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MAR 23

— ., .-c

THE FITNESS
OF THE ENVIRONMENT

THE MACMILLAN COMPANY

NEW YORK • BOSTON • CHICAGO
DALLAS • SAN FRANCISCO

MACMILLAN & CO., Limited

LONDON • BOMBAY • CALCUTTA
MELBOURNE

THE MACMILLAN CO. OF CANADA, Ltd.

TORONTO

THE FITNESS
OF THE ENVIRONMENT

AN INQUIRY

INTO THE BIOLOGICAL SIGNIFICANCE OF

THE PROPERTIES OF MATTER

BY

LAWRENCE J. HENDERSON

ASSISTANT PROFESSOR OF BIOLOGICAL CHEMISTRY
IN HARVARD UNIVERSITY

IN PAET DELIVERED AS LECTURES IN THE
LOWELL INSTITUTE, FEBRUARY, 1913

THE MACMILLAN COMPANY
1924

AU rights reserved

PRINTED IN THE UNITED STATES OF AMERICA

,

Copyright, 1913,
Bt THE MACMILLAN COMPANY.

Set up and electrotyped. Published February, 1913.

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Norwood, Mass., U.S.A.

LIBRARY

N. C. State College

PREFACE

Darwinian fitness is compounded of a
mutual relationship between the organism
and the environment. Of this, fitness of en-
vironment is quite as essential a component as
the fitness which arises in the process o* or-
ganic evolution ; and in fundamental charac-
teristics the actual environment is the fittest
possible abode of life. Such is the thesis
which the present volume seeks to establish,
This is not a novel hypothesis. In rudimen-
tary form it has already a long history behim
it, and it was a familiar doctrine in the early
nineteenth century. It presents itself anew
as a result of the recent growth of the science
of physical chemistry.

About fifteen years ago I first became inter-
ested in the connection between physical and
chemical properties of simple substances and
the organic functions which they serve. At
that time the applications of the new physical
chemistry to physiology were only just begin-
ning, and the older speculations of natural
theology upon such subjects had long since

v

11481

y[ PREFACE

passed into oblivion. It was a time of very
little interest in such matters, for many lines
of development of natural science during the
preceding quarter century had conspired to
divert attention to other problems. The im-
mediate occasion of my interest was, I well
remember, the chance reading of Maly's im-
portant but almost forgotten papers upon
the diffusion and dialysis of phosphates, re-
counting phenomena which, in the light of the
modern theory of ionization, appeared simple
enough, though to their discoverer they had
heel in some respects inexplicable. A series
of researches have grown out of this interest,
ard since that time, whenever freedom has
permitted, I have been occupied with various
aspects of the problem of the neutrality or
/aint alkalinity of the organism. For it soon
appeared that the key to the peculiar condi-
tions of equilibrium between acids and bases
in blood and protoplasm is to be found in such
characteristics of phosphate solutions as Maly
had observed, and in like behavior of similar
solutions containing carbonic acid. When at
length it became possible quantitatively to
describe the chemical equilibra in such sys-
tems, it was at once clear that, of all known
substances, phosphoric acid and carbonic acid
possess the greatest power of automatic regu-

PREFACE vii

lation of neutrality (the concentration of ion-
ized hydrogen and hydroxyl at the neutral
point).

One does not like to accept a fact of such
far-reaching importance as mere chance, and
yet no other explanation was at hand. For,
after the briefest consideration, it was obvious
that here, at least, natural selection could not
be involved. But it was also certain that tin's
is no unique instance of a property of a simple
substance automatically serving a very useful
purpose in the processes of life. Like every
one who has received a chemical training, I
was vaguely conscious of numerous other simi-
lar cases ; like every one who has any acquaint-
ance with the general properties of matter, I
knew that the remarkable thermal properties
of water are of great importance to living or-
ganisms. However, in spite of the fact inat
I had been brought face to face with a definite
problem whose solution now appears to he
perfectly patent, so great is the natural inertia
of the mind, and so firmly established was thf
belief that natural selection is, on the whole,
quite adequate to account for biological fit-
ness, that for a number of years I made no
further progress.

Then, finally, after a long period of uncer-
tainty, came the realization of the reciprocal

viii PREFACE

character of Darwinian fitness, and at once
the whole difficulty was resolved. On all
sides instances of environmental fitness were
manifest, and casual search brought many
other cases to light. The forgotten literature
of natural theology is crammed with illustra-
tions, and the recent biological developments
of physical chemistry have provided still
others. It is, indeed, a very curious episode
in the history of thought that these well-
known facts should have been so long forgot-
ten or misconstrued. But, though forgotten,
they have, so to speak, lain dormant in the
minds of physical scientists, and I have found
both chemists and physicists ready to accept
them without hesitation. In the following
pages an attempt has been made to collect
and to interpret such facts, in so far as they
arise among the compounds of carbon, hydro-
gen, and oxygen, especially in the cases of
witer and carbonic acid. This restriction has
been adopted in order to facilitate the logical
discussion, and it should be borne in mind
that other phenomena, dependent upon the
properties of other substances, such as the
above-mentioned characteristics of phosphate
solutions, belong in the same category.

The argument which has been thus devel-
oped is comparatively rigid and closely woven.

PREFACE ;x

That is, perhaps, in some respects unfortuna te,
because the impression which must be pro-
duced is unlike that of the facts themselves,

and the argument is certainly very different
from the mental process through which I have
myself passed in reaching the conclusion. Bui
it would be very difficult indeed in any other
manner to set forth all the necessary consid-
erations, so that they should be intelligible to
any one but the physico-chemical biologist,
and on the whole there seems to be no choice
but to follow a logical rather than a descrip-
tive method. The reader will find, however,
that in the main Chapters III, IV, V, and
VI are concerned with evidence alone. This
taken together, as a whole, is the only true
ground for a conclusion, and it is upon the
general character of the evidence rather than
upon an argument which only serves as a
means to the end that I should wish to rest
my case. To many, on the other hand, as to
any biologist who may not care to examine
the difficult facts of physics and chemistry.
Chapters I, II, VII, and VIII will be sufficient
to explain both the purpose of the book and
the outcome of the investigation.

There has been a constant effort to restrict all
discussions to the utmost, because at the pres-
ent time encyclopaedic handbooks cover Jul; all

x PREFACE

departments of science have so multiplied that
hardly any facts or theories which come within
the scope of this work are inaccessible to the
general reader. On the other hand, it has
been deemed necessary to explain every sub-
ject as it has arisen, for many of the readers
of this volume will perhaps be unfamiliar even
with the rudiments of all the departments of
science which have necessarily been touched
upon.

Much of the content of the following pages
has already been set forth in lectures. The
general conclusion was presented last February
to the members of the Harvard Seminary of
Logic ; later in the academic year I delivered
the substance of the book as part of a college
course to my students of biological chemistry
in Harvard College.

I am indebted to many of my colleagues in
Harvard for valuable assistance, criticism,
and expressions of opinion. Without such
assurances that I have not fallen into gross
blunders, and that the conclusions appear rea-
sonable to experienced men of science, I should
not have dared to undertake a task which
overtaxes my knowledge, or positively to as-
sert a proposition which is in conflict with
much of the scientific thought of the last half
century. Especial thanks are due to Professor

PREFACE xj

Josiah Royce. His learning and generosity
have in the past aided me to reach an under-
standing of the philosophical problems of sci-
ence, and in the preparation of this book they

have repeatedly guided me aright.

Seal Harbor, Maine,
August, 1912.

CONTENTS
CHAPTER I

page

FITNESS 1

I. Purpose and Order 1

II. Fitness 4

III. The Environment 8

A. Matter 8

B. Energy 15

C. Space and Time 19

IV. The Organism 21

A. Metabolism i±

B. Organic Chemistry 28

C. The Characteristics of Life .... 30

V. The Problem 36

CHAPTER II

THE ENVIRONMENT 38

I. Astronomy 38

II. Possible Environments M

III. Geophysics M

IV. The Atmosphere

-.

..i

V. General Cosmograptiical Conclusions . . <*.o
VI. The Primary Constituents of the Environ-
ment (>1

VII. The Ultimate Problem

VIII. The Method of Solution \ . C7

xiii

xiv CONTENTS

CHAPTER III

PASS

WATER 72

I. Thermal Properties 80

A. Specific Heat 80

B. Latent Heat 92

C. Thermal Conductivity 106

D. Expansion before Freezing . . . .106
II. The Action of Water upon Other Substances 110

A. Water as a Solvent Ill

B. Ionization 118

C. Surface Tension 126

CHAPTER IV

CARBONIC ACID 133

I. Solubility 136

II. Acidity 140

CHAPTER V

THE OCEAN 164

I. The Regulation of Physico-chemical Conditions 164

II. The Circulation of Water 180

III. The Ocean as Environment .... 183

CHAPTER VI

THE CHEMISTRY OF THE THREE ELEMENTS . 191

I. Organic Chemistry 191

A. Valence 196

B. Hydrocarbons 197

CONTENTS , v

lA. K

C. Compounds of Carbon, Hydrogen, and Oxygen MM

D. Other Organic Compounds . t |qq

£. The Characteristics of Organic Substances . MM

F. The Sugars ^

G. Hydrolysis ^

II. Inorganic Chemistry .... Mr

III. Thermochemistry .... W;j

CHAPTER VII

THE ARGUMENT 249

I. Analysis of the Evidence . . . $50

II. The Exhaustiveness of the Treatment . |fl

III. Summary ag»

CHAPTER VIII

LIFE AND THE COSMOS 274

I. The Significance of Fitness . 274

II. Vitalism ^Sl»

A. The Vitalism of Bergson 293

B. Vitalism and Teleology 298

HI. Cosmic Evolution 30 1

A. The Periodic System 303

B. Teleology 305

CHAPTER I
FITNESS

PURPOSE AND ORDER

IDEAS of purpose and order are among
the first concepts regarding their en-
vironment which appear, as vague antici-
pations of philosophy and science, in the
minds of men. In truth, when the manifold
phenomena and experiences of daily life
stored in the memory are critically scruti-
nized, purpose and order seem naturally to
suggest themselves as explanations of the
universe. Day and night, the changing but
recurring seasons, the fertilizing sunshine
and rain, the flight of birds, the powers of
the human hand, and all the beau tits and
mysteries of nature cannot fail of such in-
terpretation by the simple and untrained
mind. Alike anthropology and the history
of primitive civilizations bear witness to this
natural tendency of thought. Such ideas pre-

B 1

2 THE FITNESS OF THE ENVIRONMENT

cede exact knowledge and civilization, and
arise spontaneously among savage peoples.
They are the solvent of the chaos, as which
the outer world first presents itself to our
eyes and hands, and they are the fabric of
all theologies.

As civilization has progressed, these early
hypotheses have received endless criticism,
and their definition has been continually
sharpened. Meantime natural science has
sought and provided ever more accurate
accounts of the phenomena which first sug-
gested them to man, and of countless other
forms and transformations of matter and
energy, and the discovery of laws of nature
has steadily changed once quite mysterious
order and purpose into the plainest of neces-
sary results.

Upon the advent of modern science order
speedily began to receive its true account
when, after only a half century of progress,
dynamics through Newton provided a formu-
lation of the laws which govern the most
striking of all the orderly phenomena of
nature.1 Since Newton's day the explana-

1 '* Die Newton'schen Principien sind genligend, um ohne
Hinzuziehung eines neuen Princips jeden praktisch vorkom-
menden mechanischen Fall, ob derselbe nun der Statik oder
der Dynamik angehort, zu durchschauen. Wenn sich hierbei
Schwierigkeiten ergeben, so sind dieselben immer nur mathe-

FITNESS 3

tion of natural order as the automatic result
of natural law has not ceased, and at length
has become so nearly complete that the ap-
pearance of order under any circumstances is
now taken as proof of the existence of a law.

The fate of the hypothesis of purpose in
nature has been less simple, because the dis-
covery of law, or even of the possibility of
law, underlying adaptation and fitness was
more difficult. Until the middle of the nine-
teenth century the countless adaptations of
organisms to the environment and the mani-
fest fitness of nature for the activities of
living things seemed to many biologists only
explicable as the result of some directing
force.1 Even skeptics were nearly or quite

mathischer (formeller) und keineswegs mehr principieller
Natur." — Mach, "Die Mechanik in Ihrer Entwickelung
Historisch-Kritisch Dargestellt." Leipzig, 1897, 3d ed., p. 257.

" Dann hat er auch die Aufstellung der heute angenom-
men Principien der Mechanik zu einem Abschluss gebracht."
— Mach, ibid. p. 181.

1 See for example that remarkable series of works, the
Bridgewater Treatises "On the Power, Wisdom, and Goodness
of God, as manifested in the Creation ; illustrating such work
by all reasonable arguments, as for instance the variety and
formation of God's creatures in the animal, vegetable, and
mineral kingdoms ; the effect of digestion, and thereby of
conversion ; the construction of the hand of man, and an
infinite variety of other arguments ; as also by discoveries
ancient and modern, in arts, sciences, and the whole extent
of literature." — Whewell, "Astronomy and General Phys-

4 THE FITNESS OF THE ENVIRONMENT

unable, however strong their desire, to ac-
count for the facts with a plausible theory.
The dogma of final causes had led a thou-
sand times to the truth by teaching the
investigator that the true description of an
organ or physiological process was to be found
in its utility to the organism as a whole.
Such considerations were far too numerous
and too patent for science to shirk some
explanation, and the only weighty explana-
tion at hand seemed the teleological one.

n

FITNESS

With a suddenness which to many seemed
catastrophic Darwin's hypothesis of natural
selection changed the whole aspect of the
problem. Law appeared as the basis of
purpose just as it had appeared as the basis of
order, and adaptations became, in the judg-
ment of most men, the necessary results of
an automatic process. To-day, after a half
century, there is no longer room for doubt
that the fitness of organic beings for their life
in the world has been won in whole or in part

ics Considered with Reference to Natural Theology." Lon-
don, 1834, 4th ed., p. ix.

To this series such men as Whewell and Sir Charles Bell
contributed.

FITNESS 5

by an almost infinite series of adaptations of
life to its environment, whereby, through a
corresponding series of transformations, pres-
ent complexity has grown out of former sim-
plicity.1

The great and fruitful ideas which Darwin
brought to the attention of the whole world
have long since been incorporated into hu-
man thought. Not the least important
among them is the new scientific concept of
fitness, as it emerges from the discussion of
natural selection. Before Darwin, this concept
possessed all the vagueness of an idea which,
though in part founded on observation, was
not to be explained with the help of existing
scientific theories. But although Darwin's
fitness involves that which fits and that which
is fitted, or more correctly a reciprocal rela-
tionship, it has been the habit of biologists
since Darwin to consider only the adaptations
of the living organism to the environment.2

1 The ideas which are associated with the names of de
Vries, as well as the very different hypotheses of Driesch,
Bergson, and others are, of course, concerned with the manner,
not with the fact of adaptation and organic evolution.

2 Far different was the earlier point of view. An examina-
tion of Whewell's Bridgewatcr Treatise at once reveals im-
portant, if often fallacious, discussions of environmental fit-
ness; e.g. "It has been shown in the preceding chapters that
a great number of quantities and laws appear to have been
selected in the construction of the universe ; and that by the

6 THE FITNESS OF THE ENVIRONMENT

For them, in fact, the environment, in its
past, present, and future, has been an inde-
pendent variable, and it has not entered into
any of the modern speculations to consider
if by chance the material universe also may
be subjected to laws which are in the largest
sense important in organic evolution. Yet
fitness there must be, in environment as well
as in the organism. How, for example, could
man adapt his civilization to water power if
no water power existed within his reach ?

adjustment to each other of the magnitudes and laws thus
selected, the constitution of the world is what we find it, and
is fitted for the support of vegetables and animals in a manner
in which it could not have been, if the properties and quan-
tities of the elements had been different from what they are.
We shall here recapitulate the principal of the laws and
magnitudes to which this conclusion has been shown to

apply.

1. The Length of the Year, which depends on the force of
the attraction of the sun, and its distance from the earth.

2. The Length of the Day.

3. The Mass of the Earth, which depends on its magni-
tude and density.

4. The Magnitude of the Ocean.

5. The Magnitude of the Atmosphere.

6. The Law and Rate of the Conducting Power of the
Earth.

7. The Law and Rate of the Radiating Power of the

Earth.

8. The Law and Rate of the Expansion of Water by Heat.

9. The Law and Rate of the Expansion of Water by Cold,
below 40 degrees.

FITNESS 7

At first sight it may well seem that inquiry
into such a problem must end unsuccessfully
in vague and unprofitable guesses. Indeed
the past has brought forth no lack of such vain
attempts, usually guided by a devotion to
the doctrine of design in the service of the-
ology. Yet other sciences have grown since
1859, and physical and chemical data in
abundance are now at hand to aid in a recon-
sideration of the environment's fitness, if

10. The Law and Quantity of the Expansion of Water by
Freezing.

11. The Quantity of Latent Heat absorbed in Thawing.

12. The Quantity of Latent Heat absorbed in Evapora-
tion.

13. The Law and Rate of Evaporation with regard to
Heat.

14. The Law and Rate of the Expansion of Air by Heat.

15. The Quantity of Heat absorbed in the Expansion of
Air by Heat.

16. The Law and Rate of the Passage of Aqueous Vapor
through Air.

17. The Laws of Electricity; its relations to Air and
Moisture.

18. The Fluidity, Density, and Elasticity of the Air, by
means of which its vibrations produce Sound.

19. The Fluidity, Density, and Elasticity of the Ether,
by means of which its vibrations produce Light." — Whe-
well, "Astronomy and General Physics Considered with
Reference to Natural Theology." London, 1834, 4th ed.,
pp. 141-143.

It is hard to understand how such ideas could have fallen
into oblivion.

8 THE FITNESS OF THE ENVIRONMENT

such exist. Clearly it is well to seek among
these data for a more precise formulation of
the problem, which may then perchance lead
to some more ambitious quest, or at least to
new understanding of the old failure.

Ill

THE ENVIRONMENT

The world of our senses is a world of matter
and energy, space and time. After centuries
of philosophical and scientific study, these,
the very logical elements of science, are no
doubt still without a final description. None
the less is there sound foundation for the
belief that our preliminary accounts of all
four possess completeness in some respects
and for certain purposes. Nor are we to-day
less confident of the finality of some of our
ideas regarding the nature of life and the vital
processes, as they exist in this world. But
both of these conclusions call for further
consideration.

A

MATTER

Many facts contribute to the belief, uni-
versal among chemists, that the known ele-
ments constitute by far the greatest part of

FITNESS 9

a system of materials out of which the uni-
verse is formed, within which all chemical
changes (except certain phenomena of radium
and a few other anomalies, including perhaps
unknown changes in the interiors of the
celestial bodies) take place.

It is certain that nearly all the chemical
transformations upon the earth consist of
rearrangements of the atoms of the known
elements. A century and a half of scientific
chemistry guarantee that conclusion with a
security rarely attained in descriptive science.
And the testimony of the spectroscope is
equally conclusive that the visible stars,
like the sun itself, are made up almost or
quite exclusively of the same chemical ele-
ments. Such facts, so familiar that thev re-
quire no comment or explanation, might
sufficiently justify the acceptance of the chem-
ist's known elements as the only important
matter in the universe. But even more
weighty evidence is at hand ; I mean the
so-called periodic classification of the ele-
ments.

It has long been evident that simple rela-
tionships exist in some cases between the
atomic weights of similar elements. For ex-
ample, the atomic weights of bromine, stron-
tium, and selenium are approximately equal

10 THE FITNESS OF THE ENVIRONMENT

to the means of the atomic weights of chlorine
and iodine, of calcium and barium, and of
sulphur and tellurium respectively. More
general relationships between the atomic
weights and properties of the elements were
first pointed out by Newlands in 1864 and
were extended by Mendeleeff and Lothar
Meyer a little later. Out of these studies
has arisen the law that the properties of the
elements are periodic functions of their atomic
weights.

The essential characteristics of this law are
best illustrated by a consideration of the
relative volumes occupied by atoms of the
various elementary substances, the so-called
atomic volumes, which may be expressed by
dividing atomic weights by specific gravities.
The facts are graphically represented upon
the accompanying diagram, where atomic
weights are plotted horizontally, atomic vol-
umes vertically.

Beginning with lithium the volumes fall
to boron and carbon, then rise irregularly to
sodium. A second fall leads to aluminium,
a second rise to potassium, and then the rises
and falls of the curve are repeated until,
among the elements of higher atomic weight,
gaps break the continuity of the relationship.
On the whole curve similar elements occupy

FITNESS

11

-8

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12 THE FITNESS OF THE ENVIRONMENT

similar positions. Thus the alkali metals,
lithium, sodium, potassium, rubidium, and
caesium, occupy the crests of the waves; the
halogens, fluorine, chlorine, bromine, and
iodine, fall about midway between crests
and troughs, and a little further study dis-
closes a host of other corresponding relation-
ships.

Similar periodic variations may be shown
to occur in other physical properties of the
elements ; — the melting points, the boiling
points, the magnetic characteristics, etc.
Even more striking are the periodic varia-
tions in chemical properties, including the
general characteristics which first led to the
idea of rational classification, and more spe-
cific qualities like the combining powers for
hydrogen, oxygen, and other elements.

The clearest proof of the value of the
periodic classification has been the predic-
tion of "new' elements, and accurate fore-
knowledge of their properties. Thus when
Mendeleeff first described the system, the
element germanium, discovered by Winkler
in 1886, was unknown; but from the proper-
ties of the elements surrounding a gap in the
system the Russian chemist was able to
predict its properties with almost incredible
exactness, as the following table shows.

FITNESS

13

Atomic weight . . .
Specific gravity . . .
Atomic volume . . .
Formula of oxide . .
Specific gravity of oxide
Formula of chloride
Boiling point of chloride
Specific gravity of chloride
Formula of fluoride . .
Formula of ethyl compound
Specific gravity of ethyl compound

Prediction

72.0

5.5
13
Ge02

4.7
GeCU
Less than 100°

1.9
GeFl4
Ge(C2H5)4

0.96

Observation

72.3
5.469
13.2
Ge02

4.703
GeCU

86°
1.9
GeFU

Ge(C2Hfi)4
Lower than water

Finally it is to be especially noted that,
upon arranging the known elements in a
table rationally constructed upon the basis
of the above recorded facts, comparatively
few spaces within the range of known atomic
weights remain to be filled. The conclusion
is obvious that very few elements now un-
known are possible unless they possess very
high atomic weights. But the apparent
transmutation of radium into helium is a
pretty clear indication that elements of very
high atomic weight may be unstable. If
they have existed in number and large quan-
tity, they probably have long since ceased
so to exist, except perhaps in the interior
of celestial bodies, and they are not likely
elsewhere to complicate natural phenomena
by their unknown properties.

14 THE FITNESS OF THE ENVIRONMENT

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FITNESS 15

The behavior of radium and the classifica-
tion itself suggest one further idea: the hy-
pothesis that the elements are genetically
related, that they have been evolved by some
unknown process according to unknown laws.
Certain it is that the properties of matter are
no chance phenomena, and that transmuta-
tion has ceased to be merely a philosopher's
dream.

All of these familiar facts of chemical science
fully justify us in dealing with matter as a
known factor in the study of life conditions
in the universe. For, whatever mav be the
fate of present theories, our present practical
knowledge of the behavior of matter cannot
fail us in the future.

B

ENERGY

Contemporary with the work of Darwin
and of Mendeleeff were the feats of Maver,
Joule, Helmholtz, Kelvin, and Clausius,
whereby ideas of energy assumed their mod-
ern aspect. In the revolution wrought by
these men imponderables and fluids vanished
from this domain, and energy became that
which, not being matter, is conserved. The
new principles of the 'fifties have held their
own until to-day. Meantime they have

16 THE FITNESS OF THE ENVIRONMENT

made of thermodynamics (the department of
science which is especially concerned with
the laws of energy transformation) a sub-
ject which few who cultivate the physical
sciences may disregard. Countless develop-
ments and achievements of thermodynamics
give very real ground for the belief that we
may speculate about the transformations of
energy in the universe with the same assur-
ance that we have in discussing chemical
changes.

Our reasons for confidence in the truth of
current general notions of energy, and in
their adequacy to account for any phenomena
so far as energy is concerned, wherever life
exists in the universe, are manifold, and not
unlike those which have been reviewed in dis-
cussing the elements.

Centuries of search have revealed, in addi-
tion to that most obvious form which is
studied in dynamics, a very small number of
varieties or manifestations of energy, such as
heat, electricity, magnetism, optical energy,
and chemical energy. Such manifestations
of energy are by no means confined to the
earth or to the solar system. Indeed Newton
first worked out the general laws of dynamics
and erected them into a complete science
with the aid, not of terrestrial, but of astro-

FITNESS 17

nomical phenomena.1 And recent most re-
markable studies of the stars have enabled
astronomers to account for obscure events
in far distant parts of the universe by the
application of the principles of dynamics.
Similarly light, heat, and chemical energy, as
we know them, are unquestionably universal.
No doubt the manifestations of energy
within the sun and stars, like the accompany-
ing material phenomena there, can to-day
only be surmised. For aught we know,
these places may, as has been guessed, be the
birthplace of elements and the seat of mani-
festations of energy quite different from

1 "What the Occasion of Sir Isaac Newton's leaving the
Cartesian Philosophy, and of discovering his amazing Theory
of Gravity was, I have heard him long ago, soon after my first
Acquaintance with him, which was 1694, thus relate, and of
which Dr. Pemberton gives the like Account, and somewhat
more fully, in the Preface to his Explication of his Philos-
ophy : It was this. An Inclination came into Sir Isaacs
Mind to try, whether the same Power did not keep the Moon
in her Orbit, notwithstanding her projectile Velocity, which
he knew always tended to go along a strait Line the Tangent
of that Orbit, which makes Stones and all heavy Bodies with
us fall downward, and which we call Gravity? Taking this
Postulatum, which had been thought of before, that such
Power might decrease, in a duplicate Proportion of the Dis-
tances from the Earth's Center." — "Memoirs of the Life
of Mr. William Whiston by Himself." London, 1749, Vol. I,
pp. 35-38. Quoted by Ball. "An Essay on Newton's Prin-
cipia." London, 1893, p. 8.

G

18 THE FITNESS OF THE ENVIRONMENT

what we have ever observed. But, however
interesting and important such processes may
be, it is not to be supposed that they are of
direct moment in physiological processes.
These conditions are far beyond the limits
of our present investigation. Accordingly,
everything that observation has taught con-
firms the belief that energy, like matter, is
in general well known to us. Its manifesta-
tions are few, and they are universal. But
just as the generalizations of science yield
further assurance regarding matter, so they
do not fail to confirm our conclusions in the
study of energy. The law of the conserva-
tion of energy and the law of the degradation
of energy, otherwise known as the first and
second laws of thermodynamics, clearly in-
dicate that the manifestations of energy are
not accidental nor independent of one an-
other. They are orderly, and they obey laws.
Energy is one and indestructible.

Such are the apparently irrefragable con-
clusions of the brief half century of creative
development, from the time when Young
first used the word "energy" and Bolton and
Watt first employed the idea of measuring
energy in horse power, through the period of
Carnot's brilliant intuition regarding the re-
lation between heat and work, to the epoch

FITNESS 1 0

of the foundation of thermodynamics.1 To-
day we know that just so much heat, neither
more nor less, may be obtained by the com-
plete conversion of a unit of electrical energy
or by a given chemical process. We know,
moreover, that not every conceivable change
from one form of energy to another is possible.
On the whole, energy can flow in but one
direction; perpetual motion is impossible;
and useful energy is steadily becoming de-
graded, dissipated, and useless.

Such laws are fully worthy of a place be-
side the periodic law, and they justify equal
confidence in the adequacy of our current
descriptions of matter and of energy for the
purposes of biology.

C

SPACE AND TIME

Since Kant revolutionized modern phi-
losophy, the whole world has steadily realized
that between matter and energy on the one
hand, and space and time on the other, there
is a real and highly significant difference.2

1 An excellent account of this period may be found in
Merz's "History of European Thought in the Nineteenth
Century," Vol. II, Chap. VII, "On the Physical View of
Nature."

2 For a brief statement of Kant's argument see Royce,
"The Spirit of Modern Philosophy," pp. 121-125.

20 THE FITNESS OF THE ENVIRONMENT

But, however important such distinctions may
be for the philosopher, the man of science in
his practical task is obliged to put them
aside and to make the best of whatever evi-
dence experience, observation, and experi-
ment may supply. Out of such studies space
and time have emerged, usefully defined by
mathematical criticism as substantial parts
of the edifice of science.1

There is no small difficulty in the exposi-
tion of modern critical results regarding
space and time, but fortunately there is little
need of considering them on the present
occasion. For in spite of all assaults of phi-
losophers and mathematicians space remains
for practical purposes more certainly than
ever the Euclidian space of the ancients,
only it has become somewhat richer in char-
acteristics. And time is now and forever
that which flows equably, wholly independ-
ent of all else, though almost all else is
dependent upon time. It is Euclidian space
in which the earth moves and describes its
ellipse, parallel rays of light never do meet
in our practical experience, and our crystals

1 The works of Poincare, "La Science et l'Hypothese," "La
Valeur de la Science," and "Science et Methode," published
by Flammarion, may be consulted for a popular statement of
such mathematical studies.

FITNESS 21

are in form the figures of Euclidian geometry.
Our time flows ever in proportion to the
swings of a pendulum, the propagation of
light, and the progress of a chemical change.
Time and space are thus bound to matter
and energy by experience, and for practical
purposes we accept all four as science at
present knows them.1 We cannot doubt
that knowledge of them will increase and
ideas of them change. But we can scarcely
think that our present ideas are inadequate
for our present purposes, or that, for life,
matter will ever be other than the elements
of the periodic classification, energy that set
of quantities to which we apply the laws of
thermodynamics, and time and space the
concepts which were familiar to Galileo and
Euclid.

IV

THE ORGANISM

Thus the growth of physical science has
provided the speculative biologist with a
very accurate and extensive description of
the physico-chemical structure of the ma-
terial universe and with a well-founded con-

1 In the present work we need have no concern for the
so-called principle of relativity.

22 THE FITNESS OF THE ENVIRONMENT

fidence in his right to make use of the descrip-
tion in investigating the relationship between
life and the environment.

The biologist studies living organisms as
inhabitants of this world, and by holding
fast to physics and chemistry he has created
modern physiology, a science which unites
many, indeed nearly all, of the departments
of physics and chemistry in the task of de-
scribing the processes of life.

That task has proved an arduous one, even
in comparison with the other enterprises of
science, and it must be confessed that few
of the departments of physiology wear an
aspect of finality which has long been famil-
iar in such sciences as mechanics and crystal-
lography, for example. Yet, as time has
passed, and the nature of the material basis
of life and the conspicuous features of the
mechanism which the organism presents for
study have become more familiar, assurance
has steadily grown of the possibility of decid-
ing upon fundamental and essential char-
acteristics of the life process. No doubt
opinions have fluctuated, and in different
periods of the history of science particular
phenomena of living organisms have been
examined, criticized, and then well-nigh for-
gotten. But gradually ideas, ever more and
more precise, have arisen and been accepted.

FITNESS 23

Until very recent times, however, the
main interest has centered upon morpho-
logical problems and upon the processes of
growth and development. The ancient con-
troversies regarding types and homologous
parts, the question of spontaneous genera-
tion and the whole science of embryology,
and inquiries into the nature of fermentation
and the role of microorganisms are examples
of the older tendencies. Such interests have,
it need hardly be said, lost none of their im-
portance, but they scarcely touch the physico-
chemical problem of the nature of living
things. Yet there is in these subjects one
point of view, a favorite of Cuvier's, now,
though still familiar, less often emphasized,
which states a most important characteristic
of life in terms of matter and energy, space
and time.1 Living things preserve, or tend

1 "La vie est done un tourbillon plus ou moins rapide,
plus ou moins complique, dont la direction est constante,
et qui entrafne toujours des molecules de memes sortes, mais
ou les molecules individuelles entrent et d'ou elles sortent
continuellement, de maniere que la forme du corps vivant
lui est plus essentielle que la matiere." ("Regne animal,"
p. 13, etc.) "II vient sans cesse des elements du dehors en
dedans : il s'en echappe du dedans en dehors : toutes les par-
ties sont dans un tourbillon continue!, qui est une condition
essentielle du phenomene, et que nous ne pouvons suspendre
longtemps sans l'arreter pour jamais. Les branches les plus
simples de l'histoire naturclle participent deja a cette compli-

ft C State College

24 THE FITNESS OF THE ENVIRONMENT

to preserve, an ideal form, while through
them flows a steady stream of energy and mat-
ter which is ever changing, yet momentarily
molded by life; organized, in short. This
idea, to which we must later return, could
not possess in the early nineteenth century
the significance and value which now attach
to it. It needed the explanation which the
study of metabolism has at length provided.

METABOLISM

Metabolism is the term applied to the in-
flow and outflow of matter and energy and
their intermediarv transformations within the
organism. Its serious investigation began
with Lavoisier, the principal founder of mod-
cation et a ce mouvement perpetuel, qui rendent si difficile
l'applieation des sciences generates. " (" Rapport,'5 p. 150, etc.)
" Dans les corps vivans chaque partie a sa composition propre
et distincte ; aucune de leurs molecules ne reste en place ;
toutes entrent et sortent successivement : la vie est un tour-
billon continuel, dont la direction, toute compliquee qu'elle,
est, demeure constante, ainsi que l'espece des molecules qui
y sont entrainees, mais non les molecules individuelles elles-
memes. . . . Ainsi la forme de ces corps leur est plus
essentielle que leur matiere," etc. (Ibid. p. 200.) — " Eloges
historiques," Vol. I, p. 200. Quoted by Merz, "A History of
European Thought in the Nineteenth Century," Vol. I, p.
129. Edinburgh and London, 1898.

FITNESS 25

ern chemistry, who by ingenious experiments
discovered that the essential feature of the
chemical process in the animal is combus-
tion or oxidation, and that the amount of oxy-
gen required by such combustion is not much
less than that needed to burn substances which
resemble the foods in the air. The problems
which thus arose have been studied by a
host of later investigators, notably by Liebig
and Voit, and gradually a vast array of facts
concerning the turnover of matter and en-
ergy in the body have been accumulated.
Among other achievements is the proof that
the principle of the conservation of energy
applies to the living organism. These have
been chemical investigations, carried out by
chemists, and for that reason, until quite
recently, they have not received their due
in general biology.

Meantime, as knowledge of the balance
sheet of the body, the total metabolism so-
called, has been perfected, more and more
interest has developed in the changes which
attend the passage of matter and energy in
their various stages through the organism.
Such problems at once demand a physico-
chemical description of protoplasm as a nec-
essary basis for their solution. The same
demand has also arisen in other quarters.

26 THE FITNESS OF THE ENVIRONMENT

Thus the microscope, with all its brilliant
contributions to knowledge of the form and
more gross structural elements of the cell,
hardly at all contributes to knowledge of its
physico-chemical organization as a mechan-
ism. Out of such needs a preliminary, if
very imperfect, rational description of proto-
plasm has arisen, and gradually the physical
and chemical laws governing protoplasm, its
form, composition, and stability, its con-
stituent parts and their mode of action, and
the physical and chemical changes within
it are being discovered.1 The idea of dur-
able form in matter and energy that change
can now be applied to the cell with greater
advantage, in that descriptions of the form
and of the change are now at hand, though
as yet all too imperfect.

Another profoundly important contribu-
tion of the science of metabolism to our
knowledge of the characteristics of life is the
discovery of the cycle of matter through
plants and animals.2 The plant takes up
carbonic acid and water and a few other
simple substances from air and soil, and

1 This subject is extensively treated by Hober, "Physik-
alische Chemie der Zelle und der Gewebe." Leipzig, 1911,
3d ed.

2 This was originally clearly stated by Lavoisier.

FITNESS 27

transforms them into oxygen, which renews
the air, and sugar, starch, and other sub-
stances, which are the food of the animal.1
These products the animal burns, thereby
forming once more carbonic acid and water,
which return to the plant and so pass through
the cycle again and again. The changes in
energy which accompany this process are
quite different from the chemical changes.
Starch and sugar and oxygen, formed in the
leaf of the plant, are compounded of carbonic
acid, water, and sunshine. This sunshine,
or solar energy, wh'en changed into the
chemical energy of the carbohydrate, is pre-
served and transmitted to the animal.2 In
his body it is set free as muscular force and
heat, and then dissipated. Accordingly, when
carbonic acid and water are combined to
form sugar and oxygen in the leaf, it is al-
ways a new store of solar energy which they
bear, and while matter goes round and
round, energy is being constantly degraded
and lost. The one process is cyclic, the
other moves steadily in one direction from

1 Our knowledge of photosynthesis is largely based upon
the classical work of N. T. de Saussure, "Recherches Chi-
miques sur la Vegetation." Paris, 18(U.

2 Only after the establishment of the principle of the
conservation of energy was it possible to gain a clear con-
ception of the energetics of metabolism.

28 THE FITNESS OF THE ENVIRONMENT

sunshine to the waste heat of the animal
body.1

B

ORGANIC CHEMISTRY

Independent alike of general biology and
of the science of metabolism there has grown
up still another department of natural sci-
ence, organic chemistry, which contributes
very materially to the description and com-
prehension of living things. During a large
part of the nineteenth century the efforts of
chemists were mainly directed to the cultiva-
tion of this subject, which seeks to describe
the molecular constitution of all the com-
pounds of carbon, including nearly all the
individual substances which make up animals
and plants. Gradually, as organic chemis-
try has progressed, very complete descrip-
tions of the atomic groupings within the
molecules of fats,2 carbohydrates,3 and pro-

1 Here, as in so many other cases, it is not the conservation
of matter and energy, but the conservation of matter and the
degradation of energy which are important. For an exten-
sive development of this important difference see B. Brunhes,
"La Degradation de l'Energie." Paris, 1909.

2 Chevreul, "Recherches Chimiques sur les Corps Gras."
Paris, 1823.

3 E. Fischer, " Untersuchungen liber Kohlenhydrate und
Fermente." Berlin, 1909.

FITNESS 29

teins,1 the chief of such things, and most
of the other biologically important sub-
stances have been obtained, and we are at
length in possession of exceedingly clear and
reliable ideas as to the chemical constitu-
tion of living matter. In fact, the nature
and laws of the chemical composition of pro-
toplasm are actually more certain than the
nature and laws of its physical structure.2

In this manner, by slow degrees, the de-
scription of living things has progressed, and
gradually the characteristics of life have
become less obscure and their aspects more
simple. It cannot be denied that many
traits like consciousness and inheritance are,
at least for the present, beyond the scope of
description in terms of matter and energy,
and the fundamental riddle shares this de-
tachment.3 But the physico-chemical basis

1 E. Fischer, " Untersuchungen iiber Aminosauren, Poly-
peptide und Proteine." Berlin, 1906.

2 Substantial progress in the latter field is nearly all of
very recent date, almost wholly since the sudden rise of
physical chemistry.

3 "But now, having confessed that Life as a principle of
activity is unknown and unknowable — that while its phe-
nomena are accessible to thought the implied noumenon is
inaccessible — that only the manifestations come within the
range of our intelligence while that which is manifested lies
beyond it ; we may resume the conclusions reached in the
preceding chapters. Our surface knowledge continues to be

30 THE FITNESS OF THE ENVIRONMENT

of life is firmly established in the world of our
senses. On the whole the composition of
living matter, its physical structure, the
changes of matter and energy which consti-
tute the metabolic process, together with the
totality of such changes, which make up the
fundamental economic process of that largest
community which consists of all living beings,
are all clearly defined.

C

THE CHARACTERISTICS OF LIFE

Under the circumstances it is certainlv no

t/

rash enterprise to seek a definition of some
of the essential characteristics of life. Al-

a knowledge of its kind, after recognizing the truth that it is
only a surface knowledge.

"For the conclusions we lately reached and the definition
emerging from them, concern the order existing among the
actions which living things exhibit ; and this order remains the
same whether we know or do not know the nature of that
from which the actions originate. We found a distinguish-
ing trait of Life to be that its changes display a correspond-
ence with coexistences and sequences in the environment;
and this remains a distinguishing trait, though the thing
which changes remains inscrutable. The statement that
the continuous adjustment of internal relations to external
relations constitute Life as cognizable by us, is not invali-
dated by the admission that the reality in which these rela-
tions inhere is incognizable." — Herbert Spencer, "The
Principles of Biology." New York and London, 1909, Vol.
I. Revised and enlarged edition, pp. 122-123.

FITNESS 31

though it is probably far beyond our present
power to make a complete study of the prob-
lem, I feel sure that a brief analysis will
justify certain very definite conclusions. Life
as we know it is a physico-chemical mechan-
ism, and it is probably inconceivable that it
should be otherwise.1 As such, it possesses,
and, we may well conclude, must ever pos-
sess, a high degree of complexity, — physi-
cally, chemically, and physiologically; that is
to say, structurally and functionally. We
cannot imagine life which is no more complex
than a sphere, or salt, or the fall of rain, and,
as we know it, it is in fact a very great deal
more complex than such simple things. Next,
living things, still more the community of
living things, are durable. But complexity
and durability of mechanism are only pos-
sible if internal and external conditions are
stable. Hence, automatic regulations of the
environment and the possibility of regulation
of conditions within the organism are essen-
tial to life. It is not possible to specify a
large number of conditions which must be
regulated, but certain it is from our present
experience that at least rough regulation of

1 I mean, of course, for the purposes of physical and chem-
ical study. With such qualifications the statement is prob-
ably no longer open to objection from any quarter.

32 THE FITNESS OF THE ENVIRONMENT

temperature, pressure, and chemical consti-
tution of environment and organism are
really essential to life, and that there is great
advantage in many other regulations and in
finer regulations. Finally, a living being must
be active, hence its metabolism must be
fed with matter and energy, and accordingly
there must always be exchange of matter
and energy with the environment.

Returning to the concept of the organism
as a durable form through which flow matter
and energy, it is now possible to make these
ideas more vivid. The complex structure of
the living being is relatively stable, alike in
the chemical composition of its individual
constituent molecules, in their proportions
and amounts, in their aggregation into the
invisible structural elements of protoplasm,
in the visible parts of the cell, in the organs
and tissues, and finally in toto, as a man or a
tree. Similarly stable are the physical con-
ditions within this structure: temperature,
pressure, alkalinity, and osmotic pressure.
Finally, that which surrounds it, the imme-
diate environment, possesses also a high de-
gree of stability, or if the organism be very
complex, it may be that it has an efficient pro-
tection against change of environment; a skin
which insulates, for instance. But in this case

FITNESS 33

it has also acquired an environment, a milieu
interieur for its cells, — like the blood and
lymph, — which serves the same purpose as
stability of the external environment, and ex-
ercises the further function of supplying food.

It is through this structure, in the process
of metabolism, that matter and energy flow.
Entering in various forms and quantities,
they are temporarily shaped exactly to the
form and condition of the organism; they
conform to the characteristics of the king-
dom, class, order, family, genus, species, and
variety to which it belongs, and they assume
even the characteristics of the individual
itself.1 Then they depart through the va-
rious channels of excretion.

When these ideas are reduced to their very
simplest forms, it appears that life must be
highly complex in structure and function;
that the conditions of the environment must
be regulated, and that there must be very exact
regulation of conditions, both structural and
functional within the organism, and finally,
that, while life is active, there must be ex-
change of both matter and energy with the
environment. Complexity, regulation, and
food are essential to life as we know it, and

1 Science is, of course, still at a loss for an adequate gen-
eral explanation of such processes.

3-t THE FITNESS OF THE ENVIRONMENT

in truth we cannot otherwise conceive of life,
or indeed of any other durable mechanism.
For my part I do not doubt that these pos-
tulates are quite as true of the world of our
senses as are the fundamental laws of matter
and energy, space and time.

Obviously these few conclusions can make
no claim to completeness. Fully to describe
life, the discovery of many other fundamen-
tal characteristics is necessary, including such
as are related to inheritance, variation, evo-
lution, consciousness, and a host of other
things. But in the formation and logical
development of such ideas there is danger
of fallacy at every step, and since the present
list will suffice for the present purpose, further
considerations of this sort are best dispensed
with. This subject should not be put aside,
however, without clear emphasis that the
postulates which have been adopted above
are extremely meager. The only motives for
abandoning further search are the economy
and the security which are thus insured, and
the very great difficulty of extending the
list. Any one who is familiar with similar
efforts to elucidate the essential character-
istics of life, such as that of Wallace,1 cannot,
I fear, fail to perceive the extreme limitations

1 A. R. Wallace, "Man's Place in the Universe." New

FITNESS 35

which are imposed upon inquiry by assuming
complexity, regulation, and metabolism ex-
clusively. Perhaps in reality these postu-
lates are only two. Metabolism might with-
out difficulty be included under regulation,
but the consideration of such purely logical
questions is beside the present purpose.
However, these are probably the character-
istics of the organism which are best fitted for
discussion in relation to the physico-chemical
phenomena of matter and energy, and it is
barely possible that no others bear the same
simple relations to the outside world.

York, 1903, Chaps. X and XI, especially the following
statement : —

"The physical conditions on the surface of our earth
which appear to be necessary for the development and main-
tenance of living organisms may be dealt with under the fol-
lowing headings : —

" 1. Regularity of heat supply, resulting in a limited range
of temperature.

"2. A sufficient amount of solar light and heat.

" 3. Water in great abundance, and universally distributed.

"4. An atmosphere of sufficient density, and consisting of
the gases which are essential for vegetable and animal life.
These are Oxygen, Carbonic-acid gas, Aqueous vapor, Ni-
trogen, and Ammonia. These must all be present in suitable
proportions.

"5. Alternations of day and night."

It must be remembered, however, that such conclusions
depend upon reasoning from analogy, a dangerous proceed-
ing.

36 THE FITNESS OF THE ENVIRONMENT

THE PROBLEM

We may now return to the problem of the
fitness of the environment. So long as ideas
of the nature of living things remain vague
and ill-defined, it is clearly impossible, as a
rule, to distinguish between an adaptation of
the organism to the environment and a ease
of fitness of the environment for life, in the
very most general sense. No doubt there
are clear instances of both phenomena which
require no close analysis for their interpreta-
tion. Thus the hand is surely an instance
of adaptation, and the anomalous expansion
of water on cooling near its freezing point
an instance of environmental fitness. But
how much weight is to be assigned to adapta-
tion and how much to fitness in discussing the
relations between marine organisms and the
ocean ? Evidently to answer such questions
we must possess clear and precise ideas and
definitions of living things. Life must by ar-
bitrary process of logic be changed from the
varying thing which it is into an independ-
ent variable or an invariant, shorn of many
of its most interesting qualities to be sure,
but no longer inviting fallacy through our

FITNESS 37

inability to perceive clearly the questions
involved.

Such is the purpose, and the justification,
for setting up the postulates of complexity,
regulation, and metabolism as inherent in
that mechanism which is called the living
organism. With them, at length, we face
the problem which awaits us. To what ex-
tent do the characteristics of matter and
energy and the cosmic processes favor the
existence of mechanisms which must be com-
plex, highly regulated, and provided with
suitable matter and energy as food ? If it shall
appear that the fitness of the environment to
fulfill these demands of life is great, we may
then ask whether it is so great that we can-
not reasonably assume it to be accidental,
and finally we may inquire what manner
of law is capable of explaining such fitness of
the very nature of things.

CHAPTER II
THE ENVIRONMENT

ASTRONOMY

AN examination of the relationship be-
tween life and the environment, in which
by means of the simplifying postulates pre-
viously developed life is arbitrarily taken as
an invariant, should, if it is to be quite general,
rest upon a physico-chemical description of
the whole universe. We require to know the
form and structure of stars and of interstellar
space, of nebulae and of solar systems, and
the conditions and changes which accompany
such aggregations of matter. Evidently this
requirement can be but imperfectly fulfilled,
and yet one need not be too apologetic in
venturing the attempt. In the end, to be
sure, we shall found our argument upon the
safe basis of terrestrial phenomena, but mean-
time it will be an advantage to consider con-
ditions far and wide.

S8

THE ENVIRONMENT 39

The science of cosmography is probably
the earliest of all the natural sciences, and
cosmological speculation appears to accom-
pany it from the outset. Long before the
dawn of history the Chaldeans possessed
much accurate information about the stars,
and the zodiac was known to the Egyptians
not less than fifteen centuries before our era.
Always pursued with great interest, such studies
received their first provisional systematic for-
mulation at the hands of Hipparchus in the
second century B.C. He, the greatest of the
astronomers of antiquity, succeeded in bring-
ing the apparent movements of the sun, moon,
and planets into an arbitrary scheme which
was nearly perfect for the sun, though less
so for the other movable celestial bodies. He
also measured and catalogued the positions
of a large number of fixed stars. Upon this
secure foundation of quantitative observa-
tions modern astronomy has built. At the
beginning of the modern period Copernicus,
Tycho Brahe, Kepler, Galileo, and Newton
reduced the phenomena of the solar system
to law. At a later day speculations based
upon their results and upon growing knowl-
edge of physics and chemistry led Thomas
Wright, Kant, and finally Laplace to a ra-
tional, if somewhat imperfect, cosmological

40 THE FITNESS OF THE ENVIRONMENT

theory of the solar system. Finally, ever
more accurate observations and the marvel-
ous fertility of spectroscopical investigations
have brought the stars within our reach.

The whole universe now appears to be not
unlike our part of it, both chemically and
physically. The same forms of matter, the
same material aggregates, the same manifes-
tations of energy, and similar movements are
everywhere present. The stars are no longer
changeless, but violently active bodies ; they
are no longer permanent, but evolving sys-
tems; they are born, they grow, age, and
die; and throughout their evolution they
obey laws, which, though as yet imperfectly
known, appear to be common to all. Mean-
time the study of nebulae, comets, and meteor-
ites has kept pace with other departments of
the science, and our interpretation of the re-
sults of stellar astronomy1 constantly gains
from ever increasing knowledge of the physical
and chemical processes in the sun.

The universe which thus gradually has been
revealed to the astronomer is made up of a
relatively small number of types of material

1 A description of such facts from the physico-chemical
point of view may be found in Arrhenius's "Lehrbuch der
kosmichen Physik." Leipzig, 1903. A brief popular account
f some of the facts in the same author's "Worlds in the Mak-
ing," translated by Borns. New York and London, 1908.

THE ENVIRONMENT 41

aggregation. These include luminous dense
bodies like the sun and stars ; non-luminous
dense bodies like the earth, the moon, the
planets, and invisible partners of certain stars ;
nebulae, comets, and meteorites. The larger
of these bodies are separated by vast extents
of space which contain only rare meteorites,
perhaps minute traces of gaseous material,
and cosmic dust. There can be little doubt
that other types of bodies do not commonly
occur in that portion of the universe which is
open to astronomical investigation. Both the
enormous collections of astronomical data
which are now at hand and the beginnings
of clear knowledge of cosmic processes justify
this belief. Of what may lie beyond the
visible stars we can, of course, know nothing.

The nature of the stars is revealed to us
chiefly by study of their spectra, according
to which they have been roughly classified,
by Vogel * for example, quite simply into
three principal types.

I. White stars in which there is marked
evidence of the presence of hydrogen, or, in
some instances, helium. The stars of this
class undoubtedly are extremely hot, the
helium stars probably especially so. Their
atmospheres seem to be very dense and to

1 See Arrhenius's "Lehrbuch," pp. 23-27.

42 THE FITNESS OF THE ENVIRONMENT

consist of hydrogen or helium or a mixture
of the two gases. There is evidence that some
of these stars possess very high rotational
velocities.

II. Yellow stars, including the sun, whose
spectra indicate the presence of hydrogen and
numerous metals, — sodium, iron, calcium,
magnesium, etc. The lines which show the
presence of hydrogen in the stars of this type
vary in intensity. The current belief is that
those stars which appear to possess more
hydrogen are the hottest. The stars of this
type are less hot than those of type I.

III. Reddish stars whose spectra show little
or no sign of the presence of hydrogen, but
indicate that of chemical compounds, in-
cluding hydrocarbons. The presence in these
spectra of the lines of sodium, iron, calcium,
and magnesium is clearly established. Stars
of this type are evidently the coolest of lumi-
nous dense bodies.

This classification is, of course, provisional
and unsatisfactory, and probably sometimes
results in bringing together relatively unlike
stars and in separating such as are very much
akin. Moreover, subdivisions in the classifica-
tion are necessary and hard to make. Other
better but more complex classifications appear
to exist, but they suffer only in less degree

THE ENVIRONMENT [.',

from like defects. In short all the known
facts can best be explained by the assump-
tion that the stars represent different stag -
of development of suns.1 In that case this

1 "Bei Durchmusterung der Specktra der verschiedenen
Sterne kann man sich nicht des Gedankens erwehren, dasa
die verschiedenen Sterngruppen verschiedenen Entwick-

lungsstadien entsprechen. Die jiingsten mid wiirmsten
aller Sterne waren (nach der allgemeinen Ansiclit, vgl. weiter
unten Kap. Kosmogonie) diejenigen der ersten Gruppe.
Das kontinuierliche Licht, welches von dem eigentlichen
Sternkorper ausstrahlt, riihrt haupstachlich von Kondensa-
tionen, wolkenartigen Bildnngen in der Atmosphiire der
Sterne, zum geringeren Teil von den stark verdiehteten
Metalldampfen im Inneren des Sterns her. In den hoheren
Schichten dieser Atmosphiire finden sich die leichten Gase,
Wasserstoff oder Helium oder alle beide, weiter unten Metal 1-
dampfe. Bei den Sternen erster Klasse ist die Atmosphiire
der leichten Gase so dick und heiss, dass die fur uns sicht-
baren Kondensationen beinahe alle in diesen oberen Schichten
vor sich gehen. Wir sehen deshalb keine oder nur schwache
Metalllinien, dagegen sehr starke Wasserstoff- oder Helium-
linien. Bisweilen ist die Menge und Temperatur der Leichten
Gase geniigend, um helle Umkehrungen dieser Linien zu
verursachen. Bei dem zweiten Spektraltypus ist die Ab-
kiihlung weiter fortgeschritten, so dass Kondensationen
nicht nur in den hochsten Schichten der Atmosphiire, sondern
auch innerhalb der Metallatmosphiire vorkommen. Man
sieht dann die dunklen Metalllinien scharf hervortreten. Das
Zuriicktreten des violetten Endes des Spcktrums und einige
schwache Bander im roten Teil deuten auf niedrigere Tem-
peratur hin. Bei den rotliehen Sternen treten tiefe Temper-
atur andeutende Erscheinungen noch mehr hervor. Die bei
denselben gewohnlich vorkommende Verttnderlichtkeit liisst
auf das Vorkommen von kalteren und wiirmercn Perioden

44 THE FITNESS OF THE ENVIRONMENT

development or evolution must be a contin-
uous process through which every sun slowly
passes, and on the whole all suns must be
much alike. Certainly we have the best of
evidence to justify the assumption that most
stars, including the sun, have very much the
same chemical composition, and that differ-
ences in spectra are due to the slowly progress-
ing physico-chemical changes which have
accompanied the process of cooling.

Needless to say, the chemical composition
of the sun itself is far better known than that
of the stars. Particularly prominent among
his constituent elements are those above
mentioned: hydrogen, sodium, calcium, mag-

schliessen, wie solche in geringerem Maasstab bei unserer
Sonne durch die Fleckenperiode sich kundgeben. Zuletzt
wird die Leuchtkraft der Sterne sehr schwach und das Licht
ausgepragtrot, der relativ niedrigen Temperatur entsprech-
end. Nach diesem Stadium kommt dasjenige, worin die
dunklen ultraroten Strahlen allein herrschen, der Stern ist in
einen nichtleuchtenenden Himmelskorper Ubergegangen (vgl.
weiter unten Kap. Kosmogonie).

Im Grossen und Ganzen zeigen die Sterne dieselbe chemi-
sche zusammensetzung wie die Sonne. Die hervorragende
Rolle des Wasserstoffs und Heliums, sowei des Eisens, Na-
triums, Calciums und Magnesiums, macht sich iiberall be-
merkbar. Es ist dann kein Zweifel, dass unsere Sonne mit
den Fixsternen sehr nahe verwandt ist, und zwar ist sie als
ein Fixstern der ersten Abteilung in der zweiten Klasse an-
zusehen." — Arrhenius, "Kosmische Physik." Leipzig,
1903, p. 27.

THE ENVIRONMENT 45

nesium, and iron. Also some others, which
because of their low density are concentrated
near the surface, are known to occur. The
elements which have not yet been discovered
are those like the metalloids which do not un-
der ordinary circumstances give well-marked
spectra, and those like gold, platinum, and
mercury, whose higher specific gravities may
be supposed to cause their accumulation in
the interior. Carbon is certainly present,
and almost certainly oxygen as well. Indeed
it is only reasonable to conclude, as Kirchhoff
originally suggested,1 that all the elements

1 "Diese Vorstellung von der Beschaffenheit der Sonne
stimmt mit der von Laplace begrlindeten Hypothese liber
die Bildung unseres Planetensystems uberein. Wenn die
Masse, die jetzt in den einzelnen Korpern dieses Systems
verdichtet ist, in fruheren Zeiten einen zusammenhangenden
Nebel von ungeheurer Ausdehnung bildete, durch dcssen
Zusammenziehung Sonne, Planeten und Monde entstanden
sind, so mussten alle diese Korper bei ihrer Bildung im
wesentlichen von ahnlicher chemischer Zusainmensetzung
sein. Die Geologic hat gelehrt, dass die Erde einst in glii-
hend fliissigem Zustande sich befundcn hat ; man muss anneh-
men, dass auch die anderen Korper unseres Systems einmal
in einem solchen gewesen sind. Die Abkiihlung, die infolge
der Ausstrahlung der Warme bei alien eingetreten ist, hat
aber bei ihnen sehr verschiedene grade erlangt ; und wiihrend
der Mond kalter als die Erdegeworden ist, ist die Temperatur
des Sonnenkorpers noch nicht unter die Weissgllihhitze
gesunken. Die irdische Atmosphare, die jetzt nur wenige
Elemente enthalt, musste, als die Erde noch gliihte, eine viel
mannigfaltigere Zusammensetzung haben ; alle in der Gliih-

46 THE FITNESS OF THE ENVIRONMENT

are present in the sun, and very often, at
least, in the stars. Exceptions may arise, but
probably they will hardly suffice to invalidate
the rule.

The large, dark, dense bodies which are
directly known to us are the planets and
their satellites. There are, however, many in-
dications that the heavens are occupied by
great numbers of "dead" suns, incrusted and
therefore no longer luminous. Such appear
to be the only conclusions which can be drawn
from a study of the energetics of solar evolu-
tion, for sooner or later a sun must cool from
loss of energy until at length a crust forms, and,
barring catastrophe, it must then endure for-
ever. Moreover, as we have seen, the varying
aspects of the stars seem to disclose suns in
all stages of such a process.

More nearly direct is the evidence furnished
by study of variable stars of the Algol type.
Algol itself Q8 Persei) is a star of second
magnitude with a period of 2 days, 20 hours,
48 minutes, 53.8 seconds. During each period

hitze fliichtigen Stoffe mussten in ihr vorkommen. Eine
entsprechende Beschaffenheit muss heute noch die Atmosphare
der Sonne besitzen." — G. Kirchhoff, — " Untersuchungen
iiber das Sonnenspektrum und die Spektren der Chemischen
Elemente." Abhandlungen der Koniglichen Akademie der
Wissenschaften zu Berlin, 1861. Zweite, durch einen An-
hang vermehrte Ausgabe. Berlin, 1862.

THE ENVIRONMENT 47

for about 2j days it shines with constant in-
tensity; thereupon it begins to decline and in
approximately 4^ hours sinks to its minimum
of brightness; then it becomes gradually
brighter until after 4^ hours more it has re-
attained its full brilliancy. This behavior is
explained by the supposition that Algol is
accompanied by a dark star and that their
movements are such that a partial eclipse
occurs every 69 hours. Pickering has suc-
ceeded in calculating, upon the assumption
that the dark star as a whole intercepts the
rays of Algol, the approximate sizes, veloci-
ties, and orbits of these two stars, one of
which is quite invisible. Many similar phe-
nomena lead to similar conclusions regarding
other variable stars.

It is apparent that such dark bodies, whether
extinct suns or planets, represent another
stage in celestial evolution. Their past his-
tories may be various, for there is still room
for much doubt as to the manner of formation
and origin of planets, but at any rate all are
probably derived from luminous stars or
planets through the process of cooling, with
its accompanying crust formation. Like their
earlier forms, they must therefore be made up
of matter as we know it, since when a heavenly
body puts on a crust, it does not change the

48 THE FITNESS OF THE ENVIRONMENT

matter of which it is composed. Finally
terrestrial chemistry completes the evidence
regarding the composition of such astronom-
ical bodies; geophysics that regarding their
state. The number of extinct suns is prob-
ably very great ; Arrhenius thinks it not un-
likely that they may be one hundred times
more numerous than the luminous stars.1

It is more difficult to gain a clear idea of
the nebulae, for such aggregations of matter
are very diverse in appearance, and none lie
near enough to the earth for us to study them
as we study the solar system. However, in-
vestigation of new stars, of the spiral forms of
many nebulae, of the so-called star rifts
which appear to be due to the movement of a
large body through a nebula, sweeping up
smaller bodies and leaving a channel behind,
and a variety of considerations dependent
upon the modern development of the sciences
of physics and chemistry, all contribute to a
growing belief that nebulae may often, and
sometimes at least do certainly arise from col-
lisions between dense bodies. Further, the
nature of the processes by which stars may be
formed out of nebulae becomes constantly
better understood, and while there is small
ground to regard our present science of nebulae

1 " Worlds in the Making," p. 151.

THE ENVIRONMENT 49

as final, there is none at all for the belief
that anything essentially inexplicable either

physico-chemically or genetically will be dis-
covered in their organization.

Putting aside all contentious matters, it is
abundantly clear that nebulae, however they
may vary among themselves, are made up of
vast extents of gaseous material and dust
which are exceedingly rare and at very low
temperature, and that they may contain all
kinds of foci of condensation, from stars to
meteorites, in great variety of forms and
conditions.

On the whole the common-sense judgment
that the solar system may be taken as a fair
sample of the universe, and that its probable
evolution is in the main typical of cosmic
evolution in general seems to be well founded.
Any other hypothesis does violence to a host
of facts, and to the larger generalizations of
modern science.

n

POSSIBLE ENVIRONMENTS

If now we seek to make the best of existing
astronomical knowledge, as hastily sketched,
in the study of our biological problem, cer-
tain considerations at once present themselves*

50 THE FITNESS OF THE ENVIRONMENT

Obviously it is not everywhere in such a uni-
verse that life can exist. The visible stars,
like the sun, certainly cannot support life.
Throughout such bodies durable and complex
arrangements of matter are impossible, for if
formed, they must be at once dissipated by
catastrophes far greater than any which can
occur upon the earth's crust. The enormous
intensity of heat, even in the most superficial
parts of suns, must effectually preclude any
state of matter but the gaseous, and thus
prevent the existence there of anything of
the nature of a mechanism. Such bodies,
apart only from continuous variation from
center to periphery, in the proportions of the
elements, in density, and in the nature of the
chemical unions between the elements, must be
essentially homogeneous. They can scarcely
possess relatively as much structure as the
earth's atmosphere. In truth the sun itself
seems to be the one and only durable solar
mechanism.

Not less evident is the impossibility of active
life in interstellar space or in nebulae. Dor-
mant life (panspermia) may indeed be possible
universally, except only in the neighborhood
of suns. But if life is to be fed, if there is to
be active metabolism, including exchange of
matter with the environment, something more

THE ENVIRONMENT 51

nourishing than the rare molecules of a nebula,
or the still rarer particles of interstellar space,
must be provided.

We may safely conclude, therefore, on the
basis of our reliable knowledge of the universe,
that active life can exist probably only upon
a dense, crusted body1; for, of course, the in-
terior of the earth is no better suited to life
than is the interior of the sun.

We have perhaps taken a long road to arrive
at so familiar an idea. But our task involves
the consideration of every conceivable form
of life, not merely that relatively anthropo-
morphic kind which we commonly think
of when speculating loosely regarding life in
other worlds.

It is indeed possible that the common-sense
judgment of the universe which declares our
solar system to be on the whole, in its funda-
mental characteristics, typical of every such
system may turn out to be in some respects
unjustified. For the present, however, so
long as we use it only as an indication of the
direction in which we are to turn our atten-
tion, there is certainly no risk whatever in fol-
lowing this hypothesis in the later discussion.

1 For an interesting discussion of the necessary conditions
of existence see P. Lowell, "Mars as the Abode of Life."
The Macmillan Company, New York, 1908.

52 THE FITNESS OF THE ENVIRONMENT

III

GEOPHYSICS

Let us, accordingly, now examine such
phenomena as are likely to occur upon the
surfaces of bodies which in the course of
cosmic evolution have acquired a solid crust.
In faithfully carrying out such a plan, the
sciences of geology and meteorology must be
brought under contribution, and climatic
conditions must receive especial attention.
Not, to be sure, that our globe in every respect
can fairly be taken as meteorologically typical
of all incrusted bodies. On the contrary, there
are a large number of phenomena which are
unquestionably of highest significance in fa-
voring the existence of life on this particular
planet which appear to be accidental and prob-
ably somewhat uncommon.1 Such are the

1 These also have been favorite subjects in the works on
natural theology. The Bridgewater Treatises of Whewell
and of Prout are replete with illustrations, those of Whewell
often moderately expounded, while Prout's are, as a rule, most
curious and antiquated.

"Lastly, who will venture to assert that the distribution
of sea and of land, as they now exist, though apparently so
disproportionate, is not actually necessary as the world is
at present constituted ? What would be the result, for
instance, if the Pacific or the Atlantic oceans were to be con-
verted into continents ? Would not the climates of the exist-

THE ENVIRONMENT 53

size of the sun taken in relation with its dis-
tance from the earth ; the size of the earth,
which enables it to retain its present atmos-
phere; the eccentricity of its orbit and the
inclination of the ecliptic; the relative
amounts of land and sea, and a host of other
factors. Together these probably make of
the earth, in comparison with other bodies,
an extremely favorable abode for the living
organism. Yet it cannot be denied that in
detailed chemical constitution the earth is
certainly more or less typical of all similar
bodies. Moreover the earth's crust and its
atmosphere, being formed in accordance with

ing continents, as formerly observed, be completely changed
by such an addition to the land, and the whole of their fertile
regions be reduced to arid deserts ? Now, this distribution
of sea and of land, so wonderfully adapted as it appears to
be to the present state of things, depends of course in a great
measure upon the absolute quantity of water in the world.
While, on the other hand, the relative gravity of water, as com-
pared with that of the earth, keeps the ocean within its
destined limits, notwithstanding its incessant motion. Thus
Laplace has shown that the world would have been con-
stantly liable to have been deluged from the slightest causes.
had the mean density of the ocean exceeded that of the earth !
Hence the adjustment of the quantity of water and of its
density, as compared with that of the earth, afford some of
the most marked and beautiful instances of design." — Prout,
The Bridgewater Treatises, Treatise VIII, "Chemistry,
Meteorology, and the Function of Digestion." London, 1834,
pp. 186-187.

54 THE FITNESS OF THE ENVIRONMENT

general laws, are likewise typical or at all
events were so at the time of their origin.

Neither can the change in crust and atmos-
phere which time has wrought be wholly
unique, though here a possible exception may
again arise in the action of life itself. Since
we do not at present positively know of the
existence of life elsewhere and certainly have
no detailed knowledge of its nature, we can-
not feel sure that the conversion of atmos-
pheric carbonic acid into oxygen and coal is
either a universal or a common occurrence.
In details of the geological process indeed there
may well be marked differences. Probably the
greatest variation will occur in the relative
duration of conditions like those which we
now enjoy on the earth, the length or brevity
of the period from the full establishment of
the circulation of water by evaporation, cloud
formation, rainfall, with the flow of lakes and
streams, until its extinction by cold. Thus
there is more liability of error in an analyis
of the general characteristics of those spon-
taneous changes which must occur upon the
surface of a body after the formation of a
crust than there is in the attempt to dis-
cover the general characteristics of stellar
evolution. But here again our knowledge is
not based upon terrestrial phenomena alone.

THE ENVIRONMENT 55

With greater or less completeness and accu-
racy the atmospheres of the moon, of Mars,
and of other planets have been studied and
accounted for.

IV

THE ATMOSPHERE

Even at the earliest period in the evolu-
tion of a typical star there appears to he
a progressive variation in chemical composi-
tion from center to periphery. Theoreti-
cally it seems inevitable that the heaviest
elements should be concentrated in the interior
and that those of lowest atomic weight should
be present in greatest amount near the sur-
face. Actually, as above stated, spectro-
scopic investigation fully confirms this view.
Thus the spectra of typical hot stars show
that hydrogen is an invariable constituent
of their superficial parts. Indeed the uni-
versal presence of hydrogen under such cir-
cumstances is undoubtedly one of the most
clearly established facts of stellar astronomy.
As stars cool and become red the spectral
changes quite as unmistakably point to the
presence of carbon. Accordingly we possess
the best of evidence and the best of reasons
for the belief that large quantities of hy-

56 THE FITNESS OF THE ENVIRONMENT

drogen and carbon must exist at or near
the surface when a crust forms upon a cool-
ing star.

The nature of the chemical combinations
into which these elements at first enter is
perhaps open to some question. But as the
temperature falls in the cooling of a sun or
planet the affinities of carbon and hydrogen
for oxygen increase, so that carbonic acid and
water must normally result. For oxygen
is almost certainly present in the sun; it is
found in meteorites, and the vast store of it
in the earth's atmosphere and crust (roughly
one half of their total mass) justifies the be-
lief that it is everywhere one of the commonest
of elements. Hence an atmosphere contain-
ing water and carbonic acid appears to be a
normal envelope of a new crust upon a cooling
body. Even were not these substances at
first present in such an atmosphere, volcanoes
must soon belch them, forth in enormous
quantities to relieve the pressure which inevi-
table chemical processes set up.

It is clear that no one can give an exhaus-
tive description of the formation of the earth's
atmosphere and the changes which underlie
vulcanism, so long as the theoretical considera-
tions involved remain often more obscure than
the facts. However, be the process what it

THE ENVIRONMENT 57

may, it is at least automatic, and must repeal
itself in other similar circumstances.

There is, moreover, direct evidence in sup-
port of the above conclusions. Spectro-
scopic investigation has proved the presence
of water vapor in the atmospheres of Mars,
Venus, Jupiter, and Saturn, and nobody has
suggested what the snowcaps of Mars may be
unless they are real snow (hoarfrost) or, im-
probably, carbonic acid. Lowell and Arrhe-
nius agree in considering them snowcaps.1

In the earth's atmosphere carbonic acid has
been very largely converted into oxygen and
vegetable matter, which later has been turned
into enormous quantities of coal. It is, in
fact, possible, in accordance with the sugges-
tion of Koene, that all the oxygen of the
atmosphere has been thus formed from car-
bon dioxide, and that therefore coal, peal, and
other similar substances within the earth are
chemically equivalent to the oxygen now free.

If a typical atmosphere must contain water
and carbon dioxide, its evolution must ob-
viously be in part conditioned by the presence
of these substances. Hence terrestrial mete< >r-
ology, no less than terrestrial geology, must be
in greater or less degree a special case of a

1 Arrhenius, " Kosmische Physik," p. 173; Lowell, " Mars
as the Abode of Life," p. 81.

58 THE FITNESS OF THE ENVIRONMENT

general process, and meteorological condi-
tions on the earth cannot be perfectly
unique.

A number of circumstances, however, cause
far greater variations in meteorological pro-
cesses than in most other phenomena which
have yet been discussed. For instance, on
small astronomical bodies with weak gravi-
tational attractions atmospheres cannot long
endure. Like the moon these bodies must
gradually lose nearly all their gases to space.
Such loss has almost certainly occurred from
the earth itself, and probably accounts for
the absence of hydrogen and helium from the
air. These gases, being very light, are not
attracted with sufficient force to the earth,
and gradually rise to the upper level of the
atmosphere and fly away. Again, in the ab-
sence of a near-by sun which steadily provides
energy to balance loss by radiation, the period
during which water and carbonic acid can
remain in an atmosphere must be relatively
short. Graduallv, but in a time whollv in-
considerable in comparison with the duration
of the terrestrial atmosphere, the gases sur-
rounding bodies so placed must condense and
then solidify. Finally, a body which con-
stantly turns one face to a sun must slowly
condense its whole atmosphere upon its dark,

THE ENVIRONMENT 59

cold surface, and so no less certainly be de-
prived of a gaseous envelope and of oceans.

Accordingly it appears safe to say that
really durable atmospheric conditions depend
upon sufficient size of the planet, the presence
of a sun, and rotation.1 No doubt a host of
other factors which exist in the case of the
earth are only less important. In any event,
all such phenomena, though varied by chance,
are of automatic origin, and whatever may be
the peculiarities of our solar system there is
no reason to suppose that like conditions
are not of frequent occurrence. Throughout
space there must be thousands of planets
which, like the earth and Mars, are enveloped
in an atmosphere that endures through count-
less centuries, and that contains great quan-
tities of water and carbon dioxide.

All such atmospheres must in greater or
less degree manifest general meteorological
phenomena. There must be winds and clouds,
rain and snow and ice, the formation of oceans
and ocean currents, streams and lakes, all in-
terrelated by complex cyclic processes which
endure. Tides, too, and magnetic and elec-
trical phenomena cannot be absent, while

1 A full discussion of all such problems will be found in the
"Lehrbuch" of Arrhenius and in S. Giinther's "Handbuch
der Geophysik." Two volumes, Stuttgart, 1897-1898.

60 THE FITNESS OF THE ENVIRONMENT

the action of water through long ages must
accomplish its gigantic work of disintegration
and sedimentation. Soil must be formed, and
water must penetrate it. In short a possible
abode of life not unlike the earth apparently
must be a frequent occurrence in space.

GENERAL COSMOGRAPHICAL CONCLUSIONS

Such, in the present state of knowledge,
are the general cosmographical views which
naturally suggest themselves to one who
considers the possibility of life throughout
the universe. The solar system appears to
be, in its most general traits, a fair sample
of the whole ; the sun is a typical star ; the
planets are certainly members of a large class
of similar bodies. These various types of
material aggregation are a good deal alike
wherever they occur. They are formed of
the same matter, probably in very much the
same proportions. They are actuated by the
same manifestations of the same energy, and
their evolutionary histories are similar. One
and all are likely to possess, for a longer or
shorter time, climates which make life possible.
On the other hand, it is already obvious that

THE ENVIRONMENT 61

the solar system, and especially the eartli
among planets, are very favorable for life,
partly through apparently accidental circum-
stances. Putting aside, therefore, the biological
fitness of the special climates of the earth both as
a familiar fact, and as possibly in no small de-
gree accidental, we may more advantageously
give our attention at once to other phenomena
which appear to be of a far more general
character, — the occurrence of large quanti-
ties of water and carbon dioxide in the atmos-
phere, and the fundamental meteorological
processes which their presence involves. Ni-
trogen and various other substances auto-
matically find a place beside water and car-
bonic acid, but it will be convenient to pass
them by or to postpone the consideration
until other aspects of the subject have been
more fully developed.

VI

THE PRIMARY CONSTITUENTS OF THE
ENVIRONMENT

Of course a consideration of the prop-
erties of water and carbonic acid might
be approached from a study of terrestrial
processes exclusively. But since the assump-
tion that such phenomena are common occur-

62 THE FITNESS OF THE ENVIRONMENT

rences throughout the universe, and that they
are the normal result of cosmic evolution, does
not in any way modify the subsequent course
of the inquiry, there appears to be no loss of
logical security from its introduction. Mean-
while the evidence that the special phenomena
under discussion are probably the nowise ex-
ceptional outcome of the operation of general
laws, and not merely sporadic, cannot fail to
lend weight to whatever conclusions may
ultimately be reached.

Obviously it is in the physical and chemical
attributes of these two compounds and their
constituent elements that we find very many
of the conditions which make life possible
upon the earth. They are material, provided
and mobilized automatically, out of which
living things undoubtedly can be formed.
Moreover if we limit our study to the physico-
chemical properties of water and carbonic
acid, and to the compounds of carbon, hydro-
gen, and oxygen, we shall greatly simplify our
problem. It cannot be denied that this re-
striction, no less than the earlier decision to
restrict the postulated characteristics of life
to complexity, regulation, and metabolism, is
sure to limit the inquiry, often perhaps in a
very unwelcome manner. On the other hand,
the gain in economy and security is once

THE ENVIRONMENT 63

more of great importance, and at present is
perhaps essential to clear thinking. Such a
procedure manifestly influences not at all the
validity of any conclusions which may be
reached ; only it must not be forgotten that
the conclusions apply directly to our limited
field of inquiry alone.

VII

THE ULTIMATE PROBLEM

Such is the outcome of a preliminary
glance at the many departments of science
which are necessarily involved in the ques-
tion of fitness of the environment. Living
things permit themselves to be simplified into
mechanisms which are complex, regulated,
and provided with a metabolism ; the environ-
ment, by a series of eliminations, is reduced
to water and carbonic acid. These are sim-
plifications counseled solely by expediency.
Neither logical process is necessary ; each in-
volves a disregard for many circumstances
which might be of weight in the present in-
quiry. But in the end there stands out a
perfectly simple problem which is undoubt-
edly soluble. That problem may be stated
as follows : In wrhat degree are the physical,
chemical, and general meteorological char-

64 THE FITNESS OF THE ENVIRONMENT

acteristics of water and carbon dioxide and
of the compounds of carbon, hydrogen, and
oxygen favorable to a mechanism which must
be physically, chemically, and physiologi-
cally complex, which must be itself well regu-
lated in a well-regulated environment, and
which must carry on an active exchange of
matter and energy with that environment?

The first step in seeking a solution must be
to review the data of physics and chemistry
which describe the properties of water and
carbonic acid, having due regard to their
meteorological significance. Such data of the
highest accuracy exist in great profusion, for
almost every conceivable property of these
substances has been studied with patient care.
Next, the properties of the compounds of
carbon, hydrogen, and oxygen must be con-
sidered, and some of the characteristics of
the chemical reactions into which they enter
must be discussed. For this examination the
unparalleled development of the science of
organic chemistry provides ample material.
All of these things must be scrutinized quan-
titatively as well as qualitatively, and here
again there is no lack of necessary information.

Immediately one advantage of the method
here proposed becomes evident. We can deal
with the familiar abstractions of physical

THE ENVIRONMENT 65

science, — specific heat, coefficient of expan-
sion, solubility, heat of reaction, etc., — and
thereby we shall gain all the advantages of
the most exact sciences. No qualifications,
no doubtful or contentious matter, no imper-
fect descriptions need enter.

In this manner it will be easy to estimate
the absolute biological fitness in certain re-
spects of water and carbonic acid, and at once
a host of automatic results of their proper-
ties will become evident. Many of these re-
sults, such as the nearly constant temperature
of the ocean, the ample rainfall, the freezing
of water upon the surface, the great variety of
carbon compounds, are familiar subjects of
speculation, though since Darwin little in-
terest has been manifested in them ; others,
only recently brought to light by the growth
of physical science, are nearly or quite un-
known in this connection. All deserve to
receive more serious attention from biologists
than is at present vouchsafed them, for they
constitute a part of the very foundation of
general biology, and they cause many of the
phenomena with which man is concerned in
his struggle for mastery of the environment.

Yet the mere exposition of such facts and
relationships cannot suffice in a discussion of
the fitness of the environment. In the first
p

66 THE FITNESS OF THE ENVIRONMENT

place these are in the main familiar ideas,
and if they were altogether conclusive to
prove the existence of really significant fitness,
if they could be regarded as alone adequate
to establish the necessity of putting fitness by
the side of adaptation as a coordinate factor
in causing the marvels of life, it is hard to be-
lieve that they would have been so long neg-
lected. In the second place there is nothing
comparative about such information. Water
is indeed a wonderful substance which fills
its place in nature most satisfactorily, but
would not another substance do as well ? Is
not ammonia, for example, a possible substi-
tute ? And are there not many other chemical
bodies which might, in a very different world,
serve equally useful purposes ? Perhaps, too,
the great variety of carbon compounds which
are known to the chemist are known only be-
cause the vital processes furnish an abundance
of material with which to experiment. Is it
not possible, therefore, that another element,
silicon, for instance, may enter into even
greater varieties of compounds ? It is such
questions, ever present in the minds of men of
science, yet never carefully scrutinized to see
if an answer be possible, which, I suspect, have
long deflected attention from this subject.
Clearly, therefore, it will be necessary to

THE ENVIRONMENT 67

compare the proper! ios of water and carbonic
acid and of the carbon compounds with those of
other substances. It will be necessary to find
out whether these substances are not only fit
but fittest, — and this no doubt is a task of a
very different sort. It may even seem at first
sight an impossible one, but I hope to show
that this is not the case, and that in spite
of the incompleteness of our physical and
chemical knowledge, it may be pressed to a
satisfactory issue. A few remarks may now
indicate the general line of thought we shall
pursue, and then the actual study must pro-
vide the proof.

VIII

THE METHOD OF SOLUTION

The very constant temperature of the ocean
is a most important factor in the economy of
nature. It constitutes, for example, a vital
regulation of the environment of a large pro-
portion of all the living organisms of the world,
and it has many other important "functions.'
This constancy of temperature is in large part
due to the magnitude of the specific heat of
water. Other things being equal, the greater
the specific heat of water, the more constant
must be the temperature of the ocean. If,

68 THE FITNESS OF THE ENVIRONMENT

then, the specific heat of water, as is actually
the case, be nearly or quite a maximum among
all specific heats, it follows that the fitness of
water in this respect is nearly maximal.

Again the ocean contains an astonishing
variety of substances in solution, and they
are present often in large quantities. In this
manner a very great supply of food in very
great variety is offered marine organisms.
Of course such richness of the environment is
an exceedinglv favorable circumstance for the
organism, and it is due principally to the
ability of water to dissolve a multitude of
things in large quantities. It is not to be
supposed that the substances present in sea
water are all of use to every organism. This
need not be the case at all ; but a variety of
supplies which may be adapted to special re-
quirements as they arise, here iodine, there cop-
per, for instance, is a very genuine advantage.
Further, the vast utility of the solvent action
of water in blood, lymph, and all the body
fluids is too patent to call for comment. If,
now, it can be shown that the efficiency of
water is nearly or quite a maximum, as it
really is, among all known solvents, then it
must be evident that in another respect the
fitness of water is nearly or quite maximal.

Again the amount of energy that is re-

THE ENVIRONMENT 69

quired to tear apart molecules of water, and
to liberate hydrogen and oxygen, is very great
indeed, and when hydrogen and oxygen re-
combine to form water, this energy must
reappear, — under ordinary circumstances as
heat. This fact, too, is very favorable for the
organism, because almost all compounds which
contain hydrogen yield a great deal of energy
when they are burned ; they are, in short, great
reservoirs of energy which can be tapped in
the process of metabolism. If, therefore, the
heat of combustion of hydrogen be nearly or
quite a maximum, as it is, among all sub-
stances, it is clear that water is again, in an-
other respect, most wonderfully fitted for life.

Finally, if it be true, and such is the case,
that very few of the substances which share
the fitness of water in one of these character-
istics also share or approach its fitness in
either of the others, and that none possesses
all these qualifications in a degree that merits
consideration, it must, I conceive, be admitted
that so far as the investigation has proceeded
water is the only possible fit substance.

A criticism may here be made ; are there
not other substances which possess other
groups of qualifications which water lacks ?
And that is a difficulty which is even harder
to meet. But in the first place it is evident

70 THE FITNESS OF THE ENVIRONMENT

that there are not an infinity of important
physical properties ; in fact there are very
few. And in the second place it is evident,
both from centuries of experience in physical
science and from the postulates above adopted
regarding life, which undoubtedly do in the
main describe its physico-chemical character-
istics, that very few properties indeed are of
importance in the least comparable with those
which I have mentioned.

Finally, it is in the highest degree probable
that we are acquainted with most of the truly
essential physical properties, and know them as
biologically important, when they are so ; and I
think we shall find it possible to consider them
all, and thus to make the argument complete.

Meanwhile it should be noted that there are
two different ways of illustrating the fitness
of a physical property. Properly employed,
both are free from fallacy, and it will be de-
sirable for us to employ both. Thus it may
be shown, as in the case of the temperature of
the ocean, that a particular property of water,
its high specific heat, automatically produces
a maximum of something which is favorable
to life. Or again, as in the case of the regula-
tion of the temperature of the human body by
the process of perspiration, it may be shown
that a particular property of water, its high

THE ENVIRONMENT 71

heat of vaporization, has been utilized through
adaptation of the organism to secure very
high efficiency in a physiological process.

Such is the method which must be followed
in order to decide the question of the fitness of
the environment. The physico-chemical char-
acteristics of water, carbonic acid, and the
carbon compounds are to be taken up one by
one, and their absolute and relative magnitudes
considered. The possible utility of such proper-
ties, both automatically and through process of
organic adaptation, must then be estimated,
bearing in mind the fundamental characteris-
tics of the living organism which have been
arbitrarily postulated. Finally the various
favorable qualities of water, carbonic acid,
and the carbon compounds must be grouped
together in order to see if they constitute a
unique ensemble of fitness, among all possible
chemical substances, for a living organism
which must be complex, regulated, and en-
gaged in active metabolism.

At length the problem of fitness appears in
a simple form. The road to a solution is
open, and we may now proceed to an untram-
meled discussion of unexceptionable data and
well-known laws of physics, chemistry, meteor-
ology, and physiology. Without further hypo-
thetical difficulties, these must lead to the goal.

CHAPTER III
WATER

GENERAL CONSIDERATIONS

IT was assuredly not chance that led Thales
to found philosophy and science with the
assertion that water is the origin of all things.
Whether his belief was most influenced by
the wetness of animal tissues and fluids, or by
early poetic cosmogonies, or by the ever pres-
ent importance of the sea to the Ionians,1
however vague his conception of water may,
indeed must, have been, he at least expressed
a conclusion which proceeded from experience
and serious reflection. Later, when positive
knowledge had already grown to be a sub-
stantial basis for speculation, both meteor-
ological and chemical views contributed to
the decision of Empedocles and Aristotle to
include water among the elements.2 And it
is especially worthy of note that of earth, air,

1 Windelband, "Ilandbuck der Altertumswissenschaft,"
V. 1. 139. Nordlingen, 1888.

2 Windelband, I.e.; S. Giintlier, " Geschichte der Natur-
wissenschaften." Reclam, Leipzig, Vol. I, p. 19.

72

WATER 7 ;

fire, and water the last is the only one which
happens to be an individual chemical com-
pound. From that day to this the unique
position of water has never been shaken. It
remains the most familiar and the most im-
portant of all things.

Within a comparatively recent time, to be
sure, it has definitely lost its claim to be a true
element, in the modern sense, but meanwhile
almost every great development of science has
but contributed to make its importance more
clear. In physics, in chemistry, in geology,
in meteorology, and in biology nothing else
threatens its preeminence. The physicist has
perforce chosen it to define his standards of
density, of heat capacity, etc., and as a means
to obtain fixed points in thermometry. The
chemist has often been almost exclusively
concerned with reactions which take place in
aqueous solution, and the unique chemical
properties of water are of fundamental sig-
nificance in most of the departments of his
science. In geology neptunism has at length
won a certain though incomplete truimph over
plutonism, and the action of water now appears
to be far the most momentous factor in geolog-
ical evolution.1 The meteorologist perceives

1 "Of all geological agencies water is the most obvious and
apparently the greatest, though its efficiency is conditioned

74 THE FITNESS OF THE ENVIRONMENT

that the incomparable mobility of water,
which depends upon its peculiar physical prop-
erties and upon its existence in vast quanti-
ties in all three states of solid, liquid, and
gas, is the chief factor among the properties of
matter to determine the nature of the phenom-

upon the presence of the atmosphere, upon the relief of the
land, and upon the radiant energy of the sun. Through the
agency of rainfall, of surface streams, of underground waters,
and of wave action, the hydrosphere is constantly modifying
the surface of the lithosphere, while at the same time it is
bearing into the various basins the wash of the land and
depositing it in stratified beds. It thereby becomes the
great agency for the degradation of the land and the building
up of the basin bottoms. It works upon the land partly by
dissolving soluble portions of the rock substance, and partly
by mechanical action. The solution of the soluble part usu-
ally loosens the insoluble, and renders it an easy prey of the
surface waters. These transport the loosened material to
the valleys and at length to the great basins, meanwhile roll-
ing and grinding it and thus reducing it to rounder forms and a
finer state, until at length it reaches the still waters or the low
gradients of the basins and comes to rest. The hydrosphere
is, therefore, both destructive and constructive in its action.
As the beds of sediment which it lays down follow one another
in orderly succession, each later one lying above each earlier
one, they form a time record. And as relics of the life of
each age become more or less imbedded in these sediments,
they furnish the means of following the history of life from
age to age. The historical record of geology is, therefore, very
largely dependent upon the fact that the waters have thus
buried in systematic order the successive life of the ages."
— Chamberlin and Salisbury, "Geology." New York,
1904, Vol. I, p. 8.

WATER 75

ena which he studies;1 and the physiologist
has found that water is invariably the prin-

14'0f all the terrestrial agents by which the surface of
the earth is geologically modified, by far the most important
is water. We have already seen, when following livpogene
changes, how large a share is taken by water in the phenom-
ena of volcanoes and in other subterranean processes. Re-
turning to the surface of the earth and watching the opera-
tions of the atmosphere, we soon learn how important a part
of these is sustained by the aqueous vapor that pervades
the atmosphere.

"The substance which we term water exists on the earth
in three well-known forms: (1) gaseous, as invisible vapor;
(2) liquid, as water; and (3) solid, as ice. The gaseous
form has already been noticed as one of the characteristic
ingredients of the atmosphere. Vast quantities of vapor
are continually rising from the surface of the seas, rivers,
lakes, snow fields, and glaciers of the world. This vapor
remains invisible until the air containing it is cooled down
below its dewpoint, or point of saturation, — a result which
follows upon the union or collision of two aerial currents of
different temperatures, or the rise of the air into the upper
cold regions of the atmosphere, where it is chilled by expansion,
by radiation, or by contact with cold mountains. Condensa-
tion appears only to take place on free surfaces, and the
formation of cloud and mist is explained by condensation
upon the fine microscopic dust of which the atmosphere is
full. At first minute particles of water vapor appear, which
either remain in the liquid condition, or, if the temperature
is sufficiently low, are frozen into ice. As these changes take
place over considerable spaces of the sky, they give rise to
the phenomena of clouds. Further condensation augments
the size of the cloud particles, and at last they fall to the sur-
face of the earth, if still liquid, as rain ; if solid, as snow or
hail; if partly solid and partly liquid, as sleet. As the
vapor is largely raised from the ocean surface, so iu great

76 THE FITNESS OF THE ENVIRONMENT

cipal constituent of active living organisms.1 '
Water is ingested in greater amounts than all

measure it falls back again directly into the ocean. A con-
siderable proportion, however, descends upon the land, and
it is this part of the condensed vapor which we have now
to follow. Upon the higher elevations it falls as snow, and
gathers there into snow fields, which, by means of glaciers,
send their drainage towards the valleys and plains. Else-
where it falls chiefly as rain, some of which sinks underground
to gush forth again in springs, while the rest pours down the
slopes of the land, swelling the brooks and torrents which,
fed both by springs and rains, gather into broader and yet
broader rivers that bear the accumulated drainage of the
land out to sea. Thence once more the vapor rises, con-
densing into clouds and rain to feed the innumerable water
channels by which the land is furrowed from mountain top
to seashore.

"In this vast system of circulation, ceaselessly renewed,
there is not a drop of water that is not busy with its allotted
task of changing the face of the earth. When the vapor
ascends into the air, it is, comparatively speaking, chemi-
cally pure. But when, after being condensed into visible
form, and working its way over or under the surface of the
land, it once more enters the sea, it is no longer pure, but more
or less loaded with material taken by it out of the air, rocks,
or soils through which it has traveled. Day by day the
process is advancing. So far as we can tell, it has never ceased
since the first shower of rain fell upon the earth. We may
well believe, therefore, that it must have worked marvels
upon the surface of our planet in past time, and that it may
effect transformation in the future." — Geikie, "Textbook
of Geology." London, 1903, 4th ed., Vol. I, pp. 447, 448.

1 Thus water makes up from 70 to 85 per cent of fishes,
about 87 per cent of oysters, 85 per cent of apples, 78 per
cent of potatoes, 95 per cent of the edible portion of lettuce,
etc.

WATER 77

other substances combined, and it is no less
the chief excretion. It is the vehicle of the
principal foods and excretory products, for
most of these are dissolved as they enter or
leave the body.1 Indeed, as clearer ideas of
the physico-chemical organization of proto-
plasm have developed it has become evident
that the organism itself is essentially an
aqueous solution in which are spread out col-
loidal substances of vast complexity.2 As a
result of these conditions there is hardly a
physiological process in which water is not of
fundamental importance.

All of these circumstances, which completely
justify the interest in water which Thales and
Aristotle, and nearly all later students of nature
have manifested, depend in great part upon
the quantity of water which is present out-
side the earth's crust, and upon its often
unique physical and chemical properties.

1 Properly speaking, the entrance of the foods into the
body is across the wall of the intestine; at this point the
foods have all undergone digestion and are almost exclu-
sively in solution. In like manner excretion takes place
across the renal epithelium, or the epithelium of the lungs,
or across that of the sweat glands; these too are traversed
only by substances in solution.

2 "Der Organismus, Pflanze wie Tier, ist ein Geftss voll
wasseriger Losung, in dem sich als disperse Phase verschieden-
artige Kolloide befinden." — Bechhold, "Die Kolloide in
Biologie und Medizin." Dresden, 1912.

78 THE FITNESS OF THE ENVIRONMENT

Such properties are our present concern.
Doubtless if it were not for the enormous
quantity of water which exists upon our
planet, all its physical properties would be of
little avail to bring about its universal im-
portance in nature. This, however, as has
been above explained, appears to be neither
an accidental nor an uncommon phenomenon.
Of the total extent of the earth's surface
the oceans make up about three fourths, and
they contain an amount of water sufficient,
if the earth were a perfect sphere, to cover
the whole area to a depth of between two and
three miles. This corresponds to about 0.2 per
cent of the volume of the globe. The occur-
rence of water is, moreover, not less important
and hardly less general upon the land. In
addition to lakes and streams, water is al-
most everywhere present in large quantities in
the soil, retained there mainly by capillary
action, and often at greater depths. The
atmosphere also contains an abundance of
water as aqueous vapor and as clouds. Now i
the very occurrence of water upon the earth,
and especially its permanent presence, is due
in no small degree to its chemical stability
in the existing physical and chemical con-
ditions. This stability is of great moment in
the various inorganic and organic processes

WATER 79

in which water plays so large a part. In the
first place the chemical reactions in which it
is concerned during the process of geological
evolution, though they are no doubt in the
total of great magnitude, are both slow and
far from violent. Long since any very active
changes of this sort, so far as the superficial
part of the crust is concerned, have run their
course. In the second place water is really,
at the temperature of the earth and in com-
parison with most other chemical substances,
an extremely inert body, for the union of hydro-
gen with oxygen is so firm that it is not readily
dissolved.

Thus water exists as a singularly inert con-
stituent of the atmosphere, as a liquid nearly
inactive in chemical processes on the surface
and in the soil, and everywhere as a mild sol-
vent which does not easily attack the sub-
stances which in great variety dissolve in it.
The chemical changes which do follow upon
solution are not such as to produce substan-
tial chemical transformations, and most sub-
stances can pass through water unscathed.
The nature of water, then, is a great factor in
the chemical stability, which, no less than the
physical stability of the environment, is es-
sential to the living mechanism. But it may
be questioned if such stability would not

80 THE FITNESS OF THE ENVIRONMENT

necessarily be ultimately attained in greater or
less degree with almost any other substance,
as a result of the general tendency of chemical
processes to reach a condition of equilibrium,
and it will therefore be well to turn to more
secure fields of inquiry.

THERMAL PROPERTIES

The most familiar among such are certain
characteristics of water which have been long
known, and which, as the Bridgewater Trea-
tises and other works on natural theology
testify, were formerly favorite subjects of
metaphysical speculation, — the thermal prop-
erties. These characteristics of water were
recognized at an early stage in the develop-
ment of modern science, and in many cases
their special importance in meteorology and
in other departments of the sciences of nature
is almost self-evident.

A

SPECIFIC HEAT

First among these is the heat capacity or,
as it is more commonly termed, the specific
heat of water. This quantity has the value of

WATER 81

1.000 for the interval between 0° and 1°
centigrade, a number which is due to the
choice of water in defining the calorie or
fundamental unit of heat. The caloric, small
calorie, or gram calorie is that quantity of
heat which is required to raise the temperature
of one gram of water through 1° centigrade,
and it varies slightly with the temperature,
having the relative values 1.000 for the in-
terval from 0° to 1°, 0.998 for the interval from
4° to 5°, 0.992 for the interval from 15° to
16°, and its mean value for the interval from
0° to 100° is 1.004. The heat capacity of ^
water is then 1.000, in that 1.000 calorie is re-
quired to raise the temperature of 1.000 gram
of water through 1.000 degree centigrade.

The approximate specific heats of a variety
of important substances are as follows: —

[liquid .... 1.00
Water I solid . . . .0.50

[gas .... 0.3-0.5

Lead 0.03

Iron 0.10

Quartz 0.19

Salt 0.21

Marble 0.22

Glass 0.20

Sugar 0.30

Ammonia, liquid . . .1.23

Chloroform O.ii

Hydrogen 3.4

Alcohol 0.5-0.7

Hexane 0.50

It is unnecessary to enter upon an elaborate
analysis of the data concerning specific heats,
for the magnitude of the specific heat of a
substance is dependent upon its chemical
nature, as was first made clear b}T Dulong

82 THE FITNESS OF THE ENVIRONMENT

and Petit in 1819. The law which bears their
name consists of the statement that in the
case of elementary substances the product of
specific heat and atomic weight is a constant,
— roughly, 6.4. Certainly this so-called law
is a mere approximation, and some elements,
notably carbon, silicon, and boron, at the
ordinary temperature, depart widely from its
requirements, but in the main the approxi-
mation holds good. Later the researches of
Neumann, Gamier, Cannizaro, and especially
of Kopp made possible an extension of the law
to compounds.

It is evident that the law of Dulong and
Petit amounts to the statement that for all
elementary substances the quantity of heat
which is required to change the temperature
of every atom, regardless of its nature, is a
constant. A brief discussion will serve to
make this plain. According to the law the
specific heat of an element varies inversely
as its atomic weight, diminishing as the atomic
weight increases, so that the product of the
two quantities remains constant. But of
course the number of atoms per gram of sub-
stance also varies inversely as the atomic
weight. Hence the specific heats of elemen-
tary substances and the number of atoms per
gram are always roughly proportional, which

WATER

83

can only be the case if all atoms, no matter
of what element, require a constant amount of
heat to raise their temperatures one degree.
That is to say, in all elementary substances
the heat capacity of the atom is constant, and
independent of the nature of the element
(with the qualifications above noted).

The study of compounds has shown that
this same generalization is also true of them.
This means that in all substances the heat
capacity of every atom is nearly constant and
is independent of its nature and of that of the
compound in which it finds itself.

Accordingly the law of Dulong and Petit
may be formulated as follows ; — the specific
heat of a substance multiplied by the average
of the atomic weights of all the constitutent
atoms in the molecule is often equal to about
6.4, and is always not very different from this
number. This conclusion may be tested with
the data above recorded.

Substance

Molecular
Weight

Number

of
Atoms

Average
Atomic
Weight

Sfbczfio

1 Ii:at

Specific Heat

X

Atomic Weight

Water
Ammonia
Quartz .
Salt . .
Sugar . .
Hexane .

18
17
60
58
342
86

3
4
3
2
45
20

6
4
20
29
8
4

1.0
1.2
0.2
0.2
0.3
0.5

6.0
4.8
4.0
5.8
2.4
2.0

84 THE FITNESS OF THE ENVIRONMENT

It must be confessed that such data are not
a brilliant confirmation of the law. A series
of numbers which vary from 2.0 to 6.0 is
something quite different from constancy,
and every one of these numbers is less than
6.4. It is, however, certain that these quanti-
ties are uniformly of the same order of magni-
tude, and this is all that is of importance for
our present purpose. For accordingly they
prove that unless the average atomic weight
of a substance be very low its specific heat
cannot be very high. Of course only com-
pounds which are largely made up of hydrogen
can possess very low average atomic weights,
and among such those will be lowest in this
respect which contain a relatively small number
of atoms of another element of low atomic
weight, like carbon, nitrogen, oxygen, etc.
Of such substances the hydrocarbons make up
the only numerous group, and for the most
part their specific heats appear to be, like
that of elementary carbon itself, considerably
lower even than would be predicted by the
rule. So it is that the conclusion is warranted
that water shares the characteristic of very
high specific heat with a very small number of
substances, among which hydrogen and am-
monia are probably the only important chemi-
cal individuals. From this conclusion another

WATER 85

follows directly; namely, that water possesses
certain nearly unique qualifications which
are largely responsible for making the earth
habitable, or at least very favorable as a
habitation for living organisms.

It need hardly be pointed out that this
importance of the high heat capacity of water
is a very well-known fact. Even in the early
decades of the nineteenth century, when
natural theology and argument from design
were the subject of lively controversy, es-
pecially in England, such subjects were very
familiar, and an excellent temperate dis-
cussion from the theologian's side will be found
in Whewell's Bridgewater Treatise.1 At that
time, before a clear formulation of the concept
of adaptation existed, it was of course impos-
sible to disentangle such natural fitness from
the results of the organic evolutionary process.
In the more modern period since the publi-
cation of "The Origin of Species," the late
Professor J. P. Cooke of Harvard has dwelt
upon this and other properties of water
and sought to show that, lying wholly apart
from the new ideas, such phenomena remain

1 Chapter IX of this work deals with "The Laws of Heat
with Respect to Water." Although the ideas are somewhat
vague, the importance of the capacity of water to absorb
heat is clearly brought out.

86 THE FITNESS OF THE ENVIRONMENT

unexplained and inexplicable by our present
laws of natural science. He, too, endeavored
to employ such facts as theological arguments
but, in spite of many sound contentions, with
less success in a more skeptical age.1

The most obvious effect of the high specific
heat of water is the tendency of the ocean and
of all/lakes and streams to maintain a nearly
constant temperature. This phenomenon is
of course not due to the high specific heat
of water alone, being also dependent upon
evaporation, freezing, and a variety of cir-
cumstances which automatically mix and stir
water. But in the long run the effect of
high specific heat is of primary importance.
It will be convenient to postpone considera-
tion of the regulation and importance of the
constant temperature of the ocean until the
other properties of water which contribute
thereto have been discussed.

A second effect of the high specific heat of

1 "Assume that the variations preserved by natural selec-
tion are all accidental, a point on which naturalists greatly
differ, still what is the result ? An adaptation to the environ-
ment. According to the theory, then, the conditions of the
environment are a determining cause ; and unless we believe
that all nature was the result of a fortuitous concourse of atoms,
we can find in these conditions abundant opportunities where
intelligent causation can act." — Josiah Parsons Cooke,
"The Credentials of Science." New York, 1888, p. 251.

WATER

87

water is the moderation of both summer and
winter temperatures of the earth. It is not
easy to estimate the total magnitude of this
effect, but the manner in which it comes about
is well illustrated by the differences between
seaboard and inland climates or between the
climate of a large part of the United States,
which is a continental climate, and that of
Western Europe, which is essentially an in-
sular climate. In the most extreme form
such moderation of climate is to be observed
on the high seas and upon small islands.
There are found the smallest known differences
between the mean temperatures of different
months of the year and of different hours of
the day, and the least tendency to violent
changes of temperature. The calculation of
Zenker regarding normal temperatures may

Latitude

Continental Climate

Marine Climate

Difference

Degrees

Degrees

Degrees

Degrees

0

34.6

26.1

-8.5

10

33.5

25.3

-8.2

20

30.0

22.7

-7.3

30

24.1

18.8

-5.3

40

15.7

13.4

-2.3

50

5.0

7.1

2.1

60

-7.7

0.3

8.0

70

-19.0

-5.2

13.8

80

-24.9

-8.2

16.7

90

-26.1

*

-8.7

17.4

88 THE FITNESS OF THE ENVIRONMENT

be cited as a good illustration of the nature of

the case.1

It is unnecessary to discuss the effects
upon living organisms of the equable tem-
perature of the ocean and of the moderation
of climate, for obviously we are here confronted
by a true instance of regulation of the environ-
ment.

The high heat capacity of water operates
in still another manner to regulate tempera-
ture upon the land and at the same time to
increase the mobility of the environment of
marine organisms. For directly or indirectly
it is involved in the formation and duration
of ocean currents, especially the movement of
water in the depths from the polar to the
tropical seas, and it determines the amount
of heat carried by such currents. A similar
and even more important "function' is the
direct promotion of winds, with the resulting
distribution of aqueous vapor throughout the
atmosphere, a primary factor in the dissemina-
tion of water by means of the rainfall. Here
the essential thing is the existence of a vast
warm reservoir in the tropics and of two
similar cold reservoirs at the poles. Under

1 A discussion of Zenker's work will be found in Hanns
"Handbook of Climatology," translated by Ward, pp. 210-
215.

WATER 89

these circumstances the circulation of winds,
bearing away water vapor from the tropical
oceans, is inevitable, and the process is
intensified by the high specific heat of
water.

The living organism itself is directly favored
by this same property of its principal constit-
uent, because a given quantity of heat pro-
duces as little change as possible in the tem-
perature of its body. Man is an excellent
case in point. An adult weighing 75 kilo-
grams (165 pounds) when at rest produces
daily about 2400 great calories, which is an
amount of heat actually sufficient to raise
the temperature of his body more than 32°
centigrade. But if the heat capacity of his
body corresponded to that of most substances,
the same quantity of heat wTould be sufficient
to raise his temperature between 100° and
150°. In these conditions the elimination of
heat would become a matter of far greater
difficulty, and the accurate regulation of the
temperature of the interior portion of his body,
especially during periods of great muscular
activity, well-nigh impossible. Extreme con-
stancy of the body temperature is, of course,
a matter of vital importance, at least for all
highly organized beings, and il is hardly
conceivable that it should be otherwise. In

90 THE FITNESS OF THE ENVIRONMENT

the first place marked influence of change of
temperature upon chemical reaction is almost
universal, and as a rule an increase of 10°
centigrade in temperature will more than
double the rate of a chemical change.1 Sec-
ondly all living organisms contain both chemi-
cal substances and physico-chemical struc-
tures or systems which begin to be altered,
and usually irreversibly altered, at a tempera-
ture which is very little above that of the
human body.2 It is perhaps imaginable that

1 If the velocity of a chemical reaction be represented by
a coefficient, k, the increase in its magnitude with rising tem-
perature is unlike that of ordinary physical coefficients, and
in many cases amounts to a two or threefold rise for a tem-
perature increase of 10° centigrade. The well-known data
concerning the transformation of dibromsuccinnic acid into
brommaleic acid and hydrobromic acid in aqueous solution
illustrate a typical case.

t

k

15°

0.00000967

40°

0.0000863

50°

0.000249

60.2°

0.000654

70.1°

0.00169

80°

0.0046

89.4°

0.0156

101°

0.0318

2 This is attested not only by the low temperature at
which many proteins coagulate, but also by the action of
temperatures between 50° and 60° to inactivate enzymes, and

WATER 91

conditions might be otherwise in beings of a
very different kind, but to-day every chemist
well knows that if he is to control a chemical
process, almost the first desideratum is rigid
regulation of the temperature at which the
process takes place.1

It is therefore incontestable that the un-
usually high specific heat of water tends
automatically and in most marked degree to
regulate the temperature of the whole envi-
ronment, of both air and water, land and sea,
and that of the living organism itself. Like-
wise the same property favors the circulation
of water by facilitating the production of
winds, besides contributing to the formation
of ocean currents. Here is a striking instance
of natural fitness, which in like degree is un-
attainable with any other substance except
ammonia.

to produce alterations in many of the complex substances
that are involved in the phenomena of immunity and other
similar things.

1 Almost the most conspicuous change in the equipment
of modern chemical laboratories, as a result of the growth of
physical chemistry, is the introduction everywhere of thermo-
stats.

92 THE FITNESS OF THE ENVIRONMENT

B

LATENT HEAT

Very different from specific heat in their
relationship to the chemical constitution of
a substance, but not unlike it in biological
importance, are the so-called latent heats of
melting and of evaporation.

The latent heat of melting is expressed as
the number of calories which are required to
convert one gram of solid at the freezing point
into one gram of liquid at the same tempera-
ture. For water its value is approximately
80, which indicates that the same quantity
of heat must be employed to melt ice as to
raise the temperature of the resulting ice-
water to 80° centigrade.

The latent heat of evaporation is similarly
defined as the number of calories required to
change one gram of liquid into vapor. Its
magnitude depends upon the temperature at
which the process takes place. The latent
heat of evaporation of water is approximately
536. There is required, accordingly, as much
heat to boil away one gram of water as to
raise the temperature of 536 grams through 1°
centigrade.

There are a number of important effects of

WATER 93

the high latent heals of fusion and evapora-
tion of water upon the meteorological pro-
cesses. When, for example, a body of water
becomes cooled to its freezing point, the
further abstraction of heal cannol lower il>
temperature below that point, which, to be
sure, is somewdiat variable in the case of sail
water. And so long as water and ice exi>t
in contact, the system constitutes a ther-
mostat, a very accurate one if the water be
fresh, which changes only in respect to the
quantities of ice and water as heat is added or
removed.1 Heating serves merely to melt
the ice, cooling to freeze the water. Accord-
ingly, as long as the earth shall remain habit-
able the cooling of its oceans and seas will
remain rigidly limited by their freezing point.
However inclement the atmosphere, the ocean
can always support life until the final extinc-
tion of water by cold. It is worthy of note
that the freezing point of water, though to
man with his carefully regulated body tem-
perature apparently low, is in reality very
high indeed compared with that of any like
substances, — perhaps 100° centigrade above
the average.

1 In fact, there is no better means of obtaining a constant
temperature in the chemical laboratory than by mixing pure
ice with pure water.

94 THE FITNESS OF THE ENVIRONMENT

Table of Melting Points

Water

Hydride of antimony .
Hydride of arsenic . ,
Hydrobromic acid . ,
Hydrochloric acid
Hydrofluoric acid . ,
Hydriodic acid . . ,

Methane

Carbon dioxide . . ,
Hydride of phosphorus
Hydrogen sulphide . ,
Sulphurous oxide . . ,
Ammonia ....
Nitric oxide . . .

Degrees

H20

0

SWI3

-91.5

AsH3

-113.5

HBr

-87

HC1

-112.5

HF

-92.3

HI

-50

CKU

-185.8

C02

- 57

PH3

-132.5

H2S

-85.6

S02

-72.7

NH3

-75

NO

-167

This is, no doubt, one of the most important
facts with which we are concerned, for while a
very large number of chemical processes take
place quite freely at 0°, the conditions are
very different at the freezing point of am-
monia, for instance. At that temperature the
velocity of most chemical processes is but a
fraction of one per cent of their velocity at
0°, and a large part of the chemical activity
which is familiar to us ceases.

The result of the unusually high freezing
point of water and of the phenomenon of
latent heat is felt, however, not merely in the
avoidance of an excessive fall in the tempera-
ture of lakes and seas. As above explained,

WATER

95

whenever the ocean comes in contact with
climates of very low temperature it tends to
moderate them, the more effectively the
greater the disparity between the temperature
of the air and that of the water, and here
latent heat is quite as important a factor,
though indirectly, as specific heat.

It remains to point out that the latent heat
of melting of water is nearly the greatest
which has yet been discovered, being ex-
ceeded, in fact, by that of ammonia alone.

Table of Latent Heats of Melting

Substance

Formula

Melting
Point

Latent Heat
of Fusion

Pb

326°

5.4 Calories

Br

-7.3

16.2

Cd

321

13.7

Iron

Fe

23-33

Ga

13

19.1

I

11.7

K

58

15.7

Cu

Na

96.5

43
31.7

Ni

464

Pd

36.3

Phosphorus ....

P

Pt

27.35
1779

4.7
27.18

Hg

S
Ag

115

999

2.82

9.37

21.07

Bi

266.8

12.64

Zn

415

28.13

Tin !

Sn

233

14.25

96 THE FITNESS OF THE ENVIRONMENT

Melting

Latent Heat

Substance

Formula

Point

of Fusion

Water

H20

0°

80 Calories

Ammonia ....

NH3

-75

108

Antimony chloride .

SbCla

73

13.4

Antimony bromide .

SbBr3

94

9.7

Lead chloride . .

PbCU

485

20.9

Calcium chloride .

CaCl2-6H20

28.5

40.7

Potassium nitrate .

KX03

339

47.4

Sodium nitrate . .

NaNOj

310.5

63

Phosphoric acid

H3PO4

18

25.7

Nitric acid . . .

HNO3

-47°

9.5

Sulphuric acid . .

H2S04

10.3

24.

Sulphuric oxide . .

S03

76.7

Ethylene bromide .

C2H4Br2

8

13

Formic acid . . .

H.COOH

-7.5

57.4

Chloral hydrate

C2H3Cls02

46

33.2

Dimethyl oxalate .

C204(CH3)2

49.5

42.6

Acetic acid . . .

CH3COOH

43.7

Glycerine ....

C3H8U3

13

42.5

Stearic acid .

Ci8Hr,602

64

47.6

Benzene ....

CeHe

5.3

30.1

Nitrobenzene . .

C6H5N02

-9.21

22.3

Di-chlorbenzene

CeH4Cl2

52.5

29.9

p-Toluidine . . .

C7H9N

35.8

Phenol . . . .

C6H5OH

25.4

24.9

Menthol . . . .

CioII2oO

42

18.9

Phenylhydrazine .

CH6.NH.NHa

24.5

Phenylacetic acid .

C6H5.CH2.COOH

75

25.4

Naphthaline . . .

CioHg

80

35.7

Accordingly, the processes above described
possess nearly the highest possible efficiency.
A very large amount of heat must be ab-
stracted from a body of water before it can
be solidified; after a given amount of cool-

WATER 97

ing a very large quantity of water must re-
main liquid ; a body of water at 0° centi-
grade can warm up a very large amount of
colder air with the formation of a very small
quantity of ice. Thus the permanency of
the ocean, and the moderating effect of water
upon cold climates are very nearly maximal.
These are also facts, directly dependent upon
the physico-chemical nature of water, which
are remarkably favorable to the organism.

Still more important is the latent heat of
evaporation of water. Wherever water is
in contact with the air, evaporation must take
place until, if the system be of small dimen-
sions, equilibrium is established between aque-
ous vapor and the liquid; in short until the
air is saturated with water. Unlike freezing,
which occurs only at one particular tempera-
ture, this process goes on continuously through-
out all ranges of temperature at which liquid
water can exist, and even upon ice at low tem-
peratures. It is always accompanied by the
conversion of heat, in the' amount measured
by the latent heat of evaporation, into other
forms of energy ; the heat becomes latent.
And since air in contact with water is rarely
saturated with aqueous vapor, owing to the
constant movement of the atmosphere, the
process of evaporation, with the accompany-

98 THE FITNESS OF THE ENVIRONMENT

ing conversion of heat into latent heat, is a
continuous process. The phenomenon is a
variable one, however, for while at high tem-
perature, both because of the greater supply
of heat and because of the greater amount of
water vapor that the air can hold, the process
is very important and active, at low tem-
perature it is far less considerable. This in
itself is no doubt a benefit because it tends
especially to restrict the upward march of
temperature when the temperature is high,
but is of minor importance when the tempera-
ture is low.

In view of the other favorable qualities of
water it is perhaps not surprising to find that
its latent heat of evaporation is by far the
highest known. So great, in truth, is this
quantity and so important the process that
the latent heat of evaporation is one of the
most important regulatory factors at present
known to meteorologists.

When the sun shines upon a body of water,
only a small part of the energy which the
water receives contributes to the elevation of
its temperature. Thus Fitzgerald has con-
cluded from his studies of Lough Derg in
Ireland during clear hot summer weather l

1 See Hann, "Handbook of Climatology," translated by
Ward, p. 131.

WATER

99

Table of Latent Heats of Evaporation

Temper-

Sub tance

Formula

ature op
VAPOR-
IZATION

Latent Heat 0?
Vaporization

Water

H20

100°

536 Calories

Ammonia

NH3

295

Bromine

Br2

61.5

43.7

Chlorine

Cl2

-22

67.4

Iodine

I2

174

23.9

Hydrofluoric acid . .

HF

360

Oxygen

o2

-188

58

Nitrogen

N2

49.8

Phosphorus . . . .

P

287

130.4

Mercury

Hg

350

62

Sulphur

S2

316

362

Nitrous oxide . . .

N20

100.6

Nitric acid ....

HNO3

115

Sulphurous oxide . .

S02

0

91.2

Sulphuric oxide . . .

S03

18

147.5

Sulphuric acid . . .

H2SO4

326

122.1

Thionylchloride . .

SOCl2

82

54.5

Arsenic chloride . .

AsCl3

69.7*

Phosphorus trichloride

PCI3

67.2*

Stannic chloride . .

SnCU

46.8*

Silicon chloride . . .

SiCL.

37.3

Carbon dioxide . . .

C02

72.2

Carbon disulphide . .

CSa

0

90

Carbon tetrachloride .

CCI,

0

52

Cyanogen

(CN)2

0

103

Hydrocyanic acid . .

HCN

20

211*

Methyl alcohol . . .

CH3OII

0°

289.2

Ethyl alcohol . . .

r.IUHI

0

^:;«J.5

Amyl alcohol

CbHuOH

131

120

Cetyl alcohol . . .

QeHuOB

58.5

Hexane

CHM

68

79.4

Methyl chloride . .

CH3C1

0

!»<;.9

* Total heat of vaporization.

100 THE FITNESS OF THE ENVIRONMENT

Temper-

Substance

Formula

ature of
Vapor-
ization

Latent Heat of
Vaporization

Ethyl bromide . . .

C2H5Br

38.2

60.4 Calories

Amyl iodide .

C5HtlI

47.5

Aldehyde . .

CH3.CHO

136.4

Chloroform .

CHCl,

0

67

Ether . . .

(C2H5)20

34.9

90.4

Acetone . .

CH3.CO.CH3

56.6

125.3

Formic acid .

HCOOH

103.7

Acetic acid . .

CH3COOH

118

84.9

Acetic anhydride

(CH3CO)20

137

66.1

Dichlor-acetic acid

CHCloCOOH

138.4

79.1

Valerianic acid .

CsHio02

103.5

Ethyl acetate

C4H7O0

105.8

Acetyl chloride

CH3COCI

78.9

Acetonitrite . .

CH3CN

81.5

170.6

Ethyl amine .

C2H5NH2

146.2

Benzene .

Cell 6

0

109

Toluene . .

C6X15CH3

111

83.5

Nitro-benzene

C6H5N02

151.5

79.1

Aniline . .

C6H5NH2

93.3

Acetophenone

C6H5COCH3

203.7

77.2

Benzonitrite .

C6H5CN

191

87.7

Piperidine

C5HnN

105.8

88.9

Pyridine . .

C5H5N

115.5

101.4

that in the morning the surface temperature
rises about 0.6° per hour. This, however,
appears to account for but a small fraction
of the solar heat which the lake had taken
up ; the rest must have been expended in
evaporation. Another element of great im-
portance is the transparency of water. As a
result the rays of the sun are not absorbed

WATER 101

by the mere surface alone, but a considerable
layer of water near the surface receives the
heat.

At the equator the evaporation of the ocean
appears to be about 2.3 meters per year,1
which involves more than 1,000,000,000,000,-
000 calories of latent heat per square kilo-
meter. The amount of heat which is em-
ployed in evaporating water from 100 square
kilometers of the tropical ocean is accordingly
vastly more than all the energy employed in
the metabolism of the total population of
the United States, and it amounts to more
than 100,000,000 horse power. This is equiv-
alent to more than one horse power per square
meter day and night throughout the year.
To a greater or less extent all over the earth
this same process goes on, and as a result the
water vapor in the air probably averages
between 15 and 20 kilograms per square meter
of the earth's surface, an ample supply for
the formation of rain. The effect of this
enormous evaporation to moderate the tem-
perature of the tropics is very considerable;
but the heat which thus disappears is not
lost. Rendered latent at the place of evap-
oration, it is turned back into actual heat at

1 This and other similar facts will also be found in the
work of Hann.

102 THE FITNESS OF THE ENVIRONMENT

the point of condensation, and thus serves
to warm another and cooler locality.

This process, so vast that all the water power
of the globe may be regarded as its secondary
by-product, possesses, in respect to its ten-
dency to moderate and equalize the temper-
ature of ocean, of lakes, and of the climates
of all the earth, a maximal value. No other
liquid could, during the evaporation of a
given quantity of material, bind so much heat;
no other vapor could yield so much heat upon
condensation.

Quite as important to man as this great
power of meteorological regulation is the
corresponding physiological activity, evap-
oration of water from the skin and lungs.
In an animal like man, whose metabolism is
very intense, heat is a most prominent ex-
cretory product, which has constantly to be
eliminated in great amounts, and to this end
only three important means are available:
conduction, radiation, and the evaporation of
water. The relative usefulness of these three
methods varies with the temperature of the
environment. At a low temperature there
is little evaporation of water, but at body
temperature or above there can be no loss of
heat at all by conduction and radiation, and
the whole burden is therefore thrown upon

WATER 1 03

evaporation. The manner in which evapora-
tion becomes important in temperature reg-
ulation is well illustrated by the following cal-
culation from a chart of Rubner's.1 The
experiments upon which the chart is based
were made upon the dog, an animal which
lacks man's apparatus of sweat glands. The
values of the table are only approximate.

Temperature

Heat Loss by Evaporation

Degrees

Per Cent

9

16

11

19

13

22

15

25

17

27

19

30

21

32

23

32

27

36

29

42

31

58

33

64

35

79

In plants evaporation is even more impor-
tant than in animals. Evidently such adap-
tation of the physiological processes to the
conditions of the environment is enormously

i

favored by the high latent heat of evapora-
tion.2

1 Lusk, "The Science of Nutrition," p. 99.

2 A full discussion of this subject will be found in the
work of Lusk (see above), Chap. Ill, especially pp. 98-100.

104 THE FITNESS OF THE ENVIRONMENT

There is still another beneficial result of
this property : the great variation in the vapor
tension of water which accompanies variation
in temperature. Vapor tension measures the
amount of vapor which is present in the
atmosphere when it is in contact with a liquid
and after it has become saturated with the
liquid's vapor. Now, according to a well-
known law, the rate of increase of vapor ten-
sion, or in other words the amount of vapor
which the air can hold, is greater the greater
the latent heat of vaporization.1 Hence,
degree by degree there is more variation in
the vapor tension of water than there could
be if the latent heat were lower. Such great
variability in the quantity of water which
the air can hold is in meteorology the most
important characteristic of aqueous vapor.
The relationship between vapor tension and
temperature (centigrade) is shown in the
accompanying table.

1 Near the freezing point an increase of 10° in temperature
doubles the amount of water which the air can hold. The
increase is proportional to the latent heat of vaporization
according to the formulae

8.30.5 log ^ = fj(^)
p0 1.99 \ l0li /

where W stands for the latent heat of vaporization, p for vapor

tension, and T for temperature.

2 Arrhenius, "Kosmische Physik," p. 612.

2

WATER

Temperature

Vapor Tension

Degrees

Millimeters

0

4.58

10

9.18

20

17.41

30

31.55

40

54.07

50

92.17

80

355.47

90

526.00

100

700.00

105

These variations are what make possible both
the evaporation of water and its precipitation
as rain and as dew in the meteorological cycle.
And therefore the high latent heat of vapori-
zation of water is in still another manner a
most favorable circumstance in its effect upon
the organisms.

To sum up, this property appears to possess
a threefold importance. First, it operates
powerfully to equalize and to moderate the
temperature of the earth; secondly, it makes
possible very effective regulation of the tem-
perature of the living organism; and thirdly,
it favors the meteorological cycle. All of
these effects are true maxima, for no other
substance can in this respect compare with
water.1

1 This conclusion mav be contrasted with that of Whcwell
(Bridgewater Treatise, p. 142). He includes the expansion of

water by heat, the expansion of water by cold below 40°, the
expansion of water in freezing, the latent heats of melting and

106 THE FITNESS OF THE ENVIRONMENT

c

THERMAL CONDUCTIVITY

The heat conduction of water is also a maxi-
mum among ordinary liquids, and, though
very low compared with good conductors like
metals, must favor the equalization of tempera-
ture within the living cells whose structure hin-
ders the establishment of convection currents.

Table of Heat Conductivities

Water 0.0125 Rubber 0.0004

Alcohol 0.00048 Tin 0.15

Ether 0.00034 Lead 0.08

Benzene 0.00033 Iron 0.16

Glycerine 0.00066 Copper 0.72

Crown glass .... 0.0016 Silver 1.10

D

EXPANSION BEFORE FREEZING

A final thermal property of water remains
to be considered; namely, its anomalous ex-
pansion when cooled at temperatures near
the freezing point. The facts are illustrated
by the accompanying table.

evaporation, and the rate of evaporation of water. It will
be seen that eighty years ago it was already possible to
make out a strong case for the fitness of water ; but it should
not be forgotten that at that time ideas were in some respects
still very vague, and comparative data few.

WATER

107

Temperature

Density of Water

Expansion 1 to .: l

c-

. ,■

Per cent

0

0.99987

0.01:;

1

0.!)!)!)!):;

0.007

2

0.99997

0.003

3

0.99999

0.001

4

1.00000

0.000

5

0.99999

0.001

6

0.99997

0.003

7

0.99993

0.007

8

0.99988

0.012

9

0.99981

0.019

10

0.99973

0.027

20

0.99824

0.176

30

0.99567

0.44

40

0.99233

0.77

50

0.98813

1.19

100

0.95934

4.07

This unique property of water is the most
familiar instance of striking natural fitness of
the environment, although its importance
has perhaps been overestimated.1 If, how-
ever, water, like all other common substances,

1 It scarcely merits the curious rhapsody of Prout. for
instance: "The above anomalous properties of the expan-
sion of water and its consequences have always struck us as
presenting the most remarkable instances of design in the
whole order of nature — an instance of something done ex-
pressly, and almost (could we indeed conceive such a thing
of the Deity), at second thought, to accomplish a particular
object." — Prout, Bridgewater Treatise, "Chemical Meteor-
ology and the Function of Digestion." London, 1834, pp.
249-250.

108 THE FITNESS OF THE ENVIRONMENT

steadily contracted on cooling, so that its
point of maximum density fell at the freezing
point, it is impossible to say how great would
be the disadvantage for living organisms.
Certain it is that life upon the earth would be
thereby very greatly restricted. For this prop-
erty, together with the by no means unique phe-
nomenon of expansion upon solidification,1 is
very largely responsible for the permanence
in liquid state of many bodies of water in
cold climates. In salt water the anomalous
contraction disappears, and the lack of paleo-
crystic ice is due to the density of ice and to
the great mass of the ocean and the movement
of its waters.2

There is an old experiment of Rumford's
which well illustrates what conditions must
have been had the contraction of water been
normal and ice denser than water.3 He
found that in a vessel filled with water, which
contains ice confined at the bottom, it is
possible to heat and even boil the superficial
portion of the water without melting the ice.
And so it would be with lakes, streams, and
oceans were it not for the anomaly and the

1 The density of ice at the melting point is 0.91674.

2 A full discussion of this subject will be found in S.
G unther's "Handbuch der Geophysik."

3 See Whewell's Bridgewater Treatise.

WATER 109

buoyancy of ice. The coldest water would
continually sink to the bottom and there
freeze. The ice, once formed, could not be
melted, because the warmer water would stay
at the surface. Year after year the ice would
increase in winter and persist through the
summer, until eventually all or much of tlir
body of water, according to the locality,
would be turned to ice. As it is, the tempera-
ture of the bottom of a body of fresh water
cannot be below the point of maximum den-
sity ; on cooling further the water rises ;
and ice forms only on the surface. In this
way the liquid water below is effectually pro-
tected from further cooling, and the body of
water persists. In the spring the first warm
weather melts the ice, and at the earliest
possible moment all ice vanishes.

Such are the important thermal properties
of water, and in briefest outline their unique
fitness for the living mechanism. No other
known substance could be substituted for
water as the material out of which oceans,
lakes, and rivers are formed, and as the sub-
stance which passes through the meteorolog-
ical cycle, without radical sacrifice of some
of the most vital features of existing condi-
tions. Ammonia in these respects is the only
substance now known which approaches the

110 THE FITNESS OF THE ENVIRONMENT

fitness of water. But not only is it almost
inconceivable that ammonia should ever occur
in sufficiently vast quantities upon a planet's
surface, but it is evident as well that am-
monia wholly lacks the qualification of anoma-
lous expansion, and also in some of the most
important of the other thermal properties
falls far short of water ; while in latent heat
of melting and in specific heat its advantage
over water is inconsiderable.

It is obvious that upon a body like the
earth the state of the oceans and the meteor-
ological phenomena are of the utmost impor-
tance to all living things. Unless these be
favorable, human experience and reflection
alike agree that life could not widely exist.
It seems, therefore, almost safe to say, on the
basis of its thermal properties alone, that
water is the one fit substance for its place in
the process of universal evolution, when we
regard that process biocentrically.

II

THE ACTION OF WATER UPON OTHER SUB-
STANCES

Although the thermal properties of water
make up the classical subject-matter for dis-
cussions of the fitness of the natural en-

WATER 1 1 1

vironment, other no less important physical
properties exist. Such especially arc those
characteristics of liquid water which in no
small measure determine the nature of the
resulting physico-chemical systems when other
substances, whether soluble or insoluble, crys-
talline or colloidal, are brought into contact
with it ; I mean the solvent power, the dielec-
tric constant, together with the related ioniz-
ing power, and the surface tension.

WATER AS A SOLVENT

As a solvent there is literally nothing to
compare with water. In truth its qualifi-
cations are on this point so unique and ob-
vious that nobody seems to have taken the
trouble to gather together the evidence, and,
accordingly, beyond the bare assertion, a brief
statement of the facts is not easy.1 In the
first place the solubility in water of acids,
bases, and salts, the most familiar classes of
inorganic substances, is almost universal.

1 Nearly the whole science of chemistry has been built
around water and aqueous solutions. A reference to anv text-
book will at once reveal the truth of this statement. At first
sight such a condition appears to be a matter of chance, but,
as one becomes more familiar with the true character of the
science, realization of a rational justification for the historical
fact steadily grows.

112 THE FITNESS OF THE ENVIRONMENT

Relatively few of these bodies are highly
insoluble; very many are exceedingly soluble
in water. Apart from their electrolytic dis-
sociation and hydrolysis, which will be later
discussed, the chemical changes wrought upon
such dissolved substances in solution are
commonly very unimportant. For chemical
inertness, depending upon great stability,
is a most significant characteristic of water,
and undoubtedly a highly advantageous one

as well.

On the whole the best evidence for the
efficiency of water as a solvent of inorganic sub-
stances is to be found in the data of geology.
Of all geological agents water appears to
have been by far the most active within the
periods of which investigation is made pos-
sible by the geological record.1 Rainfall,
the movement of surface streams and of
water beneath the ground, and wave action,
all contribute to the work of disintegration,
sedimentation, etc., partly by dissolution of
soluble material, partly by mechanical action.
But mechanical action is itself much in-
creased by the loosening which earlier dis-
solution has caused. In this manner the great
solvent power of water throughout its meteor-
ological cycle largely contributes to the mobil-

1 Geikie, "Textbook of Geology," pp. 447-597.

WATER 113

ization of many materials which could not
otherwise be brought to the organisms which
need them.

It has been calculated by Murray1 that
the total yearly run off of all the rivers of the
earth is about 6500 cubic miles, carrying
nearly 5,000,000,000 tons of dissolved mineral
matter and prodigious quantities of sediment.
The average composition of such water has
been estimated as follows : —

Parte per Million

Potassium as K20 2 40

Sodium as Na20 7 10

Lithium as Li20 0 20

Calcium as CaO 43 20

Magnesium as MgO 14.70

Manganese as M113O4 1 20

Iron as FeO 2 80

Aluminium as AI2O3 310

Silicon as Si02 16.40

Carbonic acid as C02 46

Phosphorus as P2O5 , q.SO

Nitric acid as N205 380

Sulphuric acid as S03 8

Chlorine as CI 3 70

Ammonia as NH3 0.07

Total mineral matter 152.97

It is, of course, almost exclusively to these
constant accessions that the ocean owes its
salinity, which in the course of time has
reached well-nigh inconceivable magnitude.
The common salt alone in the oceans of all

1 Russell, ''Rivers of North America," p. 80.

1

114 THE FITNESS OF THE ENVIRONMENT

the earth amounts to not less than 35,000,000,-
000,000,000 tons. Quite as significant of the
solvent power of water is the variety of
elements whose presence in sea water can be
demonstrated, thus proving that the total
store of them is in any case enormous. They
include hydrogen, oxygen, nitrogen, carbon,
chlorine, sodium, magnesium, sulphur, phos-
phorus, which are easily demonstrated;
further, arsenic, csesium, gold, lithium, ru-
bidium, barium, lead, boron, fluorine, iron,
iodine, bromine, potassium, cobalt, copper,
manganese, nickel, silver, silicon, zinc, alumin-
ium, calcium, and strontium.1

Equally striking is the evidence in regard
to the first stages of this geological process.
Under the action of water, aided, to be sure,
in many cases by dissolved carbonic acid,
every species of rock suffers slow destruction.
All substances yield in situ to the solvent
work of water, and the dissolved parts may
all be found in the great final reservoir, the
ocean. It has been proved that nearly
every one of the substances which are thus
set in motion upon the face of the earth are
placed under contribution by life, for bio-
chemical analysis reveals them as constitu-
ents of living organisms, absorbed either

1 Arrhenius, "Kosmische Physik."

WATER 115

on their way down from the mountain tops
to the ocean or by the marine flora and
fauna.

Not less valuable to the community of
living things than the dissolution of the rocks,
is the disintegration and transport of solid
material, largely dependent thereon, which
among its many results includes the prelim-
inary steps of soil formation. By these
familiar and enduring geological means chemi-
cal substances are mobilized in the greatest
variety of forms and conditions, and thus
rendered available for the living organism.
It is clearly evident from the chemist's long
experience with solvents that no other fluid
could permanently carry on this process with
such acceptable regularity and efficiency.
For no other chemically inert solvent can
compare with water in the number of things
which it can dissolve, nor in the amounts of
them which it can hold in solution ; and of
course any chemically active solvent must
sooner or later exhaust itself by its chemical
action, when the cycle must cease. Here,
then, is a fitness of water which is open to no
doubt.

Let us turn for further proof to the organ-
ism itself, taking blood serum as a source of
information. The composition of this sub-

116 THE FITNESS OF THE ENVIRONMENT

stance (in the case of the cow) is roughly as
follows : ' —

Parts per 1000

Water 913.6

Protein 72.5

Sugar 1.05

Cholesterine 1.24

Lecithine 1.68

Fat 0.93

Organic phosphoric acid 0.01

Na20 4.31

K20 0.26

CaO 0.12

MgO 0.45

CI 3.69

P205 0.08

Most of these substances are in solution,
and unquestionably a host of others are pres-
ent with them, in small and varying amounts.
Among these may be mentioned iodine,
bromine, iron, sulphates, urea, ammonia, ben-
zoic acid, amino-acids, etc. But indeed all
substances found in urine (see below) also
occur in blood. It cannot be doubted that
if the vehicle of the blood were other than
water, the dissolved substances would be
greatly restricted in variety and in quantity,
nor that such restriction must needs be ac-
companied by a corresponding restriction of
the life processes.

1 A full discussion of the following data may be found in
such works as those of Hammarsten and Abderhalden on
physiological chemistry.

WATER 1 1 7

The composition of the urine provides
another excellent illustration of the utility
of the solvent power of water. In the course
of its complex chemical processes a higher

organism produces a host of end products
which must be removed, and also finds itself
accidentally in possession of a great variety
of other useless substances which require
excretion. The solvent power of water is
one of the great factors in facilitating this
task. Human urine has been reported to
contain in solution the following substances:
urea, carbamic acid, creatinine, creatine,
uric acid, xanthine, guanine, hypoxanthine,
adenine, paraxanthine, heteroxanthine, epi-
sarkine, epiguanine, oxalic acid, allantoine,
hippuric acid, phenaceturic acid, benzoic acid,
phenolsulphuric acid, skatoxylsulphuric acid,
paraoxyphenylacetic acid, homogentisic acid,
urobiline, urochrome, uroerythrine, glucose,
levulose, lactose, numerous compounds of
glycuronic acid, glycine, alanine, leucine, tyro-
sine, and other amino-acids, various enzymes,
putrescine, cadavarine, and countless other
organic substances, chlorides, bromides, and
iodides, phosphates and sulphates, potassium,
sodium, ammonia, calcium, magnesium, iron,
carbonic acid, nitrogen, argon, etc.

Here again it is sure that such variety could

118 THE FITNESS OF THE ENVIRONMENT

not be attained with another solvent. It is
no exaggeration to say that except atmos-
pheric oxygen and carbonic acid, nearly all
the food of living organisms is water borne,
and all material in its passage into the body,
through the body, and out of the body nearly
always employs the same vehicle. Cer-
tainly no other form of transport would be so
efficient and so economical.

B

IONIZATION

If, therefore, aqueous solutions are, ap-
parently of necessity, the very basis of the
life processes, the state of substances when in
this condition, and also when in contact with
water, is of vital importance. Here two prop-
erties of water, the dielectric constant and
the surface tension, exert a cardinal influence.

Among the phenomena of solution those
which are related to electrolytic dissociation,
as suggested by the hypothesis of Arrhenius,
have deservedly received a great deal of at-
tention since the secure establishment of the
new science of physical chemistry in the
eighties of the last century. In the course
of time the belief that in aqueous solution
the molecules of all acids, bases, and salts
are more or less split into particles which bear

WATER 1 1 g

electrical charges has been universally ac-
cepted. These so-called ions arc the sourer
of nearly all the electrical phenomena of solu-
tion, whether in batteries, in the manifesta-
tions of animal electricity, or in simple con-
duction through an aqueous solution. But
the more familiar electrochemical processes
are by no means the only results of ioniza-
tion. An infinite number of chemical inter-
actions between dissociated bodies follow
inevitably. These changes are not, to be
sure, decisive and irreversible, but balanced
actions, which, however, vastly increase the
variety of substances that exist in water.

Let us consider, for example, a system which
has been made by dissolving in water the
simple salts sodium chloride, NaCl, potas-
sium bromide, KBr, and lithium iodide, Lil.
According to the ionization hypothesis, more
than half of the molecules of every one of
these salts will at once dissociate into ions as
follows : —

NaCl = Na + Cl

KBr = K + Br

LiI = Li + I

These reactions are balanced, and it is
confidently believed that the ions are con-

120 THE FITNESS OF THE ENVIRONMENT

stantly recombining to form molecules and
the molecules constantly dissociating once
more to form ions. At the same time, noth-
ing hinders the union of sodium ions with
bromine ions, or of any other pair of positive
and negative ions. Accordingly, the solu-
tion at once contains not only the three origi-
nal salts and the six different varieties of
ions, but also the following new molecules: —
sodium bromide, NaBr, sodium iodide, Nal,
potassium chloride, KC1, potassium iodide, KI,
lithium chloride, LiCl, and lithium bromide,
LiBr. All nine varieties of molecules and
all six of ions are concerned in a complicated
system of chemical reactions which are now
well understood, the state of equilibrium
depending upon known conditions. For in-
stance, if the solution be a moderately dilute
one and the original substances be present in
chemically equivalent quantities, about 90
per cent of the material will be in the ionic
state, each variety of ions making up about 15
per cent of the total, and about 10 per cent
will be in the form of molecules, each variety
constituting about 1.1 per cent.

There can be no doubt that ionization
plays a great part in determining the char-
acteristics of solutions of acids, bases, and
salts, and in bringing about the reactions which

WATER 121

occur among them, and between them and
other substances.

Such, then, is the process to which are due
most of the electrical phenomena and many
of the chemical phenomena of solutions, and
it is certain that the extent and variety of
ionization in water far surpass what is possi-
ble in any other solvent. One reason for this
is most simple. The ionizing substances are
so very much more often soluble in water
than in any other solvent, and when soluble
are in general so much more highly soluble,
that the opportunity for ionization in water
is quite unparalleled. Further, ionization in
solution unquestionably depends upon the
dielectric constant of the solvent, in accord-
ance with the principle first stated by Nernst
that the greater the dielectric capacity of tin'
solvent, the greater is the degree of electro-
lytic dissociation of substances dissolved in it.
when the conditions are otherwise the same.1

1 "The following consideration will make this principle
clearer: The positively and negatively charged ions would
unite to form electrically neutral molecules because <>f the
electrostatic attraction which exists between them ii' it were
not for the action of another and opposing force the nature <»f
which is as yet unknown. The equilibrium between these
two forces gives rise to the equilibrium between the ions and
the undissociated molecules, or determines the degree of dis-
sociation. When the dielectric constant i> increased, the

122 THE FITNESS OF THE ENVIRONMENT

This is the case because the tendency of the
electrically charged ions to reunite and form
electrically neutral molecules must be less
the greater the dielectric constant of the sol-
vent. Now the dielectric constant of water
is nearly the highest at present known, and
therefore ionization in water is on that account
also more extensive than in almost any other
solvent.

Finally, for reasons that are not yet under-
stood, the process of ionization in other sol-
vents than water is a much more complex
affair, and there can be no doubt that such
complexity limits the phenomena which are
dependent upon ionization.1

electrostatic attraction between the ions is alone weakened,
and hence the degree of dissociation is increased." — Le
Blanc, "A Textbook of Electro-Chemistry." New York,
1907, p. 147.

1 "It would be natural to expect that the conceptions
which have been found serviceable in the case of solutions in
water could be applied directly to solutions in other solvents,
keeping in mind that, according to the individual nature of
any given solvent, the degree of dissociation, the migration
velocity of the ions, and consequently the conductivity of a
solution of a given concentration would be different. It is
a noteworthy fact, however, that the behavior of non-aque-
ous is much more complicated than that of aqueous solutions.
This is shown especially by the investigation of the conduc-
tivity of solutions of various substances in liquid sulfur dioxide
made by Walden and Centnerszwer. Neither the law of the
independent migration of the ions, nor the law that by increas-

WATER 123

Physiologically, as researches of the last
twenty years clearly prove, the action of ions
is of fundamental significance. The brilliant
investigations of J. Loeb, and the long series
of studies by various other physiologists of
the influence of electrolytes upon colloids
form perhaps the most telling evidence for
this belief.1 At all events there is no ques-
tion that the simple equilibria between acids
and bases and salts are of extreme importance
in physiological processes. They lie at the
very basis of the structure of all protoplasm,

ing dilution the conductance approaches a maximum value,
nor, finally, the dilution law, was found to hold. Molecular
weight determinations carried out at the same time by the
boiling-point method gave normal values for non-electrolytes,
and abnormally large values for electrolytes, whereas abnor-
mally small values would be expected. This indicates that
association has taken place, to a considerable extent, which
in all probability takes place not only between molecules of
dissolved substance, but also between these molecules and
those of the solvent. Considering these circumstances, it
is very fortunate for the advance of the sciences of chemistry
and electro-chemistry that such complications arc generally,
although not always, absent in the case of aqueous solutions.
It is due to this fact that it has been possible to deduce simple
laws from a study of such solutions." — Le Blanc, "A Text-
book of Electro-Chemistry." New York, 1907, pp. H2-1 \:\.
1 Full discussion of such subjects will be found in the
"Dynamics of Living Matter," by Loeb, and in his contribu-
tion to Oppenheimer's "Handbuch der Biochemie," as well
as in Hober's " Physikalische Chemie der Zelle und der
Gewebe."

124 THE FITNESS OF THE ENVIRONMENT

and the sure and definite relations between
such bodies provide, as it were, a secure foun-
dation for the more complex organic structures.
More obvious is the value of ions as sources
of electricity. If the older electro-physiology
of the third quarter of the nineteenth cen-
tury has proved in some respects a sterile
field, there can yet be no doubt that more
subtly, and quite apart from the nervous im-
pulse and the peculiar phenomena of electrical
fishes, electrical phenomena are everywhere
involved in the most intimate of the physio-
logical processes.

Even without further discussion of a sub-
ject that must soon lead into difficult and
highly technical considerations, I feel sure
that the existence of another important fitness
of water is patent. For ions are evidently
a real contribution to the richness of the
environment. They enhance the Variety of
chemical substances and of chemical reactions ;
they constitute a group of singularly mobile
( chemical agents; they provide electricity;
and, finally, aqueous solutions are by far the
best source of ions.

It must be pointed out before leaving this
subject that the dielectric constant, hence
the ionizing power, is somehow related to
various other properties of the solvent. In

WATER

125

the accompanying table KD stands for the
dielectric constant, IIV for the latent heat
of vaporization, and KH for the absolute
conductivity for heat. It is to be observed
that on the whole all three quantities decrease
simultaneously. These properties are also
related to the critical pressure, to the van
der Waals constant a, and to the molecular
volume at the boiling point.

Solvent

Water, H20

Methyl alcohol, CH3OH . . .
Ethyl alcohol, C2H50H . . .
Formic acid, H • COOH . . .
Acetic acid, CH3 ■ COOH . .

Ammonia, NH3

Methylamine, CH3 • NH2 . .
Sulphurous oxide, SO2 . . .
Acetone, CH3 • CO • CH3 . . .
Ethylacetate, CH3 • CO • O • C2H5

Benzene, CeHe

Toluene, CaHs • CH3 ....

Ether, (QHs^O

Chloroform, CHCI3 ....
Tetrachlormethane, CCI4 . .
Stannic chloride, SnCl4 . . .

KD

Hv

81.7

536.5

32.5

267.5

21.7

205

57.0

103.7

6.5

89.8

16

329

<10.5

14

92.5

20.7

125.3

5.85

86.7

2.26

93.5

2.31

83.6

4.3G

84.5

4.95

58.5

2.18

46.35

3.2

30.53

K

17

0.154

0.0495

0.0423

0.0648

0.0472

0.0348
0.0333
0.0307
0.0303
0.0288
0.0252

Such evidence clearly suggests that some
of the manifold fitnesses of water proceed
from a single cause or group of causes. For
the present, however, these relationships are

126 THE FITNESS OF THE ENVIRONMENT

obscure, and in any case there seems to be
no immediate hope of bringing them into
connection with the science of biology.

C

SURFACE TENSION

Of all common liquids, except mercury,
water has the greatest surface tension.

Table of Surface Tensions

Water 75

Carbonic acid 1.8

Ammonia 41.8

Mercury 436

Benzene 28.8

Methyl alcohol 23

Ethyl alcohol 22

Ether 16.5

Glycerine 65

Acetone 23

Formic acid 37.1

Acetic acid 23.5

Chloroform 26

This fact is of enormous moment in biology,
most obviously perhaps in its influence upon
the soil. For surface tension and density
determine the height to which a liquid will
rise in a capillary system, and thus it comes
about that the principal factor in bringing
water within reach of plants is the exceptional
surface tension of water. The nature of the
case is clearly explained by Hilgard. "The

WATER 127

liquid water held in the pores of the soil, in
the form of surface films representing the
curved surface seen in capillary tubes, and
therefore tending to cause the water to move
upwards, as well as in all other directions,
until uniformity of tension is established, is
of vastly higher importance to plant growth
than hygroscopic moisture. It not only serves
normally as the vehicle of all plant food ab-
sorbed during the growth of the usual crops,
but also, as a rule, to sustain the enormous
evaporation by which the plant maintains,
during the heat of the day, a temperature
sufficiently low to permit of the proper op-
eration of the processes of assimilation and
building of cell tissue." *

The rise of water in capillary systems re-
sembling soil, under the action of surface
tension, may be as much as ten feet. In soil
itself the highest rise under the usual circum-
stances is unquestionably as much as four
or five feet; but if the surface tension of
water were like that of most liquids it could
be, under similar conditions, but two or three
feet. There seems to be little doubt that the
rise of fluids in tall plants is also in large
part due to the action of surface tension, and
accordingly it must be much favored by the

1 Hilgard, "Soils." New York, 1907, p. 201.

128 THE FITNESS OF THE ENVIRONMENT

magnitude of that quantity in the case of
water.

Finally, surface tension is of great impor-
tance, indeed in simple cases is the one effective
agent, in the phenomenon called adsorption.1
On the basis of thermodynamical considera-
tions first developed by Willard Gibbs, it is
easy to show that whenever the dissolution
of a substance changes the surface tension
of a solvent, the distribution of the dis-
solved substance will not be strictly homo-
geneous. If the solution has a lower surface
tension than the solvent, the surface of the
solution will become more concentrated than
the interior; or if the surface tension of the
solution be greater than that of the solvent,
the surface of the solution will become less
concentrated than the interior. This result,
quite insignificant in simple solutions, becomes
a matter of much moment when, as in the
case of suspensions of fine particles like ani-
mal charcoal, in emulsions, jellies, or any
other system of like disperse heterogeneity
of physical constitution, there occurs very
great increase of surface area. Then it is

1 A familiar example of adsorption is the use of bone-
black to decolorize sirup in the process of sugar refining.
The colored matters are almost completely removed from
solution, and cling to the surface of the charcoal.

WATER log

that adsorption becomes a factor of the great-
est weight; for, other things being equal,
the total force of surface tension in a system
is proportional to the area of surface. Under
these circumstances dissolved substances are
no longer distributed with any approach to
equality or regularity in the system, but they
collect at the surface in very great quantities,
and in the most irregular manner.

Now of all known physical structures there
is none which rivals protoplasm in its fine
complexity, and adsorption is therefore un-
questionably a prominent agent in deciding
its physico-chemical constitution. Moreover,
adsorption influences and complicates almost
every process of chemical physiology, for no
product of life is without its colloids, i.e. sub-
stances which are finely divided and there-
fore endowed with great surface areas. In
truth colloids are probably quite essential to
fine complexity, and so to every conceivable
form of life.1

The evidence for this universal importance

1 "Eines aber mochte ich beliaupten, welches auch immer
die stoffliche Zusammensetzung jener Lebewesen (living
organisms in another world) sein mag : es miissen Kolloide
sein. . . . Welcher andere Zustand, ausser dem Kolloiden,
konnte derart veranderliche, derart plastische Formen bilden
und ware doch im stande, diese Formen, wenn notig, unver-
anderlich zu wahren." — Bechhold, I.e., p. 194.

130 THE FITNESS OF THE ENVIRONMENT

of adsorption in biology is not to be briefly
presented, but it may be found in almost
endless profusion in such works as those of
Freundlich and Bechhold.1

It must not be supposed that the phenomena
of adsorption in biology are simple and exactly
understood. What is certain is that they
are universal, and that surface tension lies
at the root of the matter. This is because
all living things are colloidal, and I am in-
clined to think that most physiologists will
admit that life without colloids is probably
unthinkable, even in a world very differently
constituted from our own. Colloidal struc-
tures are, in fact, the first and greatest factors
in physical complexity of organization, and
the principal force, unless it be in exceptional
cases an electrical charge due to ions, which
operates upon the colloidal structures is sur-
face tension. This, then, is another striking
fitness of water above all other things.

Such are the facts which I have been able
to discover regarding the fitness of water for
the organism. The following properties ap-
pear to be extraordinarily, often uniquely,

1 Freundlich, "Kapillarchemie." Leipzig, 1909. Bech-
hold, "Die Kolloide in Biologie und Medizin." Dresden,
1911.

WATER 131

suited to a mechanism which must be complex,
durable, and dependent upon a constant
metabolism: heat capacity, heat conductiv-
ity, expansion on cooling near the freezing
point, density of ice, heat of fusion, heat of
vaporization, vapor tension, freezing point,
solvent power, dielectric constant and ionizing
power, and surface tension.1

In no case do the advantages which these
properties confer seem to be trivial ; com-
monly they are of the greatest moment;
and I cannot doubt, even after allowances
have been made for the probability of occa-
sional fallacies in the development of an argu-
ment which, though simple, is beset with many
pitfalls, that they are decisive. Water, of its
very nature, as it occurs automatically in the
process of cosmic evolution, is fit, with a fitness
no less marvelous and varied than that fitness
of the organism which has been won by the
process of adaptation in the course of organic
evolution.

If doubts remain, let a search be made for

1 Contrasting this statement with that of Whewell in his
Bridgewater Treatise, it is evident that while the progress
of science has provided much novel information, and elim-
inated many false views, the present situation differs from the
earlier one only in the better definition of the issue, and in
our modern freedom from metaphysical and theological
associations.

132 THE FITNESS OF THE ENVIRONMENT

any other substance which, however slightly,
can claim to rival water as the milieu l of
simple organisms, as the milieu interieur of
all living things, or in any other of the count-
less physiological functions which it performs
either automatically or as a result of adapta-
tion.

In truth Darwinian fitness is a perfectly
reciprocal relationship. In the world of
modern science a fit organism inhabits a fit
environment.

1 Here and elsewhere the word " milieu " has been employed
when it is desired to express only that part of the conception
of environment which is involved in the literal meaning of
the word, leaving to environment the added significance of
that which provides food.

CHAPTER IV
CARBONIC ACID

TWO chemical individuals stand alone in
importance for the great biological
cycle upon the earth. The one is water, the
other carbon dioxide. The one, for reasons
which we have just reviewed, is the most
familiar of all the varieties of matter. The
other rarely is seen except by chance, and with-
out scientific research never could have been
known for what it is in value to living things.
Yet these two simple substances are the com-
mon source of every one of the complicated
substances which are produced by living
beings, and they are the common end prod-
ucts of the wearing away of all the constitu-
ents of protoplasm, and of the destruction of
those materials which yield energy to the
body.1

1 A man weighing 60-70 kilograms excretes daily the fol-
lowing quantities of material : —

Water 2500-3500 grams

Carbon dioxide .... 750-900 grams

All other substances . . 00-1-25 grams

133

134 THE FITNESS OF THE ENVIRONMENT

Once perhaps the atmosphere of the earth
consisted chiefly of water and carbon dioxide;
but cooling has caused the condensation of
most of the water, and geological processes,
more recently aided by the action of vegetation
with coal and peat formation, have removed
nearly all of the carbon dioxide. The latter
transformations have resulted in the substitu-
tion of oxygen in the atmosphere. However,
the interior of the earth continues to deliver
through volcanoes large amounts of carbon
dioxide, and thus the original source of atmos-
pheric carbon dioxide persists as a diminish-
ing supply.

To-day carbon dioxide makes up only a
little more than 0.03 per cent by volume of
the whole atmosphere, approximately 4.6
kilograms per square meter of the earth's
surface, or about 2,300,000,000,000 metric

Water is, therefore, three fourths, carbon dioxide one fifth,
of the total, and all other substances amount to but 2 to 3
per cent.

In like manner the materials ingested by an ordinary green
plant are proportioned, water making up more than nine
tenths, and carbon dioxide amounting to fully five times the
sum of all other substances combined.

Needless to say, a large part of the water which enters
and leaves plants and animals has had no real share in their
organization. It is merely the bearer of dissolved substances
or the means, through evaporation, of lowering the tempera-
ture of their bodies.

CARBONIC ACID

135

tons for the whole earth.1 In the oeean the
amount of carbonic acid is about 0.1 gram per
liter, or approximately 0.01 per cenl by
weight. Here, however, much (lie larger
part is in chemical union with bases, chiefly
in the form of bicarbonates.-

There can be no doubt that the physical
properties of carbon dioxide are less important
to the living organism than are those of water.
But indeed the characteristics of water so
largely determine the nature of the environ-

1 The composition of dry air is as follows : —

Per Cubic Meter

Nitrogen . .
Oxygen . .
Argon . . .
Carbon dioxide

Nitrogen . .
Oxygen . .
Argon . . .
Carbon dioxide

2 See below in the discussion of the alkalinity of the ocean.

136 THE FITNESS OF THE ENVIRONMENT

ment and the conditions within the organism
alike, that this is necessarily the case. How-
ever, the less conspicuous substance is not
without its physical fitnesses, and we must
now turn to them.

SOLUBILITY

The most obvious of the properties of car-
bonic acid is its all-pervasiveness. Originally
formed in vast quantities by the cosmic pro-
cess, and accumulated in the atmosphere, the
store has been steadily replenished there by
vulcanism. It is probable that of the enor-
mous quantities now deposited as limestone
in the earth's crust, a quantity sufficient to
yield an atmospheric pressure greater ten-
fold than the present atmospheric pressure,
only a fraction was at any one time actually
gaseous. For it happens that the presence
of carbonic acid in the atmosphere insures the
occurrence of greater, or at least nearly equal,
quantities in the ocean and in all the natural
waters of the earth. This is due to the solu-
bility of carbon dioxide, to the magnitude of
its absorption coefficient in water.

The absorption coefficient is the volume
of gas absorbed by one liter of liquid when

CARBONIC ACID 137

the gas pressure^ is one atmosphere. Accord-
ing to the law of Henry, however, the absorp-
tion of the gas is always proportional to its

Table of Absorption Coefficients at 0°

Oxygen 0.01!)

Hydrogen 0.0*1

Nitrogen 0.0*1

Carbon monoxide 0.035

Carbon dioxide 1.797

Sulphurous oxide 79.79

Ammonia 1299

partial pressure in the atmosphere, and there-
fore the absorption coefficient measures the
ratio, after equilibrium has been attained,
between the concentration of a substance in
solution and in the gaseous state, no matter
what that concentration may be.

The absorption coefficient is not constant
under all circumstances, and varies especially
with the temperature.

Table of Absorption Coefficients of C02

Temperature Absorption Coefficient

0° 1.797

10° 1.185

20° 0.901

37.29° 0.563

100° 0.2 44

It will be seen from the tables that, differ-
ing from most gases, carbon dioxide has an
absorption coefficient nearly equal to one, and

138 THE FITNESS OF THE ENVIRONMENT

that for the ordinary temperature of the earth's
waters, where they are in contact with car-
bonic acid gas, it is very close indeed to 1.0.
Hence, when water is in contact with air, and
equilibrium has been established, the amount
of free carbonic acid in the water is almost
exactly equal to the amount in the air. Unlike
oxygen, hydrogen, and nitrogen, carbonic acid
enters water freely ; unlike sulphurous oxide
and ammonia, it escapes freely from water.
Thus the waters can never wash carbonic acid
out of the air, nor the air keep it from the
waters. It is the one substance which thus,
in considerable quantities relative to its total
amount, everywhere accompanies water.1 In
earth, air, fire, and water alike these two sub-
stances are always associated.

Accordingly, if water be the first primary
constituent of the environment, carbonic acid
is inevitably the second, — because of its
solubility possessing an equal mobility with
water, because of the reservoir of the at-
mosphere never to be depleted by chemical

1 "Carbonic acid being more soluble than the other gases,
is contained in rain water in proportions between 30 and 40
times greater than in the atmosphere." — Geikie, "Text-
book of Geology." 4th ed., Vol. I, p. 449, 1903.

It must not be forgotten that carbonic acid in subterranean
water, by which so much geological change is accomplished,
originates, not in the air, but from organic matter in the soil.

CARBONIC ACID 189

action in the oceans, lakes, and streams. In

truth, so close is the association between these
two substances that it is scarcely con-eel logi-
cally to separate them at all; together they
make up the real environment and I hey never
part company. Carbonic acid thus possesses
the first great qualification of a food: its
occurrence is universal and its mobility a
maximum. This is due to the fact that its
absorption coefficient is on the average ap-
proximately one, the most favorable value.

Needless to say the absorption coefficient
of carbonic acid is also of great importance
in many physiological processes, chiefly per-
haps in excretion. In the course of a day a
man of average size produces, as a result of
his active metabolism, nearly two pounds of
carbon dioxide. All this must be rapidly re-
moved from the body. It is difficult to im-
agine by what elaborate chemical and physical
devices the body could rid itself of such enor-
mous quantities of material were it not for
the fact that, in the blood, the acid can cir-
culate partly free ' and, in the lungs, by a pro-
cess which under ordinary circumstances has
all the appearances of a simple physical phe-

1 Of the total carbonic acid of the blood 5-10 per cent
exists as the free acid, partly in the plasma, partly in the cor-
puscles.

140 THE FITNESS OF THE ENVIRONMENT

nomenon,1 can escape into air which is charged
with but little of the gas.2 Were carbon
dioxide not gaseous, its excretion would be
the greatest of physiological tasks ; were it
not freely soluble, a host of the most universal
existing physiological processes would be im-
possible.

II

ACIDITY

The only other property of this substance
which calls for consideration at this point is
its acid nature and strength. Very few min-
erals are freely soluble in pure water, and
nearly all yield to the process of weathering
far more readily because of the carbonic acid
which all natural waters contain.3 The latter

1 The determination of the exact nature of the process
by which carbonic acid is excreted across the lung membrane
is one of the standing difficulties of physiology, but we need
not here enter upon its consideration.

2 Expired air contains on the average more than 4 per cent
by volume of carbonic acid.

3 "A few minerals (halite, for example) are readily soluble
in water without chemical change, and without the aid of any
intermediate element; hence the copious brine-springs of
salt regions. In the great majority of cases, however, solu-
tion is effected through the medium of carbonic acid or other
reagent. Limestone is soluble to the extent of about 1 part
in 1000 of water saturated with carbonic acid. The solution
and removal of lime from the mortar of a bridge or vault,

CARBONIC ACID m

constituent is probably a necessary adjuvant
in the most far-reaching geological phenom-
ena. Indeed, it is the united net ion of water
and carbonic acid, aided in lesser degree by
nitric acid, which has been formed in the atmos-
phere by electrical action, and by acid prod-
ucts of vegetation, which sets free the in-
organic constituents of the earth's crust and
turns them into the stream of metabolism.

But apart from the solvent action of car-
bonic acid, there is another group of phenomena
which depend upon its acid character. These
must now be explained. They are the neu-
trality or faint alkalinity of the ocean, and of
protoplasm.

According to the modern theory of solution,
water itself, like the dissolved electrolvtes,
is dissociated into ions, though only to a very
slight degree.1 The reaction is expressed as
follows : —

H20=H+OH

and the deposit of the material so removed in stalactites and
stalagmites, likewise the rapid effacement of marble epi-
taphs in our church yards, are instances of this solution. . . .
Among the sulphates, gypsum is the most important example
of solution. It is dissolved in the proportion of aboul 1
part in 400 parts of water. Even silica is abstracted from
rocks by natural waters." — Geikie, "Geology," pp. 451-452.
1 For a discussion of this subject the textbook of M.llor,
"Chemical Statics and Dynamics," p. 405, may be consulted.

142 THE FITNESS OF THE ENVIRONMENT

If the water be pure, the concentrations of
hydrogen and hydroxyl ions are necessarily
the same, for water is electrically neutral. A
variety of independent methods of estimation
have shown that at 25° (centigrade) this
concentration amounts almost precisely to
0.0000001N, in the ordinary units.1 This
corresponds to 0.0000001 gram of ionized
hydrogen and 0.0000017 gram of ionized
hydroxyl in 1000 grams of water. Further,
the theory of solution explains acidity in
water by the occurrence of hydrogen ions,
formed from dissolved electrolytes, in excess
of hydroxyl ions ; and alkalinity by a similar
excess of hydroxyl over hydrogen ions. Neu-
trality is then the condition when, as in pure
water, the two concentrations are equal. In
short, expressing the concentration of ionized

1 Concentrations are expressed in terms of chemical
equivalents, gram-molecules, or moles. N (normal) is the
symbol for this unit. The values of the concentration of
ionized hydrogen at neutrality as estimated by different
investigators are as follows : —

6. X10"7 Kohlrausch 1884

1.0 XKT7 Ostwald 1893

1.1 X 10 7 Arrhenius, Shields 1893

1.2 X10"7 Wijs 1893
0.9 X10"7 Kanolt 1907
1.02 X 10"7 Heydweiller 1909
1.02 X10-7 Lunden 1907

CARBONIC ACID 148

* +
hydrogen by (H) and of ionized hydroxyl by

(OH) : -

If (H) = 0.0000001 N = (OH)

the solution is neutral;

if (H) > 0.0000001 N > (OH)

the solution is acid;

if (H) < 0.0000001N < (OH)

the solution is alkaline.

It remains to point out that implicit in
these definitions is the well-founded hypothesis
that in water the concentrations of hydrogen
and hydroxyl ions vary inversely, so that
with constant temperature under all circum-
stances their product is constant : ! —

(H) X (OH) = K

Substituting in this equation the value
0.0000001 of the concentrations at neutral-
ity, we obtain the value

K - 0.00000000000001

u ra\ 0.00000000000001
whence (H) =

(OH)

1 This corresponds with the requirements of the Mass-
Law.

144 THE FITNESS OF THE ENVIRONMENT

Whenever a weak acid is present in aqueous

solution in company with such bases sa

sodium, potassium, calcium, magnesium, etc.,

which are invariable constituents of the ocean,

blood, protoplasm, etc., provided the acid be

in excess, it is a simple matter to determine

the reaction, which can best be measured by

+
the values of (H) and (OH), following the

considerations above.

Now there is a certain characteristic prop-
erty of an acid, its ionization constant, k,
which measures its tendency to dissociate
in aqueous solution, thereby to produce hydro-
gen ions, and hence to increase the intensity
of acidity. Strong acids have ionization con-
stants which are of the order of magnitude of
1.0, weak acids of the order of magnitude of
0.0001, the weakest acids, 0.00000001, or less.

Table of Ionization Constants

HC1, HN03, etc 1.

H3P04 0.011

H3As04 0-005

HNO2 0.0005

H2C03 0.0000003

NaH2P04 0.0000002

H2S 0.000000091

H3BO3 0.0000000007

Na2HP04 0.00000000000036

It has been discovered that in the general
case above discussed the concentration of

CARBONIC ACID 145

ionized hydrogen is always almosl exactly
proportional to the ratio of free acid to Bait,
and is equal, in very close approximation,
to the product of this ratio by the ionization

constant of the acid. That is to say, repre-
senting free acid by HA and sail by BA,

+
whence, if Jc = (H)

HA
BA

From this relationship, therefore, follows the
conclusion, fully established by experiment,
that whenever in such a solution the excess
of acid, HA, is chemically equivalent to the
quantity of salt, BA, the hydrogen ion concen-
tration is almost exactly equal to the ioniza-
tion constant of the acid. But the ionization
constant of carbonic acid (first hydrogen atom)
is 0.0000003. Hence in a solution containing
exactly equivalent quantities of free earl ionic
acid and, for example, sodium bicarbonate,
the hydrogen ion concentration must be
0.0000003 N. Further, since

HA _ (H)
BA k

146 THE FITNESS OF THE ENVIRONMENT

if the amount of acid be ten times the amount
of salt (ll^j = loY the hydrogen ion concentra-
tion must be 0.000003 N, and if the reverse

be the case ( =f = — ) the value must be

VBA 10/

0.00000003 N.

The range of variation of concentration of
hydrogen ions in the usual solutions of the
chemical laboratory considerably surpasses
the limits 1.0 N and 0.00000000000001 N. In
comparison with such enormous differences
those between 0.000003 N and 0.00000003 N are

J_ . 1

100 * 100,000,000,000,000,
Hence ordinarily it is quite accurate enough
to speak of any solution containing both
free carbonic acid and a bicarbonate, when
the disparity between the concentrations of
the two substances is not very great, as of
constant neutral reaction. For, obviously,
the neutral point, which at a temperature of
25° amounts to a concentration of hydrogen
and hydroxyl ions 0.0000001 N, falls well
within the narrow range of reaction of such
solutions, being characterized by a ratio of
carbonic acid to bicarbonate of about 1:3.

Thus carbonic acid, like the almost equally
weak acids sulphuretted hydrogen and phos-

almost negligible (-J- : nOO.OOo)

CARBONIC ACID 1 fl

phoric acid (after its first hydrogen baa been
neutralized by base), has the remarkable
property of preserving a neutral reaction

whenever it exists in solution will) its sails,
provided there be an execs, of acid. All acids
whose strength is even a little cither greater
or less than carbonic acid lack the property.1

This characteristic of carbonic acid is of
the utmost significance, first by regulating
one of the most fundamental of physico-
chemical conditions, and secondly bv niv-
serving throughout nature the characteristic
chemical inactivity of water, which disappears
whenever the reaction becomes either appre-
ciably acid or appreciably alkaline. Almost
the only case of important geological action
due to acidity or alkalinity of water is the
action of fresh water, containing carbonic acid
itself, to weather the rocks. This process is,
however, self-limited, for the dissolved material
forms bicarbonates, and thus at once pro-
vides permanently inactive balanced solutions.

It is impossible to understand the efficiency
with which neutrality is preserved by carbonic
acid, without the actual discussion of a par-
ticular case. Let us therefore consider a solu-

1 Henderson, "The Relation between the Strength! of

Acids and their Capacity to Preserve Neutrality,*' American
Journal of Physiology, XXI, 173, 1908.

H. C. State College

148 THE FITNESS OF THE ENVIRONMENT

tion of 1 kilogram of carbon dioxide in 100
liters of water, to which sodium hydrate is
being added. At the beginning of the experi-
ment the hydrogen ion concentration will be
approximately 0.0001 N, almost exactly one
thousand times that at neutrality, and the
hydroxyl ion concentration 0.0000000001 N,
one one-thousandth that at neutrality. If, now,
the sodium hydrate be added to the solution
in successive portions, the change of reaction
will be as indicated in the following table: —

Amount of

(H)

(OH)

Intensity compared with
a Neutral Solution of

NaOH

Acidity

Alkalinity

Grams
0

0.0001 N

0.0000000001 N

1000

0.001

50

0.0000052

0.000000002

52

0.02

100

0.0000024-

0.000000004

24

0.04

150

0.0000015

0.000000006

15

0.06

200

0.0000011

0.000000009

11

0.09

250

0.0000008

0.000000012

8

0.12

300

0.0000006

0.000000017

8

0.17

350

0.0000005

0.000000020

5

0.20

400

0.0000004

0.000000025

4

0.25

450

0.0000003

0.000000033

3

0.33

500

0.00000025

0.00000004

2.5

0.4

550

0.00000020

0.00000005

2.0

0.5

600

0.00000015

0.00000007

1.5

0.7

650

0.00000012

0.00000008

1.2

0.8

700

0.00000009

0.00000011

0.9

1.1

750

0.00000006

0.00000017

0.6

1.7

800

0.00000004

0.00000025

0.4

2.5

850

0.00000002

0.0000005

0.2

5.0

CARBONIC ACID 149

From the tabic4 it appears that the first
50 grams of alkali reduce the hydrogen ion
concentration to but 50 times that of neutral

solutions, and 200 grams of alkali have made
it only about 10 times that of pure water, in
spite of the fact that there are more than
750 grams of free carbonic acid still present
in the solution. So much acidity can at once
be obtained by dissolving merely 0.004 gram
of hydrochloric acid in 100 liters of water.
Thereafter neither acidity nor alkalinity sur-
passes this intensity until 450 grams more of
sodium hydrate have been added to the solu-
tion. Yet in pure water 0.005 gram of sodium
hydrate would make the reaction more alka-
line than that.

Such is the case when the equilibrium is
homogeneous, i.e. in an isolated solution.
But when, in similar cases, an atmosphere
containing carbon dioxide is present, the con-
ditions are still more striking. Suppose, for
example, a solution of 100 liters containing 1
kilogram of sodium bicarbonate in equilib-
rium with an atmosphere containing 1 gram
of carbon dioxide per liter. Let hydrochloric
acid be added in successive small portions to
the solution. Further let the solution be
constantly stirred and shaken, and let the
experiment be conducted slowly, so that there

150 THE FITNESS OF THE ENVIRONMENT

shall always be equilibrium between the car-
bonic acid in the solution and in the atmos-
phere. Further, let the temperature be such
that the absorption coefficient of carbon
dioxide shall be 1.000. Then the successive
states of the solution will be approximately
as recorded in the following table: —

HCl

H2CO3:

Added

NaHCOj

Grams

0

2.27:11.9

10

2.27: 11.5

50

2.27 : 10.0

100

2.27: 8.2

150

2.27: 6.3

200

2.27: 4.4

250

2.27: 2.6

300

2.27:0.68

310

2.27 : 0.31

318

00

320

330

(H)

000000057

000000059

000000068

000000083

000000108

000000154

00000026

0000010

0000022

00026

00045

0027

N

Relative

(OH)

Acidity

0.000000176 N

0.57

0.000000170

0.59

0.000000147

0.68

0.000000120

0.83

0.000000093

1.08

0.000000065

1.54

0.000000039

2.6

0.000000010

10

0.0000000045

22

0.00000000039

260

0.00000000022

450

0.000000000037

2700

Relative
Alka-
linity

1.76
1.70
1.47

1.20

0.93

0.65

0.39

0.10

0.045

0.0039

0.0022

0.00037

From the beginning of the experiment until
almost 250 grams of hydrochloric acid have
been added, neither alkalinity nor acidity is
double in intensity the values wThich obtain
in a perfectly neutral solution. This amounts
to a constancy of reaction which, until a few
years ago, was scarcely known to the chemist
at all. Such close approach to neutrality

CARBONIC ACID 151

can be attained with pure water only after
elaborate and very difficult purification, yet
in the presence of carbonic acid it is the natural
condition. Of course the case above dis-
cussed is an extreme one. In nature the con-
centrations of dissolved substances arc less,
the mixing less efficient, and the variations of
reaction a little greater. There is also, in
nature, likely to be a considerable excess of
bicarbonate over free carbonic acid present.
The cause of the greater constancy of re-
action in the case of the heterogeneous equi-
librium is simple enough. At the beginning of
the experiment the free carbonic acid of the
solution is exactly in equilibrium with that of
the atmosphere. Accordingly, when hydro-
chloric acid is poured in and reacts with so-
dium bicarbonate to form sodium chloride and
more carbonic acid,

NaHC03 + HC1 - NaCl + H20 + C02

every bit of the latter escapes to the atmos-
phere, and the total amount of acid is just
what it was before. But a certain amount of
carbonic acid has been replaced by the equiv-
alent amount of hvdrochloric acid. This
latter substance, however, is wholly in union
with sodium, as its salt. Thus the addition of
the strong acid diminishes the amount of

152 THE FITNESS OF THE ENVIRONMENT

alkaline salt (sodium bicarbonate), but does
not increase the amount of free acid. Not
until the bicarbonate is entirely decomposed
(318 grams HC1) does the hydrochloric acid
begin to exert its own action as an acid, and
then 2 grams cause about as much rise in
acidity as 318 grams have previously caused,
or nineteen times the rise effected by the first
300 grams, or about two hundred times the
rise caused by one hundred times the quantity
of hydrochloric acid at the beginning of the
experiment.

These statements all rest upon facts which
have been accurately established by experi-
ment and are brought forward in company
with the theoretical treatment, based upon
the Mass Law, only for the sake of complete-
ness of statement and because brief exposition
is otherwise scarcely possible. The extraor-
dinary capacity of carbonic acid to preserve
neutrality in aqueous solution, which is ex-
plained by its strength and solubility in water,
is a well-established experimental fact, and no
other known substance shares this power.1
Hydrogen sulphide might perhaps be thought
of as an exception. But while its solubility

1 Henderson, "The Theory of Neutrality Regulation in
the Animal Organism," American Journal of Physiology, XXI,
427, 1908.

CARBONIC ACID \S$

in water is not favorable for the best resnlu
its instability is a fatal obstacle.

Such are the physico-chemical facts re-
garding neutrality regulation in heterogeneous
systems by means of carbonic acid and bicar-
bonates, and, though the exposition is difficult,
it has seemed necessary to make them clear.
For there is, I believe, except in celestial me-
chanics, no other case of such accuraev in a
natural regulation of the environment. More-
over, the chemist has discovered no means of
rivaling the efficiency and delicacy of adjust-
ment of the process. Finallv, acidity and
alkalinity surpass all other conditions, even
temperature and concentration of reacting
substances, in the influence which they exert
upon many chemical processes.1

Almost wholly through this mechanism the
oceans are always nearly neutral. Chiefly
with its aid protoplasm and blood possess an
unvarying reaction. Quite recently the con-
centration of hydrogen ions in the ocean has
been very carefully studied by Palitzsch,1

1 Of all catalytic agents these ions are by far the moat
important. In their influence upon the stability of collo*
systems they are also unapproached by other Bubstani

2"Etant donne* que l'eau <!•' met a un contact is intime
avec les organismes de la mer <-t que n<>n seulemenl elk V i
entoure de ses flots, mais qu'elle traverse leura branchiei el
impregne en partie Lea corp dea invertebrfe, il seinhle .

154 THE FITNESS OF THE ENVIRONMENT

who finds very great constancy, the extreme
variations (with the exception of the Black
Sea) being 0.000000011 N to 0.0000000045 N.
Allowing for the change of the ionization
constant of water with the temperature, and
the fact that in such systems the hydrogen
ionization is nearly independent of the tem-
perature, these values roughly correspond to
hydroxyl ion concentrations 0.000002 N and
0.000005 N respectively at the lower temper-
atures and slightly higher values at the higher
temperatures of sea water. This is a sufficient
excess of hydroxyl ions properly to be termed
faint alkalinity, though it amounts to but
about 0.00005 gram per liter, or 0.000005 per
cent. It is in part due to the fact that the
quantity of carbonic acid in the air is now
very small, while in the ocean the concentra-
tion of bicarbonates is great. Indeed, the
ocean has unquestionably grown alkaline;

justifie de la placer dans la meme categorie que les autres-
liquides physiologiques. Des determinations exposes dans
ce qui precede il ressort que, de meme que ces liquides, l'eau
de mer est douee d'une grande capacite de regler sa concentra-
tion en ions hydrogene, bien que cette capacite soit moins
prononcee que celle constatee par example dans le sang."
— S. Palitzsch, "Sur le mesurage et la grandeur de la concen-
tration en ions hydrogene de l'eau salee," Comptes-rendus
des travaux du Laboratoire de Carlsberg, lOme Volume,
Ire Livraison, 1911, p. 93.

CARBONIC ACID 155

for its origin must have been acid from the
presence of carbonic acid unbalanced by base.
The present ratio between bicarbonates and
carbonic acid in sea water has not been accu-
rately estimated, but it is perhaps 50 : 1 or
100:1. The conditions are complicated by
flora and fauna, and such influences have not
yet been determined.

Turning to the acid-base equilibrium of
blood and protoplasm, we encounter a subject
which is better understood, though not more
significant in the present discussion. The
alkalinity of the blood is one of the familiar
subjects of physiological investigation, and
its clinical importance has long been clear.
Not until the introduction of the ionization
hypothesis, however, was it possible to explain
the conditions. The outcome of these studies
has been to assign to the equilibrium between
carbonic acid and bicarbonates a first place in
the regulation of the reaction of blood;1 and
since such substances are invariably constitu-
ents of all protoplasm, to make evident the
universal biological importance of this equi-

1 Friedenthal, "Archiv fur Physiologic, Verhandlungen
der Physiologischen Gesellschaft Berlin," May 8, 1908. Hen-
derson, American Journal of Physiology, XV, 457, 190G,
"Ergebnisse der Physiologie," VIII, 454-345, 1909 (the last
a review of the equilibrium between acids and bases in the
organism).

156 THE FITNESS OF THE ENVIRONMENT

librium. The process is complicated by the
intervention of all the other acids and bases
of the body. Of these, however, only phos-
phates, and in lesser degree proteins, are im-
portant. Thus it is certain that in the one
universal chemical equilibrium of protoplasm
which has thus far been defined and quantita-
tively described the carbonates take a prin-
cipal part.

It is not possible to explain the significance
of carbonic acid in this physiological process
as chiefly an adaptation ; for natural selection
can have nothing to do with the occurrence of
carbonic acid in the living organism, or, pre-
sumably, with the nature of the original
living things upon the earth.1 The presence
of carbonic acid is inevitable, and whatever
the first forms of terrestrial life may have
been, certain it is that carbonic acid was one
of the constituent substances. From that day
to this it has steadily fulfilled the function of
regulating the reaction of protoplasm, and of
body tissues and fluids.

The recent studies of Hasselbach and Lunds-
gaard2 indicate that the hydrogen ion concen-
tration of normal blood at body temperature

1 It was this obvious fact which originally led me to a re-
consideration of fitness.

2 " Biochemische Zeitschrift, Vol. 38, p. 77, 1912.

CARBONIC ACID 157

is about 0.000000044 N. This value is sub-
ject to constant slight variations, diminish-
ing as the blood passes through the lungs,
increasing during the greater circulation; but

variations of this kind arc certainly very
slight in the healthy organism. The value
corresponds to a concentration of bicarbonatcs
about ten times as great as that of free car-
bonic acid. Together the acid and its salts
make up the larger part of all the carbonic
acid, and a very considerable fraction of all
the dissolved molecules of the blood. In
disease, especially diabetic coma, the hydro-
gen ion concentration may rise to 0.0000001 N,
or perhaps higher ; when acid is injected into
the blood the value may be greater still, but
death speedily ensues, and it is certainly im-
possible during life that there should be any
considerable permanent variation.

Increase in acidity of the blood can occur
only in association with marked diminution
in the concentration of bicarbonates, which
may fall to less than one third of their normal
amount, greatly impoverishing the blood in
respect to carbonic acid, and interfering with
its excretion. This is due to the fact that
the amount of free carbonic acid in the blood
is under the independent control of the respira-
tory center, and when acids decompose bicar-

158 THE FITNESS OF THE ENVIRONMENT

bonates the carbonic acid which is liberated
escapes through the lungs into the air. This
action is analogous to the simple heterogeneous
equilibrium explained above, and calls for no
special discussion.

The importance of this physiological equi
librium is to be sought in part in one of
the primary characteristics of the metabolic
process, — the chiefly oxidative formation of
acid. In the main the foodstuffs are neutral
substances, but their principal end products,
except water, are almost exclusively acid
compounds, — carbonic acid, phosphoric acid,
sulphuric acid, uric acid. Moreover, there
is a well marked tendency, at least in man and
the vertebrates, under very many pathological
conditions, to form other acids, such as lactic
acid, /3-oxy butyric acid, acetoacetic acid, etc.
This tendency toward acidity of reaction and
the accumulation of acid in the body is one
of the inevitable characteristics of metabo-
lism ; the constant resistance of the organism
one of the fundamental regulatory processes.
Now it comes about through the carbonate
equilibrium that the stronger acids, as soon as
they are formed, and wherever they are
formed, normally find an ample supply of
bicarbonates at their disposal, and accordingly
react as follows : —

CARBONIC ACID 159

HA + NaHC03 = NaA + II2C03

This reaction corresponds exactly to the
simple case first discussed, and so causes an
inconsiderable change in the concentration of
ionized hydrogen. The free carbonic acid
then passes out through the lungs, and the
salt is excreted in the urine. Other processes
are involved, including a device for final re-
tention of a part of the alkali which has neutral-
ized acid,1 but in the whole complex function
nothing is more important than the simple
reaction written above.

The hydrogen ion concentration exerts a
marked influence upon the rate of progress
of chemical reactions. Thus, for example,
the so-called inversion of cane sugar by a proc-
ess of hydrolytic cleavage into glucose and
fructose,

C12H22OH + H20 = C6H1206 + C6H1206,

is commonly accomplished by warming a solu-
tion of sugar to which a little acid has been
added. It was shown by the classical investi-
gation of Wilhelmi that the velocity of this
process depends upon the strength of the
acid, or, according to the modern view, upon

1 Henderson, Journal of Biological Chemistry, IX, 403,
1911.

160 THE FITNESS OF THE ENVIRONMENT

the concentration of hydrogen ions. Indeed,
these ions are the effective agents in the
process.

Reactions of this type, in which carbohy-
drates, fats, proteins, and other substances
take part, make up a very large, if not the
largest fraction of all the processes of metabo-
lism, and there can be no doubt that for their
regulation very accurate adjustment of acidity
and alkalinity is essential. In the body, to
be sure, such reactions are under the control of
enzymes, but the concentration of hydrogen
and hydroxyl ions is not less, rather more
important for that reason. Beside retaining
their direct influence upon the reaction, the
ions also exert an influence upon the enzymes
themselves. Moreover, not only enzymes, but
almost all colloidal bodies, especially such
unstable structures as the colloids of proto-
plasm, are profoundly affected by changes of
reaction, and for the preservation of their
stability they also are absolutely dependent
upon constancy of acidity and alkalinity.

Finally, it is to be noted that glucose, which
is the principal source of energy in physiolog-
ical processes, is very unstable in even faintly
alkaline solutions, and that its stability varies
in most marked degree with the slightest
change in the concentration of hydroxyl

CARBONIC ACID 1G1

ions.1 Further, there is also reason to be-
lieve that the concentration of hydrogen and
hydroxyl ions may sometimes be concerned
in adjustments of great magnitude, which

involve the distribution of water between the
tissues and the body fluids, or at least be-
tween red blood corpuscles and the plasma. -
Recently, for example, a theory has been sug-
gested which seeks to account for certain
forms of oedema as the result of local or general
increase in the acidity of the organism.3
In any case, whatever the fate of these latter

1 Henderson, Journal of Biological Chemistry, X, 3, 1911.

2 The changing distribution of material between red
blood corpuscles and plasma as the tension of carbonic acid
changes has, since its discovery by Zuntz, been investigated
by a series of physiologists. (See Spiro and Henderson,
Biochemische Zeitschrift, 15, 114, 1908.) In each complete
cycle of the circulation there occurs a complete cycle of changes
between the constituents of the corpuscles and of the plasma.
As the blood passes through the tissues and receives carbonic
acid the volume of the red corpuscles increases from tin-
entrance of water coming from the plasma; chlorine simul-
taneously passes in the same direction; and various other
changes occur. In the lungs, with the escape of carbonic
acid, the process is reversed. There seems t<» be DO doubt
that this process is largely dependent upon changes in re-
action accompanying changes in the concentration of carbonic
acid.

3 M. H. Fischer, "(Edema." New York, 1910. It is impos-
sible to judge of the correctness of many of the views set
forth in this work. At present they appear to be in part ill-
founded.

M

162 THE FITNESS OF THE ENVIRONMENT

views may be, the common physiological
processes, and the structural conditions which
depend for their integrity upon constancy of
the concentration of hydrogen and hydroxyl
ions are certainly manifold.

y The principal conditions and processes,
both inorganic and organic, which rest upon
the acid nature of carbonic acid and its char-
acteristic distribution between the atmos-
phere and aqueous solutions have now been
indicated. In their origin at least they are
nowise due to the agency of organic evolution.
Yet directly, because of the nature of carbon
dioxide as a gas, because of its solubility in
water, and on account of the precise degree
of its weakness as an acid, they possess the
highest possible efficiency. This conclusion
might be established with rigorous accuracy
by means of a mathematical analysis, but the
above discussion is sufficient for the present
purpose.1

In this manner carbonic acid shows itself
in its physico-chemical traits variously fitted
for the organic mechanism. Less various, to
be sure, and less obvious than those of water,
such fitnesses as it does possess are quite as

1 Henderson, American Journal of Physiology, XXI, 173,
1908.

CARBONIC ACID 163

genuine. But they arc dependent upon water;
secondary in their nature; resting upon solu-
bility and ionization; upon interactions be-
tween the two substances. So they lead us
to a consideration of the most intricate of
all mutual relations, to a purely chemical
study of the compounds of carbon, hydrogen,
and oxygen, into which water and carbonic
acid can be transformed.

CHAPTER V

THE OCEAN

AT every stage of our inquiry we have seen
that the unique properties of water and
carbonic acid contribute vitally important
characteristics to the ocean. Such conclusions
accord with the ordinary experiences of life,
and they gain in significance from the un-
doubted fact that organic beings first existed,
and for a very long time existed only in the
waters. On this account it will be well to pause
before attacking the problems of organic
chemistry, and, in somewhat greater detail,
to examine the ocean in its relation to the
inhabitants of the globe. Thus we shall be
able more clearly to perceive the manner in
which, in one most important instance, the
properties of water and carbonic acid operate
to fit the world for life.

THE REGULATION OF PHYSICO-CHEMICAL

CONDITIONS

The most striking of all the ocean's qualities
is its constancy. No doubt since its origin

164

THE OCEAN

1G5

it has grown colder and more saline, and has
changed its reaction from faintly acid to
faintly alkaline. But a million years are little
in such great slow processes, and no living
thing has ever experienced appreciable change
in any one of them.

Modern research in oceanography has de-
tected surprisingly little variation in the tem-
perature of the ocean.1 The temperature of
surface water depends upon the climatic
character of the locality, but it is subject to
far less variation than the temperature of the
atmosphere above it, and is higher than the
latter. The accompanying tables 2 indicate
the nature of some of the variations in the
temperature of sea water.

Annual Ranges of Temperatures of Ocean Water
and of the alr over land

0°

10°

20°

30°

40°

50°

2.3

2.4

3.6

5.9

7.5

5.6

—

3.3

7.2

10.2

14.0

25.4

1 Nearly all the facts contained in the present chapter have
been drawn from the following works: S. Giinther, "Hand-
buch der Geophysik " ; Arrhenius, "Kosmische Physik " ; and
Hann's "Climatology," translated by Ward.

2 See Hann's "Climatology," translated by Ward, p.
135.

166 THE FITNESS OF THE ENVIRONMENT

Water and Air Temperatures at Lesina

Winter

Spring

Summer

Autumn

Year

Range

Surface water .
Water at 10 meters

9.2°
13.5
13.9

14.8°

15.0

14.7

24.4°

22.0

20.3

17.9°

19.5

18.4

1G.6°

17.5

1G.8

15.2°
8.5
6.4

According to Schott the variation of surface
temperature of the open ocean over the whole
globe is never less than 1° nor more than 15°.
Such variations are slight on the equator,
larger in the region of the trade winds, less
again in the northern and southern seas.1
The surface temperature extends only a short
distance into the water, thus constituting a
warm surface layer. It has indeed been
known since the time of Aristotle that the
depths of the sea are cold. In the open
ocean the temperature increases steadily as
the depth increases, but more rapidly near
the surface, more slowly at greater depths.
The bottom water at great depth varies from
a temperature of 2° in the tropics to about
— 2° in the polar waters. Such low temperature
of the depths of the tropical oceans is almost
certainly due to the inflow of cold water from
high latitudes.

1 Arrhenius, I.e.

THE OCEAN 167

In the Atlantic the temperature varies ap-
proximately as follows with increasing depth: —

Depth in Meters

Temperature Centigrade

0

19°

500

16

1000

9

1500

4

2000

3

2500

2.5

3000

2

In the Mediterranean, where no cold cur-
rent flows in at the bottom of the ocean, the
temperature sinks rapidly to 11° at a short
distance below the surface, and thereafter re-
mains constant. This is due to the fact that
in winter the surface water is cooled to that
temperature and sinks, remaining then pro-
tected from the summer heat by the warmer
layer of less density above.

The slight range of ocean temperatures,
whether with changing seasons, with chang-
ing depth, or with changing latitude, depends
primarily upon the latent heat of water,
especially its heat of vaporization, and upon
the very high freezing point, as already ex-
plained in the discussion of these physical
properties.

Far more constant than the temperature is
the alkalinity of sea water. It has been stated
above that the extreme variation in concent ra-

168 THE FITNESS OF THE ENVIRONMENT

tion of ionized hydrogen is from 0.00000001 IN
to 0.0000000045 N. In his studies during a
voyage of five months in the summer season
of 1910 of the Danish steamship Thor, Palitzsch
made the following observations: l surface
water from the Skager-Raek, from the south-
ern portions of the North Sea, and from the
west of the Baltic ranged from about
0.000000010 N to about 0.000000009 N ; in the
North Sea the surface water varied from
0.0000000083 N to 0.0000000074 N; at the lati-
tude of Murray Firth, twenty miles from the
coast, the values were between 0.0000000071 N
and 0.0000000066 N. In the Atlantic the
surface water corresponded in the most north-
ern portions to that of the North Sea, while in
the Bay of Biscay and along the coast of
Portugal the values were 0.0000000056 N,
corresponding to slightly increased alkalinity,
especially if account be taken of the rising
temperature. In general the waters of the
Mediterranean corresponded to those of the
coast of Portugal. But from the Sea of Mar-
mora, the Bosphorus, and the Black Sea
samples were obtained which gave the value
0.0000000045 N.

In general, as the depth increased, the

Palitzsch, " Comptes-rendus des travaux du Laboratoire
dc Carlsberg" lOme Volume, p. 85, 1911.

THE OCEAN

169

hydrogen ion concentration increased, and
the alkalinity accordingly diminished.

Depth in

+
(H) x 100,000,000

Meters

Mediterranean

Atlantic

North Sea

Black Sea

0

0.59

0.G0

0.74

0.46

10

0.56

25

0.65

50

0.59

0.66

0.71

75

0.93

85

1.03

100

0.62

0.74

0.81

1.38

200

0.65

0.83

2.1

300

2.8

400

0.65

0.91

0.93

3.0

600

0.98

700

1.05

800

0.68

0.98

1000

0.72

0.98

1200

0.72

1.05

1500

0.76

1.13

2000

0.81

1.13

2500

0.85

3200

0.85

The only variation from the truly remark-
able constancy of reaction of the ocean, so
far as we know, is in the case of the Black Sea.
But this sea, at depths below 180 meters, con-
tains sulphurous acid, which undoubtedly
accounts for the slight diminution of alkalin-
ity recorded in the table. This last obser-

170 THE FITNESS OF THE ENVIRONMENT

vation also provides a striking example of
the efficiency with which the reaction of sea
water is maintained. In spite of the unusual
circumstances here the variation is inconsider-
able. The only known important factor which
operates to establish and to preserve the re-
action of sea water is the carbonate equilib-
rium.

There is one consideration which must be
especially noted before passing on. The most
obvious effect of slight changes of temperature,
and of slight changes of alkalinity as well,
is upon the velocity of chemical reactions.
In this respect the effect of hydroxyl ions is
likely to be in proportion to their concentra-
tion,1 and the effect of temperature is usually
such that a change of about ten degrees doubles
the velocity of the reaction.2 Hence ordinary
chemical reactions will progress about eight
times as fast in the hottest as in the coldest
ocean waters, and about seven times as fast
in the most alkaline as in the least alkaline
parts of the ocean. But in the case of any
organism inhabiting a particular locality such
changes in reaction velocity will be scarcely

1 The chief actions of hydroxyl ions are catalytic, and, as
in the case of the catalysis of esterification, the effect is pro-
portional to the concentration of the hydroxyl ions.

2 This observation is due to van't Hoff.

THE OCEAN

171

appreciable. Accordingly, the regulation is
physiologically adequate.

The concentration of sea water is another
nearly constant characteristic, though gener-
ally speaking the salinity is somewhat greater
on the high seas than near the coasts, where
fresh water is constantly diluting the salt
water, and there are some other causes which
produce slight variations. The average salt
content is about 3.45 per cent. The quan-
tities of the more important constituents,
calculated from Dittmar's data,1 are as fol-
lows : —

Sodium, Na .
Magnesium, Mg
Calcium, Ca .
Potassium, K
Chlorine, CI .
Sulphate, SO<
Carbonate, CO3
Bromine, Br .

Per Cent

1.049
0.130
0.041
0.038
1.89G
0.263
0.007
0.006

Relative Amount

30.59
3.79
1.20
1.11

55.27
7.66
0.21
0.19

Most of the other numerous constituents are
present in very small quantities. For in-
stance, in each metric ton of sea water there

1 Dittmar, Report of Voyage of the Challenger, 1884, p.
203. The original data were calculated upon the erroneous
assumption that the various salts exist in solution independ-

172 THE FITNESS OF THE ENVIRONMENT

are dissolved about 0.019 gram of silver and
about 0.006 gram of gold, amounts which
correspond to 0.0000019 per cent and
0.0000006 per cent, respectively.

It has been calculated that 166,000,000
years have been required for the streams to
carry into the sea the sodium chloride which
is now present. The calcium carbonate of
the rivers wTould however suffice to supply
the present amount of that substance in 500,-
000 years. Accordingly, the present store of
the latter substance represents but a very
small fraction of what has passed through the
ocean, and as a result of the intervention of
life has finally been deposited as sedimentary
limestone. Since the formation of the ocean,
if present conditions correspond with the past,
water must have carried to the dwellers of

ently of one another. Thus the composition of sea water is
stated as follows : —

Sodium chloride, NaCl
Magnesium chloride, MgCU .
Magnesium sulphate, MgS04
Calcium sulphate, CaS04
Potassium sulphate, K2S04 .
Calcium carbonate, CaC03 .
Magnesium bromide, MgBr2

Relative
Amount

77.758
10.878
4.737
3.600
2.465
0.345
0.217

THE OCEAN 173

the sea not less than 300,000,000,000,000,000
tons of calcium carbonate, which they have
temporarily utilized as structural material.
Whether this estimate be correct or not, the
process is certainly the cause of the most
considerable change wrought by life upon the
face of the earth.

The relative quantities of the several saline
constituents of the ocean are hardly at all
subject to variation. Chlorine, for example,
makes up never less than 55.21 per cent and
never more than 55.34 per cent of all the dis-
solved inorganic substances, so that the total
salinity may be readily estimated with consid-
erable accuracy by titration of the chlorides.
Such constancy is due to the elaborate mixing
of the waters resulting from ocean currents.
There can be no doubt, however, that the
relative amounts of the different acids and
bases have slowly but steadily changed during
the progress of geological evolution. Many
substances, like calcium carbonate, have been
steadily removed, a few, like sodium chloride,
have steadily accumulated without loss.

The total salinity of the ocean, as stated
above, is subject to slight variation. Along
the North American coast, in the polar cur-
rent, upon the coast of Norway, and toward
the south of South America, the concentration

174 THE FITNESS OF THE ENVIRONMENT

of the Atlantic is 3.2 per cent to 3.3 per cent.
Areas where the concentration ranges from
3.3 per cent to 3.4 per cent are still more
extensive. The greater part of the North
Atlantic ranges in concentration from 3.5
per cent to 3.6 per cent. In general there is a
region of maximum concentration between the
Equator and the Pole.

The Mediterranean, the Red Sea, and other
similar bodies of water possess a somewhat
higher salt concentration, dependent upon
excessive evaporation and the absence of
great currents ; but only in exceptional cases
and small isolated bodies of water does the
concentration rise above 4.1 per cent.

The salinity of ocean water varies also with
the depth. In seas where there is a great
influx of fresh water the surface is less con-
centrated than the depths; in seas where
there is much evaporation the surface is more
concentrated than the depths. In the latter
case the higher temperature of the surface
causes expansion of the more concentrated
water, and enables it to remain above. When
these two influences of dilution and evapora-
tion are combined, they may bring about a
yearly variation of salinity. Such variations
of the environment are important to animal
life, slight though they may be. Thus the

THE OCEAN 175

herring in their migrations keep to a water
whose concentration ranges from 3.2 per
cent to 3.3 per cent.

From the constancy of the relative pro-
portion of the salts in sea water it follows that
every such constituent is subject to no greater
variations than the sum of all. Interesting
recent experiments have shown this fact to
be of vital consequence to living organisms.
Thus a host of experiments of Loeb and his
pupils, and of others, have demonstrated re-
markable toxicity in the action of pure salts,
physiologically antagonistic actions of vari-
ous pairs of salts, and peculiar advantages of
media containing a variety of salts in definite
relative amounts.1 Of all such balanced solu-
tions sea water is by far the best, a condition
which is almost certainly due to the processes
of organic evolution. Herbst 2 has shown
that the development of the fertilized eggs
of sea urchins can only take place in the
presence of the chlorides, sulphates, and car-
bonates of sodium, potassium, calcium, and
magnesium, and in a faintly alkaline reaction.
Every one of these substances is essential,

1 See the article by Loeb in Oppenheimer's "Handbuch
der Biochemie."

2 Herbst, Archiv.fiir Ejitwickelungsmechanik, 5, 050, 1897;
7, 486, 1898; 11, 617, 1901; 17, 300, 1904.

176 THE FITNESS OF THE ENVIRONMENT

except that in a measure potassium may be
replaced by rubidium and caesium, and chlo-
rine by bromine. Moreover the relative con-
centrations are of the highest importance.
Thus it has become clear that the remark-
able relative and absolute constancy of the
chemical composition of sea water is biolog-
ically far more important than formerly
could be surmised. This characteristic of
the ocean undoubtedly fits it for living
things as they exist.

It is further to be noted that the salinity of
sea water is proportional to its osmotic pres-
sure. This important property also is there-
fore nearly constant.

When a solution is inclosed in a membrane,
a bladder, for example, and the latter is im-
mersed in water, both water and dissolved
substance pass through the wall of the mem-
brane. Ordinarily, however, the water will
move much more rapidly than the dissolved
substance, hence the volume of the solution
will increase, and hydrostatic pressure will
be established. If a well-supported mem-
brane of cupric ferrocyanide be substituted
for the bladder, the process will be modified,
in that water alone, not the dissolved sub-
stance, can pass through the membrane,
which is accordingly termed semipermeable.

THE OCEAN 177

Under these circumstances the pressure, called
osmotic pressure by van't Hoff, may be very
great.

According to the theories of van't Hoff
and Arrhenius this pressure is, in the case of
dilute solutions, proportional to the total
number of particles (molecules plus ions)
which are present in solution. In its magni-
tude and the laws governing its variation such
pressure corresponds exactly to gaseous pres-
sure. In fact the theory of solution consists
primarily in the extension of the laws of Boyle
and Gay-Lussac, of the hypothesis of Avo-
gadro, and of the manifold theoretical develop-
ments which have been based upon them, to
solutions. The great force of osmotic pres-
sure always comes into action when solutions
are in contact with permeable or semiper-
meable membranes. It must therefore al-
ways be reckoned with in physiology. The
biological importance of the constancy of the
osmotic pressure of sea water is strikingly
exemplified by the precision with which every
higher vertebrate preserves constant the os-
motic pressure of its own body fluids, all at
about seven or eight atmospheres.

It may readily be shown that the osmotic
pressure of a solution is proportional to the
depression of its freezing point, and accord-

178 THE FITNESS OF THE ENVIRONMENT

ingly osmotic pressure is commonly estimated
with the help of this relationship. In the
following table the facts regarding blood sera
of certain animals are collected.1

Depression of the Freezing Point of Blood Serum

Degree

Man 0.526

Cow 0.585

Horse 0.564

Pig 0.615

Rabbit 0.592

Dog 0.571

Cat 0.638

Sheep 0.619

In man the freezing point depression of the
blood is, under ordinary circumstances, practi-
cally constant, and there can be no doubt that
such is the case for all highest organisms.
Accordingly the differences in the above table
may be taken to indicate slight constant dif-
ferences between the different species.

The marine animals, except a few of the
vertebrates, are adjusted in their osmotic
pressures to the water which surrounds them.
As in the following table so in another lo-
cality where the freezing point of the water
was —1.9° the bodv fluids of the animal
were again found to agree with it. It is
therefore evident that constancy of osmotic

1 Hober, " Physikalische Chemie der Zelle und der Gewebe."

1
a

<
M

u

•<

-
-
-

E

«

THE OCEAN 179

pressure is for marine animals a matter of
real moment.

Depressions of the Freezing Point

Degrees

Calentratc, Alcyonium palmafum. 2.196

Echinodcrm, Astcropcctcn aurantiacus 2.312

Echinodcrm, Flolotluiriu lubulosa 2.315

Worm, Sipuneuhu nudus 2.31

Crustacean, Maja squinada 2.3G

Crustacean, Homarus vulgaris 2.29

Cephalopod, Octopus macropus 2.24

Selachian, Torpedo marmorata 2.26

Selachian, Mustelus vulgaris 2.36

Selachian, Trygon violacea 2.44

Teleost, Charax puntazzo 1.04

Teleost, Cerna gigas 1.035

Teleost, Crenilabrus pavo 0.74-0.76

Teleost, Box salpa 0.82-0.88

Reptile, Thalassochelys caretta 0.61

Sea Water 2.3

The great importance of osmotic pressure
is also attested by many of the facts of phys-
iology. The study of this subject has in-
deed from its origin always been closely
associated with the biological sciences, and it
was in great part biological experiments and
wholly experiments of biologists which were
employed by van't Hoff in his development,
on the basis of osmotic phenomena, of the
theory and laws of dilute solutions.

Absorption, secretion, excretion, and the
movement of substances across membranes,

180 THE FITNESS OF THE ENVIRONMENT

— to say nothing of the establishment of
liquid currents within the body, — are all
related to osmotic pressure. The forces in-
volved in such processes are large, and osmotic
phenomena assume a special importance
wherever colloidal systems occur. It appears
to be certain that osmotic pressure is now se-
curely established as one of the fundamental
factors in the physico-chemical organization of
the living mechanism, and one of the constant
conditions, like concentration of the several
constituents, alkalinity, temperature, etc.,
whose preservation is of vital importance.

n

THE CIRCULATION OF WATER

There are a number of causes which bring
about ocean currents. In the tropics high
temperature causes a far greater evaporation
of water than can be offset by rainfall and the
flow of rivers ; near the poles this relation is
reversed. Hence water must steadily flow
from high to low latitudes, there to evaporate
and complete the cycle in the atmosphere and
on the land. In polar regions the cold water
sinks and penetrates along the bottom of the
sea in great deep currents to the tropics.

THE OCEAN 181

The surface currents of the ocean have a
different origin, for they depend upon winds,
especially trade winds, etc. Such continuous
action of moving air upon water has been
theoretically explained by Ilelmholtz and
Zopperitz. Needless to say, in addition to
these principal causes there are a great variety
of lesser factors which assist in the formation
and preservation of ocean currents.

It is impossible here to undertake an analy-
sis of the phenomenon, but certain it is that
into the processes that constantly stir the
ocean, beside the rotation of the earth, the
eccentricity of its orbit, and the inclination of
its axis, the thermal properties of water enter
as fundamentally important factors.

The magnitude and the extent of the
movements which result from such influences
are very considerable. The principal surface
currents are oval in form, one in the North
Pacific between 10° and 50° north latitude,
one in the North Atlantic between 10° and
30° north latitude, one in the South Pacific
between 5° and 45° south latitude, one in the
South Atlantic between 0° and 40° south
latitude, and one in the Indian Ocean between
0° and 40° south latitude. The greatest of
these are the Pacific currents. In the far
south is an Antarctic current flowing from

182 THE FITXESS OF THE ENVIRONMENT

west to east ; in the north a current flows
from east to west, from the Siberian coast
to Northeast Greenland and thence along the
east coast ; another flows from Baffin's Bay
along the east coast of North America.

Of all ocean currents, the Gulf Stream, a
branch of the northern equatorial current,
has been most carefully studied. Its maxi-
mum velocity is 220 kilometers per day,
greater therefore than that of the Rhine at
Coblentz ; the mean about 134 kilometers a
day. In the Straits of Yucatan the Gulf
Stream carries 0.2 cubic kilometer (200,000,-
000 tons) per second. If all this water were
to be cooled to the temperature of the polar
ocean this would be equivalent to the trans-
port of about 5,000,000,000,000,000 gram
calories per second. The magnitude of this
quantity, of course, depends upon the specific
heat of water.

In this manner vast quantities of water,
carrying enormous stores of heat, are constantly
in motion all over the globe. The result is
that homogeneity of the ocean which has been
discussed above, — constancy of concentra-
tion, of composition, of temperature, of alka-
linity, and of osmotic pressure.

THE OCEAN 183

III
THE OCEAN AS ENVIRONMENT

There are, in accordance with our funda-
mental postulates of the characteristics of
life, two principal requirements of the living
organism which an environment must ful-
fill, — such a supply of matter and energy
for food as may be suitable to a complex
mechanism, and stability of conditions.

After a general review of the chief character-
istics of the ocean, it is therefore necessary to
examine them more particularly in relation to
such requirements. In so doing it must not
be forgotten, however, that these characteristics
of the ocean which we have just discussed are
only in part due to the unique physical proper-
ties of water which have been alreadv dis-
cussed in Chapter III, and to those of carbonic
acid which have been discussed in Chapter
IV. In part they depend upon the mere
magnitude of the sea, on the stability of the
solar system and the consequent antiquity of
the geological and meteorological processes,
and upon a great variety of astronomical and
geophysical conditions. However, we shall
only a little extend the scope of our inquiry
if we now consider water not only as an indi-

184 THE FITNESS OF THE ENVIRONMENT

vidual chemical substance, that is to say ab-
stractly, but also naturally, as automatic
processes of cosmic and geological evolution
have fashioned it into the principal constit-
uent of the face of the globe. Primarily,
at any rate, the outcome of such processes is
dependent upon the inherent properties of
water and upon the quantity of it which is
present on the surface of the earth, and the
subject is too important to be passed com-
pletely by.

Perhaps the first desideratum in an en-
vironment as a source of food is mobility.
Any organism which, like the lilies of the field,
need not toil for its nourishment, is in most
favorable conditions, and such conditions
are the principal cause of the enormous wealth
of vegetation upon the earth. Now the ocean,
apart from the flora and fauna which inhabit it,
is perfectly homogeneous ; hence its mobility
brings to an organism all that it has to offer,
and even sweeps along organic nourishment
as well. In the ocean not only plants but
many animals may remain motionless and,
like the oyster, await the food that will surely
be borne to them ; or they may float freely,
relying on the mixing of the water to bring
them into contact with their food.

After mobility, richness and variety of

THE OCEAN 185

environment are important. It is certainly
impossible to imagine a medium more rich and
varied in elementary constituents than sea
water, unless it be sea water with still other sub-
stances added to it. But, in the first place,
there are few absent elements which might
be added, and, in the second place, the addition
of other substances would be likely to cause
the escape of bodies which are present. At
all events, the ocean is certainly more favor-
able in these three respects than if it were
anything else that could occur in the course
of nature. Almost ideally mobile, rich, and
varied, the sea is an almost perfect source of
supply for a complex mechanism. To be
sure there are great difficulties in extracting
its constituents from sea water, and the
efficiency of physiological processes is a factor
essential to their utilization, but at least
there stand materials ready for the mechanism
which can employ them.

The predominance of water, no doubt, forces
that substance upon living beings as their
chief constituent; in view of the fitness of
water for the purpose that is in itself a favor-
able circumstance. Otherwise the organism
is left free to choose from all the common
elements, and from some of the rare ones, what
may be most suitable to its purposes at every

186 THE FITNESS OF THE ENVIRONMENT

stage of the infinitely varied process of organic
evolution. As a result we find here and there
in the marine flora and fauna almost every
element which the sea affords concentrated
and put to use.

After what has gone before it will not be
necessary further to discuss the second great
qualification of an environment — stability
of conditions in the ocean. The principal
physical conditions and chemical compounds
therein are constant ; that is the whole case.
But it is a case which cannot be bettered.
Certainly nowhere else where life is possible,
probably in no other place in the universe
except another ocean, are so many conditions
so stable and so enduring.

The regulatory devices of our modern labo-
ratories have not yet succeeded in rivaling
the ocean. Singly, certain conditions, for
example, temperature, alkalinity, and concen-
tration, may be more accurately regulated by
man, though on a small scale only ; but the
regulation of all such properties together is
not yet possible. The only known improve-
ment upon the ocean is the body of a higher
warm-blooded animal. Here, however, the
processes of organic evolution have begun
with the ocean, and in several respects merely
perfected existing arrangements.

THE OCEAN

187

This statement is far from fanciful. Not
only do the body fluids of the lower forms of
marine life correspond exactly with sea water
in their composition, but there are at least
strong indications that the fluids of the highest
animals are really descended from sea water,
from the sea water of an earlier epoch, to be
sure, and they are not changed beyond recog-
nition by the transformations of evolution.1
A comparison of the relative amounts of
various saline constituents in sea water and
in mammalian blood (roughly averaged from
a variety of measurements in different species)
will demonstrate this relationship.

Composition of the Salts in Per Cent

Sea Water

Blood Serum

Na

30.59
3.79
1.20
1.11

55.27
7.66
0.21
0.19

39

Mg

Ca

0.4
1

K

2.7

CI

45

S04

C03

12

Br

P,Os

0.4

1 See the interesting paper by Macallum, Transactions of
the Royal Society of Canada, 1908, II, p. 145.

188 THE FITNESS OF THE ENVIRONMENT

The gaps in the table do not indicate that
substances are lacking, but merely that the
amounts are small. In short, the same sub-
stances are present in both cases, and in both
cases sodium chloride largely predominates.
The importance of carbonic acid in metabo-
lism accounts for the large amount of sodium
bicarbonate in the blood, and this raises the
amounts of both sodium and carbonic acid.

It is also to be noted that the regulatory
processes in the ocean and in the organism
are in one or two aspects similar, e.g. tempera-
ture regulation by evaporation, and regula-
tion of the alkalinity. Of course no impor-
tance attaches to such resemblances, beyond
the fact that both regulations are highly
favorable, because of the special fitness of
water in one case and of carbonic acid in the
other. But it is at least worthy of mention
that the regulation of the ocean in general
bears a striking resemblance to a physiolog-
ical regulatory process, although such physi-
ological processes are supposed to be the
result of organic evolution alone. Very much
this same idea occurred to Palitzsch in the
course of his investigation of the alkalinity
of the ocean.1 The resemblance is more ob-
vious still when the stability of all the more

1 See note above, p. 153.

THE OCEAN 189

important physical conditions of the ocean is
taken into account. Indeed, however difficult
it may be to make out those subtle traits of
physiological processes which account for
their efficiency, their adaptability, and their
exactness, I feel sure that no one who is thor-
oughly conversant with the general char-
acteristics of the life process can fail to see a
rough counterpart in the means by which
conditions in the ocean are regulated.

It is certainly a salient, and hardly a mean-
ingless fact that the processes of inorganic
and organic evolution have a similar out-
come in complex, exact, and almost ideally
efficient activities. Is it not possible that in
the case of the organic processes some have
now and then been regarded as adaptations
which in reality arose automatically and
quite inevitably ?

The existence of efficient regulation of the
ocean, establishing its most important physico-
chemical characteristics as constants, is of
far greater importance in the sciences of nature,
especially for living organisms, than could
formerly have been guessed. Such natural
processes were perhaps even necessary to
make life possible in the birthplace of life. I
cannot undertake to explain the very great
importance which to-day the physical chemist

190 THE FITNESS OF THE ENVIRONMENT

attaches to the regulation of the conditions of a
chemical process. The only way to gain an
idea of this is to examine a work on physi-
cal chemistry. Certainly, however, nothing has
lately arisen more essential to biology than the
understanding of the influence of temperature,
pressure, reaction, concentration, ionization,
etc., upon all physico-chemical structures
and changes, whether inorganic or vital.

Thus the fitness of the ocean appears as an
embodiment of the physical fitnesses of water
and carbonic acid, resulting directly and in-
evitably from these and other natural phenom-
ena, and providing a lodgment for life and a
medium for its earlier development upon the
earth. No philosopher's or poet's fancy, no
myth of a primitive people has ever exag-
gerated the importance, the usefulness, and
above all the marvelous beneficence of the
ocean for the community of living things.

CHAPTER VI

THE CHEMISTRY OF THE THREE

ELEMENTS

ORGANIC CHEMISTRY

A HUNDRED years ago the firm belief
was held by all chemists that whatever
substance is synthesized within the body of
the living organism possesses special and pe-
culiar characteristics of its own, which mark
it off from all inorganic bodies, and divide
chemistry into the two great and perfectly
distinct departments of Organic Chemistry
and Inorganic Chemistry. To be sure, even
then many organic substances had been sep-
arated from the organism, purified, and sub-
jected to the usual experiments of the labora-
tory, without at any stage manifesting unique
properties. But, as Berzelius believed, a
special vital force had presided over their
formation, and this, therefore, he supposed
to be impossible under any other circum-
stances.

191

192 THE FITNESS OF THE ENVIRONMENT

In the course of time, however, a long series
of successful syntheses of undoubted constitu-
ents of animals and plants, among which Woh-
ler's preparation of urea in 1828 is the most
famous, completely destroyed the old erro-
neous assumption. The compounds of organic
chemistry gradually came to be recognized
as different from inorganic substances only
in the special characteristics of the elements
carbon, hydrogen, and oxygen when in chem-
ical union with one another, just as the com-
pounds of any other elements have their own
specific characteristics. No other difference
remains; every principle of chemical science
applies to organic and inorganic substances
alike; and accordingly life has been for-
ever subjected to the general laws of chem-
istry.

As syntheses multiplied, the organic chem-
ist found many fields for investigation where
life was not concerned. The application of
his new substances in the arts, as well as many
fascinating theoretical problems, led him on,
until, about the middle of the century or a
little later, it became clear that organic sub-
stances in the original sense are but a small
part of his scope. His occupation had be-
come the study of all the compounds of
carbon, wherever and however they might

CHEMISTRY 193

occur, and as a rule he had little to do with
physiological or biological chemistry. Not
that he was now ever disposed to distinguish
between substances which happened to occur
in living organisms and others ; for at length
he had completely accepted the view that,
apart possibly from a few complicated sub-
stances like the proteins, such distinctions
are thoroughly irrational. But the nature of
the subject and the historical accidents of
its development directed his attention in the
main elsewThere.

Nevertheless, the distinction between or-
ganic chemistry as the science of all the com-
pounds of carbon, and inorganic chemistry
as the science of all other chemical compounds
whatever has persisted, and not without
sound reasons. In the course of the wonder-
ful development of organic chemistry, which
must ever be counted as one of the greatest
achievements of the nineteenth century, enor-
mous numbers of new chemical substances
were discovered. In 1883 the number of
carbon compounds had reached 20,000, in
1899, 74,000, and in 1902 it exceeded lOO^OO.1

1 See M. M. Richter, "Lexikon der Kohlenstoffverbindun-
gen," Hamburg and Leipzig, 1900, continued in supplemen-
tary volumes. This work catalogues all the compounds of
carbon as they come to light.
o

194 THE FITNESS OF THE ENVIRONMENT

This is the sufficient practical ground for pre-
serving organic chemistry as a separate sci-
ence. The subject is so vast that in fact it
is impossible to incorporate it with other
departments of chemistry. Even the com-
pounds of carbon and hydrogen alone are
counted by hundreds, those of carbon, hydro-
gen, and oxygen, by thousands, and the
number of possible compounds of the three
elements is almost unlimited.

The mere number of organic compounds is,
however, far from constituting the only dis-
tinction between the two departments of
descriptive chemistry. The unique variety
of compounds containing carbon, hydrogen,
and oxygen, and, in a small proportion of cases
a few other elements besides, must obviously
rest upon the nature of the elements them-
selves, especially of course upon the nature of
carbon, upon the properties which are pe-
culiar to them and which mark them off from
other elements, just as the properties of
argon, of the metals of the alkalies, or of the
halogens determine their own chemical be-
havior. Moreover, such characteristics must
and do contribute properties to the com-
pounds of carbon which are theirs as a class,
which distinguish them from the compounds
of other elements in somewhat the same way

CHEMISTRY 195

that the anatomical characteristics of one
class of animals distinguish such a class from
other classes of animals. In short, the carbon
compounds are not unique merely because
they are numerous; they are uniquely nu-
merous because they are compounds of carbon
with hydrogen, oxygen, and in some cases
certain other elements. They possess, more-
over, other less obvious class properties as
well, though of these, it must be admitted,
chemistry is even yet far from a clear under-
standing. But unquestionably that is due
to the incompleteness of the science, for the
peculiar methods of organic chemistry are a
sufficient guarantee of the existence of such
class peculiarities.1

In our present investigation a study of the
possibilities of chemical union between the
elements carbon, hydrogen, and oxygen is of
great importance, and accordingly we must
now examine some of the results of synthetic
organic chemistry.

1 See the introductory chapter to Meyer and Jacobson's
"Lehrbuch der Organischen Chemic," Leipzig, 1907.

196 THE FITNESS OF THE ENVIRONMENT

VALENCE

The principal theoretical foundation of
organic chemistry is the idea of valence.
Let us consider the chemical formulas of a
number of the simple compounds of hydrogen,
e.g. HC1, H20, NH3, CH4, HI, HBr. It is
evident that in such formulas a single atom of
hydrogen is never represented as in union
with more than one atom of another element.
There are, however, cases where one atom of
hydrogen is in union with a single other atom,
e.g. HC1, HBr, HI ; or two atoms of hydro-
gen may unite with a single other atom, e.g.
H20 ; or three atoms of hydrogen with one
other, e.g. NH3 ; or four hydrogens with one
other, e.g. CH4. If the assumption be made
that discrete bonds or forces take part in the
union of atoms, hydrogen must possess but a
single such bond or valence. Otherwise com-
pounds of the type X — H — X, X — H<Q",or

of some other type in which one atom of
hydrogen is in union with more than one atom
of lower valence, must exist, and this is con-
trary to fact.

We may, therefore, employing a dash to
represent valence, write the constitutional

CHEMISTRY 197

formulas of hydrochloric acid, water, and
methane, as follows : —

h-ci, h-o-h, [!X'<[[

Accordingly, oxygen appears to possess two
valences and carbon four. These conclu-
sions are justified by an almost inconceivable
wealth of experience ; they are the means of
constructing the elaborate constitutional for-
mulas which are so necessary a part of organic
chemistry ; and there can be no doubt that
in almost all the compounds with which we
shall be concerned hydrogen is invariably
univalent, oxygen bivalent, and carbon quad-
rivalent. On this basis the construction of
possible formulas of organic compounds is
merely an exercise in a somewhat peculiar
department of mathematics.

B

HYDROCARBONS

The compounds of carbon and hydrogen

may first be considered. With but a single

atom of carbon in the molecule one only is

possible : —

H

H-C-H

I
H

198 THE FITNESS OF THE ENVIRONMENT

Uniting two carbon atoms by a single valence,
the formula

H H

H-C-C-H

I I

H H

representing the compound ethane is ob-
tained ; but if the process be extended, great
complexity speedily ensues. For example,
the hexanes, compounds formed upon this
plan containing six carbon atoms, all of one
empirical formula, number five. Their con-
stitutions are represented by the accompany-
ing structures, every one of which corre-
sponds to a known substance : —

H H H H

I I I I

H-C-H H-C-H H-C-H H-C-H H

I \^ I I

H-C-H C-H H-C-H H-C-H

H-C-H H-C-H C-H

H-C-H H-C-H H-C-H

I I I

H-C-H H-C-H H-C-H

I I I

H-C-H H H

I
H

CHEMISTRY 199

H H

I I

-C- [-C-]

C-H
I
C-H

H-

I
H

H-C-H

I
H

In each of the compounds represented by
these formulas every carbon atom is believed
to have four valences and every hydrogen
atom one.

As the number of carbon atoms in the mole-
cule increases the number of possible forms,
isomers so called, multiplies with great rapid-
ity. Of compounds C7H16 there are 9 forms;
for C8H18, 18; for C9H20, 35; for C10H22, 75;
for CnH24, 159; for C12H26, 355; for C13H28,
802; and for Ci4H30, 1855 possibilities.1 There
can be no reasonable doubt that the prepara-
tion of each and all of these compounds would
be possible, and that once formed they would
be very stable substances. In truth, no one

1 Cayley, Berichte, 8, 105fi (1875). F. Hermann, Berichte,
13, 792 (1880) ; 30, 2423 (1897) ; 31, 91 (1898). Losanitsrh,
Berichte, 30, 1917, 3059 (1897). "Optical isomers" are dis-
regarded in the estimate.

200 THE FITNESS OF THE ENVIRONMENT

has ever failed who has set out with skill,
a good plan, and suitable starting materials,
to prepare such a body.

The number and variety of hydrocar-
bons is further enormously extended by the
possibility of double and treble unions be-
tween pairs of carbon atoms, as in ethylene,

and acetylene,

H-C^C-H

Further, more than one double or treble
bond, or single, double, and treble bonds in
combination, may occur, as in the well-known
substances CH3 - CH = CH2, CH3 - C ■ CH,
CH2=C = CH2, etc.

Finally, the carbon atoms possess the prop-
erty of uniting to form ring compounds in
great variety, e.g.

H H

CH2 C C

/\ s\ s\

CH2 CH2 HC CH2 HC CH

CH2 CH2 HC CH2 HC CH

\/ v x/

CH2 C C

H H

CHEMISTRY

CII2-CH2

CH2 — CH2

1 1

\/

CH2 CH2

CH2

\y

CH2

201

Moreover, such rings may unite with carbon
chains, both those containing single bonds,
and those containing double and treble bonds,
whether straight or forked, in great variety ;
and also with other rings, e.g.

CH3

ch3

CH,

1

1

1

C

c

C

S\

•\

/\

HC CH

H-C C-

CH3

HC CH

1 II

1 II

»

1 II

HC CH

HC CH

HC C-CH,

V

x/

\/

c

c

C

H

H

H

CH3

CH,

1

H

1

C

C

C

S\

•\

.CH3

X\

HC CH

HC C-CH<

HC CH2

1 II

1 II

CH,

1 1

HC CH

HC CH

HC CH2

V

V

v/

c

c

CH

1

H

1

ch3

c

/X

CH3 CH2

202 THE FITNESS OF THE ENVIRONMENT

H H H H

C C C H C

HC C CH HC C - C - C CH

I II I , I II I I II
HC C CH HC CH H HC CH

\S\S x/ v

c c c c

H H H H

It is quite impossible briefly to indicate,
still less to give an adequate idea of the
bewildering diversity and complexity of the
known hydrocarbons. They exist by the
hundreds, and there are certainly countless
thousands of possible stable bodies made up
of carbon and hydrogen alone.

C

COMPOUNDS OF CARBON, HYDROGEN, AND OXYGEN

With the addition of oxygen, the variety and
number of known and of possible substances
is still further multiplied. Oxygen may enter
into the following types of union with carbon
and hydrogen in organic compounds : —

= C-0-H, eeeC-0-C=, =C=0.

Alone or in combination, these groups yield
a great variety of important classes of com-
pounds. Representing a group or radical
consisting of carbon and hydrogen alone by

CHEMISTRY 203

R, a few of the most simple and important
divisions are as follows : —

Alcohols, primary RCILOH

Alcohols, secondary R2CHOII

Alcohols, tertiary R3COH

Aldehydes R-CHO

Ketones R2CO

Acids RCOOH

Esters RCOOR

Ethers ROR

By the introduction of oxygen into the
molecule any complex hydrocarbon may be
converted into a great number of substances,
and even in simple cases such derivatives
are not few. In the accompanying formulas
I have gathered together the possible hydro-
carbons containing three carbon atoms (ex-
cluding ring compounds), and their possible
oxygen derivatives, most of which are capa-
ble of existence as substances of varying
stability, many of them being in fact well-
known common substances like lactic acid,
glycerine, propionic acid, propyl alcohol, two
of the simplest sugars, etc.

CH3 CH3 CH2 CH3

I I ll I

CH2 CH C C

I II II III

CH3 CH'2 CH2 CH

204 THE FITNESS OF THE ENVIRONMENT

CH3 CH3 CH3 CH3

I I I I

CH2 CHOH CH COH

I I II II

CH2OH CH3 CHOH CH2

CH2OH CH2

I II
CH C

II II
CH2 CHOH

CH3 CH2OH CH3 CH2OH CH3 CH-OH

I I I I I I

C C CHOH CHo COH CH

III III || II II

COH CH CH>OH CH2OH CHOH CHOH

CH2OH

CHOH

II

C
II
CHOH

CH2OH

i

CH2OH

CHoOH

1

COH

II
CH2

i

C
III
COH

CHOH
1
CH2OH

COH

li
CHOH

CH3

1
CH2

1
CHO

CH3

1
CO

1

CH3

CH3

1
CH

II
CO

CHO

1
CH

II
CH2

CO

II

C
II
CH2

CHO

1

c

III

CH

CH3

CHO

CHO

CO

II

c

II

CO

CHO

1

CO
1
CHO

CH2

1
CHO

CH

II
CO

CO

1

CHO

CH3

COOH

COOH

i

COOH

CH2

1
COOH

CH

II
CH2

i

c

III

CH

CH2
1
COOH

CH3

CHoOH

CH2OH

I

CH3

1

CH2OH

1

CHO

1

CHOH

1
CHO

CH2

1
CHO

CO

1

CH3

COH

II
CO

CH

II
CO

COH

II
CH2

CHEMISTRY

205

CHO

I
CH

II
CHOH

CHOH

II

C
II
CO

CHO
I
C

III

COH

CH2OH CH2OH CHoOH CHO CH2OH CHO

I I I I I I

CHOH CO COH COH CO CHOH

I I II II I I

CHO CH2OH CO CHOH CHO CHO

CHO

COH

II
CO

CH3 CH2OH COOH COOH COOH CHoOH

I I I I I I

CHOH CH2 COH CH C CHOH

I I II II III I

COOH COOH CH2

COOH COOH

CHOH COH

COOH

I

COH

II
CHOH

CHOH

COOH

CH3

CHO

1

COOH

1

COOH

CO

CH2

CH

II
CO

CO

COOH

COOH

COOH

CH,OH CHO COOH

I I I

CO CHOH COH

I I II

COOH COOH C = O

206 THE FITNESS OF THE ENVIRONMENT

This is relatively a simple case. As the
number of carbon atoms in the molecule
increases, the number of possible oxygen
derivatives multiplies in a far more rapid
progression than in the case of the simplest
hydrocarbons, which has been stated above.
Accordingly there can be no doubt that in
addition to the many thousands now known,
the existence of countless millions of com-
pounds consisting of carbon, hydrogen, and
oxygen alone is possible. In a large propor-
tion of cases the only difficulties involved in
their preparation are to obtain suitable start-
ing materials, and the enormous labor of the
process. There are, for instance, hundreds
of thousands of possible hydroxyl derivatives
alone of the paraffine hydrocarbons of the
formula Ci4H30, but only one of these is now
known.1 Yet all, or at least a vast majority,
would unquestionably be stable bodies if
once formed.

Not less important than the number and
variety of such substances is their diversity
of physical and chemical characteristics. The
following are, for example, individual chemi-
cal compounds of at least moderate purity,
made up of the three elements alone : al-
cohol, formaldehyde, acetic acid, carbolic

1 Me thai, a constituent of spermaceti.

CHEMISTRY 207

acid, oxalic acid, acetone, ether, lactic acid,
sugar, cotton, glycerine, olive oil, camphor,
tannin, ophiotoxin (the chief poisonous con-
stituent of cobra venom), starch, vanilline
(the flavoring constituent of the vanilla bean),
oil of wintergreen, salol, benzoic acid, digita-
line.

Here is a variety that baffles description ;
but description is hardly necessary, for the
facts explain themselves. In short, the com-
pounds of the three elements which compose
water and carbon dioxide exist in enormous
numbers and in unparalleled diversity of chem-
ical and physical characteristics. They in-
clude substances of the greatest stability, and
others of exceeding instability ; liquids, solids,
and gases ; chemically active and chemically
inert bodies ; acids and neutral substances ;
substances which are readily oxidized and
others which are oxidized only with great
difficulty. In a very large proportion of
cases these compounds are capable of enter-
ing into reactions with one another. They
are, moreover, capable of forming still more
complex substances, in still greater variety
by entering into union with other elements,
notably with nitrogen and sulphur.

208 THE FITNESS OF THE ENVIRONMENT

D

OTHER ORGANIC COMPOUNDS

The organic substances which contain
nitrogen are very numerous and exceedingly
diverse in their properties. A few of the
principal classes of such compounds are the
following : —

Amines R-NH2, R2NH, R3N

Nitrocompounds R — N02
Nitriles R-C = N

Isonitriles R — NC

Amino-acids R-CHNH2COOH

R-N.
Azoxy compounds I /O

R-Nx

Azo compounds R — N = N — R

Hydrazo compounds R — NH — NH — R

Derivatives of purine, pyridine, and other
ring systems, etc.

The nitrogenous organic substances include
classes of compounds which differ in their
properties from any of the non-nitrogenous
substances. Of such special properties the
most conspicuous is perhaps alkalinity. Like
ammonia, of which it is a derivative, the
amino group (— NH2), and various other
groups containing nitrogen possess this char-

CHEMISTRY 209

acteristic. Such compounds, accordingly,
supplement those which contain the acid
carboxyl group (- COOII) and make possible
the fundamental relations of acid, base, and
salt among organic compounds, corresponding
to those of inorganic chemistry.

There exist also many compounds of sul-
phur, of chlorine, bromine, and iodine, as
well as of various less common elements
among organic substances; but in all such
cases the complexity and variety of the
compounds depend primarily upon the ca-
pacity of carbon, hydrogen, and oxygen, or
carbon and hydrogen together, to form nu-
merous, varied, and complex compounds on
which, as it were, the further complexity is
superposed.

E

THE CHARACTERISTICS OF ORGANIC SUBSTANCES

Thus the great diversity of organic sub-
stances depends in the first instance upon the
quadrivalence of carbon, which makes of
the carbon atom in the organic molecule a
focus, from which chains of atoms may ex-
tend in four different directions; or, in the
case of double or treble ties, in three directions ;

1
or in but two: «-C->, ^C=>, «=C=»>,

210 THE FITNESS OF THE ENVIRONMENT

<-C=>. Next comes the fact that carbon
atoms, when otherwise exclusively in com-
bination with hydrogen, and under other
circumstances in lesser degree, possess an
almost unlimited capacity to join together
and form chains and rings in great variety.
The longest carbon chain yet synthesized oc-
curs in the compound hexakontane,1 C60H122,
a substance whose constitution is probably as
follows : —

CH3CH2CH2: CH2 -CHs-CHa.

(CH2)54

The stability of this substance justifies a
belief that even far longer chains of carbon
atoms can exist, and, in fact, there is no known
limit to the possibility of stringing carbon
atoms together.

No other element is believed to share both
of these characteristics, and there are various
reasons to suppose that the resulting pecul-
iarity of the system of organic compounds
is really unique. Turning to the periodic
classification of the elements, it will be seen
that carbon is a member of the first series.
Several of the elements of this series, unlike
all the other elements except hydrogen, pos-
sess very definite individual properties, which

1 " Hell und Hagele," Berichte, 22, 502 (1899).

CHEMISTRY 211

mark them off sharply from other substances.
Thus carbon bears relatively little resem-
blance to its neighbors silicon or titanium,
nitrogen to phosphorus or vanadium, oxy-
gen to sulphur or chromium; while hydro-
gen, of course, has a place quite apart in the
classification, and as an element appears to
be correspondingly unique.

It is, therefore, in the highest degree prob-
able that compounds made from elements of
such positive chemical characteristics and
very unusual properties will be unlike com-
pounds formed from other elementary sub-
stances. In this manner the periodic classi-
fication confirms our confidence in the results
of many decades of experience, which lead us
to believe that other elements are exceedingly
unlikely readily to form compounds com-
parable in number, variety, and complexity
with those of organic chemistry as we know it.

For more evidence we may turn to certain
further data of organic chemistry. I refer
principally to the character of the organic
radicals composed exclusively of carbon and
hydrogen. In making a rational classifica-
tion of the carbon compounds it has been
found convenient to commence with that
series of hydrocarbons, called paraffines, with
which the present discussion was begun.

212 THE FITNESS OF THE ENVIRNOMENT

From them other series may be derived by
making a substitution in the molecule. Thus
the substitution of a hydroxyl radical for a
single hydrogen atom leads from the paraf-
fine hydrocarbons, CnH2n+2, to the alcohols
CnII2ri+iOH; the substitution of a carboxyl
radical — COOH, for the methyl group — CIT3,
leads from the paraffine hydrocarbons
CnH2n+1CH3 to the acids CnH2n+1COOH.

Moreover, the classes of compounds thus
defined chemically fulfill the logical require-
ments of a class. They are collections of
well-characterized and very similar individual
things which differ greatly, and in well-marked
manner, from all other things. In other
words, growing complexity of the molecule,
when it consists only in increase in complexity
of the simple radical comprised of carbon
and hydrogen, of the formula CnH2n+u

CH3-, CH3CH2-, CH3CH2CH2-, CH3 CH2 CH2 CH2-

CH3x CH3.

>CH-, >CH-CH2-

ch/ ch/

CHs-CH.

>CH-
CH/

CH3v

CHr)C -
CH3/

has very little effect upon the properties of
the molecule. Thus the compound methane,

CHEMISTRY 213

CH4, very closely resembles normal butane,

CH3 * CH2 * CH2 ' CHa ; and again propionic
acid, CII3 • CII2 • COOII, and heptylic acid,
CH3CH2CII2- CH2- CIL- Clio- COOII, are

very much alike.

Quite different is the case when any other
radical accumulates in the molecule. For
instance, propyl alcohol, CII3*CII2*CII2()II,
which closely resembles ordinary alcohol,
CH3*CH2OH, is very different in its behavior
from glycerine, CH2OH CHOH CH2OII,
and similarly, acetic acid, CII3*COOH, differs
materially in properties from oxalic acid
COOH* COOII. Even more marked are the
differences when a radical accumulates upon
a single carbon atom. In successive stages
of oxidation ethane, CH3*CH3, yields alcohol,
CH3CH2OH, aldehyde, CH3CH(OH)2, which
by a secondary transformation goes over into
the more stable form CH3*CHO, and acetic
acid, CH3*C(OH)3, which similarly becomes
CH3*COOH. These changes correspond to
the conversion of ethane, that is monomethvl
methane, into dimethyl methane, trimethyl
and tetramethyl methane : —

CH3-CII3->CH3CH2CH3-+

CH,yH _ rw _> cn3\ r/CH3

ch3Ah "Ltl3 ch/l\chi.

214 THE FITNESS OF THE ENVIRONMENT

In the latter case the introduction of methyl
groups in place of hydrogen produces no appre-
ciable change in the general characteristics
of the substances ; in the former, the succes-
sive introduction of hydroxyl groups forms
substances belonging to three different classes
of compounds, — alcohols, aldehydes, and acids,
which have nothing in common. In short,
variation in the number and arrangement of
such groups as occur in the paraffine hydro-
carbon,

I I I

— C — CH3, — C — CH2— -C

I I I

C-,

is without manifest effect upon the more
important properties of the molecule, but
variation in the number and arrangement of
any other groups produces complete change
in its characteristic properties.

CHEMISTRY 215

It may perhaps he urged that this argu-
ment is fallacious, in that the increase of the
relative amount of hydroxy! in the above
cases is larger than the relative change in
radicals of the types — CH3, = CH2, =CH,
and == C. But, in the first place, it is evi-
dent that the latter four radicals are actually
different, and a priori there is no reason to
suppose that they should not greatly differ
in their effect upon the properties of a mole-
cule, for instance, to render dissimilar the
compounds normal pentane CH3CH2CH2*
CH2*CH3 and tetramethyl methane,

CH3\ /CH3
CH3/^\CH3,

which is not the case. In the second place,
the change from methane, CH4, to ethane,
CH3CH3, is a larger proportional change in
the molecule than the change from alcohol,
CH3CH2OH, to glycol, CH2OHCH2OH, or
aldehyde, CH3CHO, both of which produce
far greater changes in the properties.

In fact, the union of carbon with hydrogen
in organic compounds is a unique and peculiar
chemical relationship, upon which the proper-
ties of the carbon compounds, their number,
variety, and complexity largely depend. It
seems to make no important difference whether

216 THE FITNESS OF THE ENVIRONMENT

a carbon atom is attached to four hydrogen
atoms, or to one carbon and three hydrogens,
or to two carbons and two hydrogens, or to
three carbons and one hydrogen, or to four
carbon atoms ; in all such cases the effect
of the radical upon the general characteristics
of the molecule varies very little.

There are a great number of phenomena
which might be employed further to illustrate
the nature of the case, but two will suffice.
The acidity of acetic acid, CH3*COOH, is
only slightly and slowly changed by the
accumulation of hydrocarbon radicals ; thus
the compounds propionic acid, CH3*CH2'
COOH, and butyric acid, CHg-CHa'CHv
COOH, are only a little less acid than acetic
acid itself, because nearlv all the effect of
such larger radicals as they contain is already
exerted by the methyl group.

Ionization Constants of Acids

Acetic acid,

CH3 COOH

0.000018

Propionic acid,

CH3 • CH2 COOH

0.000014

Butyric acid,

CH3 CH2 CH> COOH

0.000016

Glycolic acid,

CH2OH COOH

0.00015

Chloracetic acid,

CH2C1 COOH

0.0015

Dickloracetic acid,

CHC12 COOH

0.05

Trichloracetic acid,

CC13 COOH

1.2

Glycocoll,

CH2NH2 COOH

0.00000000018

Oxalic acid,

COOH COOH

0.1

CHEMISTRY 217

But if a hydroxy! group be substituted, as in

glycolic acid, CH2OHCOOII, or a chlorine
atom, as in monochloracetic arid, CHaCl'
COOH, tlie acidity is greatly increased, while
the compound trichloracetic acid, CC13-
COOH, is a strong acid. On the other hand,
aminoacetic acid, CH2*NH2*COOH, is
scarcely acid at all.

The effect of introducing a carboxyl group
in place of a methyl group into any paraffine
hydrocarbon, regardless of its constitution,
e.g. CH3CH3->CH3COOH, is to diminish
the heat of combustion of the molecule almost
exactly 157 calories ; but the conversion of
acetic acid into oxalic acid, CH3*COOH->
COOH-COOH, structurally an identical
change, diminishes the molecular heat of
combustion only 147 calories.1 In both these
instances it is certain that the nature of the
influence of the radicals consisting of carbon
and hydrogen exclusively is nearly independ-
ent of their size and configuration. Any
other group, however, by its presence at once
modifies the nature of the case, though un-
concerned in the process or property. Since
it can be shown that such effects, like the
difference between monochloracetic acid and

1 Stohmann, Zeitschrift fur Physikalischc Chemic. II, 29,
1888.

218 THE FITNESS OF THE ENVIRONMENT

trichloracetic acid, depend upon the number
of such foreign groups and their arrangement,1
it is evident that the hydrocarbon radicals
have a constancy of influence upon the prop-
erties of the molecule which is not shared by
other radicals.

The indifference of effect of hydrogen and
carbon, when linked to carbon, upon the
properties of the molecule is undoubtedly a
principal cause of the stability of complex
organic substances. Through this peculiar-
ity of the two elements the integrity of the
valence energy of carbon is preserved, and the
long carbon chains are stable. Whenever
the molecule becomes overloaded with radi-
cals of other kinds the strength of the tie
between carbon atoms diminishes and the
compound becomes unstable. The proper-
ties of the carbohydrates, which will be later
discussed, admirably illustrate such instabil-
ity. In short, organic compounds are in some
respects properly to be regarded as compounds
of carbon and hydrogen jointly, for it is not
the properties of carbon alone, but those of
carbon and hydrogen together which chiefly
make them possible.

1 Henderson, Journal of Physical Chemistry, IX, 40, 1905 ;
Proceedings of the American Academy of Arts and Sciences,
XLII, 639, 1907; Zeitschrijt filr Physikalische Chemie, LX,
413, 1907.

CHEMISTRY 219

In the more complex substances, such as
the various ring systems of organic chemistry,
it is not possible to discuss such problems of
molecular mechanics. There too, however,
hydrogen predominates over all other elements
except carbon, and that may well be taken as
a sufficient indication of its continued im-
portance.

All of these considerations taken together
suffice, I believe, to prove, or at least to make
it exceedingly probable, that organic chemistry
is in truth a unique field, and that no other
elements can form compounds in such variety,
complexity, and number as carbon, hydrogen,
and oxygen. At any rate there can be no
possible doubt that the compounds of organic
chemistry are in these respects very remark-
able indeed, and that similar cases must be
extremely rare among all the possible systems
of compounds made up of all the known
elements.

It follows from the peculiarities just ex-
plained that the first great factor in the com-
plexity of living organisms as we know them,
the complexity and variety of their chemical
constituents, depends principally upon the
nature of the elements which compose such
substances, and is most probably a unique,
certainly a very rare characteristic of matter.

220 THE FITNESS OF THE ENVIRONMENT

That the very elements which make up water
and carbonic acid, and apparently they alone,
should possess this wonderful property is,
when taken together with the physical prop-
erties of water and carbonic acid and their
place in cosmic evolution as constituents of
the atmosphere, a fact which cannot lightly
be set aside.

Not less valuable for the organism than the
multiplicity of organic substances, and the
diversity of their properties, are the great
variety of chemical changes which they can
undergo, and that characteristic instability
which renders such great complexity of chem-
ical behavior easily attainable. In short,
organic substances are uniquely fitted not
only to provide complexity of structure to the
organism, but also, through their instability
and manifold transformations, to endow it
with diverse chemical activities, with com-
plexity of physiological function.

One factor in determining the complexity
of chemical changes which organic chemical
substances manifest is the enormous number
of simple structural relationships which every
substance bears to others. This may be
readily illustrated by the formulas of some of
the derivatives of propane which possess
biological importance : —

CHExMISTRY

221

CH,

CH3

CH3

i

CH3

i

CH2

CHo

CO

CO

CH2OH

COOH

CH3

CHO

Propyl alcohol,

Propionic acid,

Acetone,

Methyl glyoxal.

CH3

CHoOH

CHoOH

CHoOH

CHOH

CHOH

CHOH

CO

COOH

CH.OH

CHO

CHoOH

Lactic acid,

Glycerine

Glycerine
aldehyde,

Dioxvacetone

CH3

CHoOH

CHo SH

CH3

CH NH2

CH NH2

1

CH NHo

CH SH

COOH

COOH

COOH

COOH

Alanine,

Serine,

Cysteine,

a-Thiolactic
acid

Of the above substances, acetone, lactic acid,
glycerine, glycerine aldehyde, dioxyacetone,
alanine, serine, and cysteine are of the great-
est moment in physiological processes.

Such complexity of chemical relationships
results automatically, so to speak, in a variety
of chemical transformations. But the trans-
formations are greatly facilitated by thai
characteristic instability of organic substances,
which is perhaps the chief distinguishing fea-
ture of their behavior. For example, many
inorganic substances may be subjected to very

222 THE FITNESS OF THE ENVIRONMENT

high temperatures without undergoing chem-
ical change, but there are hardly any organic
substances which can survive such treatment.
Organic substances are also peculiarly liable
to modification from the action of light and
air. These are, however, but rough indica-
tions of instability, and a special case will help
more clearly to define the real characteristic.

THE SUGARS

In accordance with the researches of Emil
Fischer, the following constitution is ordina-
rily assigned to glucose.1

H

I

C = 0

I
H-C-O-H

I
H-O-C-H

I
H-C-O-H

I
H-C-O-H

CH2OH

1 A discussion of this formula may be found in any text-
book of organic chemistry.

CHEMISTRY 223

It must be noted that carbon atoms to
which four different groups are attached are
asymmetric, that is to say, they can exist in
two forms which resemble each other as the
right hand resembles the left (Pasteur, LeBel,
van't Hoff). This characteristic results in
further increase in the number and variety of
organic compounds. It is therefore neces-
sary, in writing the formula, to represent the
form of the molecule as it exists in space (in
three dimensions), and this is actually accom-
plished by imagining the three-dimensional
formula to be projected upon the paper so that
when the hydrogen atom is written to the right
of the carbon atom one asymmetric form of
the latter is designated, when the hydrogen
atom appears to the left, the other.

It has long been known that when glucose
is dissolved in water its optical activity, as
the power of a substance to rotate the plane
of polarization of light is loosely termed,
changes slowly for some time before reaching
a constant value. Recently it has been shown
that this phenomenon probably depends upon
the existence in solution of three different forms
of glucose, which pass freely into one another
and ultimately attain a state of equilibrium.1

1 This subject has been fully discussed by Hudson, Journal
of the American Chemical Society, XXXII, 889, 1910.

224 THE FITNESS OF THE ENVIRONMENT

OH

H-C—

I
H-C-OH

I
HO-C-H

I
H-C

O

H-C-OH

I
CH2OH

CHO
I
H-C-OH
I
HO-C-H
I
H-C-OH

I
H-C-OH
I
CH2OH

H

I
HO-C

H-C-OH

I
HO-C-H

H-C

O

H-C-OH
I
CHoOH

When to such a solution of glucose a small
quantity of alkali is added, certain remarkable
further changes occur, as was first demon-
strated by Lobry de Bruyn.1 These pro-
cesses result in the formation of mannose and
levulose, probably according to the accom-
panying diagram.

Moreover, like glucose, levulose and man-
nose both exist in solution in three different
forms, so that the resulting solution contains
at least ten chemical individuals. But it is
almost certain that other changes simultane-
ously occur and that the solution is actually
still more complex, even from the outset.

Upon a continued increase of alkalinity,
or even slowly under the original conditions,
a multitude of other changes set in. These

1 See the numerous papers by Lobry de Bruyn and Al-
berda van Eckenstein in Recueil des Travaux Chimiques
des Pays Bas, XIV-XIX.

CHEMISTRY

21

CHO

HCOH

HOCH

HCOH

1

HCOH

CH,OH

1

CH2OH

1

CHOH

II
C-OH

CHO

CO

HO-

-C-H

HO-C-H =^=

HO-C-H ^

HO-

-C-H

H-C-OH

H-C-OH

1

H-

-C-OH

1

H-C-OH

1

H-C-OH

H-

-C-OH

1

CH2OH

CH2OH

CH2OH

Levulose

Mannose

are known sometimes to lead to the formation
of lactic acid, CH3CHOHCOOH, methyl-
glyoxal, CH3*CO*CHO, and formaldehyde,
H-CHO. Further, as Neff has shown,1 many
other substances may also be formed. Such
bodies chiefly belong to the class of oxyacids.
It is also certain that a great variety of other
simple sugars resembling glucose, levulose,

iNeff, "Liebig's Annallen," 376, p. 1, 1910, and 357,
p. 294, 1907.

Q

226 THE FITNESS OF THE ENVIRONMENT

and mannose are produced, and, all told, the
constituents of such a solution probably
number at least two hundred, all produced
from glucose alone, under the influence of a
slight excess of hydroxyl ions. Among these
substances the greatest diversity of chemical
behavior is to be distinguished. Alcohol,
aldehvde and ketone, and acid radicals occur
in great profusion and variety of combinations ;
compounds possessing forked chains are pres-
ent ; and double bonds between carbon atoms
add to the complexity. Moreover, all these
substances themselves possess great chemical
activity.

A single case may perhaps illustrate this
point. It has been shown by Windaus and
Knoop l that in such solutions, in the presence
of ammonia, one molecule of methyl glyoxal,
one of formaldehyde, and two of ammonia
unite to form the cyclic compound, methyl
imidazol, a substance related to histidine,
the latter being an important constituent of
the protein molecule : —

CH3-C = 0 NH3 /H CH3-C-N/H

I C^O -> II ^>C-H

C=0 NH3 XH H— C-N^

H

1 Knoop and Windaus, Berichte, XXXVI, 1166, 1905.
Hofmeister's Beitrage, VI, 392, 1905.

CHEMISTRY 227

The instability of glucose and of all the
simple sugars is indeed exceptional in char-
acter, and the resulting processes arc perhaps
far more intricate and numerous than in any
other similar case. However, this very case
is of exceptional physiological importance, be-
cause carbohydrates are the direct result of
that synthetic action of chlorophyll,

6 C02 + 6 H20 - C6H1206 + 6 02,

which is the source of all organic substances
and of all the energy of the organic cycle in
plants and animals. Carbohydrates, more-
over, are the chief constituents of plants and
the chief food of animals.

Turning to this synthesis of carbohydrate
in the plant, we find much that is important
in the present study. The details of the
chemical transformation by which water and
carbonic acid and solar energy are changed
to sugars and oxygen still remain unknown,
in spite of many careful investigations. But,
at all events, it is possible to see that two
things must somehow be done in order to
accomplish the synthesis: —

(1) Carbonic acid and water must be re-
duced. That is to say, oxygen must be sepa-
rated from both of these compounds so that
free valences may exist to unite carbon and

228 THE FITNESS OF THE ENVIRONMENT

hydrogen in one molecule, and so that, further,
the relative proportions of the three elements
may become what they are in the simple
carbohydrates, C:H:0 = 1:2:1.

(2) Somehow individual carbon atoms must
be joined together until there are six in each
molecule, where formerly there was but one.

Theoretically, it might be possible by reduc-
tion to form from carbon dioxide and water
without union of carbon atoms the following
substances: carbon monoxide, CO; formic
acid, H-COOH; formaldehyde, HCHO;
methyl alcohol, CH3OH ; and methane, CH4.
Of such reductions the formation of formic acid,
formaldehyde, and carbon monoxide has been
directly realized by laboratory experiment.1

The most familiar theory of the formation
of carbohydrates in the leaf is that of von
Baeyer, which assumes a polymerization of
one of the above substances, formaldehyde,
leading directly to the formation of sugar,
according to the reaction

6HCHO=C6H1206.

This process also has been carried out ex-
perimentally. Indeed, as a result of the
investigations of Butlerow, O. Loew, and

^ee Meyer u. Jacobson's "Lehrbuch der Organischen
Chemie," Leipzig, 1907, p. 688, 693-696.

CHEMISTRY 229

E. Fischer, it is known that in distinctly alka-
line solutions formaldehyde spontaneously goes

over into a mixture of sugars which resemble
glucose. Moreover, such a solution is un-
questionably made up of much the same
variety of substances as a glucose solution
which has been subjected to the action of
alkali in the same concentration.

As stated above, it is evident that if any-
thing is to be done chemically with a mix-
ture of carbon dioxide and water, oxygen must
be split off from both carbon and hydrogen
so that they may enter into the same mole-
cule. If this chemical change, which, to be
sure, is no easy one in the laboratory, be ac-
complished, formaldehyde among other things
results ; and in alkaline solution formaldehvde
produces carbohydrates and leads to that
amazing tangle of substances and reactions,
whose nature has been briefly indicated above.
In short, the one chemical process ivhich is
open, if any transformations whatever are to be
accomplished with carbonic acid and water,
leads directly and to all appearances necessarily
to the greatest complexity that has been found in
any one chemical process; to a system made up
of possibly two hundred substances or more,
most of which possess very great chemical
activity.

230 THE FITNESS OF THE ENVIRONMENT

It must not be forgotten that the share of
the organism in such processes is also impor-
tant. If possible, the smoothness with which
chemical reactions are carried out in the leaf,
perhaps quite without any stop at the formal-
dehyde stage, and the certainty with which
definite substances in large amounts instead
of mixtures in very small amounts are pro-
duced, seem more remarkable than the under-
lying chemical facts. Needless to say, one
great factor in such processes is the action of
enzymes. Otherwise we are at a loss for a
description of the ways and means by which
the organism operates, though the brilliant
studies of chlorophyll which have recently
been carried out by Willstatter promise great
achievements in the future.1

The underlying chemical facts, however,
remain ; carbohydrates are among the natural
products of carbon dioxide and water; they
manifest in solution, especially in such con-
ditions as obtain in protoplasm or the ocean,2
unparalleled instability and variety of reac-
tions ; and they produce spontaneously an
enormous number of very active chemical
substances. It is easy to see that, given

1 See his many papers of recent years in "Liebig's Annal-
len."

2 Henderson, Journal of Biological Chemistry ', X, 3, 1911.

CHEMISTRY 231

an enzyme possessing the power to select and
catalyze any one of the reactions, the for-
mation of any special one of the many possible
products in comparative purity is an auto-
matic result.

Such processes are in nature carried out
with a perfection which to the chemist is
almost inconceivable, by means of organic
structures of the highest intricacy ; but in
the last analysis they rest upon the native
properties of the three elements.

The important consideration, I repeat, is
this : that reduction, the necessary first change
of carbonic acid and water, can lead directly
by a single continuous chemical transforma-
tion, of which the exact control is no whit
more remarkable than the accurate control
of the other processes of chemical physiology,1
to the full intricacy of organic chemistry ; to
the very most notable instance of number,
variety, and activity of substances, all formed
inevitably, in the nature of the case, which
has yet come to light. It is of no consequence
that most of the substances must be formed
in mere traces by the spontaneous synthesis,
for in highest degree the organism possesses
the power, by enzymatic catalysis, to select

1 Consult the work of Bayliss on Enzymes. London,
Longmans, Green & Company.

232 THE FITNESS OF THE ENVIRONMENT

any one of a group of simultaneous reactions
that may serve its needs, and make that one
predominant. In short, the fitness is recip-
rocal; the unique chemical adaptability of
the process and the unique chemical powers of
the living organism interlock.

Such, in brief, are the superlative advan-
tages which the properties of the compounds
of the three elements contribute to the organic
mechanism. They include number of sub-
stances, variety of substances, variety of
properties, variety of reactions, facility of
reactions (instability), and the remarkable
relationship between carbon dioxide and water
and the carbohydrates. And they insure
that extreme variety of chemical relationship
which especially fits organic substances, once
created, to be, throughout the various forms
of life, the source of still other bodies, and the
source of energy, by means of far-reaching
chemical changes rapidly accomplished.

G

HYDROLYSIS

In the course of digestion the principal
foodstuffs, carbohydrates, fats, and proteins,
undergo a series of changes which are substan-
tially the same for all. Such processes are
known as hydrolytic cleavage, or more loosely

CHEMISTRY 233

as hydrolysis. Essentially they amount to
successive splittings of the large molecules
of the native substances, each cleavage being
accompanied by the addition of a molecule
of water, until finally from starches and like
substances the simple sugars like glucose result;
from the fats, fatty acids and glycerine;
from the proteins, the so-called amino acids.
The cleavage of fats closely resembles the
hydrolysis of a simple ester; the cleavage
of proteins and carbohydrates a little more
remotely resembles the same process. Accord-
ingly, the hydrolysis of the simplest ester,
methyl formate, may serve as an illustration
of the nature of the reaction: —

H-C-O^CH3+HO lH = H-C-0-H+H-0-CH,

II : I II

o o

This process is nothing less than the typical
reaction between water and organic sub-
stances. Accordingly, it is not surprising that
such reactions are by no means confined to
the digestion of food. Once formed, the prod-
ucts of digestion are absorbed, the more
readily because of their simplicity, and, also
because of their simplicity, they carry into
the body no trace of the organism in which
they previously existed. But, if they are to

234 THE FITNESS OF THE ENVIRONMENT

be built up into the tissues of the animal,
they must now be turned back into such fats,
carbohydrates, and proteins as are character-
istic of his physical structure ; into glycogen,
haemoglobin, fibrinogen, etc. Accordingly,
they undergo a process which is the exact
reverse of the digestive change, in the simple
case: —

H-C-0-H + H-0-CH3 = H-C-0-CH3 + H-0-H

II II

o o

But this is by no means the end of the matter.
For example, glycogen thus formed in the
liver from the glucose of the portal blood is
soon torn down to glucose again. More-
over, there are a host of other special cases
of the same hydrolytic cleavage, or the re-
verse process, in mammalian physiology. For
instance, the formation of hippuric acid from
benzoic acid and glycocoll, and the formation
of urea itself from ammonium carbonate
belong to this same class. In fact, such
reactions make up a large part of all the
chemical changes which take place within
the organism.

It must not be imagined, however, that
hydrolytic cleavages are infrequent outside
the organism, or that the types of processes

CHEMISTRY 235

which occur within the organism are the only
ones of this class. There is no more common
and universally important reaction in organic
chemistry, and many compounds and classes
of compounds which have nothing to do with
the organism undergo hydrolysis. Moreover,
generally speaking, all reactions of this class
are very similar in their principal character-
istics, resembling one another both dvnami-
cally and statically. Spontaneously they oc-
cur not at all, or very slowly. Under the
influence of enzymes, of acids, and of alkalies
acting catalytically, that is to say, facilitating
the process without in the end taking part
in it, much as oil facilitates the action of a
machine, they progress rather slowly and
very smoothly. By-products are not formed ;
the reactions are simple, uncomplicated, and
reliable. Hence they enable the organism to
make all sorts of rearrangements and recon-
structions of chemical substances efficiently
and without loss of material.

The chief cause of such traits in hydrolysis
is the fact that the energy transformation
which accompanies the process is almosl
exactly nil. For it has been found in general
that chemical reactions which liberate much
energy are violent, hard to regulate, often
complicated by intricate side reactions, and

236 THE FITNESS OF THE ENVIRONMENT

complete. In contrast, those which are with-
out energy change generally proceed smoothly,
slowly, and without complication to a state of
equilibrium in which the reaction is very in-
complete.1 Under the latter circumstances
slight changes of conditions make possible
a reversal of the delicately balanced process ;
the reaction can be made to run in either
direction at will.

The absence of transformation of energy
accompanying hydrolysis may be illustrated
by a few typical cases chosen from the data
of simple substances.

Calories

Per Cent

+ 1.9
+4.3
-3.7
+2.0

0.2
0.3
0.3
0.3

Such measurements of heats of reaction fall
well within the limits of error of the method
of investigation, and there can be no doubt
that in all such cases the heat of reaction is
so small that it cannot be detected by the
ordinary methods of measurement.2

1 van't Hoff, "Acht Vortrage liber Physikalische Chemie."
Brunswick, 1902, Lecture 6.

2 Stohmann, Zeitschrift fur Physikalische Chemie, II, 29,
1888 (see also Ostwald's "Lehrbuch der Allgemeinen Che-

CHEMISTRY -237

Thus it is evident that the process possesses
another advantage. In the course of such
rearrangements no energy is lost. This con-
clusion is thoroughly confirmed by the studies
of the energy transformations of metabolism.
The body may carry on such processes as it
will, in the greatest variety and complexity,
rearranging and modifying its chemical struc-
tures to any extent, and there will never be
an appreciable wastage of precious material
or of equally precious energy in the process.

This process, as we have seen, is the char-
acteristic reaction between water and the
organic compounds. As such it is necessarily
one of our chief concerns ; its maximal fitness
as a means of regulation, and otherwise, there-
fore assumes real importance in the present
discussion.

n

INORGANIC CHEMISTRY

With the survey of organic chemistry we
have exhausted the compounds of carbon ;

mie"). These data are the most accurate now in existence
which permit an estimate of the heat of hydrolysis of non-
nitrogenous compounds. Numerous studies of protein deriv-
atives from Fischer's laboratory prove that the facts are
the same for these substances, and direct measurements
confirm the measurements of heats of combustion.

238 THE FITNESS OF THE ENVIRONMENT

not so those of hydrogen and oxygen. In
almost equal frequency the latter elements
take part in the reactions of inorganic chem-
istry, and help to form its molecular struc-
tures. As an illustration of their importance
in this department of the science I have
counted the compounds and the classes of
compounds mentioned in the table of con-
tents of the second edition of Erdmann's
* * Lehrbuch der Anorganischen Chemie. ' : In all
435 substances are referred to ; of these 259,
approximately 60 per cent, contain oxygen ;
130, or 30 per cent, contain hydrogen. There
seems to be little doubt that this is a fair
test, for the work is compendious, and all im-
portant substances and classes of substances
are mentioned. Even if the acids, and the
small number of bodies which are referred to
in connection with their water of crystalli-
zation, be eliminated from the above count
the great importance of the two elements
remains clearly evident.

Only about one fourth of all the compounds
mentioned contain neither hydrogen nor oxy-
gen. A very large proportion of these con-
sist of the chlorides, bromides, iodides, sul-
phides, fluorides, and other similar binary
compounds, whose importance certainly does
not depend upon the variety of chemical

CHEMISTRY 039

reactions into which they may enter, while
their formation unquestionably docs depend
upon the intervention of both hydrogen and
oxygen. All told, the chemical substances
which contain neither carbon, nor hydrogen,
nor oxygen make up only a few per cent of
known bodies.

It is also clear that an especially large pro-
portion of the most active inorganic com-
pounds contain either hydrogen or oxygen.
All acids contain hydrogen; most of them
oxygen as well. All bases contain oxygen.
Moreover, the most important classes of re-
actions of inorganic chemistry are probably
oxidations and reductions, and the formation
of salts from acids and bases. In such pro-
cesses both oxygen and hydrogen are con-
cerned.

In addition to the oxides and resulting
bases and acids, a few other important sub-
stances wThich contain hydrogen or oxygen
may be cited : ozone 03, hydrogen peroxide
H202, ammonia NH3, hydrazine N2H4, hydrox-
ylamine NH2OH, sulphuretted hydrogen H2S,
hydrochloric acid HC1, nitrosyl chloride NOC1,
thionyl chloride SOCl2, phosgene COCl2, phos-
phine PH3, phosphorus oxychloride POCl3,
arsine AsH3. Such compounds, and many
other similar ones, are of great importance on

240 THE FITNESS OF THE ENVIRONMENT

account of the variety of chemical processes
into which they can enter. They make up
the active agents of inorganic chemistry, and
it is safe to assume that their activity depends
in great part upon the properties of oxygen
and hydrogen.

The importance of oxygen and hydrogen
in inorganic chemistry possesses a double
significance in the present inquiry. In the
first place it provides further confirmation
of the view that the elements which make
up water and carbon dioxide are unique. For
the data of inorganic chemistry prove that
hydrogen and oxygen are likely to confer
great chemical activity wherever they are,
and that they are quite unrivaled in this
respect. Secondly, the occurrence of hydrogen
and oxygen as primary factors of the metabolic
process and as the chief constituents of the
environment and of the living organism enables
the latter to make use of other elements at
need. Without hydrogen and oxygen, op-
portunities for the introduction of such other
elements into the physiological processes would
be necessarily much restricted, and in many
cases the physiological utility of compounds
containing the elements of inorganic chemistry
is very great.

Chlorophyll, for example, contains mag-

CHEMISTRY 241

nesium, and it is thought that the process of
reduction in the leaf may depend upon the
characteristic properties of this element ; at
all events, in organic chemistry, magnesium,
when employed in Grignard's reaction, is one
of the most effective agents to accomplish
reductions.

In like manner, haemoglobin contains iron,
and the capacity of haemoglobin to unite
with oxygen, and as oxy haemoglobin to carry
it from the lungs to the tissues is unquestion-
ably due to the chemical behavior of that
metal. Other similar metallic elements, no-
tably copper in the class of compounds known
as haemocyanines, fulfill a similar function in
lower animals.

Phosphorus in organic union is an essential
constituent of a great variety of the chemical
structures of living organisms, — the nucleic
acids, which appear to be not less important
than fats, carbohydrates, and proteids them-
selves in both animal and plant cells, contain
phosphorus as an essential constituent. Thus
phosphorus follows close upon nitrogen, after
carbon, oxygen, and hydrogen, as structural
material in biological chemistry. This same
element also occurs in many other compounds,
the simplest derivative of such bodies being
glycerophosphoric acid,

242 THE FITNESS OF THE ENVIRONMENT

CH2OH
I
CHOH

\ />-H

0-PM3

X0-H,

a compound of phosphorus, hydrogen, and
oxygen with glycerine.

Sulphur is a constituent of the proteins,
and occurs in many other important com-
pounds. In the metabolic process of the
animal sulphur is converted from a derivative
of hydrogen sulphide, H2S, by oxidation, into
sulphuric acid, H2S04, and in the plant the
process is reversed.

Iodine occurs in the thyroid and in many
marine organisms. The availability of this
element depends upon its existence in nature
as iodides, that is to say, upon its capacity
to unite with hydrogen to form hydriodic
acid, HI. Finally, it is the analogous com-
pound of chlorine with hydrogen, hydro-
chloric acid, which contributes acidity to the
gastric juice.

This list might be much further extended,
but I think that the nature of the case is now
established. The conclusion seems inevitable

CHEMISTRY £43

that active, diverse, and important inorganic
substances usually contain oxygen or hydro-
gen, and that it is the union of other elements
with these two which renders them available
and useful to the organism.

Ill

THERMOCHEMISTRY

Every chemical change consists in simul-
taneous rearrangements of matter and energy.
The true nature of the chemical process is to
be sought neither in the one nor in the other
of these two phenomena, but in both together ;
and properly energy is as much the chemist's
concern as matter itself.

Thus far in the present investigation, con-
siderations regarding energy have been avoided
except in the case of hydrolytic cleavages, and
these constitute a unique class of reactions*
No other large and important class is char-
acterized by inappreciable heat of reaction,
for it is as heat that chemical energy commonly
manifests itself when liberated. It is evident,
however, in accordance with the fundamental
postulates, that the organism must have
energy to actuate as well as matter to form
its mechanism. Therefore the nature of the
energy transformations, which make up one

244 THE FITNESS OF THE ENVIRONMENT

aspect of the chemical reactions into which
carbon, hydrogen, and oxygen enter, must be
now noticed.

It has been shown above that the one pos-
sible chemical process by means of which any-
thing can be made out of the primary con-
stituents of the environment is reduction, —
the more or less complete tearing off of oxygen
from carbon and hydrogen atoms in the mole-
cules of carbon dioxide and water. As a
function of the extent of the reduction the
energy change involved in the process will
vary. In all cases, however, the process is
accompanied by large absorption of heat, as
the following table of the energy absorbed
per gram of the resulting substance, when
reduction begins with water and carbonic
acid, may indicate: —

H2 34.5 Cal.
C 8.1

CH4 13.3
CH3OH 5.3

HCHO 4.2

C6H1206 3.74

CO 2.4

HCOOH 1.4

Such new compounds hold their energy
only so long as they persist unchanged, and

CHEMISTRY 245

upon oxidation they yield it all back again,
just as water vapor on condensing yields
back the latent heat which it has taken up
during evaporation. In this manner, every
gram of glucose or other monosaccharide is
necessarily a temporary depository of solar
energy amounting to about 3.74 calories,
taking up just that amount of energy when
synthesized by chlorophyll, yielding it back
when burned in the muscle.

Compounds of carbon and hydrogen are
especially well qualified to be reservoirs of
energy which may be liberated by oxidation,
as the following table shows: —

HEATS OF COMBUSTION OF ELEMENTS PER GRAM

Hydrogen

34.5 Cal.

Carbon

8.1

Sulphur (to S02)

2.3

Sulphur (to

S03)

3.2

Nitrogen (to N02)

0.2

Phosphorus

5.9

Boron

12.3

Silicon

3.3

Potassium

1.3

Calcium

3.3

Aluminium

7.0

Hydrogen, it will be seen, far exceeds any
other element in the amount of heat that it

246 THE FITNESS OF THE ENVIRONMENT

yields upon oxidation; carbon is surpassed
by but one other element, boron. Although
necessarily a good deal of this heat cannot be
stored in the compounds of the two elements
which still contain some oxygen, yet enough
remains to make the common constituents
of the organism greater reservoirs of energy
than most of the other elements themselves,
far greater than compounds of any other
elements. Thus the heat of combustion of
carbohydrates ranges from about 3.7 calories
to about 4.2 calories per gram, that of the
proteins from about 5 calories to about 6
calories, that of the fats from about 9.2 calo-
ries to about 9.5 calories. On account of the
small quantity of oxygen and the large quan-
tity of hydrogen which they contain, the fats
are a richer source of energy than carbon
itself, or than any other element except hydro-
gen and boron.

There remains one other equally important
consideration to be dealt with: the very great
energy change which is involved in processes
of oxidation and reduction compared with
other chemical processes. The following
table, showing the amount of heat liberated
in the process of formation of certain binary
compounds from their several elements, illus-
trates the case: —

CHEMISTRY

1A

HEATS OF

FORMATION

H20

3.83 Cal.

CSa

-0.25 Cal

C02

2.22

Nad

1.67

HC1

0.60

LiCl

2.20

HF

1.97

NaBr

0.87

NPI3

1.23

NaF

2.64

02V>12

0.08

1

Na2S

1.14

ecu

0.49

SiH4

-0.21

PI3

0.26

SiF4

2.31

BC13

0.79

NS

-0.69

Oxygen, as will be seen, far surpasses the
other chemical elements (except fluorine) in
the amount of energy liberated in the process
of its chemical union with other substances.

Accordingly, it may be concluded that, on
the whole, oxidations are the best chemical
source of energy ; reductions the best means
of storing energy by chemical processes;
and that among oxidations and reductions
those of hydrogen especially, and then those
of carbon, are associated with the largest
energy transformations.

This is the last argument which I have to
present, but it is one of the most potent. The
very chemical changes, which for so many
other reasons seem to be best fitted to be-
come the processes of physiology, turn out to
be the very ones which can divert the greatest

248 THE FITNESS OF THE ENVIRONMENT

flood of energy into the stream of life; and
these are the reactions automatically provided
for by the cosmic process.

From the materialistic and the energetic
standpoint alike, carbon, hydrogen, and oxy-
gen, each by itself, and all taken together,
possess unique and preeminent chemical fit-
ness for the organic mechanism. They alone
are best fitted to form it and to set it in motion ;
and their stable compounds, water and car-
bonic acid, which make up the changeless
environment, protect and renew it, forever
drawing fresh energy from the sunshine.

CHAPTER VII
THE ARGUMENT

THE statement of evidence for the bio-
logical fitness of the environment is at
length completed. Whatever favorable prop-
erties of water, carbonic acid, and the com-
pounds of the three elements, whatever results
favorable to life, I have succeeded in finding,
have been set forth.

Now, therefore, we may return to the exam-
ination of this evidence in the manner sug-
gested in Chapter II. We may inquire into
the exhaustiveness of the preceding treatment
of important physical properties, seeking to
discover what things have been overlooked.
Thus it may be possible to decide the weighty
question whether another group of elements
can possess another group of equally impor-
tant properties. Next, we may consider if
there be other elements or compounds which
rival carbon, hydrogen and oxygen, water and
carbonic acid, in the qualities which make
these fit for the organic mechanism, taking
such properties as a whole. Unfortunately,

249

250 THE FITNESS OF THE ENVIRONMENT

in adopting this somewhat rigid logical
method, tedious and perhaps unnecessary
repetition is involved, but the advantages of
care at this stage of the inquiry seem to be
very great, for it is not easy to survey so
large a field, and at best certainty that impor-
tant oversights have been avoided is obviously
impossible. For example, peculiarities like the
anomalous expansion of water, or the relation
of carbonic acid and water to the carbohy-
drates are not to be foreseen. On the other
hand, the more general characteristics of
matter are well known and, for the most part,
must reveal themselves to diligent search.

ANALYSIS OF THE EVIDENCE

First the natural phenomena which seem to
be concerned in fitness may be brought to-
gether analytically, and their effect briefly
summarized.

NATURAL PHENOMENA WHICH PROMOTE FITNESS
IN THE ENVIRONMENT

I. The occurrence of great quantities of
water and carbon dioxide outside
the solid crust of an astronomical
body.

THE ARGUMENT J51

II. Properties of Water.

a. Specific Heat.

b. Freezing Point.

c. Latent Heat of Fusion.

d. Latent Heat of Vaporization.

e. Vapor Tension.

/. (Thermal Conductivity.)

g. Expansion before Freezing.

h. (Expansion in Freezing.)

i. Solvent Power.

j. Dielectric Constant.

k. Ionizing Power.

/. Surface Tension.

III. Properties of Carbon Dioxide.

a. Solubility in Water.

b. Ionization Constant.

IV. Properties of the Ocean.

a. Number and Variety of Constituents.

b. Quantity of Dissolved Material.

c. Mobility.

d. Constancy of Temperature.

e. Constancy of Osmotic Pressure.
/. Constancy of Alkalinity.

g. Constancy of Composition.
V. Chemical Properties of Carbon, Hydro-
gen, and Oxygen.

a. Number of Compounds.

b. Variety of Compounds.

c. Complexity of Compounds.

252 THE FITNESS OF THE ENVIRONMENT

d. Number of Reactions.

e. Variety of Reactions.

/. Complexity of Reactions.

g. The Evenness and Lack of Energy
Change of the Process of Hydro-
lytic Cleavage.

h. The Chemical Relationship of Car-
bonic Acid and Water to the Sugars.

i. Instability of the Sugars.

j. Variety and Reactions of the Sugars.

k. Heats of Reaction in Organic Chemis-
try.

L The Number and Variety of Com-
pounds and Reactions of Oxygen
with Other Elements.

m. The Number and Variety of Com-
pounds and Reactions of Hydro-
gen with Other Elements.

All the properties or other phenomena
noted in the above table (except II /, and II h)
are in character or in magnitude either unique
or nearly so, and are in their effect favorable
to the organism as defined in the fundamental
postulates. Indeed, they constitute or bring
about an extraordinary set of conditions
favorable to life, — ubiquity, abundance, va-
riety, stability, mobility, constancy of composi-
tion, and in variance of physico-chemical con-

THE ARGUMENT ££9

ditions in the environment; number, variety,
complexity, adaptability, availability, activity,
and richness in energy of the substances which
take part in the metabolic processes and in
the chemical and physical format ion of the
organism ; constancy of physico-chemical con-
ditions, such as temperature, alkalinity, col-
loidal disperseness, etc., within the organism;
the efficiency of many physiological processes ;
the availabilitv of electrical forces, etc.

In short, by many independent and united
actions the above catalogued natural char-
acteristics of the environment promote and
favor complexity, regulation, and metabo-
lism, the three fundamental characteristics
of life upon which all our discussion has
been based.

II

THE EXHAUSTIVENESS OF THE TREATMENT

One manner of judging the completeness
with which different types of phenomena and
properties, different elements and compounds,
have been considered in the descriptive chap-
ters preceding is to glance at the several
departments of physical science, chemistry,
mechanics, heat, sound, light, magnetism, elec-
tricity, and physical chemistry.

254 THE FITNESS OF THE ENVIRONMENT

In setting out to consider physical and
chemical properties we may perhaps begin
with chemical phenomena in the narrowest
sense. Such phenomena depend, according
to the atomic theory, upon rearrangements
of atoms within molecules. They result in
the conversion of individual substances into
one another, and they are accompanied by
rearrangements of energy.

In the first place, it is to be noted that
enormous quantities of carbon, hydrogen,
and oxygen, as water and carbonic acid, are,
during a very long period of time, apparently
inevitable constituents of the atmosphere of
an astronomical body of sufficient size, after
cooling has led to the formation of a crust.
Further, it has been shown that in number,
variety, complexity of forms and changes, and
in the magnitude of the accompanying trans-
formations of energy the known substances
made up of carbon and hydrogen, and those
made up of carbon, hydrogen, and oxygen far
surpass the compounds of any other elements.
Likewise the known compounds of oxygen and
hydrogen with other elements are the most
numerous and important among inorganic
substances. Two peculiarities of the carbon
compounds, the formation and properties of
the carbohydrates, and the nature of the pro-

THE ARGUMENT 155

cess known as hydrolytic cleavage, add to this
list of chemical characteristics which make
for fitness.

These facts appear to indicate that in gen-
eral chemical behavior, in certain special
characteristics as well, and in the magnitude
of the quantity of energy rendered available
by their chemical changes, the elements car-
bon, hydrogen, and oxygen are uniquely and
most highly fitted to be the stuff of which life
is formed and of the environment in which it
exists.

Mechanics has taken a place subordinate
to chemistry in the present work. Neverthe-
less, it has been noted that the unique proper-
ties of water are the cause of the admirable
mobility of that substance and of the whole
environment, and therefore of the dynamical
processes of geology, meteorology, etc., in-
cluding soil formation ; that it is surface ten-
sion which holds water in the soil ; that the
efficacv of water as a means of dissolving the
greatest variety of substances in the greatest
amounts, makes possible high osmotic pres-
sures, as wTell as mobility of all the elements;
and there are a host of other considerations
which have been discussed above. In all
such cases the properties of water have been
found to be favorable influences for the wel-

256 THE FITNESS OF THE ENVIRONMENT

fare of the organism. Considering the com-
parative unimportance of mechanics in rela-
tion to the fundamental postulates, it seems
clear that this department has not been over-
looked.

Thermal processes and thermal effects are
perhaps more conspicuous in the table. The
thermochemical characteristics of organic com-
pounds and the thermal properties of water
are all very favorable to life. Stores of heat
for the organism, constancy of temperature
of both organism and environment, the per-
manence of bodies of water, and a multitude
of other most important results flow from these
properties and bear witness to their unique
fitness.

Sound, light, and magnetism have not been
considered, for they appear to bear only a
secondary relation to the fundamental postu-
lates.

In electricity no phenomena are more im-
portant than those of ionization in solution.
To bring about ionization and thus make
possible electrochemical processes, water is
the very best medium, and the possibility of
such processes is probably necessary to the
organic mechanism.

In addition to the topics of physical chem-
istry already referred to under chemistry

THE ARGUMENT 257

and the several departments of physics, the
colloids and the ions of hydrogen and hydroxy]
remain to be mentioned. It has been shown

that the properties of water arc exceptionally
favorable to the existence and stability of
colloidal systems; also that the properties of
carbonic acid result in automatic regulation
of the concentration of hydrogen and hydroxy]
ions in the ocean and in the organism.

So far, then, as it is possible to judge by
telling over the departments of physical
science, our examination of physical and chem-
ical properties has not been incomplete.

This conclusion may be further tested with
the help of the ideas which underlie YVillard
Gibbs's " Phase Rule." l According to this rule,
the condition of equilibrium in any material
system depends upon the number of its com-
ponents, the number of its phases, temperature,
pressure, and, in general, the concentrations
of all the components. Without entering
upon an explanation of the exact mathemat-
ical notions which determine the meaning
of the terms "component' and "phase' it
will here suffice to say that in general the
number of components increases as the num-
ber of separate chemical individuals increases,

1 See, for instance, Findlay, "The Phase Rule and its
Applications." London, 1911, 3d ed.

8

258 THE FITNESS OF THE ENVIRONMENT

and that a phase is any solid, liquid, or gas-
eous part of the whole system which possesses
homogeneity of composition. For instance,
if a system is made up of sand, salt solution,
ice, and aqueous vapor, each of these separate
parts, in that it is homogeneous, is a phase.

Now the properties of water have the result
that more readily than other substances it
exists simultaneously and in large quanti-
ties in the three phases of solid, liquid, and
gas as ice, water, and aqueous vapor. This
depends upon the high latent heats of fusion
and vaporization, the high freezing point of
water, and its vapor tension. Water en-
hances the complexity of the environment,
and is one principal factor in the mobility of
the environment as a whole. Further, it
makes for stability ; other things being equal,
the greater the number of phases, the less the
tendency to change. Among phases the dis-
perse colloidal type is unique and of very
great importance — almost the sole basis,
indeed, of great physical complexity — and,
as above shown, the peculiar properties of
water highly favor the colloidal condition.

The solvent power of water much increases
the number of components which may enter
into a system of which it is a part ; hence the
large number of components of sea water,

THE ARGUMENT 250

blood plasma, etc. The variety of compounds,
both organic and inorganic, which contain
carbon, hydrogen, or oxygen also causes enor-
mous increase in the number of components
of biological systems like protoplasm.

The effects of the properties of water above
enumerated to regulate temperature are almost
too numerous to mention. The specific heat
of water, its latent heats of fusion and vapori-
zation, and the high freezing point all con-
tribute to the restriction of temperature range
within the organism, in the waters, and over
the whole surface of the earth. The vapor
pressure of water has been shown to possess
great and exceptional variability wTith change
of temperature. This is the most impor-
tant property of water meteorologically, and
is the necessary condition for its ample cir-
culation. The ratio between the gas pressure
of carbonic acid and its concentration in
water (absorption coefficient) has been shown
to be the great factor in establishing the mo-
bility of that substance. The total atmos-
pheric pressure has not entered into our dis-
cussion, for it seems to have no important
special relation to the properties of the three
elements.

In short, the properties of water and of the
carbon compounds provide for number, va-

260 THE FITNESS OF THE ENVIRONMENT

riety, and complexity of phases and compo-
nents, and for constancy of temperature, while
equally important and unique relationships
between the properties of water and carbonic
acid and their vapor or gas pressures exist,
and exert much influence upon the meteoro-
logical cycle.

Thus, judged by the phase rule, the actual
characteristics of the environment may be
shown to contribute the factors which make for
complexity and regulation of material sys-
tems. Now there can be no doubt that, when
feasible, the ideal method — from the physico-
chemical point of view — to describe a ma-
terial system is in the terms of the phase
rule.1 Hence the characteristics which that

1 "Ten years after the law of mass action was propounded
by Guldberg and Waage, Willard Gibbs, Professor of Physics
in Yale University, showed how, in a perfectly general manner,
free from all hypothetical assumptions as to the molecular
condition of the participating substances, all cases of equi-
librium could be surveyed and grouped into classes, and how
similarities in the behavior of apparently different kinds of
systems, and differences in apparently similar systems, could
be explained.

" As the basis of his theory of equilibria, Gibbs adopted the
laws of thermodynamics, a method of treatment which had
first been employed by Horstmann. In deducing the law of
equilibrium, Gibbs regarded a system as possessing only three
independently variable factors — temperature, pressure, and
the concentration of the components of the system — and he
enunciated the general theorem now usually known as the

THE ARGUMENT 261

rule contemplates are in certain respects the
most important of characteristics. Accord-
ingly the above test is a valuable indication
of the adequacy of the preceding analysis of

physical and chemical properties.

In order if possible to discover the nature
of such properties of matter as may have been

omitted in our study of fitness, I have ex-
amined the index of Landolt and Bdrnstein's
"Physikalisch-chemischen Tabellen," a very
extensive and comprehensive work. In addi-
tion to information regarding the arbitrary
units of physical science, I find mention of the
following properties which have not been
considered in the present discussion: —

The Mechanical Equivalent of Heat.

The Dimensions of the Angles of Crystals.

The Refraction of Light.

Compressibility.

The Dimensions of the Molecules of Gases.

Elasticity.

The Electromagnetic Rotation of the Plane

of Polarization of Light.
Color.

Phase Rule, by which he defined the conditions of equilibrium
as a relationship between the number of what arc called the
phases and the components of the system." — Findlay,
"The Phase Rule and its Applications." London, 1911, 3d
ed., p. 8.

262 THE FITNESS OF THE ENVIRONMENT

Viscosity.

Torsion.

The Velocity of the Molecules of Gases.

Hardness.

Magnetism.

The Velocity of Light.

Optical Activity.

Friction.

The Velocity of Sound.

The Wave Length of Light.

The Length of the Path of a Gaseous Particle.

To these may be added the phenomena of
radioactivity, etc.

It is clear that in the present state of
knowledge the consideration of most of these
properties is uncalled for. However, it may
perhaps be noted in passing that the com-
pressibility of water is remarkably small, that
of protoplasm even less.1 Hence even great
changes in pressure do not readily damage the
organism, and, indeed, a frog's muscle appears
to function normally after undergoing a
pressure of 500 atmospheres.2 Further, it is
of decided consequence for many reasons
that the optical properties of water are such

1 Henderson and Brink, American Journal of Physiology,
XXI, 248, 1908.

2 Henderson, Leland, and Means, American Journal of
Physiology, XXII, 48, 1908.

THE ARGUMENT 268

that light readily penetrates it to considerable
depths. As for color, landscape and modern

chemical industry alike testify to the availa-
bility of carbon compounds as its source.

A final test of thoroughness may be based
upon a consideration of other compounds

and elements. Accepting the decision thai
no other properties can be so important to
an active, complex, and regulated mechan-
ism as those possessed nearly or quite as
maxima by water, carbonic acid, and the
compounds of the three elements, what are
the possibilities of obtaining the same char-
acteristics from other substances ?

So far as chemical substances are now
known, the only compound which can be even
considered on this score as a substitute for
water in the environment is ammonia, and
in many respects, no doubt, ammonia might
serve as well.1 However, chemical proces- s

1 A full discussion of the properties of ammonia which qual-
ify it as a substitute for water in the role of solvent and other-
wise will be found in the article by E. C. Franklin, 'The
Ammonia System of Acids, Bases, and Salts," American Chem-
ical Journal, Vol. 47, p. 28.5, 191-2. In this paper the re-
sults of a long series of investigations an- brought together.
Especially important for the present purpose are the intro-
ductory remarks. "The many striking analogies between
liquid ammonia and water as electrolytic solvents have been
emphasized by the writer and Ins co-workers in papers which
have appeared from time to time during the past decade. In

264 THE FITNESS OF THE ENVIRONMENT

being what they are, it is impossible to im-
agine the presence of vast amounts of am-
monia in an atmosphere, while the loss of
the greater part of the energy which can be
stored by tearing apart hydrogen and oxygen
would be a very serious difficulty ; but the
loss of substantially all the incomparable
chemical activity of oxygen is to all appear-
ances an insurmountable obstacle to the sub-
stitution of ammonia for water in biological
processes.

From time to time, loose discussion has
arisen among chemists as to the possibility
of substituting another element for carbon in
the organic cycle. Such speculations have
never been serious, but they have at least

all those properties which give to water its unique position
among solvents, such as its abnormally high boiling point,
its high specific heat, its high heat of volatilization, its high
critical temperature and pressure, its high association con-
stant,-its high dielectric constant, and its low boiling-point
elevation constant, its power as an electrolytic solvent, and
the facility with which it forms compounds with salts, liquid
ammonia shows a remarkable similarity to water."

" While the boiling point of liquid ammonia is 33.46° below
zero, it still appears abnormally high when compared with
the boiling temperatures of phosphine, arsine, stibine, me-
thane, ethylene, hydrogen sulphide, hydrochloric acid, etc.
The specific heat of liquid ammonia and the heat of fusion
of the solid are greater than the corresponding constants
for water or any other known substance, while its heat of
volatilization, with the one exception of water, is the highest

THE ARGUMENT 265

demonstrated that very few elements, prob-
ably only silicon, and perhaps boron, can
even be imagined in such a role. It h;i>.
moreover, just been shown that there are
many facts leading to the conclusion that
only carbon among elements, and carbon itself
only in conjunction with hydrogen, has the
power to form the skeletons of compounds
numerous, complex, and varied like those of
organic chemistry. But, apart from this
conclusion, it is certain that silicon and boron
could not be mobilized like carbon. Quartz,

of any known liquid. The critical temperature of ammonia
is abnormally high, and its critical pressure — the more char-
acteristic constant — is higher than that of any other liquid
excepting water. Ammonia is an associated liquid, and its
dielectric constant, though much below that of water, is still
high when compared with that of non-electrolytic solvents.
Its boiling-point elevation constant is the lowest of any
known liquid, namely 3.4, as compared with .V2 for water.
In its tendency to unite with salts and other compounds, it
probably exceeds water, since salts with ammonia of crystal-
lization are perhaps even more numerously recorded in the
literature than are salts with water of crystallization. As a
solvent for salts it is generally much inferior to water, though
some salts, for example the iodides and bromides of mercury,
lead, and silver, dissolve very much more abundantly in
ammonia than they do in water, and it far surpasses the latter
solvent in its ability to dissolve the compounds of carbon.
Finally it exhibits conspicuous power as an ionizing solvent,
the more dilute ammonia solutions at .'>:>. 5° being very much
better conductors of electricity than aqueous solutions of the
same concentration at 18°."

£66 THE FITNESS OF THE ENVIRONMENT

the oxide of silicon, is the most inert and
immobile of rocks : the oxide of boron is only
less available s a movable constituent of the
environment : and there is no other stable
compound of either element which can be
compared with carbonic acid for its mobility.
It must be remembered that this property
is the result of two independent characteris-
tics of the latter substance, its gaseous na-
ture, and the precise degree of its solubility
in water. Finallv. the regulation of the
reaction of aqueous solutions by means of
carbonic acid has to be taken into account.

Hence it mav be concluded that hvdrosen,
oxvsen. and carbon, water and carbonic
acid, are not to be rivaled in their own qual-
ities, even as these cannot be balanced bv
others which they do not posse —

On the whole, then, we mav believe that the

m

physico-chemical characteristics of material
systems and material processes have been com-
prehensively examined in the course of the
present study. Accordingly, we may finally
conclude that the fitness of water, carbonic
acid, and the three elements make up a unique
ensemble of fitness for the organic mechanism.
The search, however incomplete, has certainly
not overlooked properties so important and
jmerous. or compounds and elements so

TEZ ;i

arises,
of water, carbonic acid,

m

F : t 11 r : r 15 11:

ri: -__.;_ lii rrl It 1

11 f . . -

1111 r

H. Iifr a iMcfcww Inm

point of vie-a- of p

A - 1_r

268 THE FITNESS OF THE ENVIRONMENT

a. Complex (physically, chemically,

physiologically) .

b. Durable, hence well regulated

physico-chemically. This con-
clusion applies to —

1. The Organism.

2. The Environment.

c. Endowed with a metabolism.

Hence there must be ex-
change with the environment
of —

1. Matter.

2. Energy.

III. The primary constituents of the natural

environment are —

a. Water.

b. Carbonic acid.

IV. In places where life is possible the

primary constituents of the
environment are necessarily
and automatically formed in
vast amounts by the cosmic
process.
V. Water, carbonic acid, and their con-
stituent elements manifest
great fitness for their biologi-
cal role.
a. Water possesses a great number of
unique or very unusual prop-

THE AR(,!Mi;\T ?f>{)

erties, e.g. thermal proper-
ties, solvent power, dielectric
constant, surface tension,
which together result in max-
imal fitness in certain respects,
e.g. mobility, ubiquity, con-
stancy of temperature and
richness of the environment,
richness of the organism in
chemical constituents, variety
of chemical processes, electri-
cal phenomena, colloidal phe-
nomena.

b. Carbon dioxide possesses very un-

usual properties, e.g. mag-
nitude of absorption coeffi-
cient, strength as acid, which
together result in maximal fit-
ness in certain respects, e.g.
mobility, ubiquity, richness of
the environment and organ-
ism in other elements and
compounds, constancy of re-
action, etc.

c. Chemical compounds containing

carbon, hydrogen, and oxygen
possess unique properties, e.g.
number, variety, complexity,
activity, variety of chemical

270 THE FITNESS OF THE ENVIRONMENT

relations and reactions, heats
of reaction, instability, etc.,
which together result in maxi-
mal fitness in certain respects,
e.g. as sources of matter and
energy for the processes of
metabolism, as sources of com-
plex structures, as the means
of establishing complex func-
tions, etc.
VI. Oceans are formed automatically in

the cosmic process.
VII. The ocean possesses unique properties,

e.g. mobility, richness in dis-
solved substances, durability,
and stability of physico-chem-
ical conditions, depending
chiefly upon the properties of
water and carbonic acid, which
together result in maximal fit-
ness in certain respects, e.g.
as milieu, and as source of
matter for the processes of
metabolism, to moderate and
equalize temperature, etc.
VIII. The physical and chemical properties

which have been taken into
consideration include nearly
all those which are known to

THE ARGUMENT 271

be of biological importance
or which appear to be related
to complexity, regulation, and
metabolism.

IX. There are no other compounds which

share more than a small part
of the qualities of fitness of
water and carbonic acid ; no
other elements which share
those of carbon, hydrogen, and
oxygen.
X. None of the characteristics of these

substances is known to be
unfit, or seriously inferior to
the same characteristic in any
other substance.

XI. Therefore the fitness of the environ-
ment is both real and unique.

In drawing this final conclusion I mean to
assert the following propositions: —

I. The fitness of the environment is one
part of a reciprocal relationship of which the
fitness of the organism is the other. This
relationship is completely and perfectly recip-
rocal; J the one fitness is not less important

1 This is not to be understood as an assertion that the rela-
tionship is symmetrical. The fad is that each uranism fits
its particular environment, while tli«- environment in its moat
general and universal characteristics fits the meal general and
universal characteristics of the organic mechanism.

272 THE FITNESS OF THE ENVIRONMENT

than the other, nor less invariably a constitu-
ent of a particular case of biological fitness;
it is not less frequently evident in the char-
acteristics of water, carbonic acid, and the
compounds of carbon, hydrogen, and oxygen
than is fitness from adaptation in the char-
acteristics of the organism.

II. The fitness of the environment results
from characteristics which constitute a series
of maxima — unique or nearly unique prop-
erties of water, carbonic acid, the compounds
of carbon, hydrogen, and oxygen and the
ocean — so numerous, so varied, so nearly
complete among all things which are concerned
in the problem that together they form cer-
tainly the greatest possible fitness. No other
environment consisting of primary constitu-
ents made up of other known elements, or
lacking water and carbonic acid, could possess
a like number of fit characteristics or such
highly fit characteristics, or in any manner
such great fitness to promote complexity,
durability, and active metabolism in the organic
mechanism which we call life.

It must not be forgotten that the possibility
of such conclusions depends upon the universal
character of physics and chemistry. Out of
the properties of universal matter and the
characteristics of universal energy has arisen

THE ARGUMENT 073

mechanism, as the expression of physico-
chemical activity and the instrument of physico-
chemical performance. Given matter, energy,

and the resulting necessity thai life shall be
a mechanism, the conclusion follows that the
atmosphere of solid bodies docs actually pro-
vide the best of all possible environments for
life.

CHAPTER VIII
LIFE AND THE COSMOS

THE SIGNIFICANCE OF FITNESS

A HALF century has passed since Darwin
wrote "The Origin of Species," and once
again, but with a new aspect, the relation
between life and the environment presents
itself as an unexplained phenomenon. The
problem is now far different from what it was
before, for adaptation has won a secure posi-
tion among the greatest of natural processes,
a position from which we may suppose it is
certainly never to be dislodged ; and natural
selection is its instrument, even if, as many
think, not the only one.1 Yet natural selec-

1 Natural selection remains still a vera causa in the origin
of species; but the function ascribed to it is practically
reversed. It exchanges its former supremacy as the supposed
sole determinant among practically indefinite possibilities
of structure and function, for the more modest position of
simply accelerating, retarding, or terminating the process of
otherwise determined change. It furnishes the brake rather
than the steam or the rails for the journey of life ; or in better

274

LIFE AND THE COSMOS

tion does but mold the organism ; the environ-
ment it changes only secondarily, without

truly altering the primary quality of environ-
mental fitness. This latter component of fit-
ness, antecedent to adaptations, a natural
result of the properties of matter and tli<"
characteristics of energy in the course of
cosmic evolution, is as yet nowise accounted
for. It exists, however, and must not be
dismissed as gross contingency. The mind
balks at such a view. Coincidences so nu-
merous and so remarkable as those which
we have met in examining the properties of
matter as they are related to life, must be the

metaphor, instead of guiding the ramifications of the tree
of life, it would, in Mivart's excellent phrase, do little more
than apply the pruning knife to them. In other words, its
functions are mainly those of the third Fate, not the first, of
Siva, not of Brahma. — Patrick Geddes and J. Arthttb
Thomson, 'Evolution." New York, Home University I.i
brary, 1911, p. 248.

"But as my conclusions have lately been much misrep-
resented, and it has been stated that 1 attribute the modifica-
tion of species exclusively to natural selection, I may be
permitted to remark that in the first edition <»f this work,
and subsequently, I placed in a most conspicuous position —
namely, at the close of the Introduction — the following
words: 'I am convinced that natural selection has been the
main but not the exclusive means of modification."
Charles Darwin, "The Origin of Species by Means of
Natural Selection." New York, reprinted from the Sixth
London Edition, The Home Library, pp. 495-496.

276 THE FITNESS OF THE ENVIRONMENT

orderly results of law, or else we shall have to
turn them over to final causes ! and the phi-
losopher.

There is, in truth, not one chance in count-
less millions of millions that the many unique
properties of carbon, hydrogen, and oxygen,
and especially of their stable compounds
water and carbonic acid, which chiefly make
up the atmosphere of a new planet, should
simultaneously occur in the three elements
otherwise than through the operation of a
natural law which somehow connects them
together. There is no greater probability
that these unique properties should be with-
out due cause uniquely favorable to the
organic mechanism. These are no mere acci-
dents ; an explanation is to seek. It must be
admitted, however, that no explanation is at

hand.

For the coincidence of properties itself a
rational explanation based upon known laws
of nature is perhaps conceivable. Attention
has already been called to the interconnection
of such properties as latent heat of vaporiza-
tion, thermal conductivity, molecular vol-
ume, the value of the van der Waals constant a,

1 Bacon compared final causes to vestal virgins. "Like
them," he says, "they are dedicated to God, and are barren."
— "The Advancement of Learning," Book II, p. 142.

LIFE AND THE COSMOS 077

the dielectric constant, and ionizing power.

Further, it is of course most probable that
numerous other properties are necessarily

associated with these; and finally it is nol
surprising that elements of low atomic weight,
which become concentrated in the atmos-
phere on account of the small specific gravity
of their gases, should possess unusual proper-
ties, like high specific heat, or if one property
leads to another, many unusual properties.
Be that as it may, chemical science is still
a very long way from accounting for the simul-
taneous occurrence of the various character-
istics of water, especially if we include such
things as heat of formation, solvent power,
the process of hydrolytic cleavage, the degree
of solubility of carbon dioxide, the anomalous
expansion on cooling near the freezing point,
etc.

There is, in fact, exceedingly little ground
for hope that any single explanation of these
coincidences can arise from current hypotheses
and laws. But if to the coincidence of the
unique properties of water we add that of the
chemical properties of the three elements, a
problem results under which the science of
to-day must surely break down. If these
taken as a whole are ever to be understood, it
will be in the future, when research has pene-

278 THE FITNESS OF THE ENVIRONMENT

trated far deeper into the riddle of the prop-
erties of matter. Nevertheless an explana-
tion cognate with known laws is conceivable,
and in the light of experience it would be
folly to think it impossible or even improbable.

Such an explanation once attained might,
however, avail the biologist little; for a
further problem, apparently more difficult, re-
mains. How does it come about that each and
all of these many unique properties should
be favorable to the organic mechanism, should
fit the universe for life ? And for the answer
to this question existing knowledge provides,
I believe, no clew.1

Thus regarded, our new form of the old
riddle appears twofold, and, on that account,
for the present the more unanswerable. There
is but one immediate compensation for this
complexity ; a proof that somehow, beneath
adaptations, peculiar and unsuspected relation-
ships exist between the properties of matter
and the phenomena of life; that the process
of cosmic evolution is indissolubly linked
with the fundamental characteristics of the
organism; that logically, in some obscure

1 The great difficulty appears to be that there is here no
possibility of interaction. In our solar system, at least, the
fitness of the environment far precedes the existence of the
living organisms.

LIFE AND THE COSMOS 27Q

manner, cosmic and biological evolution are
one. In short, we appear to be led to t he
assumption that the genetic or evolutionary
processes, both cosmic and biological, when
considered in certain aspects, constitute a
single orderly development thai yields results
not merely contingent, but resembling those
which in human action we recognize as pur-
poseful. For, undeniably, two things which
are related together in a complex manner by
reciprocal fitness make up in a very real sense
a unit, — something quite different from the
two alone, or the sum of the two, or the re-
lationship between the two.1 In human af-
fairs such a unit arises only from the effective
operation of purpose.

Now it is most clearly evident from the
experience of centuries that ordinary teleoloirv
is dangerous doctrine in science, and in the
past, accidents apart, it has been invariably
sterile.2 A statement that the legs have
been formed for the purpose of locomotion,
no doubt possesses scientific validity, if it be
properly interpreted. But the real scientific
concern is for the bones and muscles, the

1 This appears logically to correspond with the "schOp-
ferische Synthese" of Wuixlt.

2 Interesting discussions bearing upon flu's lubjed will
be found in Pearson's well-known "Grammar of Science."

280 THE FITNESS OF THE ENVIRONMENT

tendons and ligaments which are employed
in walking, and for the evolutionary process
by which they have been adapted to their use.
Nevertheless, biological science has not been
able to escape the recognition of a natural
formative tendency, which Darwin identified
as the result of natural selection. And now
it appears to be necessary to postulate a like
tendency in the evolution of inorganic nature.
We have found that the properties of the
environment, biologically considered, present
the same fitness as the properties of life. In
each case the fitness results, at least in part,
from an evolutionary process. Through the
main lines of later development these are
both known, though in both cases we stop
short, perhaps far short, of the origins — the
origin of life and the origin of the universe —
if indeed they have ever originated.1 Can
we then deny that in the one as in the other
process there is a tendency, a bent, a direc-
tion of flow or development?2 I think not,

1 It is hardly necessary to point out that the properties
of the elements are themselves quite free from variation of
any sort.

2 "Alike in the external and the internal worlds, the man of
science sees himself in the midst of perpetual changes of which
he can discover neither the beginning nor the end. If, trac-
ing back the evolution of things, he allows himself to enter-
tain the hypothesis that the universe once existed in a dif-

LIFE AND THE COSMOS Si

and it seems clear thai the facts of physical
science call for an explanation of the tend-
ency to fitness of the environment in the
same way that formerly the facts of biologi-
cal science called for an explanation of the
tendency to fitness of the organism.

To postulate such a tendency is, however,
in itself rather a philosophical than a scientific
act, and so, too, must he conjecture regarding
the origin of fitness. It is open to any one
who may be so minded speculatively to enrich
this tendency with characteristics of any sort.
He may follow the lead of M. Bergson and
call it impetus, with all which that term now
implies, or he may turn to natural theology
and regard it as proof of supernatural purpose
and design, or he may find a model for teleolog-
ical views in many other quarters. But one
thing is certain, no such discussion, be it ever
so important to the philosopher or the theo-
logian, can directly contribute to scientific
knowledge and comprehension of the under-
lying phenomena, which arc the sole positive
and certain knowledge of the subject that

fused form, he finds it utterly impossible to conceive how this
came to !><■ bo; and equally, if he speculates on tin- rutu
he can assign no limit to the L,rrand succession of phenomena
ever unfolding themselves before him.*' Herbert Spbn< nt,
"First Principles." Ww York, reprinted from the Fifth
Loudon Edition, 1880. The Home Library, j>. 57.

282 THE FITNESS OF THE ENVIRONMENT

we possess. For these facts an explanation of
a different sort would be necessary, some-
thing logically resembling natural selection,
a natural process acting automatically through
the properties of matter and energy, and
never overstepping the limits of matter and
energy, space and time; neither supernatural
nor metaphysical, but purely mechanistic.
Lacking any indication of what such an expla-
nation may be, or how it is to be sought, we
shall do well to turn to other considerations.

n

VITALISM

All the skill of trained biologists, multi-
plying and refining our knowledge of the
forms of life, has even yet not availed to make
clear the fundamental ideas of the science.
Complexity exists here in the very nature
of the case, and here, if at all, the complete
subjugation of natural phenomena to physi-
cal science may be expected to fail.

In an earlier chapter the painful advance of
physics and chemistry into the domain of
biology has been sketched, and it was then
shown how progress is beset with well-nigh
insuperable obstacles. Thus it is that bio-
logical thought has never attained to that

LIFE AND THE COSMOS &9

finality which appears, at least by contrast,
to characterize the greater body of opinions
in physical science.

In particular two extreme views, though

often commingled, have continually striven
for the mastery. The one of these, purely
scientific and wholly positive, declares the
phenomena of life to be, while partly unknown,
ultimately knowable as manifestations of
matter and energy. According to this view
life is a mechanism and nothing more, in its
positive scientific aspects at least. Without
necessarily denying such assertions, the
other view sees the unique properties of life
to be dependent upon an equally unique
force or tendency, operating in or through
its physico-chemical organization. Either
there is a peculiar vital force; or there is
manifest in the organism a peculiar tendency ;
or at any rate life patently follows the path
into which it was propelled by an original
impetus, peculiar to life, unknown in other
phenomena. All such views inherently par-
take of metaphysics, and have, therefore,
ever aroused most determined opposition
among the more orthodox devotees of science.
Descartes appears to have been the first
person to adopt the modern scientific attitude
toward life, and from him a very large pro-

284 THE FITNESS OF THE ENVIRONMENT

portion of French biologists, as well as those
of other nations like Huxley and Du Bois-
Reymond, derive their philosophical views
concerning their science. Descartes per-
ceived, apparently the first among the mod-
erns, that the scientific explanation of vital
phenomena must be a physical one, in terms
of matter and motion. Far in advance of
his time he applied such ideas to the nervous
system, thereby establishing the nature of
reflex action and invading the very citadel
of animism. Outside natural science, how-
ever, Descartes was far from being a mechan-
ist. Since the early seventeenth century the
conflict between vitalism and mechanism
has ranged over the whole field of biology, and
its history is most complicated. After Des-
cartes, Lavoisier, by his studies of combustion
within and without the body, made the next
very important step. He was then followed
by Liebig, Wohler, and a host of later chem-
ists.

In the main the growth of exact science has
steadily delivered over one vitalistic strong-
hold after another to the mechanists. And
though in the first flush of triumph mechan-
ism has sometimes seemed to gain more in a
particular engagement than later proved to
be the case, vitalism has perhaps not had a

LIFE AND HIE COSMOS 285

positive success in three centuries. Such a
history no doubt depends upon the very na-
ture of the situation; upon the inherent and
inevitable weakness, within the domain of

science, of vital istic views.

Experience seems to show that the only kind
of hypothesis which can find conclusive scien-
tific support, or sound basis in the phenomena
of matter and energy, is a mechanistic hy-
pothesis. Exact and positive knowledge can
demonstrate scientifically the truth of no
other hypothesis with the finality which char-
acterizes its proof of a mechanistic theory.
Hence, so far as it ventures into the field of
science at all, a vitalistic theory, when attacked
by science, cannot effectually avail itself of
the weapons of the assailant, and can never
make a powerful counter attack. Its only
method consists in a determined resistance,
yielding little by little before the advance of
positive knowledge and never gaining new
territory, nor, except by accident, regaining
what it has lost. Where this process is to
end; in what respect and how far life is des-
tined ever to remain a scientific riddle, can
only be surmised.

The chief definitive triumphs of the mech-
anistic view are two: the elimination of vital
force and of a belief in peculiarity of chemical

286 THE FITNESS OF THE ENVIRONMENT

composition from organic chemistry, through
the actual successes of the laboratory in new
syntheses; and the final recognition, based
upon understanding of the principle of the
conservation of energy, that, whatever else
"vital force" may be, it is certainly not
force, — a form of energy. Thus limited,
vitalism has been obliged to take refuge in a
more restricted belief; namely, that the organ-
ism is somehow governed by a directive
tendency which, like an architect, presides
over its development ; but that meanwhile the
manifold processes of life and evolution go on
within the world of physical science just as
the work of the builder conforms to the laws
of mechanics, though following the plan of the
architect.

This view has been well stated by another
great Frenchman, Claude Bernard: "Life
is the directive idea or evolutive force of the
being ; . . . but it would be an error to believe
that this metaphysical force operates after
the manner of a physical force. . . . The
metaphysical evolutive force by which we
may characterize life is useless to science,
because, existing apart from physical forces,
it can exercise no influence upon them. Hence
we must here separate the world of meta-
physics from the world of positive phenomena

LIFE AND THE COSMOS 287

which serves it as foundation, but which has
nothing to contribute to it. . . . Summaris-
ing, if we can define life with the help of a
special metaphysical conception, it is none
the less true that mechanical, physical, and
chemical forces are the sole effective agents of
the living organism, and that the physiologist
has to take account of their action alone. We
shall say with Descartes, 'One thinks meta-
physically, but one lives and acts physically.' ]
Thus restricted, vitalism can apply only to
formative processes and the like, though the
vitalist still sees in the state of the organism

1 "Claude Bernard, 'La Science Experimentale,' 3me <■<!..
p. 211 : 'La vie est l'idee directrice ou la force evolutive de
1'etre ; . . . mais l'erreur serait de croire que cette force meta-
physique est active a la facon d'une force physique. ... La
force metaphysique evolutive par laquellc nous pouvons
caracteriser la vie est inutile a la science, parce qifetant en
dehors des forces physiques elle ne peut exercer aucune in-
fluence sur elles. II faut done ici separer le monde inrtaphy-
sique du monde physique phenomenal qui lui sert de bat
mais qui n'a rien a lui emprunter. . . . En resume, si QOUI
pouvons definir la vie a l'aide d'une conception metaphyaique
speciale, il n'en reste pas moins vrai que les forces ni« < a
niques, physiques, et chimiques, sont seules les agents effectifs
de l'organisme vivant et que le physiologiste ne peut avoir I
tenir compte que de leur action. Nous dirons avec 1 )«■>< art
on pense metaphysiquement, mais on vit et on agit physique-
ment.'" — Merz, "A History of European Thought in the
Nineteenth Century." Edinburgh and London. L906, Vol.
II, pp. 379-380.

288 THE FITNESS OF THE ENVIRONMENT

effects of vitalistic control of its evolution,
just as we perceive in a house not only the
material structure, but the idea of the archi-
tect. Further, the origin of life itself remains
shrouded in mystery. Meanwhile, for most
men physiology has become merely biophys-
ics and biochemistry, and mechanism is un-
doubtedly firmly established throughout every
department of the science.

Such limitations of the vitalistic hypothesis,
damaging though they may be, do not de-
stroy its claim to consideration as a controlling
factor of the processes of evolution, embry-
ology, repair, etc., in spite of the fact that
even here it has suffered serious though less
complete reverses. In 1859 Darwin's natural
selection offered itself as a possible substi-
tute for vitalism in a part or the whole of this
field, and soon gained very general accept-
ance. The survival of the fittest has now
become in the judgment of all biologists an
unquestioned force in the molding of life.
Therefore, at best, but a restricted scope
within its restricted field remains to vital-
ism.

From the earliest days of the new hypothesis
it has been widely recognized that to accept
the survival of the fittest as one factor in the
adaptation of life to its environment is quite

LIFE AND THE COSMOS ^S9

a different matter from proving il to be the
only force which directs evolution. An early

eulogy by Du Bois-Reymond upon the work
of Darwin clearly discloses the nature of the
situation: 'Here is the knot, here the great
difficulty that tortures the intellect which
would understand the world. Whoever does
not place all activity wholesale under the sway
of Epicurean chance, whoever gives only his
little finger to teleology, will inevitably arrive
at Paley's discarded 'Natural Theology,' and
so much the more necessarily, the more
clearly he thinks and the more independent
his judgment . . . the physiologist may define
his science as a doctrine of the changes which
take place in organisms from internal causes.
. . . No sooner has he, so to speak, turned
his back on himself than he discovers himself
talking again of functions, performances, ac-
tions, and purposes of the organs. The possi-
bility, ever so distant, of banishing from na-
ture its seeming purpose, and putting a blind
necessity everywhere in the place of final
causes, appears, therefore, as one of the
greatest advances in the world of thought,
from which a new era will be dated in the
treatment of these problems. To have some-
what eased the torture of the intellect which
ponders over the world-problem will, as long

u

290 THE FITNESS OF THE ENVIRONMENT

as philosophical naturalists exist, be Charles
Darwin's greatest title to glory." 1

Recently the work of de Vries, "The Muta-
tion Theory," has at length set forth a num-
ber of trustworthy observations of the origin
of species in plants with which natural selec-
tion, in the restricted original sense at least,
can have nothing to do. The origin of species
by mutation consists in a sudden discontinu-
ous variation, and selection, therefore, has
no opportunity to operate upon a series of
numerous minute variations which them-
selves display no tendency of any sort what-
ever, in the manner demanded by the Darwin-
ian hypothesis.2 Hence it appears certain
that natural selection cannot be regarded as
completely master of the situation; apart
from the origin of life there remains a lacuna
in biology which for the present no existing
mechanistic hypothesis can fill.

Moreover, among other things, the ordinary
processes of regeneration and repair have
frequently been brought forward with some
success as purposeful activities inexplicable

1 Du Bois-Reymond, "Darwin versus Galiani," "Reden,"
Vol. I, p. 211. Quoted from Merz, "History of European
Thought in the Nineteenth Century," Vol. II, p. 435. To
the same source I am indebted for several other quotations.

2 Hugo de Vries, "The Mutation Theory." Chicago, 2
vols., 1909, 1910 (trans. Farmer and Darbishire).

LIFE AND THE COSMOS 29]

by natural selection.1 Tims Du Bois-Rey-
mond: "One of the greatest difficulties pre-
sents itself in physiology in the so-called re-
generative power, and — what is allied to it

— the natural power of healing; {his may now
be seen in the healing of wounds, in the delim-
itation and compensation of morbid processes

or, at the farthest end of the series, in the
re-formation of an entire fresh-water polyp
out of one of the two halves into which it had
been divided. This artifice could surely not
have been learned by natural selection, and
here it appears impossible to avoid the assump-

1 "Still less explicable in any way thus far proposed are
certain remedial actions seen in animals. An example of
them was furnished in §67, where 'false joints' were de-
scribed — joints formed at places where the ends of a brok. n
bone, failing to unite, remain movable one upon the other.
According to the character of the habitual motions there re-
sults a rudely formed hinge-joint or a ball-and-socket joint,
either having the various constituent parts — periosteum,
fibrous tissue, capsule, ligaments. Now Darwin's hypothesis,
contemplating only normal structures, fails to account for
this formation of an abnormal structure. Neither can we
ascribe this local development to determinants: there were
no appropriate ones in the germ-plasm, since no such struc-
ture was provided for. Xor does the hypothesis of phil-
ological units, as presented in preceding chapters, yield an
interpretation. These could have qo other tendency than to
restore the normal form of the limb, and mighl be expected
to oppose the genesis of these new parts." — HsBBBBT
Spencer, "The Principles of Biology," Vol. I. New York
and London, 1909, revised and enlarged edition, p. :><iJ.

292 THE FITNESS OF THE ENVIRONMENT

tion of formative laws acting for a purpose.
They do not become more intelligible by the
fact that the regeneration of mutilated crys-
tals, observed by Pasteur and others, points
to similar processes in inanimate nature.
Also the ability of organisms to perfect them-
selves by exercise has not found sufficient
appreciation with regard to natural selec-
tion." 1

To sum up, it appears certain that at least
in a few instances, and possibly quite generally,
purposeful tendencies exist in the organism
which seem to be inexplicable by natural selec-
tion or any other existing mechanistic hypoth-
esis. It is not too much to hope that a scien-
tific explanation of these phenomena in whole
or in part may some day be found ; but mean-
time they constitute the natural subject
of vitalistic speculation. A field remains,
though limited, where the physical scientist
cannot yet successfully subdue the vitalist,
however strong his conviction of the errors of
vitalism.2

1 Du Bois-Reymond, "Reden," Vol. I, p. 226.

2 The indeterminism which is based uniquely upon belief
in freedom of the will appears to be foreign to the present dis-
cussion. It is, accordingly, entirely disregarded in the follow-
ing considerations. Hence the conclusions of the present in-
quiry are not to be taken as cognate with such metaphysical
hypotheses as the indeterminism of Kant and Lotze.

LIFE AND THE COSMOS

Vitalism therefore flourishes, as the recent
remarkable works of Driesch and Bergson tes-
tify. Of tlicse two authors the former is
concerned to prove that pure mechanism is
insufficient in biology, and that to mechanism
must be added his entelechies ; ] the latter
has gone beyond the vitalism of earlier au-
thors, to give his own view of his speculations,
and introduced the idea of the vital impetus.

A

THE VITALISM OF BERGSOX

Upon analysis the theory of Bergson
amounts to this, that there is an original
creative impetus impelled upon life which, at
all events in the main, is responsible for the
course that organic evolution has taken.
To quote his own words: "So we come back,
by a somewhat roundabout way, to the idea
we started from, that of an original impetus
of life, passing from one generation of germs
to the following generation of germs through
the developed organisms which bridge the
interval between the generations. This im-
petus, sustained right along the lines of evo-
lution among which it gets divided, is the
fundamental cause of variations, at least

1 Driesch, "The Science and Philosophy of the Organism."
London, 1907 and 1908, two volumes.

294 THE FITNESS OF THE ENVIRONMENT

of those that are regularly passed on, that
accumulate and create new species. In gen-
eral, when species have begun to diverge from
a common stock, they accentuate their diver-
gence as they progress in their evolution.
Yet, in certain definite points, they may
evolve identically ; in fact, they must do so
if the hypothesis of a common impetus be
accepted. This is just what we shall have to
show now in a more precise way, by the same
example we have chosen, the formation of
the eye in molluscs and vetebrates. The idea
of an 'original impetus,' moreover, will thus
be made clearer." 1 . . . "If life realizes
a plan, it ought to manifest a greater harmony
the further it advances, just as the house
shows better and better the idea of the archi-
tect as stone is set upon stone. If, on the
contrary, the unity of life is to be found solely
in the impetus that pushes it along the road of
time, the harmony is not in front, but behind.
The unity is derived from a vis a tergo: it
is given at the start as an impulsion, not
placed at the end as an attraction. In com-
municating itself, the impetus splits up more
and more. Life, in proportion to its progress,
is scattered in manifestations which un-

1 Bergson, "Creative Evolution," translated by Mitchell.
New York, 1911, pp. 87, 88.

LIFE AND THE COSMOS

doubtedly owe to their common origin the
fact that they are complementary to each other
in certain aspects, but which are none the less
mutually incompatible and antagonistic." ■

The contention of Bergson may be divided
into two parts: a statement of belief in an
original impetus, and his biological argu-
ments in favor of such a view. The former,
in so far as it is a question exclusively of an
original impetus, appears to lie outside the
scope of science, in company with speculations
upon the origin of the universe; the latter,
because it deals with the subject-matter of
science, is open to scientific criticism, and from
the standpoint of the biologist is certainly
far from conclusive.2

Bergson's hypothesis is, however, in es-
sence not less vitalistic than that of Driescli.
Both philosophers assume the existence of a
special vital characteristic, and explain the
course which evolution has taken as a result
of it. In short, modern vitalism consist^
in postulating a directive tendency which
manifests itself in or through the organism
alone, and is peculiar to life.

1 Ibid., p. 103.

2 In fact, until the mechanistic operation «>f Bergson'a
impetus can be clearly perceived, it must remain scientifically
an unsound hypothesis.

296 THE FITNESS OF THE ENVIRONMENT

In such speculations the properties of
matter and the process of cosmic evolution
have no place.1 Bergson, indeed, very defi-
nitely, and it would seem gratuitously, puts
aside cosmic evolution and also, with certain
slight reservations, the properties of matter as
of no essential consequence in organic evolu-
tion; e.g. "This twofold result has been ob-
tained in a particular way on our planet. But
it might have been obtained by entirely dif-
ferent means. It was not necessary that life
should fix its choice mainly upon the carbon
of carbonic acid. What was essential for it
was to store solar energy ; but, instead of ask-
ing the sun to separate, for instance, atoms of
oxygen and carbon, it might (theoretically
at least, and, apart from practical difficulties

1 Driesch, to be sure, has considered the problem of uni-
versal teleology, but unsuccessfully and with obvious vitalistic
preconceptions such as individuality. His nearest approach
to the thesis of the present work is to be found in the follow-
ing lines: "I do not hesitate to confess that, apart from
historical teleology relating to the sequence of one state of poli-
tics or economy upon another, and apart from phylogeny,
there seems to me to be a certain sound foundation in the
concept of the general harmony between organic and inor-
ganic nature, a something which seems to show that nature
is nature for a certain purpose. But I confess at the same time
that I am absolutely unable to consider this purpose in
any other than a purely anthropomorphic manner." — L.c,
Vol. II, pp. 348-349.

LIFE AND Till: COSMOS

possibly insurmountable) have put forth otln r

chemical elements, which would then have had
to be associated or dissociated 1>\* entirely dif-
ferent physical means. And if the element
characteristic of the substances that supply

energy to the organism had been oilier than
carbon, the element characteristic of the

plastic substances would probably have been
other than nitrogen, and the chemistry of
living bodies would then have been radically
different from what it is. The result would
have been living forms without any analogy
to those we know, whose anatomy would have
been different, whose physiology also would
have been different. Alone, the sensori-motor
function would have been preserved, if not its
mechanism, at least in its effects. It is there-
fore probable that life goes on in other planets,
in other solar systems also, under forms of
which we have no idea, in physical conditions
to which it seems to us, from the point of
view of our physiology, to be absolutely op-
posed. If its essential aim is to eat eh up
usable energy in order to expend it in explo-
sive actions, it probably chooses, in each
solar system and on each planet, as it does
on the earth, the fittest means to get this
result in the circumstances with which it i^
confronted. That is at least what reasoning

298 THE FITNESS OF THE ENVIRONMENT

by analogy leads to, and we use analogy the
wrong way when we declare life to be impos-
sible wherever the circumstances with which
it is confronted are other than those on the
earth. The truth is that life is possible wher-
ever energy descends the incline indicated by
Carnot's law and where a cause of inverse
direction can retard the descent — that is to
say, probably, in all the worlds suspended
from all the stars. We go further : it is not
even necessary that life should be concen-
trated and determined in organisms properly
so called, that is, in definite bodies present-
ing to the flow of energy ready-made though
elastic canals. It can be conceived (although
it can hardly be imagined) that energy might
be saved up, and then expended on varying
lines running across a matter not yet solidified.
Every essential of life would still be there,
since there would still be slow accumulation
of energy and sudden release." *

B

VITALISM AND TELEOLOGY

These conclusions appear to be based upon
decisions regarding the essential physico-chem-
ical conditions and characteristics of life arbi-

1 Bergson, l.c.y pp. %55, 256.

LIFE AND THE COSMOS

trarily reached in accordance with precon-
ceived views, and quite without scientific
justification. There is certainly no reason
to ascribe greater importance to energy than

to matter in the vital processes, and in the
light of the facts with which the preceding
chapters are concerned, such views seem
absurd. Indeed, whoever is disposed to spec-
ulate about biological fitness — and not even
the incomparable finesse of M. Bergson's dia-
lectic can make fitness other than the most
general result of the process of organic evolu-
tion— must now weigh well the cosmic pro-
cesses. For, if allowance be made for the
results of natural selection in the organic
world, fitness of the environment has the
greater claim to be considered.

The two fitnesses are complementary; are
they then single or dual in origin ? The simple
view would be to imagine one common impe-
tus operating upon all matter, inorganic and
organic, through all stages of its evolution,
in all its states and forms, and leading to
worlds like our own through paths apparently
purposeful and really not yet explained.
Such, it seems to me, is the natural hypothesis
for the vitalist to adopt. But then vitalism
vanishes, only teleology remains; for the
unique characteristic of life is gone. Vet,

300 THE FITNESS OF THE ENVIRONMENT

putting aside mechanistic differences, is it not
now lost in any case ? Has not modern vital-
ism in accepting the limitation to entelechies
or impetus destroyed itself ?

The situation, briefly, seems to be as fol-
lows : two evolutionary processes independ-
ently result in two complementary fitnesses;
hence they are related. In the one process
the origin of fitness is in part explained by a
mechanistic hypothesis. Nevertheless, many
philosophers, as is their right, declare that in
this process a further extraphysical influence
is to be assumed. But any one who makes
such an assumption for the one process must
certainly now make it for the other; thus he
will be led to see impetus or entelechies every-
where. Under these circumstances it may
be doubted if his acquaintance with the na-
ture of his impetus or entelechies is so inti-
mate that he will be able to distinguish the
inorganic from the organic, for he has surren-
dered to science all the positive physico-chem-
ical differences between organic and inorganic
bodies and processes. Hence, unless he is to
make an arbitrary and unintelligible distinc-
tion, or to indulge in the spinning of cob-
webs, his vitalism has ceased to be exclusively
organic, in short has ceased to be vitalism at
all, and has become mere universal teleology.

LIFE AND THE COSMOS 301

III

COSMIC EVOLUTION

But, for the scientist, these are matters
of little moment, lie, at least, is not obliged

to take any stand concerning them. This
could hardly be better illustrated than by our
new facts themselves. For it seems to be
clear that where science is most self-sufficient,
at the very basis of physical science itself,
if anyiohere, teleology is at work. Yet it is
certain that physical science needs no tele-
ology to explain its phenomena and pro-
cesses. These are mechanisms, and since
the publication of Newton's "Principia" no
one has seriously doubted the fact.1

To-day there is as little room for doubt thai
a complete description of cosmic evolution in
terms of matter and energy is possible; for
it is sound scientific doctrine that what exists
in the finished solar system depends upon
what already existed in the nebula. The
forms and states and quantities of matter
and energy in the nebula determine the re-
sulting solar system. Further, since both
nebulae and solar systems are common oc-

1 Laplace's reply to a question of Napoleon's, "Why the
name of God did not occur in his ' Rlecanique Odette,' will
be recalled : "Sire, je n'ai pas besom de cet hypothei

302 THE FITNESS OF THE ENVIRONMENT

currences, it is evident that nebulae them-
selves are in a general way determined by
other antecedent conditions and phenomena,
which turn out to be collisions between stars.
Thus arises the suspicion that cosmic evolu-
tion may be in truth a cyclic process which
had no beginning and can have no end.1
An alternative hypothesis regards the pres-

1 Such a view, until quite recently, was universally rejected
because it appeared to conflict with the second law of thermo-
dynamics, — that of the degradation of energy. But lately it
has been put forth by no less an authority than Arrhenius,
who has advanced a theory to explain away the difficulty of
the second law.

"The recognition of the indestructibility of energy
seemed to accentuate the difficulties of the cosmogonic prob-
lems. The theses of Mayer and of Helmholtz, on the man-
ner in which the Sun replenished its losses of heat, have had
to be abandoned. My explanation is based upon chemical
reactions in the interior of the Sun in accordance with the
second law of thermodynamics. The theory of the 'degra-
dation' of energy appeared to introduce a still greater diffi-
culty. That theory seems to lead to the inevitable conclu-
sion that the Universe is tending towards the state which
Clausius has designated as 'Warme Tod' (heat death), when
all the energy of the Universe will be uniformly distributed
through space in the shape of movements of the smallest
particles. That would imply an absolutely inconceivable
end of the development of the Universe. The way out of this
difficulty which I propose comes to this : the energy is * de-
graded' in bodies which are in the solar state, and the energy
is 'elevated,' raised to a higher level, in bodies which are in
the nebular state." — Arrhenius, "Worlds in the Making,"
translated by Boras. New York and London, 1908, p. xiii.

LIFE AND THE COSMOS 303

ent form of our universe as the result of a

gradual evolution from an earlier unknown
form, the development of successive solar
systems being mere incidents of the larger
process, the evolution as a whole directively

governed by the law of the degradation of
energy.

A

THE PERIODIC SYSTEM

In either hypothesis the remarkable sys-
tematic relationship between the elements
which is manifest in the periodic classifica-
tion has a peculiar place. If the second hy-
pothesis be accepted, there seems to be little
room for doubt that at an early period the
chief cosmic process wras the evolution of the
elements themselves; and in the first theory
the nebula, wdiose properties depend almost
wholly upon chemical constitution and chem-
ical and molecular energy, occupies a unique
position, like the leaf in the organic cycle,
or spring among the seasons. Thus, whether
or not the periodic system is to be regarded
as the one remaining plain result of a process
bv which the elements were evolved, at leas!
it takes precedence over the other properties
of matter, and lies at the very foundation of
the known processes of evolution. Clearly,

304 THE FITNESS OF THE ENVIRONMENT

no one can doubt that upon the properties
of matter as determined by the periodic
system, and upon the relative amounts of the
different elements, the actual process of cos-
mic evolution from nebula to solar system
is dependent.1

Hence, in accordance with the general
method of science, we must assume that the
origin of environmental fitness lies at least
as far back as the phenomena of the periodic
system, at least as far back as the evolution
of the elements, if they were ever evolved.
We simply cannot doubt that the origin of a
body like the earth depends exclusively upon
chance plus the properties of the elements,
their relative amounts, the indestructible
forces of nature, and the other known factors
of mechanism. The perfect induction of phys-
ical science, based upon each and all of its
countless successes in every department of
physics and chemistry, conclusively proves
that the whole process of cosmic evolution
from its earliest conceivable state to the pres-
ent is pure mechanism.2

1 The same considerations apply to any other scientific
hypothesis of the genesis of the solar system.

2 Not only is this proved by all experience of physical
science, it has also ever been the necessary working hypoth-
esis of physicists and chemists.

LIFE and THE COSMOS 805

B

TKU.nl ni;v

If, then, cosmic evolution be pure mechan-
ism and yet issue in fitness, why imi organic
evolution as well? Mechanism is enough
in physical science, which no less than bioloj
ical science appears to manifesl teleology;
it must therefore suffice in biology.

Thus once more we arrive a1 the negation of
vitalism. For this conclusion we possi
two arguments: the argumenl that in such
aspects as concern physical science, and apart
from differences scientifically explicable, or-
ganic and inorganic phenomena arc alike and
therefore a specifically vital teleology is un-
necessary; and the argument thai inorganic
science unquestionably has no need of non-
mechanistic teleology. Hence we are obliged
to conclude that all metaphysical teleology is
to be banished from the whole domain of
natural science.1

What then becomes of fitness? Clearly
there are two logical possibilities. Either there
exists an unknown mechanistic explanation of
that common issue of the organic and cosmic

1 Such at least is the simplest provisional hypothesis, :m<!
the only view which involves n.> gratuitous assumptions. It ii

therefore the one which must DOW !><• adopted.

306 THE FITNESS OF THE ENVIRONMENT

evolutionary processes, or there does not. If
such an explanation be possible, at least it
must be admitted that it is very hard to con-
ceive. Yet, recalling the difficulty before the
idea of natural selection arose of imagining any
mechanistic explanation whatever of fitness,
we shall do well not to decide against such a
possibility.

On the other hand, it is conceivable that a
tendency could work parallel with mechanism
without interfering with it, according to a
view which has been held by such thorough-
going mechanists as Descartes, Claude Ber-
nard, Virchow, DuBois-Reymond, and many
another. Although I have no intention of
here seeking a choice between these two hy-
potheses, being in fact convinced that now,
at all events, no choice is scientifically possi-
ble, and doubting if properly speaking they are
alternatives at all,1 I do feel concerned to

1 "Either the multitudinous kinds of organisms which now
exist, and the far more multitudinous kinds which have existed
during past geologic eras have been from time to time sep-
arately made, or they have arisen by insensible steps, through
actions such as we see habitually going on. Both hypotheses
imply a Cause. The last, certainly as much as the first,
recognizes this Cause as inscrutable. The point at issue is,
how this inscrutable Cause has worked in the production of
living forms. This point, if it is to be decided at all, is to be
decided only by examination of evidence. Let us inquire
which of these antagonistic hypotheses is most congruous

LIFE AND THE COSMOS 807

remove from the latter view, if I may, some <>f
the objections which are commonly raised
against it in scientific circles, conscious thai
in this attempt I am overstepping the bound-
aries of natural science.

It is evident that a perfect mechanistic
description of the building <>f a house may be
conceived. Within the world of physical
science the whole process is logically complete
without consideration of the architect's de-
sign and purpose. Yet such desij and
purpose, whether or not in themselves of
mechanistic origin, are at one and the same
time determining factors in the result, ;md
nowise components of the physical process.
Now it seems clear that a similar effect of a
tendency working steadily through the whole
process of evolution is also at least conceive-
able, however small its bearing upon science,
provided, like time itself, it be a perfectly
independent variable, making up. therefore,
with time the constant environment, so to
speak, of the evolutionary process. The tend-
ency must not be demonstrable either by
weighing or by measuring, else it would
amount to an interference within the mech-

with establish^! facts." — HSBBMBT SpENCBB, 'The Prin-
ciples of Biology." Men York And London, L909, V6L I.
revised and enlarged edition, p. 116.

308 THE FITNESS OF THE ENVIRONMENT

anistic process, and it must not be itself
liable to any kind of variation whose detec-
tion would directly reveal it. Where then
can the origin of such a tendency be located?
Why clearly, if we accept the induction in
favor of mechanism, only where Bergson has
shrewdly placed his vital impetus, at the very
origin of things, just before mechanism begins
to act. In short, our new teleology cannot
have originated in or through mechanism,
but it is a necessary and preestablished asso-
ciate of mechanism. Matter and energy have
an original property, assuredly not by chance,
which organizes the universe in space and
time.

This is in very truth a metaphysical doc-
trine; but it has strong claims to sympa-
thetic regard from men of science. In the
first place, it leaves mechanism with the
perfectly free hand which that process has
undoubtedly earned in the world of phe-
nomena. Secondly, it does but add one further
riddle, and that an old and familiar one, to
those two already tacitly recognized by most
scientists : the existence of the universe and
the existence of life. Given the universe, life,
and the tendency, mechanism is inductively
proved sufficient to account for all phenomena.

The existence of the universe, on the other

LIFE and thi: COSMOS

hand, is no concern of the scientist. What-
ever else it may achieve, mechanism can never
explain, cannot even face the problem of the
existence of matter and energy, Within the
world of science these are conserved; only
outside thai world can they have originated
or not originated. As for the existence of
life, in spite of our utter ignorance, if must
be admitted that a half century has greatly
diminished the number of substantial biolo-
gists who really look forward to its scientific
explanation, and the greatesl chemists have
ever shared such a view. Liebig is reported
by Lord Kelvin to have replied to the ques-
tion whether he believed that a leaf or a Bower
could be formed or could grow by chemical
forces, "I would more readily believe thai a
book on chemistry or on botany could grow
out of dead matter."1 Darwin, too, once
said, "It is mere rubbish tihinlrfng at present
of the origin of life; one might as well think
of the origin of matter."1 Since Liebig's
day the chemical organization of the cell lias
become in scientific knowledge vastly more
complex than it was before, and I know of DO
biological chemist to whom the spontaneous,

1 Lord Kelvin, "On the I)i>sipat ion of Energy," IV. ;.ii!ar
Lectures, Vol. III. p, 164.
2Merz, Vol. II. p. I 06.

310 THE FITNESS OF THE ENVIRONMENT

that is to say, the mechanistic, origin of a cell
is scientifically imaginable,1 though all believe
that once formed, cells exist as mechanisms
in a mechanistic universe.2 Thus the chem-
ist puts his mind at rest regarding the exist-
ence of life, just as the physicist calms his
regarding the existence of matter, simply by
turning his back on the problem. Thereby
he suffers nothing in his practical task as a
man of science.

Returning now to fitness, we may be sure
that, whatever successes science shall in future
celebrate within the domain of teleology, the
philosopher will never cease to perceive the
wonder of a universe which moves onward
from chaos to very perfect harmonies, and,
quite apart from any possible mechanistic

1 This is not to express an opinion concerning the problem
of abiogenesis ; all admit that we cannot disprove such a
theory. But while biophysicists like Professor Schafer follow
Spencer in assuming a gradual evolution of the organic from
the inorganic, biochemists are more than ever unable to per-
ceive how such a process is possible, and without taking any
final stand prefer to let the riddle rest. But if life has
originated by an evolutionary process from dead matter,
that is surely the crowning and most wonderful instance of
teleology in the whole universe.

2 See, for instance, F. Hofmeister, "Die Chemische Organ-
isation der Zelle," Vieweg, Brunswick, 1901, and Alsberg,
"Mechanisms of Cell Activity," Science, pp. 97-105, July 28,
1911.

LIFE AM) THE ( OSMOfi ! 1

explanation of origin and fulfillment, to feel it
a worthy subjecl of reflect ion. From t bis point
of view, however, science need i cf no inter-
ference, but without any lasl v< of former
shackles may pursue the search after mechan-
istic explanations of all natural phenomena

At length we have reached the conclusion
which I was concerned to establish. Science
has finally put the old teleology to death.
Its disembodied spirit, freed from vitalism
and all material ties, immortal, alone li\- -
on, and from such a ghost science has noth-
ing to fear. The man of science is not even
obliged to have an opinion concerning its
reality, for it dwells in another world where
he as scientist can never enter.

1 "An evolution is a series of events that in itself M M ri* ■
is purely physical, — a set of necessary occurrences in the
world of space and time. An egg develops into s chick;
a poet grows up from infancy; a nation emerges from bar-
barism; a planet condenses from the Quid state, and develops
the life that for millions of years makes it so prondrous s pin
Look upon all these things descriptively, and you shall -
nothing but matter moving instant after instant, each con-
taining in its full description the necessity of ps - into

the next. Nowhere will there be. for descriptive seien

any genuine novelty or any discontinuity admissible. Hut
look at the whole appreciatively, historically, synthetically,
as a musician listens to ■ symphony, as s
a drama. Now you shall seem to hs n. in phenoi

form, a story." — ROYCU, "The Spirit of Modern I'hilosoph;
Boston and New York, 1890, 8th ed., p. 1

312 THE FITNESS OF THE ENVIRONMENT

I cannot hope to have provided more than
a very imperfect illumination of certain as-
pects of teleology in this venture upon the
foreign field of metaphysics, and I should
wish to be understood as very doubtful of my
success in stating what seem to me some of
the philosophical conclusions to be drawn
from the fitness of the environment.

There is, however, one scientific conclusion
which I wish to put forward as a positive and,
I trust, fruitful outcome of the present
investigation. The properties of matter and
the course of cosmic evolution are now seen
to be intimately related to the structure of
the living being and to its activities; they
become, therefore, far more important in
biology than has been previously suspected.
For the whole evolutionary process, both cos-
mic and organic, is one, and the biologist may
now rightly regard the universe in its very
essence as biocentric.

jam/an xaauww

PKOPERTT LMAST

K. C Sf '*«'

TNDEX

Absorption coefficient, 13i

tables, 137.
Acetylene, 200.
Acidity, 140, 142, 143.
A. ids, 144, 157, 212, 213, 216, 217.
Adaptation, 5, 36, 66, loll. 274.
Adsorption, 128, 129, 130.
Air, 135.

tables, 135.
Alcohols, 212.
Algol, 46, 47.

Alkalinity, 142, 143, 155, 167-170,
188.

blood, 155-159.

sea water, 167-170.

table, 169.
Ammonia, 66, 110, 263, 264.
Analysis of evidence, 250-253.
Animism, 284.
Astronomy, 38-49.
Asymmetric carbon atom, 223.
Atlantic, 167, 168.
Atmosphere, 55-60, 134, 135.

tables, 135.
Atomic volume, 10, 11.

curve, 11.
Atomic weights, 14.
Avogadro's Hypothesis, 177.

Balanced solutions, 175.
Baltic, 168.

Bicarbonates in blood, 157.
Biocentric point of view, 110,

312.
Biological chemistry, 19 ;
Black Sea, 168, 169.
Blood, 115, 116, 153, 155-15S,
161.
alkalinity, 155-158, 187.
serum, 116.

tables, 116, 187.
Boron, 265.

Bosphorue, 168.
Bottom water, l(
Boyle'i Law, 177.
Bromine, 209.

Calcium oarbonate, 172, 173.

Caloric, 81.

Cane sugar, l

Capillary action, 78, 126, I

Carbohydrates, 218,

complexity of reaction

instability, 223-221

mutarotation, 21

photosynthesis, 227
Carbon, 55, 56, 64, 211. 246.

constituent of environment, I

in stars, 55, ">(">.
source of energy, 2 16.
unique chemical properties, 21 1 .
Carbon chains, 210.
Carbon oompoun 194,

246.
Carbon dioxide, Chapter IV
(133-163), 56, 61,
64, 65, 61
absorption coefficient, 136-140.
acidity, 140 168.
atmospheric, 184, 186.
distribution, 138, I
ration, 189, 140,

in sea witter. 1 70.

metabolism, 182, 188.

necessary cmnpom itmos-

phen
r. gul it* - neutrality, 1 17,
solubility, 186 I M)

Carl ><>nie acid iioridr.

< '- lestial i 163.

( Sbaracteristiol of lif
Inoompleteness <>f.

( 'hernieal propert

20-.' -:.

313

314

INDEX

Chemistry, Chapter VI (191-248).

inorganic, 237-243.

organic, 191-237.
Chlorine, 209, 242.
Chlorophyll, 230, 240, 241.
Circulation of water, 91, 180-182.
Classification of organic com-
pounds, 212.
Climate, 87.

table, 87.
Coagulation, 90.
Coal, 57.

Colloids, 77, 123, 128, 129, 130.
Color, 263.
Combustion, 25.
Complexity, 31.
Compounds of carbon, hydrogen,

and oxygen, 202-207.
Compressibility, 262.
Concentration, 171.
Conditions, 31, 164-180.
Conservation of energy, 15, 18,

25, 286.
Constitutional formulas, 197-207.
Contraction, see Expansion.
Copper, 241.

Cosmic evolution, 131, 301-312.
Cosmography, 39, 60, 61.
Cycle of matter, 26-28.
Cyclic compounds, 200, 201, 219.

Degradation of energy, 18.

Design, 85, 307.

Dew, 105.

Diabetic coma, 157.

Dielectric constant, 121, 122, 125.

table, 125.
Digestion, 232.
Distribution, 128, 138.
Double bonds, 200.
Dulong and Petit's Law, 82, 83, 84.
Durability, 31.
Dynamics, 2, 16.

Earth, 61-63.
Electricity, 256.
Electro-physiology, 124.
Elements, 72, 73.
chemical, 9-15.

figure, 11.

table, 14.

Energy, 15-19, 68, 69, 237.
Entelechy, 293, 300.
Environment, Chapter II (38-
71), 8-21, 32, 33, 183-190.
possible, 49-51.

primary constituents of, 61-63.
Enzymes, 90, 230, 231.
Ethane, 198.
Ethylene, 200.

Evaporation, 92, 97, 98, 101, 102,
103, 127, 174, 180.
latent heat of, 97-103.
table, 99, 100.
Evolution, 278, 279.
Excretion, 139.
Exhaustiveness of treatment, 253-

267.
Expansion, 106-110.
table, 107.

Fauna, 186.

Figure, the atomic volume curve,

11.
Final causes, 4, 276.
Fitness, Chapter I (1-37), 4-8,
65, 66, 69, 131, 132, 266,
267, 274-282, 305-307.
explained by Darwin, 5.
Flora, 186.
Form, 24, 26, 32.
Formaldehyde, 225, 228, 229.
Freezing point, 93, 94, 178, 179.
depression, 178, 179.

tables, 178, 179.
table, 94.
Frog's muscle, 262.
Fusion, 92-94.

latent heat, 92-97.
table, 95, 96.

Gastric juice, 242.
Gay-Lussac's Law, 177.
Geology, 73, 112, 173.
Geophysics, 52-55.
Germanium, 12, 13.

table, 13.
Glucose, 160, 222-227.

formation, 227.

mutarotation, 223.

reactions, 224-226.
Glycerophosphoric acid, 241, 242.

INDIA

9 1 5

Glycogen, 234.
Gulf Stream, 1*83.

Hsamocyanine, 241.

Haemoglobin, 'J 1 1 .
Heat of combustion, 80, 217,
246.

table, 246.
Hoat of formation, 244 247.

tables, 244, 247.
Hoat of reaction, 235, 236, 243
247.

table, 236.
Helium, 41, 42, 58.
Henry's Law, 137.
Herring, 175.
Heterogeneous equilibrium, 151,

158.
Hexakontanr. 210.
Hoxanos, 198, 199.
Hippuric acid, 234.
Histidine, 226.

Homogeneous equilibrium, 149.
Hydrocarbons, 197-202.
Hydrogen, 55, 56, 58, 64, 211,
237-243, 245.

ions, 141-143, 169.

in sea water, table, 169.
Hydrogen sulphide, 152.
Hydrolysis, 159, 232-237.
Hydroxyl ions, 141-143.

Impetus, 281, 293-295.
Inactivity, 147.
Inorganic chemistry, 287—243.
Instability, 221.
Interstellar Bpace, 60.
Iodine, 209, 242.
Ionization, 118 126, 155.

constant, 140-163, 216.
tables, 144, 216.

water, 141-143.
Iron, 241.

Lactic acid, 2l'">
Latent neat, 92 106, 12

tables, 95. 96, 99, 100.
Lesina, 166.

table, 16
Levulose, 22 I -26.
Life, origin of, 288, 309, 310.

bic1

Liu . 1*6.

I rj dc Bruyn'a phenomenon.
224.

ium, 24 1 .

Mam, - i .,f, li.v

M <.-- Law, 16

Mlltter, 8 15.
Me. ha,

Mechanism, 2£ 01.

Mediterranean, i • . }, 174.
Melting m.

Melting point, m I ■ ■ wimQ point.
Metabolism, 24-2J
168.
urology, 57, 5S :
Mi th.-.r,,-, L97.

Methyl formate,
Methyl glyoxal, .
Methyl imidasol, 226.
Mobility, 139, 184.
Mobilisation, 1 15, 141.
Molecular constitution, 28, 196-

210.

Molecular volume, 125.
Morphology, -
Mutarotataon,
Mutation, -

iral selection, l, 166

2 si
iral the.,1,
v bubs, 4

Niptuiii-m. 73.

'it;.. 1 12, 1 I! 1 If

ilataon, l '<

■
Nitrogen, 211.

impounds of, . 19.

North Sea, 168, 169.
Nucleic acids, 241 .

m, Chapter V • » 190). 18
li.;. 114,

l.v

alkalinity. 167 171.

table, I-

as environment, lv'%-190.

316

INDEX

Ocean, concentration, 171-176.
table, 171.
currents, 88, 180-182.
mobility, 180-182.
osmotic pressure, 176-179.

tables, 178, 179.
regulation of conditions, 164-

180.
temperature, 165-167.
tables, 165, 166, 167.
Oceanography, 165.
(Edema, 161.
Optical activity, 223.
Order, 1.
Organic chemistry, 28-30, 191-

237.
Organism, 21-36, 63, 76.
Osmotic pressure, 176-180.
Oxidation, 25, 246, 247.
Oxygen, 64, 211, 237-243.

Paleocrystic ice, 108.
Panspermia, 50.

Paraffine hydrocarbons, 212, 214.
Partial pressure, 137.
Periodic system, 9, 11, 14, 210,
211, 303, 304.

figure, 11.

table, 14.
Pharmacological action, 175.
Phase Rule, 257-261.
Phosphoric acid, 146, 147, 156.
Phosphorus, 241, 242.
Photosynthesis, 27, 227-231.
Physical chemistry, 256, 257.
Physiology, 22, 123, 124.
Planets, 46, 60.
Possible environments, 49-51.
Primary constituents of the en-
vironment, 61-63.
Propane, derivatives of, 203-205.
Properties of matter, 70.

interconnection, 276, 277.

omitted, 261, 262.
Proteins, 156, 242.
Protoplasm, 26, 129, 130, 153,

155, 156.
Purpose, 1, 307.

Radicals, 211-218.
Rain, 105.

Red Sea, 174.

Reduction, 227, 228, 231, 244,

247.
Reflex action, 284.
Regeneration, 290-292.
Regulation, 31, 164-180, 186, 189.
Repair, 290-292.
Respiratory center, 157.
Rivers, 113, 172, 180.
composition, 113.
table, 113.

Salinity, 113, 114, 171-175, 187.

table, 171.
Salt, 113, 114, 172, 173.
Sea urchin, 175.
Sea water, 114, 153, 154, 155, 185.

a balanced solution, 175.
Silicon, 66, 265.
Skager-Rack, 168.
Soil, 78, 127.
Solar system, 60, 61.
Solidification, 108.
Solubility, 136-138, 140.

of carbonic acid, 136-140.
Solvent, 68, 79, 111-118, 121.
Sound, 256.
Space, 19-21.

Specific heat, 67, 68, 80-91.
Stability, 78, 150, 164, 186, 218.
Stars, 41-44, 50.
Sugars, 218, 222-232.
Sulphur, 209, 242.
Sulphureted hydrogen, 152.
Sulphurous acid, 169.
Summary, 267-273.
Sun, 44-46, 50, 60.
Surface temperature, 166.
Surface tension, 126-130.
Survival of fittest, 288.
Synthesis, 192, 286.

Tables:

Absorption coefficients, 137.
Alkalinity and acidity, 148,

150.
Alkalinity of sea water, 169.
Comparison of blood and sea

water, 187.
Comparison of properties, 125.
Composition of air, 135.

INDEX

317

Composition of blood strum,

116.
Composition of river water,

113.
Composition of sea water, 171.
Derivatives of propane, 203-

205.
Elements, 14.
Expansion of water, 107.
Fitness, 250-252.
Freezing point of blood serum,

178, 179.
Germanium, 13.
Heat conductivity, 100.
Heat loss of dog, 103.
Heats of combustion, 245.
Heats of formation, 247.
Heats of reaction, 236.
Heats of reduction, 244.
Ionization constants, 144, 216.
Latent heat of fusion, 95, 96.
Latent heat of vaporization,

99, 100.
Melting points, 94.
Normal temperatures, 87.
Properties omitted, 261, 282.
Range of temperature, 165, 166,

167.
Specific heats, 81, 83.
Surface tension, 126.
Vapor tension, 105.
Teleology, 279-282, 289, 298-300,

301, 305-312.
Temperature, 67, 137, 153, 165,
166, 167. 170, 188.
range, 165, 166, 167.

tables, 165, 166, 167.
tables, 87, 165, 166, 167.
Temperature regulation, 70, 86,
87, 89, 91, 95,98, 102, 108,
109, 167.
Theory of solution, 177, 179.
Thermal conductivity, 106, 125.

table, 106.
Thermal properties, 80-110.

Th.-rmorhpniistrv

Therniodynamics, 16, 18, vj, ;

Tim.-, 10 21.

:<■ winds, 181.

Treble bonk, 200.

Orea, 102, 284.
Urine, 117.

Valence, 100, 197.

Y:ui (l.-r Waals's <•<»!

Vaporization,

Vapor t.-ii.-ioii, 104, !

table, 106.
Variable stars, 40, 47.
Variety, 08, 207, 220.
Velocity of reaction, 90, 94, 159,

170, 171.
Vital force, 101, 2E
Vitalism, 282-800, 806.

of Bi-rgaon. - «.

Volcanoes, 56, 134.

Water, Chapter III (72-182), 57,
61-67, 131 ; transpan d
100; as element, 72, :

universal important

78; Quantity and distri-
bution, ~ ohettiosl
inertness, 7'.' ; thermal pi

erties, SO 1 10 ;

beat, sl> 01 t upon

tnnperaturr, s»i \>\ : Lit<nt
heat, 02* 106 ora-

tion, 101 104 : •'II-

sion. 104, 106; then
conductivity, 100; i cpea-
:i, 100 li": ■ohrant,

111 118; ionization. 118-

8 ; surface I
180; in soil. 120, 127;

fitness, 181.
vapor. 101.
Weathering. 114, 140.

Winds, B8, I8L

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North Carolina State University Libraries

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FITNESS OF THE ENVIRONMENT AN INQUIRY INTO TH

S02776483 M