~B\o\
C.

Conklin, Edwin Grant
Problems of Organic Adaptation.

[Rice Institute Pamphlet.
Vol.8. No. 4.]

THE

RICE INSTITUTE
PAMPHLET

VIIJ October, 1921 No/4

Published by

THE RICE INSTITUTE

A university of liberal and technical learning
founded by WilliamMarshRiceintheCity of
Houston, Texas, and dedicated by him to
I the advancement of Letters,Science,andArt.

C.

THE

RICE INSTITUTE
PAMPHLET

Vol. VIII October, 1921

No. 4

Published by

THE RICE INSTITUTE

M

A university of liberal and technical learning
founded by William Marsh Rice in the City of
Houston, Texas, and dedicated by him to
the advancement of Letters, Science, and Art

THE RICE INSTITUTE PAMPHLET
VOL. VIII OCTOBER, 1921 No. 4

CONTENTS

PACK

PROBLEMS OF ORGANIC ADAPTATION — A course of
three lectures delivered at the Rice Institute, March
8, 9, and 10, 1921, by EDWIN GRANT CONKLIN,
Ph.D. (Johns Hopkins), Professor of Biology in
Princeton University.

I. Fitness in the Living World 299

II. The Mechanism of Adaptation 328

III. Mechanism, Vitalism, and Teleology 351

PROBLEMS OF
ORGANIC ADAPTATION1

LECTURE I
FITNESS IN THE LIVING WORLD

A DAPTABILITY may be defined as the power of self-
<L\. regulation, self-preservation, and race perpetuation, by
means of which living things are enabled not only to remain
alive but also to adjust themselves to varied environmental
conditions and to leave offspring. From the standpoint of
any species the best that can happen is to increase and multi-
ply, the worst is to become extinct. Self-preservation and
race perpetuation are the summum bonum; everything that
makes for these is beneficial and adaptive, everything that
prevents or hinders these is injurious or unfit. Adaptability
is a fundamental property of living things without which life
itself could not long persist, for as Herbert Spencer has said,
life is "continuous adjustment of internal relations to ex-
ternal relations." The origin of this or of any other funda-
mental property of life, such as metabolism, reproduction,
or irritability, is shrouded in the same mystery as the origin
of life itself.

On the other hand, adaptations are special adjustments
to particular conditions; they are indvidual examples of the
general property of adaptability. As such they have arisen
in the course of organic evolution, and their origin, no less
than other special structures and functions, must be ex-
plained by any adequate theory of evolution.

XA course of three public lectures delivered at the Rice Institute, March
8, 9, and 10, 1921, by Edwin Grant Conklin, Ph.D. (Johns Hopkins), Profes-
sor of Biology in Princeton University.

300 Problems of Organic Adaptation

Such special adaptations to particular conditions of life
are very common among all organisms, but they are not
universal. Some organisms have been able to adjust them-
selves to one kind of environment and others to another
kind, and although a certain degree of adaptability is uni-
versally present, no single organism is able to adjust itself
to every kind of environment. Special adaptations to par-
ticular conditions of life are examples of differentiation,
which always implies limitations in certain directions in
order to progress in other directions. Consequently one
organism is peculiarly fitted for one environment and
another for another, but no organism is universally fitted
for all environments.

Again, adaptations are relative but not absolute adjust-
ments. Even the most perfect adaptation is not absolutely
perfect. For example, that marvel of adaptation, the human
eye, is very far from being a perfect optical instrument;
Helmholtz is reported to have said that if an optician
should send him an optical instrument as imperfect as the
human eye, he would send it back to him and tell him to
learn his business; and yet there is probably no more perfect
adaptation in nature than this. Furthermore, all grada-
tions of adjustment occur among different organisms from
the relatively imperfect to the most perfect, and these
gradations indicate that fitness in the living world is rela-
tive and not absolute, and they indicate that adaptations
are a product of natural evolution rather than of super-
natural creation.

Adaptations to particular conditions of life are seen in
almost every structure, function, and relation of organisms ;
in the microscopic and ultra-microscopic parts of cells, as
well as in entire cells, tissues, organs, systems, biological
persons, and animal states; in the chemical and physical

Fitness in the Living World 3 ° l

constitution and behavior of protoplasm and cells as well
as in the morphological and physiological modifications
which fit the organism to changed conditions of environ-

r

ment.

So general are such adaptations that it has often been
asserted by naturalists and philosophers that they are uni-
versal— that all structures, functions, and relations of living
things are adaptive or useful, or at least that they were
adaptive at the time of their origin, and that, with regard
to every vital process, we may properly ask the question,
cui bono, being confident that it is or has been useful. This
postulate of universal utility in the living world could be
maintained only by assuming that many things which are
now injurious had once been useful, and that many things
which now seem to be useless will sometime be found to
have a use. Such a postulate may be logically and hypo-
thetically possible, but it is very improbable. While there
are innumerable instances of utility in the living world,
there are thousands of cases where structures, functions, or
relations are in all probabilities not useful but indifferent,
and some cases, though relatively few, in which they are
positively injurious. Therefore it is not possible to maintain
the postulate of universal utility in the living world.

Having found that general adaptability is universal in,
the living world but that success in making adaptations to
particular conditions is never perfect and is sometimes
lacking altogether, and that it is not safe to assume that
every structure, function, or relation of organisms confers
some known or unknown benefit upon its possessor, we may
proceed to examine in detail some of the more striking and
wonderful fitnesses which are found in the living world.

In this survey, we shall deal not only with the general
relations of organisms to their environments but also with

3 o 2 Problems of Organic Adaptation

the intimate and minute adaptations found in organs, tissues,
and cells, and we shall consider first, inherited adaptations,
and later, acquired ones.

Our object is not to catalogue and describe the multi-
tudes of adaptations which have been observed among
animals and plants, but rather to find an explanation of their
origin. However, since some recent writers have adopted
the method of explaining adaptations by explaining them
away and have solved the problem of their origin by deny-
ing their existence, it seems advisable to review some of the
more striking fitnesses that are found among living things
and especially among animals.

Let us begin by freely admitting that under the influence
of the doctrine of supernatural design there has been a
marked tendency to exaggerate the frequency and the per-
fection of organic adaptations. Many naturalists have seen
adaptations where they do not exist and have invented
environmental conditions to fit these fanciful adaptations,
and when the usefulness of any structure or function could
not be made probable even by these means, it was always
possible to assume that this was due merely to our ignorance
of the real functions of the part in question or the real
needs of the organism. Sometimes the purely mechanistic
results of necessary physical, chemical, and biological con-
ditions have been regarded as special adaptations, and in
general, the attitude of those who are looking everywhere
for adaptations has not been very critical.

But when we are assured by some modern critics that all
adaptations can be explained away in this manner, is it not
evident that extravagant and uncritical opinion has swung
to the other extreme? Adaptations may not be universal,
they may not be perfect, but that they are very numerous
and frequently so delicately adjusted to needs as to excite

Fitness in the Living World 3°3

the admiration of the thoughtful, let the following classi-
fication and illustrative examples testify:

I. RACIAL OR INHERITED ADAPTATIONS

Inherited adaptations are those which appear in the
development of individuals as if in anticipation of future
needs and not as a result of present ones. The eye, for
example, usually develops in the entire absence of light, and
its various parts are formed as if in anticipation of their
future uses; the same may be said of almost every other
inherited adaptation. Particular adaptations characterize
certain races, species and larger groups of organisms.
Among these are innumerable structures, functions, habits,
and instincts; indeed, one can think of scarcely any normal
structure or function, reflex or instinct, that does not illus-
trate such racial or inherited adaptation.

1. The Efficiency of the Living Machine

This is an age of machinery, and the fitness of any
machine is measured by its efficiency. Let us consider the
fitness of the living machine as contrasted with those of
human invention.

The frame or skeleton of most vertebrates is so con-
structed as to give the maximum of strength with the mini-
mum of weight. Long ages before men had thought of
using tubular frames in machines such as bicycles, nature
had been using them in the shafts of long bones; ages before
wire wheels and tangential spokes were thought of spicules
and trabeculae of bone were laced through the ends of long
bones so as to afford maximum strength with minimum
weight. Long before any human being had discovered, used,
or classified the different forms of levers, nature had been
using them in the limbs of arthropods and vertebrates.

304 Problems of Organic Adaptation

The mechanical principles of the wheel and the screw are
not found anywhere among organisms for the obvious
reason that every portion of the animal machine must be
connected by blood vessels and nerves with the central part,
but the use by animals of levers of all kinds and for every
conceivable purpose has never been surpassed in machines
of human invention.

The motive power of the living machine is found in pro-
toplasmic contractility whether it manifests itself in amoe-
boid, ciliary, or muscular movement. But since all movement
of large bodies must be brought about by muscles, we may
limit our consideration to this type of movement. In spite
of the fact that more attention has probably been devoted
to the structure and function of muscle than to any other
animal tissue, the ultimate causes of muscular contraction
are still problematical. Nothing comparable to this form
of motion exists except among animals. It is known that
the chief source of chemical energy in muscular contrac-
tility is the burning of dextrose, but the manner in which this
chemical energy is transformed into mechanical energy is
unknown. However, the relative efficiency of different types
of engines is known, and they may fairly well be compared
with the living engine. The ordinary steam engine trans-
forms about 10% of the energy of the steam into motion;
the steam turbine, about 17%; the Diessel internal combus-
tion engine has a practical efficiency of about 30%, while
muscle has a net efficiency of from 20% to 30%. The living
engine is therefore more efficient than the steam engine and
about as efficient as the best type of engine that has been de-
vised by man. But in addition to this, the temperature
developed in muscle is much less, and the flexibility of the liv-
ing machine, as measured by the rate or extent of movement,
is much greater than in any other engine. For example, the

Fitness in the Living World 3°5

temperature never exceeds 110° F. and is usually much less
than this, while it reaches 5000° F. in a gas engine; the rate
of contraction may vary from movements so slow as to be

r w

scarcely visible to a rapidity of about 24,000 contractions
a minute, as in the beating of a mosquito's wings ; the extent
of movement may vary from a scarcely perceptible shorten-
ing to one one-hundredth part or less of the maximum ex-
pansion, as for example, in certain worms and in the tenta-
cles of some coelenterates.

Consider the variety, complexity, and efficiency of the
means of locomotion in animals. Among the marvels of
nature Solomon enumerates "The way of the serpent on the
rock and the way of the eagle in the air," but the more
usual forms of locomotion, such as running, jumping, climb-
ing, digging, sailing, wading, and swimming show fitness
and efficiency that are equally marvelous. Consider the
manner in which unusual speed has been attained in the
horse, giraffe, and antelope by the lengthening of legs and
digits, the elevation of the animal upon the ends of the
middle digits and the loss of the lateral ones. Consider the
remarkable contrivances of the kangaroo, the jack-rabbit,
the grasshopper, the flying squirrel for leaping; of the sloth,
squirrel, and woodpecker for climbing; of the earthworm,
mole cricket, and mole for burrowing. Among aquatic
animals almost every means of propulsion which man has
devised was discovered ages before by lower animals: the
Portuguese man-of-war and the paper nautilus spread their
purple sails to the breeze and "sail the uncharted main" ;
the jelly-fish and squid use hydraulic motors; fish, seals,
and whales employ oars and sculls. Finally, consider the
wonderful adaptations by means of which animals travel
the highways of the air: the spider which spins a thread
that floats out on the breeze and then, clinging to this gos-

306 Problems of Organic Adaptation

samer, goes "ballooning" to new lands; the tremendous
power of flight of the albatross and eagle; the apparently
effortless soaring of the buzzard and frigate-bird; the flight
of the arctic tern and golden plover from pole to pole, or
the world-wide flight of the tiny humming-bird. Long ages
before man had appeared on the earth, animals had con-
quered the land, the water, and the air; and although by
means of his machines man can now surpass them in speed
and strength in these three elements, they can still teach
us much in skill and efficiency of locomotion.

The heart, with its valves, is a remarkably efficient
pump; the strength and thickness of the muscular walls of
the auricles and ventricles are nicely adjusted to the "load" ;
the valves are ideally constructed for quick, simple, and
efficient action; the sequence of the beats in auricles and
ventricles is usually perfect. Even more remarkable are
adaptations to increased "load" during violent exercise or
in high altitudes. In man the resting heart pumps about
five pints of blood a minute, but in violent exercise it pumps
seven times as much as this. The structures of arteries,
veins, and capillaries are admirably suited to the needs of
efficient circulation, and the mechanism for regulating blood
pressure is extraordinarily efficient.

The efficiency of the living machine in the production of
light, as for example in the firefly and glowworm, is incom-
parably greater than in the case of any lighting system of
human invention. In electric lighting from 90 to 95% of the
energy is wasted in heat and only 5 to 10% produces light,
whereas these proportions are reversed in living things.

The mechanism for heat regulation in warm-blooded
animals is wonderfully perfect. Irrespective of extreme
changes in external temperature, the internal temperature
is frequently maintained for years at a time within a few

Fitness in the Living World 3°7

tenths of a degree. Anyone who has ever tried to maintain
an incubator at constant temperature, and especially under
greaJ external changes, will be in a position to appreciate
the remarkable efficiency of this living thermostat. In hiber-
nating animals the body temperature falls during the winter
sleep, and in severe weather it may continue to fall until it
approaches the freezing point. The animal then wakes up,
as if an automatic alarm had been set to rouse it when the
danger point had been reached, and by means of muscular
movements, increased respiration and oxidation, and some-
times by feeding, the temperature is raised. This safety
device is found not merely in the highest warm-blooded
animals, such as hibernating bears, but also among some
insects, such as bees. When the temperature in the winter
cluster of bees goes below 57° F. the bees become active,
eat honey, oxidation increases and the temperature of the
cluster rises.

The respiratory mechanisms by which oxygen is brought
into contact with every particle of living substance and the
exhaust gas is eliminated are far more perfect than is to be
found in any other engine. In the case of insects, minute air
tubes or tracheae run to every part of the body, whereas in
many other animals in which respiratory organs (gills or
lungs) are limited to certain regions, the blood contains a
substance, haemoglobin, which serves as a wonderfully effi-
cient oxygen carrier.

The mechanisms of living things for obtaining, preparing,
absorbing, and utilizing substances as fuel are incomparably
more complex and efficient than in any engine of human
devising, and the utilization of foods for growth and repair
is wholly unparalleled in any other mechanism.

The uniqueness of the living machine is nowhere more
evident than in its capacity for reproduction. Imagine any

308 Problems of Organic Adaptation

machine of human invention which had the power not only
to do the work for which it was devised but also to give
rise indefinitely to other machines of the same sort I Noth-
ing could illustrate more clearly the fundamental difference
between the living and the lifeless machine than this power
of reproduction. If reproduction is one of the fundamental
and original properties of living things and is therefore
not to be explained as a result of organic evolution, at least
the innumerable adaptations for promoting reproduction
have arisen in the course of evolution and demand an ex-
planation. Among these are the differentiations of male
and female sex cells and all the differences in structure,
functions, and instincts between males and females; the
remarkable contrivances for insuring cross fertilization in
plants and animals and for preventing hybridization of
species; the infinite variety and nicety of the means for the
protection and nourishment of the young. Nothing in the
whole world of living things is more wonderful than these
adaptations for reproduction.

Consider the wonderful fitness of the nervous system for
receiving and transmitting stimuli and for coordinating the
multitudinous activities of animals. The timer of an auto-
mobile is no more perfect than the timing of the various
contractions in the heart beat, and the timing of various
muscular contractions in standing or walking and much
more in talking or in playing any game such as tennis
or baseball is vastly more complex and perfect than in any
lifeless machine. Think of the fitness of every organ for
its particular use and then consider the peculiar fitness with
which these organs are coordinated into an harmonious
whole.

Think of the variety and range of sensations in any higher
animal and the admirable fitness of the sense organs: the

Fitness in the Living World 309

fitness of the organs of touch and taste and smell, and the
complex fitnesses and coadaptations of the many parts of the
ear and eye. Many instruments of human invention are
more sensitive to particular kinds of stimuli than some of the
sense organs. For example, a thermometer is more sensitive
to temperature changes than our heat and cold organs, the
photographic plate is more sensitive to light than the retina,
the microphone more sensitive to vibration than the ear;
but when one considers the range and variety of stimuli to
which higher animals are sensitive, there is no doubt that
their sense organs are much more efficient than any non-
living mechanism.

Finally, consider the durability of the living organism and
its power of self-regulation and self-repair as compared with
any other machine. Not for one moment between birth and
death does the living engine stop. The heart and respira-
tory muscles cannot rest for a minute at a time during the
whole course of life. Engines have been built that would run
for a month or two without stopping for repairs, but the
heart may continue to beat without interruption every second
for a hundred years, pumping during this time not less than
sixty million gallons of blood. The regulatory power of an
organism is incomparably more varied and perfect than in
any other mechanism; not only do all the complex processes
of life occur, under normal conditions, in the best possible
sequence and to the most favorable extent, but when as the
result of abnormal conditions these processes are disturbed,
the living machine has a wholly unparalleled capacity of
regulation and restoration. When the living machine under-
goes wear, injury, or loses parts, it is able to a surprising ex-
tent to repair itself and to restore or compensate for lost
parts. What other kind of machine has a regulatory power
that is comparable with that of a living thing?

3 i o Problems of Organic Adaptation

When we consider the wonderful efficiency of the living
machine in all of the respects named, is it any wonder that
there have always been those who have refused to believe
that it is really or only a machine? Is it any wonder that
they have insisted that it must be controlled by some sort
of indwelling intelligence? When we consider these remark-
able characteristics, we may well say in wonder and admira-
tion, "What a piece of work is a man!" or any other
organism.

Such adaptations to general conditions of existence are
so common that to most persons they do not seem remark-
able, while some peculiar adaptation, such as the leaf-insect
or the Venus fly-trap, seems wonderful simply because it
is not common. Many of these more uncommon adaptations
have played an important part in the discussion of the vari-
ous theories of evolution which have been advanced during
the past century. As illustrations of adaptations to peculiar
conditions of life may be mentioned the fitness of horses'
limbs for running, those of seals for swimming, those of
birds for flight; or the adaptation of the long neck and fore
legs of the giraffe to its habit of browsing on trees; of the
long necks and legs of wading birds to their peculiar habits;
of the small fore legs and large hind legs and tail of the
kangaroo to its peculiar method of locomotion. In this con-
nection must also be considered the absence of limbs in
certain lizards, snakes, and amphibians, and the degenera-
tion or loss of wings in the apteryx and dinornis among birds
and in certain insects inhabiting stormy islands. Here also
must be classed the cases of adaptive atrophy or hyper-
trophy of organs, as for example the loss of eyes by cave
animals, the decreased size of the jaws and teeth of civi-
lized man as compared with savages, the increased size
and length of the middle digit, and the reduction or dis-
appearance of the lateral digits in ungulates, etc.

Fitness in the Living World 3 1 I

2. Adaptations for Defense and Offense
Every principle of defense known and used by man has
been employed by lower animals for uncounted millions of
years. Among these are thorns, spines, ancf armor, camou-
flage, the false flag, and that most effective means of defense
— a strong offense. Thorns and spines, frequently barbed
and poisonous, are of wide occurrence among animals and
plants. The cactus and bramble, the sea-urchin and porcu-
pine, ward off enemies by their bristling surfaces. Mollusks,
Crustacea, armored fishes, dinosaurs, tortoises and arma-
dillos are veritable armored cruisers or land tanks.

Nowhere has the principle of camouflage been carried to
such extent or perfection as among certain animals. The
principle of protective coloration is of very general occur-
rence in the animal world. The polar bear and fox, the lion
and antelope, the dark upper and light under surfaces of
birds, resemble the backgrounds against which they are usu-
ally seen. Even the tiger and zebra are protectively colored
to match the lights and shades of their natural habitats, a
thing which can be readily believed by anyone who has seen
the bizarre bars and patterns on camouflaged ships. When
the background changes, as from winter to summer, some
animals change their colors, as in the case of the ptarmigan
and arctic hare, which are white in winter and gray or brown
in summer. Other animals change colors and patterns very
rapidly to match corresponding changes of the background,
as in the case of cephalopods and fishes (especially floun-
ders), amphibians and reptiles (notably chameleons).

Animal camouflage includes not only colors and color
patterns, like those of the background against which the
animal is seen, but also shapes and outlines like those of sur-
rounding objects. Some fishes, crustaceans, mollusks, and
worms which live in sea-weed are covered with streamers,

312 Problems of Organic Adaptation

and ragged processes so like sea-weed that it is very difficult
to distinguish them from the weed. Certain animals, such as
the stick insect, dead-leaf butterfly, and bark spider are so
much like the objects on which they are commonly found,
both in form and color, that it is difficult to detect them
even when searching for them. Other common forms of
camouflage are found in "feigning death," or rather in re-
maining perfectly quiet to escape detection, for moving ob-
jects even though they have concealing colors or forms are
much more readily seen than those that remain motionless.

The use of a "false flag," which has been so much con-
demned in human warfare, has apparently been resorted to
by animals in certain instances. Such sailing under false
colors is known in zoology as "mimicry." Insects that are
protected by nauseous odors or by other means are some-
times mimicked in form, color, and peculiarities of posture
or locomotion by other insects not closely allied to them.
Snakes that are non-poisonous sometimes mimic poison-
ous ones in forms, colors and threatening attitudes. But in
zoology it is almost as difficult to establish the use of a false
flag as it is in naval warfare, and it may be that two different
species have independently developed similar flags so that
neither is "mimic" or "mimicked."

Electrical fishes, such as the electric eel and the torpedo,
are able to generate a strong charge of electricity with which
they can shock and stun their enemies or their prey. Of
course submarines and flying machines are an old story in
animal life, and even smoke screens, or what correspond to
these, are used by the squid and other cephalopods which in
fleeing from enemies throw out a cloud of ink which conceals
them. These modern methods of human warfare have been
used for millions and even hundreds of millions of years by
lower animals.

Fitness in the Living World 313

In animal, as well as in human warfare, the most effective
defense is a strong offense, and innumerable adaptations are
found for this purpose. Among these are many ferocious
modifications of teeth, such as tusks, sabers, and swords;
great developments of spurs, claws, pincers, and horns;
poisons and poison gases, such as the sting of the bee, the
poison of serpents and scorpions, the odors of bugs and
skunks. These last anticipate in many respects some of the
newest methods of gas warfare. But although many animals
have stings and spears, none has developed projectiles that
can be discharged at a distant mark.

When one considers all these striking contrivances for
defense and offense, together with the appropriate behavior
by which they are accompanied, such as the well-known
habits of the rattlesnake, the porcupine, the opossum and
the skunk, the question inevitably arises whether lower
organisms have not discovered these means of protection
in a manner comparable to the way in which man has dis-
covered methods of defense and offense.

3. Interorganismal Relations

Another class of racial adaptations is found in certain
typical correlations between animals and plants, between
different species of animals or plants, and between different
individuals of the same species. Fifty-six years before
Charles Darwin published the "Origin of Species," Konrad
Sprengel (1793) published a work entitled "Das neue ent-
deckte Geheimniss der Natur" in which he proved that
flowers exist for the purpose of attracting insects in order
that the insects may carry pollen from flower to flower, thus
insuring cross fertilization. The contrivances by which
flowers attract insects, such as color, scent, and nectaries,
reach a climax in such plants as orchids, in which the nectary

3 ! 4 Problems of Organic Adaptation

can be reached only by a particular route and by certain spe-
cies of insects, and the pollen is so located in the flower that
masses of it will become attached to the proboscis or other
portions of the insect, and these masses will then be depos-
ited upon other flowers of this species visited by the insect.
Both flowers and insects are benefited by this adaptive rela-
tionship. The yucca moth collects pollen from one flower of
the yucca, flies to another flower and lays her eggs among the
ovules, and then places pollen upon the stigma, without
which fertilizing act the ovules would not develop. As the
larvae of the moth develop, they eat a part of the ovules but
leave a part, so that seed is produced, and thus both species
are perpetuated. This act is performed but once in the life
of a moth, so that there is no opportunity of learning by ex-
perience or imitation. It is a principle in such mutual depen-
dence that each member must conserve the other, and even
in parasitism the parasite must not usually destroy the host
else it will at the same time destroy itself.

Extraordinary cases of adaptation are found in the pe-
culiar life histories of certain parasites, which must pass
through one or more larval stages in intermediate hosts
before they reach the adult stage in the final host. Consider,
for example, the almost infernal ingenuity shown in the life
history of the malarial organism, which adapts it to life in
the mosquito and in man and to its transfer from one to the
other; or the adaptations shown in the life history of the
liver-fluke, which passes through four different larval stages
in one or two intermediate hosts before reaching its final
host; or the life histories of the tapeworm or hookworm or
trichina, which are wonderfully adapted to securing the sur-
vival, multiplication, and distribution of these parasites.
Perhaps nothing in nature exceeds in complexity and nicety
of adaptation the life histories of such parasites.

Fitness in the Living World 3 * 5

The more common relationships of individuals of the
same species, as for example between males and females,
parents and offspring, and all the castes with their different
functions among social insects, are notable instances of adap-
tation. What is more wonderful than the great drama of
sex, in which all living things, except the very lowest plants
(bacteria), are actors, in which admirable coadaptations
for bringing about cross fertilization are found, all the way
from the structures and functions of the egg and sperma-
tozoon to the secondary sexual characters and the compli-
cated instincts and behavior of males and females? Consider
the very common adaptations found in the relations of
parents and offspring, the various methods by which the
young are protected and supplied with food, and the com-
plicated behavior which characterizes this relationship in
higher animals.

4. Adaptations of Development

To the embryologist at least, no adaptations are more
striking than those of development. In the normal develop-
ment of an egg or embryo every step leads to what seems
to be a preconceived end. The differentiations of ontogeny
are usually adaptive. The cleavage of the egg subdivides the
egg substance both quantitatively and qualitatively in such
manner as to determine the relative sizes and locations of
future parts. Even the distribution of substances in the un-
segmented egg may foreshadow the proportions and locali-
zations of future organs. These organs develop not for
immediate but for future uses and in anticipation of distant
needs. For example, consider the development of the eye;
the retina with its sensory rods and cones, the lens with the
ciliary processes and muscles for focusing, the transparent
cornea and humor — each and every portion of the organ

3*6 Problems of Organic Adaptation

develops toward the end, or shall we say "for the purpose,"
of vision, and yet there is no vision until after all these parts
are formed and connections have been made with the central
nervous system, which does not occur until late in develop-
ment, sometimes, as in the case of the rat, some time after
birth. Organs are sometimes developed which are used
only once in the life of the individual, as, for example, the
egg-tooth on the beak of a bird, which is used only for
breaking its way out of the shell at hatching.

In all of its general features development is teleological,
and contemplating this we may well appreciate the words
of the psalmist, "I am fearfully and wonderfully made."
"In thy book all my members were written which in con-
tinuance were fashioned when as yet there was none of
them."

5. Adaptive Behavior

Some of the most striking of all adaptations are found in
the field of behavior and instincts. Even the simplest plants
and animals avoid injurious regions and substances and find
beneficial ones. For example, some bacteria will aggregate
in certain regions of the spectrum and avoid other regions;
they move away from salt solutions, or from distilled water,
and collect in nutritive substances. Paramecium and many
other protozoa behave toward injurious or beneficial sub-
stances in a similar manner, and especially notable is the way
in which Paramecium avoids extremes of heat and cold and
remains in regions of moderate temperature. The tropisms
of germ-cells, of seeds, seedlings, and embryos, are generally
adaptive. In plants as well as in animals the sperm finds the
egg and is received by it. The root of the seedling grows
down into the soil and the shoot up into the light and air.
Sensitive plants close their leaves when stroked or exposed
to dry air, thus preventing injury or dessication. Insectivo-

Fitness in the Living World 3 * 7

rous plants catch insects by sticky secretions or traps, and
they then infold and digest them. The plant known as
"Venus fly-trap" does not respond, by closing, to a single
stimulus, such as would be produced by accidental contact
with a falling object, but only when the stimulus is repeated
within three minutes, as it would be if that object were an
insect; incidentally, this behavior shows that this plant has
a kind of memory ("organic memory") which lasts for a
period of about three minutes.

The behavior of higher plants and animals is almost
always adaptive, and where it is not so it can usually be
explained as the result of unnatural, or at least unusual,
conditions; thus the tendency of insects to fly into a flame is
the result of positive phototropism, which is beneficial in
a state of nature and injurious only in the artificial condi-
tions created by man. The behavior of insects is sometimes
so remarkably adaptive that it seems to be intelligent and
purposive. Thus the solitary wasp, Sphex, digs a burrow in
the ground and stores it with caterpillars which have been
stung in such a way as to paralyze but not to kill them. On
these caterpillars she lays her eggs, and when the larvae
hatch they find an abundance of fresh meat for food. On
leaving the burrow the mother Sphex carefully conceals it
by closing it with earth; the Peckhams and more recently
several others have observed that she then takes a small
stone in her mandibles and pounds the earth down with it
and then smooths the earth so that all traces of the burrow
are removed. The instincts of ants and bees have long been
studied, but they never lose their charm and interest; the
instincts of the different castes or members of the colony,
and even of the same individual at different stages of its
life, are very unlike, and yet all are adapted to the preserva-
tion and prosperity of the colony.

3 1 8 Problems of Organic Adaptation

The migratory habits of animals are no less wonderful.
At the breeding season myriads of shad and salmon migrate
from the sea far toward the sources of fresh-water streams
where the young may grow up in comparative safety, and
although very few of the adult animals ever get back to the
sea, yet this same instinct for migration possesses every new
generation as it did the old one. The immemorial migra-
tions of certain birds, going north in spring and south in
autumn, are equally wonderful. The value of such an instinct
to the birds is easily understood; but how did it arise, what
series of natural causes can explain such an instinct? These
adaptive instincts are no exceptions but only striking illus-
trations of a universal phenomenon among organisms. How
can such useful and apparently intelligent and purposive
adaptations be explained? Are intelligence and purpose in
man fundamentally different from this adaptive behavior
of animals ? Apparently many gradations exist between
these two, and in the development of the human individual
every intermediate step is found between mere tropisms
at one extreme and intelligence at the other. If tropisms
and instincts are generally adaptive, are not intelligence and
purpose higher and more complicated forms of adaptation?

6. Cellular Adaptations

Adaptations are found not only in gross structures and
functions but also in the most minute, not only in tissues
and cells but also in the smallest parts of cells. For example,
what is there in the whole world more remarkable than the
complex mechanism of nuclear division? We now know that
the material basis of heredity is located in certain portions
of the nucleus, the chromosomes, and, if this material is
to be equally distributed in development to all portions of
the body, each chromosome must be divided with exact

Fitness in the Living World 3 1 9

equality and the halves separated into the two daughter
cells formed at each division. This "purpose" is accom-
plished by the complex mechanism of mitosis, which is al-
most universal in occurrence and has existed at least as long
as many-celled animals and plants have, but which was not
discovered by man until the middle of the nineteenth cen-
tury, and its significance has been appreciated only during
the past forty years.

Since chromosomes are persistent structures their number
would double, and the inheritance material would double,
every time a spermatozoon unites with an egg, were not
some provision made to prevent this. Such provision is
made in a unique form of nuclear division, which takes
place only once in the whole life of an individual — in man
once in billions of billions of divisions. This unique division
is brought about by the union of corresponding or homolo-
gous chromosomes of the father and mother at the time of
the formation of the germ-cells — a process known as synap-
sis — and the subsequent separation of these whole chromo-
somes in mitosis, so that each germ-cell, whether egg or
sperm, contains only half the normal number ; then when egg
and sperm unite in fertilization, the normal number is re-
stored. Upon these processes of synapsis and reduction
of chromosomes and subsequent union of egg and sperm
depend all the phenomena of Mendelian inheritance.

The fact that in most species males and females occur in
equal numbers has always been regarded as a remarkable
adaptation — indeed, the fact that males or females, with
their coadapted structures, functions, and instincts, should
occur at all is a notable adaptation. It is now known that sex
is determined by a certain combination of chromosomes; in
the female there are usually two sex chromosomes (xx), in
the male there is only one (#), or a combination (xy)« In

320 Problems of Organic Adaptation

the process of chromosome reduction at the time of the
formation of the sex cells, each egg receives one x chromo-
some, while one half of the spermatozoa receives one x and
the other half a y chromosome or none. If then an egg is
fertilized by a sperm containing an x, a female is produced,
but if fertilized by a sperm containing a y or no sex chromo-
some, a male is produced; and since these two types of
spermatozoa exist in equal numbers it results by mere chance,
on the theory of probabilities, that males and females are
produced in equal numbers. But there is no evidence that
this remarkable mechanism of sex determination is itself
the result of mere chance, and, however it may have been
caused, it is a wonderful example of adaptation.

The fertilization of an egg is a very complex process, and
yet every step in that process is adaptive. An egg ready for
fertilization gives off substances which activate the sperma-
tozoa, and when by its active movements a sperm conies into
contact with the egg, the latter sends out a process to re-
ceive the sperm. Immediately after this the whole surface of
the egg undergoes some change which usually makes it im-
possible for another sperm to enter. If by any means more
than one sperm nucleus unites with the egg nucleus, the
resulting development is very abnormal. Thus the pro-
vision for preventing multiple fertilization and pathological
development is highly adaptive. Many other cases of intra-
cellular adaptations could be cited, but the ones mentioned
indicate that adaptations are found in the smallest as well
as in the largest parts and functions of organisms — "Natura

7. The Subtle Chemistry of Life

Although chemists no longer hold that there is a great
gulf fixed between organic and inorganic chemistry, and

Fitness in the Living World 3 2 l

although certain organic compounds can now be made arti-
ficially in the laboratory, every living thing performs many
complicated chemical processes which the chemist can neither
duplicate nor understand. In particular the power which
all kinds of protoplasm have of converting food substances
into their own peculiar kinds of protoplasm — the power of
assimilation — is a chemical secret which the mind of man
has not been able to discover, although every cell of his body
knows this secret. The secret of "fixing" free nitrogen was
discovered by some of the simplest bacteria hundreds of
millions of years ago, and their efficiency in this respect is
much greater than man can hope to attain either at Niagara
Falls or Muscle Shoals. The ability of all green plants to
convert water and carbon dioxide into sugar and starch in
the presence of sunlight is a secret of such importance that
if man could duplicate the process cheaply and efficiently
it would forever solve the problem of the food supply. The
chemical processes involved in fermentation and digestion
may be artificially duplicated by man, but only with the aid
of chemical substances known as enzymes, which are made
by even the simplest kinds of protoplasm but which cannot
be artificially produced by man.

Other substances known as chemical messengers, or hor-
mones, which are produced by certain ductless glands and
which circulate in the blood, profoundly influence the
growth, development, and activity of many distant parts of
the body — indeed, many of the most remarkable correla-
tions of growth and form, of function and structure, of dif-
ferentiation and integration, are determined by hormones.
There is good reason to believe that they are the real ma-
terials of heredity, and that they determine race, sex, and
type of personality; but although these hormones may be
produced by chromosomes, cytoplasm, and glands, they can-

322 Problems of Organic Adaptation

not in general be synthesized by human intelligence. Other
chemical substances of unknown composition but of the most
vital importance as accessories to food are known as vita-
mins. They are produced only by certain cells and tissues of
plants and animals, and they have never yet been analyzed
or synthesized.

These are only a few of the many unique and wonderful
chemical secrets which protoplasm has discovered but which
are as yet largely beyond human comprehension. How did
lowly plants and animals ever discover such subtle secrets
of chemistry, which intelligent man is only coming to ap-
preciate and which he cannot yet artificially duplicate?

II. INDIVIDUAL, ACQUIRED, OR CONTINGENT
ADAPTATIONS

As contrasted with such racial or inherited adaptations,
there is a whole class of fitnesses which may be known as
individual, acquired, or contingent. These are adaptations
which arise in response to particular stimuli; they are not
inherited, as the structure of the eye is, for example, which
develops in the dark as well as in the light, and which is
fully formed before it is put to the use for which it is fitted,
but they are acquired in that they arise in each individual
in response to particular external conditions, and they are
contingent in that they may or may not appear, depending
upon whether the appropriate stimulus is present or not.

Among these individual adaptations, or useful responses
to stimuli, may be listed the following classes :

Stimulus Beneficial Response

Increased light Increased pigmentation

Increased friction Increased thickness of epidermis

Increased use Increased size or strength

Unusual foods Appropriate digestive fluids

Fitness in the Living World 3 2 3

Stimulus — Continued Beneficial Response — Continued
Unusual temperatures Acclimatization
Poisons or toxins Toleration or antitoxins

Injury Regulation or regeneration

Strong light, and especially light of short wave lengths
such as ultra-violet, is very injurious to protoplasm, and
when the skin of white persons is exposed to such light the
living cells suffer "sun-burn." But another result of such
exposure is that the skin becomes more deeply pigmented or
"tanned," and this screen of pigment serves to protect the
living cells from the injurious rays.

Moderate friction and pressure on the skin, instead of
wearing it thin, leads to the thickening of the epidermis and
the formation of callosities by which the deeper lying parts
are protected. A similar result follows the application of
various chemicals to the skin. The epidermis of plants that
are exposed to salt-water spray becomes thickened, thus pro-
tecting the protoplasm from the injurious effects of the salt.

It is a truism that in living things alone use strengthens
a part and disuse weakens it. The used muscle grows in
size and strength, and, within certain limits, it fits itself to
the task required of it, while the unused muscle grows small
and weak. A similar thing is true of glands, and even sense
organs or brains may be improved by use.

Unusual kinds of food often lead to adaptive modifica-
tions of the digestive organs. Grain-eating birds have a
tough gizzard with a hard lining, but if they are fed on soft
foods the gizzard becomes soft and flabby. If animals which
live largely on meat are put upon a carbohydrate diet, or vice
versa, the character of the digestive fluids undergoes an
appropriate change.

Remarkable also are the adaptations which many organ-
isms show to extremes of temperature and to dessication. By

324 Problems of Organic Adaptation

gradually increasing the temperature of the water certain
protozoa have been acclimatized to water so hot that other
individuals of the same species that have not been so accli-
matized are instantly killed and cooked when placed in it.
Some animals and plants may undergo complete dessication
and yet come out "as good as new" when they are again
placed in water. There is a small rotifer that is found in
rain gutters and cemetery urns which can be completely dried
so that it contains no trace of water. When it is again
placed in water, it is not only completely restored, but is
found to have renewed its youth.

Even more remarkable are the adaptations that organisms
show to certain poisons, if these poisons are given in graded
doses so that the organism acquires a tolerance for them.
Such tolerance may be acquired to a limited extent to violent
mineral poisons, such as corrosive sublimate, as Davenport
showed in the case of Paramecium. It is also known that
human beings, as well as other organisms, may acquire
tolerance for arsenic and arsenical compounds. One such
compound is "salvarsan," and Ehrlich, its inventor, points
out the importance of giving it in doses large enough to kill
the syphilis organism "mit einem Schlag," since the organ-
ism will acquire a tolerance for the poison if it is given in
smaller doses. But the poisons to which living things most
readily become adapted are those of organic origin, such as
alkaloids. It is well known that "drug fiends" may take
enough morphine or cocain to kill a man, who is unac-
customed to the drug, without any very serious or immedi-
ate injury. Similarly, tolerance is gradually acquired for
tobacco, alcohol and many other poisons. Among the most
striking instances of this is the tolerance to serpent's venom
and to bacterial toxins. If the venom of rattlesnakes or
cobras is injected into guinea-pigs or rabbits in graded doses,

Fitness in the Living World 325

they may be rendered immune to the poison even when given
in lethal quantities. The venom of every poisonous snake
is highly specific, and the antidote for one kind of venom
will hot serve as an antidote for another kind. Furthermore,
it is certain that the ancestors of the guinea-pig, which is a
native of South America, could never have had any experi-
ence with the venom of the cobra, a native of India; and
yet the guinea-pig can form an anti-body against cobra
venom, and for every particular kind of venom its own
peculiar anti-body. One who has had diphtheria has ac-
quired a toleration for the diphtheria toxin, so that he is
thereafter usually immune to that disease. In this way most
persons have acquired immunity to certain common diseases.
It is known that each kind of toxin leads to the formation
of a specific anti-body which serves as an antidote for that
poison. Many of these toxins are complex and highly specific
substances, and yet the living organism, if given sufficient
time, can make a specific antidote for each particular kind
of toxin. What chemist by the use of his intelligence could
do anything approaching what his unconscious cells are able
to do in this respect?

Internal regulation is frequently the result of the action
of certain internal secretions, or hormones: Thus the ability
to "nerve oneself" for a great effort involves many cor-
related adjustments, such as increase of heart beat, of blood
pressure, of respiration, and of muscular energy, and all of
these are caused by setting free into the blood "adrenin,"
which is secreted by the adrenal gland; even the coagula-
bility of the blood is increased by this hormone. The adap-
tive character of all these reactions can be readily appreci-
ated when it is realized that these are just the conditions
needed in fight or flight, and in life and death struggles. It is
probable that many regulations of development are depen-

326 Problems of Organic Adaptation

dent upon a proper sequence and balance of internal secre-
tions. Such a secretion known as "andrase," formed by the
interstitial cells of the testes, leads to the development of the
secondary sexual characters of the male in mammals, while
a corresponding hormone, known as "gynase," is formed by
the ovary and causes the development of the secondary
sexual characters of the female. The great changes which
accompany pregnancy and lactation in mammals are caused
by hormones from the ovary and the foetus. Other internal
regulations affecting many parts of the body and the general
course of development are caused by hormones from the
thyroid gland, the pituitary body and many other organs of
internal secretion.

But although the hormone is the chemical stimulus which
leads to the adaptive reactions in each of these cases, it does
not in the least explain the fact that these reactions are
adaptive. Why should the reactions of so many different
organs to adrenin be of such a nature that they cooperate
to fit the animal for fight or flight? Why should the reac-
tions of so many different parts of the body to andrase or
gynase be of such a character that they lead to the develop-
ment of all the complicated organization of the male or
female, and why should the organization of the two sexes
be so adapted to each other? It is evident that the stimulus
which starts these adaptive reactions does not explain the
fact that they are adaptive. That can be found only in the
teleological nature of the mechanism which is set in motion
by these hormones.

Finally, some of the most remarkable of all individual
adaptations are found in the regulations and regenerations
which follow injury. Many eggs> embryos, and adults have
the power of restoring lost parts and in general of resuming
their typical form after injury. Certain flat worms and

Fitness in the Living World 3 2 7

hydroids may be cut up into minute fragments and each /
piece will give rise to a typical animal. Some eggs may be
broken apart in the two-cell or four-cell stages and each cell
will give rise to a whole individual. Many lower animals
such as newts, crayfish, and worms have this power to a very
marked degree. The legs of a newt or crayfish may be cut
off again and again and yet maybe replaced after each ampu-
tation. In the regeneration of the legs of crabs, Morgan has
shown that those legs which are least liable to injury regen-
erate as readily as those which are most liable to be lost. If
the lens in the eye of a newt is removed, it will regenerate
more or less perfectly. Such individual adaptations cannot
be explained as the result of the inherited experiences of
former generations, since the injuries are frequently of such
a kind that they could never have occurred in nature.

Higher animals do not have such extensive power of re-
generation, but every living thing has this power to a cer-
tain extent. Human beings cannot regenerate limbs or other
complex parts, but they have the power of healing wounds
and making repairs, otherwise cuts and other little injuries
would prove fatal.

These individual adaptations are only samples of innum-
erable others that could be cited; indeed, individual adapta-
tions are almost if not quite as numerous as racial ones, and
they are even more mysterious and wonderful, since nothing
in the world seems more inexplicable than the ability of an
organism to respond in a useful and apparently purposive
way to conditions which it has never experienced before and
which in some instances even its ancestors could never have
experienced in all their past history.

LECTURE II
THE MECHANISM OF ADAPTATION

THE wonderful adaptations of organisms to their en-
vironments, of structures to habits, of responses to
needs, of means to ends, have ever been and still are the
greatest problems of biology. From the time of the early
Greek philosophers to the present day, the mystery of life
has centered to a large extent in this great problem of how
organisms came to be so marvelously adapted, in structures
and functions, for their preservation and welfare. Aristotle
maintained that the essence of a living thing is its fitness,
and after centuries of observation, experiment, and theoriz-
ing we must still say that one of the most mysterious and
inexplicable phenomena in nature is the capacity of the
lowest plants and animals, as well as of the highest, to re-
spond to external conditions and stimuli in a useful and an
apparently intelligent and purposive way, although it is
certain that conscious intelligence and purpose are not usu-
ally involved.

How have lowly organisms learned to utilize processes
of chemistry and physics so subtle in character that intelli-
gent man after centuries of civilization has come only
to the place where he can appreciate these processes but
cannot duplicate them? How have those units of living
matter, the cells, come to have complex ideological mechan-
isms for assimilation, growth, and division, for secretion,
contraction, and sensation? How can we explain the origin
of multitudes of inheritance units, their location in the
chromosomes, the wonderful mechanism of mitosis for the
precise division and distribution of these chromosomes to all

3*8

The Mechanism of Adaptation 329

the cells of the body; and how explain the union of homolo-
gous maternal and paternal chromosomes in synapsis and
their unique method of separation in the reduction division,
upon which processes the phenomena of Mendelian inheri-
tance depend? How is it possible to explain the adaptive
mechanisms of the egg and sperm and of the processes of
fertilization? How can we explain the teleological character
of embryonic development, in which the end is apparently
in view from the beginning? How is it possible to account
for the adaptive tropisms, reactions, and instincts of ani-
mals, the complicated but delicately adjusted relationship
between different individuals and species, their ingenious
means of defense and offense and the surprising efficiency
of the living machine? Finally, is it possible to find any
natural and causal explanation of the adaptations of indi-
viduals to conditions which neither they nor their ancestors
have ever before experienced?

The list of such fitnesses is well-nigh endless, and the
question of their origin forms one of the most striking and
fundamental problems of biology. It may be necessary for
the biologist to disregard this problem for the present be-
cause he cannot deal with it, but he should never forget
that it is a real problem and challenges scientific explanation.
This subject is undoubtedly a dangerous one for the scien-
tist, full of pitfalls for the unwary and with many alluring
calls to metaphysical speculation; but it lies in the back-
ground of every biological problem. As Professor W. K.
Brooks taught, "Life is response to the order of nature,"
and it is the element of useful and apparently purposive
response which more than anything else distinguishes the
living from the lifeless, and separates the methods and re-
sults of biology from those of chemistry and physics.

Innumerable attempts have been made by philosophers

33° Problems of Organic Adaptation

and biologists to find an explanation for adaptation. One
need only enumerate the "supernatural design" of theolo-
gians, the "perfecting principle" of Aristotle and Nageli,
the "indwelling soul" of Plato and Bruno, the "active teleo-
logical principle" of Kant, the "unconscious purpose" of
Hartmann, the "vital activity" or "vitalism" of Bunge,
Wolff, and Virchow, the "will" of Schopenhauer, the "elan
vital" of Bergson, the "entelechy" of Driesch, the "archaes-
thetism" of Cope, the "desire" or "need" of Erasmus Dar-
win and Lamarck, and finally Charles Darwin's "natural
selection," to indicate over what a wide field these attempted
explanations have ranged. All of these proposed explana-
tions may be classified as natural or supernatural, or more
accurately as mechanistic or vitalistic. The former presup-
pose only natural forces and processes in the regular se-
quence of cause and effect; the latter assume that some form
of will or purpose is present as an uncaused cause which lies
outside the field of scientific inquiry.

If for the present we pass over those views which attempt
no casual explanation, but merely restate the mystery in
terms of supernatural design, perfecting principles, or entel-
echies, and those which find the causes of adaptations in
unknown laws of variation or of physiological response,
there remain two attempted explanations of organic fitness
which may be known by the general terms of Lamarckism
and Darwinism, though at present neither of these systems
represents accurately the views of the man whose name it
bears.

/. Lamarckism

Lamarckism attempts to explain racial adaptations as the
result of the inheritance of individual or acquired adapta-
tions; it is assumed that the beneficial responses which are
called forth in individuals by external stimuli are handed

The Mechanism of Adaptation 331

on to later generations by heredity, and in this way racial
adaptations are supposed to have originated. Thus all
racial or inherent adaptations are held to have come from
individual or acquired ones. The increased pigmentation
of the skin of one who is exposed to tropical light is said to
be inherited by his children, and so a dark-skinned race
arises; the stretching of the neck and legs of any animal
that browses on trees is supposed to be inherited, and so
the giraffe was evolved. Such an explanation is so simple
and plausible that it has been widely accepted. Unfortu-
nately for this attractive explanation, there is no evidence
that it is true. The evidences in favor of the inheritance
of any somatic modification are very unsatisfactory, and
when it comes to the inheritance of acquired adaptations,
critical evidence is lacking altogether. For years evidences
of such inheritance have been earnestly sought, but no such
confirmations have been found as would certainly have been
the case if this kind of inheritance were at all common.

On the other hand, there seems to be no reasonable escape
from the postulate that modifications of the germplasm are
produced by environmental influences. The germ-cells, and
more especially the chromosomes and genes, are well pro-
tected from almost every change in the external environ-
ment, but there is an internal environment of body fluids
and of cytoplasmic and nuclear substances which comes into
much more intimate contact with the germplasm, and it
seems necessary to assume that certain changes in this in-
ternal environment may cause changes in the germplasm
itself. Some experimental evidence, especially that of Guyer
and Smith on inherited eye-defects in rabbits, favors this
view.

However, such environmental modifications of the germ-
plasm are not generally adaptive, and the beneficial charac-

3 3 2 Problems of Organic Adaptation

ter of germinal modifications must be explained in some
other way. The assumption that individually acquired adap-
tations of parents are directly inherited by their offspring
and thus become racial is not supported by any critical
evidence.

Furthermore, there are many adaptations that benefit
the species at the expense of the individual. For example,
in many instances the reproductive instincts lead directly
to the death of the individuals concerned; every male bee,
every male and female salmon, goes to its certain death
in perpetuating the species. Such adaptations that are for
the good of the race but lead to the death or injury of the
individual cannot be explained by the Lamarckian theory
that racial adaptations are merely individual adaptations
that have become hereditary.

Samuel Butler, Bergson, Bernard Shaw, and many others
maintain that the evolution of adaptations cannot be ex-
plained except on the basis of Lamarckism. Herbert Spencer
said, "If there is no inheritance of acquired characters, there
is no evolution" ; but it is evident that Spencer did not define
with sufficient clearness what he meant by "acquired char-
acters." In one sense random mutations are acquired char-
acters, but they are not somatic modifications due to use or
disuse. Sumner says, "The imperative demand for directed
germinal variations can be met only by assuming the in-
heritance of acquired characters. . . . Adaptations
have come about not because of their harmlessness but be-
cause of their utility." But in spite of theoretical neces-
sities, it is a fact that mutations occur in many directions;
they are multifarious, and in their origin they do not seem
to be directed any more than "the course that the wind
blows." The directing comes after their appearance and
through the elimination of the less fit.

The Mechanism of Adaptation 333

It is a mistake to suppose that Lamarckism explains the
real origin of adaptations; it maintains that individually
acquired adaptations are inherited and thus become racial,
but it attempts no other explanation of the origin of indi-
vidual adaptations than is to be found in "desire," "need,"
or "will." The beneficial character of the response of an
organism to changes in its environment and to use, disuse,
and needs remains as much of a mystery as ever. Lamarck-
ians who have attempted to explain acquired adaptations
have generally appealed to some mysterious principle, such
as unconscious purpose, entelechy, elan vital, or vitalism as
contrasted with mechanism; thus the search for the causes
of acquired adaptations is removed from the field of scien-
tific inquiry. Lamarckism is thus fundamentally non-mech-
anistic, and it is not surprising that vitalists and obscuran-
tists generally should favor the Lamarckian philosophy.

In order to explain racial adaptations, Lamarckism begins
with the unproved and discredited assumption that individ-
ually acquired adaptations are inherited, and in attempting
to explain the origin of individual adaptations it ends in a
fog of obscurantism or in a bog of mysticism.

2. Darwinism

Darwinism, on the other hand, rejects the possibility
of the inheritance of such individual or acquired adapta-
tions and maintains that there is no genetic connection be-
tween racial and individual fitness. It holds that all racial
adaptations are due to (i) multifarious variations (muta-
tions) among offspring and (2) the elimination by natural
selection of those that are poorly adapted. It will be seen
that all adaptations that are for the good of the species
rather than of the individual admit of no other natural ex-
planation, for such adaptations could not have arisen from

334 Problems of Organic Adaptation

the beneficial responses of individuals, as Lamarckism as-
sumes, since they benefit the species at the expense of the
individual.

The probabilities are distinctly favorable to these two
fundamental propositions of Darwinism. We know that
mutations occur in many directions, and that most of them
are not beneficial. We know that the more injurious they are
the earlier the individuals possessing them are eliminated.
There is an immense elimination of germ-cells ; among mam-
mals not one spermatozoon among billions ever fertilizes
an egg, and not one egg in thousands matures and is fertil-
ized; and while it must often happen that the fittest perish
along with the most unfit, still it is highly probable that on
the whole the germ-cells that are fertilized and begin to
develop are among the fitter. There is a large elimination
of embryos and larvse; among many animals thousands
perish for every one that survives; and again, it is most
probable that on the whole and in spite of individual excep-
tions it is the fitter that survive. Many young and sexually
immature individuals die for every one that arrives at sexual
maturity, and here also the survivors are in general the
fitter. There is thus an immense elimination of individuals
in every generation before they reach the period of repro-
duction, and most of this elimination is wholly unseen and
unknown by the casual observer of nature.

On the whole, much of this elimination is discriminative ;
there is universal elimination of the most unfit and, in gene-
ral, survival of the better fitted. It is true that in many
catastrophes destruction is wholly indiscriminate and the fit
and unfit perish together. Even in the more usual forms of
elimination, it does not happen that in every generation and
in every individual instance the fitter survive and the less
fit perish; but if this happens in the majority of cases, it

The Mechanism of Adaptation 335

will in the course of time bring about the diminution of un-
fitness and the general prevalence of fitness. Darwin showed
in masterly manner that the greater elimination of unfit
individuals in each generation and the more general preser-
vation of better fitted ones would gradually improve the
standard of fitness until finally such exquisite adaptations
as are found in the eye, for example, might be reached. This
seems to me to be the crowning glory of Darwin's great
theory; it is not so much its species-forming power which
impresses one as its ability to explain on simple and natural
principles very many of the wonderful adaptations of the
living world.

3. Mutation Theory

The mutation theory has to a certain extent changed our
point of view regarding adaptations as it has also regarding
species formation. Neither of these phases of evolution
can any longer be regarded as the result of minute varia-
tions which persist and replace ancestral forms, if they are
infinitesimally better adapted, but mutations may represent
relatively large changes both in form and usefulness. They
occur in many directions and are usually non-adaptive and
are frequently positively injurious. The latter are quickly
eliminated in a state of nature, but indifferent mutations
may persist, and it is no longer necessary to assume, as older
Darwinians did, that every structure of an organism is of
some benefit to its possessor; on the contrary, it appeared
without reference to its usefulness or its uselessness, and it
persists only if it is not injurious.

Preadaptations. — In applying the mutation theory to the
explanation of adaptations, Cuenot has proposed a modi-
fication of the Darwinian theory which he calls "preadapta-
tion." Mutations which are injurious or indifferent in the

33^ Problems of Organic Adaptation

environment in which they arise may be well fitted for some
other environment and will persist if they can find that other
environment. Thus white insects or spiders, which probably
originally appeared as sudden mutations, are badly fitted to
live on a dark object, since they are so conspicuous; but
they are well fitted to live on a white background — for ex-
ample, white flowers. Their white color was not acquired
by a long and slow process in order to fit them to live on
white flowers, but white mutants appeared suddenly and
then found, by a process of trial and error or by natural
selection, an environment for which they were suited. Loeb
has shown that fish with degenerate eyes may be produced
by hybridizing two species with normal eyes or by keeping
normally fertilized eggs at a temperature of 2° C. for
several hours after fertilization. Such fish were not slowly
adapted to life in caves or dark places, but, since they stand
a very unequal chance of survival in competition with see-
ing forms in the light and probably an equal chance in the
dark, they can survive only in dark places. Thus the blind
fauna of caves was not made for life in the dark, but blind
or nearly blind animals found in caves an unoccupied place
in nature where seeing did not offer any advantage. In
short, the adaptation was present before its fitness was dis-
covered by its possessor ; the environment did not make the
adaptation but merely revealed it. This is, as I understand
it, the same conception which has been called by ZurStrassen
"organized seeking."

Cuenot cites as instances of such preadaptations the fol-
lowing cases among many others : Any beneficial change of
food or habitat, such as the turning of certain butterflies
or moths from particular species of flowers which they ordi-
narily frequent to other species; or the newly acquired
habits of the ground parrot (Nestor notabilis) of New

The Mechanism of Adaptation 337

Zealand, which was originally an insect-eating and fruit-eat-
ing bird, but which has become more or less carnivorous
since rthe introduction of sheep into that country; it was
evidently well fitted, or preadapted, for this new kind of
food even before the food appeared. All such fitnesses were
developed without regard to their later use ; they are there-
fore preadaptations.

Cuenot further points out that such preadaptations, or
fortuitous conjunctions of favorable environment and char-
acters preadapted to this environment, have been an impor-
tant factor in progressive evolution. For example, the ap-
pearance of several great classes of the animal kingdom has
followed the occupation of a place, either unoccupied or
peopled by an inferior group not able to resist the invasion.
Thus shallow-water fishes have given birth by mutation to
amphibians capable of living in a merely humid environment,
thanks to their aerial respiration and walking limbs. From
these issued reptiles which occupied dry regions; their hard
skin, digits armed with claws, internal fecundation and large
eggs, capable of direct development, permitting the omission
of an aquatic stage, were preadaptations necessary to this
change of habitat. Birds, derived from reptiles, peopled
the unoccupied realms of the air owing to their preadapta-
tions for flight. Mammals derived from primitive reptiles
were able to replace these because of their intra-uterine
development, maternal protection of the young and constant
temperature. Man has been able to prevail over preceding
forms because of his superior brain — all these fitnesses being
preadaptations.

This theory of preadaptation is evidently a modification
and extension of the Darwinian doctrine to the origin of ad-
aptations, as the mutation theory is an extension of that doc-
trine to species formation; it is merely a variant on the
theme of natural selection.

3 3 8 Problems of Organic Adaptation

4. Individual Adaptations

But while Darwinism as thus expanded is able to explain
the origin of racial or inherited adaptations, it does not,
as ordinarily understood, succeed in explaining the numerous
and equally remarkable individual adaptations of organisms
any more than Lamarckism does; indeed, some of these
individual adaptations have been held by several recent
writers to be absolutely fatal to both of these theories. For
example, it has been found that if the lens of the eye of a
newt is removed it will be regenerated perfectly within a
few weeks. Now it may be granted that such an injury as
this, involving as it does a very delicate surgical operation,
never took place in nature ; newts may have had their heads
bitten off from time immemorial, but they never had the
lens, removed from the eye except in an experiment directed
by human intelligence; and yet Darwinism in its original
form can explain this regeneration only by supposing that
the loss of the lens has taken place so frequently among the
ancestors of present-day newts that they have become per-
fectly adapted to this injury by the more frequent survival of
those which were inherently capable of regenerating the lens.

Again, the eggs, embryos, or adults of many animals may
be cut or broken into fragments or otherwise injured in
such ways as could never have occurred in nature, and yet
these fragments will, in many cases, give rise to perfect
animals "as if the pattern of the whole existed in every
part." This power of regeneration cannot be the result of
past experience, since there is no constant correlation be-
tween its occurrence and the liability to injury. Other con-
tingent, individual adaptations that are most difficult to ex-
plain are found in the acclimatization of certain organisms
to extraordinarily high temperatures and in the toleration

The Mechanism of Adaptation 339

that may be developed for violent poisons; such acclima-
tization or toleration cannot be due to the elimination on a
large scale of organisms that cannot become adapted, since
in well-conducted experiments few if any of the individuals
perish. In the case of bacterial toxins or snake venom, the
manner in which tolerance to the poison is brought about
is better understood than in the case of other poisons. It
is known that the body that is poisoned forms various anti-
bodies as antidotes to these poisons, and for every toxin,
or at least for every toxalbumin, its^particular anti-body;
but why a particular toxin causes the formation of its one
appropriate antitoxin is a mystery. Many of these toxins
are of such a sort that it is perfectly certain that the im-
mediate ancestors of the individuals poisoned could never
have had experience with them, as, for example, in the case
of guinea-pigs innoculated with cobra venom; and yet the
response is as perfect as it could be if it had been due to
long experience. Many other similar cases might be cited,
but these are enough to indicate how difficult it is to find a
natural explanation for these individual, contingent adapta-
tions. Indeed, it may be said that the apparently intelligent
and purposive response of an organism to a stimulus or
environment which it or its ancestors have never experienced
before is one of the most important and mysterious problems
of biology.

Both Lamarckism and Darwinism hold that racial adap-
tations are due to experience ; Lamarckism, that they are the
directly inherited effects of individual experience; Darwin-
ism, that they are the indirect results of ancestral experience
operating through the presentation of many variations to
the action of natural selection and the survival of the better
adapted. Neither of these theories explains sudden adapta-
tions of individuals to conditions never experienced before.

34° Problems of Organic Adaptation

It has sometimes been said that while racial adaptations
are due to natural selection, individual adaptations are due
to the "plasticity" of the organism; but this is merely seek-
ing refuge in a name. Plasticity is only passivity and is no
explanation at all. It has also been suggested that individual
adaptations are problems of development rather than of
evolution, of physiology rather than of phylogeny. But
this distinction also is nominal rather than real, for evolu-
tion is only one form of development, and phylogeny no less
than ontogeny must be based on physiological processes. It
is true that individual adaptations are things with which
we can deal directly by experimental .methods, whereas
racial adaptations were established in the more or less dis-
tant past and are not readily submitted to experimental
tests. Therefore we ought to know more about the causes
of individual adaptations than of racial ones, but hitherto
attention has been focussed largely upon the latter and rela-
tively little study has been given to the former. One of the
greatest needs of biology is for more detailed and accurate
information regarding individual adaptations; we must
know exactly what happens in each case — the physiology
of the response irrespective of its usefulness — and then per-
haps the latter may find an explanation.

Many of these physiological processes are in a certain
balance with one another or with the environment, and when
this balance is disturbed there is a compensatory regulation.
For example, a muscle that is neither increasing nor decreas-
ing in size receives a certain amount of blood; increased use
of this muscle is balanced by an increased flow of blood,
and decreased use leads to a decrease in the blood supply;
correspondingly, the muscle increases or decreases in size.
Similarly, if one kidney is removed the one that remains has
to perform the functions of two, and it receives more blood

The Mechanism of Adaptation 3 4 l

and grows in size. If much blood is lost in hemorrhage the
activity of the blood-forming organs is increased, and they
send more corpuscles and plasma into the circulation; for
there is a certain equilibrium between the activity of the
blood-forming organs and the quantity of blood in circula-
tion. If white corpuscles are destroyed by x-rays the lymph-
oid tissues are stimulated to send an excess of leucocytes
into the blood, to compensate this deficiency.

This tendency to equilibrium is probably one of the most
important physiological processes in the regulations and
adaptations of organisms. A similar tendency is found in
the inorganic world; when the osmotic pressure between
two fluids separated by a permeable membrane is unequal,
equilibrium is automatically restored; when the gas tension
differs on two sides of a permeable membrane, diffusion oc-
curs through the membrane until the tension is equal on both
sides; when the oxygen or carbon-dioxide tension in the
blood differs from that in the tissues or in the lungs, there
is an exchange of gases until equilibrium is reached; a chemi-
cal reaction proceeds in the direction of equilibrium, and if
an excess of products is formed in one direction the reaction
may sometimes reverse and go in the other direction until
equilibrium is restored. Such cases seem to be analogous
with the compensatory regulations of organisms, but the
balance between one physiological process and another or
between the organism and the environment is not only vastly
more complex than these inorganic equilibria, it is self-pre-
servative and useful; and it is this quality of usefulness or
fitness for which we are seeking an explanation.

It is possible that some of these individual adaptations
belong to the fundamental and original properties of living
things and as such are not to be explained by any theory of
evolution ; for it must not be forgotten that organic evolu-

342 Problems of Organic Adaptation

tion is a theory of transmutation which undertakes to ex-
plain the diversities which exist in the living world, but not
the original properties of life. It undertakes to explain the
various forms of adaptation found among organisms, but
not organic adaptability. It may be that regulation or
regeneration is one of the fundamental physiological prop-
erties of living things, and that it belongs in the same cate-
gory with assimilation, growth, metabolism, reproduction,
and irritability — properties which are found in the lowest
organisms as well as the highest, and which can therefore
be left out of the list of things which organic evolution may
reasonably be expected to explain. But this would certainly
not apply to peculiar, individual adaptations such as have
been named. The origin of these must be explained no less
than the origin of particular racial adaptations. Moreover,
it is incredible that things so much alike as racial and indi-
vidual adaptations should be due to wholly different causes.
It seems, therefore, that while natural selection is a fairly
satisfactory explanation of racial adaptations, it does not,
in the form proposed by Darwin, furnish a satisfactory ex-
planation of individual adaptations, and this has led several
biologists, notably Wolff and Driesch, to the conclusion that
Darwinism "fails all along the line," while many who are not
biologists have hailed with joy what they regard as the
"death of Darwinism." But this conclusion is certainly un-
warranted and extreme. There are many racial adaptations,
as we have seen, which are beautifully explained by the
Darwinian theory, and it is certainly premature to abandon
hope of explaining individual adaptations by a similar prin-
ciple.

5. Intra-personal Selection

Weismann recognized that natural selection as set forth
by Darwin was not a satisfactory explanation of all phe-

The Mechanism of Adaptation 343

nomena of evolution, and especially of the degeneration and
disappearance of useless parts and the concordant modifi-
cation of numerous parts of the organism. In order to
explain these he proposed to extend the principle of natural
selection from individuals or persons ("personal selection"
or "Darwinism" in the strict sense) to organs and tissues
("histonal selection" of Roux), and even to germinal units
such as determinants and biophores ("germinal selection").
This hypothesis as originally proposed was open to many
and serious objections. It is impossible to hold with Weis-
mann that there is a struggle between germinal elements for
food, and that the weaker ones are starved and eliminated
in this struggle; but we are on safe ground when we affirm
that natural selection is operative at every stage in develop-
ment from the earliest steps in the formation of the germ-
cells up to the adult condition. Not even the most radical
critic of Darwinism doubts that animals which cannot live
die. No one doubts that this is true also of individual cells
as well as of persons: What reason is there to suspect that
it is not also true of parts of cells, such as plastids, nuclei,
chromosomes, chromomeres, and even genes? We know
that many young forms perish before reaching maturity,
that numerous organisms never develop beyond embryonic
stages, that multitudes of germ-cells perish, and that, in
general, elimination is much more severe in the earlier than
in the later stages of ontogeny. We know that in the life of
higher organisms many kinds of cells are continually dying
and being replaced by others; so far as epithelial, glandular,
and blood cells are concerned, we may say with St. Paul,
"We die daily." The death of cells is frequently selective;
for example, it is said by medical authorities that the leuco-
cytes or white blood cells are destroyed in large numbers by
the influenza germ, thus opening the way to infection by

3 44 Problems of Organic Adaptation

many germs, especially those affecting the respiratory tract.
It is known also that x-rays kill certain cells, particularly
the leucocytes, sooner than others. We know that it is pos-
sible to destroy parts of a cell and yet keep other parts
alive for a time at least; whole chromosomes may be lost
and yet the cell be capable of continued life and division.
What reason is there for supposing that the same may not
be true of the units of which chromosomes are composed,
and even of the genes themselves? If this should be true,
the elimination of the unfit may take place at any stage in
the ontogeny, and the least viable would be those which
disappear earliest and leave fewest traces. The greatest mis-
fits in the world never become visible to the naked eye, for
they never begin to develop. In this way doubtless many
mutations are eliminated before they ever come to light,
and so modifications which are disharmonious disappear al-
most as soon as they occur.

Recent work of Morgan and his pupils shows that there
are inheritance factors or genes which are transmitted in
Mendelian fashion and which cause death either before
development begins or at some time during that process.
These "lethal factors" bring about the complete elimination
• of certain genotypes, so that natural selection may be said
to begin in such cases with the genes themselves. But it may
be objected that such selection is not necessarily adaptive,
that it does not represent the survival of the fittest, since
these non-viable genotypes might have given rise to pheno-
types which were highly adapted to conditions of life if
only they could have lived; but it must not be forgotten
that in order to leave offspring organisms must live, and that
fitness to survive must be found not merely in adult stages
but in every stage leading up to the adult. Those individuals
that leave offspring must be fit at all stages of development

The Mechanism of Adaptation 345

to persist in the conditions in which they are found; those
that leave no offspring may be fit to live, but they are unfit
for the perpetuation of the species, and those that are in-
capable of beginning development are least fit of all.

6. Trial and Error

Such elimination of persons or cells or genes would not,
however, explain individual or contingent adaptations, which
are really only beneficial responses to environmental stimuli
in which no elimination of individuals occurs. It seems to
me that many, perhaps all, such adaptations may find a
mechanistic explanation in the further extension of the
selection principle to the physiological responses of organ-
isms. Herbert Spencer explained adaptive motions on the
principle of "overproduction of movements" and the per-
sistence of those that are beneficial. Darwin suggested this
method of explaining the apparently intelligent behavior of
the earthworm. Lloyd Morgan applied this principle to the
study of animal behavior under the designation of "trial and
error." In a series of masterly works Jennings has proved
that the beneficial responses shown by many lower organisms
may be reduced to this simple principle of "trial and error";
in this way apparently purposive behavior which Binnet
supposed to be due to the relatively complex "psychic life
of micro-organisms" has been shown to be due to a few
simple motor reflexes, which are repeated indefinitely until
they bring the organism into a favorable environment.
Many recent investigators have shown that this principle is
applicable to the behavior of a large number of animals.

This principle of overproduction of movements or of
"trial and error" is in reality the rejection, elimination, or
cessation of unfit responses and the persistence of beneficial
ones. It has hitherto been applied only to motor reactions,

346 Problems of Organic Adaptation

but in 1909 I suggested that it might be applicable to many
other organic reactions. ZurStrassen has generalized this
principle under the title "overproduction of opportunities
(Gelegenheiten)." If this principle should be found appli-
cable to physiological responses in general it would explain
in equally simple manner many apparently purposive re-
sponses which are at present inexplicable. It is known, for
example, that immunity to bacterial or other toxins is not
acquired immediately but only after a certain lapse of time
during which physiological processes are more or less dis-
turbed; there is frequently an increase of destructive me-
tabolism, the body temperature rises, and there are other
abnormal conditions. "Fever is the process of adaptation
to such toxic agencies as can be neutralized by the develop-
ment of anti-bodies" (Adami and McCrea, p. 149). It is
at least possible that during this period the responses to the
toxin are in the nature of trial and error, that many kinds
of anti-bodies are formed, and that the production of useless
kinds gradually ceases while beneficial ones continue to be
formed. This last might be explained as a result of the
establishment of chemical equilibrium, for if many kinds of
anti-bodies are formed and only one is used up in the "fixa-
tion" of a toxin, this one would continue to be formed while
the other kinds would not.

If this suggested explanation of individual adaptations
should prove to be true, it would mean that the living, de-
veloping, reacting organism is like a swimming Paramecium ;
it tries many paths, eliminating or ceasing to follow useless
or injurious ones and persisting in the beneficial ones. Such
an hypothesis implies in many cases the capacity on the part
of organisms to distinguish between harmful and beneficial
conditions, and this capacity is left unexplained. Since it
is present, however, in living things generally, it may be

The Mechanism of Adaptation 347

considered to be one of the original properties of life, and
our inability to explain its origin is not different from our
inability to explain the origin of metabolism, reproduc-
tion, irritability, or of life itself. Thus the simple principle
of overproduction and the elimination of the injurious or
unfit, whether individuals, cells, or physiological responses,
would offer a possible mechanical explanation of both racial
and individual adaptations and of the almost universal oc-
currence of fitness in the living world.

There are, however, certain difficulties which such an
explanation encounters, and there is always left an unex-
plained remainder which for the present at least is inexpli-
cable on purely mechanical principles. One of the most
serious of these difficulties is that the rate of adaptation
does not appear to be proportional to the rate of overpro-
duction and elimination, as it should be if these are the
only causes of adaptation. The rate of adaptation can be
measured by the rate of divergent evolution, that is, adap-
tations in different directions, or by the relative complexity
and perfection of corresponding adaptations in two groups
of approximately equal age. Measured in either of these
ways, we find that the rate and degree of differentiation
and adaptation are not always proportional to the amount
of overproduction and elimination. The rate of repro-
duction and of elimination is lowest in some genera and
classes in which adaptations are most varied and perfect.
For example, compare the rate of reproduction and elimi-
nation in lower animals and plants with that in higher ones.
If the variety or complexity of adaptations is dependent
entirely upon these two factors, why do not bacteria and
protozoa have the most numerous and complex adaptations
of all organisms; or why do not mice greatly surpass ele-
phants in these respects; or grasses, sequoias; or why is not

348 Problems of Organic Adaptation

man one of the least highly adapted of all animals? Cer-
tainly some animals and plants which have the lowest rate
of reproduction and elimination have the highest types of
differentiation and adaptation.

One answer to this argument is that one organism is as
well adapted as another, and that there are no such differ-
ences in fitness as have been assumed. For example, an
amoeba may be as well adapted to its environment and needs
as a man is to his. If one has reference only to the capacity
to survive and leave descendants, this is certainly true. Ev-
ery individual or species that persists must be well enough
adapted to live and multiply. But adaptations differ greatly
in number and complexity in higher and in lower organisms,
just as differentiations do, and, since these adaptations have
arisen in the course of evolution, those animals and plants
that have the more numerous and the more complex adap-
tations must have had a longer course or a more rapid rate
of evolution. However, the duration of evolution cannot
have been longer in higher forms than in lower ones ; if all
organisms have had a common origin, all are equally old so
far as ancestry and evolution are concerned, and if one con-
siders only the different phyla, classes, genera, etc., it is
evident that these are much older in the lower than in the
higher forms.

It must therefore follow that the rate of evolution and
of adaptation has been much more rapid in higher than in
lower organisms in spite of the fact that in general the rate
of reproduction and elimination of persons has been lowest
in those forms in which adaptation has gone farthest and
fastest. A possible explanation of this apparent contradic-
tion of the Darwinian theory is found in the fact that higher
organisms have more different kinds of genes as well as more
differentiated cells and organs than the lower ones, and

The Mechanism of Adaptation 349

even if mutations of genes occurred with equal frequency
in all organisms (which seems improbable), those in which
the genes were most numerous and most differentiated
would furnish the largest number of mutations. If this
should prove true, the rate of mutation should be greatest
in the most highly differentiated organisms. Incidentally,
the fact that the number of mutations is not proportional
to the number of germ-cells that undergo maturation and
fertilization is evidence that evolution and adaptation do
not depend largely upon Mendelian segregation and recom-
bination of genes, and it also indicates that gene mutations
are not limited to the period of maturation of the germ-cells.

In view of the fact, therefore, that there is in general a
much greater overproduction and elimination of individuals
in lower than in higher animals, it is possible to maintain
the Darwinian theory only by assuming that there is a
greater production and elimination of mutants in higher
forms than in lower ones ; if this be true, it would explain on
mechanistic grounds the more numerous and more complex
adaptations of higher as compared with lower organisms.

On the other hand, the more rapid evolution and adapta-
tion of higher animals would be easily explained by Lamarck-
ian principles. If desire and intelligence are factors in evo-
lution, then it should follow that with increasing intelligence
there should be an increasing rate of evolution and adapta-
tion. Certainly these two — intelligence and rapidity of evo-
lution—seem to be associated, but whether as cause and
effect we cannot say. Evolution has undoubtedly led to intel-
ligence; has intelligence in turn affected evolution?

Finally, whether the Darwinian theory, as thus expanded,
is capable of explaining all the fitnesses of organisms or not,
it does succeed as no other theory does in offering a casual
or mechanistic explanation of very many of these wonderful

35° Problems of ^Organic Adaptation

phenomena. The development of particular structures and
functions fitted to particular conditions of life, such as
organs of locomotion, sensation, respiration, digestion, of-
fense, and defense, and all the multitudes of diverse forms
and ways in which organisms are fitted to carry on the fun-
damental properties of life amidst the most varied condi-
tions— these adaptations we may reasonably expect a theory
of evolution to explain, and it is the crowning glory of
Darwin's theory that it is, on the whole, able to explain
them.

In the preface to his "Vortrage iiber Descendenz-theorie"
Weismann says : "The selection principle controls in fact
all categories of life units. It does not create the primary
variations, but it does determine the paths of development
which these follow from beginning to end, and therewith
all differentiations, all advances of organization, and finally
the' general course of development of organisms on our
earth, for everything in the living world rests on adapta-
tion." I have here proposed that the selection principle is
also applicable to physiological reactions as well as to vital
units, that it lies at the basis of behavior as well as of
bodily structure, and that even instinct, intelligence, and
purpose are themselves the residuum that is left after the
elimination of unfit responses. The selection principle is
the only causal and intelligible explanation of all forms of
adaptation, and if we reject it we can turn only to non-
mechanistic explanations.

LECTURE III
MECHANISM, VITALISM, AND TELEOLOGY

MANY non-mechanistic explanations of organic adap-
tations have been proposed, but they all agree in
this — that they attribute organic structures and functions,
especially those that are directed to particular ends, to some
sort of will which is present as an uncaused cause, either in
some supernatural being or beings, in the universe as a
whole, or in organisms themselves.

Primitive people have generally regarded all the activities
of nature as expressions of will, and a similar view has been
maintained by certain philosophers even in modern times.
As the only cause of his own actions which the primitive
man knew was his will, so he attributed all activities every-
where to will. Even inorganic nature was personified, not
merely poetically, but actually; winds and waves, lightning
and thunder, rain and snow, the regular succession of day
and night, of seed-time and harvest, of life and death, were
presided over by certain deities. Of course the actions of
all animate things were supposed to be voluntary; their wills
moved their bodies and directed their activities to desired
ends.

But step by step, before advancing knowledge of nature,
supernaturalism withdrew from ordinary phenomena until
it dwelt only on the misty mountain tops of origins and crea-
tions. Likewise the voluntaristic conception of inorganic
phenomena was gradually abandoned, though it has long
persisted, and in a rather obscure form still persists, as an
explanation of vital phenomena, and especially of organic
adaptations.

35*

35 2 Problems of Organic Adaptation

1. Supernatural Design

It was the fitness of living things which furnished the
stock argument for the doctrine of supernatural design in
nature. Since these fitnesses are evidently purposive, and
since it is no longer credible that intelligent purpose is to
be found in the simplest plants and animals, it was argued
that an intelligent Designer must have supernaturally cre-
ated each and every one of these adaptations for the specific
function which it now performs. This doctrine reached its
climax in the Bridgewater Treatises, in which natural his-
tory became largely a study of the designs and purposes of
the Creator as revealed in his creatures, and biology was
made to serve as the handmaid of theology.

But although adaptations are very general they are not
universal, and although they are frequently very efficient
they are not divinely perfect; indeed, all gradations of fit-
ness are found in nature from a high degree of perfection
to positive unfitness, and if all of these are the products
of supernatural design some of them show more than human
bungling. Furthermore, one "design" is frequently pitted
against another; the parasite is exquisitely, one might sus-
pect infernally, "designed" to prey upon its host, and the
beast of prey upon its victim, but on the other hand the
host is fitted to resist the parasite and the victim to escape
its enemy. If adaptations are supernatural designs, they
must be the designs of many intelligences working at odds
rather than of one, and their prevalence in the living world
would indicate that there are relatively few phenomena that
are natural. Finally, the "frivolities of teleology" were
carried to such an extent that they rendered the doctrine of
the supernatural origin of every adaptation not only incred-
ible but even ridiculous. And then came Darwinism, which

Mechanism, Vitalism, and Teleology 353

finally and forever put an end to this extravagant doctrine.
"Bridgewaterism is dead." As Darwin says, "There seems
to be no more design in the variability of organic beings and
in the action of natural selection than in the course which
the wind blows." The adaptations of organisms are natural
and not supernatural phenomena, and their causes are to be
found, not in the individual creative acts of some infinite
Designer but in natural forces and conditions. It may be that
these forces and conditions are at present unknown and their
method of action mysterious, but at least they are natural,
unless all distinctions between nature and the supernatural
are to be abandoned. Certainly the fertilization of an egg,
the development of an embryo, the formation of an eye,
acclimatization to extreme temperatures, tolerance for poi-
sons, repairs of injuries, etc., are natural phenomena, and
neither religion nor science, poetry nor truth, are served by
denying this fact.

2. Vitalism

At present there are few if any defenders of the dogma
that each and every adaptation was supernaturally created
for the purpose which it now serves, but there are many
who maintain that living things contain some sort of intel-
ligence, will, or soul which directs their activities to desired
ends. The phenomena of life are so mysterious and won-
derful and so different from inorganic phenomena that to
the great majority of mankind it seems incredible that they
should be the effects of purely mechanistic causes. Accord-
ingly from time immemorial the activities of animals and
plants have been attributed to some mysterious vital force,
anima, spiritus rector, unconscious purpose, or will, which
is wholly different from the causes of inorganic phenom-
ena, which lies beyond the reach of scientific investigation,

354 Problems of Organic Adaptation

and which is more inexplicable than the phenomena it is
supposed to explain. To account for the phenomena of life
by ascribing them to vitalism is no more helpful or intel-
ligible than to explain the properties of water as due to
hydrism or of light to photism. These are merely names
without intelligible meaning. Explanations that explain must
be in terms of other and better known phenomena.

In contrasting vitalism and mechanism it should be under-
stood that the term "mechanism" is not used in the sense of
philosophical "materialism" nor of "mechanics" in its nar-
rower physical meaning, but rather to connote the regular
and invariable sequence of cause and effect, or the principle
of causality. Furthermore, it is the function of science to
classify but not to give ultimate explanations of phenomena;
, to explain phenomena only in the sense of reducing them to
common causes, to deal only with proximate causes and
never with final ones. For example, the law of gravity does
not explain the ultimate causes and mysteries of falling
bodies, but it reduces a thousand causes and mysteries to one.
Scientific explanations of life or of anything else attempt
nothing more than this.

The biologist is often asked, either naively or scornfully,
"What is life?" One might as well ask, "What is matter,
mind, energy?" No final and complete answer to such ques-
tions is possible; these fundamentals can be defined only in
terms of their properties and proximate causes. Life is a
complex of many structures and functions associated with
peculiar conditions of matter. It is never manifested except
in connection with protoplasm, "the physical basis of life,"
and this is an organization of many parts. The universal
form of protoplasmic organization is the cell, which is the
smallest unit of structure and function capable of indepen-
dent existence. The most general and distinctive proper-

Mechanism, Vitalism, and Teleology 355

ties of life are : ( I ) protoplasmic and cellular organization,
(2) metabolism, (3) reproduction, (4) sensitivity, (5)
adaptability.

Are these properties explicable in terms of physics and
chemistry, and to what extent may they be duplicated in
not-living matter? Does the law of cause and effect apply
here as elsewhere in nature? Theoretical mechanism would
answer each of these questions in the affirmitive, vitalism in
the negative. But practically and actually, the mechanist
knows that there are many properties and phenomena of
life which cannot at present be explained in terms of physics
and chemistry, though he has faith that they may ultimately
be so explained. On the other hand, the vitalist knows that
the immediate causes of certain life processes are physical
and chemical, though it is always possible to assume that
the more remote causes are not.

Certain simulacra of protoplasm and of cells have been
produced artificially, but they bear only a few resemblances
to the real living substance. Such artificial products show
that some structures and functions of living cells may be ex-
plained in terms of chemistry and physics, but the more we
know of protoplasm and cells the less likely it seems that
it will ever be possible to synthesize them artificially.

For the past two or three hundred years, and ever in-
creasingly up to the present time, physiology has been deal-
ing with the chemistry and physics of living matter, and
especially of metabolism. Since the time of Lavoisier it
has been known that combustion goes on in the body, oxygen
being consumed and carbon dioxide given off, as in combus-
tion outside the body. Digestion is a chemical process which
can be duplicated in the laboratory. Muscular contraction
and even nerve conduction are accompanied by well-known
chemical and physical changes. No one now questions the

Problems of Organic Adaptation

fact that many vital processes may be explained in terms
of chemistry and physics. Even the strongest adherents of
vitalism must recognize the fact that neither matter nor
energy is created or destroyed in an organism, but that
these merely undergo transformations (metabolism). All
energy of an animal comes from its food just as the energy
of an engine conies from its fuel; the vital machine is as
dependent upon food as the engine is on fuel. However,
only the first and last steps in constructive and destructive
metabolism are known; the middle step, assimilation, is
still a good deal of a mystery, but it is probably a chemical
process in which each of the many kinds and varieties of
protoplasm is built up out of the common nutrient materials
through the action of specific enzymes.

The properties of reproduction, irritability, and adapta-
bility are more distinctive of living things and are more
difficult to explain on a physico-chemical basis than is me-
tabolism. Certain analogies to each of these processes are
found in the inorganic world, and certain steps in each of
them are plainly physico-chemical in origin, but it must be
admitted that there is left a large residuum which cannot
at present be explained on mechanistic grounds. However,
much progress is being made in this direction, and this justi-
fies the hope that many more, if not all, vital processes will
ultimately be explained in this way; certainly there seems to
be no justification for abandoning the search for mechanistic
explanations at a time when they are being found as never
before, nor for turning at once from a mechanistic philoso-
phy of life to obscurantism or mysticism. For although
mechanism may not in the last analysis explain vital phe-
nomena, or anything else for that matter, it is evident that
very much of a mechanistic nature remains to be discovered
in organisms, and the great advantage of mechanism over

Mechanism, Vitalism, and Teleology 357

vitalism is not only that it is more intelligible but also that
it encourages scientific investigation, whereas a thorough-
going belief in vitalism discourages research.

Of late several notable attacks have been made upon the
mechanistic conception of life, particularly with reference
to the causes of adaptation. Bergson, Driesch, Noll, Pauly,
Reinke, Schneider, Thomson, G. Wolff and other "neo-
vitalists" hold that many vital processes are indeterminate,
non-predictable, non-mechanistic, and creative ; they attempt
to solve the riddles of life by a direct appeal to mysterious
conditions or principles which are found only in living things.

Bergson's evidence for his elan vital is found in part in
phenomena of parallel or convergent evolution. He main-
tains that, starting from different sources and proceeding by
wholly different routes, organisms may reach the same termi-
nus. For example, he holds that the eye of the mollusk,
Pecten, and the eye of a vertebrate are practically the same
in structure, though they have evolved by wholly different
paths and from wholly different sources; or again, that
societies of ants and of men are fundamentally alike, al-
though they have evolved in entirely different ways. If iden-
tical results can thus come from wholly different causes,
there is scientific indeterminism, and some principle other
than cause and effect must be involved, some form of vital-
ism rather than mechanism.

But neither in the living nor the not-living world do iden-
tical results come from dissimilar causes; in short, conver-
gent evolution does not result in identical structures. When
Mivart denied that homologies are evidences of evolution
and claimed that the eye of a cuttle-fish and the eye of a
vertebrate were homologous, though they could not have had
a common origin, Darwin replied by showing that these two
types of eyes are in no sense homologous; that is, they are

3 5 8 Problems of Organic Adaptation

fundamentally dissimilar though superficially alike. And in
reply to Bergson it may be said that although the eye of
Pecten is in a single feature, namely, the inverted retina,
like the vertebrate eye, it is in other respects fundamentally
different. These eyes are not homologous and Bergson's
contention is groundless.

Neither are the similarities between societies of ants and
men, and many other examples of a like nature which are
cited by Bergson, real homologies or examples of convergent
evolution. The similarities which are present are merely
such as are due to principles of universal application, such
as the extension of differentiation and integration from indi-
viduals or persons to colonies and states. Practically all
of Bergson's cases of convergent evolution are of this sort.
They indicate only the essential unity of all living things,
that certain properties are characteristic of all life and are
present in the simplest as well as in the most complex organ-
isms. They certainly do not prove that life processes are
indeterminate or that identical results may follow different
causes, and therefore that vital activity is non-mechanistic.

It is true that it is often impossible to predict what living
things will do, but this is probably owing to the fact that
the factors involved are very numerous and complex. When-
ever the number of factors is large and the times and cir-
cumstances of their action numerous, it is difficult to predict
results, as is seen for example in so simple a phenomenon
as the weather. This is especially true of the behavior of
higher animals, for here the number of factors is much
greater than in many inorganic phenomena and the inter-
actions of these factors are most complex. Professor W. K.
Brooks used to comment upon the ease of predicting what
would happen when you kick a stone, as compared with the
difficulty of predicting the results of kicking a dog. In the

Mechanism, Vitalism, and Teleology 359

latter case one needs to take into account many hereditary
and environmental factors; one needs to know the breed
and size of the dog, whether he is at home or not, whether
the one who kicks is a stranger or not, etc. There is good
reason to believe that when all these factors are taken into
account the results in the case of the dog would be as pre-
dictable as in that of the stone. Certainly none of the cases
cited by Bergson proves that the activities of animals are
indeterminate and non-mechanistic.

Driesch also has maintained that adaptive responses in
general cannot be explained by mechanistic science. His first
proof of vitalism is that a living thing is a "harmonic, equi-
potential system" ; that is, "the pattern of the whole exists
in every part," and under suitable conditions a fragment of
an egg, embryo, or adult can give rise to a typical whole.
Likewise, when the cells and nuclei of segmenting eggs are
forced out of their normal positions by pressure normal
development may result, and Driesch holds that neither
cytoplasm, nucleus, nor medium are the causes of differentia-
tion, but that "the fate of a part is a function of its position"
in the whole, and that "any part is capable of any fate.""
Some organisms may be cut up in the three dimensions of
space and yet each fragment that is sufficiently large may
give rise to a complete organism like the original one. It
is inconceivable, he says, that any machine could be broken
up in this way and yet the parts be capable of becoming
complete. He therefore concludes that something, not
mechanistic nor causal, lies in the background of develop-
ment; this something he calls, in the language of Aristotle,
"entelechy."

His second proof of vitalism is drawn from the genesis
of this complex equipotential system. It is absurd to sup-
pose, he says, that any machine could give rise to such a sys-

360 Problems of Organic Adaptation

tern, and again he invokes the aid of "entelechy." Finally,
he finds a third proof of vitalism in the field of behavior,
or what he calls the "individuality of correspondence be-
tween stimuli and responses." In such cases something non-
mechanistic interferes when the good of the organism re-
quires it, and this something, which resembles the "indwell-
ing soul" of Plato, he calls "psychoid." In short, Driesch's
three "proofs" of vitalism are all based upon adaptive re-
sponses.

However, all the parts of living things, whether eggs,
embryos, or adults, are rarely, if ever, equipotential. Even
parts of the embryos of the sea-urchin, upon which Driesch
did much of his work and based most of his conclusions,
are not equipotential in the chief axis; that is, fragments
from the upper or lower poles are not capable of regenerat-
ing a whole embryo or larva. Fragments of the hydroid
Tubularia are not equipotential so far as proportionality is
concerned (Child). Regeneration in the ascidian Clavelina
is complicated by degeneration, regeneration, and budding
(ZurStrassen). The different cleavage cells of the eggs of
mollusks, annelids, and ascidians are not equipotential, and
when one of these cells is destroyed its function is not taken
by other cells, but the embryo remains incomplete (mosaic
development).

When Driesch maintains that neither cytoplasm, nucleus,
nor medium is the cause of differentiation what can he
mean? All of these factors are in varying ways and de-
grees the causes of differentiation. And when he asserts
that it is inconceivable that any machine could be broken up
in the three dimensions of space and the fragments still be
capable of producing whole machines, or that it is absurd
to suppose that any machine could give rise to an equipoten-
tial system, it is evident that his conception of a machine is

Mechanism, Vitalism, and Teleology 361

too narrowly limited to those of human invention. The liv-
ing machine is not a single one, as is an engine or a watch,
but it'is composed of machines within machines. Every liv-
ing body is composed of cells within which are nuclei. The
visible differentiations of a body are developed from the
portion of the cell outside of the nucleus, but always under
the influence 'of the nucleus. The nucleus itself rarely under-
goes differentiation, so that there is in every such nucleus
a complete machine which under certain conditions may be
capable of developing a complete organism, as in the case
of development from an egg cell. If this nuclear machine
is fragmented or destroyed no regeneration is possible.
Therefore the machine-theory of organization does not
fail in this case; only Driesch's conception of the vital ma-
chine fails because the real organism is more complex than
he supposed.

But even granting Driesch's claims that organisms are
equipotential systems capable of complete regeneration
after injury, that they differ greatly from machines of
human invention, and that they generally respond benefi-
cially to stimuli, it does not follow that they are in any
respect removed from the field of mechanistic causality.

In the works of Bergson, Driesch, Thomson and other
"neo-vitalists" hundreds of pages are devoted to labored
refutations of mechanistic explanations of life and to elo-
quent presentations of mystical, allegorical, and unintelli-
gible causes. In a notable contribution by Jennings1 the
ground is cleared of mere verbiage and the solid founda-
tions of a mechanistic conception of life are laid in eighteen
pages. Jennings shows that diversities in life phenomena
are accompanied or preceded by diversities in materials,
functions, and structures, and that they are not indeter-

1(<Life and Matter." Johns Hopkins Univ. Circ., 1914.

362 Problems of Organic Adaptation

minate or capricious. He points to the very significant fact
that there is no evidence of life apart from protoplasm, and
that such phenomena as development, adaptation, reason,
and purpose are not annulled if they are found to be bound
up with matter, for it is no more extraordinary that they
should be associated with matter than that they should be
separate from it.

In living as in lifeless things, mechanistic factors are not
merely additive as Driesch maintains, but they are fre-
quently creative. In chemical compounds new qualities ap-
pear which were not present in any of the elements entering
the compounds. No one could predict beforehand the quali-
ties of water from the properties of hydrogen and oxygen,
and in general one cannot predict the results of combinations
before they have been learned by experience. The fact that
one could not predict consciousness from a knowledge of
the organic or inorganic constituents of the body is not
fundamentally different from these other cases in which new
things are formed by new combinations. The "creative evo-
lution" of Bergson is not different in principle from "crea-
tive synthesis," which is found everywhere in the living
and the lifeless worlds; it is therefore no proof of vitalism.

The new vitalism no less than the old has failed at every
point to establish its main proposition, namely, that the
reactions of organisms are not causal, and that they require,
in order to explain them, a special principle which is lacking
in the inorganic world and which is non-mechanistic in action
and wholly unrelated to the principle of cause and effect.
This is not to deny that there may be a teleological principle
in all nature, but rather to affirm that there is no sufficient
reason for supposing that in this regard the living world
differs fundamentally from the lifeless.

Mechanism, Vitalism, and Teleology 363

3. Mechanism and Purpose

The only mechanism of adaptation that has ever been
suggested is the elimination of the unfit and the persistence
of the fit. Inherited or racial adaptations may be explained
as the result of the elimination of unfit individuals ("per-
sonal selection" or "Darwinism" in the strict sense), while
acquired adaptations and useful responses to new conditions
can be accounted for by the elimination of unfit structures
and functions within the individual (intra-personal and re-
actional selection). Thus the simple mechanical principles
of overproduction of varied individuals or reactions and the
elimination of the less fit furnish a mechanistic explana-
tion of all kinds of fitness in the living world.

But in man at least, and probably also in some of the
higher animals, there is conscious purpose, and the behavior
of many lower animals suggests that they also possess some-
thing similar to human purpose, though it is probably not
accompanied by consciousness. If conscious purpose has
evolved during the course of evolution, as it certainly de-
velops during the individual development of man, do we
not here find a phenomenon which cannot be explained as
due to mechanistic causes? And if conscious purpose is non-
mechanistic in its origin, is it not probable that "unconscious
purpose," such as is manifested in the many apparently pur-
posive responses of digestion, respiration, circulation, devel-
opment, regulation, and the adaptive behavior of lower or-
ganisms, is also non-mechanistic? In short, if we approach
this problem of fitness from the standpoint of human con-
sciousness rather than from that of the physiology of the
lowest organisms, from the top rather than from the bot-
tom, do we not find that the mechanistic philosophy fails
to furnish an adequate explanation? Mechanism must ac-

364 Problems of Organic Adaptation

count for purpose in man, as well as for fitness in lower or-
ganisms, if it is a universal principle.

It is this point of view that gives weight and force to
non-mechanistic philosophy. Any system that denies will
and purpose to man must be false, not only because it con-
tradicts one of the most fundamental facts of consciousness,
one of the most general experiences of men, but also because
it is impractical and unlivable.

If man is the product of mere chance or accident; if as one biologist
has said, "The evolution of consciousness is the greatest blunder in
the universe" ; if men live and die like the beasts and leave only their
bones and implements behind; if life and evolution and consciousness
are purposeless and lead to nothing — if this were the teaching of the
mechanistic philosophy, then certainly it would be true that it debases
man, and destroys the hopes of mankind. The blighting effect of
such a philosophy is that it substitutes blind chance and necessity
for plan and purpose, both in nature and in human life. If there is
no teleology in nature, the course of evolution leading to man and to
consciousness is the result of blind and blundering accident. If there
is no purpose or value in human labor and suffering, life is not worth
living, and the only sane and sensible thing to do is to end it all by
suicide and race extinction.

But there are evidences of teleology in nature and of purpose in
human life. Even struggle, suffering, and death have their value if
in the long course of evolution they lead to progress. Men do not die
and leave only their bones and implements, but "they rest from their
labors and their works do follow them." "Others have labored and
we have entered into their labors." Civilization is what it is today
because of the labor and influence of millions of persons, most of whom
are wholly unknown to us. Only a few men have achieved immortal
fame, but multitudes have contributed to human progress.1

In man at least intelligent purpose exists and must be ac-
counted for. Here is the crucial test of universal mechanism
— the purpose, consciousness, soul of man ! If these psychic
phenomena are not mechanistic in origin some principle
other than mechanistic causality is present in man; and when

'"Direction of Human Evolution," pp. 231, 232.

Mechanism, Vitalism, and Teleology 365

we observe the purposive actions of animals, for example
crows dropping mussels on rocks to break them open, cats
turning buttons to open doors, or horses unlatching gates,
it is evident that we are here dealing with the same funda-
mental problem that we have in human purpose. Finally,
even non-conscious and purely instinctive acts, that are pur-
posive, belong in the same category; for example, the mat-
ing, nest-building, brooding, and care of young on the part
of birds, or similar reproductive habits of mammals, show
instinctive, but not perceptual purpose. In man only, so
far as we know, does purposive action at certain times rise
into the field of consciousness, but most of his activities are
non-conscious, although they are purposive. All such phe-
nomena, from conscious purpose at one extreme to instinc-
tive reactions and to tropisms at the other, seem to be fun-
damentally akin, and if mechanism fails to explain any of
them it probably fails with all ; if tropisms and instincts are
entirely explicable on mechanistic grounds, it is probable
that even perceptual purpose may be so explained.

In commenting upon the fact that adaptations are mech-
anisms for securing the persistence of organisms, Roux1
says: "Persistence is not an aim of living things but an in-
dispensably necessary condition. Life cannot suddenly arise
anew, but if it exists it must be preserved, and so must before
all be capable of persisting, otherwise it disappears. This is
no aim but a direct necessity of its existence."

But after all, the real question is how living things are
able to meet these necessary conditions of life. It may be
granted that adaptations are not caused by conscious aims
or purposes, but their results are much the same as if they
were; they do attain certain desirable ends, and to this ex-
tent they are purposive. But results may be purposive while

'Arch. Entwick. Mech. Bd. 26, 1908.

366 Problems of Organic Adaptation

their causes are mechanistic; the contrary view is due to a
false conception of purpose or of mechanism. There are
good reasons for believing that purpose and will in ourselves
are not uncaused but rather that they are results of ante-
cedent causes ; that they also are links in the chain of cause
and effect, and hence are mechanistic in origin.

We have already found that many of the beneficial re-
sponses of protozoa and germ-cells are the residuum left
after the elimination of non-beneficial responses; in these
cells, however, there is little if any capacity to profit by
experience. On the other hand, a cat that by random move-
ments accidentally unlatches a door and lets itself out, as
in Thorndike's experiment, gradually omits useless move-
ments, remembers past successes, and finally learns to un-
latch the door at once, thus showing intelligent purpose,
developed through the mechanistic process of the elimina-
tion of useless responses. Are intelligence and purpose in
man fundamentally different from this? There is every
reason to believe that human beings arrive at intelligence
and reason by the same process — a process of many trials
and errors, a few trials and successes, a remembering of
these past experiences, and an application of them to new
conditions. All solving of problems, directed thinking and
consecutive reasoning are accompanied by, if they do not
consist in, rapid elimination of unfit ideas and mental activi-
ties. Thus intelligence and purpose in man, no less than fit-
ness in all organisms, may be explained as results of the
elimination of the unfit; they also are adaptations; and for
this reason, if for no other, adaptations appear to be intel-
ligent and purposive.

4. Teleology

Nevertheless, this mechanistic explanation of fitness and
purpose is not complete and many things are left unex-

Mechanism, Vitalism, and Teleology

plained. For example, the mechanism of trial and error by
which Paramecium avoids extremes of heat and cold is
based upon its ability to distinguish between favorable and
unfavorable, or between satisfactory and unsatisfactory,
conditions. In some of the simplest forms of living things
as well as in the most complex this capacity exists, and for
the present at least it cannot be accounted for on mechanis-
tic grounds. Thus in our mechanistic explanation of fitness
we put in at the beginning what we get out at the end,
namely, a capacity to distinguish between the fit and the
unfit, and a tendency to retain the one and eliminate the
other. And so in all mechanistic sciences from mathematics
to biology, we introduce in one form or another in our
factors the qualities which we seek to explain in the end
product. It is said that in some rural districts hogs are
weighed by driving them on to one side of a balanced plat-
form, throwing stones on to the other side until they equal
the weight of the hogs, and then guessing at the weight of
the stones. When we attempt to explain the actual origin of
fundamental qualities by quantitative mechanistic methods,
do we not, with much labor, perform a similar operation?
It is a striking fact that at present it is impossible to explain
the organization of a cell, the potencies of development or
of evolution, or the elements of fitness, purpose, and con-
sciousness on purely mechanistic grounds. "It is because liv-
ing things are irritable, registrative, persistent, variable, that
they have been able to evolve in adaptive ways," but we can-
not explain the fact that they possess these qualities. Thus
we introduce on one side of the equation the equivalents of
the things on the other side which we seek to explain.

In a recent treatise on evolution in its widest aspects,
Macfarlane1 has proposed as one of the principal factors in

"'Causes and Courses of Organic Evolution," p. 628. ,

368 Problems of Organic Adaptation

evolution and adaptation what he calls "proenvironment" ;
this he defines as "the capacity of any organism for perceiv-
ing and then positively growing or moving toward an envi-
ronment that is the most satisfying for it." This capacity
he holds is present in all living things and has its analogue
even in chemical affinity. Certainly when one observes how
almost universally organisms distinguish between benefi-
cial and injurious environments, one is compelled to admit
that some such capacity must be present in all living things,
and that it must be an important factor in the adaptive or
beneficial responses of organisms. Whether it is also a
factor in the evolution of racial adaptations depends upon
the answer to the question whether such individual or ac-
quired adaptations can become hereditary. Macfarlane
takes it for granted that they can be, and he would probably
maintain, though he has not developed this thesis specifi-
cally, that all inherited adaptations were in their individual
origins beneficial or satisfying responses to the environment.
Against this view may be urged all the weighty objections
to the doctrine of the inheritance of acquired adaptations
which are familiar to all biologists. It is difficult if not im-
possible to explain on this ground the origin of numerous
inherited adaptations which are for the good of the species
only and are destructive of the individual; for example,
the peculiar structures, functions, and instincts of worker
and drone bees, which lead to the sacrifice of the indi-
vidual for the good of the colony, cannot be explained by
any form of Lamarckism, but are readily explained by
Darwinism.

According to the Darwinian theory, the guiding and
directing power of selection should be directly proportional
to its severity. If it eliminates only those mutants that are
positively injurious or non-viable, as many adherents of the

Mechanism, Vitalism, and Teleology 369

mutation theory believe, would it be possible to explain such
perfect adaptations as are found, for example, in the eye?
If these be attributed to the chance occurrence of favorable
mutations, do we not place upon chance a perfectly, im-
possible burden when we load upon it not only all the won-
derful adaptations in such an organ as the eye, but also all
the multitudes of adaptations and coadaptations which exist
in every part and function of man or one of the higher
animals?

Most of all, when we turn from analysis to synthesis and
consider the whole course of organic evolution from amoeba
to man, from the simplest motor responses to the develop-
ment of an intellect capable of studying the universe and its
origin, are we impressed with the idea that evolution has
been guided by something other than chance. Progressive
evolution consists in increasing complexity of organization
and in increasing adaptation, to the environment. It is prob-
ably no accident that organization, mutations, and environ-
ment have been so correlated that they have led to the per-
fection of organization and adaptation which we see all
about us. Evolution has not been an eternal seesaw : it has
led somewhere. The fact that organisms can adapt them-
selves to changing environment is no accident; the fact that
environment has so changed as to bring about progress is
no accident. Philosophically, it is difficult to avoid the con-
clusion that evolution has revealed a larger teleology than
was ever dreamed of before — a teleology which differs from
vitalism in that it takes in not only the living but also the
lifeless world.

And yet science cannot deal with teleology but only with
causes and effects and mechanisms; given matter and energy
and life, with all their potentialities, science deals with the
succession of events in evolution, explaining them in, a purely

37° Problems of Organic Adaptation

mechanistic manner. In biology the desire for simple me-
chanical explanations is so great that it often causes us to
minify the difficulties and magnify the successes of such ex-
planations. We may temporarily close our eyes to these
difficulties, but they remain and must be reckoned with.
Few persons have the intellectual honesty of Darwin, who
wrote down at once the objections to his theory as they
occurred to him, lest he might forget them, and who con-
fessed that he never thought of explaining the evolution
of the eye without a shudder. But even if an ultimate
mechanistic explanation of adaptations is not possible, it
does not follow that we must at once resort to an explana-
tion which is either non-mechanistic or supernatural. Many
things which were once supposed to be due to supernatural
causes are now readily explained by natural ones. The ear-
lier students of evolution proposed absurdly simple mechani-
cal explanations of the process. Later these were replaced
by more complex mechanisms, and when these latter fail to
offer a satisfactory explanation the scientific solution must
be sought in more and more complex mechanisms; for
science deals only with mechanisms, and a scientific explana-
tion must be mechanistic.

Some of the world's great philosophers and scientists, from Aris-
totle and Plato to Kant, Schopenhauer, Lamarck, Cope, Bergson,
Driesch, and Henderson, have maintained that the fitness and order
of nature can be explained only by assuming that there is some sort
of teleological principle in nature, which lies back of or runs parallel
with the principle of causality — something which acts more or less
like human will or purpose, and which is itself an uncaused cause
lying outside the field of scientific inquiry.

Kant has expressed this opinion in a well-known passage: "It is
quite certain that we cannot become sufficiently acquainted with
organized creatures and their hidden potentialities by aid of purely
mechanical natural principles, much less that we can explain them;
and this is so certain that we may boldly assert that it is absurd for

Mechanism, Vitalism, and Teleology 371

man even to conceive such an idea, or to hope that a Newton may one
day arise to make even the production of a blade of grass compre-
hensible, according to natural laws ordained by no intention."

Haeckel and other pure mechanists have hailed Darwin as Kant's
impossible Newton of the living world and his theory of "natural
selection" as the purely mechanical principle which accounts for the
adaptations of organisms. ... In the light of Darwin's theory
we see that adaptations are the results of natural causes: the causal
mechanism applies to all the fitnesses of nature as well as to other
phenomena; but back of all mechanism, or running through all
mechanism, is teleology or purpose.

From the standpoint of science and philosophy the origin of this
order and mechanism is the great secret of the universe. Science
deals only with mechanisms, and a purely scientific explanation must
be mechanistic, but there is no mechanical explanation for the ulti-
mate mechanism of the universe; mechanism cannot explain itself.
The mechanism of a locomotive will explain what it does, but it will
not explain its origin nor the purpose which it subserves. The organi-
zation of an animal or plant or egg is said to explain what it does,
but it will not explain the teleological nature of that organization.

Biologists no longer think of any adaptation as having been directly
created for the purpose which it now serves but rather as having been
slowly developed in the course of evolution. Nevertheless, in tracing
an adaptation to its sources we do no more than transfer the origin
of fitness to earlier causes. We may explain the fitness of the eye as
due to its ontogenetic development, and this as due to heredity and
environment, but this does not explain how the potentialities of the
eye came to be in the germ-plasm. We have merely shifted the problem
to an earlier stage. And the same is true of the evolution of eyes:
our explanation of the origin of eyes may be that they are due to
mutation and natural selection, or to the inherited effects of use and
disuse: but in either case we do not explain the fact that eyes were
potentially present in these causes. We have merely shifted the prob-
lem from the fitness of results to the fitness of the causes of those
results: and in spite of Darwin and his great theory, it is still true
that no Newton has yet arisen "to make even the production of a
blade of grass comprehensible, according to natural laws ordained
by no intention."1

In two recent books of great philosophical and scientific
value, Henderson has shown that very many elements of the

'Conklin, "Direction of Human Evolution," pp. 221-224.

3 7 2 Problems of Organic Adaptation

environment are chemically and physically the best possible
for life phenomena. In particular, water, carbonic acid and
the compounds of carbon, hydrogen, and oxygen possess
many unique properties which are necessary to life, and these
substances are better fitted to the life processes than any
other known substances. He concludes, "Therefore the fit-
ness of the environment is both real and unique." The origin
of this fitness of the environment for life "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." And yet he holds that it "is conclusively proven
that the whole process of cosmic evolution from its earliest
conceivable state to the present is pure mechanism." In ex-
planation of this fitness which runs through the whole of
nature, he concludes that it is conceivable that a teleological
"tendency would work parallel with mechanism without in-
terfering with it. The effect of such a tendency working
steadily through the whole process of evolution is also at
least conceivable, however small its bearing upon science,
provided, like time itself, it be a perfectly independent vari-
able, making up therefore, with time the constant environ-
ment, so to speak, of the evolutionary process. This ten-
dency must not be demonstrable either by weighing or by
measuring, else it would amount to an interference with the
mechanistic process, and it must not itself be liable to any
kind of variation whose detection 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 mechan-
ism, only where Bergson1 has shrewdly placed his vital im-
pulse, at the very origin of things, just before mechanism
begins to act. In short, our 'new teleology cannot have

1Bergson places his vital impulse not at the origin of the universe but
only at the beginnings of life. It is a form of vitalism rather than of general
teleology.

Mechanism, Vitalism, and Teleology 373

originated in or through mechanism, but it is a necessary and
preestablished associate of mechanism. Matter and energy
have 'an original property, assuredly not by chance, which
organizes the universe in space and time."1

These important philosophical conclusions supplement but
do not destroy a mechanistic interpretation of nature. If
the chemical and physical characteristics of the environment
had been very different from what they are, life as we know
it could not have existed on the earth, just as it is probable
that life does not exist on the moon because of the absence
of water and of an atmosphere. It does not necessarily fol-
low that the environment was made as it is for the purpose
of supporting life, or that prospective life was a cause of
antecedent environment, but it is impossible to reflect upon
this fitness of the environment and indeed the whole order
of nature without recognizing our inability to explain finally
such phenomena on purely mechanistic grounds.

This conception of a general teleological principle run-
ning through all nature differs from vitalism in that it rec-
ognizes no world-wide distinction between the organic and
the inorganic; both of these belong to the same universe;
in both mechanism is universal, and so also is teleology.
Here is common ground upon which mechanists, vitalists,
and religionists may take their stand; for the thing which
mechanists desire to prove is not the absence of teleology
but the universal presence of mechanism, while the proposi-
tion which defenders of vitalism and of religion are con-
cerned to prove is not the absence of mechanism but the
presence of teleology.

Some of the most profound students of nature from the
ancient Greeks to the present time have thought it necessary
to assume some initial teleological principle. Weismann,

^'The Fitness of the Environment," pp. 307, 308.

374 Problems of Organic Adaptation

whom Bernard Shaw counts the chief of scientific sinners
because of his advocacy of a mechanistic conception of evo-
lution, believed that extreme mechanism was consistent with
extreme teleology; indeed, he maintained* "The most com-
plete mechanism conceivable is likewise the most complete
teleology conceivable. With this conception vanish all ap-
prehensions that the new views of evolution would cause
man to lose the best that he possesses — morality and purely
human culture." And no less a mechanist than Huxley said,
"Perhaps the most remarkable service to the philosophy
of biology rendered by Mr. Darwin is the reconciliation
of teleology and morphology, and the explanation of the
facts of both which his views offer. The teleology which
supposes that the eye, such as we see it in man or one of the
higher Vertebrata, was made with the precise structure
which it exhibits, for the purpose of enabling the animal
which possesses it to see, has undoubtedly received its death-
blow. Nevertheless it is necessary to remember that there
is a wider teleology, which is not touched by the doctrine
of evolution, but is actually based upon the fundamental
proposition of evolution. That proposition is that the whole
world, living and not living, is the result of the mutual inter-
action, according to definite laws, of the forces possessed
by the molecules of which the primitive nebulosity of the
universe was composed."1 And Darwin confesses "the ex-
treme difficulty or rather impossibility of conceiving this
immense and wonderful universe, including man with his
capacity of looking far backwards and far into futurity, as
the result of blind chance or necessity. When thus reflecting
I feel compelled to look to a First Cause having an intelli-
gent mind in some degree analogous to that of man; and I
deserve to be called a Theist. This conclusion was strong in

iHuxley, Collected Essays, Vol. 2, p. 110.

Mechanism, Vitalism, and Teleology 375

my mind about the time, as far as I can remember, when I
wrote the 'Origin of Species' ; and it is since that time that it
has very gradually, with many fluctuations, become weaker.
But then arises the doubt, can the mind of man, which has, as
I fully believe, been developed from a mind as low as that
possessed by the lowest animal, be trusted when it draws
such grand conclusions?"1

Finally, Henderson has summed up his conclusions on this
subject in the following thoughtful sentences: "We may
progressively lay bare the order of nature and define it
with the aid of the exact sciences. Thus we may recognize it
for what it is, and now at length we clearly see that it is
teleological. But we shall never find the explanation of the
riddle, for it concerns the origin of things. Upon this sub-
ject clear ideas and close reasoning are no longer possible,
for thought has arrived at one of its natural frontiers.
Nothing more remains but to admit that the riddle surpasses
us and to conclude that the contrast of mechanism with
teleology is the very foundation of the order of nature,
which must ever be regarded from two complementary
points of view, as a vast assemblage of changing systems,
and as an harmonious unity of changeless laws and qualities
working together in the process of evolution."2

CONCLUSION

The great problems of the methods and causes of organic
evolution and adaptation are slowly being solved. We have
made many false starts and have had to retrace many steps,
but nevertheless much progress has been made along many
lines. Many attractive theories have had their day and are
now abandoned; unfortunately we do not know that many

and Letters, Vol. I, p. 282.
2<The Order of Nature," pp. 208, 209.

3 7 6 Problems of Organic Adaptation

current theories may not suffer a similar fate. But to certain
theories in one form or another we come back again and
again, and always they are more secure. This is especially
true of the underlying idea in the theory of Darwin, that
master of those who interpret Nature.

But whether we have reached any satisfactory solution
of evolution problems or not, we know at least that these
problems are being attacked in the only possible scientific
way, viz., by observation, analysis, and experiment. Doubt-
less some of these great problems will always remain un-
solved, for Nature is infinite. It is not the possession of
perfect truth, but its pursuit, which falls to our lot and fills
up the measure of our lives; and we would not have it other-
wise, "for to travel hopefully is a better thing than to arrive,
and -the true success is to labor."

LITERATURE CITED

BALTZER, F. — Was haben die biologischen Schaften an fester Er-
kenntnis fur die Bildung ciner Weltanschauungen zu bieten?
Referaten der Aarauer Studentenkonferenz, 1920.

BECKER, S. — Seele, Handlung und Zweckmassigkeit in Reich der
Organismen. Ann. des Naturphilos. Bd. 10, 1910.

BENEDICT, FRANCIS G. — Muscular Work: A Metabolic Study with
Special Reference to the Human Body as a Machine. Washing-
ton, D. C, 1913-

BERGSON, H. — Creative Evolution. New York, 1911.

BOVERI, TH. — Die Organismen als historische Wesen. Wiirzburg,
1906.

BROOKS, W. K. — The Foundations of Zoology. New York, 1899.
BUTLER, SAMUEL — Evolution, Old and New. London, 1879.

CHILD, C. M. — An Analysis of Form Regulation in Tubularia; II
Differences in Proportion in the Primordia. Arch. Entw. Mech.
23, 1907.

CONKLIN, E. G.— The World's Debt to Darwin. Proc. Am. Philos.
Society, 48, 1909.

Heredity and Environment, 5th Ed. Princeton, 1922.
The Direction of Human Evolution. New York, 1921.
The Rate of Evolution. Scientific Monthly, June, 1920.

COPE, E. D. — The Primary Factors of Organic Evolution. Chicago,
1896.

CUE'NOT, L. — La Genese des Especes Animates. Paris, 1911.

DARWIN, CHARLES — The Origin of Species, 6th Ed. London, 1872.
The Descent of Man. New York, 1871.

Variation of Animals and Plants under Domestication, 2nd Ed.
New York, 1876.

Formation of Vegetable Mould through the Action of Worms.
New York, 1882.
Life and Letters. New York, 1887.

DARWIN, ERASMUS — Zoonomia, or The Laws of Organic Life.
Dublin, 1800. ,

377

3 7 8 Problems of Organic Adaptation

DAVENPORT, C. B. — Experimental Morphology. New York, 1897-

99-
DEAN, B. — A Case of Mimicry Outmimicked. Science, N. S., Vol.

1 6, p. 832, 1902.

DRIESCH, H. — Die Biologic als selbstandige Grundwissenschaft.
Leipzig, 1893.

Die Organischen Regulationen. Leipzig, 1901.
Der Vitalismus als Geschichte und als Lehre. 1905.
Science and Philosophy of the Organism. London, 1908.
Studien iiber Anpassung und Rhythmus. Biol. Centralbl. 39,
1919.

GOLDSCHMIDT, R. — A Further Contribution to the Theory of Sex.
Jour. Exp. Zool. 22, 1917.

HARGITT, C. W. — Some Unsolved Problems of Organic Adapta-
tion. Proc. Am. Ass'n Adv. Sci. 53, 1904.

HENDERSON, L. J. — The Fitness of the Environment. New York,

J9I3-

The Order of Nature. Cambridge, Mass., 1917.

HERTWIG, O. — Zur Abwehr des ethischen, des sozialen, des poli-
tischen Darwinismus. Jena, 1918. (Quoted by Baltzer.)

JACOBS, M. H. — The Effects of Dessication on the Rotifer Philodina
roseola. Jour. Exp. Zool. 6, 1909.

JENNINGS, H. S. — Behavior of Lower Organisms. New York, 1906.
Life and Matter. Johns Hopkins Univ. Circular, No. 270, 1914.
KELLOGG, V. L. — Darwinism To-Day. New York, 1907.

KINGSBURY, B. F. — The Fitness of Organisms from an Embryolo-
gist's Viewpoint. Science, N. S. 38, pp. 174-179, 1918.

LAMARCK, J. B. P. — Zoological Philosophy, English Translation.
London, 1914.

LILLIE, F. R. — Adaptation in Cleavage. Woods Hole Lectures, 1899.

LOEB, J. — The Mechanistic Conception of Life. Chicago, 1912.

The Mechanistic Science and Metaphysical Romance. Yale Re-
view, 1915.
Forced Movements and Tropisms, and Animal Conduct. 1916.

MACFARLANE, J. M. — Causes and Course of Organic Evolution.
New York, 1918.

Literature Cited 379

MATHEWS, A. P. — Adaptation from the Point of View of the Physi-
ologist. Am. Naturalist, 1913.

METCALF, M. M. — Adaptation through Natural Selection and Or-

thogenesis. Idem, 1913.
MORGAN, C. LLOYD — Animal Life and Intelligence. Boston, 1891.

MORGAN, T. H. — Regeneration. New York, 1901.
Evolution and Adaptation. New York, 1903.
Heredity and Sex. New York, 1913.
A Critique of the Theory of Evolution. Princeton, 1916.
The Physical Basis of Heredity. Phila., 1919.

OSBORN, H. F. — From the Greeks to Darwin. New York, 1894-
Contains summaries of all the classical works on this subject,
especially those of Plato, Aristotle, Bruno, Kant, Nageli, et al.

OSTERHAUT, W. J. V.— -Tolerance of Fresh Water by Marine Plants
and its Relation to Adaptation. Bot. Gazette 63, I91?-

PARKER, G. H. — Adaptation in Animal Reactions. Am. Naturalist,

The Problem of Adaptation as illustrated by the Fur Seals, etc.
Proc. Am. Philos. Soc. 54, 1915.

PAULY, A. — Darwinismus und Lamarckismus. Munchen, 1905.

PEARL, R. — The Selection Problem. Am. Naturalist, 1917.
The Biology of Death. Sci. Monthly, 1921.

PECKHAM, GEO. W. & ELIZABETH G. — The Instincts and Habits
of the Solitary Wasps. Madison, Wise., 1898.

PHILLIPS, E. F. — The Temperature of the Honey Bee Cluster in
Winter. Bull. U. S. Dep't Agric., 1914.

PLATE, L. — Selektionsprinzip, etc., 4th Ed. Leipzig, 1913.
REINKE, JOHANNES — Einleitung in die Theoretische Biologic. Ber-
lin, 1901.

Roux, W. — Gesammelte Abhandlungen iiber Entwicklungsmechanik
der Organismen. Leipzig, 1895.

Zur Modernen Teleologie (Psychomorphologie). Arch. Entw.
Mech. 24, 1907.

Besprechungen iiber Albrecht's Teleologie und Pathologic. Idem
26, 1908.

Weitere Bemerkung iiber Psychomorphologie und Entwicklungs-
mechanik. Idem 25, 1908.

380 Problems of Organic Adaptation

SHAW, G. BERNARD — Back to Methuselah. New York, 1921.

SHERRINGTON, C. S. — Some Aspects of Animal Mechanism. Presi-
dential Address, British Assn. Adv. Sci., 1922.

SPENCER, HERBERT — Principles of Biology. New York, 1915.

SUMNER, F. B. — Adaptation and the Problem of "Organic Purpose-
fulness." Am. Naturalist, 1919.

THOMPSON, D'ARCY — Growth and Form. Cambridge, 1917.

THOMSON, J. A. — The System of Animate Nature. New York,
1920.
The Outline of Science. New York, 1922.

THORNDIKE, E. — Animal Intelligence. Psychological Review, 1897-
98.

WALLACE, A. R. — Darwinism. New York, 1889.

WARREN, H. C. — A Study of Purpose. Jour. Philos. Psych, and Sci.
Methods 13, 1916.

WEISMANN, A. — Studies on the Theory of Descent. Vol. 2, 1882.
The Germ Plasm. New York, 1893.

On Germinal Selection as a Source of Definite Variation.
Chicago, 1896.
The Theory of Evolution. London, 1904.

WHEELER, W. M. — Social Life among the Insects. Sci. Monthly,
1922.

WOLFF, G. — Der Gegenwartige Stand des Darwinismus. Leipzig,
1896.

ZURSTRASSEN, O. — Die Zweckmassigkeit. Kultur der Gegenwart
HI, 1915-

CONTENTS

Vol. VIll JANUARY, 1921 No. 1

PAI,*

I. EDUCATIONAL ENTERPRISES OF THE PILGRIM FATHERS—
Sever.il paragraph* from the Matriculation Addre*» of the ninth academic
y*r of the Rice Institute, delivered Wednesday morning, September 22, 1920 1

WHAT THE Pit GRIM FATHERS LEFT BEHIND THEM -Plymouth
Tercentenary Lecture, delivered at the Rice Institute, October 14, 1920, by
Arthur Everett Shipley, G.B.E., F.R.S., Sc.D. (Princeton), LL.U.
i^lichigan). Master of Christ's College, Cambridge . . . .. . t

III. GRAVITATION AND THE ETHER -By Harold Albert Wilton. F.R.S.,
D.Sc. (London), formerly Fellow of Trinity College, Cambridge, Professor
of Physics at the Rice Inrtiture . . IS

IV. THE INTEGRAL AND ITS GENERALIZATIONS- By Percy Joh«

Daniel!, M.A. (Cambridge), Senior Wrangler and Rayleigb Prizeman of

Bridge University, Professor of Applied Mathematics at the Rice

3*

Vol. VIII APRIL, 1921 No. 2

UNIVERSITY EXTENSION LECTURES ON DANTE IN OBSERVANCE
OF THB SIX HUNDREDTH ANNIVERSARY OF HIS DEATH — A
SERIES OF SEVEN LAY LECTURES DELIVERED AT THE RICE
INSTITUTE IN THE SPRING OF 1911.

I. Historical Background of Dante, by Curtis Howe Walker. Ph.D. (Yale).
Lecturer in European History '•i

II. The Physical Universe of Dante, by Griffith Conrad Evant, Ph.D. (Harvard),
Profesior of Pure Mathematics ... 91

III. The Aesthetic of Dante, by Henry Erne»t Conklln, M. A. (Cornell), Assistant

• t'cMor of Philosophy . .... 118

IV. Dante's Idea of Immortality, by RadosJav Andrea T*anorT, Ph.D. (Cornell),

Assistant Professor of Philosophy .... 139

V. The Political Wiitings of Dante, by Robert Granville Caldwell, Ph.D.

(Princeton), Professor of American History .170

VI. Dante and the Reaaiisence, by Albert Leon Guerard, Agfc«£ de t'Univeriite

de France, Profe»»or of Freich . . 184

VII. Dante tnd English Literature, by Stockton Axion, Litt.D. (Pittsburgh).

L.H.D. (W«-i!«yan), LL.D. (Knox), Profrt»or of Eng'.Uh Literuture .... 11*

Vol. VIII JULY. 1921 No. 3

CONDITIONS OF WORLD PEACE The second course of public lecture* on

the Godwin Foundation in Public Affairs of the Rice Institute, delivered by

Hi» Excell-ncy, the Right Honorable Sir Auckland Geddes, British Ambassador

nited States, at the City Auditorium of Houston. May 12 and 13, 1921.

I. Deeper Causes of the W I.. M7

II. Permanent I»suct of the Pea

THE BPITISH AMBASSADOR'S ADDRESS to the Students of the Rice
Inttitute in the Faculty Ch.-v 3*3

REMARKS MADE BY THB BRITISH AMBASSADOR on the occasion of hit
»i»if to the Rice Inititut* in May, 192 i '-J08

The Rice Institute Pamphlet Is published at Houston. Texas,
and /* issued in January, April. July, and Oclooer. ll teas
entered as second class matter. April 15,1915, at the post-
office at Houston, Texas, under the Act o/Augast 24, 1912

University of Toronto
Library

Acme Library Card Pocket

Under Pat. "Ret. Index File"

Made by LIBRARY BUREAU