must preponderate on that face, since there
the mother liquor will become super-saturated beforS
being super-saturated for the others. We may
explain this result in another way. Each face of the
crystal in contact with the mother liquor is exposed
to two antagonistic actions : The matter deposited
upon a surface may be taken away and redissolved if,
for any reason whatever, such matter becomes more
soluble than that of the liquid stratum in contact
with it ; in the second place, the matter of this liquid
stratum may, under contrary conditions, be deposited?
and thus increase the body of the crystal. There is,
then, for each point of the crystalline facet, a positive
operation of deposit which results in a gain, and a
negative operation of redissolution which results in a
loss. One or the other effect predominates according
as the relative solubility is greater or less for the
matter of the facet under consideration. On the
mutilated surface it is diminished, deposition then
prevails.

But this is only the immediate cause of the
phenomenon ; and if we wish to know why the
solubility has diminished on the mutilated surface
Ostwald explains it to us by showing that crystal-
lization tends to form a polyhedron in which the
surface energy is a relative mimimum.

CHAPTER VI.

NUTRITION IN THE LIVING BEING AND IN THE
CRYSTAL.

Assimilation and growth in the crystal. — Methods of growth
in the crystal and in the living being ; intussusception ;
apposition. — Secondary and unimportant character of the
process of intussusception.

I HAVE already stated (Chap. VI. p. 209) that nutrition
may be considered as the most characteristic and
essential property of living beings. Such beings arc
in a state of continual exchange with the surrounding
medium. They assimilate and dissimilate. By as-
similation the substance of their being increases at
the expense of the surrounding alimentary material,
which is rendered similar to that of the being itself

Assimilation mid Growth in the Crystal. — There
exists in the crystal a property analogous to nutrition,
a kind of nutrility, which is the rudiment of this
fundamental property of living beings. The develop-
ment of a crystal starts from a primitive nucleus, the
germ of the crystalline individual that we will
presently compare to the ovum or embryo of a plant
or an animal. Placed in a suitable culture-medium —
i.e., in a solution of the substance — this germ
develops. It assimilates the matter in solution,
incorporates the particles of it, and increases, pre-
serving at the same time its form, reproducing its

290

NUTRITION IN THE LIVING BEING. 39I

specific type or a variety of it. Its growth proceeds
without interruption. The crystalline individual may
attain quite a large size if we know how to nourish it
properly — we might say, to fatten it. Very fre-
quently, at a given time, a new particle of the crystal
serves in its turn as a primitive nucleus, and becomes
the point of departure for a new crystal engrafted
upon the first.

Taken from its mother liquor, placed where it
cannot be nourished, the crystal, arrested in its
growth, falls into a condition of rest not without
analogy to that of a seed or of a reviviscent animal.
Its evolution is resumed with the return of favourable
conditions — the bath of soluble matter.

The crystal is in a relation of continual exchange
with the surrounding medium which feeds it. These
exchanges are regulated by the state of this medium,
or, more exactly, by the state of the liquid stratum
which is in immediate contact with the crystals. It
loses or it gains in substance if, for example, this
layer becomes heated or cooled more rapidly than the
crystal. In a general way, it assimilates or dissimilates
according as its immediate environment is saturated
or diluted. Here, then, we have a kind of mobile
equilibrium, comparable, in some measure, to that of
the living being.

Methods of Growth of the Crystal and of the Living
Being. Intussusception. Apposition. — In truth, there
seems to be a complete opposition between the crystal
and the living being as regards their manner of
nutrition and growth. In the one case the method is
intussusception ; in the other it is apposition. The
crystalline individual is all surface. Its mass is im-
penetrable to the nutritive materials. Since only the

292 LIFE AND DEATH.

surface is accessible, the incorporation of similar
particles is possible only by external juxtaposition,
and the edifice increases only because a new layer of
stones has been added to those which were there
before. On the contrary, the body of an animal is a
mass essentially penetrable. The cellular elements
that compose it have more or less rounded and
flexible forms. Their contact is by no means perfect.
They have neither the stiffness nor the precision
of adjustment that the crystalline particles have.
Liquids and gases can insinuate themselves from
without and circulate within the meshes of this loose
construction. Assimilation can therefore take place
throughout its whole depth, and the edifice increases
because each stone is itself increasing.

The Secondary and Commonplace Character of the
Process of Intussusception. — The apparent opposition
of these two processes is doubtless diminished if we
compare the simple mineral individual with the
elementary living unit, the crystalline particle with
the protoplasmic mass of a cell. Without carrying
analysis so far as this, it is yet easy to see that appo-
sition and intussusception are mechanical means
that living beings employ at one and the same time
and combine according to their necessities. The hard
parts of the internal and external skeleton increase
both by interposition and superposition, at once. It
is by the last method that bones increase in diameter,
and the shells of molluscs, the scales of reptiles and
fishes, and the testae of many radiate animals are
formed. In these organs, as in crystals, life and
nutrition occur at the surface.

Apposition and intussusception are then secondary,
mechanical arrangements having relation to the

NUTRITION IN THE LIVING BEING. "' 2g3

physical characters of the body — solidity in the
crystal, semi-fluidity in the cellular protoplasm. If
we compare the inorganic liquid matter with the
semi-fluid organized matter, we recognize that the
addition of substance takes place in the same manner
in each — i.e., by interposition. If we add a soluble
salt to a fluid, the molecules of the salt separate
themselves and interpose themselves between those
of the fluid. There is, therefore, nothing especially
mysterious or particularly vital about the process of
intussusception. Applied to fluid protoplasm, it is
merely the diffusion that ordinarily occurs in mixed
liquids.

■ CHAPTER VII.

GENERATION IN BRUTE BODIES AND LIVING
BODIES. SPONTANEOUS GENERATION.

Protoplasm a substance which continues — Case of the crystal —
Characteristics of generation in the living being — Property
of growth — Supposed to be confined to the living being —
Fertilization of micro-organisms— Fertilization of crystals —
Sterilization of crystalline and living media — Spontaneous
generation of crystals — Metastable and labile zones —
Glycerine crystals — Possible extinction of a crystalline
species — Conclusion.

We have not yet exhausted the analogies between a
crystal and the living being. The possession of a
specific form, the tendency to re-establish it by re-
disintegration and the existence of a kind of nutrition
are not sufficient to constitute complete similarity.
It still lacks a fundamental character, that of genera-
tion. Chauffard some time ago, in an attack which
he made upon the physiological ideas of his day,
aptly exhibited this weak point. " Let us disregard,"
he said, "those interesting facts relative to the acquisi-
tion of a typical form — facts that are common to the
mineral world as well as to living beings. It is none
the less true that the crystalline type is in no wa}-
derived from other pre-existing types, and that
nothing in crystallization recalls the actions ot
ascendants and the laws of heredity."

This gap has since been filled. Th^ work of
294

SPONTANEOUS GENERATION. ' 295

Gernez, of Violette, of Lecoq de Boisbaudran, the ex-
periments of Ostwald and of Tammann, the observa-
tions of Crookes and of Armstrong — all this series of
researches, so lucidly summarized by M. Leo Errera
in his essays in botanical philosophy, had for their
result the establishment of an unsuspected relation
between the processes of crystallization and those of
generation in animals and plants.

Protoplasm is a Substance ivJiich Continues. The
Case of the Crystal. — Under present conditions a living
being of any kind springs from another living being
similar to itself.

Its protoplasm is always a continuation of the
protoplasm of an ancestor. It is an atavic substance
of which we do not see the beginning; we only see it
continue. The anatomical element comes from a
preceding anatomical element, and the higher animal
itself comes from a pre-existing cell of the material
organism, the ovum. The ladder of filiation reaches
back indefinitely into the past.

We shall see that there is something analogous to
this in certain crystals. They are born of a preceding
individual; they may be considered as the posterity
of the antecedent crystal. If we speak of the matter
of a crystal as the matter of a living being is spoken
of, in cases of this kind we would say that the
crystalline substance is an atavic substance of which
we see only the continuation, as in the case of
protoplasm.

Characters of Generation in the Living Being.— ^
Growth of the living substance, and consequently of
the being itself, is the fundamental law of vitality.
Generation is the necessary consequence of growth
(p. 210).

20

296 LIFE AND DEATH.

Living elements or cells cannot subsist indefinitely
without increasing and multiplying. The time must
come when the cell divides, either directly or in-
directly; and then, instead of one cell, there are two.
This is the method of generation for the anatomical
element. In a complex individual it is a more or less
restricted part of the organism, usually a simple
sexual cell, that takes on the formation of the new
being, and assures the perpetuity of the protoplasm,
and therefore of the species.

Property of Grozvth. Its Supposed Restriction to
Living Beings. — At first it would appear that nothing
like this occurs in inanimate nature. The physical
machine, if we furnish it matter and energy, could go
on working indefinitely, without being compelled to
increase and reproduce. Here, then, there is an
entirely new condition peculiar to the organized
being, a property well adapted, it would seem — and
this time without any possible doubt — for separating
living matter from brute matter. It is not so.

It would not be impossible to imagine a system
of chemical bodies organized like the animal or
vegetable economy, so that a destruction would be
compensated for by a growth. The only thing im-
possible is to suppose, with M. le Dantec, a destruction
that would at the same time be an analysis. And an
additional perplexity occurs when he supposes that
in the successive acts exchanges of material may
occur.

There is no necessity for making this impossible
chemistry a characteristic of the living being. The
chemistry of the living being is general chemistry.
Lavoisier and Berthelot enforced this view. We
should not lose sight of the teachings of the masters.

SPONTANEOUS GENERATION. 297

Let US return to generation, properly so called, and
find in it the characteristics of brute bodies and of
crystals.

TJie Solving of Micro-orgamsms. — When a micro-
biologist wishes to propagate a species of micro-,
organisms, he places in a culture medium a few
individuals (one is all that is actually necessary), and
soon observes their rapid multiplication. Usually, if
only the ordinary microbes in atmospheric dust are
wanted, the operator need not trouble to charge the
culture; if the culture tube remains open and the
medium is suitably chosen, some germ of a common
species will fall in and the liquid will become
colonized. This has the appearance of spontaneous
generation.

TJie Sowing of Crystals. — Concentrated solutions of
various substances, supersaturated solutions of sodium
magnesium sulphate, and sodium chlorate are also
wonderful culture media for certain mineral organic
units — certain crystalline germs. Ch. Dufour, ex-
perimenting with water cooled below 0° C, its point
of solidification ; Ostwald, with salol kept below SQ^-S,
its point of fusion ; Tammann, with betol, which
melts at 96° ; and, before them, Gernez, with melted
phosphorus and sulphur — all these physicists have
shown that liquids in superfusion are also media
specially appropriate for the culture and propagation
of certain kinds of crystalline individuals.

Some of these facts have become classic. Lowitz
showed in 1785 that a solution of sodium sulphate
could be concentrated by evaporation so as to contain
more salt than was conformable with the temperature,
without, however, depositing the excess. But if a
solid fragment, a crystal of salt, is thrown into the

298 LIFE AND DEATH.

liquor, the whole of the excess immediately passes
into the state of a crystallized mass. The first
crystal has engendered a second similar to itself;
the latter has engendered a third, and so on from one
to the other. If we compare this phenomenon with
that of the rapid multiplication of a species of
microbes in a suitable culture medium, no difference
will be perceived. Or perhaps we may note one
unimportant difference — the rapidity of the propaga-
tion of the crystalline germs as opposed to the relative
slowness of the generation of the micro-organisms.

Again, the propagation of crystallization in a super-
saturated or superfused liquid may be delayed by
appropriate devices. The crystalline individual gives
birth, then, to another individual that conforms to its
own type, or even to varieties of that type when such
exist. Into the right branch of a U tube filled with
sulphur in a state of superfusion Gernez dropped
octahedric crystals of sulphur, and into the left branch
prismatic crystals. On either side were produced
new crystals conforming to the type that had been
sown.

Sterilization of Crystalline Media and Living Media.
— Ostwald varied these experiments by using salol.
He melted the substance by heating it above 39°.5 C;
then, protecting it from crystals of any kind, he let
the solution stand in a closed tube. The salol re-
mained liquid indefinitely — until it was touched with
a platinum wire that had been in contact with solid
salol — i.e.y until a crystalline germ was introduced.
But if the platinum wire has been previously sterilized
by passing it, as the bacteriologists do, through a
flame, it can then be introduced into the liquor with
impunity.

SPONTANEOUS GENERATION. 299

The Dimensions of Crystalline Germs Compar-
able to those of Microbes. — We may dilute the solid
salol with inert powder — lactin, for example — dilute
the first mixture with a second, the second with a
third, and so on; then, throwing into the solution of
surfused salol a tenth of a milligram from one of
these various mixtures, we find that the production of
crystals will not take place if the fragment thrown in
weighs less than a millionth of a milligram, or
measures less than ten thousandths of a millimetre
in length. It would seem, then, that these are the
dimensions of the crystalline particle or crystallo-
graphic molecule of salol. In the same way Ostwald
satisfied himself that the crystalline germ of hypo-
sulphite of soda weighs about a thousand-millionth of
a milligram, and measures a thousandth of a milli-
metre ; that of chlorate of soda weighs a ten-millionth
of a milligram. These dimensions are entirely com-
parable with those of microbes.

All these phenomena have been studied with a
detail into which it is impossible to enter here, and
which clearly shows more and more intimate analogies
between the formation of crystals and the generation
of micro-organisms.

Extension and Propagation of Crystallization.
Optimum Temperature of Incubation. — Crystallization
which has commenced around a germ is propagated
more or less rapidly, and ends by invading the whole
of the liquor.

The rapidity of this movement of extension depends
upon the conditions of the medium, especially upon
its temperature. This is shown very well by
Tammann's experiments with betol. This body,
the salicylic ester of naphthol, fuses at 96° C. If it

3O0 LIFE AND DEATH.

is melted in tubes sealed at a temperature of lOo" C,
it may be cooled to lower and lower temperatures —
to + 70°, to + 25°, to + 10°, to — 5° without solidifying.
Let us suppose that by some combination of circum-
stances a few centres of crystallization — that is to
say, of crystalline germs — have appeared in the
solution. Solidification will extend slowly at the
ordinary temperature, at 20° to 25° and thereabouts.
On the other hand, it will be propagated with great
rapidity if the liquor is kept at about 70°. This
point — 70° — is the thermal optimum for the pro-
pagation of germs. It is the most favourable
temperature for what may be called their incubation.
As soon as the germs find themselves in a liquor at
70° they increase, multiply, and show that they are in
the best conditions for growth.

Spontaneous Generation of Crystals. Optimum
Temperature for the Appearance of Germs. — If we
consider various supersaturated solutions or liquids
in superfusion, we shall soon discover that they can
be arranged in two categories. Some remain in-
definitely liquid under given conditions unless a
crystalline germ is introduced into them. Others
solidify spontaneously without artificial intervention,
and such crystallization may even be propagated very
rapidly under determinate conditions. This implies
that these are conditions favouring the spontaneous
appearance of germs.

This distinction between substances of crystalline
generation by filiation and substances of spontaneous
crystalline generation is not specific. The same
substance may present the two methods of generation
according to the conditions in which it is placed.
Betol furnishes a good example of this. Liquefy it at

SPONTANEOUS GENERATION. 3OI

100° in a sealed tube and keep it by means of a stove
above 30°, and it will remain liquid almost indefinitely.
On the other hand, lower its temperature and leave it
for one or two minutes at 10°, and germs will appear
in the liquor; prolong the exposure to this degree of
heat and the number of these spontaneously appearing
germs, appearing in isolation,' will rapidly increase.
On the other hand, you will observe that propagation
by filiation — that is to say, by extension from one
to another — is almost absent. The temperature of
10° is not favourable to that method of .generation ;
and we have just seen, in fact, that it is at a tem-
perature of about yo" that extension of crystallization
from one to another is best accomplished. The
temperature of 70° was the optimum for propagation
by filiation. Inversely, the temperature of 10° is the
optimum for spontaneous generation. Above and
below this optimum the action is slower. We may
count the centres of crystallization, which slowly
extend further and further, as in a microbic
culture one counts the colonies corresponding to
the germs primitively formed. To sum up, if
there is an optimum for the formation of
crystals, there is a different optimum for their rapid
extension.

The Metastable and Labile Zones. — This phenomena
is general. There is for each substance a set of
conditions (temperature, degree of concentration,
volume of the solution) in which the crystalline
individuals can be produced only by germs or by
filiation. This is what occurs for betol above the
temperature of 30°. The body is then in what
Ostwald has called a metastable zone. There is,
however, for the same body another set of circum-

302 LIFE AND DEATH.

stances more or less complete, in which its gems
appear simultaneously. This is what happens for
betol at about the temperatute of io°. These circum-
stances arc those of the labile zone or zone of
spontaneous generation.

Crystals of Glycerine. — We may go a step further.
Let us suppose, with L. Errera, that we have a liquid
in a state of metastable equilibrium, whose labile
equilibrium is as yet unknown. This is what actually
occurs for a very widely known body, glycerine.
We do not know under what conditions glycerine
crystallizes spontaneously. If we cool it, it becomes
viscous ; we cannot obtain its crystals in that way.
It was not found in crystals until 1867. In that
year, in a cask sent from Vienna to London during
winter, crystallised glycerine was found, and Crookes
showed these crystals to the Chemical Society of
London. What circumstances had determined their
formation ? We knew not then, and we know not
now. It may be observed that this case of spon-
taneous generation of the crystals of glycerine has
not remained the solitary instance. M. Henninger
has noted the accidental formation of glycerine
crystals in a manufactory in St. Denis.

It may be remarked that this crystalline species
appeared, as livin-g species may have done, at a given
moment in an environment in which a favourable
chance combined the necessary conditions for its
production. It is also quite comparable to the
creation of a living species ; for having once appeared
we have been able to perpetuate it. The crystalline
individuals of 1867 have had a posterity. They
have been sown in glycerine in a state of superfusion, -
and there they reproduced themselves. These

SPONTANEOUS GENERATION. 303

generations have been sufficiently numerous to
spread the species throughout a great part of
Europe. M. Hoogewerf showed a great flask full
to the Dutch biologists who met at Utrecht in
1 89 1. M. L. Errera presented others in June 1899,
to the Society of Medical and Natural Sciences at
Brussels. To-day the great manufactory of Sarg &
Co., of Vienna, is engaged in their production on a
large scale for industrial purposes.

Thus we are able to study this crystalline species
of glycerine and to determine with precision the
conditions of its continued existence. It has been
shown that it does not resist a temperature of 18°, so
that if precautions were not taken to preserve it,
a single summer would suffice to annihilate all the
crystalline individuals existing on the surface of the
globe, and thus the species would be extinguished.

Possible Extinction of a Crystalline Species. — As
these crystals melt at 18°, this temperature represents
the point of fusion of solid glycerine or the point of
solidification of liquid glycerine. But the liquor
does not solidify at all if its temperature falls below
18° C, as we well know, for it is at that temperature
we use it. Nor does it solidify at zero, nor even at
18° below zero ; at 20°, for instance, it merely thickens
and becomes pasty. We only know glycerine, then, in
a state of superfusion, a fact which chemists have not
learned without amazement. Under these conditions,
so analogous to the appearance of a living species, to
its unlimited propagation and to its extinction, the
mineral world offers a quite faithful counterpart to
the animal world. The living body illustrates here
the history of the brute body and facilitates its
exposition. Inversely, the brute body in its turn

304 LIFE AND DEATH.

throws remarkable light on the subject of the living
body, and on one of the most serious problems
relative to its origin, that of spontaneous generation.

Conclusion. — These facts lead to one conclusion.
Until the concourse of propitious circumstances
favourable to their spontaneous generation was
brought about, crystals were obtained only by
filiation. Until the discovery of electro-magnetism,
magnets were made only by filiation, by means of
the simple or double application of a pre-existing
magnet. Before the discovery which fable attributes
to Prometheus, every new fire was produced only by
means of a spark from a pre-existing fire. We are
at the same historical stage as regards the living
world, and that is why, up to the present, there has
never been formed a single particle of living matter
except by filiation, except by the intervention of a
pre-existing living organism.

BOOK V.

SENESCENCE AND DEATH.

Chap. I. The different points of view from which death may be
regarded. — Chap. II. Constitution of the organisms —
Partial death — Collective death. — Chap. III. Physical
and chemical characteristics of cellular death — Necrobiosis.
Chap. IV. Apparent perennity of complex individuals. —
Chap. V. Immortality of the protozoa and of slightly
differentiated cells.

We grow old and we die. We see the beings
which surround us grow old and disappear. At first
we see no exceptions to this inexorable law, and we
consider it as a universal and inevitable law of
nature. But is this generalization well founded ?
Is it true that no being can escape the cruel fate of
old age and death, to which we and all the repre-
sentatives of the higher animality are exposed ? Or,
on the other hand, are any beings immortal ? Biology
answers that, in fact, some beings are immortal.
There are beings to whose life no law assigns a
limit, and they are the simplest, the least differentiated
and the least perfect. Death thus appears to be a
singular privilege attached to organic superiority, the
ransom paid for a masterly complexity. Above these
elementary, monocellular, undifferentiated beings,
which are protected from mortality, we find others,
higher in their organization, which are exposed to

305

306 LJFE AND DEATH.

it, but with whom death seems but an accident,
avoidable in principle if not in fact. The anatomical
elements of this higher animal are a case in point.
Flourens once tried to persuade us that the threshold
of old age might be made to recede considerably, and
there are biologists in the present day who give us
some glimpse of a kind of vague immortality. We
may, therefore, ask our readers to follow us in our
examination of these re-opened if not novel questions,
and we shall explain the views of contemporary
physiology as to the nature of death, its causes, its
mechanisms, and its signs.

CHAPTER I.

VARIOUS WAYS OF REGARDING DEATH.

Different meanings of the word death — Physiological distinction
between elementary and general death — Non-scientific
opinions — The ordinary point of view — Medical point of
view. — The signs of death are prognostic signs.

Different Meanings of tJie Word Death. — An English
philosopher has asserted that the word we translate
by " cause " has no less than sixty-four different mean-
ings in Plato and forty-eight in Aristotle. The word
" death " has not so many meanings in modern
languages, but still it has many. Sometimes it
indicates an action which is taking place, the action
of dying, and sometimes a state, the state which
succeeds the action of dying. The phenomena it
connotes are in the eyes of many biologists quite
different, according as we watch them in an animal
of complex organization, or on the other hand, in
monocellular beings, protozoa and protophytes.

Physiological Distinction between Elementary Death
and General Death. — We distinguish the death of the
anatomical elements, elementary deatJi, from the
death of the individual regarded as a whole, general
death. Hence we recognize an apparent death, which
is an incomplete and temporary suspension of the
phenomena of vitality, and a real death, which is a
final and total arrest of these phenomena. When

307

308 LIFE AND DEATH.

we consider it in its essential nature (assumed, but
not known) we look on it as the contrary of life, as
did the Encyclopaedia, Cuvier, and Bichat ; or we
regard it with others either as the consequence of
life, or simply as the end of life.

Non-scientific Opinions, — What is death to those
outside the realm of science? First of all we find the
consoling solution given by those who believe death
to be the commencement of another life. We next
find ourselves involved in a confused medley, an
infinite diversity of philosophical doubt and super-
stition. " A leap into the unknown," says one.
" Dreamless and unconscious night," says another.
And again, " A sleep which knows no waking."
Or, with Horace, " the eternal exile," or with
Seneca, annihilation. Post iuorte»i niJiil ; ipsaqiie
mors nihil.

The idea which is constantly supervening in the
midst of this conflict of opinion is that of the
breaking up of the elements, the union of which
forms the living being. It has, as we shall see, a
real foundation which may perhaps receive the
support of science. We shall not find that the Best
way of defining death is to say that it consists of the
" dissolution of the society formed by the anatomical
elements, or again, in the dissolution of the conscious-
ness that the individual possesses of himself — i.e , of
the existence of this society." It is the rupture of
the social bond. The old idea of dispersion is a
variant of the same notion. But the ancients
evidently could not understand, as we do, the nature
of these elements which are associated to form the
living being, and which are liberated or dispersed
by death. We, as biologists, can see microscopical

VARIOUS WAYS OF REGARDING DEATH. 309

organic unity with a real objective existence. The
ancients were thinking of spiritual elements, of
principles, of entities. To the Romans, who may be
said to have held that there are three souls, death
was produced by their separation from the body.
The first, the breath, the spirit us, mounting towards
celestial regions {astra petit) ; the second, the shade,
remaining on the surface of the earth and wandering
around the tombs ; the third, the manes, descending
to the lower regions. The belief of the Hindoos was
slightly different. The body returned to the earth,
the breath to the winds, the fire of the glance to the
sun, and the ethereal soul to the world of the pure.
Such were the ideas of mortal dispersion formed by
ancient humanity.

Modern science takes a more objective point of
view. It asks by what facts, by what observable
events death is indicated. Generally speaking, we
may say that these facts interrupt an interior state
of things which was life and to which they put an
end. Thus death is defined by life. It is the
cessation of the events and of the phenomena which
characterize life. We must, therefore, know what
life is to understand the meaning of death. How
wise was Confucius when he said to his disciple,
Li-Kou : — " If we do not know life, how can we
know death ? " According to biology there are two
kinds of death because there are two kinds of life ;
elementary life and death correspond just as general
life and death do, and this is where scientific opinion
diverges from commonly received opinion.

What cares the man who reasons as most human
beings do, about this life of the anatomical elements
of his body, the existence and the silent activity of

310 LIFE AND DEATH.

which are in no way revealed to him. What does
their death matter to him ? To him there is but one
poignant question, that of being separated or not
being separated from the society of his fellows.
Death is no longer to feel, no longer to think ; it is
the assurance that one will never feel, one will never
think again. Sleep, dreamless sleep, is already in our
eyes a kind of transient death ; but, when we fall asleep
we are sure of waking again. There is no awaking
from the sleep of death. But that is not all. Man
knows that death, this dreamless sleep that knows no
waking, will be followed by the dissolution of his
body. And what a dissolution will there be for the
body, the object of his continual care I Remember
the description of Cuvier — the flesh that passes from
green to blue and from blue to black, the part which
flows away in putrid venom, the other part which
evaporates in foul emanations, and finally, the few
ashes that remain, the tiny pinch of minerals, saline
or earthy, which are all that is left of that once
animated masterpiece.

IJie Popular Vieiv. — To the man afraid of death
it seems, in the presence of so great a catastrophe,
that the patient analysis of the physiologist scrupu-
lously noting the succession of phenomena and ex-
plaining their sequence is uninteresting. He will
only attach the slightest importance to knowing that
vestiges of vitality remain in this or that part of his
body, if they do not re-establish in every part the
status quo ante. He cares not to hear that a certain
time after the formal declaration of his death his
nails and his hair will continue to grow, that his
muscles will still have the useless faculty of con-
traction, that every organ, every tissue, every element,

VARIOUS WAYS OF REGARDING DEATH. 31I

will oppose a more or less prolonged resistance to the
invasion of death.

Medical Vieiv. — It is, however, these very facts and
details, this why and wherefore, which interest the
physiologist. The state of mind of the doctor in this
respect, again, is different. When, for instance, the
doctor declares that such and such a person is dead,
he is really making not so much a statement of fact
as a prediction. How many elements are still living
and will be capable of new birth in this corpse that
he has before his eyes? That is not what he asks
himself, nor is it what we should ask of him. He
knows, besides, that all these partial survivals will be
extinguished and will never find the conditions
necessary to reviviscence, and that the organization
will never be restored to its primal activity ; and this
is what he affirms. The fear of premature burial
which haunts so many imaginations is the fear of an
error in the prediction. It is to avoid this that
practical medicine has devoted so much of its
attention to the discovery of a certain — and early —
sign of death. By this we understand the discovery
of a certain prognostic sign of general deatJi. We
want a prognostic sign enabling us to assert that the
life of the brain is now extinguished and will never
be reanimated. And yet there are in that organism
many elements which are still alive. Many others
even may be born anew if we could give them
suitable conditions which they no longer meet with
in the animal machine now thrown out of gear.
What finer example could we give than the experi-
ment of Kuliabko, the Russian physiologist, who
kept a man's heart working and beating for eighteen
hours after the official verification of his death.

21

CHAPTER II.

THE PROCESS OF DEATH.

Constitution of organisms. — Partial lives. — Collective life. — The
role of apparatus. — Death by lesion of the major appar-
atus.— The vital tripod.— Solidarity of the anatomical
elements. —Humoral solidarity. — Nervous solidarity. — In-
dependence and subordination of the anatomical elements.

Partial Lives. Collective Life. — With the exception
of the physiologist, no one, neither he who is ignorant
nor he who is intellectual, nor even the doctor,
troubles his head about the life or the death of the
element, although this is the basis, the real founda-
tion, of the activity manifested by the social body
and by its different organs. The life of the indi-
vidual, of the animal, depends on these elementary
partial lives just as the existence of the State depends
upon that of its citizens. To the physiologist, the
organism is a federation of cellular elements unified
by close association, Goethe compared them to a
" multitude " ; Kant to a " nation " ; and others have
likened them to a populous city the anatomical
elements of which are the citizens, and which pos-
sesses an individuality of its own. So that the
activity of the federated organism may be discussed
in each of its parts, and then it is elementary life, or
in its totality, and then it is general life. Paracelsus
and Bordeu had a glimpse of this truth when they
considered a life appropriate to each part {vita propria)

312

THE PROCESS OF DEATH. 313

and a collective life, the life of the whole {vita
commimis). In the same way we must distinguish
the elementary death, which is the cessation of the
vital phenomena in the isolated cell, from the general
death, which is the disappearance of the phenomena
which characterised the collectivity, the totality, the
federation, the nation, the city, the whole in so far as
it is a unit.

These comparisons enable us to understand how
general life depends on the partial lives of each
anatomical citizen. If all die, the nation, the federa-
tion, the total being clearly ceases to exist. This
city has an enormous population — there are thirty
trillion cellules in the body of man ; it is peopled
with absolutely sedentary citizens, each of which has
its fixed place, which it never leaves, and in which it
lives and dies. It must possess a system of more or
less perfect arrangements to secure the material life
of each inhabitant. All have analogous require-
ments : they feed very much the same ; they breathe
in the same way ; each in fact has its profession,
industry, talents, and aptitudes by which it contri-
butes to social life, and on which, in its turn, it
depends. But the process of alimentation is the
same for all. They must have water, nitrogenous
materials and analogous ternaries ; the same mineral
substances, and the same vital gas, oxygen. It is no
less necessary that the wastes and the egesta, very
much alike in every respect, should be carried off and
borne away in discharges arranged so as to free the
whole system from the inconvenience, the unhealthi-
ness, and the danger of these residues.

Secondaty Organization in Organs. — That is why,
as we said above, the secondary organizations of the

314 LIFE AND DEATH.

economy exist : — the digestive apparatus which pre-
pares the food and enables it to pass into the blood,
into the lymph, and finally into the liquid medium
which bathes each cell and constitutes its real
medium ; the respiratory apparatus which imports
the oxygen and exports the gaseous excrement,
carbonic acid; the heart and the circulatory system
which distributes through the system the internal
medium, suitably purified and recuperated. The
organization is dominated by the necessities of
cellular life. This is the law of the city, to which
Claude Bernard has given the name of the latv of the
constitution of organisms.

Death by Lesion of the Major Organs. Vital
Tripod. — Thus we understand what life is, and at the
same time what is the death of a complex living
being. The city perishes if its more or less compli-
cated mechanisms which look after its revictualling
and its discharge are seriously affected at any point.
The different groups may survive for a more or less
lengthy period, but progressively deprived of the
means of food or of discharge, they are finally
involved in the general ruin. If the heart stops,
there is a universal famine ; if the lungs are seriously
injured, we are asphyxiated ; if the principal organ
of discharge, the kidney, ceases to perform its allotted
task, there is a general poisoning by the used-up and
toxic materials retained in the blood.

We understand how the integrity of the major
organs, — the heart, the lungs, the kidney, — is indis-
pensable to the maintenance of existence. We
understand that their lesion, by a series of successive
repercussions, involves universal death. We always
die, said the doctors of old, because of the failure of

THE PROCESS OF DEATH. 315

one of these three organs, the heart, th: lungs, or the
brain. Life, they said in their inaccurate language,
depends upon these as upon three supports. Hence
the idea of the vital tripod. But it is not only this
trio of organs which maintain the organism ; the
kidney and the liver are no less important. In
different degrees each part exercises its action on the
rest. Life is based in reality on the immense
multitude of living cells associated for the formation
of the body ; on the thirty trillion anatomical ele-
ments, each part is more or less necessary to all the
rest, according as the bond of solidarity is drawn more
or less closely in the organism under consideration.

Death and the Brain. — There are indeed more noble
elements charged with higher functions than the rest.
These are the nervous elements. Those of the brain
preside over the higher functions of animality, sensi-
bility, voluntary movement, and the exercise of the
intellect. The rest of the nervous system forms an
instrument of centralization which establishes the
relations of the parts one with the other and secures
their solidarity. When the brain is stricken and its
functions cease, man has lost the consciousness of his
existence. Life seems to have disappeared. We say
of a man in this plight that he no longer lives, thus
confusing general life with the cerebral life which is
its highest manifestation. But the man or the
animal without a brain lives what may be called a
vegetative life. The human anencephalic foetus lives
for some time, just as the foetus which is properly
formed. Observation always shows that this exist-
ence of the other parts of the body cannot be sus-
tained indefinitely in the absence of that of the brain.
By a series of impulses due to the solidarity of the

3l6 LIFE AND DEATH.

grouping of the parts, the injury received by the
brain affects by repercussion the other organs, and
leads in the long run to the arrest of elementary life
in all the anatomical elements. The death of the
whole is then complete.

Doctors have therefore a two-fold reason for saying
that the brain may cause death. The death of the
brain suppresses the highest manifestation of life, and,
in the second place, by a more or less remote counter
stroke, it suppresses life in all the rest of the system.

Death is a Process. — Besides, the fact is general.
The death of one part always involves the death of
the rest — i.e.^ universal death. A living organism
cannot be at the same time alive and a cemetery. The
corpses cannot exist side by side with the living
elements. The dead contaminates the living, or in
some other way involves it in its ruin. Death is
propagated ; it is a progressive phenomenon which
begins at one poirft and gradually is extended to the
whole. It has a beginning and a duration. In other
words, the death of a complex organism is a process.
And further, the end of a simple organism, of a
protozoan, of a cell, is itself a process infinitely
more shortened.

The very perfection of the organism is therefore the
cause of its fragility. It is the degree of solidarity of
the parts one with another which involves the one set
in the catastrophe of the rest, just as in a delicate
piece of mechanism the derangement of a wheel brings^
nearer and nearer the total breakdown. The im-
portant parts, the lungs, the heart, the brain, suffer no
serious alteration without the reflex being felt through-
out. But there are also wheels less evident, the
integrity of which is scarcely less necessary.

tHE PROCESS OF DEATH. 317

The Solidarity of the Anatomical Elements. — The
cause of the mortal process — i.e., of the extension and
the propagation of an initial destruction — is therefore
to be found in the solidarity of the parts of the
organism. The closer it is the greater do the chances
of destruction become, for the accident which has
happened to one will by repercussions affect the
others.

Now the solidarity of the parts of the organism
may be carried out in two ways ; there is a humoral
solidarity and a nervous solidarity.

Humoral Solidarity. — Humoral solidarity is realized
by the mixture of humours. All the liquids of the
organism which have lodged in the interstices of the
elements and which soak the tissues, are in contact
and in relation of exchange one with another, and
through the permeable wall of the small vessels they
are in relation with the blood and the lymph.

All the liquid atmospheres which surround the
cells and form their ambient medium have inter-
communication. A change having taken place in one
cellular group, and therefore in the corresponding
liquid, modifies the medium of the further or nearer
groups, and therefore these groups themselves.

Nervous Solidarity. — But the real instrument of the
solidarity of the part is the nervous system. Thanks
to it in the living machine the component activities of
the cellular multitude restrain and control one another.
Nervous solidarity makes of the complex being not a
mob of cells, but a connected system, an individual in
which the parts are subordinated to the whole and the
whole to the parts ; in which the social organism has
its rights just as the individual has his rights. The
whole secret of the vital functional activity of the

3l8 LIFE AND DEATH.

complex being is contained in these two factors : — the
independence and the subordination of the elementary-
lives. General life is the harmony of the elementary
lives, their symphony.

Independence and Subordination of the Anatomical
Elements. — The independence of the anatomical ele-
ments results from the fact that they are the real
depositaries of the vital properties, the really active
components. On the other hand the subordination of
the parts to the whole is the very condition of the
preservation of form in animals and plants. The
architecture which is characteristic of them, the
morphological plan which they realize in their
evolutive development which they are ever preserving
and repairing, form a striking proof of this. This
dependence in no way contradicts the autonomy of
the elements. For when with Claude Bernard and
Virchow we study the circumstances we see that
the element accommodates itself to the organic
plan without violence to its nature. It behaves
in its natural place as it would behave elsewhere,
if elsewhere it were to meet around it the
same liquid medium which at once is a stimulant
and a food. This at least is the conclusion we
may draw from experiments on transplanting, or
on animal and vegetable grafting. Neither the
neighbouring elements, nor the whole system act on it
at a distance by a kind of mysterious induction,
according to the ideas of the vitalists, in order to
regulate the activity of the element. They contribute
solely to the composition of the liquid atmosphere
which bathes it. They intervene in order to provide
it with a certain environment whose very characteristic
physical and chemical constitution regulates its

THE PROCESS OF DEATH. 319

activity. This constitution may be some day imitated
by the devices of experiment. When that result is
achieved the anatomical element will live in isolation
exactly as it lives in the organic association, and the
mysterious bond which causes its solidarity with the
rest of the economy will become intelligible. In fact,
we may defer more or less the maturity of this
prophecy, but there is no doubt that we are daily
nearing its fulfilment.

The general life of the complex being is therefore
the more or less perfect synergy, the ordered process of
elementary lives. General death is the destruction of
these partial lives. The nervous system, the instru-
ment of this harmony of the parts, represents the.
social bond. It keeps most of the partial elements
under its sway, and is thus the intermediary of their
relations. The closer this dependence, the higher the
development of the nervous apparatus, and the better,
also, is assured the universal solidarity and therefore
the unity of the organism. Cellular federation
assumes the characteristic of a unique individuality
in proportion to the development of this nervous
centralization. With an ideal perfect nervous system
the correlation of the parts would also attain per-
fection. As Cuvier said : " None could experience
change without a change in the rest."

But no animal possesses this extreme solidarity of
the parts of the living economy. It is a philosopher's
dream. It is the dream of Kant, to whom the perfect
organism would be "a teleological system," a system
of reciprocal ends and means, a sum total of parts
each existing for and by the rest, for and by the
whole. An organism so completely connected would
be unlikely to live. In fact, living organisms show a

320 LIFE AND DEATH.

little more freedom in the interplay of their parts.
Their nervous apparatus fortunately does not attain
this imaginary perfection ; their unity is not so
rigorous. The idea of individuality, of individual
existence, is therefore not absolute but relative.
There are all degrees of it according to the develop-
ment of the nervous system. What the man in the
street and the doctor himself understand by death is
the situation created by the stopping of the general
vi^heels, the brain, the heart, and the lungs. If the
breath leaves no trace on the glass held to the mouth,
if the beating of the heart is no longer perceptible by
the hand which touches or the ear which listens, if the
movement and the reaction of sensitiveness have
ceased to be manifest, these signs make us conclude
that it is death. But this conclusion, as we have said
before, is a prognostic rather than a judgment of fact.
It expresses the belief that the subject will certainly
die, and not that it is from this moment dead. To
the physiologist the subject is only on the way to die.
The process has started. The only real death is
when the universal death of all the elements has been
consummated.

CHAPTER III.

PHYSICAL AND CHEMICAL CHARACTERS OF CEL-
LULAR DEATH. NECROBIOSIS. GROWING OLD.

Characteristic of elementary life— Changes produced by death
in the composition and the death of the cell— Schlemm ;
Loew ; Bokorny ; Pfliiger ; A. Gautier ; Duclaux— The
processive character of death — Accidental death— Necro-
biosis—Atrophy— Degeneration— So-called natural death —
Senescence— Metchnikoffs theory of senescence — Objec-
tions.

Elementary death is nothing but the suppression
in the anatomical elements of all the phenomena of
vitality.

Characteristics of Elementary Life. — The char-
acteristic features of elementary life have been
sufficiently fixed by science. First of all, there is
morphological unity. All the living elements have an
identical morphological composition. That is to say
that life is only accomplished and sustained in all its
fulness in organic units possessing the anatomical
constitution of the cell, with its cytoplasm and its
nucleus, constituted on the classical type. In the
second place, there is chemical unity. The constituent
matter, the matter of which the cell is built up, diverges
but little from a chemical type — a proteid complex,
with a hexonic nucleus, and from a physical model
which is an emulsion of granulous, immiscible liquids,
of different viscosities. The third character consists in

321

•322 LIFE AND DEATH.

the possession of a specific form acquired, preserved,
and repaired by the element. The fourth character,
and perhaps the most essential of all, is the property
of growth or nutrition with its consequence, namely, a
relation of exchanges with the external medium,
exchanges in which oxygen plays considerable part.
Finally, there is a last property, that of reproduction,
which in a certain measure is a necessary consequence
of the preceding, — i.e., of growth.

These five vital characters of the elements are most
in evidence in cells living in isolation, in microscopical
beings formed of a single cell, protophytes and
protozoa. But we find them also in the associations
formed by the cells among one another — i.e., in
ordinary plants and animals, multicellular complexes,
called for this reason metaphytes and metazoa. Free
or associated, the anatomical elements behave in the
same way — feed, grow, breathe, digest in the same
manner. As a matter of fact, the grouping of the
cells, the relations, proximity and contiguity, which
they assume, introduce some variants into the ex-
pression of the common phenomena ; but these slight
differences cannot disguise the essential community
of the vital processes.

The majority of physiologists, following Claude
Bernard, admit as valent and convincing the proof that
the illustrious experimenter furnished of this unity
of the vital processes. There are, however, a few
voices crying in the wilderness. M. Le Dantec is one.
In his new theory of life he amplifies and exalts the
differences which exist between the elementary life of
the proteids and the associated life of the metazoa.
In them he can see nothing but contrasts and
deviations.

PHYSICAL AND CHEMICAL CHARACTERS. 323

If this is elementary life, let us ask what is
elementary death — i.e.^ the death of the cell. And in
this connection let us ask the questions which we have
to examine in the case of animals high in organiza-
tion, and of man himself What are the characteristics
of elementary death ? When the cell dies, is its death
preceded by a growing old or senescence? What are
the preliminary signs and the acknowledged symptons?

Changes Produced by Death. — The state of death is
only truly realized when the fundamental properties
of living matter enumerated above have entirely
disappeared. We must follow step by step this dis-
appearance in all the anatomical elements of the
metazoan.

Now the properties of the cell are connected with
the physical and chemical organization of living
matter. For them to disappear entirely, this organ-
ization must be destroyed as far as all that is essential
in it is concerned. We cannot admit with the
vitalists that there is any material difference between
the dead and the living, and that only an immaterial
principle which has escaped into the air distinguishes
the corpse from the animated being. In fact, the
external configuration may be almost preserved, and
the corpse may bear the aspect and the forms of the
preceding state. But this appearance is deceptive.
Something in reality has changed. The structure,
the chemical composition of the living substance,
have undergone essential changes. What are these
changes ?

Physical Changes. — Certain physiologists have
endeavoured to determine them. Klemm, a botanist,
pointed out in 1895 the physical changes which
characterize the death of vegetable cells — loss of

324 LIFE AND DEATH.

turgescence, fragmentation of the protoplasm, the
formation of granules, and the appearance of vacuoles.

Chemical CJinnges. — O. Loew and Bokorny laid
great stress in 1886 and 1896 on the chemical changes.
The living protoplasm according to them is an
unstable proteid compound. A slight change would
detach from the albuminoid molecule a nucleus with
the function of aldehyde, and at the same time would
transform an amido-group into an amido-group. This
would suffice for the transition of the protoplasm from
the living to the dead state. This theory is based on
the fact that the compounds which exercise a toxic
action on the living cell, without acting chemically on
the dead albumin, are easily fixed by the aldehydes ;
and on the fact that many of them, which attack
simultaneously the living albuminoids and the dead
albumin, easily combine with the amido-group.

E. Pfluger, a celebrated German scientist, has
considered living matter as an albumin spontaneously
decomposable, the essential nucleus of which is formed
by cyanogen. Its active instability would be due to
the penetration into the molecule of the oxygen which
fixes on the carbon and separates it from the nitrogen.
Armand Gautier has not confirmed this view.
Duclaux (1898) has stated that the difference between
the living and the dead albumin would be of a stereo-
chemical order.

Progressive Character of Death. Accidental Death.
— We have seen that in general the disappearance of
the characteristics of vitality is not instantaneous, at
least in the natural course of things, in complex organ-
isms. It is the end of a more or less rapid process. But
death is not instantaneous in the isolated anatomical
element any more than it is in the protozoan or

PHYSICAL AND CHEMICAL CHARACTERS. 325

protophyte. We must have recourse to very violent
devices of destruction to kill the cell at a blow, to
leave absolutely nothing of its organization- existing.
The protoplasm of yeast when violently crushed by
Biichner still possessed the power of secreting soluble
ferments. A powerful action, a very high temper-
ature, is necessary to obtain the result. A fortiori,
the difficulty increases in the case of complex organ-
isms, all of whose living elements cannot be attacked
at the same moment by the destructive cause. A
mechanical action, capable of destroying at one blow
all the living parts of a complex being, of an animal,
of a plant, must be of almost inconceivable power.
The blow of a Nasmyth hammer would not be strong
enough.

The chemical alteration produced by a very toxic
substance distributed throughout the blood, and thus
brought into contact with each element, would produce
a disorganization which, however rapid it were, could
not be called instantaneous. And the same holds
good of physical agents.

But these are not the processes of nature under
normal circumstances. They are accidents or devices.
We shall leave on one side their consideration and
we shall only deal here with the natural processes of
the organism.

Imagine it placed in a medium appropriate to its
needs and following out without intervening com-
plications the evolution assigned to it by its
constitution. Experiment tells us that this natural
evolution in every case known to us ends in death.
Death supervenes sooner or later. For beings higher
in organization, which we can bring into closer and
closer resemblance to man, we find that they die of

326 LIFE AND DEATH.

disease, by accident, or of old age. And as disease
is an accident, we may naturally ask if what we call
old age is not also a disease.

However that may be, the mortal process, being
never instantaneous, has a duration, a beginning, a
development, an end — in a word, a history. It
constitutes an intermediary phase between perfect
life and certain death.

Necrobiosis. Atrophy. Degeneration. — The process
according to the circumstances may be shortened or
prolonged. When death is the result of violence
events are precipitated. The physical and chemical
transformations of the living matter constitute a kind
of acute alteration called by Schultze and Virchow
necrobiosis. According to the pathologists, there are
two kinds of necrobiosis : — that by destruction, by
simple atrophy, which causes the anatomical elements
to disappear gradually without undergoing appreci-
able modifications ; and necrobiosis by degeneration,
which transforms the protoplasm into fatty matter
into calcareous matter, into granulations (fatty de-
generation, calcification, granulous degeneration).
There is no disagreement as to the causes of this
necrobiosis. They are always accidental ; they '
originate in external circumstances: — the insufficiency
of the alimentary materials, of water, of oxygen ; the
presence in the medium of real poisons destroying
the organized matter ; the violent intervention of
physical agents, heat, electricity ; the reflex on the
composition of the cellular atmosphere of a violent
attack on some essential organ, the heart, the lungs,
the kidneys.

Senescence. Old Age. — In a second category we
must place the mortal processes, slow in their move-

PHYSICAL AND CHEMICAL CHARACTERS. 32/

ment, in which we cannot see the intervention of
clearly accidental and abnormal disturbing agents.
Death appears to be the termination of a breaking-up
proceeding by insensible degrees in consequence of the
progressive accumulation of very small inappreciable
perturbations. This slow breaking up is adequately
expressed by the term — growing old, or senescence.
The alterations by which it is betrayed in the cell are
especially atrophic^ but they are also accompanied,
however, by different forms of degeneration. An
extremely important question arises on this subject,
and that is whether the phenomena of senility have
their cause in the cell itself, if they are inevitably
found in its organization, and therefore if old age and
death are natural and necessary phenomena. Or, on
the other hand, should we consider them as due to a
progressive alteration of the medium, the character of
which would be accidental although frequent or
habitual ? This, in a word, is the problem which has
so often engaged the attention of philosophical
biologists. Are old age and death natural and
inevitable phenomena?

The recent experiments of Loeb and Calkins, and
all similar observations, tend to attribute to the
phenomenon of growing old the character of a
remediable accident. But the remedy has not been
found, and the animal finally succumbs to these slow
transformations of its anatomical elements. We then
say that it dies of old age.

Metchnikoff's Theory of Senescence. Objections.—^
Metchnikoff has proposed a theory of the mechanism
of this general senescence. The elements of the
conjunctive tissue, phagocytes, macrophages, which
exist everywhere around the specialized and higher

22

328 LIFE AND DEATH.

anatomical elements would destroy and devour them
as soon as their vitality diminishes, and would take
their place. In the brain, for example, it would be
the phagocytes which, attacking the nervous cellules,
would disorganize the higher elements, incapable of
defending themselves. This substitution of the con-
junctive tissue, which only possesses vegetative pro-
perties of a low order, for the nervous tissues, which
possesses very high vegetative properties, results in
an evident breaking-up. The gross element of
violent and energetic vitality stifles the refined and
higher element.

This expulsion is a very real fact. It constitutes
what is called senile sclerosis. But the active role
attributed to it by Metchnikoff in the process of
degeneration is not so certain. An expert observer
in the microscopic study of the nervous system, M.
Marinesco, does not accept this interpretation as far
as the senescence of the elements of the brain is con-
cerned. Diminution of tl:\e cell, the decrease in the
number of its stainable granulations, chromatolysis,
the formation of inert, pigmented substances — all
these phenomena which characterize the breaking-up
of the cerebral cells would be accomplished, according
to this observer, without the intervention of the
conjunctive elements, the phagocytes.

The characteristic of extensive and progressive
process presented by death necessitates in a com-
plex organism, which is a prey to it, the existence
side by side of living and dead cells. Similarly, in
the organism which is growing old, there are young
elements and elements of every age side by side with
senile elements. As long as the disorganization of
the last has not gone too far, they may be rejuvenated.

PHYSICAL AND CHEMICAL CHARACTERS. 329

All we have to do is to restore to them an appropriate
ambient medium. The whole question is one of
knowing and being able to realize, for this or that
part which we wish to reanimate and to rejuvenate,
the very special or very delicate conditions that this
medium must fulfil. As we have said, success is
attained in this respect as far as the heart is con-
cerned, and this is why we are able to reanimate and
to" revive the heart of a dead man. It is hoped that
ideas along these lines will extend with the progress
of physiology.

After this sketch of the conditions and of the
varieties of cellular death we must return to the
essential problem which is engaging the curiosity of
biologists and philosophers. Is death unavoidable,
inevitable? Is it the necessary consequence of life
itself, the inevitable issue, the inevitable end ?

There are two ways of endeavouring to solve this
question of the inevitability of death. The first is to
examine popular observation, practised, so to speak,
unintelligently and without special precautions. The
second is to analyze everything we know relative to
the conditions of elementary life.

CHAPTER IV.

THE APPARENT PERENNITY OF COMPLEX
INDIVIDUALS.

Millenary trees — Plants with a definite rhizome — Vegetables
reproduced by cuttings — Animal colonies — Destruction due
to extrinsic causes — Difficulty of interpretation.

Popular opinion teaches us that living beings have
only a transient existence, and as a poet has said:
" Life is but a flash between two dark nights." But,
on the other hand, simple observation shows us, or
appears to show us, beings whose duration of exist-
ence is far longer, and practically illimitable.

Millenary Trees. — We know of trees of venerable
antiquity. Among these patriarchs of the vegetable
world there is a chestnut tree on Mount Etna which
is ten centuries old, and an ivy in Scotland which is
said to be thirty centuries old. Trees of 5000 years
old are not absolutely unknown. We may mention
among those of that age the famous dragon tree^ at
Orotava, in the island of Teneriffe. Two other
examples are known in California — the pseudo-cedar,
or Tascodiuin, at Sacramento, and a Sequoia gigantea.
We know that the olive tree may live 700 years.
There are cedars 800 years old and oaks of the age of
1,500 years.

Plants ivith a Rhizome. — Vegetable species of

^ Lately destroyed in a storm. [Tr.]

PERENNITY OF COMPLEX INDIVIDUALS. 33I

almost unlimited duration of life are known to
botanists. Such, for instance, are plants with a
definite rhizome, such as colchicum. Autumnal
colchicum has a subterranean root, the bulb of
which pushes out every year fresh axes for a new
bloom ; and as each of these new axes stretches out
an almost constant length, a botanist once set himself
the singular problem of discovering how long it would
take such a foot, if suitably directed, to travel round
the world.

Vegetables Reproduced by Cntthigs. — Vegetables re-
produced by slips furnish another example of living
beings of indefinite duration. The weeping willows
which adorn the banks of sheets of water in the parks
and gardens throughout the whole of Europe have
sprung, directly or indirectly, from slips of the first
Salix Babylonica introduced to the West. May it not
be said that they are the permanent fragments of that
one and the same willow?

Anmial Colonies. — These examples, as well as those
furnished to zoologists by the consideration of the
polypi which have produced by their slow growth the
reefs, or atolls, of the Polynesian seas, do not, how-
ever, prove the perennity of living beings. The
argument is valueless, for it is founded upon a con-
fusion. It turns on the difficulty that biologists
experience in defining the individual. The oak and'
the polypus are not simple individuals, but associa-
tions of individuals, or, to use Hegel's expression,
the nations of which we see the successive genera-
tions. We give to this succession of generations a
unique existence, and our reasoning comes to this,
that we confer on each present citizen of this social
body the antiquity which belongs to the whole.

332 LIFE AND DEATH.

Destruction of the Social Individual due to Extrinsic
Causes. — As for the destruction, the death of this
social individual, of this hundred-year-old tree, it
seems indeed that there is no ground for considering
it a natural necessity. We find the sufficient reason
of its usual end in the repercussion on the individual
of external and contingent circumstances. The cause
of the death of a tree, of an oak many centuries old,
is to be found in the ambient conditions, and not in
some internal condition. Cold and heat, damp and
dryness, the weight of the snow, the mechanical
action of the rain, of hail, of winds unchained, of
lightning; the ravages of insects and parasites —
these are what really work its ruin. And further,
the new branches, appearing every year and increas-
ing the load the trunk has to bear, increase the
pressure of the parts, and make more difficult the
motion of the sap. But for these obstacles, external,
so to speak, to the vegetable being itself, it would
continue indefinitely to bloom, to fructify, and as
each spring returned to show fresh buds.

Difficulty of Interpretation. — In this as in all other
examples we must know the nature of the beings that
we see lasting on and braving the centuries. Is it the
individual? Is it the species? Is it a living being,
properly so called, having its unity and its in-
dividuality, or is it a series of generations succeeding
one another in time and extending in space? In a
word, the question is one of knowing if we have to do
with a real tree or with a genealogical tree. We are
just as uncertain when we deal with animals. What
is the being that lasts on — a series of generations or
an individual ? This doubt forbids us to draw any
conclusion from the observation of complex beings.

PERENNITY OF COMPLEX INDIVIDUALS. 333

We must therefore return from them to the elementary
being, and we must examine it from the point of view
of perennity or of vital decay. Let us then ask the
questions that we have already examined with refer-
ence to animals high in organization and to man
himself. Is the death of the cell an inevitable char-
acteristic? Are there any cells, protophytes, protozoa,
which are immortal ?

CHAPTER V.

THE IMMORTALITY OF THE PROTOZOA.

Impossibility of life without evolution — Law of increase and
division — Immortality of the protozoa — Death, a pheno-
menon of adaptation which has appeared in the course of
the ages — The infusoria— The death of the infusoria — Two
kinds of reproduction — The caryogamic rejuvenescence of
Maupas — Calkins on rejuvenescence — Causes of senescence
— Impossibility of life without evolution.

We take into account, a priori, the conditions that
must be fulfilled by the monocellular being in order
to escape the inevitability of evolution, of the succes-
sion of ages, of old age, and of death. It must be
able indefinitely to maintain itself in a normal regime,
without changing, without increasing, maintaining its
constant morphological and chemical composition, in
an environment vast enough for it to be unaltered by
the borrowings or the spendings resulting from its
nutrition — i.e., it must remain constant in the presence
of the constant being. We might conceive of a
nutrition perfect enough, of exchanges exact enough,
and regular enough, for the state of things to be
indefinitely maintained. This would be absolute
permanence realized in the vital mobility.

The Law of GroivtJi and Division. — This model of
a perfect and invariable machine does not exist in
nature. Life is incompatible with the absolute per-

334

THE IMMORTALITY OF THE PROTOZOA. 335

manence of the dimensions and the forms of the living
organism.

In a word, it is a rigorous law of living nature that
the cell can neither live indefinitely without growth,
nor grow indefinitely without division.

Why is this so? Why is there this impossibility
of a regular regime in which the cell would be main-
tained in magnitude without diminution or increase?
Why has nutrition as a necessary consequence the
growth of the element? This is what we do not
positively know.

Things are so. It is an irreducible fact, peculiar to
the protoplasm, a characteristic of the living matter
of the cell. It is the fundamental basis of the pro-
perty of generation. That is all we can say about it.
Real living beings have therefore inevitably an evolu-
tion. They are not unchangeable. In its simple form
this evolution consists in the fact that the cell grows,
divides, and diminishes by this division, begins the
upward march which ends in a new division. And
so on.

Immortality of the Protozoa. — It may happen, and
it does happen in fact, that this series of acts is
repeated indefinitely at any rate unless an accidental
cause should interrupt it. The animal thus describes
an indefinite curve, constituted by a series of indenta-
tions, the highest point of which corresponds to the
maximum of size, and the lowest point to the
diminution which succeeds the division. This state of
things has no inevitable end if the medium does not
change. The being is immortal.

In fact, the compound beings of a single cell, proto-
phytes and protozoa, the algae and the unicellular
mushrooms, at the minimum stage of differentiation,

336 LIFE AND DEATH.

escape the necessity of death. They have not, as
Weismann remarks, the real immortality of the gods
of mythology, who were invulnerable. On the con-
trary, they are infinitely vulnerable, fragile, and
perishable; myriads die every moment. But their
death is not inevitable. They succumb to accidents,
never to old age.

Imagine one of these beings placed in a culture
medium favourable to the full exercise of its activities,
and, moreover, wide enough in its extent to be un-
affected by the infinitely small quantities of material
which the animal may take from it or expel into it.
Suppose, for example, it is an infusorian in an ocean.
In this invariable medium the being lives, increases,
and grows continually. When it has reached the
limits of a size fixed by its specific law, it divides into
two parts, which are indistinguishable the one from
the other. It leaves one of its halves to colonize in its
neighbourhood, and it begins its evolution as before.
There is no reason why the fact should not be re-
peated indefinitely, since nothing is changed, either
in the medium or in the animal.

To sum up. The phenomena which take place in
the cell of the protozoan do not behave as a cause of
check. The medium allows the organism to revictual
and to discharge itself in such a way and with such
perfection that the animal is always living in a regular
regime, and, with the exception of its growth and
later on of its division, there is nothing changed
in it.

Death a Phenomenon of Adaptation — It appeared in
the Course of the Ages. — This immortality belongs in
principle to all the protista which are reproduced by
simple and equal division. If it be remarked that

THE IMMORTALITY OF THE PROTOZOA. 337*

these rudimentary organisms endowed with perennity
are the first living forms which have shown them-
selves on the surface of the globe, and that they have
no doubt preceded many others — the multicellular,
for instance, which are liable, on the contrary, to
decay — the conclusion is obvious: — Life has long
existed without death. Death has been a pheno-
menon of adaptation which has appeared in the
course of the ages in consequence of the evolution of
species.

The Death of Inftisoria. — We may ask ourselves at
what moment in the history of the globe, at what
period of the evolution of its- fauna, this novelty,
death, made its appearance. The celebrated experi-
ments of Maupas on the senescence of the infusoria
seem to authorize us to give a precise answer to this
question. By means of these experiments we are
led to believe that death must have appeared
at the same time as sexual reproduction. Death
became possible when this process of generation
w^as established, not in all its plenitude, but in its
humblest beginnings, under the rudimentary forms
of unequal division and of conjugation. This
happened when the infusoria began to people the
waters.

The Two Modes of Multiplication. — Infusoria are, in
fact, capable of multiplication by simple division.
It is true to say that in addition to this resource, the
only -one which interests us here, because it is the
only one which confers immortality, they possess
another. They present and exercise under certain
circumstances a second mode of reproduction, caryo-
gamic conjugation. It is a rather complicated
process in its detail, but it is definitively summed up

338 LIFE AND DEATH.

as the temporary pairing of two individuals, which
are otherwise very much aHke, and which cannot be
distinguished as male and female. They become
closely united on one of their faces; they reciprocally
exchange a semi-nucleus which passes into the cm
joint individual; and then they separate. yBut
infusoria can be prevented from this conjunction by
regularly isolating them immediately after their birth.
Then they grow, and are constrained after/a lapse of
time to divide according to the first method.

Maupas has shown that the infusona could not
accommodate themselves to this regime indefinitely ;
they could not go on dividing for ever. After a
certain number of divisions th/y show signs of
degeneration and of evident/ decay. The size
diminishes, the nuclear orga/is become atrophied,
all the activities fail, and 1/ne infusorian perishes.
It succumbs to this kind ai senile atrophy unless it
is given an opportunity of/conjugation with another
infusorian in the same flight. In this act it then
derives new strength, ft grows larger, attains its
proper size, and builds up its organs once more.
Conjugation gives it life, youth, and immortality.

A limcntary Rejuvenescence. — Recent observations
due to Mr. G. N. (lalkins, an American biologist,
and confirmed by qther investigators, have shown
that this method of rejuvenescence is not the only
one, and is not even the most efficacious. Conju-
gation has no mysterious, specific virtue. The
infusoria need not be married in order to be
rejuvenated. It is sufficient to improve their food.
In the case of the " tailed " Paramecium we may
substitute beef broth and phosphates for conjuga-
tion. Calkins observed 665 consecutive generations

THE IMMORTALITY OF THE PROTOZOA. 339

without blemish, without exhaustion, and without
any sign of old age. Plenty of food and. simple
drugs have successfully resisted senility and the
train of atrophic degenerations which it involves.

Causes of Senescence. — As for the causes of senes-
cence which have been remedied with such success,
they are not exactly known. Calkins thinks that
senescence results from the progressive losses to the
organism of some substance essential to life. Con-
jugation or intensive alimentation would act by build-
ing up again this necessary compound. G. Loisel
believes on the contrary that it is a matter of the
progressive accumulation of toxic products due to a
kind of alimentary auto-intoxication.

CHAPTER VI.

LETHALITY OF THE METAZOA AND OF
DIFFERENTIATED CELLS.

Evolution and death of metazoa. — Possible rejuvenescence of
the differentiated cells by the conditions of the medium.
— Conditions of the medium for immortal cells. — The
immortal elements of metazoa.— The element in accidental
and remediable death. — Somatic cells and sexual cells.

Evolution and Death of Metazoa. — We have seen
that the infusoria are no longer animals in which
material exchanges take place with sufficient perfec-
tion, and in which cellular division, the consequence
of growth, is produced with sufficient precision and
equality for life to be carried on indefinitely in
a perfect equilibrium in the appropriate medium
without alteration or check. A fortiori we no
longer find the perfect regularity of nutritive
exchange in the classes above them. In a word,
starting from this inferior group, there are no
animated beings in the state of existence which
Le Dantec calls " condition i° " of manifested life ? "
Living matter, instead of being continually kept
identical in conditions of identical media, is modified
in the course of existence. It becomes dependent on
time. It describes a declining trajectory; it ex-
periences evolution, decay, and death. Thus the

340

LETHALITY OF THE META^OA. 34I

fundamental condition of invariable youth and
of immortality fails in all metazoa. The vital
wastes accumulate in all through the insufficiency
or the imperfection of nutritive absorption or of
excretion. Life decays ; the organism progressively
alters, and thus is constituted that state of de-
crepitude by atrophy or chemical modification
which we call senescence, and which ends in death.
To sum up, old age and death may be attributed to
cellular differentiation.

Possible Alimentary Rejuvenescence of the Differ-
entiated Cells — Conditions of Medium. — We must add,
however — as the teaching of experiments in general
and in particular as the teaching of the experiments
of Loeb and of Calkins — that a slight change of the
environment, made at the right time, is capable of
re-establishing equilibrium and of completely re-
juvenating the infusorian. Senescence has not in
this case a definitive any more than an intrinsic
character; a modification in the composition of the
alimentary medium will successfully resist it. If we
are allowed to generalize this result, it may be said
that senescence, the declining trajectory, the evolu-
tion step by step down to death, are not for the
cells considered in isolation an inevitable and essen-
tially inherent in the organism, and a rigorous con-
sequence of life itself They preserve an accidental
character. In senescence and death there is no
really natural, internal cause, inexorable, and irre-
mediable, as was claimed in the past by J. Muller,
and more recently by Cohnheim in Germany and
Sedgwick Minot in America.

Conditions of the Medium for Immortal Cells. — As
for the cells which are less differentiated, the proto-

342 LIFE AND DEATH,

phytes and the protozoa situated one degree lower in
the scale than the infusoria, we must admit the
possibility of that perfect and continuous equilibrium
which would save them from senile decrepitude.
And it is quite understood that this privilege re-
mains subordinated to the perfect constancy of the
appropriate medium. If the latter changes, the
equilibrium is broken, the small insensible per-
turbations of nutrition accumulate, vital activity
decays, and in sole consequence of the imperfection
of the extrinsic conditions or of the medium, the
living being finds itself once more dragged down to
decay and to death.

Immortal Elements of the Metazoa. — All the pre-
ceding facts and considerations refer to isolated cells,
to monocellular beings. But, and this is what makes
these truths so interesting, they may be extended to
all cells grouped in collectivity — i.e., to all the
animals and living beings that we know. In the
complicated edifice of the organism, the anatomical
elements, at any rate the least differentiated, would
have a continual brevet of immortality. Generally
speaking, this would be the case for the egg, for the
sexual elements, and perhaps, too, for the white
globules of the blood, the leucocytes. And, further,
around each of these elements must be realized the
invariably perfect medium which is the necessary
condition. This does not take place.

Elements in Accidental and Remediable Death. — As
for the other elements, they are like the infusoria,
but without the resource of conjugation. The
ambient medium becomes exhausted and intoxicated
around each cell, in consequence of the accidents
which happen to the other cells. Each therefore

LETHALITY OF THE METAZOA. 343

undergoes progressive . decay, and finally they
perish — the decay and destruction being perhaps
in principle accidental, but, irl fact, they are the
rule.

The different anatomical elements of the organism
are more or less sensitive to those perturbations which
cause senescence, necrobiosis, and death. There are
some more fragile and more exposed. Some are
more resisting, and finally, there are some which
are really immortal. We have just said that the
sexual cell, the ovum, is one. It follows that the
metazoan, man for instance, cannot entirely die.
Let us consider one of these beings. Its ancestors,
so to speak,^ have not entirely disappeared ; each has
left the fertile egg, the surviving element from which
has issued the being of which we speak ; and when
it in its turn has developed, part of that ovum has
been placed in reserve for a new generation. The
death of the elements is not therefore universal.
The metazoan is divided from the beginning into
two parts. On the one hand are the cells destined
to form the body, somatic cells. They will die. On
the other hand are the reproductive, or germinal, or
sexual cells, capable of living indefinitely.

Somatic and Sexual Cells. — In this sense we may
say with Weismann that there are two things in
the animal and in man — the one mortal, the soma
the body, the other immortal, the germen. These
germinal cells, as in the case of the protozoa we
mentioned above, possess a conditional immortality.
They are imperishable, but on the contrary, are
fragile and vulnerable. Millions of ova are destroyed
and are disappearing every moment. They may die
by accident, but never of old age.

23

344 LIFE AND DEATH.

We now understand that if the protistae are
immortal, it is because these hving beings, reduced
to a single cell, accumulate in it the compound
characters of the somatic cell and germinal cell,
and enjoy the privilege which is attached to the
latter.

CHAPTER VII.

MAN. THE INSTINCT OF LIFE AND THE INSTINCT
OF DEATH.

Xhe miseries of humanity: i. Disease; 2. Old age. — Old age
considered as a chronic disease. — Its occasional cause. — 3.
The disharmonies of human nature; 4. The instinct of life
and the instinct of death.

Man's unhappy plight is the constant theme of
philosophies and religions. Without referring to its
moral basis, it has a physical basis due to four
causes — the physical imperfection or disharmony of
nature, disease, old age, and death — or rather of
three, for what we call old age is perhaps a simple
disease. These are the great sorrows of man, the
sources of all his woes. Disease attacks him, old age
awaits him, and death must tear him from all the
ties which he has formed. All his pleasures are
poisoned by the certain knowledge that they last
but for a moment, that they are as precarious as his
health, his youth, and his life itself.

§ Disease.

Disease, frequent, constant, and inevitable as it is,
is, however, nothing but a fact outside the natural
order. Its character is clearly accidental, and it
interrupts the normal cycle of evolution. Medical

345

346 LIFE AND DEATH.

observation teaches us, on the other hand, that the
health of the body reacts on that of the mind; and
therefore man as a whole, moral and physical, is
affected by disease. Bacon described a diseased
body as a jailer to the soul, and the healthy body as
a host. Pascal recognized in diseases a principle of
error. " They spoil our judgment and our senses."

I am not expressing a chimerical hope when I
predict that science will conquer disease. Medicine
has at last issued from the contemplative attitude
of so many centuries ; it has engaged in the
struggle, and signs of victory are already appearing.
Disease is no longer the mysterious power which it
was impossible to escape. Pasteur gave to it a body.
The microbe can be caught. In the words of
Schopenhauer, an alteration of the atmosphere so
slight that it is impossible to detect it by chemical
analysis may bring on cholera, yellow fever, the
black plague, diseases which carry off thousands of
men; and a slightly greater alteration might endanger
all life. The at once mysterious and terrifying spec-
tacle of the cholera at Berlin in 1831 had such an
effect on the philosopher that he fled in terror to
Frankfort. It has been said that this was the origin
of his pessimism, and that but for this he would have
continued to teach idealistic philosophy in some
Prussian university. L. Hartmann, another cele-
brated leader of contemporary pessimism, has also
said that disease will always be beyond the resources
of medicine. Facts have given the lie to these
sombre prognostics. The microbic origin of most in-
fectious diseases has been recognized. The discovery
of attenuated poisons and serums has diminished
their gravity. An exact knowledge of methods of

MAN. THE INSTINCT OF LIFE AND DEATH. 347

contagion has enabled us to erect against them im-
pregnable barriers. Cholera, yellow fever, the plague
knock in vain at our doors. Diphtheria, dreaded by
every mother, has partially lost its deadly character.
Puerperal fever and blindness of the new-born child
are tending to disappear. Legend tells us that
Buddha in his youth, frightened at the sight of a
sick man, expressed in his father's presence the wish
to be always in perfect health and sheltered from
disease. The King answered: "My son! you are
asking the impossible." But it is towards the
realization of this impossibility that we are on our
way. Science is repelling the attacks of disease.

§ 2. Old Age.

Old age is another sorrow of humanity. The
stage of existence in which the strength grows less
and never grows greater, and in which a thousand
infirmities appear, is not, however, a stage universal
in animals. Most of them die without our perceiving
in them any apparent signs of senile weakness. On
the other hand, some vegetables exhibit these signs.
Some trees are old; but it is in birds and mammals
that this decay, with the train of evils which accom-
panies it, becomes a very marked phase of existence.
In man to debility is added a bodily shrinkage, grey
hairs, withered skin, and the wearing out and loss of
teeth. The exhausted and atrophied organism offers
a favourable field to all intercurrent diseases and to
every cause of destruction. It is this discrepitude
which makes old age so hateful. All desire to be
old, said Cicero; and when they are old, they say
that old age has come quicker than they expected.

34^ LIFE AND DEATH.

La Bruyere expresses it in an apothegm, "We want
to grow old, and we fear old age." One would like
longevity without old age.

But can life be prolonged without senility diminish-
ing its value? Metchnikoff thinks it can. He
more or less clearly catches a glimpse of a normal
evolution of existence which would make it longer
and nevertheless exempt from senile decay.

It is remarkable that we have so few scientific data
on the old age of man, and we have still few er on
that of animals. The biologist know s no more than
the layman. The old age of the dog is betrayed by
its gait. Its coat loses its lustre, just as in disease.
The hair whitens around the forehead and the
muzzle. The teeth grow blunt and drop out. The
character loses its gaiety and becomes gloomy; the
animal becomes indifferent. He ceases to bark, and
often becomes blind and deaf.

It is admitted that senile degeneration is due to an
alteration affecting most of the tissues. The cells,
the special anatomical elements of the liver, the
kidney, and the brain are reduced by atrophy and
degeneration. At the same time, the conjunctive
woof which serves them as a support develops, on
the contrary, at the expense in a measure of the
higher elements. For this reason the tissues harden.
We know that the flesh of old animals is tough. We
know in pathology that this is happening to the
tissues. It is due to growth, to injury to the
active and important elements, to the elements of
support of the organs. They form a tissue some-
times called packed tissue, to show its secondary role
with reference to the elements which are deposited
in it. This kind of degeneration of the organs is

MAN. THE INSTINCT OF LIFE AND DEATH. 349

known as sclerosis. It constitutes the charasteristic
lesion of a certain number of chronic diseases; and
these diseases are serious, for the stifling of the
characteristic elements by the less important ele-
ments of the conjunctive or packed tissue results in
the more or less complete reduction or suppression
of the function.

The blood vessels also undergo this transformation,
and what we may call universal trouble and danger
ensue. This sclerosis of the arteries, this arterio-
sclerosis, not only deprives the walls of the blood
vessels of the suppleness and elasticity which are
necessary for the proper irrigation of the organs, but
it makes them more fragile. Thus it becomes a
cause of hemorrhage, which is a very serious matter
as far as the brain and lungs are concerned.

It is remarkable that the alteration of the tissues
during old age should be exactly similar to this.
This is inferred from the few researches that have
been made on the subject — from those of Demange
in 1886, of Merkel in 1891, and finally from the
researches of Metchnikoff himself. It is a generalized
sclerosis. As its consequence we have the lowering
of the proper activity of the organs and the danger
of cerebral hemorrhage created by arterio-sclerosis.
The transformations of the tissues in old men are
therefore summed up in the atrophy of the important
and specific elements of the tissues, and their replace-
ment by the hypertrophied conjunctive tissue. This
sclerosis, is comparable to that of chronic diseases;
it is a pathological condition. Thus old age, as we
understand it, is a chronic disease and not a normal
phase of the vital cycle.

On the other hand, if we ask ourselves what is the

350 LIFE AND DEATH.

origin of the scleroses which engender chronic
diseases, we find that they are due to the action of
various poisons, among which syphihtic poison and
the immoderate use of alcohol^ take the first place.
These are also the usual causes of senile degenera-
tion. But there must be some other, some very
general cause to explain the universality of the'
process of senescence. Metchnikoff thinks that he
has found this cause in the microbes which swarm in
man's digestive tube, particularly in the large in-
testine. Their number is enormous. Strassburger
has given an approximate calculation, but words fail
to express it. We have to imagine a figure followed
by fifteen zeros. This microbic flora is composed of
"bacilli" and of "cocci," and comprises a third of
the rejected matter. It produces slow poisons,
which, being at once reabsorbed, pass into the blood
and provoke the constant irritation from which
results arterio-sclerosis and the universal sclerosis
of old age. Instead of enjoying a healthy and
normal old age, in which the faculties of ripening
years are preserved, we drag out a diminished life,
a kind of chronic disease, which is ordinary old age.
This is due, according to Metchnikofi", to the para-
sitism and the symbiosis of microbic flora, lodged in
a part of the economy in which it finds all the con-
ditions favourable to its prolific expansion. Such is
the specious theory, held to the verge of intrepidity,
by which this investigator explains the misery of our
old age, and which inspires him with the ^dea of a
remedy. For his observations conclude with a
regime, a series of prescriptions by which the author
fancies that life may be lengthened and the evils of
old age swept from our path. The dangerous flora

MAN. THE INSTINCT OF LIFE ANI> DEATH. 35 1

must be transformed into a cultivated and selected
flora. Although the organ in question may be of
doubtful utility, and although its existence, the
legacy of atavic heredity,- must be considered as a
.disharmony of human nature, Metchnikoff does not
go so far as to propose that it should be cut away,
and that we should call in surgery to assist in making
mankind perfect ! But the rational means he pro-
poses will be endorsed by the most' judicious students
of hygiene; and their effect, if it not as wonderful
as one hopes for, cannot fail to ameliorate the
conditions of old age and make it more vigorous.

§ 3. Disharmonies in Human Nature.

Another misery in the condition of man is due to
the dissidencies of his nature — that is to say, to his
physical imperfections and the discordancies which
exist between the physiological functions and the
instincts which should regulate them.

This discordance reigns throughout the physical
organism. The body of man is not the perfect
masterpiece it was once supposed to be. It is
encumbered with annoying inutilities, with rudi-
mentary organs that have neither role nor function,
unfinished sketches which nature has left in the
different parts of his body. Such are the lachrymal
caruncle, a vestige of the third eyebrow in mammals;
the extrinsic muscles of the ear; the pineal gland of
the brain, which is only the rudiment of an ancestral
organ; the third eye, or the Cyclopean eye of the
saurians. The list is interminable. Wiedersheim has
counted in man 107 of these abortive hereditary

352 LIFE AND DEATH.

organs, the useless vestiges of organs useful to our
remote animal ancestors, atrophied in the course of
ages in consequence of modifications that have taken
place in the external medium.

These rudimentary organs are not only useless;
they are often positively harmful.

But the most serious discordance is that which
exists between the physiological functions and the
instincts which regulate them. In a well-regulated
organism slowly developed by adaptation the instincts
and the organs alike should be in relation with the
functions. All really natural acts are solicited by
an instinct, the satisfaction of which is at once a
need and a pleasure. The maternal instinct is
awakened at the proper moment in animals, and it
disappears as soon as the offspring requires no more
assistance. A craving for milk is shown in all new-
born children, and often disappears at an early age.

Nature has endowed man as well as the other
animals with peculiar instincts, destined to preside
over the different functions and to ensure their
accomplishment. And, at the same time, it has
enabled him in a measure to deceive those instincts
and to satisfy them by other means than the execu-
tion of the physiological acts with a view to which
they exist. Love and the instinct of reproduction
exist in man before the age of puberty. Canova felt
the spur of love at the age of five. Dante was in
love with Beatrice at nine; and Byron, then scarcely
seven, was already in love with Maria Duff. On the
other hand, puberty has no necessary relation to the
general maturity of the organism.

The family instinct is subject to the same aberra-
tions. Man limits the number of his children. The

MAN. THE INSTINCT OF LIFE A{^D DEATH. 353

Turks of to-day follow the ancient Greeks in the
practice of abortion. Plato approved of the custom,
and Aristotle sanctioned its general prevalence. In
the province of Canton the Chinese of the agricul-
tural classes kill two-thirds of their girl children,
and the same is done at Tahiti. All these customs
co-exist with the perfect love and tender care of the
living children.

Because of these different discordancies the physical
life of man is insufficiently regulated by nature.
Neither the physiological instinct, nor the family
instinct, nor the social instinct is, in general, suffi-
ciently imperative and precise: Hence, since the
internal impulse has not sufficient power, the neces-
sity arises for a rule of conduct exercising its influence
from without. Philosophies, religions, and legislation
have provided for this. They have regulated man's
hygiene and the carrying out of his different physio-
logical functions. Their control has, moreover, had
its hygienic side. The scientific hygiene of to-day
has inherited their role.

The idea of the fundamental perversity of human
nature is born of our cognizance of its discordancies,
unduly amplified and exaggerated. Soul and body
have been considered as distinctly discordant and
hostile elements. The body, the shroud of the soul,
the temporary host, the prison, the present source of
miseries, has been subjected to every kind of mortifi-
cation. Asceticism has treated the body and all the
innate instincts as our mortal foes.

This suspicion, this depreciation of human nature
was the great error of the mystics. This view was
as fatal as the inverse view of pagan antiquity.
The model of the perfect life according to Greek

354 LIFE AND DEATH.

philosophy is a life in conformity with nature. To
aim at the harmonious development of man was the
precept of the ancient Academy, formulated by Plato.
The Stoics and the Epicureans had adopted the same
principle. Physical nature is considered as good.
It gives us the type, the rule, and the measure. The
moral rule itself is exactly appropriate to the physical
nature. We may say that pagan morality was
hygiene, the hygiene of the soul and the body alike;
the mens sana in corpore sano gave individual and
social direction. The Rationalists, the philosophers
of the eighteenth century, such as Baron d'Holbach
and later W. Von Humboldt, Darwin, and Herbert
Spencer, have adopted analogous views. If these
views have been contested, it is because of the im-
perfections or aberrations of the natural instincts of
man. Also, if we wish to base individual family or
social morality on the natural instincts of man, it
must be specified that these instincts are to be
regularized. We must necessarily appeal from the
imperfect instincts of the present to the perfected
instincts of the future. Their perfection, moreover,
will only be a more exact approximation to the real
nature of man, and he, having avoided by the aid of
science the accidents which cause disease and senile
decrepitude, will enjoy a healthy youth and an ideal
old age.

The reason of the discrepancies between instinct
and function in man is given by the natural history
of his development. We know that man has within
him original sin — his long atavism. He has sprung,
according to the transformists, from a simian stock.
He is a cousin, the successful relation, of a type
of antinomorphic monkeys, the chimpanzees. He

. MAN. THE INSTINCT OF LIFE AND DEATH, 355

has " arrived," they have remained undeveloped.
Probably he had a common ancestor with them,
some dryopithecan of an extinct species. From that
type sprang a new type already on the way to
progress, the Pithecanthropus erectns. Finally, the
anthropoid ancestor became one fine day the father
of a scion, clearly superior to himself, a miraculously
gifted being, man. Here, then, is no sign of the slow
evolution and gradual progress, which is the doc-
trine held at present by Transformists. The Dutch
botanist De Vries has shown us, in fact, that nature
does leap: naturafacit salttis. There would thus be
crises, as it were, in the life of species. At certain
critical epochs considerable differences of a specific
value appear in their offspring. It is at one of these
critical periods in the simian life that man has
appeared as the phenomenal child of an anthropoid.
He was born with a brain and an intellect superior
to those of his humble parents; and on the other
hand, he has inherited from them an organization
which is only inadequately adapted to the new con-
ditions of existence created by the development of
his sensitiveness and his brain power. This intellect
is not proportioned to his organization, which has
not developed at the same rate; it protests against
the discordances which adaptation has not yet had
time to efface. But it will efface them in the future.

^ The Instinct of Life and the Instinct
OF Death.

The greatest discrepancy of this kind is the
knowledge of inevitable death without the instinct
which makes it longed for.

356 LIFE AND DEATH.

There are immortal animals. Man is not of the
number. He belongs, like all highly organized
beings, to the class of beings which have an end.
They die from accident or from disease. They
perish in the struggle with other animals, or with
microbes, or with external conditions. There are
certainly very few, if there are any, which die a
really natural death. And so it is with man. We
see old men gradually declining who appear to
doze gently off into the last sleep, and become
extinguished without disease, like a lamp whose oil
is exhausted. But this is in most cases only
apparently so. Besides the fact that the old age to
which they seemed to succumb is really a disease,
a generalized sclerosis, autopsy always reveals some
lesion more or less directly responsible for the fatal
issue.

Man, like all the higher animals, is therefore
subject to the law of lethality. But while animals
have no idea of death and are not tormented by the
sentiment of their inevitable end, man knows and
understands this destiny. He has with the animals
the instinct of self-preservation, the instinct of life,
and at the same time the knowledge and the fear of
death. This contradiction, this discordance, is one
of the sources of his woes.

Whether it be an accident or the regular term of
the normal cycle, death always comes too soon. It
surprises the man at a time when he has not yet
completed his physiological evolution ; hence the
aversion and the terror it inspires. " We cannot
fix our eyes on the sun or on death," said La Roche-
foucauld. The old man does not regard death with
less aversion than the young man. " He who is

MAN. THE INSTINCT OF LIFE AND DEATH. 357

most like the dead dies with most regret." Man
knows that he is not getting his- full measure.

Further, all the really natural acts are solicited
by an instinct, the satisfaction of which is a need
and a joy. The need of death should therefore
appear at the end of life, just as the need of sleep
appears at the end of the day. It would appear, no
doubt, if the normal cycle of existence were fulfilled,
and if the harmonious evolution were not always
interrupted by accident. Death would then be
welcomed and longed for. It would lose its horror.
The instinct of death would replace at the wished
for moment the instinct of life. Man would pass
from the banquet of life with no other desire. He
would die without regret, " being old and full of
days," according to the expression used in the Bible
in the case of Abraham, Isaac, and Jacob. No
doubt there are some analogies to this in the insects
which only assume the perfect form for the purpose
of procreation and immediately perish in their full
perfection. In these animals the approach of death
is blended with the intoxication of hymen. Thus
we see some of them, the ephemerae, lose at that
moment the instinct of life and the instinct of
self-preservation. They allow themselves to be
approached, taken, and seized, and make no effort
at flight.

But what is this full measure of life, which is
imparted to us ? Metchnikoff holds that the ages
attributed to several persons in the Bible are very
probable. Abraham lived 175 years, Ishmael 137,
Joseph no, Moses 120, Buffon believed in the
existence of a ratio betw^een the longevity of animals
and the duration of their growth. He fixed it at

358 LIFE AND DEATH.

7 : I. The animal whose development lasts two years
would thus have 14 years of life. This law would
give us 140 years, but the figure is too high, and
Flourens has reduced the ratio to that of 5 : i, which
would still give us 120 years. Plato died in the act
of conversation at 81; Isocrates wrote his Pana-
thena'icus at 94; Gorgias died in the full possession
of his intellect at 107.

To reach the end of the promised longevity we
must neither count on the elixir of life nor on the
potable gold of the alchemists, nor on the stone of
immortality which did not prevent its inventor,
Paracelsus, from dying at the age of 58, nor on
transfusion, nor on Graham's celestial bed, nor on
King David's gerocomy, nor on . any nostrum or
remedy. Contra vim mortis non est medicamen in
hortis, said the Salernian school. What Feuchter-
sleben said is most true, " The art of prolonging life
consists in not cutting it short," and it is a hj-giene,
but a brilliant hygiene, such as that of which
Metchnikoff traces us the future lines, which will
realize the desires of nature.

And now shall we find that physiology has solved
the enigma proposed by the Sphinx, and that it has
answered these poignant questions: — Whence do
we come ? whither do we go ? what is the end of
life ? The end of life is, to the physiologist as well
as to Herbert Spencer, the tendency towards an
existence as full and as long as possible, towards a
life in conformity with real nature freed from the
discordancies which still remain ; it is the accom-
plishment of the harmonious cycle of our normal
evolution. This ideal human nature, without dis-
cordancies, no longer vitiated as it is at present but

MAN. THE INSTINCT OF LIFE ^ND' DEATH. 35g

improved, will be the work of time and science.
Realized at last it will serve as a solid basis for
individual, family, and social morality. Healthy
youth fit for action ; prolonged, adult age, the
symbol of strength ; normal old age, wise in council,
these would have their natural places in harmonious
society. " Great actions," said one of old, *' are not
achieved by exertions of strength, or speed, or agility,
but rather by the prudence, the authority, and the
judgment which are found in a higher degree in old
age." The old age of which Cicero here speaks is
the ideal old age, regular and normal, and not the
premature, deformed, incapable and egoistic old age
which results from a pathological condition. At the
end of this full life, the old man being full of days,
will crave for the eternal sleep and will resign
himself to it with joy. . . .

Death, then, " the last enemy that shall be
destroyed," to use the expression of St. Paul, will
yield to the power of science. Instead of being
" the king of terrors," it will become after a long
and healthy life, after a life exempt from morbid
accidents, a natural and longed for event, a satisfied
need. Then will be realized the wish of the
fabulist : —

" I should like to leave life at this age, just as one
leaves a banquet, thanking the host, and departing"

Has this physiological solution of the problem of
death the virtue attributed to it by Metchnikoff?
Is it as optimistic as he thinks it is ? The instinct
of death supervening at the end of a normal and
well-fiiled cycle will no doubt facilitate to the aged
their departure on the great voyage. The wrench

24

360 LIFE AND DEATH.

will no longer exist for the dead. Will it not exist
for those who are left behind ? And since the
instinct of death can only exist about the time at
which death is expected, will the young man and
the man of ripened years look with less horror than
to-day at the 'law which cannot be escaped, when
they are in full possession of the instinct of life,
but warned of the inevitability of death ?

INDEX OF AUTHORS.

Altmann, 258

Anaxagoras, 34

Aquinas, St. Thomas, 3, 19, 248

Aristotle, 3, 15, 18, 143, 146, 307

Armstrong, 295

At water, 137

Bacon, vi., 35, 346

Baker, 233

Balbiani, 161, 165, 191, 206-7,

257
Bang, d'Yvor, 179
Barthez, 3, 19, 24
Beclard, 121
Becquerel, 278
Beijerinck, 193
Benoit, 271
Bernard, Claude, vi., 17, 27, 29,

32, 48, 50-4, 107, 109, 112, 119,

148, 150-1, 171, 190-2, 194, 197,

204, 210, 214-218, 220 et seq.,

310, 318
Bernoulli, John, 35, 73
Bert, Paul, 194
Berthelot, 91, 98, 128-130, 152,

204, 296
Berthollet, 82
Berzelius, 117
Bichat, 3, 6, 20, 22, 27-30, 35, 55,

158, 170, 198, 308
Blumenbach, 46
Boe, Sylvius Le, 35-6
Boerhaave, 35, 147, 245
Bohr, 29-30
Bokorny, 324
Boltzmann, 265
Bonnet, 23, 49

Bordeu, 3, 10, 19, 22, 24, 312
Borelli, 35
Boscovitch, 37, 248
Bose, 264
Bossuet, 1 1

361

Bouasse, 73, 264-5

Boullier, 12

Bourdeau, 237, 242

Boussingault, 149

Brandt, 257

Bravais, 282 •

Brillouin, 264, 273

Brown^ 266 et seq.

Brvicke, 44

Biichner, 325

Buffon, 46, 254, 357

Bunge, von, 3, 14

Burdon, Sanderson, 176

Busquet, 175

Biitschli, 161-2, 175

Cabanis, 245, 246

Cailletet, 272

Calkins, 327, 338

Calvert, 271

Candolle, 20

Cardan, 261

Carnot, 72-3, 89, 92 el seg., loi,

114, 121
Charpy, 237, 271
Chauffard, 3, 10, 11, 294
Chauveau, 75, 103, 108, 123, 130,

145. 213
Chevreul, 32
Chossat, 152
Cicero,. 347, 359
Clausius, 67, 88
Cohn, 191, 252
Cohnheim, 341
Colding, 58 110/e, 90
Colin, 52

Comte, 189-190, 310
Confucius, 309
Coulomb, 76, 264, 273
Crookes, 295, 302
Cuvier, 3, 6, 27-8, 105, 120, 152,

190, 198, 308, 310, 319

362

INDEX OF AUTHORS.

D'Alembert, 20, 59 note, 90, 92
Dantec, Le, 48, 52, 55 note, no,

148, 173, 198, 201, 203, 213,

216, 220, 223 et seq., 231, 246,

261, 285, 296, 340
D'Arsonval, 126
Darwin, 3, 46, 167, 258, 354
Dastre, A., 192, 198 note
Davy, Sir Humphry, 61, 80
Delafosse, 282
Delage, 208
Demange, 349
Democritus, 34, 146
Descartes, 3, 9, 35, 37, 40, 73, 91,

98
Despretz, 126
Diderot, 245, 246
Drechsel, 183
Dressel, 20

Dubois- Reymond, 44, ^%Hote, 253
Duclaux, 119, 137, 184, 324
Dufour, 297
Duguet, 264
Duhem, 62, 264, 265
Dulong, 126
Dumas, 115, 149, 151 -2

Epicurus, 35, 146

Ehrlich, 176

Errera, 52, 193-4, 237, 153, 295,

302 et seq.
Euclid, V.

Faye, 260

Feuchterslehen, 358

Flemming, 161

Flourens, 20-1, 152, 208, 306, 358

Fouillee, 242

Fromann, 161

Fuerth, 183

Galen, 25, 55, 143

Galeotti, 180

Galileo, 73, 91, 98, 197, 241, 260

Gardair, 19, 248

Gautier, A., 3, 32, 36, 39, 176,

233. 324
Gernez, 237, 288, 295 et seq.
Glisson, 27
Goethe, 170, 312
Gouy, 266, 268
Grimaud, 19

Gruber, 165, 206, 257

Guignard, 161

Guillaume, 237, 262, 264, 271, 277

Guillemin, 237

Guldberg, 83

Harbermann, 183

Haeckel, 3, 46, 164, 167, 246,

251
Hales, 43
Haller, 27

Hamilton, Sir W. Rowan, 67
Hammarsten, 180
Hartmann, 276, 346
Harvey, 43, 160
Haliy, 282
Hegel, 170, 331
Heidenhain, 3, 29, 30-1
Heitzmann, 161
Helmholtz, 44, 56, 58, 67, 90, 97,

99. 252
Helmont, van, 3, 21, 26, 33, 146,

250
Henninger, 302
Heraclitus, 34
Hertwig, 167
Hertz, 88
Hess, 91, 98
Hippocrates, 146
Him, 126
His, 46

Hlasitwetz, 183
Holbach, d', 354
Hoogewerf, 303
Hopkinson, 271
Humboldt, W. von, 354

Ingenhousz, 115
Izolet, 247

Joule, 53 note, 90-1, 93, 133 ct
seq., 143, 152

Kant, 312, 319

Kaup, 213

Kaufmann, 126

Kelvin, Lord, b},, 67, 90, 92,

251-2, 264; and the idea of

energy, 66
Kepler, 29, 241
Klemm, 323
Koelliker, 160

INDEX OF AUTHORS.

363

Kossel, 174, 179, 1 30- 1, \T)(>et seq.
Kuhne, 45
Kuhm, 216
Kuliabko, 23, 311
Kunstler, 157, 161-2, 175
Kuppfer, 161

Lammettrie, 147

Lamarck, 46

Lapparent, 284

Lapicque, 140, 145

Langley, 216

Laplace, 43, 6},, 126, 260

Laulanie, 103

Laurie, 271

La Rochefoucauld, 356

Lavoisier, 3. 28, 30, 36, 43, 65,

117, 121, 126, 128, 143, 176,

296
Lea, 216

Le Chatelier, 85, 92
Lechatelier, H. and A., 271
Lecocq de Boisbaudran, 295
Leeuwenhoek, 232
Lefevre, 126
Legallois, 21
Leydig, 161-2
Liebermeister, 136
Liebig, 26, 53 note, 117
Lilienfeld, 179, 247
Locke, 23
Lodge, 271

Loeb, 43, 167, 327, 341
,Loew, 324
Loisel, 339, 341
Lorry, 21
Longet, 52
Lowitz, 297
Loye, 192
Ludwig, 44» 215

Mach, 41, 62
Magendie, 43, 143
Magy, 37
Malgaigne, 153
Mallard, 284
Marinesco, 231, 328
Markel, 349
Maspero, 3, 234
Matthiesson, 271
Maupas, 337
Maxwell, 88

Mayer, R., 56, 58, 89, 90, 97, 99,

lOI

Mering, von, 133, 136
Metchnikoff, 327 et seq.
Miescher, 174, 179
Milne-Edwards, 152, 195
Minot, 341
Miura, 137
Mori, 145
Miiller, 20, 27, 341
Murato, 45

Naegeli, 168

Needham, 46

Newton, 58 note, 70, 90-1, 93

Noorden, van, 129, 137, 140, 210

Nussbaum, 165, 206, 215, 217

Obermeyer, 271
Osmond, 237, 271
Ostwald, 41, 62, 67, 85, 104, 237,
258, 289, 295 et seq.

Paracelsus, 26, 146, 312

Pascal, 74, 161

Pasteur, 53, 191, 222 el seq. ^ 237,

250, 288, 346
Payen, 151
Persoz, 152
Petit, 180
Pettenkofer, 210
Pfeffer, 175, 193
Pfluger, 12, 56, 135, 144, 176, 210,

213
Philpotts, 46
Pictet, 233
Pitcairn, 35
Plato, 35, 307
Plosz, 180
Poincarc, 62
Poisson, 6t,

Preyer, 192, 252 c/ seq.
Priestley, 115
Ptolemy, v.
Pythagoras, 18

Rauber, 237, 288
Raulin, 191
Regnault, 117
Reinke, 3, 32
Renan, 240
Ribbert, 208

364

INDEX OF AUTHORS.

Ribot, 247

Riche, 271

Richet, 50, 126, 140

Richter, 252

Rindfleisch, 4

Roberts- Austen, 237, 271-2

Robin, 62, 177

Rosenthal, 126

Rouvier, 160

Roux, 46, 165

Rubner, 129, 130, 140 et seq.,

210
Rumford, 80

Sabatier, 242

Sachs, 161, 194

SallesGuyon, 252

Sanderson, Burdon, 176

Scaliger, 241

Schleiden, 159

Schopenhauer, 346

Schwartz, 162

Schultze, 160, 326

Schultzenberger, 174, 162 et seq.

Secchi, 88

Seguin, 58 note, 90

Senebier, 115

Siven, 145

Spallanzani, 43, 233

Spencer, Herbert, 46, 247, 454,

358
Spring, 272

Stahl, 3, 9, 12, 35, 146
Stammreich, 137
Stead, 237

Stohmann, 129, 130, 140
Strassburger, 161, 350

Swann, 159
Swift, 262

Tait, 53 note, 66

Tamniann, 237, 253, 295 et seq.

Thales, 34

Thomson, Sir J. J., 279

Tissot, 12

Tomlihson, 264

Trembley, 22, 206

Tsuboi, 145

Tylor, 8

Verworn, 206, 252, 257
Violette, 295
Virchow, 318, 326
Voit, 119, 133 et seq., 210
Vries, de, 46, 258, 355
Vulpian, 24

Waage, 83
Waller, 47, 206
Wallerant, 282-3
Warburg, 264
Watt, 76

Weismann, 46, 167, 336, 343
Wertheim, 264
Whitman, 46
Widersheim, 351 *

Wiedermann, 264
Wiesner, 167
Willis, 36, 147
Winternitz, 126

Yung, 233

ZuNTZ, 133, 136, 210

INDEX OF SUBJECTS.

Activity, functional and vital,

lo6 et seq., 217 et seq.
Aerobia, 193
Age, old. Book v.
Albumin, 178
Albuminoids, 178
Alcohol, 136
Alimentation, 116 ei seq.
Alloys, structure of, 273
Anaerobia, 193

Animism, 6, 7, Chap. W., passim
Annealing, 275
Apposition, 291
Archeus, the, 25, 26, 33
Arginin, 187
Assimilation, law of functional,

no, 213
Atomicities, satisfied, 185
Atrophy, 326
Attraction, energy of position, 64

Balance, sheet, nutritive, 118
Beliefs, primitive, 239
Bioblasts, 253
Biophors, 167
Bias, the, 25, 33
Blood, lavage of, 192
Brain, and death, 315
Butylic ferments, 193
Butyric ferments, 193

Calorie, 125 nofe

Calorimeter, ice, 126; bomb, 128

Caprice, of Nature, 45

Cause, final, 45

Cells, 48, 147 ; somatic and sexual,

343
Cellular theory, 158 et seq.

Centrosome, 163
Chromosome, 165
Cicatrization, 287
Complex, homogeneity of the,

245
Conductibility, 26
Consciousness, in brute bodies,

244 et seq.
Continuity, principle of, 242, 247
Contractility, 26
Contraction, energy of static and

dynamic, 75
Conservation, of energy, 58 ; of

force, 58
Crystals, 200 et seq., 237 et seq.,

281 et seq.
Cytoplasm, 161 et seq.

Death, apparent, 232; senescence
of, 305 et seq. ; cellular, 321
et seq.

Decentralization, 24

Degeneration, 326

Destruction, functional, 106 ; or-
ganic, 211; of living matter,
213

Determinism, 49

Digestion, of plants and animals,
152 ^/ seq.

Direction, idea of, 16

Dominants, 33, 39, 45

Dyne, the, 71

Effort, offeree, 71

Electrolysis, 272

Energetics, 39, 56 ; laws of bio-
logical, 105 et seq, 229 ; ali-
mentary, 116 et seq.

365

366

INDEX OF SUBJECTS.

Energy, 37, Book ii., passim;
origin of idea of, 57 ; theory of,
62 ; the only objective reality,
64-5 ; and kinetic conception,
67; mechanical, 69, 73 > of con-
traction, 75 ; kinetic, 76, 83 ;
potential, 76, 83; virtual, 77 ;
of motion and position, 79;
thermal, and its measurements,
80-2 ; chemical, and its measure-
ments, 81-2; chemical and po-
tential, 83; materialization of,
84 ; transformations of, 85 et seq. ;
luminous, 86 et seq. ; conserva-
tion of, 90 et seq. ; capacity of
conversion of, 93 ; in biology,
97 ; in living beings, 99 et seq. ;
physical, 99 et seq. ; vital, 99
et seq.

Ether, 89

Equivalence, law of, 91

Excitability, 26-7

Fatigue, of metals, 264
Ferments, butylic and butyric,

193
Filiation, 250
Finalism, 43
Food, a source of energy, 118

et seq. ; thermogenic and bio-

thermogenic types of, 131 et seq. ;

dynamogenic type of, 143 ;

nitrogenous, 143 ; of animals

and plants, 153 et seq.
Force, directive, 16 ct seq., 32, 39,

48 ; vital, 45 ; an anthromorphic

notion, 71 ; and work, 74;

measurement of, 71 ; plastic,

143 ; plastic and morphoplastic

forces, 208
Form, specific, 199 et seq., 281
Fruits, acids of, 136

Gemmules, 167, 258
Generation, spontaneous, 249 et

seq. , 294 et seq.
Globulin, 178
Glyceriue, crystals of, 302
Glycogen, 108, 153 et seq.
Gramme, 71

Heat, a mode of motion, 61 ; role
of animal heat, 122 ; mechanical
equivalent of, 81 ; an excretum,
1 14 ; a degraded form of energy,
88 ; converted into work, 92

Heterogeneity, 38, 61

Histones, 179, 1^2 et seq.

Horse-power, 75

Hyaloplasm, 161

Iatro-chemistry and mechanics,

^4-5
Idioblasts, 167
Infusoria, death of, 337
Instability, 188 et seq.
Instinct, of life and death, 345

et seq.
Intussusception, 291
Invariant, mass the first, 63
Irreversibility, of vital energies,

104
Irritability, 27, 196 et seq.
Isodynamism, 142
Isomorphism, 286

Ka, the, 8

Kilogrammetre, 72, 75; per

second, 75
Kilowatt, 76
Kinetic theory, 39, 62
Knot, the vital, 21

Leucines, 183

Leucites, 163

Life, defined, 28 ; latent, 233 ;

physico-chemical theory of, 36 ;

elementary, 321
Linin, 163

Mass, and matter, 63

Materialism, 34

Matter, 37, 60, 62 ; and mass, 63 ;
two kinds of, 63 ; life of, 236
et seq. ; brute and living, 249
et seq. ; organization and con-
stitution of, 255 et seq. ; defined
as extension, 64 ; conservation
of, 65

INDEX OF SUBJECTS.

367

•' Memory," of metals, etc., 265

Merotoniy, 47

Metabolism, 117

Metazoa, evolution and death of,
340 et seq.

Meteoric cosmozoa, 252

Micellar theory, 166 et seq.

Microcosms, 163

Micro-organisms, culture of, 297

Mitomes, 169

Mobility of suirs, 260

Modality, twofold, of soul, 12

Molecules, organic, 254

Monism, 34, Chap. iv. passiin^^T,

Montpellier, the school of, 35

Motion, cause of, 71 ; kinetic con-
ception of molecular, 263

Morphogenesis, idea of, 46

Movements, internal of boilies,
262 ; Brownian, 266 et seq.

Mutability, 80, 188 et seq. ; of
living matter, 259 et seq. ; of
brute bodies, 259 et seq.

Necrobiosis, 326
Neo-vitalism, 15, 29, 32
Neurility, 27
Nickel, steels, 277
NisHS fonnatii'iis, 46
Nous, the, 18, 239
Nucleins, 179, iSo et seq.
Nucleo-albuminoids, 178; -pro-

teids, 177 et seq.
Nucleus, 163 et seq. ; hexonic, 186
Nutrition, directed, 205, 209 et

seq., 227 et seq., 290 et seq.

Organogenesis, 282
Organs, organization of, 314; death
of, 315 ; perfect, 319

Pangenks, 167

Panspermia, 252

Parameter, mass the mechanical, 63

Phenomena, vital, 44, 51, 1S9 ;

modes of motion, 61
Photography, colour, 277
Physiology, general, 56 ; cellular,

56
Plants, and immortality, 330

Plasomes, 1 67

Plurivitalism, 25

Power, 70, 75

Principle, vital, 1$ et seq.

Properties, vital, 25, 103

Proteids, 178

Protoplasm, 109 et s-eq, 175 et seq.,

231 et seq. ; life in crushed, 257

et seq.
Protozoa, immortality of, 352

et seq.
Psyche, 239
Pyrozoa, 253

Regkneration, normal, 205 ;

accidental, 206
Rei)aration, mechanism of, 2S8
Repose, functional, 109, 217 et seq.
Reserve stufT, 106 et seq., 212, 230

et seq.
Rachidian, soul, 12

Senescence, 305 et seq.
Sensibility, in brute bodies, 244
Solidarity, of anatomical elements,

humoral and nervous, 317
Soul, the, 7 et seq.
Space, 69

Specificity, vital, 48
Spireme, 165
Spongioplasm, 162
Slates, initial and final, 128
Swelling, 167
Synthesis, organizing, 109

Tagmata, 169, 175

Teleology, 43

Tetanus, bacteria of, 193

Thermogenesis, 140

Tmie, 69

Tonus, muscular, 119

Trees, and immortality, 330 et seq..

Tripod, vital, 2, 314

Turgescence, 168

Universe, the, mechanical ex-
planation of, 60; the end of the,
95

Unity, chemical, of living beings,
173 et seq., 32 1 ; morphological,
321

368

INDEX OF SUBJECTS.

Vacuoles, 113

Vibrion, seplic, 193

Vis viva, 73

Vital projierties, theory of, 29

et seq.
Vitalism, 6, 7, Chap. iii. passim ;

physico-cliemical, 29
Vitality, phenomena of, 216
Vortex, vital, 105, 120, 22g ei seq.
Vulcans, 26-7

Weight, energy of position, 64 ;
conservation of, 65 ; movement
under action of, 271 et seq.

Work, 70, 72 ; and force, 74, 77 ;
converted into heat, 92; physio-
logical, 103

Xanthic bases, 180

Zones, metastable and labile, 301

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HH Xz.vi."— Scottish Leader.

>. VII. THE CRIMINAL. By Havelock Ellis. Illustrated

•< Fourth Edition, Revised and Enlarged.

~ "The sociologist, the philosopher, the philanthropist, the novelist —

O all, indeed, for whom the study of human nature has any attraction — will

^ find Mr. Ellis full of interest and suggestiveness." — Academy.

New York : Charles Scribner's Sons.

ja

yill. SANITY AND INSANITY. By Dr.. Charles Mercier.
Illustrated.
"Taken as a whole, it is the brightest book on the physical side of
mental science published in our time." — Pall Mall Gazette-

IX. HYPNOTISM. By Dr. Albert Moll. New and Enlarged

Edition.
" Marks a step of som€ importance in the study of some difficult physio-
logical and psychological problems which have not yet received much
attention in the scientific world of England." — Nature.

X. MANUAL TRAINING. By Dr. C. M. Woodward, Directot

of the Manual Training School, St. Louis. Illustrated.
" There is no greater authority on the subject than Professor Woodward." c ^
— Manchester' Gttardian. •« J"

XL THE SCIENCE OF FAIRY TALES. By E. Sidney wS

Hartland. '2 a"

"Mr. Hartland's book will win the sympathy of all earnest students, £fz

both by the knowledge it displays, and by a thorough love and appreciation — cd

of his subject, which is evident throughout." — Spectator. W*^

XII. PRIMITIVE FOLK. By Elie Reclus. |i

"An attractive and useful introduction to the study of some aspects of S
ethnography." — Nature. 12; pq

XIII. THE EVOLUTION OF MARRIAGE. By Professor j>:
Letourneau. og^

"Among the distinguished French students of sociology, Professor Letour- ^ qq

neau has long stood in the first rank. He approaches the great study of ^j"

man free from bias and shy of generalisations. To collect, scrutinise, and a ^

appraise facts is his chief business. In the volume before us he shows these J S

qualities in an admirable degree." — Science. ^

XIV. BACTERIA AND THEIR PRODUCTS. By Dr. G. Q^
Sims Woodhead. Illustrated. Second Edition. M 5

"An excellent summary of the present state of knowledge of the subject." _Q
— Lancet. I SO^

XV. EDUCATION AND HEREDITY. By J. M. Guyau. g^^,

"It is at once a treatise on sociology, ethics, and pedagogics. It is O ©Ctf
doubtful whether, among all the ardent evolutionists who have had their say H Z ■*
on the moral and the educational question, any one has carried forward the 5 s!o
new doctrine so boldly to its extreme logical consequence." — Professor Q«g
Sully m Mind. •<

XVL THE MAN OF GENIUS. By Prof. Lombroso. Illus- ^

trated. >■

"By far the most comprehensive and fascinating collection of facts and Q

generalisations concerning genius which has yet been brought together." — "

fournal of Menial Science. ^

New York : Charles Scribner's Sons. ^

XVII. THE HISTORY OF THE EUROPEAN FAUNA.
By R. F. SCHARFF, B.Sc, Ph.D., F.Z.S. Illustrated.

XVIII. PROPERTY : ITS ORIGIN AND DEVELOPMENT.

By Ch. Letourneau, General Secretary to the Anthro-
pological Society, Paris, and Professor in the School of Anthro-
pology, Paris.

" M. Letourneau has read a great deal, and he seems to us to have
selected and interpreted his facts with considerable judgment and learning."
— Westminster Review.

XIX. VOLCANOES, PAST AND PRESENT. By Prof.
Edward Hull, LL.D., F.R.S.

" A very readable account of the phenomena of volcanoes and earth-
quakes. " — Nature.

XX. PUBLIC HEALTH. By Dr. J. F. J. Sykes. With

numerous Illustrations.
"Not by any means a mere compilation or a dry record of details and
statistics, but it takes up essential points in evolution, environment, prophy-
laxis, and sanitation bearing upon the preservation of public health." —
Lancet.

XXL MODERN METEOROLOGY. An Account of the
Growth and Present Condition of some Branches
OF Meteorological Science. By Frank Waldo, Ph.D.,
Member of the German and Austrian Meteorological Societies,
etc.; late Junior Professor, Signal Service, U.S.A. With 112
Illustrations.
"The present volume is the best on the subject for general use that we
have seen." — Daily Telegraph (London).

XXIL THE GERM-PLASM : A THEORY OF HEREDITY.

By August Weismann, Professor in the University of
Freiburg-in-Breisgau. With 24 Illustrations. $2.50.
"There has been no work published since Darwin's own books which
has so thoroughly handled the matter treated by him, or has done so much
to place in order and clearness the immense complexity of the factors of
heredity, or, lastly, has brought to light so many new facts and considerations
bearing on the subject." — British Aledical Journal.

XXIII. INDUSTRIES OF ANIMALS. By E. F. Houssay.
With numerous Illustrations.
" His accuracy is undoubted, yet his facts out-maryel all romance. These
facts are here made use of as materials wherewith to form the mighty fabric
of evolution." — Manchester Guardian.

New York : Charles Scribner's Sons.

XXIV. MAN AND WOMAN. By Havelock Ellis. Illus-
trated. Fourth and Revised Edition'.

" Mr. Havelock Ellis belongs, in some measure, to the continental school
of anthropologists ; but while equally methodical in the collection of facts,
he is far more cautious in the invention of theories, and he has the further
distinction of being not only able to think, but able to write. His book is
a sane and impartial consideration, from a psychological and anthropological
point of view, of a subject which is certainly of primary interest." —
Athenaum.

XXV. THE EVOLUTION OF MODERN CAPITALISM.

By John A. Hobson, M.A. (New and Revised Edition.)

" Every page affords evidence of wide and minute study, a weighing of
facts as conscientious as it is acute, a keen sense of the importance of certain
points as to which economists of all schools have hitherto been confused and
careless, and an impartiality generally so great as to give no indication of his
[Mr. Hobson's] personal sympathies." — Pall Mall Gazette.

XXVI. APPARITIONS AND THOUGHT - TRANSFER-
ENCE. By Frank Podmore, M.A.

"A very sober and interesting little book. . . . That thought-transfer-
ence is a real thing, though not perhaps a very common thing, he certainly
shows. " — Spectator.

XXVII. AN INTRODUCTION TO COMPARATIVE
PSYCHOLOGY. By Professor C. Lloyd Morgan. With
Diagrams.

" A strong and complete exposition of Psychology, as it takes shape in a
mind previously informed with biological science. . . . Well written, ex-
tremely entertaining, and intrinsically valuable." — Saturday Review.

XXVIII. THE ORIGINS OF INVENTION : A Study of
Industry among Primitive Peoples. By Otis T. Mason,
Curator of the Department of Ethnology in the United States
National Museum.

"A valuable history of the development of the inventive faculty." —
Nature.

XXIX. THE GROWTH OF THE BRAIN: A Study of
the Nervous System in relation to Education. By
Henry Herbert Donaldson, Professor of Neurology in the
University of Chicago.

" We can say with confidence that Professor Donaldson has executed his
work with much care, judgment, and discrimination." — 'The Lancet.

XXX. EVOLUTION IN ART: As Illustrated by the
Life-Histories of Designs. By Professor Alfred C.
H ADDON. With 130 Illustrations.

" It is impossible to speak too highly of this most unassuming and
invaluable hoo\i." —Journal of Anthropological Institute.

New York : Charles Scribner's Sons.

XXXL THE PSYCHOLOGY OF THE EMOTIONS. By
Th. Ribot, Professor at the College of France, Editor of the
Revue Philosophique.
"Professor Ribot's treatment is careful, modern, and adequate." —
'Academy.

XXXn. HALLUCINATIONS AND ILLUSIONS: A Study
OF THE Fallacies of Perception. By Edmund Parish.
"This remarkable little volume." — Daily News.

XXXIII. THE NEW PSYCHOLOGY. By E. W. Scripture,
Ph.D. (Leipzig). With 124 Illustrations.

XXXIV. SLEEP : Its Physiology, Pathology, Hygiene, and
Psychology. By Marie de Manaceine (St. Petersburg).
Illustrated.

XXXV. THE NATURAL HISTORY OF DIGESTION.

By A. Lockhart Gillespie, M.D., F.R.C.P. Ed., F.R.S.
Ed. With a large number of Illustrations and Diagrams.
"Dr. Gillespie's work is one that has been greatly needed. No com-
prehensive collation of this kind exists in recent English Literature." —
American Journal of the Medical Sciences.

XXXVI. DEGENERACY: Its Causes, Signs, and Results.
By Professor EuGENE S. Talbot, M.D., Chicago. With
Illustrations.

"The author is bold, original, and suggestive, and his work is a con-
tribution of real and indeed great value, more so on the whole than anything
that has yet appeared in this country." — American Journal of Psychology.

XXXVII. THE RACES OF MAN: A Sketch of Ethno-
graphy AND Anthropology. By J. Deniker. With 178
Illustrations.

"Dr. Deniker has achieved a success which is well-nigh phenomenal." —
British Medical journal.

XXXVIII. THE PSYCHOLOGY OF RELIGION. An
Empirical Study of the Growth of Religious Con-
sciousness. By Edwin Diller Starbuck Ph.D., Assistant
Professor of Education, Leland Stanford Junior University,

" No one interested in the study of religious life and experience can
afford to neglect this volume. " — Morning Herald,

XXXIX. THE CHILD : A Study in the Evolution of Man.
By Dr. Alexander Francis Chamberlain, M.A., Ph.D.,
Lecturer on Anthropology in Clark University, Worcester
(Mass.). With Illustrations.

"The work contains much curious information, and should be studied by
those who have to do with children." — Sheffield Daily Telegraph.

New York : Charles Scribner's Sons.

XL. THE MEDITERRANEAN RACE. By Professor Sergi.
With over loo Illustrations.
" M. Sergi has given us a lucid and complete exposition of his views on a
subject of supreme interest." — Irish Times.

XLI. THE STUDY OF RELIGION. By Morris Jastrow, '
Jun., Ph.D., Professor in the University of Pennsylvania.
"This work presents a careful survey of the subject, and forms an
admirable introduction to any particular branch of it." — Methqdist Times.

XLII. HISTORY OF GEOLOGY AND PALEONTOLOGY
TO THE END OF THE NINETEENTH CENTURY.
By Karl von Zittel.
'* It is a very masterly treatise, written with a wide grasp of recent
discoveries. " — Publishers' Circular.

XLIII. THE MAKING OF CITIZENS : A Study in Com-
parative Education. By R. E. Hughes, M.A. (Oxon.),
B.Sc. (Lond.).
"Mr. Hughes gives a lucid account of the exact position of Education in
England, Germany, France, and the United States. The statistics
present a clear and attractive picture of the manner in which one of the
greatest questions now at issue is being solved both at home and abroad."
— Standard.

XLIV. MORALS: A Treatise on the Psycho-Sociological
Bases of Ethics. By Professor G. L. Duprat. Trans-
lated by W. J. Greenstreet, M.A., F.R.A.S.
"The present work is representative of the modern departure in the
treatment of the theory of morals. The author brings a wide knowledge
to bear on his subject." — Education.

XLV. A STUDY OF RECENT EARTHQUAKES. By
Charles Davison, D.Sc, F.G.S. With Illustrations.
" Dr. Davison has done his work well." — Westminster Gazette.

XLVI. MODERN ORGANIC CHEMISTRY. By Dr. C. A.
Keane, D.Sc, Ph.D., F.I.C. With Diagrams.
" This volume provides an instructive and suggestive survey of the great
range of knowledge covered by modern organic chemistry." — Scotsman.

TO-DAY'S ADDITIONS:—

THE CRIMINAL. By Havelock Ellis. Fourth Edition,
Revised and Enlarged.

XLVII. THE JEWS : A Study of Race and Environment.
By Dr. Maurice- Fishberg.
"It shows abounding evidence in its pages that it is intended to show,
immense industry, consummate pains, vast literary and statistical resources.
It contains, to be sure, much information of great value, and it sets forth
many facts absorbing in their interest for any who desire to study the
Jewish people. "—yeii'zV;^ Chronicle.

New York: Charles Scribner's Sons.

IBSEN'S DRAMAS.

Edited by WILLIAM ARCHER.

O THREE PLAYS TO THE VOLUME.

5 i2mo, CLOTH, PRICE $1.25 PER VOLUME.

" We seem at last to be shown men- and women as they are ; and at first it
S is more than we can endure. . . . All Ibsen^s characters speak and act as if

M they were hypnotised, and under their creator's imperious demand to reveal

K themselves. There never was such a mirror held up to nature before : it is

too terrible, . . . Yet we must return to Ibsen, with his remorseless surgery,
^ his remorseless electric -light, until we, too, have grown strong and learned to

^ face the naked — if necessary, the flayed and bleeding— reality.^'' — Speaker

W (London).

fa M Vol. I. "A DOLL'S HOUSE," "THE LEAGUE OF

^ S YOUTH," and "THE PILLARS OF SOCIETY." With

2; !D Portrait of the Author, and Biographical Introduction by

O ^ WilliamArcher.

S ^ Vol. II. " GHOSTS," " AN ENEMY OF THE PEOPLE,"
§ M and "THE WILD DUCK." With an Introductory Note.

\1 ^ J^OL. in. "LADY INGER OF OSTRAT," "THE VIKINGS
W Q AT HELGELAND," "THE PRETENDERS." With an

^ ^ Introductory Note.

g ^ Vol. IV. " EMPEROR AND GALILEAN." With an
U ^ Introductory Note by William Archer.

9 pJ Vol. V. "ROSMERSHOLM," "THE LADY FROM THE
< CO SEA," "HEDDA GABLER." Translated by William

. Archer. With an Introductory Note.

S V^OL. VL "PEER GYNT: A DRAMATIC POEM."

M Authorised Translation by William and Charles Archer.

S The sequence of the plays in each volume is chronological ; the complete

i set of volumes comprising the dramas thus presents them in chronological

order.
CO

'"' " The art of prose translation does not perhaps enjoy a very high literary

C/3 status in England, but we have no hesitation in numbering the present

hH version of Ibsen, so far as it has gone (Vols. I. and II.), among the very

f-i best achievements, in that kind, of our generation." — Academy.

f^ «« Wg have seldom, if ever, met with a translation so absolutely

idiomatic." — Glasgow Herald.

New York : Charles Scribner's Sons.

V ■■"■". i>''. :' V

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